Sink Populations Research Articles

Gene pool transmission of multidrug resistance among Campylobacter from livestock, sewage and human disease.

SummaryThe use of antimicrobials in human and veterinary medicine has coincided with a rise in antimicrobial resistance (AMR) in the food‐borne pathogens Campylobacter jejuni and Campylobacter coli. Faecal contamination from the main reservoir hosts (livestock, especially poultry) is the principal route of human infection but little is known about the spread of AMR among source and sink populations. In particular, questions remain about how Campylobacter resistomes interact between species and hosts, and the potential role of sewage as a conduit for the spread of AMR. Here, we investigate the genomic variation associated with AMR in 168 C. jejuni and 92 C. coli strains isolated from humans, livestock and urban effluents in Spain. AMR was tested in vitro and isolate genomes were sequenced and screened for putative AMR genes and alleles. Genes associated with resistance to multiple drug classes were observed in both species and were commonly present in multidrug‐resistant genomic islands (GIs), often located on plasmids or mobile elements. In many cases, these loci had alleles that were shared among C. jejuni and C. coli consistent with horizontal transfer. Our results suggest that specific antibiotic resistance genes have spread among Campylobacter isolated from humans, animals and the environment.

Quantifying the contribution of immigration to population dynamics: a review of methods, evidence and perspectives in birds and mammals.

The demography of a population is often reduced to the apparent (or local) survival of individuals and their realised fecundity within a study area defined according to logistical constraints rather than landscape features. Such demographics are then used to infer whether a local population contributes positively to population dynamics across a wider landscape context. Such a simplistic approach ignores a fundamental process underpinning population dynamics: dispersal. Indeed, it has long been accepted that immigration contributed by dispersers that emigrated from neighbouring populations may strongly influence the net growth of a local population. To date however, we lack a clear picture of how widely immigration rate varies both among and within populations, in relation to extrinsic and intrinsic ecological conditions, even for the best-studied avian and mammalian populations. This empirical knowledge gap precludes the emergence of a sound conceptual framework that ought to inform conservation and population ecology. This review, conducted on both birds and mammals, has thus three complementary objectives. First, we describe and evaluate the relative merits of methods used to quantify immigration and how they relate to widely applicable metrics. We identify two simple and unifying metrics to measure immigration: the immigration rate it defined as the ratio of the number of immigrants present in the population at time t+1 and the total breeding population in year t, and πt , the proportion of immigrants among new recruits (i.e. new breeders). Two recently developed methods are likely to provide the most valuable data on immigration in the near future: individual parentage (rather than population) assignments based on genetic sampling, and spatially explicit integrated population models combining multiple sources of demographic data (survival, fecundity and population counts). Second, we report on a systematic literature review of studies providing a quantitative measure of immigration. Although the diversity of methods employed precludes detailed analyses, it appears that the number of immigrants exceeds locally born individuals in recruitment for most avian populations (median πt =0.57, N=45 estimates from 37 studies), a figure twofold higher than estimated for mammalian populations (median πt =0.26, N=33 estimates from 11 studies). Third, recent quantitative studies reveal that immigration can be the main driver of temporal variation in population growth rates, across a wide array of demographic and spatial contexts. To what extent immigration acts as a regulatory process has however been considered only rarely to date and deserves more attention. Overall, it is likely that most populations benefit from immigrants without necessarily being sink populations. Furthermore, we suggest that quantitative estimates of immigration should be core to future demographic studies and plead for more empirical evidence about the ways in which immigration interacts with local demographic processes to shape population dynamics. Finally, we discuss how to tackle spatial population dynamics by exploring, beyond the classical source-sink framework, the extent to which populations exchange individuals according to spatial scale and type of population distribution throughout the landscape.

Advances in population ecology and species interactions in mammals

AbstractThe study of mammals has promoted the development and testing of many ideas in contemporary ecology. Here we address recent developments in foraging and habitat selection, source–sink dynamics, competition (both within and between species), population cycles, predation (including apparent competition), mutualism, and biological invasions. Because mammals are appealing to the public, ecological insight gleaned from the study of mammals has disproportionate potential in educating the public about ecological principles and their application to wise management. Mammals have been central to many computational and statistical developments in recent years, including refinements to traditional approaches and metrics (e.g., capture-recapture) as well as advancements of novel and developing fields (e.g., spatial capture-recapture, occupancy modeling, integrated population models). The study of mammals also poses challenges in terms of fully characterizing dynamics in natural conditions. Ongoing climate change threatens to affect global ecosystems, and mammals provide visible and charismatic subjects for research on local and regional effects of such change as well as predictive modeling of the long-term effects on ecosystem function and stability. Although much remains to be done, the population ecology of mammals continues to be a vibrant and rapidly developing field. We anticipate that the next quarter century will prove as exciting and productive for the study of mammals as has the recent one.

Potential Uses of Genetic Studies for MPA Design

In recent years, coral reef degradation has been increasing. Management and conservation efforts have tended to focus only on the physical condition of the coral reefs with less attention to biological and oceanographic aspects, in particular genetics and hydrodynamics. Genetic data can illustrate the connectivity between and within populations of an organism, making it is possible to determine source and sink populations or sites. Studies of physical water movements can also illustrate the likely patterns of movement or predict the mobility of coral planulae. Both of these approaches can help to strengthen Marine Protected Area (MPA) design, especially at the formation stage, in particular MPAs focused on coral reef ecosystems. Together, these two approaches can provide data on biological networks in a region and help delineate stocks. The implications of such studies can help to identify conservation priorities and improve the effectiveness of management processes in Indonesia, and can certainly enable the refinement of general approaches to help produce management plans tailored to local and regional conditions and processes. This brief review aims to review the constraints that occur in the management process, including barriers to and potential benefits of integrating molecular and hydrodynamic data into the management and conservation process, as illustrated through a critical review of MPA implementation in the waters around Sulawesi Island.

Elusive enemies: Consumptive and ovipositional effects on mosquitoes by predatory midge larvae are enhanced in dyed environments

Mosquito-borne disease incidences continue to proliferate and cause enormous mortality and debilitation rates. Predatory natural enemies can be effective in population management strategies targeting medically-important mosquito species. However, context-dependencies and target organism behavioural responses can impede or facilitate biological control agents. Black pond dye has been shown to be a strong mosquito oviposition attractant, and could potentially be used alongside predatory agents to create mosquito population sink effects. Here, we thus examine the predatory impact of larvae of the non-biting chaoborid midge Chaoborus flavicans towards larvae of the West Nile virus vector mosquito complex Culex pipiens in the presence and absence of black pond dye. We then examine the ovipositional responses of C. pipiens to predation risk and dye in laboratory-, semi-field- and field-based trials. Larval C. flavicans exhibited potentially population destabilising type II functional responses towards mosquito larvae irrespective of the presence of pond dye. Neither consumption rates nor functional response parameters (attack rates, handling times) were significantly influenced by the presence of dye, indicating a use of hydromechanics to detect mosquito prey by chaoborids. Wild-caught adult C. pipiens did not avoid predatory chaoborids when ovipositing, however they were significantly more attracted to oviposit in dye-treated water regardless of the presence of predators. We thus demonstrate high predatory impact towards mosquito larvae by non-biting chaoborid midges during their predaceous aquatic larval stages, and proliferations of such predators may assist or augment control efforts for mosquitoes. Our results suggest a lack of influence of predatory dipterans on oviposition selectivity by C. pipiens mosquitoes, and that pond dye may enhance the efficacy of select predatory biological control agents through the creation of population sinks, characterised by high rates of oviposition and subsequent predation.

Cryptic temporal changes in stock composition explain the decline of a flounder (Platichthys spp.) assemblage.

Unobserved diversity, such as undetected genetic structure or the presence of cryptic species, is of concern for the conservation and management of global biodiversity in the face of threatening anthropogenic processes. For instance, unobserved diversity can lead to overestimation of maximum sustainable yields and therefore to overharvesting of the more vulnerable stock components within unrecognized mixed‐stock fisheries. We used DNA from archival (otolith) samples to reconstruct the temporal (1976–2011) genetic makeup of two mixed‐stock flounder fisheries in the Åland Sea (AS) and the Gulf of Finland (GoF). Both fisheries have hitherto been managed as a single stock of European flounders (Platichthys flesus), but were recently revealed to target two closely related species: the pelagic‐spawning P. flesus and the newly described, demersal‐spawning P. solemdali. While the AS and GoF fisheries were assumed to consist exclusively of P. solemdali, P. flesus dominated the GoF flounder assemblage (87% of total) in 1983, had disappeared (0%) by 1993, and remained in low proportions (10%–11%) thereafter. In the AS, P. solemdali dominated throughout the sampling period (>70%), and P. flesus remained in very low proportions after 1983. The disappearance of P. flesus from the GoF coincides in time with a dramatic (~60%) decline in commercial landings and worsening environmental conditions in P. flesus’ northernmost spawning ground, the Eastern Gotland Basin, in the preceding 4–6 years. These results are compatible with the hypothesis that P. flesus in the GoF is a sink population relying on larval subsidies from southern spawning grounds and the cause of their disappearance is a cessation of larval supply. Our results highlight the importance of uncovering unobserved genetic diversity and studying spatiotemporal changes in the relative contribution of different stock components, as well as the underlying environmental causes, to manage marine resources in the age of rapid anthropogenic change.

Demography and genetics suggest reversal of dolphin source‐sink dynamics, with implications for conservation

AbstractThe forecast for the viability of populations depends upon metapopulation dynamics: the combination of reproduction and mortality within populations, as well as dispersal between populations. This study focuses on an Indo‐Pacific bottlenose dolphin (Tursiops aduncus) population in coastal waters near Bunbury, Western Australia. Demographic modeling of this population suggested that recent reproductive output was not sufficient to offset mortality. Migrants from adjacent populations might make up this deficit, so that Bunbury would act as a “sink,” or net recipient population. We investigated historical dispersal in and out of Bunbury, using microsatellites and mitochondrial DNA of 193 dolphins across five study locations along the southwestern Australian coastline. Our results indicated limited gene flow between Bunbury and adjacent populations. The data also revealed a net‐dispersal from Bunbury to neighboring populations, with microsatellites showing that more than twice as many individuals per generation dispersed out of Bunbury than into Bunbury. Therefore, in historic times, Bunbury appears to have acted as a source population, supporting nearby populations. In combination with the prior finding that Bunbury is currently not producing surplus offspring to support adjacent populations, this potential reversal of source‐sink dynamics may have serious conservation implications for Bunbury and other populations nearby.

Comparison between Anuran Call Only and Multiple Life-Stage Occupancy Designs in Missouri River Floodplain Wetlands following a Catastrophic Flood

Abstract Amphibian conservation studies often rely on auditory call surveys to determine distribution, abundance, and habitat associations of anuran species. Call surveys omit important life stages, however, and conservation recommendations from call surveys alone risk creating population sinks or ecological traps. To more effectively determine the effects of a catastrophic flood on an amphibian community, we surveyed tadpoles and metamorphs of six anuran species in the Missouri River floodplain in 2012 and 2013. Inference gleaned from these surveys was compared to inference from previous work with call surveys. For 8 of 10 species-years, extinction probabilities were >0 for tadpole and metamorph stages, indicating there may be habitat factors affecting tadpoles and metamorphs beyond those affecting calling adult males. In several cases we discovered habitat associations for tadpoles and metamorphs that were not present during call surveys. We had previously recommended shallow slopes for Blanchard's Cric...

Metapopulation dynamics of roseate terns: Sources, sinks and implications for conservation management decisions.

Habitat management to restore or create breeding sites may allow metapopulations to increase in size and reduce the risk of demographic stochasticity or disasters causing metapopulation extinction. However, if newly restored or created sites are of low quality, they may act as sinks that draw individuals away from better quality sites to the detriment of metapopulation size. Following intensive conservation effort, the metapopulation of roseate tern (Sterna dougallii) in NW Europe is recovering from a large crash in numbers, but most former colonies remain unoccupied and hence are potential targets for restoration. To inform conservation efforts, we studied the dynamics of this metapopulation with a multistate integrated population model to assess each of the three main colonies for important demographic contributors to population growth rate, source/sink status and possible density dependence. All three study colonies are managed for roseate terns (and other tern species) in similar ways, but the demographic processes vary considerably between colonies. The largest colony is a source involved in almost all dispersal, and its growth is determined by survival rates and productivity. Productivity and juvenile apparent survival at the largest colony appear to be density-dependent. Although the mechanisms are unclear, this may provide an increasing impetus for emigration of recruits to other colonies in future. The smallest of the three colonies is a sink, relying on immigration for its growth. Simulation models suggest the metapopulation would be c. 10% larger in the absence of dispersal to the sink colony. This work indicates that, due to variable site quality, aims to enhance both distribution and size of metapopulations may be mutually exclusive. In this case, before future attempts to encourage recolonisation of former sites, assessments of site suitability should be undertaken, focusing on food availability and isolation from predators to maximise the likelihood of attaining levels of productivity and survival that avoid creation of a sink population to the detriment of the overall metapopulation size.

Gene pool and connectivity patterns of Pinna nobilis in the Balearic Islands (Spain, Western Mediterranean Sea): Implications for its conservation through restocking

Abstract Pinna nobilis is an endemic bivalve of the Mediterranean Sea, and a vulnerable species registered as endangered and protected under the European Council Directive 92/43/EEC and Barcelona Convention. In early autumn 2016, a mass mortality event impacted P. nobilis populations in the south‐western Mediterranean Sea, including the Balearic Islands. At the time of this study, P. nobilis still maintained high population densities along the Balearic coasts (Western Mediterranean). This study evaluated the connectivity of P. nobilis post‐larvae and adults in seagrass habitats around the Balearic Islands and identified its source and sink populations. These objectives were reached through a multidisciplinary approach including population genetics (10 microsatellites) and hydrodynamic modelling. High genetic diversity was found and significant genetic differentiation (inferred by fixation index FST) was detected between post‐larvae samples, but not between adult populations. Significant genic and genotypic differentiation was recorded for adults and post‐larvae. This pattern was confirmed by correspondence analysis using allele frequencies. The genetic connectivity pattern was consistent with marine currents and dispersal models. This work not only improves knowledge of the P. nobilis gene pool in south‐west Mediterranean populations and their connectivity patterns, but is also crucial to help evaluate the possibility of recovery from source populations and the possibility of restocking programmes, as well as provide a solid base to establish effective marine reserve networks.

Increased spatial and temporal autocorrelation of temperature under climate change

Understanding spatiotemporal variation in environmental conditions is important to determine how climate change will impact ecological communities. The spatial and temporal autocorrelation of temperature can have strong impacts on community structure and persistence by increasing the duration and the magnitude of unfavorable conditions in sink populations and disrupting spatial rescue effects by synchronizing spatially segregated populations. Although increases in spatial and temporal autocorrelation of temperature have been documented in historical data, little is known about how climate change will impact these trends. We examined daily air temperature data from 21 General Circulation Models under the business-as-usual carbon emission scenario to quantify patterns of spatial and temporal autocorrelation between 1871 and 2099. Although both spatial and temporal autocorrelation increased over time, there was significant regional variation in the temporal autocorrelation trends. Additionally, we found a consistent breakpoint in the relationship between spatial autocorrelation and time around the year 2030, indicating an acceleration in the rate of increase of the spatial autocorrelation over the second half of the 21st century. Overall, our results suggest that ecological populations might experience elevated extinction risk under climate change because increased spatial and temporal autocorrelation of temperature is expected to erode both spatial and temporal refugia.

Ecological and Evolutionary Classification of Subterranean Organisms

Evolutionary processes, including natural selection, neutral mutation, and habitat filtering, act upon morphology and other aspects of their biology, as well as species composition itself, to produce the observed patterns or community structure and morphology. The context for these evolutionary processes (the ecological theater in G.E. Hutchinson’s phrase) are the subterranean habitats. We have a relatively rich vocabulary to describe habitats (e.g., MSS, epikarst, hypotelminorheic) and to describe the closeness of association of a particular species or population with these habitats (e.g. trogloxene, troglophile, and troglobiont). Trajano provides a bridging principle between the ecological theater and the evolutionary play with the concept of source and sink populations. What has been given much less attention is the morphological side, coined by Christiansen, that is the results of the evolutionary play. The word we have available is “troglomorphy”, which has been taken to mean loss of eyes and pigment, loss of eyes and pigment as well as increases in extra-optic sensory structures, any convergent change in any subterranean population. loss of eyes and pigment, loss of eyes and pigment as well as increases in extra-optic sensory structures, any convergent change in any subterranean population. Only regressive changes are included in the first meaning; both regressive and progressive changes are included in the second; and the third includes autamorphy as well as homoplasy. Typically, it is used for the suite of characters involved, rather than an individual character. We suggest that the term “troglomorphy” be restricted to convergent changes (in the sense of [2] above) in subterranean habitats, and that the phrase “cave-dependent”, also used by Christiansen, be used when considering only caves, and perhaps be joined by phrases such as “MSS-dependent”. Additionally, the phrases ‘cave-dependent”, “MSS-dependent”, etc. be used for individual characters.

Population connectivity among shallow and mesophotic Montastraea cavernosa corals in the Gulf of Mexico identifies potential for refugia

Successful management of spatially isolated coral reefs is contingent on an understanding of ecological connections across populations. To investigate genetic connectivity of the depth-generalist coral species Montastraea cavernosa, populations from both shallow (15–30 m) and mesophotic coral ecosystems (30–70 m) in the Gulf of Mexico (GOM) were analyzed with microsatellite genotyping. A series of upstream and downstream sites were chosen in marine protected areas including Carrie Bow Cay, Belize; Flower Garden Banks and nearby mesophotic bank habitats; Pulley Ridge; and Dry Tortugas. Patterns of genetic diversity within the northwest GOM supported relatively open coral populations with high levels of gene flow between shallow and mesophotic depth zones, consistent with strong oceanographic patterns and hypothesized availability of coral reef habitats in the GOM. Conversely, genetic differentiation within Belize and the southeast GOM indicate relative isolation of shallow and mesophotic M. cavernosa populations in these regions. Structure analysis showed dominant genetic clusters within each region that did not correlate strongly with depth zones, and identified a cluster of unknown origin contributing to high differentiation at Pulley Ridge. Migration modeling predicted historical region-wide panmixia for most regions, with Pulley Ridge appearing to be a potential sink population. The GOM appears to demonstrate stronger evidence of vertical connectivity compared to elsewhere in the Tropical Western Atlantic, which may be the result of oceanographic variability and/or lack of local selection at depth. These findings are consistent with previous studies identifying genetic connectivity of broadcast-spawning corals across broad spatial scales and highlight the potential importance of mesophotic habitats in the GOM as larval sources to geographically distant populations.

Impacts of marine and freshwater aquaculture on wildlife: a global meta‐analysis

AbstractThe global expansion of aquaculture has raised concerns about its environmental impacts, including effects on wildlife. Aquaculture farms are thought to repel some species and function as either attractive population sinks (‘ecological traps’) or population sources for others. We conducted a systematic review and meta‐analysis of empirical studies documenting interactions between aquaculture operations and vertebrate wildlife. Farms were associated with elevated local abundance and diversity of wildlife, although this overall effect was strongly driven by aggregations of wild fish at sea cages and shellfish farms (abundance: 72×; species richness: 2.0×). Birds were also more diverse at farms (1.1×), but other taxa showed variable and comparatively small effects. Larger effects were reported when researchers selected featureless or unstructured habitats as reference sites. Evidence for aggregation ‘hotspots’ is clear in some systems, but we cannot determine whether farms act as ecological traps for most taxa, as few studies assess either habitat preference or fitness in wildlife. Fish collected near farms were larger and heavier with no change in body condition, but also faced higher risk of disease and parasitism. Birds and mammals were frequently reported preying on stock, but little data exist on the outcomes of such interactions for birds and mammals – farms are likely to function as ecological traps for many species. We recommend researchers measure survival and reproduction in farm‐associated wildlife to make direct, causal links between aquaculture and its effects on wildlife populations.

Predicting the fate of the most endangered marine invertebrate of the Mediterranean: The power of long‐term monitoring in conservation biology

Abstract Global climate change and other human‐induced alterations of the environment are causing a significant loss in biodiversity. Among the many species affected is the giant limpet Patella ferruginea, considered as the most endangered marine invertebrate within the Western Mediterranean basin. The results of a 10‐year monitoring programme in an updated population viability analysis (PVA) model are provided, which indicate the unlikeliness of the population in Ceuta facing extinction within the next 50 years. Evidence is provided for the possible role of this population as a source population for other sink populations in the Alboran Sea. Large interannual variations in recruitment have been recorded, and the general linear model (GLM) indicates the influence of chlorophyll and temperature on recruitment rates. These results inform conservation strategies for this flagship species.

Impact of supplementation on deleterious mutation distribution in an exploited salmonid.

Deleterious mutations have important implications for the evolutionary trajectories of populations. While several studies recently investigated the dynamics of deleterious mutations in wild populations, no study has yet explored the fate of deleterious mutations in a context of populations managed by supplementation. Here, based on a dataset of nine wild and 15 supplemented Lake Trout populations genotyped at 4,982 single nucleotide polymorphisms (SNP)s by means of genotype by sequencing (GBS), we explored the effect of supplementation on the frequency of putatively deleterious variants. Three main findings are consequential for the management of fish populations. First, an increase in neutral genetic diversity in stocked populations compared with unstocked ones was observed. Second, putatively deleterious mutations were more likely to be found in unstocked than in stocked populations, suggesting a lower efficiency to purge deleterious mutations in unstocked lakes. Third, a population currently used as a major source for supplementation is characterized by several fixed putatively deleterious alleles. Therefore, other source populations with lower abundance of putatively deleterious mutations should be favored as sources of supplementation. We discuss management implications of our results, especially pertaining to the joint identification of neutral and deleterious mutations that could help refining the choice of source and sink populations for supplementation in order to maximize their evolutionary potential and to limit their mutation load.

Source‐sink dynamics of bumblebees in rapidly changing landscapes

Abstract Bumblebees inhabit spatially heterogeneous landscapes that are likely characterized by population sources and sinks. To date, most studies of bumblebee habitat requirements have examined static relationships between worker abundance and habitat characteristics. However, if habitat types are linked by dispersal, source‐sink dynamics could alter overall population sensitivity to habitat loss, changing conclusions from static approaches. Here, we used empirically derived spatial matrix models to study source‐sink population dynamics of bumblebees in heterogeneous environments. We used these models to assess population sensitivity to habitat loss and to examine the population dynamics that could occur under rapid habitat change. Loss of natural habitat reduced long‐term population growth rates, and more natural habitat was required to sustain bumblebee species with long‐distance dispersal than species with short‐distance dispersal. The long‐term relative density of colonies in each habitat type depended on landscape structure and bumblebee dispersal ability. Under most conditions, high‐quality habitat contained higher densities of colonies than low‐quality habitats. However, low‐quality habitat could contain higher densities than high‐quality habitats if populations were in long‐term decline. Rapid loss or restoration of natural habitat produced transient population dynamics that differed from long‐term dynamics. After large landscape perturbations that affected population structure, transient dynamics persisted for 4–8 years and were longest for species with short dispersal in highly aggregated landscapes. While transient dynamics were short in duration, they caused large effects on long‐term population density. Synthesis and applications. When habitats are linked by dispersal or populations have recently experienced perturbations, patterns of abundance on the landscape may not reflect variation in habitat quality. Spatially structured matrix population models are practical tools than can be used to account for nonequilibrium and source‐sink dynamics. For bumblebees, population sensitivity to habitat loss and the duration of transient dynamics depend on dispersal ability and landscape configuration. Demographic approaches such as ours can help to disentangle population patterns from processes and will therefore be valuable for guiding conservation and management.

River otters (Lontra canadensis) “trapped” in a coastal environment contaminated with persistent organic pollutants: Demographic and physiological consequences

Productive coastal and estuarine habitats can be degraded by contaminants including persistent organic pollutants (POPs) such as PCBs, dioxins, and organochlorine insecticides to the extent of official designation as contaminated sites. Top-predatory wildlife may continue to use such sites as the habitat often appears suitable, and thus bioaccumulate POPs and other contaminants with potential consequences on their health and fitness. Victoria and Esquimalt harbours are located on southern Vancouver Island, British Columbia (BC) and are federally designated contaminated sites due mainly to past heavy industrial activities, such as from shipyards and sawmills. We collected scat samples from river otters (Lontra canadensis) throughout an annual cycle, and combined chemical analysis with DNA genotyping to examine whether the harbour areas constituted a contaminant-induced ecological trap for otters. We confirmed spatial habitat use by radio telemetry of a subsample of otters. Fifteen percent of otter scat contained PCB concentrations exceeding levels considered to have adverse effects on the reproduction of mink (Neovison vison), and there were significant positive correlations between concentrations of PCBs and of thyroid (T3) and sex (progesterone) hormones in fecal samples. Radio telemetry data revealed that otters did not show directional movement away from the harbours, indicating their inability to recognize the contaminated site as a degraded habitat. However, analysis and modeling of the DNA genotyping data provided no evidence that the harbour otters formed a sink population and therefore were in an ecological trap. Despite the highly POP-contaminated habitat, river otters did not appear to be adversely impacted at the population level. Our study demonstrates the value of combining chemical and biological technologies with ecological theory to investigate practical conservation problems.

Genetic and oceanographic tools reveal high population connectivity and diversity in the endangered pen shell Pinna nobilis

For marine meta-populations with source-sink dynamics knowledge about genetic connectivity is important to conserve biodiversity and design marine protected areas (MPAs). We evaluate connectivity of a Mediterranean sessile species, Pinna nobilis. To address a large geographical scale, partial sequences of cytochrome oxidase I (COI, 590 bp) were used to evaluate phylogeographical patterns in the Western Mediterranean, and in the whole basin using overlapping sequences from the literature (243 bp). Additionally, we combined (1) larval trajectories based on oceanographic currents and early life-history traits and (2) 10 highly polymorphic microsatellite loci collected in the Western Mediterranean. COI results provided evidence for high diversity and low inter-population differentiation. Microsatellite genotypes showed increasing genetic differentiation with oceanographic transport time (isolation by oceanographic distance (IBD) set by marine currents). Genetic differentiation was detected between Banyuls and Murcia and between Murcia and Mallorca. However, no genetic break was detected between the Balearic populations and the mainland. Migration rates together with numerical Lagrangian simulations showed that (i) the Ebro Delta is a larval source for the Balearic populations (ii) Alicante is a sink population, accumulating allelic diversity from nearby populations. The inferred connectivity can be applied in the development of MPA networks in the Western Mediterranean.

A framework for estimating the determinants of spatial and temporal variation in vital rates and inferring the occurrence of unobserved extreme events.

We develop a general framework that combines long-term tag–recapture data and powerful statistical and modelling techniques to investigate how population, environmental and climate factors determine variation in vital rates and population dynamics in an animal species, using as a case study the population of brown trout living in Upper Volaja (Western Slovenia). This population has been monitored since 2004. Upper Volaja is a sink, receiving individuals from a source population living above a waterfall. We estimate the numerical contribution of the source population on the sink population and test the effects of temperature, population density and extreme events on variation in vital rates among 2647 individually tagged brown trout. We found that individuals dispersing downstream from the source population help maintain high population densities in the sink population despite poor recruitment. The best model of survival for individuals older than juveniles includes additive effects of birth cohort and sampling occasion. Fast growth of older cohorts and higher population densities in 2004–2005 suggest very low population densities in the late 1990s, which we hypothesize were caused by a flash flood that strongly reduced population size and created the habitat conditions for faster individual growth and transient higher population densities after the extreme event.