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At least 163 records · Page 9Linked to original sources
USGS2024

A metapopulation strategy to support long term conservation of genetic diversity in Department of the Interior bison

Once numbering in the tens of millions, plains bison ( Bison bison bison ) were nearly driven to extinction with only a few hundred individuals remaining by the late 19th century. Plains bison have since recovered to approximately 20,000 animals managed in conservation herds throughout North America, yet substantial challenges to their recovery remain. The Department of the Interior (DOI) is working with diverse partners to steward approximately 11,000 bison in 18 conservation herds across 12 states. Most herds exist in areas without native predators, and removals are required to keep herd sizes at or below carrying capacity. The loss of genetic diversity within bison, and the fact that most DOI herds are relatively small and isolated from each other with no opportunity for natural gene flow, raises concerns about maintaining genetic diversity over the long term. Connecting populations through gene flow (i.e., creating a metapopulation) can minimize loss of genetic diversity, both within and across populations. Management of DOI bison conservation herds has historically varied across bureaus and conservation units. Adopting a national perspective on bison conservation was identified as a priority in the 2008 Department of the Interior Bison Conservation Initiative (BCI). The concept of metapopulation management as a potential tool to maximize the conservation of genetic diversity among DOI herds was first described in this 2008 Initiative and was specifically encouraged in the 2010 DOI Bison Conservation Genetics Workshop report (Dratch and Gogan 2010). In the 2020 BCI, the DOI re-affirmed its commitment to conserving bison as native, North American wildlife. This document establishes a framework for a nationally coordinated strategy for bison managed by the DOI to support the genetic conservation goals outlined in the 2020 BCI. This is a decisionmaking framework that guides managers through the process of determining when and how to consider translocations. Decisions and actions within the framework are informed by analysis and interpretation of data housed in an integrated, relational database that will be initially populated with the most current data and updated annually thereafter. It provides science-based guidance on how to conserve DOI bison genetic diversity through strategic translocations, while also considering cattle introgression and bison health. We illustrate how this Strategy can be used to guide the establishment of new conservation herds and discuss what it means to be a DOI partner. Finally, this is intended to be used as a living document that will evolve as needs and technologies change.

Science Report↗
USGS2021

Central-West Siberian-breeding Bar-tailed Godwits (Limosa lapponica) segregate in two morphologically distinct flyway populations

Long-distance migratory species often include multiple breeding populations, with distinct migration routes, wintering areas and annual-cycle timing. Detailed knowledge on population structure and migratory connectivity provides the basis for studies on the evolution of migration strategies and for species conservation. Currently, five subspecies of Bar-tailed Godwits Limosa lapponica have been described. However, with two apparently separate breeding and wintering areas, the taxonomic status of the subspecies L. l . taymyrensis remains unclear. Here we compare taymyrensis Bar-tailed Godwits wintering in the Middle East and West Africa, respectively, with respect to migration behaviour, breeding area, morphology and population genetic differentation in mitochondrial DNA. By tracking 52 individuals from wintering and staging areas over multiple years, we show that Bar-tailed Godwits wintering in the Middle East bred on the northern West-Siberian Plain ( n = 19), whilst birds from West Africa bred further east, mostly on the Taimyr Peninsula ( n = 12). The two groups differed significantly in body size and shape, and also in the timing of both northward and southward migrations. However, they were not genetically differentiated, indicating that the phenotypic (i.e. geographic, morphological and phenological) differences arose either very recently or without current reproductive isolation. We conclude that the taymyrensis taxon consists of two distinct populations with mostly non-overlapping flyways, which warrant treatment as separate taxonomic units. We thus propose to distinguish a more narrowly defined taymyrensis subspecies (i.e. the Bar-tailed Godwits wintering in West Africa and breeding on Taimyr), from a new yamalensis subspecies (i.e. the birds wintering in the Middle East and breeding on the northern West-Siberian Plain).

Ibis↗
USGS2026

Mountain goat declines in a protected, interior, native population

A shifting climate poses threats to alpine-adapted species including mountain goats. We used long-term (12 years) citizen science monitoring data and Bayesian N-mixture modeling to estimate population trends and drivers of population metrics among mountain goats in Glacier National Park (GNP). Median goats per site ( n = 37 sites) declined by 45% (95% credible interval [CRI] = 32%, 57%) from 77.8 (95% CRI = 64.4, 95.1) in 2008 to 42.3 (95% CRI = 34.3, 52.2) in 2019, with consistent declines from 2008 until 2015, when the number of estimated goats stabilized. The decline exceeds IUCN criteria for classifying a population as vulnerable, >30% declines over only two generations. Across years, relatively few goats occupied northwestern GNP. Goat numbers declined the most at northeastern sites, trended toward decline in most southern sites, and increased at only two west-central sites. The proportion of permanent snow and glaciers, the presence of natural mineral licks, and habituation strongly increased the initial abundance of goats in the area. Weather variables had the greatest influence on population growth rates, particularly precipitation between May 15 and June 15 of the previous summer, the neonatal period. Lower growth occurred with less snow water equivalent and lower mean winter temperature, early summer temperature, and early summer precipitation. Projected reductions of permanent snow, increasing spring and summer temperatures, and insufficient and variable spring precipitation raise concerns for the future of native goats in this region. Our analyses reveal ways to improve detection rates of goats during surveys, which is important for optimizing the precision of estimates and the power to detect future trends. Detection increased with goat habituation, retention of observers with experience, use of binoculars, and conducting surveys at lower temperatures and earlier dates. Improving detection will be particularly important given the lower number of goats currently observed in the park. Research to estimate park-wide population size, evaluate genetic structure and diversity, assess changing habitat, human recreation levels and forage, and forward-project climate effects on persistence will be crucial to understanding the context of these results and conserving this iconic, metapopulation at the southern edge of the distribution of native mountain goats.

Montana↗
USGS2024

Survival and growth of larval Pallid Sturgeon are improved by a live diet

Objective Conservation propagation facilities in the upper basin of the Missouri River are currently experiencing inconsistent survival of first-feeding larval Pallid Sturgeon Scaphirhynchus albus among genetic families (i.e., distinct male–female pairings). The inconsistent survival can have unintended negative consequences for genetic representation of Pallid Sturgeon that are returned to the Missouri and Yellowstone rivers. We conducted a laboratory study designed to determine whether a live diet improves survival and growth of first-feeding larval Pallid Sturgeon. Methods First-feeding larval Pallid Sturgeon from three distinct genetic families were assigned to one of the following diets: live first instar brine shrimp ( Artemia franciscana ) nauplii, an Otohime dry diet, a 50–50% combination of Otohime and live first instar brine shrimp nauplii, or food restricted (no food). Mortality was evaluated at the end of each day and at the end of the trial (21 days after the onset of exogenous feeding), and individual weight (g) was measured at the end of the trial. Result Pallid Sturgeon larvae that received a live diet (either solely live first instar brine shrimp nauplii or the combined diet) experienced higher survival than larvae that were fed solely Otohime. Furthermore, there was statistical evidence that larvae receiving solely live first instar brine shrimp nauplii were heavier at 21 days postexogenous feeding than larvae that were fed either solely Otohime or the combined diet. Conclusion Our results suggest that a live diet can improve survival and growth of first-feeding larval Pallid Sturgeon at conservation propagation facilities.

North American Journal of Aquaculture↗
USGS2018

The Pleurobemini (Bivalvia: Unionida) revisited: Molecular species delineation using a mitochondrial DNA gene reveals multiple conspecifics and undescribed species

The Pleurobemini (Bivalvia: Unionida) represent approximately one-third of freshwater mussel diversity in North America. Species identification within this group is challenging due to morphological convergence and phenotypic plasticity. Accurate species identification, including characterisation of currently unrecognised taxa, is required to develop effective conservation strategies because many species in the group are imperiled. We examined 575 cox1 sequences from 110 currently recognised species (including 13 Fusconaia and 21 Pleurobema species) to understand phylogenetic relationships among pleurobemine species (mainly Fusconaia and Pleurobema ) and to delineate species boundaries. The results of phylogenetic analyses showed no geographic structure within widespread species and illustrated a close relationship between Elliptio lanceolata and Parvaspina collina . Constraint tests supported monophyly of the genera Fusconaia and Pleurobema , including the subgenus P . ( Sintoxia ). Furthermore, results revealed multiple conspecifics, including P. hanleyianum and P. troschelianum , P. chattanoogaense and P. decisum , P. clava and P. oviforme , P. rubrum and P. sintoxia , F. askewi and F. lananensis , and F. cerina and F. flava . Species delimitation analyses identified three currently unrecognised taxa (two in Fusconaia and one in Pleurobema ). Further investigation using additional genetic markers and other lines of evidence (e.g. morphology, life history, ecology) are necessary before any taxonomic changes are formalised.

Invertebrate Systematics↗
USGS2014

From hybrid swarms to swarms of hybrids

Science has shown that the introgression or hybridization of modern humans ( Homo sapiens ) with Neanderthals up to 40,000 YBP may have led to the swarm of modern humans on earth. However, there is little doubt that modern trade and transportation in support of the humans has continued to introduce additional species, genotypes, and hybrids to every country on the globe. We assessed the utility of species distributions modeling of genotypes to assess the risk of current and future invaders. We evaluated 93 locations of the genus Tamarix for which genetic data were available. Maxent models of habitat suitability showed that the hybrid, T. ramosissima x T. chinensis , was slightly greater than the parent taxa (AUCs > 0.83). General linear models of Africanized honey bees, a hybrid cross of Tanzanian Apis mellifera scutellata and a variety of European honey bee including A. m. ligustica , showed that the Africanized bees (AUC = 0.81) may be displacing European honey bees (AUC > 0.76) over large areas of the southwestern U.S. More important, Maxent modeling of sub-populations (A1 and A26 mitotypes based on mDNA) could be accurately modeled (AUC > 0.9), and they responded differently to environmental drivers. This suggests that rapid evolutionary change may be underway in the Africanized bees, allowing the bees to spread into new areas and extending their total range. Protecting native species and ecosystems may benefit from risk maps of harmful invasive species, hybrids, and genotypes.

Environment and Ecology Research↗
USGS2017

Environmental Escherichia coli : Ecology and public health implications - A review

Escherichia coli is classified as a rod-shaped, Gram-negative bacterium in the family Enterobacteriaceae . The bacterium mainly inhabits the lower intestinal tract of warm-blooded animals, including humans, and is often discharged into the environment through feces or wastewater effluent. The presence of E. coli in environmental waters has long been considered as an indicator of recent fecal pollution. However, numerous recent studies have reported that some specific strains of E. coli can survive for long periods of time, and potentially reproduce, in extra-intestinal environments. This indicates that E. coli can be integrated into indigenous microbial communities in the environment. This naturalization phenomenon calls into question the reliability of E. coli as a fecal indicator bacterium (FIB). Recently, many studies reported that E. coli populations in the environment are affected by ambient environmental conditions affecting their long-term survival. Large-scale studies of population genetics provide the diversity and complexity of E. coli strains in various environments, affected by multiple environmental factors. This review examines the current knowledge on the ecology of E. coli strains in various environments in regards to its role as a FIB and as a naturalized member of indigenous microbial communities. Special emphasis is given on the growth of pathogenic E. coli in the environment, and the population genetics of environmental members of the genus Escherichia . The impact of environmental E. coli on water quality and public health is also discussed.

Journal of Applied Microbiology↗
USGS2018

Toward salt marsh harvest mouse recovery: A review

The salt marsh harvest mouse (SMHM, Reithrodontomys raviventris ) is an endangered species, endemic to the San Francisco Estuary. Despite being protected for almost half a century and being included in a large number of recovery, restoration, and management plans, significant data gaps hinder conservation and management of the species, a challenge further complicated by developing threats such as climate change. In this review, we present the current state of knowledge; highlight research gaps on habitat requirements and distribution, taxonomic status and genetic structure, physiology, reproduction and demographics, population dynamics, and behavior and community interactions; and present an overview of threats to the species. Our review indicates that substantial data gaps exist; although some aspects of SMHM ecology, such as habitat use, have been addressed extensively, others, such as the effects of environmental contamination, are largely unaddressed. We suggest that conservation and restoration-planning processes consider experimental approaches within restoration designs to address these deficiencies. Continued investment in basic and applied SMHM ecology to collect baseline and long-term data will also be beneficial. Additionally, further coordination among managers and researchers can facilitate more effective responses to uncertainties and emerging threats, especially climate change, which threatens the SMHM and its habitat throughout its range.

San Francisco Estuary and Watershed Science↗
USGS2013

Anatomical and genetic variation of western Oxyloma (Pulmonata: Succineidae) concerning the endangered Kanab ambersnail ( Oxyloma haydeni kanabense ) in Arizona and Utah

The land snail genus Oxyloma (Pulmonata: Succineidae) includes the Federally endangered Kanab ambersnail (Oxyloma haydeni kanabense Pilsbry), which is known at the time of this study from only two locations in the United States: Three Lakes, Utah, and Vaseys Paradise, Arizona, on the Colorado River in Grand Canyon National Park. Since 1994, the Kanab ambersnail has received much attention because its presence at Vaseys Paradise has implications for the ecosystem-wide management of the Colorado River. This attention is primarily because an experimental high-flow release of water from Glen Canyon Dam in 1996 destroyed or degraded Kanab ambersnail habitat at Vaseys Paradise. This experimental high flow was designed to replicate natural flow regimes throughout the Grand Canyon river corridor. However, as a result of the habitat destruction at Vaseys Paradise, in 1996, the U.S. Fish and Wildlife Service ruled that no further experimental high-discharge floods could be carried out until additional Kanab ambersnail populations were discovered or established. This mandate created a situation where the management of a single endangered species conflicted directly with the management of an entire ecosystem. Although since 1996, the U.S. Fish and Wildlife Service has permitted the use of flows as high as stage heights equivalent to 44,000 cubic feet per second, higher flows were requested by various Grand Canyon stakeholders and scientists but were not possible owing to low storage of Lake Powell. Adding to the controversy about Oxyloma and the Kanab ambersnail were previous anatomical and genetic analyses of the genus, which showed that genetic characteristics of specimens did not correspond with their identifications based on traditional taxonomic criteria, raising questions about the validity of the taxonomy of Oxyloma and the protected status of Kanab ambersnails. Specifically, a previous study suggested that the endangered Kanab ambersnail population at Three Lakes was more closely related to other, non-endangered ambersnail populations across the Southwest. In contrast, the Kanab ambersnail population at Vaseys Paradise appeared to be genetically distinct from all other ambersnail populations studied. Management options for the ambersnail population at Vaseys Paradise, at the time of this study, conflict with ecosystem-wide measures proposed to benefit other natural resources in the Grand Canyon. The U.S. Fish and Wildlife Service will not revise the 1995 Kanab Ambersnail Recovery Plan until further genetic and anatomical analyses provide more fine-scale taxonomic resolution of the identity of Oxyloma populations on the Colorado Plateau and elsewhere in the American Southwest. Likewise, interagency cooperators cannot revise down-listing criteria for the Kanab ambersnail until substantial evidence is provided identifying distinct Oxyloma taxa or a larger group of conspecifics that reasonably could be managed as one species. Therefore, given the current controversy about the taxonomy of Oxyloma and the endangered Kanab ambersnail, new detailed analyses were completed of morphological and genetic variation from many Oxyloma specimens collected at 12 western North American locations. These new data have allowed us to evaluate many issues related to Kanab ambersnail taxonomy. Using this dataset, the study of shells and anatomy indicates that the holotype of Oxyloma haydeni kanabense plausibly can be regarded as a member of the same species as the populations of Oxyloma analyzed in this study. Additionally, the presence of gene flow among all populations is evidence that they are members of the same species. Almost all the observed genetic diversity can be accounted for by short-distance or long-distance dispersal events between populations in this study. Our major taxonomic conclusion is that all samples collected for this study were drawn from populations of the same species.

Arizona;Utah↗
USGS2012

Genetic population substructure in bison at Yellowstone National Park

The Yellowstone National Park bison herd is 1 of only 2 populations known to have continually persisted on their current landscape since pre-Columbian times. Over the last century, the census size of this herd has fluctuated from around 100 individuals to over 3000 animals. Previous studies involving radiotelemetry, tooth wear, and parturition timing provide evidence of at least 2 distinct groups of bison within Yellowstone National Park. To better understand the biology of Yellowstone bison, we investigated the potential for limited gene flow across this population using multilocus Bayesian clustering analysis. Two genetically distinct and clearly defined subpopulations were identified based on both genotypic diversity and allelic distributions. Genetic cluster assignments were highly correlated with sampling locations for a subgroup of live capture individuals. Furthermore, a comparison of the cluster assignments to the 2 principle winter cull sites revealed critical differences in migration patterns across years. The 2 Yellowstone subpopulations display levels of differentiation that are only slightly less than that between populations which have been geographically and reproductively isolated for over 40 years. The identification of cryptic population subdivision and genetic differentiation of this magnitude highlights the importance of this biological phenomenon in the management of wildlife species.

Journal of Heredity↗
USGS2012

Divergence in morphology, but not habitat use, despite low genetic differentiation among insular populations of the lizard Anolis lemurinus in Honduras

Studies of recently isolated populations are useful because observed differences can often be attributed to current environmental variation. Two populations of the lizard Anolis lemurinus have been isolated on the islands of Cayo Menor and Cayo Mayor in the Cayos Cochinos Archipelago of Honduras for less than 15 000 y. We measured 12 morphometric and 10 habitat-use variables on 220 lizards across these islands in 2 y, 2008 and 2009. The goals of our study were (1) to explore patterns of sexual dimorphism, and (2) to test the hypothesis that differences in environment among islands may have driven divergence in morphology and habitat use despite genetic homogeneity among populations. Although we found no differences among sexes in habitat use, males had narrower pelvic girdles and longer toe pads on both islands. Between islands, males differed in morphology, but neither males nor females differed in habitat use. Our data suggest that either recent selection has operated differentially on males despite low genetic differentiation, or that they display phenotypic plasticity in response to environmental variation. We suggest that patterns may be driven by variation in intrapopulation density or differences in predator diversity among islands.

Journal of Tropical Ecology↗
USGS1987

Dispersal of three strains of hatchery-reared lake trout in Lake Ontario

Rates of dispersal and resultant geographical distributions were determined for three strains of hatchery-reared lake trout ( Salvelinus namaycush ) stocked at six sites in U.S. waters of Lake Ontario. The strains were Lake Superior (SUP); Clearwater Lake, Manitoba (CWL); and Seneca Lake, New York (SEN). The fish were recovered with bottom trawls fished during July and August 1980–1985 at 16 locations, extending from Toronto southward and eastward along the south shore to Dablon Point at the east end of the lake. For SUP fish stocked as spring yearlings, the mean distances from stocking site to capture location 2, 14, and 26 months after stocking were 12, 57, and 62 km, respectively, for fish released at four south-shore sites and 5, 34, and 38 km for fish released at two eastern outlet basin sites. Rates of dispersal for the CWL fish were similar to those of the SUP strain for fish stocked at the four south-shore sites, but were considerably less for fish stocked in the eastern outlet basin. The SEN strain was stocked only in the eastern outlet basin; their dispersal was similar to that of the SUP strain. For fish of the same age, SUP fish stocked as fall fingerlings became more widely dispersed than those stocked as spring yearlings. Movement of lake trout between the eastern outlet basin and the lake proper was limited. Large numbers of fish were captured on the Niagara Bar, but few moved past there into the west end of the lake. Movements of lake trout from stocking sites were generally with the prevailing currents. Differences between geographical distributions of the SUP and CWL strains were probably due to the influence of different current regimes at the depths they occupied. These results will be useful in selecting the best genetic strains of lake trout for rehabilitating the species in Lake Ontario, as well as for identifying the best stocking sizes and maximizing post-stocking survival of hatchery-reared fish.

Journal of Great Lakes Research↗
USGS2016

A new biogeographically disjunct giant gecko ( Gehyra : Gekkonidae: Reptilia) from the East Melanesian Islands

The East Melanesian Islands have been a focal area for research into island biogeography and community ecology. However, previously undescribed and biogeographically significant new species endemic to this region continue to be discovered. Here we describe a phylogenetically distinct (~20% divergence at the mitochondrial ND2 gene) and biogeographically disjunct new species of gecko in the genus Gehyra , from the Admiralty and St Matthias Islands. Gehyra rohan sp. nov. can be distinguished from all congeners by the combination of its very large size, ring of bright orange scales around the eye, moderate degree of lateral folding on the limbs and body, and aspects of head, body and tail scalation. Molecular data indicate mid to late Miocene divergence of the new species from nearest relatives occurring nearly 2000 kilometres away in Vanuatu and Fiji. Large Gehyra have not been recorded on the intervening large islands of the Bismark Archipelago (New Britain and New Ireland) and the Solomon Islands, suggesting this dispersal pre-dated the current configuration of these islands, extinction in intervening regions, or potentially elements of both. Conversely, low genetic divergence between disjunct samples on Manus and Mussau implies recent overseas dispersal via either natural or anthropogenic means.

Zootaxa↗
USGS2018

Stock structure, dynamics, demographics, and movements of walleyes spawning in four tributaries to Green Bay

To test assumptions related to the current conceptual model for walleye Sander vitreus management in Green Bay, we evaluated whether: 1) spawning aggregations in the Fox, Menominee, Oconto, and Peshtigo rivers represent genetically distinct stocks; 2) population dynamics and demographics vary among walleye spawning at these locations; 3) walleye spawning in these rivers contribute to the fishery in northern Green Bay, and 4) walleye spawning in these rivers exhibit spawning site fidelity or if they stray among rivers. Genetic differentiation among the four tributaries was low and sex-specific total length (TL), mean TL at age 5, and age-class diversity were generally similar among rivers and observed differences were not consistent. Movements of walleye inferred from angler tag returns suggest that walleye spawning (and tagged) in the four tributaries typically remain within southern Green Bay; however, this assertion may be confounded by the distribution of angling effort that provides tag recoveries. Straying rates among rivers ranged from 0 to 23% and were likely sufficient to preclude genetic differentiation among stocks. Collectively, results suggest that walleye spawning in the Fox, Menominee, Oconto, and Peshtigo rivers do not function as separate stocks and do not significantly contribute to the fishery outside of southern Green Bay. The primary assumption of the current conceptual model that remains to be tested is whether the walleye fishery in southern Green Bay is supported primarily by fish spawning in these four rivers, or if there are substantial contributions from fish spawning at other unknown locations.

Wisconsin↗
USGS2026

Genetic structure in a previously extirpated population of gray wolves following reintroduction and natural recolonization

Genetic structuring in wildlife populations is driven by barriers that restrict gene flow as well as the history of population demography. Mechanisms driving genetic structuring can be nuanced in group-living species, such as gray wolves ( Canis lupus ). Behavioral factors, such as social affiliation and resistance, natal habitat imprinting, and trade-offs between dispersal from natal packs and territorial biding, affect habitat selection of wolves despite landscape barriers providing little resistance to their extensive dispersal capabilities. Wolves were previously extirpated from Idaho, USA, and current populations are the result of both reintroductions in 1995 and 1996 and natural dispersal from Canada. In this context we examined genetic structure of wolves in Idaho using 101 individuals genotyped at 18 nuclear DNA microsatellite loci and a subset of 38 individuals genotyped at 1019 single nucleotide polymorphism markers. We hypothesized panmictic (i.e., random mating) genetic structure in Idaho due to the long-distance dispersal abilities of gray wolves. Contrary to our hypothesis, we found three genetic clusters of gray wolves in Idaho, primarily supported by SNP markers. Microsatellite data suggested similar patterns, but permutation tests indicated these differences were not statistically significant. The extent of differentiation and evidence of gene flow, however, suggests that the three genetic clusters are not wholly isolated from one another. The distinctions between clusters spatially align with areas of reintroduction into central Idaho and Yellowstone National Park, as well ongoing natural recolonization from adjacent populations in Canada and Montana. Wolves at the periphery of analysis areas showed more admixture than those in the core, consistent with territoriality and mating behaviors contributing to genetic structuring. We demonstrate how management history, including reintroduction efforts, and animal behavior may interact and contribute to patterns of genetic structure in wild populations.

Idaho, Montana, Wyoming↗
USGS2005

Genetic diversity, kinship analysis, and broodstock management of captive Atlantic sturgeon for population restoration

Captive Atlantic sturgeon Acipenser oxyrinchus considered for use as broodstock in a restoration program were genotyped using nuclear DNA microsatellites and compared to wild collections from the Hudson River, New York (source of parents of the captive sturgeon) and from Albemarle Sound, North Carolina. Because the potential broodfish were the progeny of a small number of parents, maintaining genetic diversity and minimizing inbreeding is essential to a successful breeding and supplementation program. The microsatellite loci used in this analysis generated unique multilocus genotypes for each of 136 Atlantic sturgeon. Analyses indicated significant genetic separation between the New York and North Carolina collections and correctly identified the potential broodstock as a subset of the Hudson River population. Pairwise genetic distance (-In proportion of shared alleles) between half and full siblings in the potential broodfish was as great as 1.386, a value exceeded by only 36% of the sampled broodfish pairs available for mating. Because the current broodstock population does not seem to have deviated far from their ancestral population in the Hudson River, progeny from that broodstock, or the parents themselves, would seem to be genetically suitable for release back into the Hudson River.

American Fisheries Society Symposium↗
USGS2026

Sedimentological and geochemical characterization of lacustrine deposits of the Babouri-Figuil basin, northern Cameroon: Implications for source rocks distribution and petroleum exploration

The West and Central African Rift System (WCARS) refers to the series of Cretaceous rift basins where commercial hydrocarbon accumulations have been discovered. Some of the WCARS frontier basins are currently being investigated to increase our understanding of these basins in light of new commercial discoveries. The present study was performed in the Babouri-Figuil Basin (BFB), which is genetically related to the WCARS and constitutes an area of interest in terms of petroleum prospecting, where the distribution of petroleum source rocks and potential targets for petroleum exploration across the entire basin is poorly understood. For the current study, an integrated facies analysis along with organic and inorganic geochemical techniques were applied to the basin's Cretaceous deposits with the aim of reconstructing the paleodepositional environment, assessing factors that triggered the input of organic matter, and providing a spatial overview of the organic matter accumulation in the basin based on outcrop samples. An alluvial fan-lacustrine-braided river system is inferred from the facies analysis of the stratigraphic sequence consisting of conglomerate, sandstone, siltstone, limestone, marlstone, and claystone. Bulk analysis of organic matter reveals that black shale and massive claystone are the main prospective petroleum source rocks in the basin. Inorganic geochemical analyses reveal the influence of anoxic conditions, moderate to high primary productivity, and low terrigenous inputs in organic matter enrichment. The formations rich in organic matter are predominantly concentrated in the western and eastern parts of the basin which may represent areas with depressions, characterized by high accommodation space. In terms of the regional context of the WCARS rift basins, typical hydrocarbon exploration in the BFB may target basal-conglomerate, sandstone beds situated directly above or/and interbedded with the Lower Cretaceous source rocks, and the Upper Cretaceous sandstone beds. Basement rocks (granite, granodiorite, and gneisses) and oil shale deposits may represent potential unconventional hydrocarbon exploration. The current integrated study provides an insight that should guide future hydrocarbon exploration campaigns in the basin.

Babouri-Figuil basin↗
USGS2019

Spatially-structured statistical network models for landscape genetics

A basic understanding of how the landscape impedes, or creates resistance to, the dispersal of organisms and hence gene flow is paramount for successful conservation science and management. Spatially structured ecological networks are often used to represent spatial landscape‐genetic relationships, where nodes represent individuals or populations and resistance to movement is represented using non‐binary edge weights. Weights are typically assigned or estimated by the user, rather than observed, and validating such weights is challenging. We provide a synthesis of current methods used to estimate edge weights and an overview of common model types, stressing the advantages and disadvantages of each approach and their ability to model landscape‐genetic data. We further explore a set of spatial‐statistical methods that provide ecologists with alternative approaches for modeling spatially explicit processes that may affect genetic structure. This includes an overview of spatial autoregressive models, with a particular focus on how correlation and partial correlation are used to represent neighborhood structure with the inverse of the covariance matrix (i.e., precision matrix). We then demonstrate how to model resistance by specifying an appropriate statistical model on the nodes, conditioned on the edge weights, through the precision matrix. This integration of network ecology and spatial statistics provides a practical analytical framework for landscape‐genetic studies. The results can be used to make statistical inferences about the relative importance of individual landscape characteristics, such as the vegetative cover, hillslope, or the presence of roads or rivers, on gene flow. In addition, the R code we include allows readers to explore landscape‐genetic structure in their own datasets, which will potentially provide new insights into the evolutionary processes that generated ecological networks, as well as valuable information about the optimal characteristics of conservation corridors.

Ecological Monographs↗