 Subjects -> CONSERVATION (Total: 128 journals)
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- Genetic differences among the Interior Highlands walleye (Sander vitreus)
with mitochondrial and nuclear markers indicate the need for updated
stocking practices-
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Abstract: Glacial cycles and pre-glacial drainage patterns have imbued the Interior Highlands of the United States with a rich suite of freshwater taxa and phylogroups. However, supplementation of sportfish from the Great Lakes into the waterbodies of this region, including the Missouri, Ouachita, Black, White, and Little Red River drainages, may have obscured phylogeographic patterns. Walleye (Sander vitreus), one of the most common sportfish in the eastern US, inhabit the Interior Highlands but their population genetic composition and structure in this region has received little attention. We examined the genetic composition of walleye (n = 643) in the Interior Highlands using microsatellite markers and a subsample (n = 188) with mitochondrial DNA and found significant genetic differences among walleye in our study area. Walleye from the Missouri, Ouachita, White, and Little Red drainages were most closely related to a Great Lakes reference sample, a common stocking source. However, the Black River, in the easternmost portion of the Interior Highlands, contained walleye with mitochondrial DNA that was closely related to walleye from the Eastern Highlands. The remainder of the study area drainages contained a mix of walleye groups, more closely related to Great Lakes rather than Highlands walleye but not definitively the product of stocking. Though managers have relied on mitochondrial markers for stock identification in the past, we recommend that walleye in regions receiving little research attention be analyzed with nuclear markers to better understand and preserve genetic diversity and that managers stock with local walleye only within the drainages that we identified as genetically distinct: Black, Missouri, and White/Little Red/Ouachita.
PubDate: 2023-06-01
- Landscape genetics identifies barriers to Natterjack toad metapopulation
dispersal-
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Abstract: Habitat fragmentation and loss reduce population size and connectivity, which imperils populations. Functional connectivity is key for species persistence in human-modified landscapes. To inform species conservation management, we investigated spatial genetic structure, gene flow and inferred dispersal between twelve breeding sites of the Natterjack toad (Bufo calamita); regionally Red-Listed as Endangered in Ireland. Spatial genetic structure was determined using both Bayesian and non-Bayesian clustering analysis of 13 polymorphic microsatellite loci genotyping 247 individuals. We tested the influence of geographic distance, climate, habitat, geographical features, and anthropogenic pressure on pairwise genetic distances between breeding sites using Isolation-by-distance and Isolation-by-resistance based on least-cost path and circuit theory models of functional connectivity. There was clear spatial structuring with genetic distances increasing with geographic distance. Gene flow was best explained by Isolation-by-resistance models with coniferous forestry plantations, bog, marsh, moor and heath, scrub, anthropogenic presence (Human Influence Index) and rivers (riparian density) identified as habitats with high resistance to gene flow while metapopulation connectivity was enhanced by coastal habitats (beaches, sand dunes and salt marshes) and coastal grassland. Despite substantial declines in census numbers over the past 15 years and its regional status as Endangered, the Natterjack toad population in Ireland retains high genetic diversity. If declines continue, maintaining habitat connectivity to prevent genetic erosion by management of coastal grasslands, pond construction and assisted migration through translocation will be increasingly important.
PubDate: 2023-06-01
- Whole genome re-sequencing uncovers significant population structure and
low genetic diversity in the endangered clouded apollo (Parnasssius
mnemosyne) in Sweden-
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Abstract: The clouded apollo (Parnassius mnemosyne) used to have a wide distribution in Fennoscandia. Recent population declines have, however, led to regional extinctions and in Sweden it is currently one of the most endangered butterflies, confined to three geographically separated metapopulations: Blekinge, Roslagen and Västernorrland. Especially the Blekinge population has declined dramatically and few imagines have been observed during recent census efforts (< 10 in some localities). The clouded apollo is subject to a species action plan which includes both habitat restorations and captive breeding to produce individuals for release and reintroductions. Here, we apply whole-genome resequencing of clouded apollo individuals collected in the three natural populations and the captive population in Sweden and apply population genomic approaches to get a better understanding of the genetic structure and levels of genetic diversity in the species. We find that the clouded apollo populations in the different geographic regions have similar, but comparatively low levels of genetic diversity and we find evidence for significant genetic differentiation between the northernmost population and the populations in southern Sweden. Additional analysis, including previously available mitochondrial data, unveil that a bi-directional re-colonization of Fennoscandia after the latest glacial maximum most likely is the explanation for the considerable differentiation between some Swedish populations. Finally, we find evidence for population sub-structure in one of the Swedish populations. The results provide insights into the genetic consequences of population size declines and fragmentation in general and provide important information for direct conservation actions for the clouded apollo in Sweden in particular.
PubDate: 2023-06-01
- Conservation genomics reveals low connectivity among populations of
threatened roseate terns (Sterna dougallii) in the Atlantic Basin-
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Abstract: While the effects of barriers to dispersal such as population declines, habitat fragmentation, and geographic distance have been well-documented in terrestrial wildlife, factors impeding the dispersal of highly vagile taxa such as seabirds are less well understood. The roseate tern (Sterna dougallii) is a globally distributed seabird species, but populations tend to be both fragmented and small, and the species is declining across most of its range. We evaluated structuring of roseate tern populations in the Northwestern Atlantic, the Caribbean, and the Azores using both microsatellite markers and single-nucleotide polymorphisms generated through targeted sequencing of Ultra-conserved Elements. For both marker types, we found significant genetic differentiation among all 3 populations and evidence for moderate contemporary unidirectional gene flow from the Caribbean to the Azores, but not between other populations. Within the Caribbean population, we found high rates of unidirectional migration from the Virgin Islands to Florida, potentially indicative of movement from source population to sink or an artifact of dispersal among other unsampled populations in the Caribbean region. These observations have significance for species persistence in the Atlantic, as our results indicate that loss of genetic diversity within populations is unlikely to be buffered by inflow of new alleles from other breeding populations.
PubDate: 2023-06-01
- A 37 K SNP array for the management and conservation of Golden Eagles
(Aquila chrysaetos)-
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Abstract: We describe the development of a custom 37 K Affymetrix Axiom myDesign single nucleotide polymorphism (SNP) array for a culturally and ecologically important apex predator, the golden eagle (Aquila chrysaetos). Using this SNP array, we performed population genomic analysis on 154 individuals of known natal localities and detected three genetic clusters that we designated as Taiga/High Arctic, Great Basin, and Rocky Mountains/Great Plains. Each of these clusters appears to display clinal variation within these geographic regions. After determining genetic structure, we performed an assignment test of 32 individuals, five of which were siblings of individuals used in the assessment of genetic structure, three had associated telemetry data, and the remaining individuals were of unknown natal locations. Using this array, four siblings were correctly assigned to the same geographic region as their sibling and the genetic assignment of the radio telemetered birds agreed with the expected movement patterns displayed by these individuals. For the remaining individuals, we were able to assign all but five individuals to one of the three genetic clusters. Our genetic assignments illustrates the utility of this SNP array to accurately assign most individuals to predesignated geographical regions. While further compiling genetic and other data types, we can increase the power of this tool for identifying those breeding populations that may need assistance due to anthropogenic stressors that negatively impact their population viability. The use of this genetic resource will help substantiate decisions by multiple conservation groups that seek to preserve the natural population structure of the golden eagle.
PubDate: 2023-06-01
- Genome-wide assessment of population genetic and demographic history in
Magnolia odoratissima based on SLAF-seq-
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Abstract: Magnolia odoratissima is a highly threatened species, with small distribution and scattered populations due to habitat fragmentation and human activity. In this study, the genetic diversity and population structure of the five remaining natural populations and two cultivated populations of M. odoratissima were analyzed using single nucleotide polymorphisms (SNPs) derived from specific-locus amplified fragment sequencing. A total of 180,650 SNPs were identified in seventy M. odoratissima individuals. The Nei’s and Shannon-Wiener diversity index across all M. odoratissima population were 0.35 and 0.51, respectively, while the observed heterozygosity (Ho) and expected heterozygosity (He) were 0.27 and 0.34, respectively. Our results suggest that M. odoratissima has relatively high genetic diversity at the genomic level. The FST and AMOVA indicated that high genetic differentiation exists among populations, and a phylogenetic neighbor-joining tree, Bayesian model–based clustering and discriminant function analysis of principal component all divided the M. odoratissima individuals into three distinct clusters. The Treemix analysis showed that there was low gene flow among the natural populations. Demographic history inferences indicated show that three clusters of M. odoratissima experienced at least three bottlenecks and resulted in a decrease of effective population size. Our results suggest that three distinct evolutionary significant units should be set up to conserve this critically endangered species.
PubDate: 2023-06-01
- Inferring inter-colony movement within metapopulations of yellow-footed
rock-wallabies using estimates of kinship-
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Abstract: Understanding the exchange of individuals between wildlife populations, particularly those with naturally fragmented habitats, is important for the effective management of these species. This is of particular consequence when the species is of conservation concern, and isolated populations may be lost due to pressures from predation or competition, or catastrophic events such as wildfire. Here we demonstrate the use kinship and population structure analysis to show potential recent movement between colonies in metapopulations of yellow-footed rock-wallaby (Petrogale xanthopus Gray 1854) at two sites in the Grey Range of Queensland, and at four sites in the Gawler Ranges of South Australia. These colonies are also compared to a single colony from the Flinders Ranges, a connected landscape of rock-wallaby habitat. Using reduced representation next-generation sequencing, we acquired and filtered a set of ~ 17,000 single-nucleotide polymorphisms to examine population genetic variation, structure and relationships within populations, and also identify putative migrants. Initial STRUCTURE analysis re-confirmed each population should be considered separately. Tests of population genetic variation identify several colonies appearing to be experiencing genetic erosion, also with low calculated effective population sizes (Ne = 4.5–36.6). Pairwise comparisons of individual relatedness (relatedness coeffiecients; r) implied several contemporary movement events between colonies within both the Gawler and Grey Ranges (r > 0.125), which was then affirmed with tests for putative first generation migrants. These results are of particular note in South Australia, where threat abatement (management of key predators and competitors) may facilitate dispersion. Additionally, in Queensland, colonies are separated by anthropogenic barriers: predator exclusion fencing designed to exclude dingoes (Canis familiaris) from grazing land, which may hinder dispersal. This work highlights the usefulness of population genetics to inform management outcomes in wildlife, in this case, highlighting the need for threatened species management at the landscape level.
PubDate: 2023-06-01
- Examining the spatiotemporal variation of genetic diversity and genetic
rarity in the natural plant recolonization of human-altered areas-
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Abstract: The spatiotemporal genetic variation at early plant life stages may substantially affect the natural recolonization of human-altered areas, which is crucial to understand plant and habitat conservation. In animal-dispersed plants, dispersers’ behavior may critically drive the distribution of genetic variation. Here, we examine how genetic rarity is spatially and temporally structured in seedlings of a keystone pioneer palm (Chamaerops humilis) and how the variation of genetic rarity could ultimately affect plant recruitment. We intensively monitored the seed rain mediated by two medium-sized carnivores during two consecutive seasons in a Mediterranean human-altered area. We genotyped 143 out of 309 detected seedlings using 12 microsatellite markers. We found that seedlings emerging from carnivore-dispersed seeds showed moderate to high levels of genetic diversity and no evidence of inbreeding. We found inflated kinship among seedlings that emerged from seeds within a single carnivore fecal sample, but a dilution of such FSGS at larger spatial scales (e.g. latrine). Seedlings showed a significant genetic sub-structure and the sibling relationships varied depending on the spatial scale. Rare genotypes arrived slightly later throughout the dispersal season and tended to be spatially isolated. However, genetic rarity was not a significant predictor by itself which indicates that, at least, its influence on seedling survival was smaller than other spatiotemporal factors. Our results suggest strong C. humilis resilience to genetic bottlenecks due to human disturbances. We highlight the study of plant-animal interactions from a genetic perspective since it provides crucial information for plant conservation and the recovery of genetic plant resilience.
PubDate: 2023-06-01
- Genomic evidence for three distinct species in the Erebia manto complex in
Central Europe (Lepidoptera, Nymphalidae)-
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Abstract: A problem to implement conservation strategies is that in many cases recognized taxa are in fact complexes of several cryptic species. Failure to properly delineate species may lead to misplaced priorities or to inadequate conservation measures. One such species complex is the yellow-spotted ringlet Erebia manto, which comprises several phenotypically distinct lineages, whose degree of genomic isolation has so far not been assessed. Some of these lineages are geographically restricted and thus possibly represent distinct units with conservation priorities. Using several thousand nuclear genomic markers, we evaluated to which degree the bubastis lineage from the Alps and the vogesiaca lineage from the Vosges, are genetically isolated from the widespread manto lineage. Our results suggest that both lineages are genetically as strongly differentiated from manto as other taxonomically well separated sibling species in this genus from each other, supporting a delineation of bubastis and vogesiaca as independent species. Given the restricted and isolated range of vogesiaca as well as the disjunct distribution of bubastis, our findings have significant implication for future conservation efforts on these formerly cryptic species and highlight the need to investigate the genomic identity within species complexes.
PubDate: 2023-06-01
- Fine-scale functional connectivity of two syntopic pond-breeding
amphibians with contrasting life-history traits: an integrative assessment
of direct and indirect estimates of dispersal-
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Abstract: Assessing patterns of functional connectivity among amphibian demes is crucial to unravel their population dynamics and prevent their isolation and eventual extinction. Integrative studies based on direct (capture-mark-recapture) and indirect (genetic) estimates of dispersal provide robust, biologically realistic inferences on population structure and connectivity, with applications for conservation efforts. We focused on two pond-breeding amphibians with contrasting life-history traits: the short-lived, semi-arboreal Hyla molleri and the long-lived, fossorial Pelobates cultripes. We PIT-tagged 2150 individuals of both species in two ponds (Laguna and Gravera, separated by 700 m) and monitored them from 2009 to 2021 to document the frequency and spatial extent of dispersal events. In addition, we genotyped individuals from these and two additional breeding populations at a maximum distance of 5 km with 15–16 microsatellites to characterize fine-scale patterns of genetic structure. We detected dispersal events connecting Laguna and Gravera in both species, albeit at low frequencies (4.8% and 7.7% of recaptured individuals of H. molleri and P. cultripes, respectively). However, both species were capable of covering long distances, with individual accumulated displacements up to 3.5 km (Hyla) and 1.8 km (Pelobates). Breeding populations > 2 km apart were genetically differentiated, indicating lower connectivity at this spatial scale. Estimates of pairwise migration rates differed between species and were asymmetrical, with different ponds representing “source” populations contributing more migrants to other populations in each species. We discuss the role of differences in life history traits and ecological preferences in shaping population dynamics in the two species and highlight management implications of our results.
PubDate: 2023-06-01
- Pooled whole genome sequencing of the endangered Banff Springs Snail,
Physella johnsoni, reveals genetic separation to P. gyrina and cryptic
micro-geographical genetic structure-
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Abstract: Determining cryptic species and diversity in at-risk species is necessary for the understanding and conservation of biodiversity. The endangered Banff Springs Snail, Physella johnsoni, inhabits seven highly specialized thermal springs in Banff National Park, Alberta, Canada. However, it has been difficult to reconcile its species status to the much more common Physella gyrina using ecology, morphology and genetics. Here we used pooled whole-genome sequencing to characterize genomic variation and structure among five populations of P. johnsoni and three geographical proximate P. gyrina populations. By comparing over two million single nucleotide polymorphisms, we detected substantial genetic distance (pairwise FST of 0.27 to 0.44) between P. johnsoni and P. gyrina, indicative of unique gene pools. Genetic clusters among populations were found for both species, with up to 10% for P. johnsoni and 30% for P. gyrina of genetic variation being explained by population structure. P. johnsoni was found to have lower genetic diversity compared to P. gyrina, however, no patterns of were observed between genetic diversity and population minimums. Our results confirm that designation of P. johnsoni as an endangered species is warranted and that both P. johnsoni and P. gyrina exhibit microgeographic population genomic structure suggestive of rapid local adaptation and/or genetic drift within environments. This study showcases the utility of genomics to resolve patterns of cryptic species and diversity for effective conservation management. Future studies on the functional genomic diversity of P. johnsoni populations are needed to test for the possible role of selection within this thermal spring environment.
PubDate: 2023-05-31
- Landscape genetics of the protected Spanish Moon Moth in core, buffer, and
peripheral areas of the Ordesa y Monte Perdido National Park (Central
Pyrenees, Spain)-
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Abstract: Conservation managers need to know the degree of connectivity showed by the populations to be preserved, especially when protected areas and/or species are involved. One of the conservation projects carried out by the Ordesa y Monte Perdido National Park (Central Pyrenees, Spain) is the monitoring of the protected Spanish Moon Moth, Graellsia isabellae (Lepidoptera, Saturniidae), in several sites within the actual park, buffer zone, and peripheral area. Here we studied the genetic diversity, geographical structure, and connectivity of this iconic insect in those areas with the aim of producing evidence-based recommendations that might help the National Park staff in their decision-making. For this, we non-lethally sampled 402 adult moths from 17 sites and worked at two geographic scales: Western/Central Pyrenees and the area monitored by the staff of the National Park. The multilocus genotypes obtained for nine nuclear microsatellite markers allowed us to quantify genetic variation, investigate population structure, and calculate recent migration rates. Our results revealed a large-scale (ca. 125 km) west–east cline in allele frequencies that causes low overall genetic differentiation (FST = 0.038) and similar levels of diversity among sites. Habitat connectivity revealed as an important element determining dispersal for G. isabellae, given the patchy distribution of the host plant (Pinus sylvestris) in the study area. Gene flow within and outside the National Park was proved, with a particular site of the buffer zone (Bujaruelo) acting as a source of migrants to other localities within and outside the National Park. This finding underlines the importance of considering buffer zones to preserve genetic diversity within protected areas, and that safeguarding the connectedness of pine patches is key to the conservation of this iconic moth.
PubDate: 2023-05-31
- Genomic and morphological assessment of the status of Kuenzler’s
hedgehog cactus (Echinocereus fendleri var. kuenzleri)-
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Abstract: Fendler’s hedgehog cactus (Echinocereus fendleri) is a morphologically variable species distributed across four U.S. states (AZ, CO, NM, TX) and the Mexican states of Sonora and Chihuahua. Some authors recognize a single, variable species, while others recognize up to four intraspecific taxa. This uncertainty carries conservation implications for E. fendleri var. kuenzleri (Kuenzler’s hedgehog cactus), which is listed as Federally threatened. The goal of the study was to examine genomic and morphological variation in Echinocereus fendleri to determine relationships among the three varieties primarily distributed in the United States, specifically focusing on the status of Kuenzler’s hedgehog cactus. Analyses of a double-digest restriction site-associated DNA sequence (ddRADseq) dataset indicated a well-supported E. fendleri clade. Within this clade, populations of E. fendleri var. rectispinus form a paraphyletic grade, with some sister to a well-supported clade containing all E. fendleri var. fendleri and E. fendleri var. kuenzleri. Three subclades are apparent within the E. fendleri var. fendleri/kuenzleri clade- a northern clade comprising E. fendleri var. fendleri, a central clade comprising E. fendleri var. fendleri and E. fendleri var. kuenzleri from Lincoln Co., NM, and a southeastern clade comprising two populations of E. fendleri var. kuenzleri. Trivariate analyses of morphological data establish three relatively distinct clusters of populations that correspond to the three focal varieties. These results establish that although each E. fendleri variety is morphologically distinct, none of them correspond to a single evolutionary lineage. The approach to conservation of E. fendleri var. kuenzleri should be re-evaluated, and three alternatives are discussed.
PubDate: 2023-05-30
- Genetic diversity and origin of captive lion (Panthera leo) in South
Africa: an assessment and comparison to wild populations-
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Abstract: South Africa has a large captive lion (Panthera leo) sector, but detailed knowledge on the origin of individuals and any potential genetic value to conservation targets is lacking. In 2021, the South African government committed to closing the sector and have since appointed a Ministerial Lion Task Team (2022) to initiate this process. Some have suggested that captive lions could be integrated into wild populations as part of the process but information on the genetic origins and diversity of captive lions is critical if this is to be explored further. Both the Biodiversity Management Plan for lions in South Africa (2015) and a High-Level Ministerial report for the South African government (2021) have called for more information on the genetic composition of captive lions. To determine the probable origin of captive lions in South Africa we summarised existing survey responses from captive facilities (collected 2017–2018) and CITES permit data (issued 1991–2019). Survey data suggest that most lions were sourced from within the South African captive sector. However, many CITES permits were also issued for the import of lions from across Africa and beyond, indicating possible mixed origins within the sector. To evaluate genetic relationships between captive and wild lions in South Africa we standardised existing microsatellite marker data from three laboratories and analysed genotypes of captive lions from 31 properties. A comparison of captive and wild lion genotypes revealed that the genetic composition of captive lions is currently comparable to existing wild South African lions. Captive lions cluster with similar probabilities to three of four regional reference populations of wild lions included in the study and no major signatures of inbreeding were identified. However, captive lions are highly genetically interconnected across properties and represent a smaller effective population size compared to Kruger National Park, the largest population of wild lions in South Africa, suggesting some risk of future inbreeding. There were also signatures of genetic drift which should be investigated further as it will likely compromise any potential conservation genetic value of captive lions in the future. The findings of this study should be considered when planning the fate of individuals within South Africa’s captive lion sector and within the broader context of African lion conservation.
PubDate: 2023-05-29
- Diversity and structure of Bettongia tropica: using population genetics to
guide reintroduction and help prevent the extinction of an endangered
Australian marsupial-
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Abstract: Conservation translocations can restore populations and prevent extinction of threatened species. Sourcing adequate genetic diversity is an essential consideration when planning reintroductions, because it influences individual fitness and long-term persistence of populations, yet available populations of threatened species may lack diversity. We estimated population genetic parameters for one of Australia’s most threatened mammals, the northern bettong, Bettongia tropica, to select source populations for reintroduction. Individuals from sites across the species’ extant range in the Wet Tropics of north Queensland were genotyped, using 6,133 informative SNPs. We found that samples clustered into four populations: an isolated northern population at Mt Spurgeon and three connected southern populations in the Lamb Range. Most of the species’ genetic diversity was dispersed across the Lamb Range populations in approximately equal proportions. Populations showed an isolation-by-distance effect, even over short distances within continuous habitat. Admixture of populations was high at distances < 7 km but low at distances > 11 km, and there was asymmetrical gene flow between the two closest neighboring populations. All populations had small effective sizes and experienced drift, but connectivity appears to have mitigated drift and stabilized population sizes within the Lamb Range. The Mt Spurgeon population had a very small effective population size and low genetic diversity. We use our findings to weigh up the risks and benefits of mixing sources for reintroduction, and we recommend a mixed source approach. We do not currently recommend sourcing individuals from Mt Spurgeon and conservation efforts to preserve this population are urgently required.
PubDate: 2023-05-29
- Landscape genetics in a highly threatened environment: how relevant to
ants is the physiognomic mosaic of the cerrado savanna'-
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Abstract: The Brazilian cerrado is one of the world’s biodiversity hotspots, comprising a mosaic of vegetation physiognomies. The cerrado presents a high ant diversity, and ant genetic variation can be subjected to the influence of landscape features. Here, we investigate how the composition and configuration of a cerrado reserve (4500 ha) in SE Brazil influence dispersal and gene flow (through measures of genetic distance) in two abundant carpenter ants, Camponotus renggeri and C. rufipes. Based on landscape genetics, we evaluated the degree of permeability of different land covers on the dispersal of ant queens, males and workers, employing a genetic optimization algorithm framework. We found little genetic structure in C. renggeri, regardless of caste. By contrast, we observed the formation of clear genetic clusters in C. rufipes, mainly for workers and queens. For workers of both species, we found that genetic distance was not influenced by geographic distance or landscape composition. For queens and males of C. renggeri, geographic distance was the most important factor explaining genetic distance. For C. rufipes queens and males, however, the best model considered the effect of landscape resistance to gene flow (i.e. the cost imposed by land use and cover types), with males dispersing through human-affected areas such as roads, and queens through forested cerrado areas. Our results showed that cerrado landscape can differentially affect ant dispersal, even for closely related species, reinforcing the importance of using different castes and sexes in landscape genetics of social insects. Our study also highlights that preservation of different vegetation physiognomies of cerrado is relevant for ant dispersal performance.
PubDate: 2023-05-27
- Genetic structure and north-south decrease of genetic diversity in the
Patagonian maqui berry (Aristotelia chilensis [Molina] Stuntz):
implications for its conservation and use-
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Abstract: Maqui (Aristotelia chilensis) is a small tree endemic to Patagonia. It is currently being actively domesticated for its edible berries, which have high polyphenol content and anti-oxidant capability. However, little is known about its population structure and evolutionary history, information which is useful for the design of effective conservation and domestication strategies. Based on information from other species, we hypothesize that genetic diversity in maqui is higher in northern population and decrease to the South, associated with past migration patterns and as a result has well-structured populations. To explore the genetic diversity of 14 populations (183 samples) of this species, that represent the geographic distribution of the species in Chile we used 13 polymorphic microsatellite markers. Clusters based on Bayesian genetic and spatial structure analyses were used to reconstruct patterns of phylogeographic and demographic history. We found that maqui populations are well-structured, with a substantial reduction of genetic diversity from north to south. The lowest diversity was found in areas that were once covered by ice during the quaternary glaciation. In conclusion, three main genetic groups were revealed by Structure analysis, and genetic diversity reduction from its northern limit in central Chile to the Patagonian region was found, suggesting that an active recolonization process took place during the last few millennia following the last glacial period. These results will help to define accessions from different regions and contribute to support conservation and domestication initiatives.
PubDate: 2023-05-27
- Large effective size as determinant of population persistence in Anostraca
(Crustacea: Branchiopoda)-
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Abstract: The fairy shrimp Branchinectella media, because of its passive dispersal capacity and scarce and irregularly distributed habitats (temporary saline aquatic systems), is an intriguing organism from a population genomics and conservation perspective. Stochasticity of dispersal events and the irregular distribution of its habitat might lead to low levels of population connectivity and genetic diversity, and consequently, populations with limited persistence through time. Indeed, by using genomic data (SNPs), we found a strong genetic structure among some of the geographically isolated Iberian populations of B. media. Interestingly, we also obtained high estimates of effective population sizes. Lack of suitable habitat between populations (absence of a “stepping stone” network) and strong genetic differentiation suggest limited dispersal success in B. media. However, the high effective population sizes observed ensure persistence of B. media populations against genetic stochasticity (genetic drift). These results indicate that rescue-effect might not be essential for population persistence if they maintain high effective population sizes able to hold adequate levels of genetic diversity. Should high population sizes be reported in other low dispersing Anostraca, one might be optimistic with regard to their conservation status and fate, provided that their natural habitats remain undisturbed.
PubDate: 2023-05-26
- Unexpected and spatially structured genetic diversity of the relict
population of the endangered corsican land snail Tyrrhenaria ceratina-
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Abstract: Population genetics of threatened species provides information about evolutionary pressures over those populations and thus may inform conservation management strategies. However, conservation genetics still has a low impact on conservation practices. This study’s aim is to integrate genetics in the conservation management of the only-known population of an extremely narrow-range endemic Corsican snail – Tyrrhenaria ceratina –, whose distribution area is restricted to the Ricantu site in Corsica. Using non-invasive DNA samples of 210 individuals, we amplified 13 microsatellites loci to assess the population viability, genetic structure and demographic history of the population, along with the estimation of the historical and contemporary gene flow between identified genetic clusters. We also estimated the dispersal ability of the species. Our results showed a surprisingly high genetic diversity, along with a pattern of isolation by distance (IBD) and a strongly spatialized genetic structure. Furthermore, we underlined a low functional connectivity, along with evidence of a recent decline in the population size, which are both likely due to a historical fragmentation between the sampled areas, caused by anthropization. Overall, this study allows to provide a first insight about the functioning of the population, to guide future conservation actions for the species.
PubDate: 2023-05-22
- Population genetics and phylogeography of Paramisgurnus dabryanus
(Cypriniformes: Cobitidae) in six river basins of China-
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Abstract: The present study aimed to investigate the population genetics of Paramisgurnus dabryanus across six river basins in China. Two mitochondrial genes (Cytochrome b and control region) and 12 microsatellite markers were employed to analyze the population genetics of 370 and 994 individuals, respectively, collected from 37 geographic locations. The analyses of both mitochondrial and microsatellite DNA revealed high levels of genetic diversity in P. dabryanus populations across the six river basins. Interestingly, the northern populations (Songliao River, Haihe River, and Yellow River) showed lower levels of genetic diversity compared to the southern populations (Huaihe River, Yangtze River, and Pearl River). Furthermore, the genetic analysis based on mitochondrial genes revealed no clear boundary between populations from different river basins, indicating no bottlenecks of gene flow among populations. Microsatellite analysis, on the other hand, revealed significant genetic differentiation between northern and southern populations, suggesting the need of two management units for P. dabryanus. Demographic analysis indicated that the Yangtze River populations have probably experienced population bottlenecks in the past, but also experienced a population expansion during the Last Glacial Maximum (LGM) when the warm climate was suitable for Yangtze River dispersal and survival after a recent genetic bottleneck. The integration of mitochondrial and microsatellite DNA data suggested that the Yangtze River populations are the most suitable population as a donor for the other river basins of P. dabryanus. Our findings have important implications for the conservation and effective management strategies of P. dabryanus.
PubDate: 2023-05-17
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