Publications by authors named "Warren Johnson"

Genetic rescue-an increase in population fitness following the introduction of new alleles-has been proven to ameliorate inbreeding depression in small, isolated populations, yet is rarely applied as a conservation tool. A lingering question regarding genetic rescue in wildlife conservation is how long beneficial effects persist in admixed populations. Using data collected over 40 years from 1192 endangered Florida panthers (Puma concolor coryi) across nine generations, we show that the experimental genetic rescue implemented in 1995-via the release of eight female pumas from Texas-alleviated morphological, genetic, and demographic correlates of inbreeding depression, subsequently preventing extirpation of the population.

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The increased availability of quality genomic data has greatly improved the scope and resolution of our understanding of the recent evolutionary history of wild species adapted to extreme environments and their susceptibility to anthropogenic impacts. The guanaco (Lama guanicoe), the largest wild ungulate in South America, is a good example. The guanaco is well adapted to a wide range of habitats, including the Sechura Desert, the high Andes Mountains to the north, and the extreme temperatures and conditions of Navarino Island to the south.

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The black-footed ferret (Mustela nigripes) narrowly avoided extinction to become an oft-cited example of the benefits of intensive management, research, and collaboration to save a species through ex situ conservation breeding and reintroduction into its former range. However, the species remains at risk due to possible inbreeding, disease susceptibility, and multiple fertility challenges. Here, we report the de novo genome assembly of a male black-footed ferret generated through a combination of linked-read sequencing, optical mapping, and Hi-C proximity ligation.

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Similar to other apex predator species, populations of mainland () and Sunda () clouded leopards are declining. Understanding their patterns of genetic variation can provide critical insights on past genetic erosion and a baseline for understanding their long-term conservation needs. As a step toward this goal, we present draft genome assemblies for the two clouded leopard species to quantify their phylogenetic divergence, genome-wide diversity, and historical population trends.

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The remarkable radiation of South American (SA) canids produced 10 extant species distributed across diverse habitats, including disparate forms such as the short-legged, hypercarnivorous bush dog and the long-legged, largely frugivorous maned wolf. Despite considerable research spanning nearly two centuries, many aspects of their evolutionary history remain unknown. Here, we analyzed 31 whole genomes encompassing all extant SA canid species to assess phylogenetic relationships, interspecific hybridization, historical demography, current genetic diversity, and the molecular bases of adaptations in the bush dog and maned wolf.

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Article Synopsis
  • High-quality reference genomes for non-model species can enhance our understanding of their genetics and evolution.
  • These genomes provide essential data that can inform conservation strategies, helping to protect biodiversity.
  • Improved genomic resources can also aid in identifying genetic vulnerabilities and resilience in species, guiding conservation efforts more effectively.
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Ecological differentiation among diverging species is an important component of the evolutionary process and can be investigated in rapid and recent radiations. Here, we use whole genome sequences of five species from the genus Leopardus, a recently diversified Neotropical lineage with species bearing distinctive morphological, ecological, and behavioral features, to investigate genome-wide diversity, comparative demographic history and signatures of positive selection. Our results show that divergent ecological strategies are reflected in genomic features, for example a generalist species shows historically larger effective population size and higher heterozygosity than habitat specialists.

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Incomplete lineage sorting (ILS) makes ancestral genetic polymorphisms persist during rapid speciation events, inducing incongruences between gene trees and species trees. ILS has complicated phylogenetic inference in many lineages, including hominids. However, we lack empirical evidence that ILS leads to incongruent phenotypic variation.

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A global international initiative, such as the Earth BioGenome Project (EBP), requires both agreement and coordination on standards to ensure that the collective effort generates rapid progress toward its goals. To this end, the EBP initiated five technical standards committees comprising volunteer members from the global genomics scientific community: Sample Collection and Processing, Sequencing and Assembly, Annotation, Analysis, and IT and Informatics. The current versions of the resulting standards documents are available on the EBP website, with the recognition that opportunities, technologies, and challenges may improve or change in the future, requiring flexibility for the EBP to meet its goals.

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Extensive livestock production and urbanization entail modifications of natural landscapes, including installation of fences, development of agriculture, urbanization of natural areas, and construction of roads and infrastructure that, together, impact native fauna. Here, we evaluate the diversity and genetic structure of endemic guanacos () of the Monte and Patagonian Steppe of central Argentina, which have been reduced and displaced by sheep ranching and other impacts of human activities. Analyses of genetic variation of microsatellite loci and d-loop revealed high levels of genetic variation and latitudinal segregation of mitochondrial haplotypes.

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Article Synopsis
  • Scientists need good reference genomes to study biology, diseases, and protect wildlife, but there are only a few for non-microbial species.
  • The Genome 10K (G10K) group worked for five years to improve the way they create these high-quality genomes and gathered information from 16 different animal species.
  • Their work showed that special long-read technology improves genome quality, fixed errors in old genome sequences, and discovered new things about genes and chromosomes, leading to a new project to create complete genomes for about 70,000 vertebrate species.
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  • Human activities are altering natural habitats, which increases the spread of pathogens like feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) between domestic cats and wild species such as the guigna in Chile.
  • A study analyzed blood and tissue samples from 102 guignas and 262 domestic cats, revealing that the prevalence of FeLV and FIV was similar in both species, and that guigna viruses are closely related to those found in domestic cats globally.
  • The research highlighted that fragmented landscapes with domestic cats were linked to guigna FeLV infection, though there were few signs of illness in the guignas, underscoring the impact of habitat changes on wildlife health.
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  • Homotherium was a large, extinct genus of scimitar-toothed cats with unique physical traits suited for hunting large Pleistocene mammals.
  • Genetic analyses indicate that Homotherium diverged from modern cats about 22.5 million years ago, showing no signs of interbreeding with current felids.
  • The study revealed high genetic diversity in Homotherium, suggesting it was potentially more abundant than indicated by the fossil record, and highlights its adaptations in vision, behavior, and hunting strategies.
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BACKGROUNDControl of the tuberculosis (TB) pandemic remains hindered in part by a lack of simple and accurate measures of treatment efficacy, as current gold standard markers rely on sputum-based assays that are slow and challenging to implement. However, previous work identified urinary N1, N12-diacetylspermine (DiAcSpm), neopterin, hydroxykynurenine, N-acetylhexosamine, ureidopropionic acid, sialic acid, and mass-to-charge ratio (m/z) 241.0903 as potential biomarkers of active pulmonary TB (ATB).

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Background: The aims of this study were (1) to compare the prevalence of myocardial diastolic dysfunction (DD) in antiretroviral therapy (ART)-naive people living with human immunodeficiency virus (PLWH) to human immunodeficiency virus (HIV)-uninfected adults in East Africa and (2) to determine the association between serum concentration of the cardiac biomarkers ST2 and DD.

Methods: In this cross-sectional study, we enrolled PLWH and uninfected adults at a referral HIV clinic in Mwanza, Tanzania. Standardized history, echocardiography, and serum were obtained.

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Lions are one of the world's most iconic megafauna, yet little is known about their temporal and spatial demographic history and population differentiation. We analyzed a genomic dataset of 20 specimens: two 30,000-y-old cave lions (), 12 historic lions () that lived between the 15th and 20th centuries outside the current geographic distribution of lions, and 6 present-day lions from Africa and India. We found that cave and modern lions shared an ancestor 500,000 y ago and that the 2 lineages likely did not hybridize following their divergence.

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A molecular genetic protocol for distinguishing pure and hybrid South American camelids was developed to provide strong, quantifiable, and unbiased species identification. We detail the application of the approach in the context of a criminal case in the Andes Mountains of central Chile where the defendants were alleged to have illegally hunted three wild guanacos (Lama guanicoe), as opposed to hybrid domestic llama (Lama glama)/wild guanaco crosses, which are unregulated. We describe a workflow that differentiates among wild, domestic and hybrid South American camelids (Lama versus Vicugna) based on mitochondrial cytochrome b genetic variation (to distinguish between Lama and Vicugna), and MC1R and exon 4 variation of the ASIP gene (to differentiate wild from domestic species).

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Pumas are the most widely distributed felid in the Western Hemisphere. Increasingly, however, human persecution and habitat loss are isolating puma populations. To explore the genomic consequences of this isolation, we assemble a draft puma genome and a geographically broad panel of resequenced individuals.

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Typical avian eyes are phenotypically engineered for photopic vision (daylight). In contrast, the highly derived eyes of the barn owl (Tyto alba) are adapted for scotopic vision (dim light). The dramatic modifications distinguishing barn owl eyes from other birds include: 1) shifts in frontal orientation to improve binocularity, 2) rod-dominated retina, and 3) enlarged corneas and lenses.

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Genome-wide assessment of genetic diversity has the potential to increase the ability to understand admixture, inbreeding, kinship and erosion of genetic diversity affecting both captive () and wild () populations of threatened species. The sable antelope (), native to the savannah woodlands of sub-Saharan Africa, is a species that is being managed in both public (zoo) and private (ranch) collections in the United States. Our objective was to develop whole genome sequence resources that will serve as a foundation for characterizing the genetic status of populations of sable antelope relative to populations in the wild.

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Researchers have assembled thousands of eukaryotic genomes using Illumina reads, but traditional mate-pair libraries cannot span all repetitive elements, resulting in highly fragmented assemblies. However, both chromosome conformation capture techniques, such as Hi-C and Dovetail Genomics Chicago libraries and long-read sequencing, such as Pacific Biosciences and Oxford Nanopore, help span and resolve repetitive regions and therefore improve genome assemblies. One important livestock species of arid regions that does not have a high-quality contiguous reference genome is the dromedary (Camelus dromedarius).

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The role of chromosome rearrangements in driving evolution has been a long-standing question of evolutionary biology. Here we focused on ruminants as a model to assess how rearrangements may have contributed to the evolution of gene regulation. Using reconstructed ancestral karyotypes of Cetartiodactyls, Ruminants, Pecorans, and Bovids, we traced patterns of gross chromosome changes.

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Background: Leprosy is a treatable infectious disease caused by Mycobacterium leprae. However, there is additional morbidity from leprosy-associated pathologic immune reactions, reversal reaction (RR) and erythema nodosum leprosum (ENL), which occur in 1 in 3 people with leprosy, even with effective treatment of M. leprae.

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