Assessing the benefits and risks of translocations in changing environments: a genetic perspective

Crossing borders - European forest reproductive material moving in trade

Forest reproductive material (FRM) is constantly traded between European countries, but bilateral trade statistics on a European scale are limited. For the first time we analysed national datasets according Council Directiv 1999/105/EC for the tree species Picea abies, Pinus sylvestris, P. pinaster, Fagus sylvatica, Fraxinus excelsior, Quercus robur, Q. rubra, and Q. petraea. Based on the period 2004-2014 we (i) quantified the amount and identified European FRM trade and production routes, (ii) applied a gravity model of economic trade to examine the determinants of trade, (iii) discussed the putative genetic impact of transferred FRM on native tree populations, and (iv) considered legislation and documentation processes to their compliance, purpose, and benefit in producing data relevant to sustainable forest management. On average, 30 million plants and 400,000 kg seeds were annually traded. About 85% of traded seedlings were Norway spruce. Coniferous FRM trade is dominated by Scandinavian and Baltic countries, while broad-leaved species are extensively traded in Central Europe. FRM trade and production are interconnected on a multinational level, and besides domestic FRM, most countries are also trading with foreign material. The results of the gravity model indicate that among other significant factors the bilateral trade is driven by geographical distance, currency, and forestry contribution to the domestic gross product. As no detailed data on seed transfer were made available by most countries, the total FRM transfer is biased and probably underestimated.

Distinguishing recent dispersal from historical genetic connectivity in the coastal California gnatcatcher

Habitat loss and fragmentation are primary threats to biodiversity worldwide. We studied the impacts of habitat loss and fragmentation on genetic connectivity and diversity among local aggregations of the California gnatcatcher (Polioptila californica californica) across its U.S. range. With a dataset of 268 individuals genotyped at 19 microsatellite loci, we analyzed genetic structure across the range using clustering analyses, exact tests for population differentiation, and a pedigree analysis to examine the spatial distribution of first-order relatives throughout the study area. In addition, we developed a habitat suitability model and related percent suitable habitat to genetic diversity indices within aggregations at two spatial scales. We detected a single genetic cluster across the range, with weak genetic structure among recently geographically isolated aggregations in the northern part of the range. The pedigree analysis detected closely related individuals across disparate aggregations and across large geographic distances in the majority of the sampled range, demonstrating that recent long-distance dispersal has occurred within this species. Genetic diversity was independent of suitable habitat at a local 5-km scale, but increased in a non-linear fashion with habitat availability at a broader, 30-km scale. Diversity declined steeply when suitable habitat within 30-km fell below 10%. Together, our results suggest that California gnatcatchers retain genetic connectivity across the majority of the current distribution of coastal sage scrub fragments, with the exception of some outlying aggregations. Connectivity may help support long-term persistence under current conservation and management strategies. However, emerging structure among more remote aggregations and associations between available habitat and genetic diversity also suggest that continued loss of habitat could threaten diversity and connectivity in the future.

Conserving adaptive potential: lessons from Tasmanian devils and their transmissible cancer

Maintenance of adaptive genetic variation has long been a goal of management of natural populations, but only recently have genomic tools allowed identification of specific loci associated with fitness-related traits in species of conservation concern. This raises the possibility of managing for genetic variation directly relevant to specific threats, such as those due to climate change or emerging infectious disease. Tasmanian devils (Sarcophilus harrisii) face the threat of a transmissible cancer, devil facial tumor disease (DFTD), that has decimated wild populations and led to intensive management efforts. Recent discoveries from genomic and modeling studies reveal how natural devil populations are responding to DFTD, and can inform management of both captive and wild devil populations. Notably, recent studies have documented genetic variation for disease-related traits and rapid evolution in response to DFTD, as well as potential mechanisms for disease resistance such as immune response and tumor regression in wild devils. Recent models predict dynamic persistence of devils with or without DFTD under a variety of modeling scenarios, although at much lower population densities than before DFTD emerged, contrary to previous predictions of extinction. As a result, current management that focuses on captive breeding and release for maintaining genome-wide genetic diversity or demographic supplementation of populations could have negative consequences. Translocations of captive devils into wild populations evolving with DFTD can cause outbreeding depression and/or increases in the force of infection and thereby the severity of the epidemic, and we argue that these risks outweigh any benefits of demographic supplementation in wild populations. We also argue that genetic variation at loci associated with DFTD should be monitored in both captive and wild populations, and that as our understanding of DFTD-related genetic variation improves, considering genetic management approaches to target this variation is warranted in developing conservation strategies for Tasmanian devils.

Targeted gene flow and rapid adaptation in an endangered marsupial

Targeted gene flow is an emerging conservation strategy. It involves translocating individuals with favorable genes to areas where they will have a conservation benefit. The applications for targeted gene flow are wide-ranging but include preadapting native species to the arrival of invasive species. The endangered carnivorous marsupial, the northern quoll (Dasyurus hallucatus), has declined rapidly since the introduction of the cane toad (Rhinella marina), which fatally poisons quolls that attack them. There are, however, a few remaining toad-invaded quoll populations in which the quolls survive because they know not to eat cane toads. It is this toad-smart behavior we hope to promote through targeted gene flow. For targeted gene flow to be feasible, however, toad-smart behavior must have a genetic basis. To assess this, we used a common garden experiment, comparing offspring from toad-exposed and toad-naïve parents raised in identical environments, to determine whether toad-smart behavior is heritable. Offspring from toad-exposed populations were substantially less likely to eat toads than those with toad-naïve parents. Hybrid offspring showed similar responses to quolls with 2 toad-exposed parents, indicating the trait may be dominant. Together, these results suggest a heritable trait and rapid adaptive response in a small number of toad-exposed populations. Although questions remain about outbreeding depression, our results are encouraging for targeted gene flow. It should be possible to introduce toad-smart behavior into soon to be affected quoll populations.

The genetic legacy of 50 years of desert bighorn sheep translocations

Conservation biologists have increasingly used translocations to mitigate population declines and restore locally extirpated populations. Genetic data can guide the selection of source populations for translocations and help evaluate restoration success. Bighorn sheep (Ovis canadensis) are a managed big game species that suffered widespread population extirpations across western North America throughout the early 1900s. Subsequent translocation programs have successfully re-established many formally extirpated bighorn herds, but most of these programs pre-date genetically informed management practices. The state of Nevada presents a particularly well-documented case of decline followed by restoration of extirpated herds. Desert bighorn sheep (O. c. nelsoni) populations declined to less than 3,000 individuals restricted to remnant herds in the Mojave Desert and a few locations in the Great Basin Desert. Beginning in 1968, the Nevada Department of Wildlife translocated ~2,000 individuals from remnant populations to restore previously extirpated areas, possibly establishing herds with mixed ancestries. Here, we examined genetic diversity and structure among remnant herds and the genetic consequences of translocation from these herds using a genotyping-by-sequencing approach to genotype 17,095 loci in 303 desert bighorn sheep. We found a signal of population genetic structure among remnant Mojave Desert populations, even across geographically proximate mountain ranges. Further, we found evidence of a genetically distinct, potential relict herd from a previously hypothesized Great Basin lineage of desert bighorn sheep. The genetic structure of source herds was clearly reflected in translocated populations. In most cases, herds retained genetic evidence of multiple translocation events and subsequent admixture when founded from multiple remnant source herds. Our results add to a growing literature on how population genomic data can be used to guide and monitor restoration programs.

A multidisciplinary approach to inform assisted migration of the restricted rainforest tree, Fontainea rostrata

Assisted migration can aid in the conservation of narrowly endemic species affected by habitat loss, fragmentation and climate change. Here, we employ a multidisciplinary approach by examining the population genetic structure of a threatened, dioecious rainforest tree of the subtropical notophyll vine forests of eastern Australia, Fontainea rostrata, and its potential requirements for population enhancement and translocation to withstand the effects of anthropogenic fragmentation and climate change. We used microsatellite markers to gain an understanding of the way genetic diversity is partitioned within and among the nine extant populations of F. rostrata identified in this study. We combined the results with species distribution modelling to identify populations vulnerable to possible future range shifts based on climate change projections. We found regional differences between the species’ main distribution in the south and a disjunct northern population cluster (F_RT = 0.074, F_SR = 0.088, F_ST = 0.155), in mean allelic richness (A_R = 2.77 vs 2.33, p < 0.05), expected heterozygosity (H_E = 0.376 vs 0.328), and inbreeding (F = 0.116 vs 0.219). Species distribution models predicted that while southern populations of F. rostrata are likely to persist for the next 50 years under the RCP6.0 climate change scenario, with potential for a small-scale expansion to the south-east, the more highly inbred and less genetically diverse northern populations will come under increasing pressure to expand southwards as habitat suitability declines. Given the species’ genetic structure and with the aim to enhance genetic diversity and maximise the likelihood of reproductive success, we recommend that plant reintroductions to supplement existing populations should be prioritised over translocation of the species to new sites. However, future conservation efforts should be directed at translocation to establish new sites to increase population connectivity, focussing particularly on habitat areas identified as persisting under conditions of climate change.

How many came home? Evaluating ex situ conservation of green turtles in the Cayman Islands

Ex situ management is an important conservation tool that allows the preservation of biological diversity outside natural habitats while supporting survival in the wild. Captive breeding followed by re-introduction is a possible approach for endangered species conservation and preservation of genetic variability. The Cayman Turtle Centre Ltd was established in 1968 to market green turtle (Chelonia mydas) meat and other products and replenish wild populations, thought to be locally extirpated, through captive breeding. We evaluated the effects of this re-introduction programmme using molecular markers (13 microsatellites, 800-bp D-loop and simple tandem repeat mitochondrial DNA sequences) from captive breeders (N = 257) and wild nesting females (N = 57) (sampling period: 2013-2015). We divided the captive breeders into three groups: founders (from the original stock), and then two subdivisions of F₁ individuals corresponding to two different management strategies, cohort 1995 ("C1995") and multicohort F₁ ("MCF1"). Loss of genetic variability and increased relatedness was observed in the captive stock over time. We found no significant differences in diversity among captive and wild groups, and similar or higher levels of haplotype variability when compared to other natural populations. Using parentage and sibship assignment, we determined that 90% of the wild individuals were related to the captive stock. Our results suggest a strong impact of the re-introduction programmme on the present recovery of the wild green turtle population nesting in the Cayman Islands. Moreover, genetic relatedness analyses of captive populations are necessary to improve future management actions to maintain genetic diversity in the long term and avoid inbreeding depression.

The Genomic Footprints of the Fall and Recovery of the Crested Ibis

Human-induced environmental change and habitat fragmentation pose major threats to biodiversity and require active conservation efforts to mitigate their consequences. Genetic rescue through translocation and the introduction of variation into imperiled populations has been argued as a powerful means to preserve, or even increase, the genetic diversity and evolutionary potential of endangered species [1-4]. However, factors such as outbreeding depression [5, 6] and a reduction in available genetic diversity render the success of such approaches uncertain. An improved evaluation of the consequence of genetic restoration requires knowledge of temporal changes to genetic diversity before and after the advent of management programs. To provide such information, a growing number of studies have included small numbers of genomic loci extracted from historic and even ancient specimens [7, 8]. We extend this approach to its natural conclusion, by characterizing the complete genomic sequences of modern and historic population samples of the crested ibis (Nipponia nippon), an endangered bird that is perhaps the most successful example of how conservation effort has brought a species back from the brink of extinction. Though its once tiny population has today recovered to >2,000 individuals [9], this process was accompanied by almost half of ancestral loss of genetic variation and high deleterious mutation load. We furthermore show how genetic drift coupled to inbreeding following the population bottleneck has largely purged the ancient polymorphisms from the current population. In conclusion, we demonstrate the unique promise of exploiting genomic information held within museum samples for conservation and ecological research.

How many and when? Optimising targeted gene flow for a step change in the environment

Targeted gene flow is an emerging conservation strategy that involves introducing individuals with particular traits to places where these traits are of benefit. One obvious application is to adapt a recipient population to a known threat, but questions remain as to how best to achieve this. Here, we vary timing and size of the introduction to maximise our objective - survival of the recipient population's genome. We explore a generic population model as well as a specific example - the northern quoll, an Australian marsupial predator threatened by the toxic cane toad. We reveal a trade-off between preserving the recipient genome and reducing population extinction risk, but key management levers can often optimise this so that nearly 100% of the recipient population's genome is preserved. Any action was better than none but the size of the benefit was sensitive to outbreeding depression, recombination rate, and the timing and size of the introduction.

Measures of effective population size in sea otters reveal special considerations for wide-ranging species

Conservation genetic techniques and considerations of the evolutionary potential of a species are increasingly being applied to species conservation. For example, effective population size (N e) estimates are useful for determining the conservation status of species, yet accurate estimates of current N e remain difficult to obtain. The effective population size can contribute to setting federal delisting criteria, as was done for the southern sea otter (Enhydra lutris nereis). After being hunted to near extinction during the North Pacific fur trade, the southern sea otter has recovered over part of its former range, but remains at relatively low numbers, making it desirable to obtain accurate and consistent estimates of N e. Although theoretical papers have compared the validity of several methods, comparisons of estimators using empirical data in applied conservation settings are limited. We combined thirteen years of demographic and genetic data from 1,006 sea otters to assess multiple N e estimators, as well as temporal trends in genetic diversity and population genetic structure. Genetic diversity was low and did not increase over time. There was no evidence for distinct genetic units, but some evidence for genetic isolation by distance. In particular, estimates of N e based on demographic data were much larger than genetic estimates when computed for the entire range of the population, but were similar at smaller spatial scales. The discrepancy between estimates at large spatial scales could be driven by cryptic population structure and/or individual differences in reproductive success. We recommend the development of new delisting criteria for the southern sea otter. We advise the use of multiple estimates of N e for other wide-ranging species, species with overlapping generations, or with sex-biased dispersal, as well as the development of improved metrics of genetic assessments of populations.

The extended consequences of genetic conductivity: Mating distance affects community phenotypes in Norway spruce

Anthropogenic landscape-level alterations such as habitat fragmentation and long distance translocation of genetic material are currently altering the genetic connectivity and structure of forest tree populations globally. As the susceptibility of individual trees to dependent organisms is often genetically determined, it is possible that these genetic changes may extend beyond individuals to affect associated communities. To test this, we examined how variation in crossing distance among the progeny of 18 controlled crosses of Norway spruce (Picea abies) populations occurring across central Sweden affected chemical defense, and subsequently, a small community of galling Adelges aphids infecting planted trees at two common garden trails. Although crossing distance did not influence growth, vitality or reproduction in the studied population, it did influence the expression of one candidate defensive chemical compound, apigenin, which was found in higher concentrations within outcrossed trees. We also show that this variation in apigenin induced by crossing distance correlated with susceptibility to one member of the galling community but not the other. Furthermore, the effect of crossing distance on galling communities and the general susceptibility of Norway spruce to infection also varied with environment. Specifically, in the more benign environment, inbred trees suffered greater gall infection than outcrossed trees, which is contrary to general predictions that the effects of inbreeding should be more pronounced in harsher environments. These findings suggest that the effects of variation in crossing distance in forest trees can extend beyond the individual to influence whole communities.

Climate-based seed transfer of a widespread shrub: population shifts, restoration strategies, and the trailing edge

Genetic resources have to be managed appropriately to mitigate the impact of climate change. For many wildland plants, conservation will require knowledge of the climatic factors affecting intraspecific genetic variation to minimize maladaptation. Knowledge of the interaction between traits and climate can focus management resources on vulnerable populations, provide guidance for seed transfer, and enhance fitness and resilience under changing climates. In this study, traits of big sagebrush (Artemisia tridentata) were examined among common gardens located in different climates. We focus on two subspecies, wyomingensis and tridentata, that occupy the most imperiled warm-dry spectrum of the sagebrush biome. Populations collected across the sagebrush biome were recorded for flower phenology and survival. Mixed-effects models examined each trait to evaluate genetic variation, environmental effects, and adaptive breadth of populations. Climate variables derived from population-source locations were significantly associated with these traits (P < 0.0001), explaining 31% and 11% of the flower phenology and survival variation, respectively. To illustrate our model and assess variability in prediction, we examine fixed and focal point seed transfer approaches to map contemporary and climate model ensemble projections in two different regions of the sagebrush biome. A comparison of seed transfer areas predicts that populations from warmer climates become more prevalent, replacing colder-adapted populations by mid-century. However, these warm-adapted populations are often located along the trailing edge, margins of the species range predicted to be lost due to a contraction of the climatic niche. Management efforts should focus on the collection and conservation of vulnerable populations and prudent seed transfer to colder regions where these populations are projected to occur by mid-century. Our models provide the foundation to develop an empirical, climate-based seed transfer system for current and future restoration of big sagebrush.

Demographic histories of three predatory lady beetles reveal complex patterns of diversity and population size change in the United States

Predatory lady beetles (Coccinellidae) contribute to biological control of agricultural pests, however, multiple species frequently compete for similar resources in the same environment. Numerous studies have examined ecological interactions among the native North American convergent lady beetle (Hippodamia convergens) and two introduced species, the seven-spotted lady beetle (Coccinella septempunctata) and the Asian lady beetle (Harmonia axyridis), in agricultural fields and described multiyear population dynamics. However, the evolutionary dynamics of these interacting species of predatory beetles are uncharacterized. We utilize publicly available multilocus genotype data from geographically disjunct populations of these three species to estimate demography across North American populations. Coalescent analyses reveal (1) a recent (∼4-5 years) decline (>12 fold) in microsatellite effective population size of H. convergens, while expanding (mutation scaled growth rate in 1/u generations = 2910, SD = 362) over evolutionary time scales, (2) a massive (>150 fold), and very recent, effective population size decline in Ha. axyridis, and (3) population size growth (mutation scaled growth rate = 997, SD = 60) over recent and evolutionary time scales in C. septempunctata. Although these estimates are based on genetic data with different mutation rates and patterns of inheritance (mitochondrial versus nuclear), these dynamic and differing population size histories are striking. Further studies of the interactions of these predatory lady beetles in the field are thus warranted to explore the consequences of population size change and biological control activities for evolutionary trajectories in North America.

Sex-specific effects of outbreeding on offspring quality in pike (Esox lucius)

Intraspecific genetic admixture occurs when previously separated populations within a species start interbreeding, and it can have either positive, negative, or neutral effects on reproductive performance. As there currently is no reliable predictor for the outcome of admixture, an increased knowledge about admixture effects in different species and populations is important to increase the understanding about what determines the response to admixture. We tested for effects of admixture on F1 offspring quality in three subpopulations of pike (Esox lucius). Gametes were collected in the field, and eggs from each female were experimentally fertilized with milt from a male from each population (one "pure" and two "admixed" treatments). Three offspring quality measures (hatching success, fry survival, and fry length) were determined and compared between (a) pure and admixed population combinations and (b) the sex-specific treatments within each admixed population combination (based on the origin of the male and female, respectively). The results suggested that although there were no overall effects of admixture on offspring quality, the consequences for a given population combination could be sex-specific and thus differ depending on which of the parents originated from one or the other population. All offspring quality traits were influenced by both maternal ID and paternal ID. Sex- and individual-specific effects can have implications for dispersal behavior and gene flow between natural populations, and are important to consider in conservation efforts.

Augmenting the conservation value of rehabilitated wildlife by integrating genetics and population modeling in the post-rehabilitation decision process

Insular populations are particularly vulnerable to the effects of stochastic events, epidemics, and loss of genetic diversity due to inbreeding and genetic drift. The development of successful management options will require accurate baseline data, establishment of clear objectives, and finally monitoring and implementation of corrective measures, if and when required. This study assessed management options for the genetic rehabilitation of highly inbred woylies obtained from wildlife rehabilitation centers. The study generated genetic data for the woylie Bettongia penicillata from a conservation reserve and calculated measures of genetic diversity and individual relatedness. These data were fed into a population viability analysis (PVA) to test genetic outcomes in relation to different management actions. We demonstrated that a careful selection of the founder cohort produced a population with an expected heterozygosity of ∼70% for a window of approximately 10 years. A proposal to increase the size of the reserve available to the colony was shown to almost double the time at which the colony would retain heterozygosity levels of ≥ 70%. Additionally, developing a regular program of supplementation of unrelated woylies would result in a further improvement in their genetic value. This study demonstrated how the application of molecular techniques in combination with PVA can be beneficial for the management of rehabilitated wildlife otherwise considered of little conservation value. This approach can be applied to the management of breeding programs, but also to small, closed populations such as those found on islands, fenced enclosures, insurance populations, and in zoological collections.

Understanding managers' and scientists' perspectives on opportunities to achieve more evolutionarily enlightened management in conservation

Despite wide acceptance that conservation could benefit from greater attention to principles and processes from evolutionary biology, little attention has been given to quantifying the degree to which relevant evolutionary concepts are being integrated into management practices. There has also been increasing discussion of the potential reasons for a lack of evolutionarily enlightened management, but no attempts to understand the challenges from the perspective of those making management decisions. In this study, we asked conservation managers and scientists for their views on the importance of a range of key evolutionary concepts, the degree to which these concepts are being integrated into management, and what would need to change to support better integration into management practices. We found that while managers recognize the importance of a wide range of evolutionary concepts for conservation outcomes, they acknowledge these concepts are rarely incorporated into management. Managers and scientists were in strong agreement about the range of barriers that need to be overcome, with a lack of knowledge reported as the most important barrier to better integration of evolutionary biology into conservation decision-making. Although managers tended to be more focused on the need for more training in evolutionary biology, scientists reported greater engagement between managers and evolutionary biologists as most important to achieve the necessary change. Nevertheless, the challenges appear to be multifaceted, and several are outside the control of managers, suggesting solutions will need to be multidimensional.

Reintroduction of freshwater macroinvertebrates: challenges and opportunities

Species reintroductions - the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population - have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has been devoted to the reintroduction of invertebrates into restored freshwater habitats. Yet, reintroductions may improve restoration outcomes in regions where impoverished regional species pools limit the self-recolonisation of restored freshwaters. We review the available literature on macroinvertebrate reintroductions, focusing on identifying the intrinsic and extrinsic factors that determine their success or failure. Our study reveals that freshwater macroinvertebrate reintroductions remain rare, are often published in the grey literature and, of the attempts made, approximately one-third fail. We identify life-cycle complexity and remaining stressors as the two factors most likely to affect reintroduction success, illustrating the unique challenges of freshwater macroinvertebrate reintroductions. Consideration of these factors by managers during the planning process and proper documentation - even if a project fails - may increase the likelihood of successful outcomes in future reintroduction attempts of freshwater macroinvertebrates.

An experimental test of alternative population augmentation scenarios

Human land use is fragmenting habitats worldwide and inhibiting dispersal among previously connected populations of organisms, often leading to inbreeding depression and reduced evolutionary potential in the face of rapid environmental change. To combat this augmentation of isolated populations with immigrants is sometimes used to facilitate demographic and genetic rescue. Augmentation with immigrants that are genetically and adaptively similar to the target population effectively increases population fitness, but if immigrants are very genetically or adaptively divergent, augmentation can lead to outbreeding depression. Despite well-cited guidelines for the best practice selection of immigrant sources, often only highly divergent populations remain, and experimental tests of these riskier augmentation scenarios are essentially nonexistent. We conducted a mesocosm experiment with Trinidadian guppies (Poecilia reticulata) to test the multigenerational demographic and genetic effects of augmenting 2 target populations with 3 types of divergent immigrants. We found no evidence of demographic rescue, but we did observe genetic rescue in one population. Divergent immigrant treatments tended to maintain greater genetic diversity, abundance, and hybrid fitness than controls that received immigrants from the source used to seed the mesocosms. In the second population, divergent immigrants had a slightly negative effect in one treatment, and the benefits of augmentation were less apparent overall, likely because this population started with higher genetic diversity and a lower reproductive rate that limited genetic admixture. Our results add to a growing consensus that gene flow can increase population fitness even when immigrants are more highly divergent and may help reduce uncertainty about the use of augmentation in conservation.

Parallel genetic adaptation across environments differing in mode of growth or resource availability

Evolution experiments have demonstrated high levels of genetic parallelism between populations evolving in identical environments. However, natural populations evolve in complex environments that can vary in many ways, likely sharing some characteristics but not others. Here, we ask whether shared selection pressures drive parallel evolution across distinct environments. We addressed this question in experimentally evolved populations founded from a clone of the bacterium Burkholderia cenocepacia. These populations evolved for 90 days (approximately 600 generations) under all combinations of high or low carbon availability and selection for either planktonic or biofilm modes of growth. Populations that evolved in environments with shared selection pressures (either level of carbon availability or mode of growth) were more genetically similar to each other than populations from environments that shared neither characteristic. However, not all shared selection pressures led to parallel evolution. Genetic parallelism between low-carbon biofilm and low-carbon planktonic populations was very low despite shared selection for growth under low-carbon conditions, suggesting that evolution in low-carbon environments may generate stronger trade-offs between biofilm and planktonic modes of growth. For all environments, a population's fitness in a particular environment was positively correlated with the genetic similarity between that population and the populations that evolved in that particular environment. Although genetic similarity was low between low-carbon environments, overall, evolution in similar environments led to higher levels of genetic parallelism and that genetic parallelism, in turn, was correlated with fitness in a particular environment.

Use of genetic, climatic, and microbiological data to inform reintroduction of a regionally extinct butterfly

Species reintroductions are increasingly used as means of mitigating biodiversity loss. Besides habitat quality at the site targeted for reintroduction, the choice of source population can be critical for success. The butterfly Melanargia russiae (Esper´s marbled white) was extirpated from Hungary over 100 years ago, and a reintroduction program has recently been approved. We used museum specimens of this butterfly, mitochondrial DNA data (mtDNA), endosymbiont screening, and climatic-similarity analyses to determine which extant populations should be used for its reintroduction. The species displayed 2 main mtDNA lineages across its range: 1 restricted to Iberia and southern France (Iberian lineage) and another found throughout the rest of its range (Eurasian lineage). These 2 lineages possessed highly divergent wsp alleles of the bacterial endosymbiont Wolbachia. The century-old Hungarian specimens represented an endemic haplotype belonging to the Eurasian lineage, differing by one mutation from the Balkan and eastern European populations. The Hungarian populations of M. russiae occurred in areas with a colder and drier climate relative to most sites with extant known populations. Our results suggest the populations used for reintroduction to Hungary should belong to the Eurasian lineage, preferably from eastern Ukraine (genetically close and living in areas with the highest climatic similarity). Materials stored in museum collections can provide unique opportunities to document historical genetic diversity and help direct conservation.

Guidelines for planning genomic assessment and monitoring of locally adaptive variation to inform species conservation

Identifying and monitoring locally adaptive genetic variation can have direct utility for conserving species at risk, especially when management may include actions such as translocations for restoration, genetic rescue, or assisted gene flow. However, genomic studies of local adaptation require careful planning to be successful, and in some cases may not be a worthwhile use of resources. Here, we offer an adaptive management framework to help conservation biologists and managers decide when genomics is likely to be effective in detecting local adaptation, and how to plan assessment and monitoring of adaptive variation to address conservation objectives. Studies of adaptive variation using genomic tools will inform conservation actions in many cases, including applications such as assisted gene flow and identifying conservation units. In others, assessing genetic diversity, inbreeding, and demographics using selectively neutral genetic markers may be most useful. And in some cases, local adaptation may be assessed more efficiently using alternative approaches such as common garden experiments. Here, we identify key considerations of genomics studies of locally adaptive variation, provide a road map for successful collaborations with genomics experts including key issues for study design and data analysis, and offer guidelines for interpreting and using results from genomic assessments to inform monitoring programs and conservation actions.

Effect of migration and environmental heterogeneity on the maintenance of quantitative genetic variation: a simulation study

The paradox of high genetic variation observed in traits under stabilizing selection is a long-standing problem in evolutionary theory, as mutation rates appear too low to explain observed levels of standing genetic variation under classic models of mutation-selection balance. Spatially or temporally heterogeneous environments can maintain more standing genetic variation within populations than homogeneous environments, but it is unclear whether such conditions can resolve the above discrepancy between theory and observation. Here, we use individual-based simulations to explore the effect of various types of environmental heterogeneity on the maintenance of genetic variation (V_A ) for a quantitative trait under stabilizing selection. We find that V_A is maximized at intermediate migration rates in spatially heterogeneous environments and that the observed patterns are robust to changes in population size. Spatial environmental heterogeneity increased variation by as much as 10-fold over mutation-selection balance alone, whereas pure temporal environmental heterogeneity increased variance by only 45% at max. Our results show that some combinations of spatial heterogeneity and migration can maintain considerably more variation than mutation-selection balance, potentially reconciling the discrepancy between theoretical predictions and empirical observations. However, given the narrow regions of parameter space required for this effect, this is unlikely to provide a general explanation for the maintenance of variation. Nonetheless, our results suggest that habitat fragmentation may affect the maintenance of V_A and thereby reduce the adaptive capacity of populations.

Identification of a contact zone and hybridization for two subspecies of the American pika (Ochotona princeps) within a single protected area

Genetic variation is the basis upon which natural selection acts to yield evolutionary change. In a rapidly changing environment, increasing genetic variation should increase evolutionary potential, particularly for small, isolated populations. However, the introduction of new alleles, either through natural or human-mediated processes, may have unpredictable consequences such as outbreeding depression. In this study, we identified a contact zone and limited gene flow between historically separated genetic lineages of American pikas (Ochotona princeps), representing the northern and southern Rocky Mountain subspecies, within Rocky Mountain National Park. The limited spatial extent of gene flow observed may be the result of geographic barriers to dispersal, selection against hybrid individuals, or both. Our fine-scale population genetic analysis suggests gene flow is limited but not completely obstructed by extreme topography such as glacial valleys, as well as streams including the Colorado River. The discovery of two subspecies within this single protected area has implications for monitoring and management, particularly in the light of recent analyses suggesting that the pikas in this park are vulnerable to fragmentation and local extinction under future projected climates. Future research should focus on the fitness consequences of introgression among distinct genetic lineages in this location and elsewhere, as well as within the context of genetic rescue as a conservation and management strategy for a climate sensitive species.

Genetic differentiation, local adaptation and phenotypic plasticity in fragmented populations of a rare forest herb

Background

Due to habitat loss and fragmentation, numerous forest species are subject to severe population decline. Investigating variation in genetic diversity, phenotypic plasticity and local adaptation should be a prerequisite for implementing conservation actions. This study aimed to explore these aspects in ten fragmented populations of Physospermum cornubiense in view of translocation measures across its Italian range.

Methods

For each population we collected environmental data on landscape (habitat size, quality and fragmentation) and local conditions (slope, presence of alien species, incidence of the herbivorous insect Metcalfa pruinosa and soil parameters). We measured vegetative and reproductive traits in the field and analysed the genetic population structure using ISSR markers (STRUCTURE and AMOVA). We then estimated the neutral (F_ST) and quantitative (P_ST) genetic differentiation of populations.

Results

The populations exhibited moderate phenotypic variation. Population size (range: 16–655 individuals), number of flowering adults (range: 3–420 individuals) and inflorescence size (range: 5.0–8.4 cm) were positively related to Mg soil content. Populations’ gene diversity was moderate (Nei-H = 0.071–0.1316); STRUCTURE analysis identified five different clusters and three main geographic groups: upper, lower, and Apennine/Western Po plain. Fragmentation did not have an influence on the local adaptation of populations, which for all measured traits showed P_ST < F_ST, indicating convergent selection.

Discussion

The variation of phenotypic traits across sites was attributed to plastic response rather than local adaptation. Plant translocation from suitable source populations to endangered ones should particularly take into account provenance according to identified genetic clusters and specific soil factors.

Limited pollen dispersal, small genetic neighborhoods, and biparental inbreeding in Vallisneria americana

PREMISE OF THE STUDY

Pollen dispersal is a key process that influences ecological and evolutionary dynamics of plant populations by facilitating sexual reproduction and gene flow. Habitat loss and fragmentation have the potential to reduce pollen dispersal within and among habitat patches. We assessed aquatic pollen dispersal and mating system characteristics in Vallisneria americana-a water-pollinated plant with a distribution that has been reduced from historic levels.

METHODS

We examined pollen neighborhood size, biparental inbreeding, and pollen dispersal, based on seed paternity using the indirect paternity method KinDist, from samples of 18-39 mothers and 14-20 progeny per mother from three sites across 2 years.

KEY RESULTS

On average, fruits contained seeds sired by seven fathers. We found significant biparental inbreeding and limited pollen dispersal distances (0.8-4.34 m). However, in a number of cases, correlated paternity did not decline with distance, and dispersal could not be reliably estimated.

CONCLUSIONS

Frequent pollen dispersal is not expected among patches, and even within patches, gene flow via pollen will be limited. Limited pollen dispersal establishes genetic neighborhoods, which, unless overcome by seed and propagule dispersal, will lead to genetic differentiation even in a continuous population. Unless loss and fragmentation drive populations to extreme sex bias, local pollen dispersal is likely to be unaffected by habitat loss and fragmentation per se because the spatial scale of patch isolation already exceeds pollen dispersal distances. Therefore, managing specifically for pollen connectivity is only relevant over very short distances.

Conservation and the 4 Rs, which are rescue, rehabilitation, release, and research

Vertebrate animals can be injured or threatened with injury through human activities, thus warranting their "rescue." Details of wildlife rescue, rehabilitation, release, and associated research (our 4 Rs) are often recorded in large databases, resulting in a wealth of available information. This information has huge research potential and can contribute to understanding of animal biology, anthropogenic impacts on wildlife, and species conservation. However, such databases have been little used, few studies have evaluated factors influencing success of rehabilitation and/or release, recommended actions to conserve threatened species have rarely arisen, and direct benefits for species conservation are yet to be demonstrated. We therefore recommend that additional research be based on data from rescue, rehabilitation, and release of animals that is broader in scope than previous research and would have community support.

Phylogeography of southern brown and golden bandicoots: implications for the taxonomy and distribution of endangered subspecies and species

Southern brown (Isoodon obesulus) and golden (Isoodon auratus) bandicoots are iconic Australian marsupials that have experienced dramatic declines since European settlement. Conservation management programs seek to protect the remaining populations; however, these programs are impeded by major taxonomic uncertainties. We investigated the history of population connectivity to inform subspecies and species boundaries through a broad-scale phylogeographic and population genetic analysis of Isoodon taxa. Our analyses reveal a major east–west phylogeographic split within I. obesulus/I. auratus, supported by both mtDNA and nuclear gene analyses, which is not coincident with the current species or subspecies taxonomy. In the eastern lineage, all Tasmanian samples formed a distinct monophyletic haplotype group to the exclusion of all mainland samples, indicative of long-term isolation of this population from mainland Australia and providing support for retention of the subspecific status of the Tasmanian population (I. o. affinis). Analyses further suggest that I. o. obesulus is limited to south-eastern mainland Australia, representing a significant reduction in known range. However, the analyses provide no clear consensus on the taxonomic status of bandicoot populations within the western lineage, with further analyses required, ideally incorporating data from historical museum specimens to fill distributional gaps.

Plant conservation in Australia: Current directions and future challenges

Australia is a large, old and flat island continent that became isolated following the breakup of the Gondwanan super continent. After more than 40-50 M years of independent evolution, approx. 600,000-700,000 species now call Australia home. More than 21,000 of these species are plants, with at least 84% of these being endemic. Plant taxa are protected, conserved and managed under a range of legislation at the State- and Territory-level as well as Federally for matters of national significance. This can create issues of misalignment among threatened species lists but generally there is co-operation among conservation agencies to reduce misalignments and to manage species irrespective of jurisdictional borders. Despite significant investment in programs designed to assist the recovery of Australian biodiversity, threatened plants in particular appear to be continuing to decline. This can be attributed to a range of factors including major threatening processes associated with habitat loss and invasive species, lack of public awareness of the cultural and socio-economic value of plant conservation, and our relatively poor understanding of basic species taxonomy and biology, especially for those species that have specific interactions with pollinators, symbionts and herbivores. A recent shift in Federally-based conservation programs has been to identify 30 key plant species for recovery through the setting of measurable targets, improving the support provided to recovery teams and encouraging industry, business and philanthropy to support conservation actions.