Habitat Fragmentation Differentially Affects Genetic Variation, Phenotypic Plasticity and Survival in Populations of a Gypsum Endemic

Microclimate and Dry Years Interfere With Landscape Structure Effects on Intraspecific Trait Variation

Predicting how changes in climate and land use jointly impact populations is a pressing task in ecology. Microclimate plays a key role in species' local persistence by modulating regional weather effects. However, empirical evidence remains limited regarding the relative effects of landscape structure and microclimate conditions on intraspecific trait variation. Using a spatially and temporally replicated demographic dataset, we tested the relative effects of landscape structure (area and connectivity of remnant habitat fragments), microclimate (heat load), and annual weather conditions (study year) on intraspecific variation in plant traits. We also investigated whether local heat load modulated the weather effects on the traits studied. We performed repeated measurements of stem height, leaf area, number of stems, main inflorescence length, and number of primary side inflorescences of 569 permanently marked individuals of the grassland specialist Salvia nemorosa L. We sampled 13 populations encompassing microhabitats exposed to different heat load levels over three consecutive years. Mature individuals had fewer stems in isolated and taller stems in small habitat fragments. High levels of heat load and dry years affected negatively all measured traits, and the negative effects of exposure to high heat load were generally exacerbated in dry years. Our results suggest that exposure to strong environmental stressors may complicate the detection of the real effect of human impact on plant populations. Effective landscape planning for the conservation of dry grassland species should prioritize not only improved habitat connectivity but also the maintenance of habitats with heterogeneous microclimates capable of buffering weather extremes.

Phylogenetics and population structure of the western North American endemic Pacific Laurasian clade of Isoëtes

PREMISE

Isoëtes is a genus of small, semi-woody, hydrophilic, heterosporous lycophytes with a cosmopolitan, global distribution. However, local populations tend to be found in narrow, patchy, and highly fragmented mesic to aquatic habitats, many of which are currently under threat. In this study, we sought to uncover how this patchy distribution has affected the evolutionary history of one of the two lineages of Isoëtes found on the West Coast of North America-the Pacific Laurasian clade (PLC).

METHODS

We used a combination of population genetic and multilocus molecular phylogenetic approaches to infer the relationships among the three described species in this clade and to determine the degree of isolation among the sampled populations.

RESULTS

We discovered that the populations studied are highly structured and that two of the species, as currently circumscribed, are not monophyletic. Instead, our phylogenetic results suggest that there are at least eight distinct "species-level" clades within the PLC. Of these eight, five appear to have been the result of a rapid radiation.

CONCLUSIONS

Our results suggest that the existing taxonomy does not reflect the actual diversity in the PLC and warrants further investigation.

Arbuscular mycorrhizae reduce the response of important plant functional traits to drought and salinity. A meta-analysis study

We aimed at exploring the plant functional traits whose responses to drought or salinity are altered by the presence of arbuscular mycorrhiza (AM). We performed a meta-analysis across 114 articles spanning 110 plant species or cultivars. We quantified the size effect of AM symbiosis on the stress response of several functional traits, using linear mixed model analysis (LMM). Correlation analysis between functional traits and total biomass responses to stresses were also performed through LMM. The literature search and further selection yielded seven functional traits, extracted from 114 laboratory studies, including 888 observations and 110 plant species/cultivars. Evidence for significant effects of predictor variables (type of stress, AM symbiosis and/or their interaction) on functional trait response were found for leaf area ratio (LAR), root mass fraction (RMF) and root-shoot (R:S) ratio. Our results provided evidence to accept the hypothesis that AM fungal inoculation may reduce the stress response of these plant functional traits by decreasing its magnitude. We also found a weak correlation between stress responses of these traits and total biomass variation. Although our literature search and data collection were intensive and our results robust, the scope of our conclusions is limited by the agronomical bias of plant species targeted by the meta-analysis. Further knowledge on non-cultivable plant species and better understanding of the mechanisms ruling resources allocation in plants would allow more generalised conclusions.

Viability of Pentadesma in reduced habitat ecosystems within two climatic regions with fruit harvesting

Habitat loss and harvesting of non-timber forest products (NTFPs) significantly affect the population dynamics. In this paper, we propose a general mathematical modelling approach incorporating the impact of habitat size reduction and non-lethal harvesting of NTFP on population dynamics. The model framework integrates experimental data of Pentadesma butyracea in Benin. This framework allows us to determine the rational non-lethal harvesting level and habitat size to ensure the stability of the plant ecosystem, and to study the impacts of distinct levels of humidity. We suggest non-lethal harvesting policies that maximize the economic benefit for local populations.

Molecular Phylogeography and Intraspecific Divergences in Siberian Wildrye (Elymus sibiricus L.) Wild Populations in China, Inferred From Chloroplast DNA Sequence and cpSSR Markers

A detailed understanding of the distribution and degree of genetic variation within a species is important for determining their evolutionary potential, which in return facilitates the development of efficient conservation strategies aimed at preserving adaptive genetic variation. As an important perennial, cool-season grass in temperate Eurasia, increasing attention has been paid to Siberian wildrye (Elymus sibiricus) due to its excellent ecological utilization value and forage production potential in China, particularly in the Qinghai-Tibet Plateau (QTP) regions. In this study, we applied two chloroplast (cp) genes (matK and rbcL), three cp spacer regions (trnY-GUA∼trnD-GUC, atpH∼atpF, and rps4∼trnT-UGU), and six cpSSR markers to the genetic and phylogenetic analysis of 137 wild E. sibiricus accessions from 23 natural populations that represent the main distribution regions in China. The results show the highest genetic diversity (h = 0.913) and haplotype richness (10 haplotypes) for the QTP population, which indicates QTP as the probable diversity center and geographic origin of E. sibiricus in China. Population divergence was high, indicating a significant phylogeographic structure together with a significantly higher N_st value (N_st > G_st, P < 0.05) at the species level, QTP+XJ (combined populations from QTP and Xinjiang), QTP+NC (combined populations from QTP and North China), and XJ+NC (combined populations from Xinjiang and North China) group levels, respectively. An expansion was revealed in the distributional range of E. sibiricus in China from paleo times up to the recent past, while a dramatic range of contraction was predicted for the near future. The predicted main limiting factor for the further spread of E. sibiricus is an increasing global mean temperature. We recommend that the combination of Es-cpDNA1 and Es-cpDNA3+4+5 can be used as effective markers for phylogenetic analysis and phylogeographical history analysis of E. sibiricus. These findings shed new light on the historical population dynamics of cold-season herbs in the QTP region and the north of China and are of great significance for the future establishment of protection and collection strategies for wild E. sibiricus germplasm.

Response of Iranian lizards to future climate change by poleward expansion, southern contraction, and elevation shifts

This study explores the relationships between recent Iranian lizard species distributions and the observed climate, as well as potential future distributions of species. For this purpose, an ensemble of seven algorithms was used to forecast the distributions of 30 species for the recent and future (2070) based on the averages of 14 global climate models under optimistic (RCP2.6) and pessimistic (RCP8.5) scenarios. Annual precipitation (n = 16) and annual mean temperature (n = 7) were identified as the most important variables in determining the distribution of 76.66% (23 out of 30) of the species. The consensus model predicts that the ranges of 83.33% of species (n = 25) have the potential to expand poleward at higher latitudes while preserving the majority of their recent distributions (except for four species). Furthermore, the ranges of the remaining species (n = 5) will be preserved at higher latitudes. However, they (n = 22) may contract slightly (n = 13) or excessively (n = 9) in the south of their distribution range at lower latitudes. These results indicate that species (N = 19) situated in mountainous areas such as the Zagros, Alborz, and Kopet Dagh may move or maintain their range at higher elevations as a result of future climate change. Finally, this study suggests that 30% of species (n = 9) may be threatened by future climate change and that they should be prioritized in conservation efforts.

Anthropogenic fragmentation increases risk of genetic decline in the threatened orchid Platanthera leucophaea

Protecting biodiversity requires an understanding of how anthropogenic changes impact the genetic processes associated with extinction risk. Studies of the genetic changes due to anthropogenic fragmentation have revealed conflicting results. This is likely due to the difficulty in isolating habitat loss and fragmentation, which can have opposing impacts on genetic parameters. The well-studied orchid, Platanthera leucophaea, provides a rich dataset to address this issue, allowing us to examine range-wide genetic changes. Midwestern and Northeastern United States. We sampled 35 populations of P. leucophaea that spanned the species' range and varied in patch composition, degree of patch isolation, and population size. From these populations we measured genetic parameters associated with increased extinction risk. Using this combined dataset, we modeled landscape variables and population metrics against genetic parameters to determine the best predictors of increased extinction risk. All genetic parameters were strongly associated with population size, while development and patch isolation showed an association with genetic diversity and genetic structure. Genetic diversity was lowest in populations with small census sizes, greater urbanization pressures (habitat loss), and small patch area. All populations showed moderate levels of inbreeding, regardless of size. Contrary to expectation, we found that critically small populations had negative inbreeding values, indicating non-random mating not typically observed in wild populations, which we attribute to selection for less inbred individuals. The once widespread orchid, Platanthera leucophaea, has suffered drastic declines and extant populations show changes in the genetic parameters associated with increased extinction risk, especially smaller populations. Due to the important correlation with risk and habitat loss, we advocate continued monitoring of population sizes by resource managers, while the critically small populations may need additional management to reverse genetic declines.

Plastic and quantitative genetic divergence mirror environmental gradients among wild, fragmented populations of Impatiens capensis

PREMISE

Habitat fragmentation generates molecular genetic divergence among isolated populations, but few studies have assessed phenotypic divergence and fitness in populations where the genetic consequences of habitat fragmentation are known. Phenotypic divergence could reflect plasticity, local adaptation, and/or genetic drift.

METHODS

We examined patterns and potential drivers of phenotypic divergence among 12 populations of jewelweed (Impatiens capensis) that show strong molecular genetic signals of isolation and drift among fragmented habitats. We measured morphological and reproductive traits in both maternal plants within natural populations and their self-fertilized progeny grown together in a common garden. We also quantified environmental divergence between home sites and the common garden.

RESULTS

Populations with less molecular genetic variation expressed less maternal phenotypic variation. Progeny in the common garden converged in phenotypes relative to their wild mothers but retained among-population differences in morphology, survival, and reproduction. Among-population phenotypic variance was 3-10× greater in home sites than in the common garden for 6 of 7 morphological traits measured. Patterns of phenotypic divergence paralleled environmental gradients in ways suggestive of adaptation. Progeny resembled their mothers less as the environmental distance between their home site and the common garden increased.

CONCLUSIONS

Despite strong molecular signatures of isolation and drift, phenotypic differences among these Impatiens populations appear to reflect both adaptive quantitative genetic divergence and plasticity. Quantifying the extent of local adaptation and plasticity and how these covary with molecular and phenotypic variation help us predict when populations may lose their adaptive capacity.

Importance of Thai macaque bioresources for biological research and human health

During the past century, macaque bioresources have provided remarkable scientific and biomedical discoveries related to the understanding of human physiology, neuroanatomy, reproduction, development, cognition, and pathology. Considerable progress has been made, and an urgent need has arisen to develop infrastructure and viable settings to meet the current global demand in research models during the so-called new normal after COVID-19 era. This review highlights the critical need for macaque bioresources and proposes the establishment of a designated primate research center to integrate research in primate laboratories for the rescue and rehabilitation of wild macaques. Key areas where macaque models have been and continue to be essential for advancing fundamental knowledge in biomedical and biological research are outlined. Detailed genetic studies on macaque bioresources of Thai origin can further facilitate the rapid pace of vaccine discovery.

Microbiome-mediated effects of habitat fragmentation on native plant performance

Habitat fragmentation is a leading cause of biodiversity and ecosystem function loss in the Anthropocene. Despite the importance of plant-microbiome interactions to ecosystem productivity, we have limited knowledge of how fragmentation affects microbiomes and even less knowledge of its consequences for microbial interactions with plants. Combining field surveys, microbiome sequencing, manipulative experiments, and random forest models, we investigated fragmentation legacy effects on soil microbiomes in imperiled pine rocklands, tested how compositional shifts across 14 fragmentation-altered soil microbiomes affected performance and resource allocation of three native plant species, and identified fragmentation-responding microbial families underpinning plant performance. Legacies of habitat fragmentation were associated with significant changes in microbial diversity and composition (across three of four community axes). Experiments showed plants often strongly benefited from the microbiome's presence, but fragmentation-associated changes in microbiome composition also significantly affected plant performance and resource allocation across all seven metrics examined. Finally, random forest models identified ten fungal and six bacterial families important for plant performance that changed significantly with fragmentation. Our findings not only support the existence of significant fragmentation effects on natural microbiomes, but also demonstrate for the first time that fragmentation-associated changes in microbiomes can have meaningful consequences for native plant performance and investment.

Morphological Variation in Scarlet Plume (Euphorbia fulgens Karw ex Klotzsch, Euphorbiaceae), an Underutilized Ornamental Resource of Mexico with Global Importance

Morphological variation is useful in conservation and genetic improvement programs. Euphorbia fulgens, a range-restricted local endemic species of Mexico, is used locally during the altars in the festivities of different saints and is also cultivated as an ornamental plant mainly in Europe. Thus, in the present study, morphological variation was evaluated in wild populations and cultivated populations. Characterization of 90 individuals from three wild populations (the only ones recorded to date) was done by measuring 30 morphological traits both vegetative and reproductive. Thereafter, seeds were collected, and established under greenhouse conditions, and 39 morphometric variables were evaluated in adult plants. An analysis of variance (ANOVA) was done for wild and cultivated groups independently, and when significant differences were found, Tukey's comparison of means was applied (p < 0.05). To identify the traits responsible for the differences between wild and cultivated groups, a linear discriminant analysis (LDA) was conducted. Morphological variation was found among wild populations, and this variation decreased in cultivated populations, mainly in reproductive structures. The LDA separated the wild populations from the cultivated groups, according to inflorescence length, petiole length/blade length ratio, and leaf roundness. The variables that determined the separation of individuals between wild and cultivated populations were cyme number, foliar Feret diameter, and inflorescence length, variables that can be important for breeding strategies and artificial selection.

The Genomic Processes of Biological Invasions: From Invasive Species to Cancer Metastases and Back Again

The concept of invasion is useful across a broad range of contexts, spanning from the fine scale landscape of cancer tumors up to the broader landscape of ecosystems. Invasion biology provides extraordinary opportunities for studying the mechanistic basis of contemporary evolution at the molecular level. Although the field of invasion genetics was established in ecology and evolution more than 50 years ago, there is still a limited understanding of how genomic level processes translate into invasive phenotypes across different taxa in response to complex environmental conditions. This is largely because the study of most invasive species is limited by information about complex genome level processes. We lack good reference genomes for most species. Rigorous studies to examine genomic processes are generally too costly. On the contrary, cancer studies are fortified with extensive resources for studying genome level dynamics and the interactions among genetic and non-genetic mechanisms. Extensive analysis of primary tumors and metastatic samples have revealed the importance of several genomic mechanisms including higher mutation rates, specific types of mutations, aneuploidy or whole genome doubling and non-genetic effects. Metastatic sites can be directly compared to primary tumor cell counterparts. At the same time, clonal dynamics shape the genomics and evolution of metastatic cancers. Clonal diversity varies by cancer type, and the tumors’ donor and recipient tissues. Still, the cancer research community has been unable to identify any common events that provide a universal predictor of “metastatic potential” which parallels findings in evolutionary ecology. Instead, invasion in cancer studies depends strongly on context, including order of events and clonal composition. The detailed studies of the behavior of a variety of human cancers promises to inform our understanding of genome level dynamics in the diversity of invasive species and provide novel insights for management.

Limited effect of a highway barrier on the genetic structure of a gypsum soil specialist

Background

Gypsum ecosystems are edaphic islands surrounded by a matrix that is inhospitable to gypsum soil plant specialists. These naturally fragmented landscapes are currently exacerbated due to man-made disturbances, jeopardising their valuable biodiversity. Concomitant action of other fragmentation drivers such as linear infrastructures may increase the already high threat to these specialists. Although some evidence suggest that gypsophytes are not evolutionary dead-ends and can respond to fragmentation by means of phenotypic plasticity, the simultaneous action of barriers to genetic flow can pose a severe hazard to their viability. Here, we evaluated the effect of a highway with heavy traffic on the genetic flow and diversity in the species Lepidium subulatum, a dominant Iberian shrubby gypsophyte.

Methods

We tested the possible existence of bottlenecks, and estimated the genetic diversity, gene flow and genetic structure in the remnant populations, exploring in detail the effect of a highway as a possible barrier.

Results

Results showed variability in genetic diversity, migrants and structure. The highway had a low impact on the species since populations can retain high levels of genetic diversity and genetic parameter, like F_ST and F_IS, did not seem to be affected. The presence of some level of genetic flow in both sides along the highway could explain the relatively high genetic diversity in the habitat remnants.

Discussion

Natural fragmentation and their exacerbation by agriculture and linear infrastructures seem to be negligible for this species and do not limit its viability. The biological features, demographic dynamics and population structures of gypsum species seem to be a valuable, adaptive pre-requisite to be a soil specialist and to maintain its competitiveness with other species in such adverse stressful conditions.

Habitat fragmentation and population features differently affect fruit predation, fecundity and offspring performance in a non-specialist gypsum plant

The effects of habitat fragmentation on plant populations are complex, as it might disrupt many ecological processes, including plant reproduction and plant-animal interactions. Gypsum specialist plants may be resilient to fragmentation due to their evolutionary history in fragmented landscapes, but the effects on non-specialist plants occurring in gypsum are unknown. We conducted a study focusing on different aspects of the reproductive cycle of Astragalus incanus subsp. incanus, a plant facultatively linked to gypsum soils. We focused on plant fecundity and pre-dispersal predation, obtained from field observations, and offspring performance, assessed in a common garden. Beyond fragment size and connectivity, we also considered habitat quality, population size and density and plant size as predictors. Fragment size and connectivity had no effect on plant fecundity, but jointly determined fruit predation, while fragment size was positively related to offspring growth. Population density, rather than population size, had a positive effect on predation but negatively affected plant fecundity and offspring performance. Habitat quality reduced both plant fecundity and predation incidence. In this non-specialist species, habitat fragmentation, population features and habitat quality affect different facets of plant performance. Predation was the only process clearly affected by fragmentation variables, fecundity mainly depended on population features and offspring performance and was better explained by mother plant identity. Our results show the need to consider habitat and population features together with fragment size and connectivity in order to assess the effects of fragmentation. Importantly, these effects can involve different aspects of plant reproduction, including plant-animal interactions.

Low genetic diversity indicating the threatened status of Rhizophora apiculata (Rhizophoraceae) in Malaysia: declined evolution meets habitat destruction

Worldwide, many mangrove species are experiencing significant population declines, including Rhizophora apiculata, which is one of the most widespread and economically important species in tropical Asia. In Malaysia, there has been an alarming decline in R. apiculata populations driven primarily by anthropogenic activities. However, the lack of genetic and demographic information on this species has hampered local efforts to conserve it. To address these gaps, we generated novel genetic information for R. apiculata, based on 1,120 samples collected from 39 natural populations in Peninsular Malaysia. We investigated its genetic diversity and genetic structure with 19 transcriptome and three nuclear microsatellite markers. Our analyses revealed a low genetic diversity (mean H_e: 0.352) with significant genetic differentiation (F_ST: 0.315) among populations of R. apiculata. Approximately two-third of the populations showed significant excess of homozygotes, indicating persistent inbreeding which might be due to the decrease in population size or fragmentation. From the cluster analyses, the populations investigated were divided into two distinct clusters, comprising the west and east coasts of Peninsular Malaysia. The western cluster was further divided into two sub-clusters with one of the sub-clusters showing strong admixture pattern that harbours high levels of genetic diversity, thus deserving high priority for conservation.

Genome-wide genotyping estimates mating system parameters and paternity in the island species Tolpis succulenta

PREMISE

The mating system has profound consequences, not only for ecology and evolution, but also for the conservation of threatened or endangered species. Unfortunately, small populations are difficult to study owing to limits on sample size and genetic marker diversity. Here, we estimated mating system parameters in three small populations of an island plant using genomic genotyping. Although self-incompatible (SI) species are known to often set some self-seed, little is known about how "leaky SI" affects selfing rates in nature or the role that multiple paternity plays in small populations.

METHODS

We generalized the BORICE mating system program to determine the siring pattern within maternal families. We applied this algorithm to maternal families from three populations of Tolpis succulenta from Madeira Island and genotyped the progeny using RADseq. We applied BORICE to estimate each individual offspring as outcrossed or selfed, the paternity of each outcrossed offspring, and the level of inbreeding of each maternal plant.

RESULTS

Despite a functional self-incompatibility system, these data establish T. succulenta as a pseudo-self-compatible (PSC) species. Two of 75 offspring were strongly indicated as products of self-fertilization. Despite selfing, all adult maternal plants were fully outbred. There was high differentiation among and low variation within populations, consistent with a history of genetic isolation of these small populations. There were generally multiple sires per maternal family. Twenty-two percent of sib contrasts (between outcrossed offspring within maternal families) shared the same sire.

CONCLUSIONS

Genome-wide genotyping, combined with appropriate analytical methods, enables estimation of mating system and multiple paternity in small populations. These data address questions about the evolution of reproductive traits and the conservation of threatened populations.

Meta-analysis of the differential effects of habitat fragmentation and degradation on plant genetic diversity

Genetic diversity is a key factor for population survival and evolution. However, anthropogenic habitat disturbance can erode it, making populations more prone to extinction. Aiming to assess the global effects of habitat disturbance on plant genetic variation, we conducted a meta-analysis based on 92 case studies obtained from published literature. We compared the effects of habitat fragmentation and degradation on plant allelic richness and gene diversity (equivalent to expected heterozygosity) and tested whether such changes are sensitive to different life-forms, life spans, mating systems, and commonness. Anthropogenic disturbance had a negative effect on allelic richness, but not on gene diversity. Habitat fragmentation had a negative effect on genetic variation, whereas habitat degradation had no effect. When we examined the individual effects in fragmented habitats, allelic richness and gene diversity decreased, but this decrease was strongly dependent on certain plant traits. Specifically, common long-lived trees and self-incompatible species were more susceptible to allelic richness loss. Conversely, gene diversity decreased in common short-lived species (herbs) with self-compatible reproduction. In a wider geographical context, tropical plant communities were more sensitive to allelic richness loss, whereas temperate plant communities were more sensitive to gene diversity loss. Our synthesis showed complex responses to habitat disturbance among plant species. In many cases, the absence of effects could be the result of the time elapsed since the disturbance event or reproductive systems favoring self-pollination, but attention must be paid to those plant species that are more susceptible to losing genetic diversity, and appropriate conservation should be actions taken.

High differentiation in functional traits but similar phenotypic plasticity in populations of a soil specialist along a climatic gradient

BACKGROUND AND AIMS

Plants experiencing contrasting environmental conditions may accommodate such heterogeneity by expressing phenotypic plasticity, evolving local adaptation or a combination of both. We investigated patterns of genetic differentiation and plasticity in response to drought in populations of the gypsum specialist Lepidium subulatum.

METHODS

We created an outdoor common garden with rain exclusion structures using 60 maternal progenies from four distinct populations that substantially differ in climatic conditions. We characterized fitness, life history and functional plasticity in response to two contrasting treatments that realistically reflect soil moisture variation in gypsum habitats. We also assessed neutral genetic variation and population structure using microsatellite markers.

KEY RESULTS

In response to water stress, plants from all populations flowered earlier, increased allocation to root tissues and advanced leaf senescence, consistent with a drought escape strategy. Remarkably, these probably adaptive responses were common to all populations, as shown by the lack of population × environment interaction for almost all functional traits. This generally common pattern of response was consistent with substantial neutral genetic variation and large differences in population trait means. However, such population-level trait variation was not related to climatic conditions at the sites of origin.

CONCLUSIONS

Our results show that, rather than ecotypes specialized to local climatic conditions, these populations are composed of highly plastic, general-purpose genotypes in relation to climatic heterogeneity. The strikingly similar patterns of plasticity among populations, despite substantial site of origin differences in climate, suggest past selection on a common norm of reaction due to similarly high levels of variation within sites. It is thus likely that plasticity will have a prevalent role in the response of this soil specialist to further environmental change.

Narrow gene pool can threaten the survival of Calamus nagbettai R. R. Fernald & Dey: a highly, endemic dioecious rattan species in the Western Ghats of India

Rattans, the spiny climbing palms of Arecaceae (Palmae) family exhibit high endemism to the biodiversity hot spots in India. Of the five rattan genera, Calamus is the only genus found in peninsular India with 15 of 21 species, endemic to the Western Ghats. The extensive utilization of rattans owing to their strength, durability and huge demand has resulted in depletion of their natural resources. Of the 15 endemic species, C. nagbettai is the most affected species on account of endemism, low population size and restricted distribution with fragmented populations. The present study revealed high amount of genetic diversity in the surviving scattered populations of the species using microsatellite markers. High gene flow (N_m = 1.498) observed across the populations resulted in low genetic differentiation (14%). A clear genetic admixture could be seen in Kerala as well as one of the Karnataka's populations while the remaining two populations were genetically distinct. UPGMA, PCoA and STRUCTURE analyses showed significantly different genetic composition in Kerala population compared to other populations. Kerala and Karnataka populations of C. nagbettai were also unique in their genetic structure and allelic composition. Therefore, effective management and conservation strategies have to be implemented to preserve the rarealleles with adaptive potential to protect this economically valuable Calamus species from endangerment. Over exploitation, low seed set and poor regeneration, as well as habitat fragmentation can further threaten the survival of this endemic, narrowly distributed dioecious rattan species in the Western Ghats region.

Herbivore corridors sustain genetic footprint in plant populations: a case for Spanish drove roads

Habitat fragmentation is one of the greatest threats to biodiversity conservation and ecosystem productivity mediated by direct human impact. Its consequences include genetic depauperation, comprising phenomena such as inbreeding depression or reduction in genetic diversity. While the capacity of wild and domestic herbivores to sustain long-distance seed dispersal has been proven, the impact of herbivore corridors in plant population genetics remains to be observed. We conducted this study in the Conquense Drove Road in Spain, where sustained use by livestock over centuries has involved transhumant herds passing twice a year en route to winter and summer pastures. We compared genetic diversity and inbreeding coefficients of Plantago lagopus populations along the drove road with populations in the surrounding agricultural matrix, at varying distances from human settlements. We observed significant differences in coefficients of inbreeding between the drove road and the agricultural matrix, as well as significant trends indicative of higher genetic diversity and population nestedness around human settlements. Trends for higher genetic diversity along drove roads may be present, although they were only marginally significant due to the available sample size. Our results illustrate a functional landscape with human settlements as dispersal hotspots, while the findings along the drove road confirm its role as a pollinator reservoir observed in other studies. Drove roads may possibly also function as linear structures that facilitate long-distance dispersal across the agricultural matrix, while local P. lagopus populations depend rather on short-distance seed dispersal. These results highlight the role of herbivore corridors for conserving the migration capacity of plants, and contribute towards understanding the role of seed dispersal and the spread of invasive species related to human activities.

Assessment of genetic variation among wild Alpinia nigra (Zingiberaceae) population: an approach based on molecular phylogeny

Genetic structure was evaluated among wild Alpinia nigra (Gaertn.) B.L. Burtt, populations. The information of genetic relatedness was developed using random amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR) and barcoding loci (plastid and mitochondrial). The order (high to low) of Shannon's information index (I) and Nei's gene diversity (h) from the populations was: "IIT Guwahati" > "Amingaon" > "Saraighat". Genetic diversity decreased and genetic differentiation increased among the three populations. We observed no isolation by distance thus lower amount of gene flow was observed. Narrow range of genetic distance among the three populations and appearance of two distinct clusters strengthened the geographical isolation in dendrogram and principal component analysis. No mutation among the three populations was observed for seven plastid loci and two mitochondrial tested suggesting the taxonomic homogeneity. The phylogeny based on nine barcoding loci supported our observation that individuals of IIT Guwahati were partially isolated from the outside populations. Our study will provide a backbone for developing strategies to resist habitat fragmentation of Zingiberaceous plants.