Biology subjects

Whiteley, A. R.

Publications and source records attributed to Whiteley, A. R..

3 recordsLinked to original sources

bioRxiv2024

The genome assembly of the westslope cutthroat trout, Oncorhynchus lewisi, reveals interspecific chromosomal rearrangements with the rainbow trout

Cutthroat trout (Oncorhynchus clarkii) are popular among anglers throughout their native range along the West Coast and interior of North America. As they colonized the interior of North America, cutthroat trout diverged into several genetically distinct groups. Many of these groups are now threatened by habitat destruction, hybridization with rainbow trout (O. mykiss), and competition from introduced species. These groups were previously classified as subspecies, but recent research suggests they may represent distinct species. In this study, we produced a chromosomal-level genome assembly and a genetic map for one of the species in the cutthroat trout species complex, the westslope cutthroat trout (O. lewisi--formerly O. clarki lewisi). We also constructed haplotype-resolved assemblies from a westslope cutthroat-rainbow trout F1 hybrid. We used the new genome assemblies to identify major interspecific chromosomal rearrangements between the two sister species, including fusions, fissions, and inversions. These genome assemblies and chromosome data provide valuable insights regarding genetic variation within cutthroat trout and in hybrids between rainbow and cutthroat trout. Article SummaryWestslope cutthroat trout inhabit bodies of water in several states and provinces near the Rocky Mountains and are well-known among anglers. In this study, we produced the first publicly available genome assemblies and a high-density genetic map for this species. These are research tools that allow detailed genetic analyses, including identifying differences among the genomes of related species. These comparisons allow researchers to understand the evolution of these species better and may provide insight into why successful interbreeding is possible among cutthroat and rainbow trout.

genomics↗

bioRxiv2023

Copy number variation and population-specific immune genes in the model vertebrate zebrafish

Many species have hundreds of immune genes from the NLR family (Nucleotide-binding domain Leucine-rich Repeat containing). In plants they have a considerable amount of within-species variation, but not much is known about their variability in fishes. Here we captured and analysed the diversity of NLRs in zebrafish (Danio rerio) by sequencing 93 individuals from four wild and two laboratory strains. We found 1,560 unique NLR genes, and theoretical modelling revealed each wild population to have around 2,000. Only 100-550 were detected in each individual fish, and the observed variance of copy numbers differed among populations. Laboratory strains were found to have three times less NLRs than wild populations, and their genetic diversity was lower in general. Many NLRs showed no single nucleotide variation, but those that did showed evidence of purifying selection. Our study lays the groundwork for unraveling mechanisms driving the evolution of this large gene family in vertebrates. Significance statementWe show here that the gene repertoires of vertebrates can be extremely variable, with different individuals having different genes. By sequencing one large family of immune receptors from 93 wild and laboratory zebrafish we found hundreds of novel gene copies, each only present in specific strains or specific individuals. Our observations can be explained by a combination of complex patterns of inheritance and a high rate of gene birth and death.

genetics↗

bioRxiv2019

The laboratory domestication of zebrafish: from diverse populations to inbred substrains

The zebrafish (Danio rerio) is a model vertebrate widely used to study disease, development and other aspects of vertebrate biology. Most of the research is performed on laboratory strains, one of which has been fully sequenced in order to derive a reference genome. It is known that the laboratory strains differ genetically from each other, but so far no genome-scale survey of variation between the laboratory and wild zebrafish populations exists.\n\nHere we use Restriction-Associated DNA sequencing (RAD-seq) to characterize three different wild zebrafish lineages from a population genetic viewpoint, and to compare them to four common laboratory strains. For this purpose we combine new genome-wide sequence data obtained from natural samples in India, Nepal and Bangladesh with a previously published dataset. We measured nucleotide diversity, heterozygosity, allele frequency spectra and patterns of gene conversion, and find that wild fish are much more diverse than laboratory strains. Further, in wild zebrafish there is a clear signal of GC-biased gene conversion that is missing in laboratory strains. We also find that zebrafish populations in Nepal and Bangladesh are distinct from all the other strains studied, making them an attractive subject for future studies of zebrafish population genetics and molecular ecology. Finally, isolates of the same strains kept in different laboratories show a clear pattern of ongoing differentiation into genetically distinct substrains. Together, our findings broaden the basis for future genetic and evolutionary studies in Danio rerio.

genetics↗