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- Machine learning approaches to assess microendemicity and conservation
risk in cave-dwelling arachnofauna-
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Abstract: Abstract The biota of cave habitats faces heightened conservation risks, due to geographic isolation and high levels of endemism. Molecular datasets, in tandem with ecological surveys, have the potential to precisely delimit the nature of cave endemism and identify conservation priorities for microendemic species. Here, we sequenced ultraconserved elements of Tegenaria within, and at the entrances of, 25 cave sites to test phylogenetic relationships, combined with an unsupervised machine learning approach for detecting species. Our analyses identified clear and well-supported genetic breaks in the dataset that accorded closely with morphologically diagnosable units. Through these analyses, we also detected some previously unidentified, potential cryptic morphospecies. We then performed conservation assessments for seven troglobitic Israeli species of this genus and determined five of these to be critically endangered.
PubDate: 2024-08-03
- Absence of genetic structure among ecologically diverse populations
indicate high plasticity in a pantropical seabird-
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Abstract: Abstract Genotype and phenotype in mobile organisms can be defined by various factors such as environmental, biological and geographical. Brown noddies Anous stolidus are pan-tropical seabirds breeding at different times, with migratory and resident populations in six islands throughout 20° of latitude in the Southwestern Atlantic Ocean. If environmental heterogeneity plays a key role in their population biology, we would expect significant genetic structure among colonies. However, absence of genetic structure between phenotypically different populations could play a scenario of ecological plasticity. To test these hypotheses, we used a model-based integrative approach combining genetic (mtDNA and ultraconserved elements) and morphological data of the brown noddy (n = 122) along with environmental variables and isotopic niches. We uncovered low levels of genetic structure, with 16 haplotypes for mtDNA and a signal of an ancient population expansion. Ultraconserved elements indicated that all colonies belong to the same genetic population (K = 1) and revealed substantial endogamy. However, phenotype differed both by biometric measures and isotopic niches between most pairs of populations. Although individuals from the northernmost colony are larger than the others, they are genetically similar, indicating a wide reaction norm for this species. Our results indicate the Southwestern Atlantic populations of the brown noddy are panmictic, but ecologically and morphologically diverse.
PubDate: 2024-08-01
- Genomic patterns of native palms from the Leeward Antilles confirm
single-island endemism and guide conservation priorities-
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Abstract: Abstract Systematic study of the palm (Arecaceae) flora from the Leeward Antilles marked both Sabal antillensis and Sabal lougheediana as endemic to Curaçao and Bonaire respectively. Although both species are emergent, obvious and charismatic elements of the Antillean flora, they were only described within the last decade. Sabal lougheediana is in demographic crisis as a result of constant ungulate pressure prohibiting seedling establishment, while S. antillensis is thriving as a result of careful management. Given the surprisingly recent discovery of these two species, and the severity of the conservation concern, genomic data can help inform whether these taxa are in fact well-circumscribed species, and help to guide further conservation actions. To investigate genomic diversity, we employed RADSeq data from samples throughout the range of both species. Results show significant genetic distance and fixation between the two taxa as currently circumscribed, as well as reduced genetic diversity and increased inbreeding in both species. Multivariate analysis of genetic distance and Bayesian clustering analysis both show clear and significant separation of the two taxa. Parallel assay of ex situ collections informs how future development of germplasm reserves can help support conservation of both species. We provide recommendations to help conserve these two unique and distinct species.
PubDate: 2024-08-01
- Genetic structure of restored Brook Trout populations in the Southern
Appalachian Mountains indicates successful reintroductions-
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Abstract: Abstract Wildlife reintroduction is an important conservation tool for threatened species, yet identifying appropriate source populations poses a challenge. In particular, the possibility of outbreeding depression is cited as a constraint limiting the range of candidate source populations for translocation. When multiple source lineages are mixed during reintroduction, genetic monitoring is necessary to evaluate whether sources contribute equally to subsequent generations and whether they are interbreeding as expected. Moreover, statistical analysis of genetic data should account for complex life histories that might affect the timescale of admixture and genetic drift. Here, we use samples collected over a 23-year period and a stochastic age-structured model to analyze the genetic mixing process in reintroduced Brook Trout (Salvelinus fontinalis) populations in the Southern Appalachians. Each restored population was seeded with two to three source populations. Previous research inferred reproductive isolation between source populations leading to a proposal of splitting the species into multiple taxa. In contrast, we found patterns of ancestry that were consistent with random mating and no advantage for one source lineage over any other. Brook Trout from different source streams are mixing as expected in the restoration sites. This result does not support the hypothesis that Brook Trout in the Southern Appalachian Mountains includes several distinct species. Mixing different sources from the same watershed seems to be an effective way to increase genetic diversity of reintroduced populations while minimizing risk to source populations.
PubDate: 2024-08-01
- Admixture and reproductive skew shape the conservation value of ex situ
populations of the Critically Endangered eastern black rhino-
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Abstract: Abstract Small populations of endangered species risk losing already eroded genetic diversity, important for adaptive potential, through the effects of genetic drift. The magnitude of drift can be mitigated by maximising the effective population size, as is the goal of genetic management strategies. Different mating systems, specifically those leading to reproductive skew, exacerbate genetic drift by distorting contributions. In the absence of an active management strategy, reproductive skew will have long-term effects on the genetic composition of a population, particularly where admixture is present. Here we examine the contrasting effects of conservation management strategies in two ex situ populations of the Critically Endangered eastern black rhino (Diceros bicornis michaeli), one managed as a semi-wild population in South Africa (SAx), and one managed under a mean-kinship breeding strategy in European zoos. We use molecular data to reconstruct pedigrees for both populations and validate the method using the zoo studbook. Using the reconstructed pedigree and studbook we show there is male sex-specific skew in both populations. However, the zoo’s mean-kinship breeding strategy effectively reduces reproductive skew in comparison to a semi-wild population with little genetic management. We also show that strong male reproductive skew in SAx has resulted in extensive admixture, which may require a re-evaluation of the population’s original intended role in the black rhino meta-population. With a high potential for admixture in many ex situ populations of endangered species, molecular and pedigree data remain vital tools for populations needing to balance drift and selection.
PubDate: 2024-08-01
- Isolation, small population size, and management influence inbreeding and
reduced genetic variation in K’gari dingoes-
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Abstract: Abstract Small island populations are vulnerable to genetic decline via demographic and environmental stochasticity. In the absence of immigration, founder effects, inbreeding and genetic drift are likely to contribute to local extinction risk. Management actions may also have a greater impact on small, closed populations. The demographic and social characteristics of a species can, however, delay the impact of threats. K’gari, a ~ 1 660 km2 island off the Australian east coast and UNESCO World Heritage Site (Fraser Island 1842–2023), supports an isolated population of approximately 70–200 dingoes that represent an ideal opportunity to explore the small island paradigm. To examine temporal and spatial patterns of genetic diversity in this population we analysed single nucleotide polymorphism (SNP) genotype data (72 454 SNPS) for 112 K’gari dingoes collected over a 25-year period (1996 to 2020). Genetic diversity was lower in K’gari dingoes than mainland dingoes at the earliest time point in our study and declined significantly following a management cull in 2001. We did not find any spatial genetic patterns on the island, suggesting high levels of genetic connectivity between socially discrete packs. This connectivity, combined with the social structure and behaviour of dingoes, may act in concert to buffer the population from the impacts of genetic drift in the short term. Nevertheless, a general decline in genetic variation via inbreeding and drift has occurred over the past 20 years which we suggest should be considered in any future management planning for the population. Monitoring patterns of genetic variation, together with a clearer understanding of the social ecology of K’gari dingoes, will aid in the development of measurable genetic targets set over ecologically meaningful timelines, and help ensure continued survival of this culturally important population.
PubDate: 2024-08-01
- Loss of genetic diversity and isolation by distance and by environment in
populations of a keystone ungulate species-
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Abstract: Abstract Adaptive genetic and neutral variations are essential for maintaining population viability in changing environmental conditions. Habitat loss and fragmentation can be reflected in the patterns of genetic variation in the populations. White-lipped peccaries (WLPs, Tayassu pecari) are wide-ranging Neotropical ungulates with important ecological roles in the ecosystem suffering local extinctions worldwide. Here, we used a RAD-seq protocol to genotype 192 individuals. After filtering, we identified sets of SNP markers (ranging from 147 to 151,792 SNPs) to assess the genetic diversity and population structure of WLPs from Pantanal, Cerrado, and Atlantic Forest in Brazil. We found signals of loss (θw < θπ) and lower genetic diversity (allelic richness, nucleotide diversity, and observed and expected heterozygosities) in the Central Cerrado and Atlantic Forest populations. Principal Component Analysis (PCA) and admixture analyses (NGSAdmix) using genome-wide and neutral SNP data sets showed three major genetic clusters according to the biomes. Multiple matrix regression with randomization (MMRR) analysis found an isolation-by-distance pattern explaining the neutral genetic differentiation. We used Latent Factor Mixed Models (LFMM) and Redundancy Analysis (RDA) to identify candidate SNPs involved in different biological processes, such as metabolism and immune and neuronal responses, mainly associated with temperature and precipitation variables. We found an adaptive population genetic structure, suggesting three adaptive units with significant patterns of isolation-by-distance and isolation-by-environment. Our results highlighted the importance of conservation strategies for maintaining the genetic diversity of WLP populations. Furthermore, conservation plans and translocation programs should preserve and consider the adaptive variation.
PubDate: 2024-08-01
- Early detection of rare and elusive endangered species using environmental
DNA: a case study for the Eurasian otter and the white-clawed crayfish in
northwestern Italy-
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Abstract: Abstract Monitoring, management and conservation of rare and elusive species often requires early detection of individuals, especially for re-introduced and endangered taxa. Environmental DNA (eDNA) approaches can enhance the detection power of traditional biomonitoring methods for low-density, newly-established populations. In this study, we used species-specific Real Time PCR TaqMan assays to assess the presence of two endangered freshwater species, the white-clawed crayfish Austropotamobius pallipes and the Eurasian otter Lutra lutra at eight sites in four river catchments in Liguria (northwestern Italy). The Eurasian otter was considered extinct in the study area since the 1980s. However, recent, although scattered sightings indicated a recolonisation by a few individuals. The white-clawed crayfish populations declined drastically and became increasingly dispersed in the western part of Liguria. Our eDNA analysis confirmed the presence of both species in some of the selected rivers and detected Eurasian otter DNA where the species was not recorded through traditional monitoring methods. This study confirms eDNA-based monitoring approaches as valuable tools to assess the presence of rare and elusive species and help implement protection plans at a local scale.
PubDate: 2024-08-01
- Population genetics of caribou in the Alaska-Yukon border region:
implications for designation of conservation units and small herd
persistence-
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Abstract: Abstract Better knowledge of genetic relationships between the Fortymile caribou herd and its neighbors is needed for conservation decision-making in Canada. Here, we contribute the first fine-scale analysis of genetic population structure in nine contiguous caribou herds at the geographic boundaries between Barren-ground and Northern Mountain caribou, and at the Alaska-Yukon border. Using pairwise differentiation metrics, STRUCTURE, and discriminant analysis of principal components (DAPC) to analyze 15 microsatellite loci in 379 caribou, we found complex patterns of genetic differentiation. The Fortymile was the only herd assigned to more than one genetic cluster, indicative of its history as a larger herd whose range expansions and gene flow to other herds were likely important to maintaining diversity across a functioning genetic metapopulation. Some small herds (Chisana, Klaza, and White Mountains) were genetically distinct, while others (Hart River, Clear Creek, Mentasta) exhibited little differentiation from herds they occasionally overlap, including herds assigned to different conservation units (DUs). This genetic connectivity does not result from demographic connectivity, as episodic contact during rut, rather than herd switching, is the likely mechanism. Unusually, one small herd (White Mountains) maintained genetic differentiation despite rut overlap with Fortymile. Our data reveal that some herds with different ecological and behavioral attributes are demographically independent but nonetheless genetically connected. Thus, we suggest that managing caribou for an appropriate level of genetic connectivity, while also supporting herd persistence, will be essential to conserve caribou genetic diversity in the region.
PubDate: 2024-08-01
- Genetic structure and diversity of semi-captive populations: the anomalous
case of the Asian elephant-
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Abstract: Abstract Wild species living in captivity are subject to loss of genetic diversity, inbreeding depression, and differentiation among populations. Only very few species have been under human care for centuries but have not been selectively bred, have free-ranging movements most of the time, and retain porous barriers to gene flow between wild and captive populations. Such captive populations are expected to retain high levels of genetic diversity and anthropogenic factors should result in a limited genetic differentiation from wild populations. Asian elephants have been trained and used by humans for at least 4000 years as war animals, mounts of kings and draught animals. In Myanmar and Laos, elephants are still being used for hauling timber in the forest while retaining traditional management practices including seasonal release, free mating and movement. However, habitat fragmentation, isolation and reduced gene flows are threatening both semi-captive and wild pools. We genotyped 167 semi-captive elephants from Laos and Myanmar using a panel of 11 microsatellite loci to estimate the genetic diversity and population structure. We found that elephants of both countries presented high levels of genetic diversity and a low degree of inbreeding, if any. This agrees with the expected high level of genetic diversity in semi-captive populations. We found a weak differentiation along a geographical gradient from southern Laos to northern Myanmar but no differentiation between wild-caught and captive-born pools. The potential value for conservation of a large population of semi-captive elephants has been recognized but the conservation community has yet to fully explore the potential role semi-captive elephants could play in maintaining gene flows.
PubDate: 2024-08-01
- Genomic and common garden data reveal significant genetic differentiation
in the endangered San Fernando Valley spineflower Chorizanthe parryi var.
fernandina-
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Abstract: Abstract San Fernando Valley spineflower (Chorizanthe parryi var. fernandina [S. Watson] Jeps.) (Polygonaceae) is an herbaceous annual plant, endemic to California, and until rediscovered in 1999 had been thought to be extinct for almost seven decades. Historically documented at 10 locations, it currently persists at 2, separated by approximately 27 km. State listed as endangered, a description of its genetic diversity and structure is of conservation interest. After determining a lack of variation in ploidy, we examined genetic variation from samples within both populations: a common garden study for potentially adaptive genetic variation in selected growth and phenological traits and analysis of single nucleotide polymorphisms identified through restriction-site associated DNA sequencing. Both measures indicated that this highly restricted taxon nevertheless harbors substantial levels of genetic diversity and has significant between- and within-population genetic structure. Combining approaches from population genomics and common garden studies provided more insight into the patterns and basis of genetic diversity than is typical for studies of non-model species. Although local adaptation was not specifically studied (i.e., via reciprocal transplant studies), the differences determined from these two independent lines of evidence indicate that mixing gene pools between populations is not recommended at this time. Further, with significant differences revealed among subpopulations, we caution against mixing genotypes across subpopulations for the most part, and without much more evidence that this would not pose a risk of outbreeding depression. The importance of supporting pollinator health and diversity is highlighted. With genetic diversity—particularly with an annual species—being dynamic, fluctuating with the usual processes and with contributions from the soil seedbank, we recommend periodic resampling to monitor genetic diversity and structure. Climate change is anticipated to contribute to this variability.
PubDate: 2024-08-01
- Genetic support for discrete conservation units of the fossorial rodent
Geomys pinetis-
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Abstract: Abstract Knowledge of the population genetic structure and diversity of at-risk species is essential to accurately evaluate population viability and define units for conservation and management. The southeastern pocket gopher (Geomys pinetis) is a fossorial rodent native to the imperiled longleaf pine savannas of the southeastern United States. Its recent decline has made it a species of ‘high conservation concern’ by state agencies. Previous phylogenetic analyses suggested two distinct lineages within the species occurring east (G. p. pinetis) and west (G. p. mobilensis) of the Apalachicola-Chattahoochee-Flint River (ACF) Basin, a phylogeographic break for many species. However, little is known about the genetic substructure within each region. We examined neutral and putatively adaptive variation in 9373 single nucleotide polymorphisms (SNPs) to assess the extent of genetic structure across the species' geographic range. We confirmed significant genetic divergence of populations east–west of the ACF Basin, predating the Last Glacial Maximum, supporting the presence of two evolutionary independent lineages. Our results indicate additional strong genetic substructuring within each lineage and possible non-neutral variation across latitudes. Given the high degree of genetic differentiation and lack of evidence for secondary contact among populations within the ACF Basin, we recommend that G. pinetis be managed as two conservation units corresponding to distinct lineages representing G. pinetis and G. mobiliensis.
PubDate: 2024-07-30
- Genetic diversity in the traditional cultivars and wild ancestor of
near-threatened Japanese iris (Iris ensata Thunb.)-
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Abstract: Abstract Wild relatives of cultivars are crucial sources of genetic variation for further enhancement, yet they face potential threats due to contemporary environmental changes. Iris ensata var. spontanea, a wild progenitor of the Japanese iris cultivars (I. ensata var. ensata), is extensively cultivated in Japanese gardens, is distributed across mesic meadows and wetlands in Japan and East Asia. This species is currently threatened owing to habitat loss linked to land use alterations. We assessed genetic diversity and phylogenetic relationships in 32 wild accessions and the 14 principal Edo Group of Japanese iris cultivars, originally bred during the Edo period (1600–1868). In the phylogenetic tree, the cultivars formed a cluster with low inbreeding coefficients, suggesting a singular origin and interbreeding between the genetically distinct accessions. Conversely, wild accessions exhibited greater overall genetic diversity and higher inbreeding coefficients than cultivars, indicating frequent inbreeding within divergent natural populations. Our findings highlight the distinct genetic reservoirs of both wild accessions and Edo cultivars, although the former may face inbreeding challenges. Urgent conservation action is needed to ensure the genetic diversity of wild populations as natural resources.
PubDate: 2024-07-18
- Population genetic structure of the European pond turtle (Emys
orbicularis) at the northern edge of the Pannonian Basin-
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Abstract: Abstract Populations of plants and animals at the edge of a species’ range may exhibit lower genetic diversity due to a combination of historical (e.g., postglacial dispersal) and contemporary (e.g., low effective population size, strong genetic drift or bottlenecks) processes. In this study, we analysed the genetic structure of populations of the European pond turtle (Emys orbicularis) in the northern part of the Pannonian Basin (Slovakia, Hungary, Austria), which represents the edge of the species’ range. Using mitochondrial DNA (mtDNA) and microsatellite markers, we aimed to assign individuals and populations into phylogeographic lineages and to determine genetic variation and population structure. Our study revealed that most individuals from natural populations belong to mtDNA lineage II (widely distributed haplotype IIa, and likely endemic haplotypes IIl and IIo), which is typical for the whole Pannonian region. However, non-native haplotypes were detected in one Slovak population (haplotype Ib) and in the Austrian Donau Auen National Park (haplotype IVa). Microsatellite markers revealed high variability comparable to that in other parts of the range, suggesting that marginal populations may not necessarily have reduced genetic diversity. A genetically mixed population was found in the Donau Auen National Park, consisting of turtles belonging to mtDNA lineage II (taxonomically assessed as subspecies E. orbicularis orbicularis) and lineage IV (taxonomically assessed as E. orbicularis hellenica), which is native to the circum-Adriatic region. The admixture suggests intense hybridization and introgression between the two lineages (subspecies).
PubDate: 2024-07-18
- Genetic assessment and monitoring of wild, captive, and reintroduced
northern leopard frog populations-
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Abstract: Abstract The northern leopard frog (Lithobates pipiens) has undergone dramatic declines in population size and range over recent decades in western Canada and the United States. In British Columbia, only a single population remains at the Creston Valley Wildlife Management Area. Yet, the continuing viability of this population is uncertain. In this paper, the current genetic structure of northern leopard frog populations in western Canada was assessed using microsatellite markers. Historical samples from the extinct population of Fort Steele in British Columbia were compared with the Creston Valley population to understand changes in population genetic parameters over time. Genotypic data from four populations (Creston Valley, Drain K, Prince Spring, and Cypress Hill) sampled in 2004 and 2019 were compared. To evaluate changes in the genetic diversity of the Creston Valley population over time, allelic richness and expected heterozygosity of the population were compared at three time points using genotypes from 2000, 2004, and 2019. Northern leopard frog populations in western Canada showed high genetic differentiation, with genetic diversity decreasing from east to west. Although there weren’t notable changes in genetic parameters between 2004 and 2019, there was evidence of a decline in diversity between 2000 and 2019. The extinct population of Fort Steele had private alleles, while the current Creston Valley population did not, suggesting a genetic bottleneck in the Creston Valley population. Therefore, genetic rescue, specifically for the endangered Creston Valley population, can be considered as an action to support recovery. Additionally, continued genetic monitoring will help in the effective management of the species by providing information on the success of conservation actions.
PubDate: 2024-07-16
- Deep genetic divergence underlies within-island eco-morphological
variation in the endangered day gecko Phelsuma borbonica: implications for
conservation-
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Abstract: Abstract The day gecko Phelsuma borbonica displays marked differences in coloration and occupies a variety of habitats across its very small range on the volcanic oceanic island of Reunion in the southwestern Indian Ocean. Such differences might reflect geographic and ecological divergence and thus be associated with an underlying genetic differentiation. We examined the partitioning of genetic diversity in Phelsuma borbonica across Reunion at a very small spatial scale (< 10 km) using mtDNA and nuDNA sequences, along with microsatellite genotype data. This study provides an account of the evolutionary history of Phelsuma borbonica, along with a quantification of effective population sizes, which constitute important information for the conservation of this endangered species, which may represent a previously unrecognized case of incipient speciation. We found that populations of Phelsuma borbonica are genetically strongly differentiated, highlighting historically low levels of gene flow. Phylogenetic analyses suggest that Phelsuma borbonica reached its present range through two parallel southward expansions from an ancestral population located in the northern part of the island.
PubDate: 2024-06-24
- Conservation genetics of the endangered California Freshwater Shrimp
(Syncaris pacifica): watershed and stream networks define gene pool
boundaries-
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Abstract: Abstract Understanding genetic structure and diversity among remnant populations of rare species can inform conservation and recovery actions. We used a population genetic framework to spatially delineate gene pools and estimate gene flow and effective population sizes for the endangered California Freshwater Shrimp Syncaris pacifica. Tissues of 101 individuals were collected from 11 sites in 5 watersheds, using non-lethal tissue sampling. Single Nucleotide Polymorphism markers were developed de novo using ddRAD-seq methods, resulting in 433 unlinked loci scored with high confidence and low missing data. We found evidence for strong genetic structure across the species range. Two hierarchical levels of significant differentiation were observed: (i) five clusters (regional gene pools, FST = 0.38–0.75) isolated by low gene flow were associated with watershed limits and (ii) modest local structure among tributaries within a watershed that are not connected through direct downstream flow (local gene pools, FST = 0.06–0.10). Sampling sites connected with direct upstream-to-downstream water flow were not differentiated. Our analyses suggest that regional watersheds are isolated from one another, with very limited (possibly no) gene flow over recent generations. This isolation is paired with small effective population sizes across regional gene pools (Ne = 62.4–147.1). Genetic diversity was variable across sites and watersheds (He = 0.09–0.22). Those with the highest diversity may have been refugia and are now potential sources of genetic diversity for other populations. These findings highlight which portions of the species range may be most vulnerable to future habitat fragmentation and provide management consideration for maintaining local effective population sizes and genetic connectivity.
PubDate: 2024-06-16
DOI: 10.1007/s10592-024-01621-x
- The importance of understanding clonal structure for species listing and
recovery: case studies from the rare oconee bells (Shortia brevistyla and
Shortia galacifolia; Diapensiaceae) and the federally endangered bunched
arrowhead (Sagittaria fasciculata; Alismataceae)-
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Abstract: Abstract Understanding genetic structure in rare plant populations is essential to making informed decisions for recovery actions, particularly in species capable of clonal reproduction. Here, we present three case studies using microsatellites to assess clonal structure in rare plants: Northern Oconee bells (S. brevistyla (P.A. Davies) Gaddy) and Southern Oconee bells (Shortia galacifolia Torr & Gray) (Diapensiaceae); and bunched arrowhead (Sagittaria fasciculata E.O. Beal (Alismataceae)). We used six loci to genotype Shortia brevistyla (n = 62 ramets; three sites) and S. galacifolia (n = 111 ramets; seven sites) and five loci in Sagittaria fasciculata (n = 162 ramets; eight sites). Ramets were systematically mapped and sampled to allow for clonal assignment in a spatial context. All ramets for S. brevistyla were genetically identical across all loci, while S. galacifolia exhibited variation consistent with a mixed reproductive strategy. Sagittaria fasciculata also exhibited a mixed reproductive strategy with emphasis on clonality. Our data indicate that stem counts are not effective measures for recovery assessment in these species, and a more complex demographic monitoring protocol should be developed. Additional implications for conservation of these species are discussed, including a consideration for federal listing for Shortia brevistyla.
PubDate: 2024-06-01
DOI: 10.1007/s10592-024-01608-8
- Cross ocean-basin population genetic dynamics in a pelagic top predator of
high conservation concern, the oceanic whitetip shark, Carcharhinus
longimanus-
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Abstract: Abstract The oceanic whitetip shark, Carcharhinus longimanus, is a Critically Endangered, circumtropical, and highly migratory, pelagic shark. Yet, little information exists on its population genetic dynamics to guide conservation management practice. We present a first worldwide, mitochondrial and nuclear DNA assessment of the population genetic status of this imperiled species based on sequences of the complete mitochondrial control region (n = 173) and partial ND4 gene (n = 172), and genotypes from 12 nuclear microsatellites (n = 164). Statistically significant mitochondrial and nuclear DNA population genetic differentiation was detected across all marker datasets between Western Atlantic and Indo-Pacific oceanic whitetip sharks. Additionally, our data, combined with previously published, partial (701-base pairs) mitochondrial control region sequences from additional locations in the Atlantic and Indian Oceans, confirmed significant matrilineal population structure between the Western and Eastern Atlantic. The combined data also provisionally (i.e., with FST but not ΦST) indicated differentiation between Western North and Central-South Atlantic sharks, pointing to the need for further assessment in this region. Matrilineal differentiation was also detected between Indian and Pacific Ocean sharks via pairwise analyses, albeit with the ND4 gene sequence only (ΦST = 0.051; FST = 0.092). Limited sampling in the Pacific leaves open questions about the connectivity dynamics in this large region. Despite the presence of geographic population genetic structure, the mitochondrial data showed no evidence of across ocean basin phylogeographic lineages. A provisional assessment of mitochondrial and nuclear genetic diversity indicated the oceanic whitetip shark’s status falls in the middle to upper ranges compared to other shark species, potentially lending some optimism for the present adaptability and resiliency of this species if strong conservation measures are effectively implemented.
PubDate: 2024-06-01
DOI: 10.1007/s10592-023-01596-1
- Correction: Revisiting conservation units for the endangered mountain
yellow-legged frog species complex (Rana muscosa, Rana sierrae) using
multiple genomic methods-
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PubDate: 2024-04-19
DOI: 10.1007/s10592-024-01615-9
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