skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.


Title: Organellar DNA continues to provide a rich source of information in the genomics era
Abstract The genomics revolution continues to change how ecologists and evolutionary biologists study the evolution and maintenance of biodiversity. It is now easier than ever to generate large molecular data sets consisting of hundreds to thousands of independently evolving nuclear loci to estimate a suite of evolutionary and demographic parameters. However, any inferences will be incomplete or inaccurate if incorrect taxonomic identities and perpetuated throughout the analytical pipeline. Due to decades of research and comprehensive online databases, sequencing and analysis of mitochondrial DNA (mtDNA), chloroplast DNA (cpDNA) and select nuclear genes can provide researchers with a cost effective and simple means to verify the species identity of samples prior to subsequent phylogeographic and population genomic analysis. The addition of these sequences to genomic studies can also shed light on other important evolutionary questions such as explanations for gene tree‐species tree discordance, species limits, sex‐biased dispersal patterns, adaptation, and mtDNA introgression. Although the mtDNA and cpDNA genomes often should not be used exclusively to make historical inferences given their well‐known limitations, the addition of these data to modern genomic studies adds little cost and effort while simultaneously providing a wealth of useful data that can have significant implications for both basic and applied research.  more » « less
Award ID(s):
1929679
PAR ID:
10408603
Author(s) / Creator(s):
 
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Molecular Ecology
Volume:
32
Issue:
9
ISSN:
0962-1083
Page Range / eLocation ID:
p. 2144-2150
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Ruane, Sara (Ed.)
    Abstract Comparisons of intraspecific genetic diversity across species can reveal the roles of geography, ecology, and life history in shaping biodiversity. The wide availability of mitochondrial DNA (mtDNA) sequences in open-access databases makes this marker practical for conducting analyses across several species in a common framework, but patterns may not be representative of overall species diversity. Here, we gather new and existing mtDNA sequences and genome-wide nuclear data (genotyping-by-sequencing; GBS) for 30 North American squamate species sampled in the Southeastern and Southwestern United States. We estimated mtDNA nucleotide diversity for 2 mtDNA genes, COI (22 species alignments; average 16 sequences) and cytb (22 species; average 58 sequences), as well as nuclear heterozygosity and nucleotide diversity from GBS data for 118 individuals (30 species; 4 individuals and 6,820 to 44,309 loci per species). We showed that nuclear genomic diversity estimates were highly consistent across individuals for some species, while other species showed large differences depending on the locality sampled. Range size was positively correlated with both cytb diversity (phylogenetically independent contrasts: R2 = 0.31, P = 0.007) and GBS diversity (R2 = 0.21; P = 0.006), while other predictors differed across the top models for each dataset. Mitochondrial and nuclear diversity estimates were not correlated within species, although sampling differences in the data available made these datasets difficult to compare. Further study of mtDNA and nuclear diversity sampled across species’ ranges is needed to evaluate the roles of geography and life history in structuring diversity across a variety of taxonomic groups. 
    more » « less
  2. Kubatko, Laura (Ed.)
    Abstract Evidence from natural systems suggests that hybridization between animal species is more common than traditionally thought, but the overall contribution of introgression to standing genetic variation within species remains unclear for most animal systems. Here, we use targeted exon capture to sequence thousands of nuclear loci and complete mitochondrial genomes from closely related chipmunk species in the Tamias quadrivittatus group that are distributed across the Great Basin and the central and southern Rocky Mountains of North America. This recent radiation includes six overlapping, ecologically distinct species (Tamias canipes, Tamias cinereicollis, Tamias dorsalis, T. quadrivittatus, Tamias rufus, and Tamias umbrinus) that show evidence for widespread introgression across species boundaries. Such evidence has historically been derived from a handful of markers, typically focused on mitochondrial loci, to describe patterns of introgression; consequently, the extent of introgression of nuclear genes is less well characterized. We conducted a series of phylogenomic and species-tree analyses to resolve the phylogeny of six species in this group. In addition, we performed several population-genomic analyses to characterize nuclear genomes and infer coancestry among individuals. Furthermore, we used emerging quartets-based approaches to simultaneously infer the species tree (SVDquartets) and identify introgression (HyDe). We found that, in spite of rampant introgression of mitochondrial genomes between some species pairs (and sometimes involving up to three species), there appears to be little to no evidence for nuclear introgression. These findings mirror other genomic results where complete mitochondrial capture has occurred between chipmunk species in the absence of appreciable nuclear gene flow. The underlying causes of recurrent massive cytonuclear discordance remain unresolved in this group but mitochondrial DNA appears highly misleading of population histories as a whole. Collectively, it appears that chipmunk species boundaries are largely impermeable to nuclear gene flow and that hybridization, while pervasive with respect to mtDNA, has likely played a relatively minor role in the evolutionary history of this group. [Cytonuclear discordance; hyridization; introgression, phylogenomics; SVDquartets; Tamias.] 
    more » « less
  3. The flora and fauna of island systems, especially those in the Indo-Pacific, are renowned for their high diversification rates and outsized contribution to the development of evolutionary theories. The total diversity of geographic radiations of many Indo-Pacific fauna is often incompletely sampled in phylogenetic studies due to the difficulty in obtaining single island endemic forms across the Pacific and the relatively poor performance of degraded DNA when using museum specimens for inference of evolutionary relationships. New methods for production and analysis of genome-wide datasets sourced from degraded DNA are facilitating insights into the complex evolutionary histories of these influential island faunas. Here, we leverage whole genome resequencing (20X average coverage) and extensive sampling of all taxonomic diversity within Todiramphus kingfishers, a rapid radiation of largely island endemic Great Speciators. We find that whole genome datasets do not outright resolve the evolutionary relationships of this clade: four types of molecular markers (UCEs, BUSCOs, SNPs, and mtDNA) and tree building methods did not find a single well-supported and concordant species-level topology. We then uncover evidence of widespread incomplete lineage sorting and both ancient and contemporary gene flow and demonstrate how these factors contribute to conflicting evolutionary histories. Our complete taxonomic sampling allowed us to further identify a novel case of mitochondrial capture between two allopatric species, suggesting a potential historical (but since lost) hybrid zone as islands were successively colonized. Taken together, these results highlight how increased genomic and taxon sampling can reveal complex evolutionary patterns in rapid island radiations. 
    more » « less
  4. The rich diversity of morphology and behavior displayed across primate species provides an informative context in which to study the impact of genomic diversity on fundamental biological processes. Analysis of that diversity provides insight into long-standing questions in evolutionary and conservation biology and is urgent given severe threats these species are facing. Here, we present high-coverage whole-genome data from 233 primate species representing 86% of genera and all 16 families. This dataset was used, together with fossil calibration, to create a nuclear DNA phylogeny and to reassess evolutionary divergence times among primate clades. We found within-species genetic diversity across families and geographic regions to be associated with climate and sociality, but not with extinction risk. Furthermore, mutation rates differ across species, potentially influenced by effective population sizes. Lastly, we identified extensive recurrence of missense mutations previously thought to be human specific. This study will open a wide range of research avenues for future primate genomic research. 
    more » « less
  5. Abstract Rapid species radiations present difficulties for phylogenetic reconstruction due to lack of phylogenetic information and processes such as deep coalescence/incomplete lineage sorting and hybridization. Phylogenomic data can overcome some of these difficulties. In this study, we use anchored hybrid enrichment (AHE) nuclear phylogenomic data and mitochondrial genomes recovered from AHE bycatch with several concatenated and coalescent approaches to reconstruct the poorly resolved radiation of the New Zealand cicada species in the generaKikihiaDugdale andMaoricicadaDugdale. Compared with previous studies using only three to five Sanger‐sequenced genes, we find increased resolution across our phylogenies, but several branches remain unresolved due to topological conflict among genes. Some nodes that are strongly supported by traditional support measures like bootstraps and posterior probabilities still show significant gene and site concordance conflict. In addition, we find strong mito‐nuclear discordance; likely the result of interspecific hybridization events in the evolutionary history ofKikihiaandMaoricicada. 
    more » « less