Patterns Of Genetic Connectivity Research Articles

Rare, long-distance dispersal underpins genetic connectivity in the pink sea fan, Eunicella verrucosa.

Characterizing patterns of genetic connectivity in marine species is of critical importance given the anthropogenic pressures placed on the marine environment. For sessile species, population connectivity can be shaped by many processes, such as pelagic larval duration, oceanographic boundaries and currents. This study combines restriction-site associated DNA sequencing (RADseq) and passive particle dispersal modelling to delineate patterns of population connectivity in the pink sea fan, Eunicella verrucosa, a temperate octocoral. Individuals were sampled from 20 sites covering most of the species' northeast Atlantic range, and a site in the northwest Mediterranean Sea to inform on connectivity across the Atlantic-Mediterranean transition. Using 7510 neutral SNPs, a geographic cline of genetic clusters was detected, partitioning into Ireland, Britain, France, Spain (Atlantic), and Portugal and Spain (Mediterranean). Evidence of significant inbreeding was detected at all sites, a finding not detected in a previous study of this species based on microsatellite loci. Genetic connectivity was characterized by an isolation by distance pattern (IBD) (r 2 = 0.78, p < 0.001), which persisted across the Mediterranean-Atlantic boundary. In contrast, exploration of ancestral population assignment using the program ADMIXTURE indicated genetic partitioning across the Bay of Biscay, which we suggest represents a natural break in the species' range, possibly linked to a lack of suitable habitat. As the pelagic larval duration (PLD) is unknown, passive particle dispersal simulations were run for 14 and 21 days. For both modelled PLDs, inter-annual variations in particle trajectories suggested that in a long-lived, sessile species, range-wide IBD is driven by rare, longer dispersal events that act to maintain gene flow. These results suggest that oceanographic patterns may facilitate range-wide stepping-stone genetic connectivity in E. verrucosa and highlight that both oceanography and natural breaks in a species' range should be considered in the designation of ecologically coherent MPA networks.

Highly structured populations of deep-sea copepods associated with hydrothermal vents across the Southwest Pacific, despite contrasting life history traits

Hydrothermal vents are extreme environments, where abundant communities of copepods with contrasting life history traits co-exist along hydrothermal gradients. Here, we discuss how these traits may contribute to the observed differences in molecular diversity and population genetic structure. Samples were collected from vent locations across the globe including active ridges and back-arc basins and compared to existing deep-sea hydrothermal vent and shallow water data, covering a total of 22 vents and 3 non-vent sites. A total of 806 sequences of mtDNA from the Cox1 gene were used to reconstruct the phylogeny, haplotypic relationship and demography within vent endemic copepods (Dirivultidae, Stygiopontius spp.) and non-vent-endemic copepods (Ameiridae, Miraciidae and Laophontidae). A species complex within Stygiopontius lauensis was studied across five pacific back-arc basins at eight hydrothermal vent fields, with cryptic species being restricted to the basins they were sampled from. Copepod populations from the Lau, North Fiji and Woodlark basins are undergoing demographic expansion, possibly linked to an increase in hydrothermal activity in the last 10 kya. Highly structured populations of Amphiascus aff. varians 2 were also observed from the Lau to the Woodlark basins with populations also undergoing expansion. Less abundant harpacticoids exhibit little to no population structure and stable populations. This study suggests that similarities in genetic structure and demography may arise in vent-associated copepods despite having different life history traits. As structured meta-populations may be at risk of local extinction should major anthropogenic impacts, such as deep-sea mining, occur, we highlight the importance of incorporating a trait-based approach to investigate patterns of genetic connectivity and demography, particularly regarding area-based management tools and environmental management plans.

Does depth divide? Variable genetic connectivity patterns among shallow and mesophotic Montastraea cavernosa coral populations across the Gulf of Mexico and western Caribbean.

Despite general declines in coral reef ecosystems in the tropical western Atlantic, some reefs, including mesophotic reefs (30-150 m), are hypothesized to function as coral refugia due to their relative isolation from anthropogenic stressors. Understanding the connectivity dynamics among these putative refugia and more degraded reefs is critical to develop effective management strategies that promote coral metapopulation persistence and recovery. This study presents a geographically broad assessment of shallow (<30 m) and mesophotic (>30 m) connectivity dynamics of the depth-generalist coral species Montastraea cavernosa. Over 750 coral genets were collected across the Northwest and Southern Gulf of Mexico, Florida, Cuba, and Belize, and ~5000 SNP loci were generated to quantify high-resolution genetic structure and connectivity among these populations. Generally, shallow and mesophotic populations demonstrated higher connectivity to distant populations within the same depth zone than to adjacent populations across depth zones. However, exceptions to this pattern include the Northwest Gulf of Mexico and the Florida Keys which exhibited relatively high vertical genetic connectivity. Furthermore, estimates of recent gene flow emphasize that mesophotic M. cavernosa populations are not significant sources for their local shallow counterparts, except for the Northwest Gulf of Mexico populations. Location-based differences in vertical connectivity are likely a result of diverse oceanographic and environmental conditions that may drive variation in gene flow and depth-dependent selection. These results highlight the need to evaluate connectivity dynamics and refugia potential of mesophotic coral species on a population-by-population basis and to identify stepping-stone populations that warrant incorporation in future international management approaches.

Disparate population and holobiont structure of pocilloporid corals across the Red Sea gradient demonstrate species-specific evolutionary trajectories.

Global habitat degradation heightens the need to better understand patterns of genetic connectivity and diversity of marine biota across geographical ranges to guide conservation efforts. Corals across the Red Sea are subject to pronounced environmental differences, but studies so far suggest that animal populations are largely connected, excepting evidence for a genetic break between the northern-central and southern regions. Here, we investigated population structure and holobiont assemblage of two common pocilloporid corals, Pocillopora verrucosa and Stylophora pistillata, across the Red Sea. We found little evidence for population differentiation in P. verrucosa, except for the southernmost site. Conversely, S. pistillata exhibited a complex population structure with evidence for within-reef and regional genetic differentiation, in line with differences in their reproductive mode (P. verrucosa is a broadcast spawner and S. pistillata is a brooder). Analysis for genomic loci under positive selection identified 85 sites (18 of which were in coding sequences) that distinguished the southern P. verrucosa population from the remainder of the Red Sea population. By comparison, we found 128 loci (24 of which were residing in coding sequences) in S. pistillata with evidence for local adaptation at various sites. Functional annotation of the underlying proteins revealed putative roles in the response to stress, lipid metabolism, transport, cytoskeletal rearrangement, and ciliary function (among others). Microbial assemblages of both coral species showed pervasive association with microalgal symbionts from the genus Symbiodinium (former clade A) and bacteria from the genus Endozoicomonas that exhibited significant differences according to host genotype and environment. The disparity of population genetic and holobiont assemblage patterns even between closely related species (family Pocilloporidae) highlights the need for multispecies investigations to better understand the role of the environment in shaping evolutionary trajectories. It further emphasizes the importance of networks of reef reserves to achieve conservation of genetic variants critical to the future survival of coral ecosystems.

High levels of genetic diversity and population structure in the Mediterranean seagrass Posidonia oceanica at its easternmost distribution limit

Abstract High levels of genetic diversity and connectivity are crucial for the persistence of local populations, especially at the edge of species’ distribution ranges. Here, we assessed the potential and realized connectivity of populations of the Mediterranean seagrass Posidonia oceanica at its easternmost distribution using physical modelling and genetic analyses. Genetic assessments of diversity and gene flow among populations were carried out with 18 microsatellite loci, while oceanographic connectivity was assessed via Lagrangian dispersal simulations. Levels of genetic and clonal diversities were prevalent among shallow and deep sites without signs of reproductive isolation. Both approaches identified two main clusters corresponding to “Aegean” populations along the western Turkey coast and “Levantine” populations along the southern Turkey coast. Aegean populations were genetically homogeneous, connected by high levels of gene flow, whereas Levantine populations were genetically heterogeneous. Within-sea patterns of genetic connectivity did not fully overlap with those derived from physical modelling; the realized connectivity was greater than that predicted by ocean-current simulations, especially in the Aegean Sea. Lagrangian dispersion dynamics cannot necessarily explain genetic connectivity patterns among populations, which are shaped over longer temporal scales and can be affected by human activities and local environmental conditions.

Guiding marine protected area network design with comparative phylogeography and population genomics: An exemplary case from the Southern Ocean

AbstractAimNetworks of connected marine protected areas (MPAn) are recognized as the key area‐based management tool to preserve biodiversity, moderate exploitation of marine resources and increase ecological resilience to climate change. Although population genetic studies could greatly benefit connectivity assessments between MPAs, genetic data are rarely used in MPAn planning. Here, we aim to illustrate the use of a multispecies and multilocus approach to provide recommendations for MPAn design, highlighting the importance of the species selected and the analyses performed. Our study is focused on the Southern Ocean, an area of keen multinational interest given its scientific significance, economic importance and its unique, shared legal status.LocationSouth Georgia and South Sandwich Islands MPA (SGSSI MPA), the South Orkney Islands and the Western Antarctic Peninsula (WAP)—where an MPA was proposed in 2018 (Domain 1 MPA) but has not been approved by the Commission for the Conservation of the Antarctic Marine Living Resources (CCAMLR).MethodsOur datasets include 819 individuals from five different species with contrasting life‐history strategies: two nemerteans (Antarctonemertes valida and A. riesgoae), two annelids (Pterocirrus giribeti and Neanthes kerguelensis) and one sponge (Mycale [Oxymycale] acerata). To identify genetic connectivity patterns in our study area, spanning roughly 2500 km, we used the COI mitochondrial marker and genome‐wide ddRADseq‐derived SNPs.ResultsA consistent lack of connectivity between SGSSI MPA and the WAP was found for all studied species. Additionally, our data indicated a stepping‐stone role for the South Orkney Islands between these two genetically differentiated regions.Main conclusionsOur results reveal how the application of comparative phylogeography and population genomics can guide policymakers in their decision‐making process during MPAn design. We detected priority areas for conservation in Antarctica, including the South Orkney Islands and the WAP, providing strong evidence for the implementation of the Domain 1 MPA.

High gene flow in the silverlip pearl oyster Pinctada maxima between inshore and offshore sites near Eighty Mile Beach in Western Australia.

An understanding of stock recruitment dynamics in fisheries is fundamental to successful management. Pinctada maxima is a bivalve mollusc widely distributed throughout the Indo-Pacific and is the main species targeted for cultured pearl and pearl shell production in Australia. Pearl production in Australia relies heavily on wild-caught individuals, the majority of which come from the Eighty Mile Beach region near Broome in Western Australia. In this study, we used a genotyping by sequencing approach to explore fine-scale patterns of genetic connectivity among inshore shallow and offshore deep populations of P. maxima near Eighty Mile Beach. Our results revealed high-levels of gene flow among inshore and offshore sites and no differences in genetic diversity between depths. Global estimates of genetic differentiation were low (FST = 0.006) but significantly different from zero, and pairwise estimates of genetic differentiation among sites were significant in only 3% of comparisons. Moreover, Bayesian clustering detected no separation of inshore and offshore sample sites, and instead showed all samples to be admixed among sites, locations and depths. Despite an absence of any clear spatial clustering among sites, we identified a significant pattern of isolation by distance. In a dynamic environment like Eighty Mile Beach, genetic structure can change from year-to-year and successive dispersal and recruitment events over generations likely act to homogenize the population. Although we cannot rule out the null hypothesis of panmixia, our data indicate high levels of dispersal and connectivity among inshore and offshore fishing grounds.

Genomic assessment of an endemic Hawaiian surgeonfish, Acanthurus triostegus sandvicensis, reveals high levels of connectivity and fine-scale population structure

The Hawaiian Archipelago has served as a natural laboratory to assess genetic connectivity patterns across a broad spectrum of taxonomic and ecological diversity. Almost all these studies were based on a few targeted loci, but technologies now allow us to assess population structure with genomic coverage and greater resolution. Here, we provide a SNP-based analysis for an endemic surgeonfish, Acanthurus triostegus sandvicensis (manini) across the Hawaiian Archipelago and adjacent Johnston Atoll (N = 461). Based on 3649 SNPs, manini showed population structure in the main Hawaiian Islands, but genetic homogeneity across most of the northwestern extent of the archipelago (overall FST = 0.033, P < 0.001). Net migration occurred from Johnston Atoll into Hawai‘i, providing further support for Johnston Atoll being a pathway for dispersal (or colonization) into Hawai′i. These results highlight the higher efficacy of genomic sequencing to characterize fine-scale patterns of connectivity relative to a targeted loci approach and, moving forward, may invoke a reassessment of past connectivity studies in a genomics framework.

Updated connectivity assessment for the scalloped hammerhead (Sphyrna lewini) in Pacific and Indian Oceans using a multi-marker genetic approach

Patterns of genetic connectivity can be used to define the geographic boundaries of fishes and underpin management decisions. This study used a genetic multi-marker approach to investigate the population structure of scalloped hammerheads (Sphyrna lewini) in the Indo–Pacific. Samples from 541 S. lewini were collected from 12 locations across the Indo–Pacific. Samples were analysed using two regions of the mitochondrial genome, nine microsatellite loci and two sets of Single Nucleotide Polymorphisms (SNP). Our study has four key findings; (1) genetic structure of S. lewini across the Indo–Pacific is affected by oceanic basins and can be separated into four distinct regions. (2) Within the central Indo–Pacific, connectivity is facilitated along continental shelves and strong signals of Isolation-By-Distance (IBD) were observed. (3) Mitochondrial haplotypes previously thought only to exist in the Atlantic Ocean are observed in Indo–Pacific populations, suggesting the haplotype should be reconsidered as more widespread than initially thought. (4) Results from microsatellites and SNPs largely agree, however a few differences are apparent with SNPs identifying more discrete population subdivision. Our findings suggest management at the spatial scales and boundaries identified in this study will necessitate international and national cooperation to conserve S. lewini populations.

Regional-scale genetic differentiation of the stony coral Desmophyllum dianthus in the southwest Pacific Ocean is consistent with regional-scale physico-chemical oceanography

Deep-sea corals are diverse and abundant in New Zealand’s EEZ and the southwest Pacific Ocean. We assessed genetic diversity and gene flow of the deep-sea scleractinian (stony cup coral) Desmophyllum dianthus in five areas (Kermadec Ridge, Louisville Seamount Chain, Chatham Rise, Campbell Plateau, Macquarie Ridge), and applied dispersal kernels estimated from drifters observations and seascape genetics to compare with observed connectivity patterns and regional physico-chemical data. We observed pronounced between-region genetic differentiation, high levels of self-recruitment, but also high connectivity between distant sites (e.g., at the Kermadec Ridge inside the New Zealand EEZ, and the Louisville Seamount Chain outside the New Zealand EEZ). Genetic diversity was marginally highest at the Kermadec Ridge, whilst populations on the Chatham Rise showed evidence of unique genetic diversity that may be driven by converging ocean currents. Overall, patterns of genetic connectivity were consistent with oceanographic predictions of dispersal routes. Seascape genetic analyses indicated that environmental variables most often related to physical seafloor habitat characteristics were important predictors of regional-scale genetic differentiation of D. dianthus. Our research shows that current spatial closures within the New Zealand EEZ and surrounding high seas areas do not encompass the extent of genetic diversity and connectivity for D. dianthus, which parallels research for other deep-sea taxa in the region. Future measures implemented to protect deep-sea coral biodiversity require consideration of complex connectivity patterns and migration routes amongst taxa, at various spatial scales. This study demonstrates that a combined gene flow, seascape genetics and dispersal kernel modelling approach can provide a robust evaluation of connectivity in deep-sea environments to inform management decision making at the scale of the southwest Pacific Ocean.

Kilometer-Scale Larval Dispersal Processes Predict Metapopulation Connectivity Pathways for Paramuricea biscaya in the Northern Gulf of Mexico

Fine-scale larval dispersal and connectivity processes are key to species survival, growth, recovery and adaptation under rapidly changing disturbances. Quantifying both are required to develop any effective management strategy. In the present work, we examine the dispersal pattern and potential connectivity of a common deep-water coral, Paramuricea biscaya, found in the northern Gulf of Mexico by evaluating predictions of physical models with estimates of genetic connectivity. While genetic approaches provide estimates of realized connectivity, they do not provide information on the dispersal process. Physical circulation models can now achieve kilometer-scale resolution sufficient to provide detailed insight into the pathways and scales of larval dispersal. A high-resolution regional ocean circulation model is integrated for 2015 and its advective pathways are compared with the outcome of the genetic connectivity estimates of corals collected at six locations over the continental slope at depths comprised between 1,000 and 3,000 m. Furthermore, the likely interannual variability is extrapolated using ocean hindcasts available for this basin. The general connectivity pattern exhibits a dispersal trend from east to west following 1,000 to 2,000-m isobaths, corresponding to the overall westward near-bottom circulation. The connectivity networks predicted by our model were mostly congruent with the estimated genetic connectivity patterns. Our results show that although dispersal distances of 100 km or less are common, depth differences between tens to a few hundred meters can effectively limit larval dispersal. A probabilistic graphic model suggests that stepping-stone dispersal mediated by intermediate sites provides a likely mechanism for long-distance connectivity between the populations separated by distances of 300 km or greater, such as those found in the DeSoto and Keathley canyons.

Fine-grained habitat-associated genetic connectivity in an admixed population of mussels in the small isolated Kerguelen Islands

Reticulated evolution -i.e. secondary introgression / admixture between sister taxa-is increasingly recognized as playing a key role in structuring infra-specific genetic variation and revealing cryptic genetic connectivity patterns. When admixture zones coincide with ecological transitions, the connectivity patterns often follow environmental variations better than distance and introgression clines may easily be confounded with local adaptation signatures. The Kerguelen mussels is an ideal system to investigate the potential role of admixture in enhancing micro-geographic structure, as they inhabit a small isolated island in the Southern Ocean characterized by a highly heterogeneous environment. Furthermore, genomic reticulation between Northern species (M. edulis, M. galloprovincialis and M. trossulus) and Southern species (M. platensis: South America and the Kerguelen Islands; and M. planulatus: Australasia) has been suspected. Here, we extended a previous analysis by using targeted-sequencing data (51,878 SNPs) across the three Northern species and the Kerguelen population. Spatial structure in the Kerguelen was then analyzed with a panel of 33 SNPs, including SNPs that were more differentiated than the genomic average between Northern species (i.e., ancestry-informative SNPs). We first showed that the Kerguelen lineage splitted very shortly after M. edulis and M. galloprovincialis initiated speciation, and it subsequently experienced admixture with the three Northern taxa. We then demonstrated that the Kerguelen mussels were significantly differentiated over small spatial distance, and that this local genetic structure was associated with environmental variations and mostly revealed by ancestry-informative markers. Simulations of admixture in the island highlight that genetic-environment associations can be better explained by introgression clines between heterogeneously differentiated genomes than by adaptation.

Barriers and corridors of gene flow in an urbanized tropical reef system.

Information about the distribution of alleles among marine populations is critical for determining patterns of genetic connectivity that are essential in modern conservation planning. To estimate population connectivity in Singapore's urbanized equatorial reef system, we analysed single nucleotide polymorphisms (SNPs) from two species of reef‐building corals with distinct life histories. For Porites sp., a broadcast‐spawning coral, we found cryptic lineages that were differentially distributed at inshore and central‐offshore sites that could be attributed to contemporary surface current regimes. Near panmixia was observed for Pocillopora acuta with differentiation of colonies at the farthest site from mainland Singapore, a possible consequence of the brooding nature and relatively long pelagic larval duration of the species. Furthermore, analysis of recent gene flow showed that 60–80% of colonies in each population were nonmigrants, underscoring self‐recruitment as an important demographic process in this reef system. Apart from helping to enhance the management of Singapore's coral reef ecosystems, findings here pave the way for better understanding of the evolution of marine populations in South‐East Asia.

A portfolio of climate-tailored approaches to advance the design of marine protected areas in the Red Sea.

Intensified coastal development is compromising the health and functioning of marine ecosystems. A key example of this is the Red Sea, a biodiversity hotspot subjected to increasing local human pressures. While some marine‐protected areas (MPAs) were placed to alleviate these stressors, it is unclear whether these MPAs are managed or enforced, thus providing limited protection. Yet, most importantly, MPAs in the Red Sea were not designed using climate considerations, likely diminishing their effectiveness against global stressors. Here, we propose to tailor the design of MPAs in the Red Sea by integrating approaches to enhance climate change mitigation and adaptation. First, including coral bleaching susceptibility could produce a more resilient network of MPAs by safeguarding reefs from different thermal regions that vary in spatiotemporal bleaching responses, reducing the risk that all protected reefs will bleach simultaneously. Second, preserving the basin‐wide genetic connectivity patterns that are assisted by mesoscale eddies could further ensure recovery of sensitive populations and maintain species potential to adapt to environmental changes. Finally, protecting mangrove forests in the northern and southern Red Sea that act as major carbon sinks could help offset greenhouse gas emissions. If implemented with multinational cooperation and concerted effort among stakeholders, our portfolio of climate‐tailored approaches may help build a network of MPAs in the Red Sea that protects more effectively its coastal resources against escalating coastal development and climate instability. Beyond the Red Sea, we anticipate this study to serve as an example of how to improve the utility of tropical MPAs as climate‐informed conservation tools.

Genomic phylogeography of the White-crowned Manakin Pseudopipra pipra (Aves: Pipridae) illuminates a continental-scale radiation out of the Andes

The complex landscape history of the Neotropics has generated opportunities for population isolation and diversification that place this region among the most species-rich in the world. Detailed phylogeographic studies are required to uncover the biogeographic histories of Neotropical taxa, to identify evolutionary correlates of diversity, and to reveal patterns of genetic connectivity, disjunction, and potential differentiation among lineages from different areas of endemism. The White-crowned Manakin (Pseudopipra pipra) is a small suboscine passerine bird that is broadly distributed through the subtropical rainforests of Central America, the lower montane cloud forests of the Andes from Colombia to central Peru, the lowlands of Amazonia and the Guianas, and the Atlantic forest of southeast Brazil. Pseudopipra is currently recognized as a single, polytypic biological species. We studied the effect of the Neotropical landscape on genetic and phenotypic differentiation within this species using genomic data derived from double digest restriction site associated DNA sequencing (ddRAD), and mitochondrial DNA. Most of the genetic breakpoints we identify among populations coincide with physical barriers to gene flow previously associated with avian areas of endemism. The phylogenetic relationships among these populations imply a novel pattern of Andean origination for this group, with subsequent diversification into the Amazonian lowlands. Our analysis of genomic admixture and gene flow reveals a complex history of introgression between some western Amazonian populations. These reticulate processes confound our application of standard concatenated and coalescent phylogenetic methods and raise the question of whether a lineage in the western Napo area of endemism should be considered a hybrid species. Lastly, analysis of variation in vocal and plumage phenotypes in the context of our phylogeny supports the hypothesis that Pseudopipra is a species-complex composed of at least 8, and perhaps up to 17 distinct species which have arisen in the last ~2.5 Ma.

Large-scale genetic structure and diversity of Arctic rainbow smelt Osmerus dentex Steindachner et Kner, 1870 throughout its distributional range based on microsatellites

Arctic rainbow smelt Osmerus dentex is one of the most abundant fish species widely distributed in the NW Pacific and Arctic seas. Studying this species can contribute to understanding the microevolutionary processes of the Arctic fauna in unstable climatic conditions and new habitats. However, little is known about the genetic structure and the mechanisms underlying its population dynamics. Ten microsatellite loci were used to genotype 822 individuals in 20 locations throughout a large part of the species’ range in the Sea of Japan, Sea of Okhotsk, Bering, Kara, and White seas (across more than 11,000 km). O. dentex displayed substantial levels of genetic differentiation (overall FST = 0.067, RST = 0.091) and STRUCTURE identified eight distinct clusters. The significant regional variation was demonstrated in both genetic diversity and population structure, most notably between Arctic and Pacific basins. On a regional scale, contrasting patterns were revealed with limited gene flow between populations of the Arctic region (FST = 0.117) and high gene flow between the Bering Sea (FST = 0.017) or Sea of Okhotsk (FST = 0.031), which were probably associated with differences in larval distribution from the spawning grounds due to different oceanographic conditions of the studied areas. These results demonstrate the effect of local contemporary forces in shaping different patterns of genetic connectivity and diversity within O. dentex.

An investigation of genetic connectivity shines a light on the relative roles of isolation by distance and oceanic currents in three diadromous fish species

Understanding connectivity is crucial for the effective conservation and management of biota. However, measuring connectivity directly is challenging and it is often inferred based on assumptions surrounding dispersal potential, such as environmental history and species life history traits. Genetic tools are often underutilised, yet can infer connectivity reliably. Here, we characterise and compare the genetic connectivity and genetic diversity of three diadromous Australian fish species: common galaxias (Galaxias maculatus), tupong (Pseudaphritis urvillii) and Australian grayling (Prototroctes maraena). For each species, we investigate the extent of genetic connectivity across a study region in south-eastern Australia (~700 km). We further determine the potential roles of contemporary ocean currents in shaping the patterns of genetic connectivity observed. Individuals across multiple rivers were sampled and &gt;3000 single nucleotide polymorphisms were genotyped for each species. We found differences in genetic connectivity for the three species: common galaxias were highly connected, and Australian grayling and tupong exhibited patterns of isolation by distance. The degree of genetic connectivity for tupong and Australian grayling appeared unrelated to oceanic currents. This study indicates that the degree of connectivity for different diadromous species can vary greatly despite broadly similar life history strategies, highlighting the potential value of genetic tools for informing species-specific management plans.

Genetic patterns of the corals Euphyllia glabrescens and Lobophyllia corymbosa across the Indonesian Archipelago

Abstract. Jompa J, Umar W, Yusuf S, Tassakka ACM, Limmon GV, Rahmi, Putri AP, Halwi, Tamti H, Moore AM. 2020. Genetic patterns of the corals Euphyllia glabrescens and Lobophyllia corymbosa across the Indonesian Archipelago. Biodiversitas 21: xxxx. Scleractinian corals can reproduce in several ways, with two main sexual reproduction modes known as brooding and broadcast spawning. In this study, we described patterns of genetic variation within and connectivity between coral populations in western Indonesia (Seribu Archipelago), central Indonesia (Spermonde Archipelago), and eastern Indonesia (Ambon). We sampled two readily identifiable corals popular in the marine aquarium trade, one species widely reported as a brooder (Euphyllia glabrescens), the other as a broadcast spawner (Lobophyllia corymbosa). The mitochondrial COI genome was amplified for 117 samples. Within-population genetic variation was high, especially at the eastern Indonesia (Ambon) site. The genetic connectivity patterns were similar for the two corals, with high connectivity between the Seribu and Spermonde Archipelagos (despite a geographical separation of more than 1,000 km) and a lack of connectivity between these two sites and Ambon. These results indicate a potential barrier to gene flow between coral populations in western/central Indonesia and those to the east of Sulawesi Island.

Large-scale assessment of genetic diversity and population connectivity of Amazonian jaguars (Panthera onca) provides a baseline for their conservation and monitoring in fragmented landscapes

Jaguar population genetics has so far not been investigated on a broad scale in the Amazon rainforest, which constitutes the largest remaining block of continuous habitat for the species. Given its size, it serves not only as a stronghold but also as a reference for jaguar conservation genetics, against which fragmented landscapes can be compared. We assessed genetic diversity and population structure of Amazonian jaguars using 11 microsatellite loci and performed comparative analyses incorporating available data from two other South American biomes (Pantanal and Atlantic Forest) in which the species has faced different amounts of habitat loss and fragmentation. Using the largest genetic data set assembled to date for jaguars (n = 190), we observed that all diversity indices were consistently higher for the Amazonian population, with no genetic subdivision detected in that region, indicating large-scale connectivity across >3000 km. In contrast, we corroborate the inference of anthropic-driven genetic structure and bottlenecks for two Atlantic Forest populations. Our results indicate that the Amazon is a critically important stronghold for jaguars, comprising a highly diverse, panmictic population that allows a glimpse into the patterns of genetic connectivity that characterized this species prior to human intervention. In contrast, the Atlantic Forest populations jointly still retain considerable levels of genetic diversity, but this is currently partitioned among isolated fragments that are increasingly subjected to heavy anthropic disturbance. These results have important implications for jaguar conservation planning, highlighting the critical condition of Atlantic Forest populations and providing a genetic baseline to which they can be compared.

High genetic connectivity in a gastropod with long-lived planktonic larvae

AbstractGenetic connectivity plays a crucial role in shaping the geographic structure of species. Our aim in this study was to explore the pattern of genetic connectivity in Bursa scrobilator, an iconic marine caenogastropod with long-lived pelagic larvae. Our study was based on the analysis of DNA sequence data for the 658-bp barcoding fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene. This is the largest DNA sequence dataset assembled to date for B. scrobilator. These data confirm that the two recently described subspecies B. scrobilator scrobilator (Linnaeus, 1758), from the Mediterranean and Macaronesia, and B. s. coriacea (Reeve, 1844), from West Africa, constitute two evolutionarily significant units (ESUs). We found that for the nominal subspecies, the variation in morphology (shell, radula and gross anatomy) and DNA sequences was not geographically structured, and this agrees with what we would expect in a species with high connectivity at the larval stage. The divergence between the two subspecies cannot be easily explained by isolation by distance, and we would argue that one or more extrinsic factors may have played a role in isolating the two ESUs and maintaining that isolation.