Mitochondrial mismatch analysis is insensitive to the mutational process

Comparative phylogeography among eight Neotropical wild cat species: no single evolutionary pattern

The felid species of South America are thought to have arrived on the continent during the Great American Biotic Interchange (GABI) in the Pleistocene. However, molecular and palaeontological data do not agree on how this event affected speciation in felids. Here, we determine both the number of colonization events and the period when felines first migrated from North America to South America. In addition, we evaluate whether similar evolutionary events could have affected the eight Neotropical cat species in their levels of genetic diversity, spatial genetic structure and demographic changes. We analysed four concatenated mitochondrial genes of the jaguar, ocelot, margay, tigrina, pampas cat, Andean cat, puma and jaguarundi. The samples were representative of a wide distribution of these species in Central and South America. Our analysis suggests either three or four colonization events from North America to South America over the past 3 Myr, followed by subsequent speciation events and the attainment of high or very high genetic diversity levels for seven of the species. No unique evolutionary process was detected for any of the current Neotropical cat species.

The usefulness of maternally inherited genetic markers for phylogeographic studies in village chicken

Phylogeography plays a major role in understanding micro and macroevolutionary processes dealing with evolutionary interpretations of geographical distribution. This field integrates information from molecular genetics, population genetics, demography, and phylogeny for the interpretation of the geographical distribution of lineages. The full mtDNA sequence and W chromosome polymorphisms were exploited to assess the usefulness of two maternally-inherited genetic markers for phylogeographic studies of village chickens. We studied 243 full mtDNA sequences from three countries (Iraq, n = 27; Ethiopia, n = 211; and Saudi Arabia, n = 5) and a 13-kb fragment of the W chromosome from 20 Iraqi and 137 Ethiopian female chickens. The results show a high level of genetic diversity for the mtDNA within and among countries as well as within populations. On the other hand, sequence analysis of the W chromosome shows low genetic diversity both within and among populations. Six full mtDNA haplogroups (A, B, C1, C2, D1, and E1) were observed and 25 distinct W haplotypes. The results support the effectiveness of full mtDNA sequences but not the W chromosome in tracing the maternal historical genome background with, however, weak within a country phylogeographic signal.

Comparative mitogenome phylogeography of two anteater genera (Tamandua and Myrmecophaga; Myrmecophagidae, Xenarthra): Evidence of discrepant evolutionary traits

The species within Xenarthra (sloths, anteaters, and armadillos) are quintessential South American mammals. Of the three groups, Vermilingua (anteaters) contains the fewest extant and paleontological species. Here, we sampled and sequenced the entire mitochondrial genomes (mitogenomes) of two Tamandua species (Tamandua tetradactyla and Tamandua mexicana) (n=74) from Central and South America, as well as Myrmecophaga tridactyla (n=41) from South America. Within Tamandua, we detected three different haplogroups. The oldest (THI) contained many specimens with the T. tetradactyla morphotype (but also several with the T. mexicana morphotype) and originated in southeastern South America (currently Uruguay) before moving towards northern South America, where the THII haplogroup originated. THII primarily contained specimens with the T. mexicana morphotype (but also several with the T. tetradactyla morphotype) and was distributed in Central America, Colombia, and Ecuador. THI and THII yielded a genetic distance of 4%. THII originated in either northern South America or "in situ" in Central America with haplogroup THIII, which consisted of ~50% T. mexicana and 50% T. tetradactyla phenotypes. THIII was mostly located in the same areas as THII, i.e., Central America, Ecuador, and Colombia, though mainly in the latter. The three haplogroups overlapped in Colombia and Ecuador. Thus, T. tetradactyla and T. mexicana were not reciprocally monophyletic. For this reason, we considered that a unique species of Tamandua likely exists, i.e., T. tetradactyla. In contrast to Tamandua, M. tridactyla did not show different morphotypes throughout its geographical range in the Neotropics. However, two very divergent genetic haplogroups (MHI and MHII), with a genetic distance of ~10%, were detected. The basal haplogroup, MHI, originated in northwestern South America, whereas the more geographically derived haplogroup, MHII, overlapped with MHI, but also expanded into central and southern South America. Thus, Tamandua migrated from south to north whereas Myrmecophaga migrated from north to south. Our results also showed that temporal mitochondrial diversification for Tamandua began during the Late Pliocene and Upper Pleistocene, but for Myrmecophaga began during the Late Miocene. Furthermore, both taxa showed elevated levels of mitochondrial genetic diversity. Tamandua showed more evidence of female population expansion than Myrmecophaga. Tamandua experienced population expansion ~0.6-0.17 million years ago (Mya), whereas Myrmecophaga showed possible population expansion ~0.3-0.2 Mya. However, both taxa experienced a conspicuous female decline in the last 10 000-20 000 years. Our results also showed little spatial genetic structure for both taxa. However, several analyses revealed higher spatial structure in Tamandua than in Myrmecophaga. Therefore, Tamandua and Myrmecophaga were not subjected to the same biogeographical, geological, or climatological events in shaping their genetic structures.

Chloroplastic and nuclear diversity of endemic Prunus armeniaca L. species in the oasis agroecosystems

Tunisia is characterized by the presence of specific seed-propagated apricot (Prunus armeniaca L.) material which is found in the oasis agroecosystems. In order to highlight the genetic diversity, population structure, and demographic history of this germplasm, 33 apricot accessions collected from six different oasis regions in southwestern Tunisia were genotyped using 24 microsatellite markers. A total number of 111 alleles was detected with an average of 4.62 alleles per locus. Bayesian model-based clustering analysis indicated four subdivisions within the collection sampled that corresponded mainly to the geographic origin of the material. The analysis of the 33 accessions using chloroplast markers allowed the identification of 32 haplotypes. Overall, the present study highlighted the high Tunisian apricot's diversity in the traditional oasis agroecosystems with low genetic differentiation. Understanding the structure of seed-propagated apricot collection is crucial for managing collections in regard to adaptive traits for Arid and Saharan climates as well as for identifying interesting genotypes that can be integrated into international coordinated actions of breeding programs.

Phylogeography of the Central american red brocket deer, Mazama temama (Artiodactyla, Cervidae) in southeastern Mexico

Anthropogenic threats have increasingly isolated the populations of Mazama temama (Erxleben, 1777) and limited the gene flow in this species. Knowledge of the phylogeographic structure of this species is therefore essential for its conservation. Thus, in this study, we describe the phylogeographic structure of two M. temama populations of Veracruz and Oaxaca, Mexico. We sequenced the D-Loop region of the mitochondrial DNA of 16 individuals, in order to estimate the diversity and genetic differentiation (FST), Tajima’s D index, "Mismatch distribution" test; a phylogram and a haplotype network was constructed and we performed multidimensional scaling analysis to test the hypothesis of association between geographic distance and genetic diversity. The haplotypic and nucleotide diversity was high, indicating divergent populations (FST = 0.223), while the Tajima’s D index (-1,03300; P > 0.10) determined disequilibrium in the D-Loop region, derived from a population expansion that was evidenced in the "Mismatch distribution" test and confirmed with the haplotype network in the form of a star. Four lineages were identified in the phylogram (Veracruz n = 3, Oaxaca n = 1), evidencing geographic and reproductive isolation between the two populations. This was confirmed by the multidimensional scaling analysis, which evidenced recent evolutionary divergence between the populations analyzed, which are considered evolutionary units of conservation.

The genetic structure of the spectacled bear (Tremarctos ornatus; Ursidae, Carnivora) in Colombia by means of mitochondrial and microsatellite markers

The spectacled bear (Ursidae: Tremarctos ornatus) is an emblematic umbrella species and one of the top carnivores in the Andean mountains. It is also listed as vulnerable by IUCN and as endangered by CITES. We analyzed the genetic structure of this species in nine geographical regions representing the three Andean Cordilleras in Colombia. We sequenced six mitochondrial genes in 115 spectacled bears; a subset of these specimens (n = 61) were genotyped at seven nuclear microsatellites. We addressed three objectives: 1) determine the genetic diversity and historical demographic changes of the spectacled bear in Colombia; 2) determine phylogeographic patterns of genetic divergence among spectacled bear populations in Colombia; and 3) estimate the levels of gene flow among different regions of Colombia. Our analyses show evidence of high mitochondrial genetic diversity in spectacled bears, both in Colombia as well as in each of the nine regions, most particularly Norte de Santander, Nariño, and Antioquia-Córdoba. In addition, we detected population expansion in Colombia that occurred around 24,000 years ago, followed by a population decrease during the last 7,000 years, and a sudden expansion in the last 300 years. Phylogenetic analyses showed few well-supported clades, with some haplotypes detected in all the departments and Colombian Andean Cordilleras, and other haplotypes restricted to certain geographical areas (Antioquia, Norte de Santander, Cundinamarca, and Nariño). We detected significant genetic heterogeneity among some departments and among the three Colombian Andean Cordilleras for both mitochondrial and nuclear genes. Nevertheless, the moderate levels of gene flow estimated from FST statistics suggest that geographical barriers have not been definitive obstacles to the dispersion of the spectacled bear throughout Colombia. Despite these gene flow estimates, significant spatial autocorrelation was detected for spectacled bear in Colombia, where two kinds of spatial patterns were discovered: genetic patches of 144 km of diameter, and isolation by distance among bears separated from 578 to 800 km. The two most northern spectacled bear populations of Colombia (Norte de Santander and Antioquia) also were the two most differentiated. Their distinctiveness may qualify them as distinct Management Units (MUs) in the context of conservation policies for the spectacled bear in Colombia.

Genetics of the Andean bear (Tremarctos ornatus; Ursidae, Carnivora) in Ecuador: when the Andean Cordilleras are not an Obstacle

One of the top carnivores in the Andean mountains is the Andean bear (Tremarctos ornatus, Ursidae), the only bear in South America. This is a flagship and key umbrella species in Ecuador because its conservation has a positive impact on the conservation of many other species in the Andes. But to preserve, first one must know the genetic characteristics of a species, among other things. For this, we analyzed six mitochondrial genes and seven nuclear DNA microsatellites of 108 Andean bear specimens sampled throughout Ecuador. We adopted three strategies for analyzing the data: by Province, by Region (north vs south), and by Cordillera. Four main results were obtained. First, the mitochondrial genetic diversity levels were elevated, but there were no differences in genetic diversity by Province or by Cordillera. By Regions, southern Ecuador had higher genetic diversity levels than to northern Ecuador. The genetic diversity for the microsatellites was only medium for the Andean bear at this country. Second, there was clear and significant evidence of female population expansions, for the overall sample, by Province, Region, and Cordillera. This population expansion was determined to have occurred in the time interval of 30,000-20,000 years ago (YA), during the last phase of the Pleistocene. We detected a population decrease to have occurred more recently, within the last 5000 years. It continued until about 300-200 YA when a population increase was again detected. Third, there were, practically, no phylogeographic pattern nor genetic differentiation among Andean bear populations in Ecuador by Province or by Cordillera for either mitochondrial or microsatellite markers. There was a little more genetic differentiation between northern and southern areas. Fourth, there was no trace of significant spatial genetic structure for the Andean bear in Ecuador in agreement with the genetic differentiation analyses. This shows that the Andean Cordilleras in this country did not present an obstacle to the dispersion of this species. Therefore, all of the Andean bear specimens in Ecuador should be treated as a unique Management Unit (MU) for conservation purposes, differently to that determined for other countries as Colombia.

Invalidation of taxa within the silvery wooly monkey (Lagothrix lagothricha poeppigii, Atelidae, Primates)

The systematics of the Humboldt's wooly monkeys (L. lagothricha; Atelidae) is essential to preserve this Neotropical primate species. Traditionally, four morphological subspecies have been described, which recently have been molecularly confirmed. However, no population genetics studies have been carried out throughout the geographical distribution of one of these subspecies, Lagothrix lagothricha poeppigii. For this reason, we analyzed nine mitochondrial genes of L. l. poeppigii mainly collected from the Ecuadorian and Peruvian Amazon in order to better understand the evolutionary history of this taxon. The mitochondrial genetic diversity levels (haplotype and nucleotide diversity) we estimated are likely the highest yet reported for L. lagothricha. Our results did not detect important genetic structure within L. l. poeppigii. Furthermore, our phylogenetic analyses did not detect any relevant molecular cluster in the area where Groves hypothesized the existence of L. poeppigii castelnaui. Therefore, based on these data, castelnaui is not a valid taxon from a molecular perspective. The most differentiated subpopulation within L. l. poeppigii was from Morona-Santiago province (Ecuador) and had a genetic distance of 0.8-1.2% relative to the other subpopulations studied. However, this genetic distance range is within the variability found within a population. We estimated the mitochondrial temporal diversification within L. l. poeppigii to have occurred during the Pleistocene, 1.8-1.2 million years ago. Similarly, all our analyses detected a strong Pleistocene female population expansion for this taxon. Diverse spatial genetic analyses, perhaps with the exception of Monmonier's Algorithm, did not detect differentiated taxa within the area analyzed for L. l. poeppigii. These genetics results could be of importance to conservation efforts to preserve this taxon as one unit.

The maternal origin of indigenous domestic chicken from the Middle East, the north and the horn of Africa

Background

Indigenous domestic chicken represents a major source of protein for agricultural communities around the world. In the Middle East and Africa, they are adapted to hot dry and semi-dry areas, in contrast to their wild ancestor, the Red junglefowl, which lives in humid and sub-humid tropical areas. Indigenous populations are declining following increased demand for poultry meat and eggs, favouring the more productive exotic commercial breeds. In this paper, using the D-loop of mitochondrial DNA as a maternally inherited genetic marker, we address the question of the origin and dispersal routes of domestic chicken of the Middle East (Iraq and Saudi Arabia), the northern part of the African continent (Algeria and Libya) and the Horn of Africa (Ethiopia).

Results

The analysis of the mtDNA D-loop of 706 chicken samples from Iraq (n = 107), Saudi Arabia (n = 185), Algeria (n = 88), Libya (n = 23), Ethiopia (n = 211) and Pakistan (n = 92) show the presence of five haplogroups (A, B, C, D and E), suggesting more than one maternal origin for the studied populations. Haplogroup E, which occurred in 625 samples, was the most frequent in all countries. This haplogroup most likely originates from the Indian subcontinent and probably migrated following a terrestrial route to these different countries. Haplotypes belonging to haplogroup D were present in all countries except Algeria and Libya, it is likely a legacy of the Indian Ocean maritime trading network. Haplogroup A was present in all countries and may be of commercial origin. Haplogroup B was found only in Ethiopia. Haplogroup C was only detected in the South-Western region of Saudi Arabia and in Ethiopia.

Conclusion

The results support a major influence of the Indian subcontinent on the maternal diversity of the today’s chicken populations examined here. Most of the diversity occurs within rather than between populations. This lack of phylogeographic signal agrees with both ancient and more recent trading networks having shaped the modern-day diversity of indigenous chicken across populations and countries.

Mitochondrial phylogeography of kinkajous (Procyonidae, Carnivora): maybe not a single ESU

Knowledge of how a species is divided into different genetic units, and the structure among these units, is fundamental to the protection of biodiversity. Procyonidae was one of the families in the Order Carnivora with more success in the colonization of South America. The most divergent species in this family is the kinkajou (Potos flavus). However, knowledge of the genetics and evolution of this species is scarce. We analyzed five mitochondrial genes within 129 individuals of P. flavus from seven Neotropical countries (Mexico, Guatemala, Honduras, Colombia, Ecuador, Peru, and Bolivia). We detected eight different populations or haplogroups, although only three had highly significant bootstrap values (southern Mexico and Central America; northern Peruvian, Ecuadorian, and Colombian Amazon; and north-central Andes and the southern Amazon in Peru). Some analyses showed that the ancestor of the southern Mexico–Central America haplogroup was the first to appear. The youngest haplogroups were those at the most southern area analyzed in Peru and Bolivia. A “borrowed molecular clock” estimated the initial diversification to have occurred around 9.6 million years ago (MYA). All the spatial genetic analyses detected a very strong spatial structure with significant genetic patches (average diameter around 400–500 km) and a clinal isolation by distance among them. The overall sample and all of the haplogroups we detected had elevated levels of genetic diversity, which strongly indicates their long existence. A Bayesian Skyline Plot detected, for the overall sample and for the three most significant haplogroups, a decrease in the number of females within the last 30,000–50,000 years, with a strong decrease in the last 10,000–20,000 years. Our data supported an alignment of some but not all haplogroups with putative morphological subspecies. We have not discounted the possibility of a cryptic kinkajou species.

Contrasting phylogeographic patterns and demographic history in closely related species of Daphnia longispina group (Crustacea: Cladocera) with focus on North-Eastern Eurasia

Species with large geographic distributions present a challenge for phylogeographic studies due to the logistic difficulties of obtaining adequate samples. Daphnia O.F. Müller (Anomopoda: Daphniidae) is a model genus for evolutionary biology and ecology, but many regions such as the remote areas of Siberia, remain poorly studied. Here we examined genetic polymorphism in the ribosomal 12S and the protein-coding ND2 mitochondrial genes of three closely related taxa of the Daphnia (Daphnia) longispina complex, namely D. galeata Sars, D. longispina O.F. Müller and D. dentifera Forbes. We estimated the phylogenetic relationships among these taxa based on a concatenated alignment of these two genes. Using sequences from the present study and those available in GenBank, we investigated the geographic distributions of the mitochondrial haplotypes of these species and proposed an evolutionary scenario for each taxon. Network structures, haplotype distribution patterns, and FST values indicated significant differences in the evolutionary history of the examined species. Our analysis of D. galeata populations confirmed its recent and fast expansion, without a previous phase of a strong population disconnection. In contrast, the high haplotype diversity in D. dentifera and D. longispina could be explained by the survival of different phylogroups in several glacial refugia located in different geographic regions. For all studied species, maximum haplotype diversity was recorded in the remote regions of Siberia-lakes of the Yenisei River and Transbaikalia. Our study is an important step in our understanding of the evolutionary history of the Daphnia longispina group and provides further evidence of the biogeographic significance of Siberia for freshwater taxa.

Mitochondrial phylogeography and population structure of the cattle tick Rhipicephalus appendiculatus in the African Great Lakes region

Background

The ixodid tick Rhipicephalus appendiculatus is the main vector of Theileria parva, wich causes the highly fatal cattle disease East Coast fever (ECF) in sub-Saharan Africa. Rhipicephalus appendiculatus populations differ in their ecology, diapause behaviour and vector competence. Thus, their expansion in new areas may change the genetic structure and consequently affect the vector-pathogen system and disease outcomes. In this study we investigated the genetic distribution of R. appendiculatus across agro-ecological zones (AEZs) in the African Great Lakes region to better understand the epidemiology of ECF and elucidate R. appendiculatus evolutionary history and biogeographical colonization in Africa.

Methods

Sequencing was performed on two mitochondrial genes (cox1 and 12S rRNA) of 218 ticks collected from cattle across six AEZs along an altitudinal gradient in the Democratic Republic of Congo, Rwanda, Burundi and Tanzania. Phylogenetic relationships between tick populations were determined and evolutionary population dynamics models were assessed by mismach distribution.

Results

Population genetic analysis yielded 22 cox1 and 9 12S haplotypes in a total of 209 and 126 nucleotide sequences, respectively. Phylogenetic algorithms grouped these haplotypes for both genes into two major clades (lineages A and B). We observed significant genetic variation segregating the two lineages and low structure among populations with high degree of migration. The observed high gene flow indicates population admixture between AEZs. However, reduced number of migrants was observed between lowlands and highlands. Mismatch analysis detected a signature of rapid demographic and range expansion of lineage A. The star-like pattern of isolated and published haplotypes indicates that the two lineages evolve independently and have been subjected to expansion across Africa.

Conclusions

Two sympatric R. appendiculatus lineages occur in the Great Lakes region. Lineage A, the most diverse and ubiquitous, has experienced rapid population growth and range expansion in all AEZs probably through cattle movement, whereas lineage B, the less abundant, has probably established a founder population from recent colonization events and its occurrence decreases with altitude. These two lineages are sympatric in central and eastern Africa and allopatric in southern Africa. The observed colonization pattern may strongly affect the transmission system and may explain ECF endemic instability in the tick distribution fringes.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-2904-7) contains supplementary material, which is available to authorized users.

Phylogeography of the Mantled Howler Monkey (Alouatta palliata; Atelidae, Primates) across Its Geographical Range by Means of Mitochondrial Genetic Analyses and New Insights about the Phylogeny of Alouatta

We analyzed 156 specimens of diverse howler monkey taxa (Alouatta; Atelidae, Primates) for different mitochondrial genes (5,567 base pairs), with special emphasis on A. palliata and related taxa. Our results showed no relevant differences among individuals of different putative taxa, A. p. palliata, A. p. aequatorialis, A. coibensis coibensis, and A. c. trabeata. We found no spatial differences in genetic structure of A. p. palliata throughout Costa Rica, Nicaragua, and Honduras. A. p. mexicana (genetic distance: 1.6-2.1%) was the most differentiated taxon within A. palliata. Therefore, we postulate the existence of only 2 clearly defined subspecies within A. palliata (A. p. palliata and A. p. mexicana). A. palliata and A. pigra (traditionally considered a subspecies of A. palliata) are 2 clearly differentiated species as was demonstrated by Cortés-Ortiz and colleagues in 2003, with a temporal split between the 2 species around 3.6-3.7 million years ago (MYA). Our results with the Median Joining Network procedure showed that the ancestors of the cis-Andean Alouatta gave rise to the ancestors of the trans-Andean Alouatta around 6.0-6.9 MYA. As Cortés-Ortiz et al. showed, A. sara and A. macconnelli are differentiable species from A. seniculus, although the first 2 taxa were traditionally considered subspecies of A. seniculus. Our findings agree with the possibility that the ancestor of A. sara gave rise to the ancestor of A. pigra in northern South America. In turn, the ancestor of A. pigra originated the ancestor of A. palliata. Two of our results strongly support the hypothesis that the South American A. palliata (the putative A. p. aequatorialis) was the original population of this species; it has high genetic diversity and no evidence of population expansion. The Central America A. palliata is the derived population. It has low genetic diversity and there is clear evidence of population expansion. However, A. palliata and A. pigra probably migrated into Central America by 2 different routes: the Isthmus of Panama (A. palliata) and Caribbean island arch (A. pigra). Finally, the red howler monkeys from the island of Trinidad in the Caribbean Sea were not A. macconnelli (= A. s. stramineus) as Groves maintained in his influential 2001 publication on primate taxonomy. This taxon is more related to A. s. seniculus, although it formed a monophyletic clade. Future molecular and karyotypic studies will show if the Trinidad red howler monkeys should be considered as an extension of the Venezuelan taxon, A. arctoidea, as a subspecies of A. seniculus(A. s. seniculus), or, in the case of extensive chromosomal rearrangements, even a new species.

Highly contrasted population genetic structures in a host-parasite pair in the Caribbean Sea

Evolution and population genetic structure of marine species across the Caribbean Sea are shaped by two complex factors: the geological history and the present pattern of marine currents. Characterizing and comparing the genetic structures of codistributed species, such as host-parasite associations, allow discriminating the relative importance of environmental factors and life history traits that influenced gene flow and demographic events. Using microsatellite and Cytochrome Oxidase I markers, we investigated if a host-parasite pair (the heart urchin Meoma ventricosa and its parasitic pea crab Dissodactylus primitivus) exhibits comparable population genetic structures in the Caribbean Sea and how the observed patterns match connectivity regions from predictive models and other taxa. Highly contrasting patterns were found: the host showed genetic homogeneity across the whole studied area, whereas the parasite displayed significant differentiation at regional and local scales. The genetic diversity of the parasitic crabs (both in microsatellites and COI) was distributed in two main groups, Panama-Jamaica-St Croix on the one hand, and the South-Eastern Caribbean on the other. At a smaller geographical scale, Panamanian and Jamaican parasite populations were genetically more similar, while more genetic differentiation was found within the Lesser Antilles. Both species showed a signature of population expansion during the Quaternary. Some results match predictive models or data from previous studies (e.g., the Western-Eastern dichotomy in the parasite) while others do not (e.g., genetic differentiation within the Lesser Antilles). The sharp dissimilarity of genetic structure of these codistributed species outlines the importance of population expansion events and/or contrasted patterns of gene flow. This might be linked to differences in several life history traits such as fecundity (higher for the host), swimming capacity of larval stages (higher for the parasite), and habitat availability (higher for the host).

Genetic Relationships and Spatial Genetic Structure Among Populations of Rhodnius prolixus (Hemiptera: Reduviidae) in Colombia and Venezuela Based on Mitochondrial Cytochrome-b Sequences

One hundred twenty Rhodnius prolixus (Stal) (Hemiptera: Reduviidae) specimens from 6 Colombian Departments and 1 Venezuelan State had 594-bp of the mitochondrial cytochrome-b gene sequenced to improve the understanding of evolutionary processes that shape the main vector of Chagas disease. The levels of genetic diversity for this species were low-medium with reference to other bugs. The genetic heterogeneity among the populations was very limited which means there has been extensive gene flow and/or very recent split processes. The overall sample as well as some individual populations showed evidence of recent population expansions (with the exception of Arauca, which yielded evidence of a bottleneck for a mismatch distribution). This expansion (11,000 or 2000-25,000 year ago depending of two procedures employed) coincides with the ending of the last intense glacial conditions during the Pleistocene and the beginning of the Holocene that had a warmer and wetter climate. Some of our autocorrelation analyses (AIDA and Genetic Landscape Interpolation Analysis) indicated local patches of high genetic similarity but no globally significant spatial structure. We did show an original haplotype distributed throughout the entirety of the geographical area studied.

Shaken not stirred: A molecular contribution to the systematics of genus Mugil (Teleostei, Mugilidae)

With this work we addressed some molecular systematic issues within the Mugil cephalus species complex. Particular attention was paid to the debated situations of: (i) Mugil liza, occurring in partial sympatry with Mugil cephalus in the northwestern Atlantic, and (ii) Mugil platanus, considered by some authors a synonymy of the former species and distributed in the southwestern Atlantic. We sequenced 79 individuals of a 465-bp portion of the mitochondrial control region (CR) from 8 western Atlantic and 2 Mediterranean localities. In addition, all CR sequences available from GenBank for the studied taxa were added to our dataset, for a total of 323 individuals. Overall, 229 haplotypes corresponding to 8 divergent monophyletic lineages were detected. Results of phylogenetic analyses were consistent with the occurrence of past speciation events producing the observed lineages. Of these lineages, 7 correspond to cryptic species and one is constituted by M. liza and M. platanus. As a matter of fact, these 2 taxa constitute a single lineage within the M. cephalus species complex. However, individuals of M. liza/M. platanus lineage analyzed by means of the 18 mitochondrial markers available in GenBank exhibited a degree of genetic diversity consistent with highly divergent populations. Of the 8 lineages detected, the Mediterraean one (type locality) corresponds to M. cephalus; the lineage M. liza/M. platanus should be named M. liza, under the priority principle, and the left 6 lineages need formal description.

Exploring the role of within-island ecogeographical factors: insights from the genetic diversity of Cretan trap-door spiders (Cyrtocarenum cunicularium, Ctenizidae : Araneae)

Crete (Aegean Sea, Greece), like other Mediterranean islands, has a complex palaeogeographical history, including several cycles of fragmentation into palaeoislands and subsequent reconnection. Here, we use the Cretan trap-door spider Cyrtocarenum cunicularium as a model organism to explore the importance of within-island evolutionary processes, such as palaeogeographic events and climatic changes. We assessed the phylogeny, population clustering and historical demography of 61 specimens with mitochondrial (COI) and nuclear (H3) markers. We investigated the isolation-by-distance and spatial diffusion processes that have shaped their past and current distribution and estimated the effect of niche divergence, using species distribution modelling. Two genetic lineages have continuously been distributed in the west and east part of Crete during the last 2million years. Their genetic structure is concordant with Crete’s fragmentation into palaeoislands during the Pliocene and additionally affected by the sea-level oscillations and climatic changes due to the Pleistocenic glacial cycles. In central Crete, some evidence of genetic admixture between them was found, which needs to be further explored. According to species distribution modelling, the niche of each lineage corresponds to different environmental parameters, while isolation-by-distance was also detected. The divergence between the ‘West’ and ‘East’ lineages was promoted by palaeogeographical factors but seems to be maintained by the species’ poor dispersal abilities and the local ecological adaptation of each lineage. The case of the Cretan C. cunicularium highlights the additive effect of ecogeographical and behavioural factors in shaping insular biodiversity.

Population dynamics of Anopheles nuneztovari in Colombia

Anopheles nuneztovari is an important Colombian malaria vector widespread on both sides of the Andean Mountains, presenting morphological, behavioral and genetic heterogeneity throughout the country. The aim of this study was to evaluate whether the population structure and distribution of An. nuneztovari in Colombia are associated with ecological and physical barriers present in a heterogeneous landscape. Further, differences in behavior were addressed. A total of 5392 specimens of An. nuneztovari were collected. Mitochondrial and nuclear marker analyses detected subdivision among the northwest-west, northeast and east populations. For both markers, isolation by distance (~53%) and isolation by resistance (>30%) were determinants of population genetic differentiation. This suggests that physical barriers, geographical distance and ecological differences on both sides of the Andean Mountains promoted the genetic differentiation and population subdivision of An. nuneztovari in Colombia. This species showed the highest biting activity after 20:00h; indoor and outdoor preferences were found in all localities. These results indicated that the most effective interventions for controlling vector populations on both sides of the Andes need to be region-specific.

Phylogeny and diversification of mountain vipers (Montivipera, Nilson et al., 2001) triggered by multiple Plio-Pleistocene refugia and high-mountain topography in the Near and Middle East

The Near and Middle East is a hotspot of biodiversity, but the region remains underexplored at the level of genetic biodiversity. Here, we present an extensive molecular phylogeny of the viperid snake genus Montivipera, including all known taxa. Based on nuclear and mitochondrial data, we present novel insights into the phylogeny of the genus and review the status of its constituent species. Maximum likelihood methods revealed a montane origin of Montivipera at 12.3Mya. We then analyzed factors of mountain viper diversity. Our data support substantial changes in effective population size through Plio-Pleistocene periods. We conclude that climatic oscillations were drivers of allopatric speciation, and that mountain systems of the Near and Middle East have strongly influenced the evolution and survival of taxa, because climatic and topographical heterogeneities induced by mountains have played a crucial role as filters for dispersal and as multiple refugia. The wide diversity of montane microhabitats enabled mountain vipers to retain their ecological niche during climatic pessima. In consequence the varied geological and topographical conditions between refugia favoured genetic isolation and created patterns of species richness resulting in the formation of neoendemic taxa. Our data support high concordance between geographic distributions of Montivipera haplotypes with putative plant refugia.

Molecular and iridescent feather reflectance data reveal recent genetic diversification and phenotypic differentiation in a cloud forest hummingbird

The present day distribution and spatial genetic diversity of Mesoamerican biota reflects a long history of responses to habitat change. The hummingbird Lampornis amethystinus is distributed in northern Mesoamerica, with geographically disjunct populations. Based on sampling across the species range using mitochondrial DNA (mtDNA) sequences and nuclear microsatellites jointly analysed with phenotypic and climatic data, we (1) test whether the fragmented distribution is correlated with main evolutionary lineages, (2) assess body size and plumage color differentiation of populations in geographic isolation, and (3) evaluate a set of divergence scenarios and demographic patterns of the hummingbird populations. Analysis of genetic variation revealed four main groups: blue‐throated populations (Sierra Madre del Sur); two groups of amethyst‐throated populations (Trans‐Mexican Volcanic Belt and Sierra Madre Oriental); and populations east of the Isthmus of Tehuantepec (IT) with males showing an amethyst throat. The most basal split is estimated to have originated in the Pleistocene, 2.39–0.57 million years ago (MYA), and corresponded to groups of populations separated by the IT. However, the estimated recent divergence time between blue‐ and amethyst‐throated populations does not correspond to the 2‐MY needed to be in isolation for substantial plumage divergence, likely because structurally iridescent colors are more malleable than others. Results of species distribution modeling and Approximate Bayesian Computation analysis fit a model of lineage divergence west of the Isthmus after the Last Glacial Maximum (LGM), and that the species’ suitable habitat was disjunct during past and current conditions. These results challenge the generality of the contraction/expansion glacial model to cloud forest‐interior species and urges management of cloud forest, a highly vulnerable ecosystem to climate change and currently facing destruction, to prevent further loss of genetic diversity or extinction.

Behavior and population structure of Anopheles darlingi in Colombia

Anopheles darlingi is a widely distributed and important malaria vector in Colombia. Biogeographical and ecological heterogeneity across the Colombian distribution led to the hypothesis of behavioral and genetic differentiation among A. darlingi populations. A total of 2017 A. darlingi specimens were collected during 222 h of sampling. This vector was the most abundant anopheline species in most of the localities sampled. Subdivision between samples collected west and east of the Andes was indicated by 1) mitochondrial COI and nuclear CAD sequences from NW-W and CE-S populations (COI ΦST=0.48761-0.81974, CAD FST=0.11319-0.21321), 2) a COI haplotype network, and 3) SAMOVA. Endo- and exophagy were detected in populations west of the Andes, whereas exophagy was evident in PTG, a locality east of the Andes. Isolation by resistance was significant for COI and explained 26% of the genetic differentiation. We suggest that at a macrogeographic scale, the Andes influence the differentiation of A. darlingi in Colombia and may drive divergence, and, at a microgeographic scale, ecological differences have a significant impact on structure. These data could constitute a baseline for the design of effective vector interventions, locality-specific for the east and similar for panmictic populations west of the Andes.

Independent Demographic Responses to Climate Change among Temperate and Tropical Milksnakes (Colubridae: Genus Lampropeltis)

The effects of Late Quaternary climate change have been examined for many temperate New World taxa, but the impact of Pleistocene glacial cycles on Neotropical taxa is less well understood, specifically with respect to changes in population demography. Here, we examine historical demographic trends for six species of milksnake with representatives in both the temperate and tropical Americas to determine if species share responses to climate change as a taxon or by area (i.e., temperate versus tropical environments). Using a multilocus dataset, we test for the demographic signature of population expansion and decline using non-genealogical summary statistics, as well as coalescent-based methods. In addition, we determine whether range sizes are correlated with effective population sizes for milksnakes. Results indicate that there are no identifiable trends with respect to demographic response based on location, and that species responded to changing climates independently, with tropical taxa showing greater instability. There is also no correlation between range size and effective population size, with the largest population size belonging to the species with the smallest geographic distribution. Our study highlights the importance of not generalizing the demographic histories of taxa by region and further illustrates that the New World tropics may not have been a stable refuge during the Pleistocene.

Incongruent nuclear and mitochondrial genetic structure of new world screwworm fly populations due to positive selection of mutations associated with dimethyl- and diethyl-organophosphates resistance

Livestock production is an important economic activity in Brazil, which has been suffering significant losses due to the impact of parasites. The New World screwworm (NWS) fly, Cochliomyia hominivorax, is an ectoparasite and one of the most important myiasis-causing flies endemic to the Americas. The geographic distribution of NWS has been reduced after the implementation of the Sterile Insect Technique (SIT), being eradicated in North America and part of Central America. In South America, C. hominivorax is controlled by chemical insecticides, although indiscriminate use can cause selection of resistant individuals. Previous studies have associated the Gly137Asp and Trp251Leu mutations in the active site of carboxylesterase E3 to resistance of diethyl and dimethyl-organophosphates insecticides, respectively. Here, we have sequenced a fragment of the carboxylesterase E3 gene (ChαE7), comprising part of intron iII, exon eIII, intron iIII and part of exon eIV, and three mitochondrial gene sequences (CR, COI and COII), of NWS flies from 21 locations in South America. These markers were used for population structure analyses and the ChαE7 gene was also investigated to gain insight into the selective pressures that have shaped its evolution. Analysis of molecular variance (AMOVA) and pairwise FST analysis indicated an increased genetic structure between locations in the ChαE7 compared to the concatenated mitochondrial genes. Discriminant analysis of principal components (DAPC) and spatial analysis of molecular variance (SAMOVA) indicated different degrees of genetic structure for all markers, in agreement with the AMOVA results, but with low correlation to geographic data. The NWS fly is considered a panmitic species based on mitochondrial data, while it is structured into three groups considering the ChαE7 gene. A negative association between the two mutations related to organophosphate resistance and Fay & Wu’s H significant negative values for the exons, suggest that these mutations evolved under positive selection.

Genetic characterization and structure of the endemic Colombian silvery brown bare-face tamarin, Saguinus leucopus (Callitrichinae, Cebidae, Primates)

We analyzed 115 Saguinus leucopus, from four Colombian departments (Antioquia, Bolivar, Caldas and Tolima ), for 701 bp of the mt COII gene and at 10 microsatellite loci to estimate gene diversity levels, possible molecular subspecies and historical demographic changes in this species. This endemic Colombian species showed an elevated gene diversity in this gene, although its geographical distribution is very restrictive and extremely threatened by habitat fragmentation. The mt COII gene did not show any geographical structure in the distribution of the haplotypes within this species, but it did show a noteworthy population expansion throughout the history of this species. A Bayesian analysis showed that the haplotype diversification of this species began around 1.6 million years ago (MYA), whilst a haplotype network gave the beginning of this diversification at around 0.5-0.6 MYA. Forty-seven individuals out of the 115 were analyzed for 10 DNA microsatellites. The genetic diversity was relatively elevated for this kind of marker too, and comparable to that found in other Neotropical monkeys with a wider geographical distribution. Two gene pools were detected with the microsatellites, one in the northern distribution area (Antioquia) and the other in the southern distribution area (Tolima). No tests detected any bottleneck affecting this population; however, two procedures (k test and Kimmel et al. 1998 test) detected significant population expansion for the microsatellite markers, like that seen with the mt COII gene.

Killer whale nuclear genome and mtDNA reveal widespread population bottleneck during the last glacial maximum

Ecosystem function and resilience is determined by the interactions and independent contributions of individual species. Apex predators play a disproportionately determinant role through their influence and dependence on the dynamics of prey species. Their demographic fluctuations are thus likely to reflect changes in their respective ecological communities and habitat. Here, we investigate the historical population dynamics of the killer whale based on draft nuclear genome data for the Northern Hemisphere and mtDNA data worldwide. We infer a relatively stable population size throughout most of the Pleistocene, followed by an order of magnitude decline and bottleneck during the Weichselian glacial period. Global mtDNA data indicate that while most populations declined, at least one population retained diversity in a stable, productive ecosystem off southern Africa. We conclude that environmental changes during the last glacial period promoted the decline of a top ocean predator, that these events contributed to the pattern of diversity among extant populations, and that the relatively high diversity of a population currently in productive, stable habitat off South Africa suggests a role for ocean productivity in the widespread decline.

Molecular evidence of demographic expansion of the chagas disease vector Triatoma dimidiata (Hemiptera, Reduviidae, Triatominae) in Colombia

Background

Triatoma dimidiata is one of the most significant vectors of Chagas disease in Central America and Colombia, and, as in most species, its pattern of genetic variation within and among populations is strongly affected by its phylogeographic history. A putative origin from Central America has been proposed for Colombian populations, and high genetic differentiation among three biographically different population groups has recently been evidenced. Analyses based on putatively neutral markers provide data from which past events, such as population expansions and colonization, can be inferred. We analyzed the genealogies of the nicotinamide adenine dinucleotide dehydrogenase 4 (ND4) and the cytochrome oxidase subunit 1-mitochondrial genes, as well as partial nuclear ITS-2 DNA sequences obtained across most of the eco-geographical range in Colombia, to assess the population structure and demographic factors that may explain the geographical distribution of T. dimidiata in this country.

Results

The population structure results support a significant association between genetic divergence and the eco-geographical location of population groups, suggesting that clear signals of demographic expansion can explain the geographical distribution of haplotypes of population groups. Additionally, empirical date estimation of the event suggests that the population's expansion can be placed after the emergence of the Panama Isthmus, and that it was possibly followed by a population fragmentation process, perhaps resulting from local adaptation accomplished by orographic factors such as geographical isolation.

Conclusion

Inferences about the historical population processes in Colombian T. dimidiata populations are generally in accordance with population expansions that may have been accomplished by two important biotic and orographic events such as the Great American Interchange and the uplift of the eastern range of the Andes mountains in central Colombia.

The Chagas disease vector Triatoma dimidiata is one of the most important vectors in America, owing to its wide genetic and epidemiological heterogeneity. Colombian T. dimidiata populations occupy eclectic sylvatic ecotopes, but have also been found in dwellings infected with Trypanosoma cruzi, and therefore it is considered (along with Rhodnius prolixus) the most important vector in several departments. The current study explores the population structure history of Colombian populations by means of a molecular coalescence approach. The results indicate that the historical population processes in T. dimidiata in Colombia are in accordance with population expansions that may have been accomplished by two important biotic and orographic events such as the Great American Interchange and the uplift of the eastern range of the Andes Mountains in central Colombia. The genetic history as well as the heterogeneity of the populations could be reflected in different responses of the populations to vector control interventions; thus, a local level of entomological vigilance should be implemented to evaluate the intervention results in each region.

The genetic structure of the Kuwaiti population: mtDNA Inter- and intra-population variation

This study investigated: (1) the mitochondrial DNA (mtDNA) genetic variation in 116 unrelated individuals who originated from the Arabian Peninsula, Iran, or were of Bedouin ethnicity and (2) the genetic structure of Kuwaiti populations and compared it to their neighboring populations. These subpopulations were tested for genetic homogeneity and shown to be heterogeneous. Restriction fragment length polymorphism (RFLP) and mtDNA sequencing analyses of HVRI were used to reconstruct the genetic structure of Kuwait. The results indicated that the combined Kuwaiti population has a high frequency of haplogroup R0 (17%), J (12%), and U (12%) similar to other Arabian populations. In addition, contemporary African gene flow was detected through the presence of sub-haplogroup L (L1 and L2) (2%) and the absence of L3 which is reflective of an earlier migration. Furthermore, the multidimensional scaling (MDS) plot showed that the Kuwaiti population clusters with neighboring populations, including Iran and Saudi Arabia indicating gene flow into Kuwait. According to this study, the Kuwaiti population may be undergoing an expansion in a relatively short period of time, and the maternal genetic structure of Kuwait resembles both Saudi Arabia and Iran.

Balancing genetic uniqueness and genetic variation in determining conservation and translocation strategies: a comprehensive case study of threatened dwarf galaxias, Galaxiella pusilla (Mack) (Pisces: Galaxiidae)

Genetic markers are widely used to define and manage populations of threatened species based on the notion that populations with unique lineages of mtDNA and well-differentiated nuclear marker frequencies should be treated separately. However, a danger of this approach is that genetic uniqueness might be emphasized at the cost of genetic diversity, which is essential for adaptation and is potentially boosted by mixing geographically separate populations. Here, we re-explore the issue of defining management units, focussing on a detailed study of Galaxiella pusilla, a small freshwater fish of national conservation significance in Australia. Using a combination of microsatellite and mitochondrial markers, 51 populations across the species range were surveyed for genetic structure and diversity. We found an inverse relationship between genetic differentiation and genetic diversity, highlighting a long-term risk of deliberate isolation of G. pusilla populations based on protection of unique lineages. Instead, we adopt a method for identifying genetic management units that takes into consideration both uniqueness and genetic variation. This produced a management framework to guide future translocation and re-introduction efforts for G. pusilla, which contrasted to the framework based on a more traditional approach that may overlook important genetic variation in populations.

Phylogeographic patterns of mtDNA variation revealed multiple glacial refugia for the frog species Feirana taihangnica endemic to the Qinling Mountains

Diversification patterns and demography of montane species are affected by Pleistocene climate fluctuations. Empirical cases from the Qinling Mountains (QM) region, which is a major biogeographic divider of East Asia, are few. We used DNA sequence data of the complete mitochondrial ND2 gene to detect effects of the Pleistocene glaciations on phylogeographic profiles of a frog species, Feirana taihangnica, which is endemic to the QM. Four distinct lineages consisting of seven sublineages were revealed. The strongest signal of biogeographical structure (F(ct) = 0.971, P < 0.01) was found when populations were grouped according to these seven sublineages. One narrow secondary contact zone was detected in the middle QM between the lineage from middle QM and the lineage from eastern QM. Coalescent simulations indicated that this species colonized the QM region by a stepping-stone model. Divergences among lineages had likely been influenced by the uplift of the Tibetan Plateau during the late Miocene-to-late Pleistocene, as well as by the Pleistocene climatic cycles. Coalescent simulations also suggested that F. taihangnica populations have persisted through the Pleistocene glacial periods in multiple refugia across the QM region. Demographic analyses indicated that all lineages, except the lineage in the Funiu Mountains, have been experienced postglacial expansion of population size and distribution range. In conclusion, Pleistocene climate fluctuations and tectonic changes during the late Miocene-late Pleistocene have profoundly influenced the phylogeography and historical demography of F. taihangnica.

Extremely low genetic diversity indicating the endangered status of Ranodon sibiricus (Amphibia: Caudata) and implications for phylogeography

BACKGROUND

The Siberian salamander (Ranodon sibiricus), distributed in geographically isolated areas of Central Asia, is an ideal alpine species for studies of conservation and phylogeography. However, there are few data regarding the genetic diversity in R. sibiricus populations.

METHODOLOGY/PRINCIPAL FINDINGS

We used two genetic markers (mtDNA and microsatellites) to survey all six populations of R. sibiricus in China. Both of the markers revealed extreme genetic uniformity among these populations. There were only three haplotypes in the mtDNA, and the overall nucleotide diversity in the mtDNA was 0.00064, ranging from 0.00000 to 0.00091 for the six populations. Although we recovered 70 sequences containing microsatellite repeats, there were only two loci that displayed polymorphism. We used the approximate Bayesian computation (ABC) method to study the demographic history of the populations. This analysis suggested that the extant populations diverged from the ancestral population approximately 120 years ago and that the historical population size was much larger than the present population size; i.e., R. sibiricus has experienced dramatic population declines.

CONCLUSION/SIGNIFICANCE

Our findings suggest that the genetic diversity in the R. sibiricus populations is the lowest among all investigated amphibians. We conclude that the isolation of R. sibiricus populations occurred recently and was a result of recent human activity and/or climatic changes. The Pleistocene glaciation oscillations may have facilitated intraspecies genetic homogeneity rather than enhanced divergence. A low genomic evolutionary rate and elevated inbreeding frequency may have also contributed to the low genetic variation observed in this species. Our findings indicate the urgency of implementing a protection plan for this endangered species.

Influence of finite-sites mutation, population subdivision and sampling schemes on patterns of nucleotide polymorphism for species with molecular hyperdiversity

Molecular hyperdiversity has been documented in viruses, prokaryotes and eukaryotes. Such organisms undermine the assumptions of the infinite-sites mutational model, because multiple mutational events at a site comprise a non-negligible portion of polymorphisms. Moreover, different sampling schemes of individuals from species with subdivided populations can profoundly influence resulting patterns and interpretations of molecular variation. Inspired by molecular hyperdiversity in the nematode Caenorhabditis sp. 5, which exhibits average pairwise differences among synonymous sites of >5% as well as modest population structure, we investigated via coalescent simulation the joint effects of a finite-sites mutation (FSM) process and population subdivision on the variant frequency spectrum. From many demes interconnected through a stepping-stone migration model, we constructed local samples from a single deme, pooled samples from several demes and scattered samples of a single individual from numerous demes. Compared with a single panmictic population at equilibrium, we find that high population mutation rates induce a deficit of rare variants (positive Tajima's D) under a FSM model. Population structure also induces such a skew for local samples when migration is high and for pooled samples when migration is low. Contrasts of sampling schemes for C. sp. 5 imply high mutational input coupled with high migration. We propose that joint analysis of local, pooled and scattered samples for species with subdivided populations provides a means of improving inference of demographic history, by virtue of the partially distinct patterns of polymorphism that manifest when sequences are analyzed according to differing sampling schemes.

Comparative phylogeography of two co-distributed species of lizards of the genus Liolaemus (Squamata: Tropiduridae) from Southern Chile

Comparative phylogeography describes the patterns of evolutionary divergence and whether or not they are congruent, in co-distributed populations of different taxa. If the populations of these taxa have been co-distributed for a prolonged time, and if the times between processes of perturbation or vicariance have been more or less stable, it is expected that patterns of divergence will be congruent in closely related species, for example because of similar biological and demographic characteristics.Liolaemus pictusandL. cyanogasterare widely co-distributed lizard species in southern Chile, occurring in a region with a complex topology. We analyzed the phylogeographic structure of the two lizard species usingCytochromebDNA sequences to estimate their genetic structure in response to historical events. Our results suggest an evolutionary pattern of genetic diversity for each species that is consistent with the geomorphological history of the region, suggesting a complex phylogeographic history inLiolaemusspecies. Also, the high levels of divergence among haplotypes in several populations suggest the possibility that their origin might predate the middle Pleistocene in both species. Finally, our results are consistent with our hypothesis that two species have responded to historical events in parallel, where historical process have been sufficient to influence their phylogeographical structure (0.80 congruency between topologies).

Amphibian phylogeography in the Antipodes: Refugia and postglacial colonization explain mitochondrial haplotype distribution in the Patagonian frog Eupsophus calcaratus (Cycloramphidae)

Climatic oscillations, heterogeneity in elevation, topographical position, and isolation time in southwestern Patagonia have been important in promoting diversification of the biota. Geological studies have shown that this region had wide ice-free areas during periods of the last glacial maximum and provided forested refugia for the biota during Pleistocene glaciations. In this study, we sampled the endemic frog Eupsophus calcaratus from 20 localities, covering most of its distribution and including glaciated and non-glaciated regions. We collected DNA sequences for three mitochondrial regions (D-loop, cyt b, 16S), and describe patterns of variation consistent with a history of both the displacement to glacial refugia and recent recolonization to extensively glaciated regions. The inferred demographic history and divergence times of the lineages of E. calcaratus suggest that the Pleistocene had profound effects on the genetic patterns within this taxon in which some populations were able to survive in refugia within colder regions followed by demographic increases but without evidence of significant range expansion. The mtDNA gene tree recovers six major haploclades of E. calcaratus, which we consider diagnostic of species lineages. These results contribute to our understanding of how geological events, predominately glacial oscillations, have influenced current population structure of a broad-ranging, ectothermic vertebrate in the Valdivian Forest region of southern South America.

Demographic stability metrics for conservation prioritization of isolated populations

Systems of geographically isolated habitat patches house species that occur naturally as small, disjunct populations. Many of these species are of conservation concern, particularly under the interacting influences of isolation and rapid global change. One potential conservation strategy is to prioritize the populations most likely to persist through change and act as sources for future recolonization of less stable localities. We propose an approach to classify long-term population stability (and, presumably, future persistence potential) with composite demographic metrics derived from standard population-genetic data. Stability metrics can be related to simple habitat measures for a straightforward method of classifying localities to inform conservation management. We tested these ideas in a system of isolated desert headwater streams with mitochondrial sequence data from 16 populations of a flightless aquatic insect. Populations exhibited a wide range of stability scores, which were significantly predicted by dry-season aquatic habitat size. This preliminary test suggests strong potential for our proposed method of classifying isolated populations according to persistence potential. The approach is complementary to existing methods for prioritizing local habitats according to diversity patterns and should be tested further in other systems and with additional loci to inform composite demographic stability scores.

Phylogeographic and demographic effects of Pleistocene climatic fluctuations in a montane salamander, Plethodon fourchensis

Climatic changes associated with Pleistocene glacial cycles profoundly affected species distributions, patterns of interpopulation gene flow, and demography. In species restricted to montane habitats, ranges may expand and contract along an elevational gradients in response to environmental fluctuations and create high levels of genetic variation among populations on different mountains. The salamander Plethodon fourchensis is restricted to high-elevation, mesic forest on five montane isolates in the Ouachita Mountains. We used DNA sequence data along with ecological niche modelling and coalescent simulations to test several hypotheses related to the effects of Pleistocene climatic fluctuations on species in montane habitats. Our results revealed that P. fourchensis is composed of four well-supported, geographically structured lineages. Geographic breaks between lineages occurred in the vicinity of major valleys and a narrow high-elevation pass. Ecological niche modelling predicted that environmental conditions in valleys separating most mountains are suitable; however, interglacial periods like the present are predicted to be times of range expansion in P. fourchensis. Divergence dating and coalescent simulations indicated that lineage diversification occurred during the Middle Pleistocene via the fragmentation of a wide-ranging ancestor. Bayesian skyline plots showed gradual decreases in population size in three of four lineages over the most recent glacial period and a slight to moderate amount of population growth during the Holocene. Our results not only demonstrate that climatic changes during the Pleistocene had profound effects on species restricted to montane habitats, but comparison of our results for P. fourchensis with its parapatric, sister taxon, P. ouachitae, also emphasizes how responses can vary substantially even among closely related, similarly distributed taxa.