51
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Barley AJ, Cordes JE, Walker JM, Thomson RC. Genetic diversity and the origins of parthenogenesis in the teiid lizard Aspidoscelis laredoensis. Mol Ecol 2021; 31:266-278. [PMID: 34614250 DOI: 10.1111/mec.16213] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 09/14/2021] [Accepted: 09/30/2021] [Indexed: 01/25/2023]
Abstract
Unisexual vertebrates typically form through hybridization events between sexual species in which reproductive mode transitions occur in the hybrid offspring. This evolutionary history is thought to have important consequences for the ecology of unisexual lineages and their interactions with congeners in natural communities. However, these consequences have proven challenging to study owing to uncertainty about patterns of population genetic diversity in unisexual lineages. Of particular interest is resolving the contribution of historical hybridization events versus post formational mutation to patterns of genetic diversity in nature. Here we use restriction site associated DNA genotyping to evaluate genetic diversity and demographic history in Aspidoscelis laredoensis, a diploid unisexual lizard species from the vicinity of the Rio Grande River in southern Texas and northern Mexico. The sexual progenitor species from which one or more lineages are derived also occur in the Rio Grande Valley region, although patterns of distribution across individual sites are quite variable. Results from population genetic and phylogenetic analyses resolved the major axes of genetic variation in this species and highlight how these match predictions based on historical patterns of hybridization. We also found discordance between results of demographic modelling using different statistical approaches with the genomic data. We discuss these insights within the context of the ecological and evolutionary mechanisms that generate and maintain lineage diversity in unisexual species. As one of the most dynamic, intriguing, and geographically well investigated groups of whiptail lizards, these species hold substantial promise for future studies on the constraints of diversification in unisexual vertebrates.
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Affiliation(s)
- Anthony J Barley
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'I, USA
| | - James E Cordes
- Division of Sciences and Mathematics, Louisiana State University Eunice, Eunice, Louisiana, USA
| | - James M Walker
- Department of Biological Sciences, University of Arkansas, Fayetteville, Arkansas, USA
| | - Robert C Thomson
- School of Life Sciences, University of Hawai'i, Honolulu, Hawai'I, USA
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52
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Burbrink FT, Ruane S. Contemporary Philosophy and Methods for Studying Speciation and Delimiting Species. ICHTHYOLOGY & HERPETOLOGY 2021. [DOI: 10.1643/h2020073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Frank T. Burbrink
- Department of Herpetology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024; . Send reprint requests to this address
| | - Sara Ruane
- Earth and Environmental Sciences: Ecology and Evolution, Rutgers University–Newark, 195 University Avenue, Newark, New Jersey 07102
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53
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Li J, Zhang Y, Ruhsam M, Milne RI, Wang Y, Wu D, Jia S, Tao T, Mao K. Seeing through the hedge: Phylogenomics of Thuja (Cupressaceae) reveals prominent incomplete lineage sorting and ancient introgression for Tertiary relict flora. Cladistics 2021; 38:187-203. [PMID: 34551153 DOI: 10.1111/cla.12491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/15/2021] [Accepted: 08/27/2021] [Indexed: 12/16/2022] Open
Abstract
The Eastern Asia (EA) - North America (NA) disjunction is a well-known biogeographic pattern of the Tertiary relict flora; however, few studies have investigated the evolutionary history of this disjunction using a phylogenomic approach. Here, we used 2369 single copy nuclear genes and nearly full plastomes to reconstruct the evolutionary history of the small Tertiary relict genus Thuja, which consists of five disjunctly distributed species. The nuclear species tree strongly supported an EA clade Thuja standishii-Thuja sutchuenensis and a "disjunct clade", where western NA species T. plicata is sister to an EA-eastern NA disjunct Thuja occidentalis-Thuja koraiensis group. Our results suggested that the observed topological discordance among the gene trees as well as the cytonuclear discordance is mainly due to incomplete lineage sorting, probably facilitated by the fast diversification of Thuja around the Early Miocene and the large effective population sizes of ancestral lineages. Furthermore, approximately 20% of the T. sutchuenensis nuclear genome is derived from an unknown ancestral lineage of Thuja, which might explain the close resemblance of its cone morphology to that of an ancient fossil species. Overall, our study demonstrates that single genes may not resolve interspecific relationships for disjunct taxa, and that more reliable results will come from hundreds or thousands of loci, revealing a more complex evolutionary history. This will steadily improve our understanding of their origin and evolution.
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Affiliation(s)
- Jialiang Li
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Yujiao Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Markus Ruhsam
- Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh, EH3 5LR, UK
| | - Richard Ian Milne
- Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3JH, UK
| | - Yi Wang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Dayu Wu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Shiyu Jia
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Tongzhou Tao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China
| | - Kangshan Mao
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, Sichuan, 610065, China.,College of Science, Tibet University, Lhasa, Xizang Autonomous Region, 850012, China
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54
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Forthman M, Braun EL, Kimball RT. Gene tree quality affects empirical coalescent branch length estimation. ZOOL SCR 2021. [DOI: 10.1111/zsc.12512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Michael Forthman
- Department of Entomology & Nematology University of Florida Gainesville FL USA
- California State Collection of Arthropods Plant Pest Diagnostics Branch California Department of Food & Agriculture Sacramento CA USA
| | - Edward L. Braun
- Department of Biology University of Florida Gainesville FL USA
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55
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Firneno TJ, O’Neill JR, Itgen MW, Kihneman TA, Townsend JH, Fujita MK. Delimitation despite discordance: Evaluating the species limits of a confounding species complex in the face of mitonuclear discordance. Ecol Evol 2021; 11:12739-12753. [PMID: 34594535 PMCID: PMC8462145 DOI: 10.1002/ece3.8018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 11/24/2022] Open
Abstract
The delimitation of species is an essential pursuit of biology, and proper taxonomies are crucial for the assessment and conservation management of organismal diversity. However, delimiting species can be hindered by a number of factors including highly conserved morphologies (e.g., cryptic species), differences in criteria of species concepts, lineages being in the early stages of the speciation or divergence process, and discordance between gene topologies (e.g., mitonuclear discordance). Here we use a taxonomically confounded species complex of toads in Central America that exhibits extensive mitonuclear discordance to test delimitation hypotheses. Our investigation integrates mitochondrial sequences, nuclear SNPs, morphology, and macroecological data to determine which taxonomy best explains the divergence and evolutionary relationships among these toads. We found that a three species taxonomy following the distributions of the nuclear SNP haplotypes offers the best explanation of the species in this complex based off of the integrated data types. Due to the taxonomic instability of this group, we also discuss conservation concerns in the face of improper taxonomic delimitation. Our study provides an empirical and integrative hypothesis testing framework to assess species delimitation hypotheses in the face of cryptic morphology and mitonuclear discordance and highlights the importance that a stable taxonomy has over conservation-related actions.
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Affiliation(s)
- Thomas J. Firneno
- Department of BiologyUniversity of Texas at ArlingtonArlingtonTXUSA
- Department of Biology, Amphibian and Reptile Diversity Research CenterUniversity of Texas at ArlingtonArlingtonTXUSA
| | | | | | | | - Josiah H. Townsend
- Department of BiologyIndiana University of PennsylvaniaIndianaPAUSA
- Departamento de Ambiente y DesarrolloCentro Zamorano de BiodiversidadEscuela Agrícola Panamericana ZamoranoMunicipalidad de San Antonio de OrienteFrancisco MorazánHonduras
| | - Matthew K. Fujita
- Department of BiologyUniversity of Texas at ArlingtonArlingtonTXUSA
- Department of Biology, Amphibian and Reptile Diversity Research CenterUniversity of Texas at ArlingtonArlingtonTXUSA
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56
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Zhang D, Rheindt FE, She H, Cheng Y, Song G, Jia C, Qu Y, Alström P, Lei F. Most Genomic Loci Misrepresent the Phylogeny of an Avian Radiation Because of Ancient Gene Flow. Syst Biol 2021; 70:961-975. [PMID: 33787929 PMCID: PMC8357342 DOI: 10.1093/sysbio/syab024] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 03/24/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Phylogenetic trees based on genome-wide sequence data may not always represent the true evolutionary history for a variety of reasons. One process that can lead to incorrect reconstruction of species phylogenies is gene flow, especially if interspecific gene flow has affected large parts of the genome. We investigated phylogenetic relationships within a clade comprising eight species of passerine birds (Phylloscopidae, Phylloscopus, leaf warblers) using one de novo genome assembly and 78 resequenced genomes. On the basis of hypothesis-exclusion trials based on D-statistics, phylogenetic network analysis, and demographic inference analysis, we identified ancient gene flow affecting large parts of the genome between one species and the ancestral lineage of a sister species pair. This ancient gene flow consistently caused erroneous reconstruction of the phylogeny when using large amounts of genome-wide sequence data. In contrast, the true relationships were captured when smaller parts of the genome were analyzed, showing that the "winner-takes-all democratic majority tree" is not necessarily the true species tree. Under this condition, smaller amounts of data may sometimes avoid the effects of gene flow due to stochastic sampling, as hidden reticulation histories are more likely to emerge from the use of larger data sets, especially whole-genome data sets. In addition, we also found that genomic regions affected by ancient gene flow generally exhibited higher genomic differentiation but a lower recombination rate and nucleotide diversity. Our study highlights the importance of considering reticulation in phylogenetic reconstructions in the genomic era.[Bifurcation; introgression; recombination; reticulation; Phylloscopus.].
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Affiliation(s)
- Dezhi Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Frank E Rheindt
- Department of Biological Sciences, National University of Singapore, Singapore 117543, Republic of Singapore
| | - Huishang She
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 101408, China
| | - Yalin Cheng
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Gang Song
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chenxi Jia
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanhua Qu
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Per Alström
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden
| | - Fumin Lei
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing 101408, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming 650201, China
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57
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Guinand B, Oral M, Tougard C. Brown trout phylogenetics: A persistent mirage towards (too) many species. JOURNAL OF FISH BIOLOGY 2021; 99:298-307. [PMID: 33483952 DOI: 10.1111/jfb.14686] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/28/2020] [Accepted: 01/19/2021] [Indexed: 06/12/2023]
Affiliation(s)
- Bruno Guinand
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Münevver Oral
- Faculty of Fisheries and Aquatic Science, Recep Tayyip Erdogan University, Rize, Turkey
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58
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Huang J, Bennett J, Flouri T, Leaché AD, Yang Z. Phase Resolution of Heterozygous Sites in Diploid Genomes is Important to Phylogenomic Analysis under the Multispecies Coalescent Model. Syst Biol 2021; 71:334-352. [PMID: 34143216 PMCID: PMC8977997 DOI: 10.1093/sysbio/syab047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 06/03/2021] [Accepted: 06/21/2021] [Indexed: 01/01/2023] Open
Abstract
Genome sequencing projects routinely generate haploid consensus sequences from diploid
genomes, which are effectively chimeric sequences with the phase at heterozygous sites
resolved at random. The impact of phasing errors on phylogenomic analyses under the
multispecies coalescent (MSC) model is largely unknown. Here, we conduct a computer
simulation to evaluate the performance of four phase-resolution strategies (the true phase
resolution, the diploid analytical integration algorithm which averages over all phase
resolutions, computational phase resolution using the program PHASE, and random
resolution) on estimation of the species tree and evolutionary parameters in analysis of
multilocus genomic data under the MSC model. We found that species tree estimation is
robust to phasing errors when species divergences were much older than average coalescent
times but may be affected by phasing errors when the species tree is shallow. Estimation
of parameters under the MSC model with and without introgression is affected by phasing
errors. In particular, random phase resolution causes serious overestimation of population
sizes for modern species and biased estimation of cross-species introgression probability.
In general, the impact of phasing errors is greater when the mutation rate is higher, the
data include more samples per species, and the species tree is shallower with recent
divergences. Use of phased sequences inferred by the PHASE program produced small biases
in parameter estimates. We analyze two real data sets, one of East Asian brown frogs and
another of Rocky Mountains chipmunks, to demonstrate that heterozygote phase-resolution
strategies have similar impacts on practical data analyses. We suggest that genome
sequencing projects should produce unphased diploid genotype sequences if fully phased
data are too challenging to generate, and avoid haploid consensus sequences, which have
heterozygous sites phased at random. In case the analytical integration algorithm is
computationally unfeasible, computational phasing prior to population genomic analyses is
an acceptable alternative. [BPP; introgression; multispecies coalescent; phase; species
tree.]
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Affiliation(s)
- Jun Huang
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.,Department of Mathematics, Beijing Jiaotong University, Beijing, 100044, P.R. China
| | - Jeremy Bennett
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.,Department of Ecology and Evolutionary Biology, University of Connecticut, 75 N. Eagleville Road, Unit 3043, Storrs, CT 06269-3043, USA
| | - Tomáš Flouri
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Adam D Leaché
- Department of Biology & Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195-1800, USA
| | - Ziheng Yang
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
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59
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Yoder AD, Tiley GP. The challenge and promise of estimating the de novo mutation rate from whole-genome comparisons among closely related individuals. Mol Ecol 2021; 30:6087-6100. [PMID: 34062029 DOI: 10.1111/mec.16007] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 04/22/2021] [Accepted: 05/26/2021] [Indexed: 12/20/2022]
Abstract
Germline mutations are the raw material for natural selection, driving species evolution and the generation of earth's biodiversity. Without this driver of genetic diversity, life on earth would stagnate. Yet, it is a double-edged sword. An excess of mutations can have devastating effects on fitness and population viability. It is therefore one of the great challenges of molecular ecology to determine the rate and mechanisms by which these mutations accrue across the tree of life. Advances in high-throughput sequencing technologies are providing new opportunities for characterizing the rates and mutational spectra within species and populations thus informing essential evolutionary parameters such as the timing of speciation events, the intricacies of historical demography, and the degree to which lineages are subject to the burdens of mutational load. Here, we will focus on both the challenge and promise of whole-genome comparisons among parents and their offspring from known pedigrees for the detection of germline mutations as they arise in a single generation. The potential of these studies is high, but the field is still in its infancy and much uncertainty remains. Namely, the technical challenges are daunting given that pedigree-based genome comparisons are essentially searching for needles in a haystack given the very low signal to noise ratio. Despite the challenges, we predict that rapidly developing methods for whole-genome comparisons hold great promise for integrating empirically derived estimates of de novo mutation rates and mutation spectra across many molecular ecological applications.
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Affiliation(s)
- Anne D Yoder
- Department of Biology, Duke University, Durham, NC, USA
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60
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Inference of gene flow in the process of speciation: Efficient maximum-likelihood implementation of a generalised isolation-with-migration model. Theor Popul Biol 2021; 140:1-15. [PMID: 33736959 DOI: 10.1016/j.tpb.2021.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 02/28/2021] [Accepted: 03/01/2021] [Indexed: 11/21/2022]
Abstract
The 'isolation with migration' (IM) model has been extensively used in the literature to detect gene flow during the process of speciation. In this model, an ancestral population split into two or more descendant populations which subsequently exchanged migrants at a constant rate until the present. Of course, the assumption of constant gene flow until the present is often over-simplistic in the context of speciation. In this paper, we consider a 'generalised IM' (GIM) model: a two-population IM model in which migration rates and population sizes are allowed to change at some point in the past. By developing a maximum-likelihood implementation of this model, we enable inference on both historical and contemporary rates of gene flow between two closely related populations or species. The GIM model encompasses both the standard two-population IM model and the 'isolation with initial migration' (IIM) model as special cases, as well as a model of secondary contact. We examine for simulated data how our method can be used, by means of likelihood ratio tests or AIC scores, to distinguish between the following scenarios of population divergence: (a) divergence in complete isolation; (b) divergence with a period of gene flow followed by isolation; (c) divergence with a period of isolation followed by secondary contact; (d) divergence with ongoing gene flow. Our method is based on the coalescent and is suitable for data sets consisting of the number of nucleotide differences between one pair of DNA sequences at each of a large number of independent loci. As our method relies on an explicit expression for the likelihood, it is computationally very fast.
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61
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Sánchez KI, Avila LJ, Sites JW, Morando M. An integrative approach to address species limits in the southernmost members of the Liolaemus kingii group (Squamata: Liolaemini). Mol Phylogenet Evol 2021; 157:107046. [PMID: 33421613 DOI: 10.1016/j.ympev.2020.107046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 11/07/2020] [Accepted: 12/14/2020] [Indexed: 11/28/2022]
Abstract
Recent conceptual and methodological advances have enabled an increasing number of studies to address the problem of species delimitation in a comprehensive manner. This is of particular interest in cases of species whose divergence times are recent and/or effective population sizes are large, where the conclusions obtained from a single source of evidence may lead to erroneous estimations of true species numbers or incorrect assignment of individuals to species. Iguanian lizards of the Liolaemus kingii group (13 species) comprise an important component of the endemic fauna of Patagonia. The southernmost species of this group (namely L. baguali, L. escarchadosi, L. sarmientoi, and L. tari) show widely overlapping distributions across southern Patagonia, also, their phylogenetic relationships are ambiguous and species boundaries have not been explicitly tested. Here we use a comprehensive approach to assess species limits through the use of molecular and morphological information (mitochondrial cytb, nuclear sequences collected by ddRADseq, and linear, meristic and landmark-based morphometrics). We found support for the current taxonomy given that the different analyses recognized the nominal species (4 entities), also a candidate species was supported by mitochondrial and morphological data. In addition, we detected signs of admixture between some of the species. Our results indicate that the L. kingii group can serve as a model system in studies of diversification accompanied by hybridization in nature, which in turn might have been promoted by past climatic oscillations and generalist morphologies. We emphasize the importance of using multiple lines of evidence in order to solve evolutionary stories, and minimizing potential erroneous results that may arise when relying on a single source of information.
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Affiliation(s)
- Kevin I Sánchez
- Instituto Patagónico para el Estudio de los Ecosistemas Continentales, Consejo Nacional de Investigaciones Científicas y Técnicas (IPEEC-CONICET), Boulevard Almirante Brown 2915, Puerto Madryn, CT U9120ACD, Argentina.
| | - Luciano J Avila
- Instituto Patagónico para el Estudio de los Ecosistemas Continentales, Consejo Nacional de Investigaciones Científicas y Técnicas (IPEEC-CONICET), Boulevard Almirante Brown 2915, Puerto Madryn, CT U9120ACD, Argentina
| | - Jack W Sites
- Department of Biology and M.L. Bean Life Science Museum, Brigham Young University (BYU), Provo, UT 84602, USA
| | - Mariana Morando
- Instituto Patagónico para el Estudio de los Ecosistemas Continentales, Consejo Nacional de Investigaciones Científicas y Técnicas (IPEEC-CONICET), Boulevard Almirante Brown 2915, Puerto Madryn, CT U9120ACD, Argentina
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62
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Alström P, van Linschooten J, Donald PF, Sundev G, Mohammadi Z, Ghorbani F, Shafaeipour A, van den Berg A, Robb M, Aliabadian M, Wei C, Lei F, Oxelman B, Olsson U. Multiple species delimitation approaches applied to the avian lark genus Alaudala. Mol Phylogenet Evol 2020; 154:106994. [PMID: 33250446 DOI: 10.1016/j.ympev.2020.106994] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 10/18/2020] [Accepted: 10/19/2020] [Indexed: 11/16/2022]
Abstract
Species delimitation has advanced from a purely phenotypic exercise to a branch of science that integrates multiple sources of data to identify independently evolving lineages that can be treated as species. We here test species limits in the avian Lesser Short-toed Lark Alaudala rufesens-Sand Lark A. raytal complex, which has an intricate taxonomic history, ranging from a single to three recognised species, with different inclusiveness in different treatments. Our integrative taxonomic approach is based on a combination of DNA sequences, plumage, biometrics, songs, song-flights, geographical distributions, habitat, and bioclimatic data, and using various methods including a species delimitation program (STACEY) based on the multispecies coalescent model. We propose that four species should be recognised: Lesser Short-toed Lark A. rufescens (sensu stricto), Heine's Short-toed Lark A. heinei, Asian Short-toed Lark A. cheleensis and Sand Lark A. raytal. There is also some evidence suggesting lineage separation within A. cheleensis and A. raytal, but additional data are required to evaluate this. The species delimitation based on STACEY agrees well with the non-genetic data. Although computer-based species delimitation programs can be useful in identifying independently evolving lineages, we stress that whenever possible, species hypotheses proposed by these programs should be tested by independent, non-genetic data. Our results highlight the difficulty and subjectivity of delimiting lineages and species, especially at early stages in the speciation process.
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Affiliation(s)
- Per Alström
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden; Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Jip van Linschooten
- Animal Ecology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18 D, SE-752 36 Uppsala, Sweden
| | - Paul F Donald
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Gombobaatar Sundev
- National University of Mongolia and Mongolian Ornithological Society, P.O. Box 537, Ulaanbaatar 210646a, Ulaanbaatar, Mongolia
| | - Zeinolabedin Mohammadi
- Department of Biology and Research Department of Zoological Innovation, Institute of Applied Zoology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Fatemeh Ghorbani
- Department of Biology and Research Department of Zoological Innovation, Institute of Applied Zoology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Arya Shafaeipour
- Department of Biology, Faculty of Science, Yasouj University, Yasouj, Iran
| | - Arnoud van den Berg
- The Sound Approach, c/o Duinlustparkweg 98, 2082 EG Santpoort-Zuid, the Netherlands
| | - Magnus Robb
- The Sound Approach, c/o Rua Dr Pedro Almeida Lima 6, 2710-122 Sintra, Portugal
| | - Mansour Aliabadian
- Department of Biology and Research Department of Zoological Innovation, Institute of Applied Zoology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Chentao Wei
- State Key Laboratory of Biocontrol, Department of Ecology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Fumin Lei
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Bengt Oxelman
- Systematics and Biodiversity, Department of Biology and Environmental Sciences, University of Gothenburg, Box 463, SE-405 30 Göteborg, Sweden; Gothenburg Global Biodiversity Centre, Box 461, SE-405 30 Gothenburg, Sweden
| | - Urban Olsson
- Systematics and Biodiversity, Department of Biology and Environmental Sciences, University of Gothenburg, Box 463, SE-405 30 Göteborg, Sweden; Gothenburg Global Biodiversity Centre, Box 461, SE-405 30 Gothenburg, Sweden
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Molecular Clocks without Rocks: New Solutions for Old Problems. Trends Genet 2020; 36:845-856. [PMID: 32709458 DOI: 10.1016/j.tig.2020.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 06/02/2020] [Accepted: 06/11/2020] [Indexed: 02/07/2023]
Abstract
Molecular data have been used to date species divergences ever since they were described as documents of evolutionary history in the 1960s. Yet, an inadequate fossil record and discordance between gene trees and species trees are persistently problematic. We examine how, by accommodating gene tree discordance and by scaling branch lengths to absolute time using mutation rate and generation time, multispecies coalescent (MSC) methods can potentially overcome these challenges. We find that time estimates can differ - in some cases, substantially - depending on whether MSC methods or traditional phylogenetic methods that apply concatenation are used, and whether the tree is calibrated with pedigree-based mutation rates or with fossils. We discuss the advantages and shortcomings of both approaches and provide practical guidance for data analysis when using these methods.
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Huang J, Flouri T, Yang Z. A Simulation Study to Examine the Information Content in Phylogenomic Data Sets under the Multispecies Coalescent Model. Mol Biol Evol 2020; 37:3211-3224. [DOI: 10.1093/molbev/msaa166] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
AbstractWe use computer simulation to examine the information content in multilocus data sets for inference under the multispecies coalescent model. Inference problems considered include estimation of evolutionary parameters (such as species divergence times, population sizes, and cross-species introgression probabilities), species tree estimation, and species delimitation based on Bayesian comparison of delimitation models. We found that the number of loci is the most influential factor for almost all inference problems examined. Although the number of sequences per species does not appear to be important to species tree estimation, it is very influential to species delimitation. Increasing the number of sites and the per-site mutation rate both increase the mutation rate for the whole locus and these have the same effect on estimation of parameters, but the sequence length has a greater effect than the per-site mutation rate for species tree estimation. We discuss the computational costs when the data size increases and provide guidelines concerning the subsampling of genomic data to enable the application of full-likelihood methods of inference.
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Affiliation(s)
- Jun Huang
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- Department of Mathematics, Beijing Jiaotong University, Beijing, P.R. China
| | - Tomáš Flouri
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Ziheng Yang
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
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Jiao X, Yang Z. Defining Species When There is Gene Flow. Syst Biol 2020; 70:108-119. [PMID: 32617579 DOI: 10.1093/sysbio/syaa052] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 06/23/2020] [Accepted: 06/23/2020] [Indexed: 12/20/2022] Open
Abstract
Whatever one's definition of species, it is generally expected that individuals of the same species should be genetically more similar to each other than they are to individuals of another species. Here, we show that in the presence of cross-species gene flow, this expectation may be incorrect. We use the multispecies coalescent model with continuous-time migration or episodic introgression to study the impact of gene flow on genetic differences within and between species and highlight a surprising but plausible scenario in which different population sizes and asymmetrical migration rates cause a genetic sequence to be on average more closely related to a sequence from another species than to a sequence from the same species. Our results highlight the extraordinary impact that even a small amount of gene flow may have on the genetic history of the species. We suggest that contrasting long-term migration rate and short-term hybridization rate, both of which can be estimated using genetic data, may be a powerful approach to detecting the presence of reproductive barriers and to define species boundaries.[Gene flow; introgression; migration; multispecies coalescent; species concept; species delimitation.].
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Affiliation(s)
- Xiyun Jiao
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Ziheng Yang
- Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
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Abstract
Knowing phylogenetic relationships among species is fundamental for many studies in biology. An accurate phylogenetic tree underpins our understanding of the major transitions in evolution, such as the emergence of new body plans or metabolism, and is key to inferring the origin of new genes, detecting molecular adaptation, understanding morphological character evolution and reconstructing demographic changes in recently diverged species. Although data are ever more plentiful and powerful analysis methods are available, there remain many challenges to reliable tree building. Here, we discuss the major steps of phylogenetic analysis, including identification of orthologous genes or proteins, multiple sequence alignment, and choice of substitution models and inference methodologies. Understanding the different sources of errors and the strategies to mitigate them is essential for assembling an accurate tree of life.
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