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Derkarabetian S, Starrett J, Hedin M. Using natural history to guide supervised machine learning for cryptic species delimitation with genetic data. Front Zool 2022; 19:8. [PMID: 35193622 PMCID: PMC8862334 DOI: 10.1186/s12983-022-00453-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/27/2022] [Indexed: 12/28/2022] Open
Abstract
The diversity of biological and ecological characteristics of organisms, and the underlying genetic patterns and processes of speciation, makes the development of universally applicable genetic species delimitation methods challenging. Many approaches, like those incorporating the multispecies coalescent, sometimes delimit populations and overestimate species numbers. This issue is exacerbated in taxa with inherently high population structure due to low dispersal ability, and in cryptic species resulting from nonecological speciation. These taxa present a conundrum when delimiting species: analyses rely heavily, if not entirely, on genetic data which over split species, while other lines of evidence lump. We showcase this conundrum in the harvester Theromaster brunneus, a low dispersal taxon with a wide geographic distribution and high potential for cryptic species. Integrating morphology, mitochondrial, and sub-genomic (double-digest RADSeq and ultraconserved elements) data, we find high discordance across analyses and data types in the number of inferred species, with further evidence that multispecies coalescent approaches over split. We demonstrate the power of a supervised machine learning approach in effectively delimiting cryptic species by creating a "custom" training data set derived from a well-studied lineage with similar biological characteristics as Theromaster. This novel approach uses known taxa with particular biological characteristics to inform unknown taxa with similar characteristics, using modern computational tools ideally suited for species delimitation. The approach also considers the natural history of organisms to make more biologically informed species delimitation decisions, and in principle is broadly applicable for taxa across the tree of life.
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Affiliation(s)
- Shahan Derkarabetian
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, 26 Oxford St., Cambridge, MA, 02138, USA.
| | - James Starrett
- Department of Entomology and Nematology, University of California, Davis, Briggs Hall, Davis, CA, 95616-5270, USA
| | - Marshal Hedin
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-4614, USA
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2
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Ortiz D, Pekár S, Dianat M. Phylogenomics and loci dropout patterns of deeply diverged Zodarion ant-eating spiders suggest a high potential of RAD-seq for genus-level spider phylogenetics. Cladistics 2021; 38:320-334. [PMID: 34699083 DOI: 10.1111/cla.12493] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2021] [Indexed: 11/28/2022] Open
Abstract
RAD sequencing yields large amounts of genome-wide data at a relatively low cost and without requiring previous taxon-specific information, making it ideal for evolutionary studies of highly diversified and neglected organisms. However, concerns about information decay with phylogenetic distance have discouraged its use for assessing supraspecific relationships. Here, using Double Digest Restriction Associated DNA (ddRAD) data, we perform the first deep-level approach to the phylogeny of Zodarion, a highly diversified spider genus. We explore the impact of loci and taxon filtering across concatenated and multispecies coalescent reconstruction methods and investigate the patterns of information dropout in reference to both the time of divergence and the mitochondrial divergence between taxa. We found that relaxed loci-filtering and nested taxon-filtering strategies maximized the amount of molecular information and improved phylogenetic inference. As expected, there was a clear pattern of allele dropout towards deeper time and mitochondrial divergences, but the phylogenetic signal remained strong throughout the phylogeny. Therefore, we inferred topologies that were almost fully resolved, highly supported, and noticeably congruent between setups and inference methods, which highlights overall inconsistency in the taxonomy of Zodarion. Because Zodarion appears to be among the oldest and most mitochondrially diversified spider genera, our results suggest that ddRAD data show high potential for inferring intra-generic relationships across spiders and probably also in other taxonomic groups.
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Affiliation(s)
- David Ortiz
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czechia
| | - Stano Pekár
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czechia
| | - Malahat Dianat
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czechia
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3
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Christiansen H, Heindler FM, Hellemans B, Jossart Q, Pasotti F, Robert H, Verheye M, Danis B, Kochzius M, Leliaert F, Moreau C, Patel T, Van de Putte AP, Vanreusel A, Volckaert FAM, Schön I. Facilitating population genomics of non-model organisms through optimized experimental design for reduced representation sequencing. BMC Genomics 2021; 22:625. [PMID: 34418978 PMCID: PMC8380342 DOI: 10.1186/s12864-021-07917-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/26/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Genome-wide data are invaluable to characterize differentiation and adaptation of natural populations. Reduced representation sequencing (RRS) subsamples a genome repeatedly across many individuals. However, RRS requires careful optimization and fine-tuning to deliver high marker density while being cost-efficient. The number of genomic fragments created through restriction enzyme digestion and the sequencing library setup must match to achieve sufficient sequencing coverage per locus. Here, we present a workflow based on published information and computational and experimental procedures to investigate and streamline the applicability of RRS. RESULTS In an iterative process genome size estimates, restriction enzymes and size selection windows were tested and scaled in six classes of Antarctic animals (Ostracoda, Malacostraca, Bivalvia, Asteroidea, Actinopterygii, Aves). Achieving high marker density would be expensive in amphipods, the malacostracan target taxon, due to the large genome size. We propose alternative approaches such as mitogenome or target capture sequencing for this group. Pilot libraries were sequenced for all other target taxa. Ostracods, bivalves, sea stars, and fish showed overall good coverage and marker numbers for downstream population genomic analyses. In contrast, the bird test library produced low coverage and few polymorphic loci, likely due to degraded DNA. CONCLUSIONS Prior testing and optimization are important to identify which groups are amenable for RRS and where alternative methods may currently offer better cost-benefit ratios. The steps outlined here are easy to follow for other non-model taxa with little genomic resources, thus stimulating efficient resource use for the many pressing research questions in molecular ecology.
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Affiliation(s)
- Henrik Christiansen
- Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium.
| | - Franz M Heindler
- Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium
| | - Bart Hellemans
- Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium
| | - Quentin Jossart
- Marine Biology Group, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | | | - Henri Robert
- OD Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Marie Verheye
- OD Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Bruno Danis
- Marine Biology Laboratory, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Marc Kochzius
- Marine Biology Group, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Frederik Leliaert
- Marine Biology Research Group, Ghent University, Ghent, Belgium.,Meise Botanic Garden, Meise, Belgium
| | - Camille Moreau
- Marine Biology Laboratory, Université Libre de Bruxelles (ULB), Brussels, Belgium.,Université de Bourgogne Franche-Comté (UBFC) UMR CNRS 6282 Biogéosciences, Dijon, France
| | - Tasnim Patel
- OD Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Anton P Van de Putte
- Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium.,OD Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium.,Marine Biology Laboratory, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Ann Vanreusel
- Marine Biology Research Group, Ghent University, Ghent, Belgium
| | - Filip A M Volckaert
- Laboratory of Biodiversity and Evolutionary Genomics, KU Leuven, Leuven, Belgium
| | - Isa Schön
- OD Nature, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
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4
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Double-digest RAD-sequencing: do pre- and post-sequencing protocol parameters impact biological results? Mol Genet Genomics 2021; 296:457-471. [PMID: 33469716 DOI: 10.1007/s00438-020-01756-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 12/14/2020] [Indexed: 02/06/2023]
Abstract
Next-generation sequencing technologies have opened a new era of research in population genetics. Following these new sequencing opportunities, the use of restriction enzyme-based genotyping techniques, such as restriction site-associated DNA sequencing (RAD-seq) or double-digest RAD-sequencing (ddRAD-seq), has dramatically increased in the last decade. From DNA sampling to SNP calling, the laboratory and bioinformatic parameters of enzyme-based techniques have been investigated in the literature. However, the impact of those parameters on downstream analyses and biological results remains less documented. In this study, we investigated the effects of sevral pre- and post-sequencing settings on ddRAD-seq results for two biological systems: a complex of butterfly species (Coenonympha sp.) and several populations of common beech (Fagus sylvatica). Our results suggest that pre-sequencing parameters (i.e., DNA quantity, number of PCR cycles during library preparation) have a significant impact on the number of recovered reads and SNPs, on the number of unique alleles and on individual heterozygosity. In the same way, we found that post-sequencing settings (i.e., clustering and minimum coverage thresholds) influenced loci reconstruction (e.g., number of loci, mean coverage) and SNP calling (e.g., number of SNPs; heterozygosity) but had only a marginal impact on downstream analyses (e.g., measure of genetic differentiation, estimation of individual admixture, and demographic inferences). In addition, replication analyses confirmed the reproducibility of the ddRAD-seq procedure. Overall, this study assesses the degree of sensitivity of ddRAD-seq data to pre- and post-sequencing protocols, and illustrates its robustness when studying population genetics.
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5
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Brown TA, Tsurusaki N, Burns M. Genomic Determination of Reproductive Mode in Facultatively Parthenogenetic Opiliones. J Hered 2021; 112:34-44. [PMID: 33448304 DOI: 10.1093/jhered/esaa045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 11/03/2020] [Indexed: 01/15/2023] Open
Abstract
Sexual reproduction may pose myriad short-term costs to females. Despite these costs, sexual reproduction is near ubiquitous. Facultative parthenogenesis is theorized to mitigate some of the costs of sex, as individuals can participate in occasional sex to limit costs while obtaining many benefits. However, most theoretical models assume sexual reproduction is fixed following mating, with no possibility of clutches of mixed reproductive ontogeny. Therefore, we asked: if coercive males are present at high frequency in a population of facultative parthenogens, will their clutches be solely sexually produced, or will there be evidence of sexually and asexually-produced offspring? How will their offspring production compare to conspecifics in low-frequency male populations? We addressed our questions by collecting females and egg clutches of the facultatively parthenogenetic Opiliones species Leiobunum manubriatum and L. globosum. In L. manubriatum, females from populations with few males were not significantly more fecund than females from populations with higher male relative frequency, despite the potential release of the former from sexual conflict. We used 3 genotyping methods along with a custom set of DNA capture probes to reveal that offspring of L. manubriatum from these high male populations were primarily produced via asexual reproduction. This is surprising because sex ratios in these southern populations approach equality, increasing the probability for females to encounter mates and produce offspring sexually. We additionally found evidence for reproductive polymorphisms within populations. Rapid and accurate SNP genotyping data will continue to allow us to address broader evolutionary questions regarding the role of facultative reproductive modes in the maintenance of sex.
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Affiliation(s)
- Tyler A Brown
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD
| | - Nobuo Tsurusaki
- Laboratory of Biodiversity and Taxonomy, Department of Agricultural, Life, and Environmental Sciences, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Mercedes Burns
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD
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6
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Newton LG, Starrett J, Hendrixson BE, Derkarabetian S, Bond JE. Integrative species delimitation reveals cryptic diversity in the southern Appalachian Antrodiaetus unicolor (Araneae: Antrodiaetidae) species complex. Mol Ecol 2020; 29:2269-2287. [PMID: 32452095 DOI: 10.1111/mec.15483] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 05/14/2020] [Accepted: 05/18/2020] [Indexed: 12/26/2022]
Abstract
Although species delimitation can be highly contentious, the development of reliable methods to accurately ascertain species boundaries is an imperative step in cataloguing and describing Earth's quickly disappearing biodiversity. Spider species delimitation remains largely based on morphological characters; however, many mygalomorph spider populations are morphologically indistinguishable from each other yet have considerable molecular divergence. The focus of our study, the Antrodiaetus unicolor species complex containing two sympatric species, exhibits this pattern of relative morphological stasis with considerable genetic divergence across its distribution. A past study using two molecular markers, COI and 28S, revealed that A. unicolor is paraphyletic with respect to A. microunicolor. To better investigate species boundaries in the complex, we implement the cohesion species concept and use multiple lines of evidence for testing genetic exchangeability and ecological interchangeability. Our integrative approach includes extensively sampling homologous loci across the genome using a RADseq approach (3RAD), assessing population structure across their geographic range using multiple genetic clustering analyses that include structure, principal components analysis and a recently developed unsupervised machine learning approach (Variational Autoencoder). We evaluate ecological similarity by using large-scale ecological data for niche-based distribution modelling. Based on our analyses, we conclude that this complex has at least one additional species as well as confirm species delimitations based on previous less comprehensive approaches. Our study demonstrates the efficacy of genomic-scale data for recognizing cryptic species, suggesting that species delimitation with one data type, whether one mitochondrial gene or morphology, may underestimate true species diversity in morphologically homogenous taxa with low vagility.
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Affiliation(s)
- Lacie G Newton
- Department of Entomology and Nematology, University of California, Davis, CA, USA
| | - James Starrett
- Department of Entomology and Nematology, University of California, Davis, CA, USA
| | | | - Shahan Derkarabetian
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA, USA
| | - Jason E Bond
- Department of Entomology and Nematology, University of California, Davis, CA, USA
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7
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Hedin M, Foldi S, Rajah-Boyer B. Evolutionary divergences mirror Pleistocene paleodrainages in a rapidly-evolving complex of oasis-dwelling jumping spiders (Salticidae, Habronattus tarsalis). Mol Phylogenet Evol 2020; 144:106696. [DOI: 10.1016/j.ympev.2019.106696] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/14/2019] [Accepted: 11/27/2019] [Indexed: 10/25/2022]
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8
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Postiglioni R, Bidegaray-Batista L, Simó M, Arnedo MA. Move to stay: genetic structure and demographic history of a wolf spider inhabiting coastal sand dunes of southern South America. SYST BIODIVERS 2019. [DOI: 10.1080/14772000.2019.1689197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Rodrigo Postiglioni
- Departamento de Ecología y Biología Evolutiva, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, Montevideo, CP 11600, Uruguay
- Sección Entomología. Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, CP 11400, Uruguay
| | - Leticia Bidegaray-Batista
- Departamento de Biodiversidad y Genética, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, Montevideo, CP 11600, Uruguay
| | - Miguel Simó
- Departamento de Ecología y Biología Evolutiva, Instituto de Investigaciones Biológicas Clemente Estable, Avenida Italia 3318, Montevideo, CP 11600, Uruguay
- Sección Entomología. Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, CP 11400, Uruguay
| | - Miquel A. Arnedo
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Av. Diagonal 643, Barcelona, CP 08028, Spain
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9
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Fungal species boundaries in the genomics era. Fungal Genet Biol 2019; 131:103249. [PMID: 31279976 DOI: 10.1016/j.fgb.2019.103249] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/21/2019] [Accepted: 06/28/2019] [Indexed: 12/30/2022]
Abstract
Genomic data has opened new possibilities to understand how organisms change over time, and could enable the discovery of previously undescribed species. Although taxonomy used to be based on phenotypes, molecular data has frequently revealed that morphological traits are insufficient to describe biodiversity. Genomics holds the promise of revealing even more genetic discontinuities, but the parameters on how to describe species from genomic data remain unclear. Fungi have been a successful case in which the use of molecular markers has uncovered the existence of genetic boundaries where no crosses are possible. In this minireview, we highlight recent advances, propose a set of standards to use genomic sequences to uncover species boundaries, point out potential pitfalls, and present possible future research directions.
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10
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Miles LS, Dyer RJ, Verrelli BC. Urban hubs of connectivity: contrasting patterns of gene flow within and among cities in the western black widow spider. Proc Biol Sci 2018; 285:rspb.2018.1224. [PMID: 30068686 DOI: 10.1098/rspb.2018.1224] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 07/10/2018] [Indexed: 12/20/2022] Open
Abstract
As urbanization drastically alters the natural landscape and generates novel habitats within cities, the potential for changes to gene flow for urban-dwelling species increases. The western black widow spider (Latrodectus hesperus) is a medically relevant urban adapter pest species, for which we have previously identified population genetic signatures consistent with urbanization facilitating gene flow, likely due to human-mediated transport. Here, in an analysis of 1.9 million genome-wide SNPs, we contrast broad-scale geographical analyses of 10 urban and 11 non-urban locales with fine-scale within-city analyses including 30 urban locales across the western USA. These hierarchical datasets enable us to test hypotheses of how urbanization impacts multiple urban cities and their genetic connectivity at different spatial scales. Coupled fine-scale and broad-scale analyses reveal contrasting patterns of high and low genetic differentiation among locales within cities as a result of low and high genetic connectivity, respectively, of these cities to the overall population network. We discuss these results as they challenge the use of cities as replicates of urban eco-evolution, and have implications for conservation and human health in a rapidly growing urban habitat.
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Affiliation(s)
- Lindsay S Miles
- Center for Life Sciences Education, Virginia Commonwealth University, Richmond, VA, USA.,Integrative Life Sciences Doctoral Program, Virginia Commonwealth University, Richmond, VA, USA
| | - Rodney J Dyer
- Center for Environmental Studies, Virginia Commonwealth University, Richmond, VA, USA
| | - Brian C Verrelli
- Center for Life Sciences Education, Virginia Commonwealth University, Richmond, VA, USA .,Department of Biology, Virginia Commonwealth University, Richmond, VA, USA
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11
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Miles LS, Johnson JC, Dyer RJ, Verrelli BC. Urbanization as a facilitator of gene flow in a human health pest. Mol Ecol 2018; 27:3219-3230. [PMID: 29972610 DOI: 10.1111/mec.14783] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/16/2018] [Accepted: 04/11/2018] [Indexed: 01/04/2023]
Abstract
Urban fragmentation can reduce gene flow that isolates populations, reduces genetic diversity and increases population differentiation, all of which have negative conservation implications. Alternatively, gene flow may actually be increased among urban areas consistent with an urban facilitation model. In fact, urban adapter pests are able to thrive in the urban environment and may be experiencing human-mediated transport. Here, we used social network theory with a population genetic approach to investigate the impact of urbanization on genetic connectivity in the Western black widow spider, as an urban pest model of human health concern. We collected genomewide single nucleotide polymorphism variation from mitochondrial and nuclear double-digest RAD (ddRAD) sequence data sets from 210 individuals sampled from 11 urban and 10 nonurban locales across its distribution of the Western United States. From urban and nonurban contrasts of population, phylogenetic, and network analyses, urban locales have higher within-population genetic diversity, lower between-population genetic differentiation and higher estimates of genetic connectivity. Social network analyses show that urban locales not only have more connections, but can act as hubs that drive connectivity among nonurban locales, which show signatures of historical isolation. These results are consistent with an urban facilitation model of gene flow and demonstrate the importance of sampling multiple cities and markers to identify the role that urbanization has had on larger spatial scales. As the urban landscape continues to grow, this approach will help determine what factors influence the spread and adaptation of pests, like the venomous black widow spider, in building policies for human and biodiversity health.
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Affiliation(s)
- Lindsay S Miles
- Center for Life Sciences Education, Virginia Commonwealth University, Richmond, Virginia
- Integrative Life Sciences Doctoral Program, Virginia Commonwealth University, Richmond, Virginia
| | - J Chadwick Johnson
- Division of Mathematical and Natural Sciences, Arizona State University at the West Campus, Glendale, Arizona
| | - Rodney J Dyer
- Center for Environmental Studies, Virginia Commonwealth University, Richmond, Virginia
| | - Brian C Verrelli
- Center for Life Sciences Education, Virginia Commonwealth University, Richmond, Virginia
- Department of Biology, Virginia Commonwealth University, Richmond, Virginia
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12
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Burns M, Hedin M, Tsurusaki N. Population genomics and geographical parthenogenesis in Japanese harvestmen (Opiliones, Sclerosomatidae, Leiobunum). Ecol Evol 2018; 8:36-52. [PMID: 29321849 PMCID: PMC5756897 DOI: 10.1002/ece3.3605] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 10/09/2017] [Accepted: 10/11/2017] [Indexed: 01/03/2023] Open
Abstract
Naturally occurring population variation in reproductive mode presents an opportunity for researchers to test hypotheses regarding the evolution of sex. Asexual reproduction frequently assumes a geographical pattern, in which parthenogenesis-dominated populations are more broadly dispersed than their sexual conspecifics. We evaluate the geographical distribution of genomic signatures associated with parthenogenesis using nuclear and mitochondrial DNA sequence data from two Japanese harvestman sister taxa, Leiobunum manubriatum and Leiobunum globosum. Asexual reproduction is putatively facultative in these species, and female-biased localities are common in habitat margins. Past karyotypic and current cytometric work indicates L. globosum is entirely tetraploid, while L. manubriatum may be either diploid or tetraploid. We estimated species phylogeny, genetic differentiation, diversity, and mitonuclear discordance in females collected across the species range in order to identify range expansion toward marginal habitat, potential for hybrid origin, and persistence of asexual lineages. Our results point to northward expansion of a tetraploid ancestor of L. manubriatum and L. globosum, coupled with support for greater male gene flow in southern L. manubriatum localities. Specimens from localities in the Tohoku and Hokkaido regions were indistinct, particularly those of L. globosum, potentially due to little mitochondrial differentiation or haplotypic variation. Although L. manubriatum overlaps with L. globosum across its entire range, L. globosum was reconstructed as monophyletic with strong support using mtDNA, and marginal support with nuclear loci. Ultimately, we find evidence for continued sexual reproduction in both species and describe opportunities to clarify the rate and mechanism of parthenogenesis.
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Affiliation(s)
- Mercedes Burns
- Department of BiologySan Diego State UniversitySan DiegoCAUSA
- Department of Biological SciencesUniversity of MarylandBaltimore County, BaltimoreMDUSA
| | - Marshal Hedin
- Department of BiologySan Diego State UniversitySan DiegoCAUSA
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13
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Turner SP, Longhorn SJ, Hamilton CA, Gabriel R, PÉrez-Miles F, Vogler AP. Re-evaluating conservation priorities of New World tarantulas (Araneae: Theraphosidae) in a molecular framework indicates non-monophyly of the genera, Aphonopelma and Brachypelma. SYST BIODIVERS 2017. [DOI: 10.1080/14772000.2017.1346719] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Steven P. Turner
- The Natural History Museum (NHM), Cromwell Road, South Kensington, London, UK
- Beneficial Insect Laboratory, North Carolina Department of Agriculture and Consumer Services, Cary, North Carolina, USA
| | | | - Chris A. Hamilton
- Auburn University Museum of Natural History (AUMNH), and Dept. Biological Sciences, Auburn University, Auburn, Alabama, USA
| | - Ray Gabriel
- Oxford Museum of Natural History (OUMNH), Parks Road, Oxford, UK
| | | | - Alfried P. Vogler
- The Natural History Museum (NHM), Cromwell Road, South Kensington, London, UK
- Imperial College London, South Kensington, London, UK
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