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Reppa A, Agori AF, Santikou P, Parmakelis A, Pafilis P, Valakos ED, Sagonas K. Small Island Effects on the Thermal Biology of the Endemic Mediterranean Lizard Podarcis gaigeae. Animals (Basel) 2023; 13:2965. [PMID: 37760365 PMCID: PMC10525772 DOI: 10.3390/ani13182965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 09/07/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Ectotherms are vastly affected by climatic conditions as they rely on external sources of heat to regulate their body temperature, and changes in their habitat thermal quality could seriously affect their overall biology. To overcome the problems of a thermally unfavorable habitat, lizards need to either adjust their thermoregulatory behavior or respond to directional selection and shift their preferred body temperatures. To assess the impact of habitat thermal quality on the thermoregulatory profile, we studied multiple islet and 'mainland' populations of the Skyros wall lizard Podarcis gaigeae, an endemic lacertid to Skyros Archipelago, Greece. We evaluated the effectiveness of thermoregulation (E) using the three main thermal parameters: body (Tb), operative (Te), and preferred (Tpref) temperatures. We first hypothesized that the spatial homogeneity, the scarcity of thermal shelters, and the exposure to higher winds on islets would result in more demanding climate conditions. Second, we anticipated that islet lizards would achieve higher E in response to the lower thermal quality therein. As hypothesized, thermal parameters differed between populations but not in the expected manner. Skyros 'mainland' habitats reached higher temperatures, had more intense fluctuations, and were of lower thermal quality. As a result, lizards showed higher accuracy, precision, and effectiveness of thermoregulation. Noteworthy, we found that lizards from different populations have shifted their thermal profile and preferred body temperatures to cope with the particular conditions prevailing in their habitats. The latter supports the labile view on the evolution of thermoregulation.
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Affiliation(s)
- Aikaterini Reppa
- Section of Ecology and Taxonomy, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Ariadne Faidra Agori
- Section of Animal and Human Physiology, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Panayiota Santikou
- Section of Animal and Human Physiology, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Aristeidis Parmakelis
- Section of Ecology and Taxonomy, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Panayiotis Pafilis
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece; (P.P.); (E.D.V.)
- Zoological Museum, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Efstratios D. Valakos
- Section of Zoology and Marine Biology, Department of Biology, National and Kapodistrian University of Athens, 157 72 Athens, Greece; (P.P.); (E.D.V.)
- Zoological Museum, National and Kapodistrian University of Athens, 157 72 Athens, Greece
| | - Kostas Sagonas
- Section of Zoology, Department of Biology, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece
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2
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Hill P, Wapstra E, Ezaz T, Burridge CP. Pleistocene divergence in the absence of gene flow among populations of a viviparous reptile with intraspecific variation in sex determination. Ecol Evol 2021; 11:5575-5583. [PMID: 34026030 PMCID: PMC8131762 DOI: 10.1002/ece3.7458] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 02/21/2021] [Accepted: 02/25/2021] [Indexed: 12/26/2022] Open
Abstract
Polymorphisms can lead to genetic isolation if there is differential mating success among conspecifics divergent for a trait. Polymorphism for sex-determining system may fall into this category, given strong selection for the production of viable males and females and the low success of heterogametic hybrids when sex chromosomes differ (Haldane's rule). Here we investigated whether populations exhibiting polymorphism for sex determination are genetically isolated, using the viviparous snow skink Carinascincus ocellatus. While a comparatively high elevation population has genotypic sex determination, in a lower elevation population there is an additional temperature component to sex determination. Based on 11,107 SNP markers, these populations appear genetically isolated. "Isolation with Migration" analysis also suggests these populations diverged in the absence of gene flow, across a period encompassing multiple Pleistocene glaciations and likely greater geographic proximity of populations. However, further experiments are required to establish whether genetic isolation may be a cause or consequence of differences in sex determination. Given the influence of temperature on sex in one lineage, we also discuss the implications for the persistence of this polymorphism under climate change.
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Affiliation(s)
- Peta Hill
- Discipline of Biological SciencesUniversity of TasmaniaSandy BayTas.Australia
| | - Erik Wapstra
- Discipline of Biological SciencesUniversity of TasmaniaSandy BayTas.Australia
| | - Tariq Ezaz
- Institute for Applied EcologyUniversity of CanberraBruceACTAustralia
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3
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Yang B, Zhang G, Guo F, Wang M, Wang H, Xiao H. A Genomewide Scan for Genetic Structure and Demographic History of Two Closely Related Species, Rhododendron dauricum and R. mucronulatum ( Rhododendron, Ericaceae). FRONTIERS IN PLANT SCIENCE 2020; 11:1093. [PMID: 32765570 PMCID: PMC7380098 DOI: 10.3389/fpls.2020.01093] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
Understanding the processes of divergence and speciation is an important task for evolutionary research, and climate oscillations play a pivotal role. We estimated the genetic structure and demographic history of two closely related species of Rhododendron, R. dauricum, and R. mucronulatum, distributed in northeastern China using 664,406 single nucleotide polymorphic loci of specific-locus amplified fragment sequencing (SLAF-seq) and 4 chloroplast DNA (cpDNA) fragments, sampling 376 individuals from 39 populations of these two species across their geographic distributions. The geographical distribution of cpDNA haplotypes revealed that R. dauricum and R. mucronulatum have different spatial genetic structures and haplotype diversity. Analysis of molecular variance (AMOVA) results showed that these two species have significant genetic differentiation and that the phylogeny demonstrates that these two species clustered a monophyletic group based on SLAF data, respectively, but not in cpDNA data. The evidence of significant gene flow was also detected from R. mucronulatum to R. dauricum. A deep divergence between the two species was observed and occurred during the early Oligocene. The niche models showed that the two species have different demographic histories. Thus, our results imply that geography and climate changes played important roles in the evolutionary process of R. dauricum and R. mucronulatum, and although there was an interspecific gene flow, the divergence was maintained by natural selection.
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Affiliation(s)
- Baiming Yang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, China
- Changchun Guoxin Modern Agricultural Technology Development Co., Ltd., Changchun, China
| | - Guoli Zhang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, China
| | - Fengping Guo
- Biology Group, No. 30 Middle School of Shenyang, Shenyang, China
| | - Manqi Wang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, China
| | - Huaying Wang
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, China
| | - Hongxing Xiao
- Key Laboratory of Molecular Epigenetics of Ministry of Education, Northeast Normal University, Changchun, China
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4
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Kioukis A, Michalopoulou VA, Briers L, Pirintsos S, Studholme DJ, Pavlidis P, Sarris PF. Intraspecific diversification of the crop wild relative Brassica cretica Lam. using demographic model selection. BMC Genomics 2020; 21:48. [PMID: 31937246 PMCID: PMC6961386 DOI: 10.1186/s12864-019-6439-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 12/29/2019] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Crop wild relatives (CWRs) contain genetic diversity, representing an invaluable resource for crop improvement. Many of their traits have the potential to help crops to adapt to changing conditions that they experience due to climate change. An impressive global effort for the conservation of various CWR will facilitate their use in crop breeding for food security. The genus Brassica is listed in Annex I of the International Treaty on Plant Genetic Resources for Food and Agriculture. Brassica oleracea (or wild cabbage), a species native to southern and western Europe, has become established as an important human food crop plant because of its large reserves stored over the winter in its leaves. Brassica cretica Lam. (Bc) is a CWR in the brassica group and B. cretica subsp. nivea (Bcn) has been suggested as a separate subspecies. The species Bc has been proposed as a potential gene donor to brassica crops, including broccoli, cabbage, cauliflower, oilseed rape, etc. RESULTS: We sequenced genomes of four Bc individuals, including two Bcn and two Bc. Demographic analysis based on our whole-genome sequence data suggests that populations of Bc are not isolated. Classification of the Bc into distinct subspecies is not supported by the data. Using only the non-coding part of the data (thus, the parts of the genome that has evolved nearly neutrally), we find the gene flow between different Bc population is recent and its genomic diversity is high. CONCLUSIONS Despite predictions on the disruptive effect of gene flow in adaptation, when selection is not strong enough to prevent the loss of locally adapted alleles, studies show that gene flow can promote adaptation, that local adaptations can be maintained despite high gene flow, and that genetic architecture plays a fundamental role in the origin and maintenance of local adaptation with gene flow. Thus, in the genomic era it is important to link the selected demographic models with the underlying processes of genomic variation because, if this variation is largely selectively neutral, we cannot assume that a diverse population of crop wild relatives will necessarily exhibit the wide-ranging adaptive diversity required for further crop improvement.
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Affiliation(s)
- Antonios Kioukis
- Institute of Computer Science, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Vassiliki A Michalopoulou
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Laura Briers
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Stergios Pirintsos
- Department of Biology, University of Crete, 714 09, Heraklion, Greece
- Botanical Garden, University of Crete, Gallos Campus, 741 00, Rethymnon, Greece
| | - David J Studholme
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
| | - Pavlos Pavlidis
- Institute of Computer Science, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece
| | - Panagiotis F Sarris
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, 70013, Crete, Greece.
- Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK.
- Department of Biology, University of Crete, 714 09, Heraklion, Greece.
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5
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Chan KO, Brown RM. Elucidating the drivers of genetic differentiation in Malaysian torrent frogs (Anura: Ranidae: Amolops): a landscape genomics approach. Zool J Linn Soc 2019. [DOI: 10.1093/zoolinnean/zlz151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Abstract
The interplay between environmental attributes and evolutionary processes can provide valuable insights into how biodiversity is generated, partitioned and distributed. This study investigates the role of spatial, environmental and historical factors that could potentially drive diversification and shape genetic variation in Malaysian torrent frogs. Torrent frogs are ecologically conserved, and we hypothesize that this could impose tight constraints on dispersal routes, gene flow and consequently genetic structure. Moreover, levels of gene flow were shown to vary among populations from separate mountain ranges, indicating that genetic differentiation could be influenced by landscape features. Using genome-wide single nucleotide polymorphisms, in conjunction with landscape variables derived from Geographic Information Systems, we performed distance-based redundancy analyses and variance partitioning to disentangle the effects of isolation-by-distance (IBD), isolation-by-resistance (IBR) and isolation-by-colonization (IBC). Our results demonstrated that IBR contributed minimally to genetic variation. Intraspecific population structure can be largely attributed to IBD, whereas interspecific diversification was primarily driven by IBC. We also detected two distinct population bottlenecks, indicating that speciation events were likely driven by vicariance or founder events.
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Affiliation(s)
- Kin Onn Chan
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA
- Lee Kong Chian Natural History Museum, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Rafe M Brown
- Biodiversity Institute and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas, USA
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6
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Austin JD, Greene DU, Honeycutt RL, McCleery RA. Genetic evidence indicates ecological divergence rather than geographic barriers structure Florida fox squirrels. J Mammal 2018. [DOI: 10.1093/jmammal/gyy128] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- James D Austin
- Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Daniel U Greene
- Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
| | - Rodney L Honeycutt
- Natural Science Division, Pepperdine University, Pacific Coast Highway, Malibu, CA, USA
| | - Robert A McCleery
- Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, USA
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Spotlight on islands: on the origin and diversification of an ancient lineage of the Italian wall lizard Podarcis siculus in the western Pontine Islands. Sci Rep 2018; 8:15111. [PMID: 30310095 PMCID: PMC6181948 DOI: 10.1038/s41598-018-33326-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Accepted: 09/26/2018] [Indexed: 11/08/2022] Open
Abstract
Groups of proximate continental islands may conceal more tangled phylogeographic patterns than oceanic archipelagos as a consequence of repeated sea level changes, which allow populations to experience gene flow during periods of low sea level stands and isolation by vicariant mechanisms during periods of high sea level stands. Here, we describe for the first time an ancient and diverging lineage of the Italian wall lizard Podarcis siculus from the western Pontine Islands. We used nuclear and mitochondrial DNA sequences of 156 individuals with the aim of unraveling their phylogenetic position, while microsatellite loci were used to test several a priori insular biogeographic models of migration with empirical data. Our results suggest that the western Pontine populations colonized the islands early during their Pliocene volcanic formation, while populations from the eastern Pontine Islands seem to have been introduced recently. The inter-island genetic makeup indicates an important role of historical migration, probably due to glacial land bridges connecting islands followed by a recent vicariant mechanism of isolation. Moreover, the most supported migration model predicted higher gene flow among islands which are geographically arranged in parallel. Considering the threatened status of small insular endemic populations, we suggest this new evolutionarily independent unit be given priority in conservation efforts.
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8
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Psonis N, Antoniou A, Karameta E, Leaché AD, Kotsakiozi P, Darriba D, Kozlov A, Stamatakis A, Poursanidis D, Kukushkin O, Jablonski D, Crnobrnja–Isailović J, Gherghel I, Lymberakis P, Poulakakis N. Resolving complex phylogeographic patterns in the Balkan Peninsula using closely related wall-lizard species as a model system. Mol Phylogenet Evol 2018; 125:100-115. [DOI: 10.1016/j.ympev.2018.03.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 03/08/2018] [Accepted: 03/14/2018] [Indexed: 10/17/2022]
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9
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Fumey J, Hinaux H, Noirot C, Thermes C, Rétaux S, Casane D. Evidence for late Pleistocene origin of Astyanax mexicanus cavefish. BMC Evol Biol 2018; 18:43. [PMID: 29665771 PMCID: PMC5905186 DOI: 10.1186/s12862-018-1156-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 03/19/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Cavefish populations belonging to the Mexican tetra species Astyanax mexicanus are outstanding models to study the tempo and mode of adaptation to a radical environmental change. They are currently assigned to two main groups, the so-called "old" and "new" lineages, which would have populated several caves independently and at different times. However, we do not have yet accurate estimations of the time frames of evolution of these populations. RESULTS We reanalyzed the geographic distribution of mitochondrial and nuclear DNA polymorphisms and we found that these data do not support the existence of two cavefish lineages. Using IMa2, a program that allows dating population divergence in addition to demographic parameters, we found that microsatellite polymorphism strongly supports a very recent origin of cave populations (< 20,000 years). We identified a large number of single-nucleotide polymorphisms (SNPs) in transcript sequences of pools of embryos (Pool-seq) belonging to Pachón cave population and a surface population from Texas. Based on summary statistics that can be computed with this SNP data set together with simulations of evolution of SNP polymorphisms in two recently isolated populations, we looked for sets of demographic parameters that allow the computation of summary statistics with simulated populations that are similar to the ones with the sampled populations. In most simulations for which we could find a good fit between the summary statistics of observed and simulated data, the best fit occurred when the divergence between simulated populations was less than 30,000 years. CONCLUSIONS Although it is often assumed that some cave populations have a very ancient origin, a recent origin of these populations is strongly supported by our analyses of independent sets of nuclear DNA polymorphism. Moreover, the observation of two divergent haplogroups of mitochondrial and nuclear genes with different geographic distributions support a recent admixture of two divergent surface populations, before the isolation of cave populations. If cave populations are indeed only several thousand years old, many phenotypic changes observed in cavefish would thus have mainly involved the fixation of genetic variants present in surface fish populations and within a very short period of time.
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Affiliation(s)
- Julien Fumey
- Évolution, Génomes, Comportement, Écologie, CNRS, IRD, Univ Paris-Sud. Université Paris-Saclay, F-91198, Gif-sur-Yvette, France.,Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, UMR 9198, FRC 3115, Avenue de la Terrasse, Bâtiment 24, Gif-sur-Yvette, F-91198, Paris, France
| | - Hélène Hinaux
- DECA group, Paris-Saclay Institute of Neuroscience, UMR 9197, CNRS, Gif sur Yvette, France
| | - Céline Noirot
- Plateforme Bioinformatique Toulouse, Midi-Pyrénées, UBIA, INRA, Auzeville Castanet-Tolosan, France
| | - Claude Thermes
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, UMR 9198, FRC 3115, Avenue de la Terrasse, Bâtiment 24, Gif-sur-Yvette, F-91198, Paris, France
| | - Sylvie Rétaux
- DECA group, Paris-Saclay Institute of Neuroscience, UMR 9197, CNRS, Gif sur Yvette, France
| | - Didier Casane
- Évolution, Génomes, Comportement, Écologie, CNRS, IRD, Univ Paris-Sud. Université Paris-Saclay, F-91198, Gif-sur-Yvette, France. .,Université Paris Diderot, Sorbonne Paris Cité, Paris, France.
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10
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Maguilla E, Escudero M, Hipp AL, Luceño M. Allopatric speciation despite historical gene flow: Divergence and hybridization in Carex furva and C. lucennoiberica (Cyperaceae) inferred from plastid and nuclear RAD-seq data. Mol Ecol 2017; 26:5646-5662. [PMID: 28742230 DOI: 10.1111/mec.14253] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/29/2017] [Accepted: 06/30/2017] [Indexed: 12/13/2022]
Abstract
Gene flow among incipient species can act as a creative or destructive force in the speciation process, generating variation on which natural selection can act while, potentially, undermining population divergence. The flowering plant genus Carex exhibits a rapid and relatively recent radiation with many species limits still unclear. This is the case with the Iberian Peninsula (Spain and Portugal)-endemic C. lucennoiberica, which lay unrecognized within Carex furva until its recent description as a new species. In this study, we test how these species were impacted by interspecific gene flow during speciation. We sampled the full range of distribution of C. furva (15 individuals sampled) and C. lucennoiberica (88 individuals), sequenced two cpDNA regions (atpI-atpH, psbA-trnH) and performed genomic sequencing of 45,100 SNPs using restriction site-associated DNA sequencing (RAD-seq). We utilized a set of partitioned D-statistic tests and demographic analyses to study the degree and direction of introgression. Additionally, we modelled species distributions to reconstruct changes in range distribution during glacial and interglacial periods. Plastid, nuclear and morphological data strongly support divergence between species with subsequent gene flow. Combined with species distribution modelling, these data support a scenario of allopatry leading to species divergence, followed by secondary contact and gene flow due to long-distance dispersal and/or range expansions and contractions in response to Quaternary glacial cycles. We conclude that this is a case of allopatric speciation despite historical secondary contacts, which could have temporally influenced the speciation process, contributing to the knowledge of forces that are driving or counteracting speciation.
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Affiliation(s)
| | - Marcial Escudero
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain
| | - Andrew L Hipp
- The Morton Arboretum, Lisle, IL, USA.,Botany Department, Field Museum of Natural History, Chicago, IL, USA
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11
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Trewick SA, Pilkington S, Shepherd LD, Gibb GC, Morgan-Richards M. Closing the gap: Avian lineage splits at a young, narrow seaway imply a protracted history of mixed population response. Mol Ecol 2017; 26:5752-5772. [PMID: 28805283 DOI: 10.1111/mec.14323] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/01/2017] [Accepted: 08/07/2017] [Indexed: 12/01/2022]
Abstract
The evolutionary significance of spatial habitat gaps has been well recognized since Alfred Russel Wallace compared the faunas of Bali and Lombok. Gaps between islands influence population structuring of some species, and flightless birds are expected to show strong partitioning even where habitat gaps are narrow. We examined the population structure of the most numerous living flightless land bird in New Zealand, Weka (Gallirallus australis). We surveyed Weka and their feather lice in native and introduced populations using genetic data gathered from DNA sequences of mitochondrial genes and nuclear β-fibrinogen and five microsatellite loci. We found low genetic diversity among extant Weka population samples. Two genetic clusters were evident in the mtDNA from Weka and their lice, but partitioning at nuclear loci was less abrupt. Many formerly recognized subspecies/species were not supported; instead, we infer one subspecies for each of the two main New Zealand islands. Although currently range restricted, North Island Weka have higher mtDNA diversity than the more wide-ranging southern Weka. Mismatch and neutrality statistics indicate North Island Weka experienced rapid and recent population reduction, while South Island Weka display the signature of recent expansion. Similar haplotype data from a widespread flying relative of Weka and other New Zealand birds revealed instances of North Island-South Island partitioning associated with a narrow habitat gap (Cook Strait). However, contrasting patterns indicate priority effects and other ecological factors have a strong influence on spatial exchange at this scale.
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Affiliation(s)
- Steve A Trewick
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - Stephen Pilkington
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - Lara D Shepherd
- Te Papa Tongarewa Museum of New Zealand, Wellington, New Zealand
| | - Gillian C Gibb
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - Mary Morgan-Richards
- Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand
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12
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Hung C, Drovetski SV, Zink RM. The roles of ecology, behaviour and effective population size in the evolution of a community. Mol Ecol 2017; 26:3775-3784. [DOI: 10.1111/mec.14152] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/14/2017] [Accepted: 04/17/2017] [Indexed: 01/06/2023]
Affiliation(s)
- Chih‐Ming Hung
- Biodiversity Research Center Academia Sinica Taipei Taiwan
| | - Sergei V. Drovetski
- Division of Birds National Museum of Natural History Smithsonian Institution Washington DC USA
| | - Robert M. Zink
- School of Natural Resources Nebraska State Museum, and School of Biological Sciences University of Nebraska Lincoln NE USA
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13
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Yang M, He Z, Shi S, Wu CI. Can genomic data alone tell us whether speciation happened with gene flow? Mol Ecol 2017; 26:2845-2849. [PMID: 28345182 DOI: 10.1111/mec.14117] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 03/08/2017] [Accepted: 03/20/2017] [Indexed: 01/02/2023]
Abstract
The allopatric model, which requires a period of geographical isolation for speciation to complete, has been the standard model in the modern era. Recently, "speciation with gene flow" has been widely discussed in relation to the model of "strict allopatry" and the level of DNA divergence across genomic regions. We wish to caution that genomic data by themselves may only permit the rejection of the simplest form of allopatry. Even a slightly more complex and realistic model that starts with subdivided populations would be impossible to reject by the genomic data alone. To resolve this central issue of speciation, other forms of observations such as the sequencing of reproductive isolation genes or the identification of geographical barrier(s) will be necessary.
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Affiliation(s)
- Ming Yang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Ziwen He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Suhua Shi
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chung-I Wu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,Department of Ecology and Evolution, University of Chicago, Chicago, IL, USA
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14
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Sfenthourakis S, Triantis KA. The Aegean archipelago: a natural laboratory of evolution, ecology and civilisations. ACTA ACUST UNITED AC 2017; 24:4. [PMID: 28251115 PMCID: PMC5320758 DOI: 10.1186/s40709-017-0061-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 01/28/2017] [Indexed: 12/29/2022]
Abstract
The Aegean archipelago, comprising numerous islands and islets with great heterogeneity in topographic, geological, historical and environmental properties, offers an ideal natural laboratory for ecological and evolutionary research, and has been the stage for a very long interaction between human civilizations and local ecosystems. This work presents insights that have been gained from past and current relevant research in the area, highlighting also the importance of the Aegean archipelago as a useful model to address many major questions in biogeography, ecology and evolutionary processes. Among the most interesting findings from such studies concern the role of habitat heterogeneity as the most important determinant of species richness, the development of a new model (Choros) for the species–area–habitats relationship, the mechanistic aspects of the Small Island Effect, the very high rates of species turnover, the lack of a role for interspecific competition in shaping species co-occurrence patterns in most cases, the importance of non adaptive radiation in diversification of several taxa, the insights into the relative roles of vicariance and dispersal in speciation, the understanding of the interplay between human presence and the establishment of exotic species and extinction of indigenous biotas. Concluding, the Aegean archipelago is an ideal stage for research in evolution, ecology and biogeography, and has the potential to become a model study area at a global level, especially for land-bridge, continental islands.
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Affiliation(s)
- Spyros Sfenthourakis
- Department of Biological Sciences, University of Cyprus, Panepistimiou 1, 2109 Aglantzia, Nicosia, Cyprus
| | - Kostas A Triantis
- Department of Ecology and Taxonomy, Faculty of Biology, National and Kapodistrian University, Athens, Greece
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15
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The Mouse-colored Tyrannulet (Phaeomyias murina) is a species complex that includes the Cocos Flycatcher (Nesotriccus ridgwayi), an island form that underwent a population bottleneck. Mol Phylogenet Evol 2016; 101:294-302. [DOI: 10.1016/j.ympev.2016.04.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 04/19/2016] [Accepted: 04/24/2016] [Indexed: 11/22/2022]
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16
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Thomé MTC, Carstens BC. Phylogeographic model selection leads to insight into the evolutionary history of four-eyed frogs. Proc Natl Acad Sci U S A 2016; 113:8010-7. [PMID: 27432969 PMCID: PMC4961127 DOI: 10.1073/pnas.1601064113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Phylogeographic research investigates biodiversity at the interface between populations and species, in a temporal and geographic context. Phylogeography has benefited from analytical approaches that allow empiricists to estimate parameters of interest from the genetic data (e.g., θ = 4Neμ, population divergence, gene flow), and the widespread availability of genomic data allow such parameters to be estimated with greater precision. However, the actual inferences made by phylogeographers remain dependent on qualitative interpretations derived from these parameters' values and as such may be subject to overinterpretation and confirmation bias. Here we argue in favor of using an objective approach to phylogeographic inference that proceeds by calculating the probability of multiple demographic models given the data and the subsequent ranking of these models using information theory. We illustrate this approach by investigating the diversification of two sister species of four-eyed frogs of northeastern Brazil using single nucleotide polymorphisms obtained via restriction-associated digest sequencing. We estimate the composite likelihood of the observed data given nine demographic models and then rank these models using Akaike information criterion. We demonstrate that estimating parameters under a model that is a poor fit to the data is likely to produce values that lead to spurious phylogeographic inferences. Our results strongly imply that identifying which parameters to estimate from a given system is a key step in the process of phylogeographic inference and is at least as important as being able to generate precise estimates of these parameters. They also illustrate that the incorporation of model uncertainty should be a component of phylogeographic hypothesis tests.
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Affiliation(s)
- Maria Tereza C Thomé
- Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Campus Rio Claro, 13506900 Rio Claro, SP, Brazil
| | - Bryan C Carstens
- Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus, OH 43210
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17
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Allen SJ, Bryant KA, Kraus RHS, Loneragan NR, Kopps AM, Brown AM, Gerber L, Krützen M. Genetic isolation between coastal and fishery-impacted, offshore bottlenose dolphin (Tursiopsspp.) populations. Mol Ecol 2016; 25:2735-53. [DOI: 10.1111/mec.13622] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Revised: 02/17/2016] [Accepted: 03/11/2016] [Indexed: 11/29/2022]
Affiliation(s)
- Simon J. Allen
- Cetacean Research Unit; School of Veterinary and Life Sciences; Murdoch University; Perth Western Australia 6150 Australia
- Centre for Marine Futures; School of Animal Biology and Oceans Institute; University of Western Australia; Perth Western Australia 6009 Australia
| | - Kate A. Bryant
- School of Veterinary and Life Sciences; Murdoch University; Murdoch Western Australia 6150 Australia
| | - Robert H. S. Kraus
- Department of Biology; University of Konstanz; 78457 Konstanz Germany
- Department of Migration and Immuno-Ecology; Max Planck Institute for Ornithology; Am Obstberg 1 78315 Radolfzell Germany
| | - Neil R. Loneragan
- School of Veterinary and Life Sciences; Murdoch University; Murdoch Western Australia 6150 Australia
| | - Anna M. Kopps
- Evolutionary Genetics Group; Department of Anthropology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
- Evolution and Ecology Research Centre; School of Biological; Earth and Environmental Sciences; University of New South Wales; Sydney New South Wales 2052 Australia
| | - Alexander M. Brown
- Cetacean Research Unit; School of Veterinary and Life Sciences; Murdoch University; Perth Western Australia 6150 Australia
| | - Livia Gerber
- Evolutionary Genetics Group; Department of Anthropology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
| | - Michael Krützen
- Evolutionary Genetics Group; Department of Anthropology; University of Zurich; Winterthurerstrasse 190 8057 Zurich Switzerland
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18
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Runemark A, Sagonas K, Svensson EI. Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard. Ecology 2015; 96:2077-92. [DOI: 10.1890/14-1996.1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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19
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Nichols P, Genner MJ, van Oosterhout C, Smith A, Parsons P, Sungani H, Swanstrom J, Joyce DA. Secondary contact seeds phenotypic novelty in cichlid fishes. Proc Biol Sci 2015; 282:20142272. [PMID: 25392475 PMCID: PMC4262179 DOI: 10.1098/rspb.2014.2272] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Theory proposes that genomic admixture between formerly reproductively isolated populations can generate phenotypic novelty for selection to act upon. Secondary contact may therefore be a significant promoter of phenotypic novelty that allows species to overcome environmental challenges and adapt to novel environments, including during adaptive radiation. To date, this has largely been considered from the perspective of interspecific hybridization at contact zones. However, it is also possible that this process occurs more commonly between natural populations of a single species, and thus its importance in adaptive evolution may have been underestimated. In this study, we tested the consequences of genomic introgression during apparent secondary contact between phenotypically similar lineages of the riverine cichlid fish Astatotilapia calliptera. We provide population genetic evidence of a secondary contact zone in the wild, and then demonstrate using mate-choice experiments that both lineages can reproduce together successfully in laboratory conditions. Finally, we show that genomically admixed individuals display extreme phenotypes not observed in the parental lineages. Collectively, the evidence shows that secondary contact can drive the evolution of phenotypic novelty, suggesting that pulses of secondary contact may repeatedly seed genetic novelty, which when coupled with ecological opportunity could promote rapid adaptive evolution in natural circumstances.
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Affiliation(s)
- Paul Nichols
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK
| | - Martin J Genner
- School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Cock van Oosterhout
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK School of Environmental Science, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, UK
| | - Alan Smith
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK
| | - Paul Parsons
- School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Harold Sungani
- School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Jennifer Swanstrom
- School of Biological Sciences, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Domino A Joyce
- School of Biological, Biomedical and Environmental Sciences, University of Hull, Hull HU6 7RX, UK
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20
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Kurita K, Hikida T, Toda M. An investigation for population maintenance mechanism in a miniature garden: genetic connectivity or independence of small islet populations of the Ryukyu five-lined skink. J Hered 2014; 105:773-83. [PMID: 25189776 DOI: 10.1093/jhered/esu055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The Ryukyu five-lined skink (Plestiodon marginatus) is an island lizard that is even found in tiny islets with less than half a hectare of habitat area. We hypothesized that the island populations are maintained under frequent gene flow among the islands or independent of each other. To test our hypotheses, we investigated genetic structure of 21 populations from 11 land-bridge islands that were connected during the latest glacial age, and 4 isolated islands. Analyses using mitochondrial cytochrome b gene sequence (n = 67) and 10 microsatellite loci (n = 235) revealed moderate to high levels of genetic differentiation, existence of many private alleles/haplotypes in most islands, little contemporary migration, a positive correlation between genetic variability and island area, and a negative correlation between relatedness and island area. These evidences suggest a strong effect of independent genetic drift as opposed to gene flow, favoring the isolation hypothesis even in tiny islet populations. Isolation-by-distance effect was demonstrated and it became more prominent when the 4 isolated islands were excluded, suggesting that the pattern is a remnant of the land-bridge age. In a few island populations, however, the possibility of occasional overwater dispersals was partially supported and therefore could not be ruled out.
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Affiliation(s)
- Kazuki Kurita
- From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda).
| | - Tsutomu Hikida
- From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda)
| | - Mamoru Toda
- From the Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto, 606-8502, Japan (Kurita and Hikida) and Tropical Biosphere Research Center, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan (Toda)
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21
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Zarowiecki M, Linton YM, Post RJ, Bangs MJ, Htun PT, Hlaing T, Seng CM, Baimai V, Ding TH, Sochantha T, Walton C. Repeated landmass reformation limits diversification in the widespread littoral zone mosquito Anopheles sundaicus sensu lato in the Indo-Oriental Region. Mol Ecol 2014; 23:2573-89. [PMID: 24750501 DOI: 10.1111/mec.12761] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 04/14/2014] [Accepted: 04/16/2014] [Indexed: 11/29/2022]
Abstract
Southeast Asia harbours abundant biodiversity, hypothesized to have been generated by Pliocene and Pleistocene climatic and environmental change. Vicariance between the island of Borneo, the remaining Indonesian archipelago and mainland Southeast Asia caused by elevated sea levels during interglacial periods has been proposed to lead to diversification in the littoral zone mosquito Anopheles (Cellia) sundaicus (Rodenwaldt) sensu lato. To test this biogeographical hypothesis, we inferred the population history and assessed gene flow of A. sundaicus s.l. sampled from 18 populations across its pan-Asian species range, using sequences from mitochondrial cytochrome c oxidase subunit 1 (CO1), the internal transcribed spacer 2 (ITS2) and the mannose phosphate isomerase (Mpi) gene. A hypothesis of ecological speciation for A. sundaicus involving divergent adaptation to brackish and freshwater larval habitats was also previously proposed, based on a deficiency of heterozygotes for Mpi allozyme alleles in sympatry. This hypothesis was not supported by Mpi sequence data, which exhibited no fixed differences between brackish and freshwater larval habitats. Mpi and CO1 supported the presence of up to eight genetically distinct population groupings. Counter to the hypothesis of three allopatric species, divergence was often no greater between Borneo, Sumatra/Java and the Southeast Asian mainland than it was between genetic groupings within these landmasses. An isolation-with-migration (IM) model indicates recurrent gene flow between the current major landmasses. Such gene flow would have been possible during glacial periods when the current landmasses merged, presenting opportunities for dispersal along expanding and contracting coastlines. Consequently, Pleistocene climatic variation has proved a homogenizing, rather than diversifying, force for A. sundaicus diversity.
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Affiliation(s)
- Magdalena Zarowiecki
- Parasite Genomics Group, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
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22
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Cruickshank TE, Hahn MW. Reanalysis suggests that genomic islands of speciation are due to reduced diversity, not reduced gene flow. Mol Ecol 2014; 23:3133-57. [DOI: 10.1111/mec.12796] [Citation(s) in RCA: 764] [Impact Index Per Article: 76.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 05/05/2014] [Accepted: 05/07/2014] [Indexed: 12/18/2022]
Affiliation(s)
| | - Matthew W. Hahn
- Department of Biology; Indiana University; Bloomington IN 47405 USA
- School of Informatics and Computing; Indiana University; Bloomington IN 47405 USA
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23
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Runemark A, Brydegaard M, Svensson EI. Does relaxed predation drive phenotypic divergence among insular populations? J Evol Biol 2014; 27:1676-90. [PMID: 24890841 DOI: 10.1111/jeb.12421] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 04/21/2014] [Accepted: 04/28/2014] [Indexed: 11/28/2022]
Abstract
The evolution of striking phenotypes on islands is a well-known phenomenon, and there has been a long-standing debate on the patterns of body size evolution on islands. The ecological causes driving divergence in insular populations are, however, poorly understood. Reduced predator fauna is expected to lower escape propensity, increase body size and relax selection for crypsis in small-bodied, insular prey species. Here, we investigated whether escape behaviour, body size and dorsal coloration have diverged as predicted under predation release in spatially replicated islet and mainland populations of the lizard species Podarcis gaigeae. We show that islet lizards escape approaching observers at shorter distances and are larger than mainland lizards. Additionally, we found evidence for larger between-population variation in body size among the islet populations than mainland populations. Moreover, islet populations are significantly more divergent in dorsal coloration and match their respective habitats poorer than mainland lizards. These results strongly suggest that predation release on islets has driven population divergence in phenotypic and behavioural traits and that selective release has affected both trait means and variances. Relaxed predation pressure is therefore likely to be one of the major ecological factors driving body size divergence on these islands.
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Affiliation(s)
- A Runemark
- Evolutionary Ecology Unit, Department of Biology, Lund University, Lund, Sweden
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24
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Mitochondrial and nuclear DNA survey of Zootoca vivipara across the eastern Italian Alps: evolutionary relationships, historical demography and conservation implications. PLoS One 2014; 9:e85912. [PMID: 24465784 PMCID: PMC3895026 DOI: 10.1371/journal.pone.0085912] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022] Open
Abstract
The European common lizard Zootoca vivipara exhibits reproductive bimodality, with populations being either viviparous or oviparous. In the central-eastern Italian Alps oviparous populations (Z. v. carniolica) and viviparous populations (Z. v. vivipara) partly overlap geographically. Studying the evolutionary relationship between these taxa presents an interesting opportunity to gain insight into the evolution of this trait. We aim to: i) test whether Z. v. carniolica, which is endangered, constitutes an ESU (Evolutionary Significant Unity); ii) infer mtDNA divergence time between the Z. v. carniolica clade and all the other Z. vivipara subspecies with the aid of an external calibration point; and iii) describe the phylogeographical and demographic scenarios in the area. To do so we sequenced about 200 individuals for mitochondrial variation; 64 of them were also analysed for three nuclear genes. Furthermore, we analysed the same nuclear markers in 17 individuals from the other oviparous subspecies Z. v. louislantzi and 11 individuals of Z. v. vivipara from widespread geographical origins. The mtDNA and nDNA loci that we examined supported the monophyly of Z. v. carniolica. The mtDNA-based estimate of divergence time between Z. v. carniolica and all the other subspecies indicated a separation at 4.5 Mya (95% CI 6.1–2.6), with about 5% of sequence divergence. Considering that Z. v. carniolica harbours higher genetic diversity, while Z. v. vivipara from central-eastern Alps shows a signature of recent population and spatial expansion, we argue that Z. v. carniolica represents a distinct evolutionary unit, with a presumably long-term evolutionary history of separation. Z. v. carniolica populations, occurring at higher latitudes and altitudes than insofar supposed, live in peat bogs, a seriously threatened habitat: taking into account also its evolutionary distinctness, specific conservation measures should be considered.
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25
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Burridge CP, Brown WE, Wadley J, Nankervis DL, Olivier L, Gardner MG, Hull C, Barbour R, Austin JJ. Did postglacial sea-level changes initiate the evolutionary divergence of a Tasmanian endemic raptor from its mainland relative? Proc Biol Sci 2013; 280:20132448. [PMID: 24174114 DOI: 10.1098/rspb.2013.2448] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Populations on continental islands are often distinguishable from mainland conspecifics with respect to body size, appearance, behaviour or life history, and this is often congruent with genetic patterns. It is commonly assumed that such differences developed following the complete isolation of populations by sea-level rise following the Last Glacial Maximum (LGM). However, population divergence may predate the LGM, or marine dispersal and colonization of islands may have occurred more recently; in both cases, populations may have also diverged despite ongoing gene flow. Here, we test these alternative hypotheses for the divergence between wedge-tailed eagles from mainland Australia (Aquila audax audax) and the threatened Tasmanian subspecies (Aquila audax fleayi), based on variation at 20 microsatellite loci and mtDNA. Coalescent analyses indicate that population divergence appreciably postdates the severance of terrestrial habitat continuity and occurred without any subsequent gene flow. We infer a recent colonization of Tasmania by marine dispersal and cannot discount founder effects as the cause of differences in body size and life history. We call into question the general assumption of post-LGM marine transgression as the initiator of divergence of terrestrial lineages on continental islands and adjacent mainland, and highlight the range of alternative scenarios that should be considered.
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Affiliation(s)
- C P Burridge
- School of Zoology, University of Tasmania, , Hobart, Tasmania 7001, Australia, Department of Primary Industry, Parks, Water and Environment, , Hobart, Tasmania 7001, Australia, Australian Centre for Ancient DNA, School of Earth and Environmental Sciences and Environment Institute, University of Adelaide, , North Terrace, Adelaide, South Australia 5005, Australia, School of Biological Sciences, Flinders University, , GPO Box 2100, Adelaide, South Australia 5001, Australia, Evolutionary Biology Unit, South Australian Museum, , North Terrace, Adelaide, South Australia 5001, Australia, Hydro Tasmania, , GPO Box 355, Hobart 7001, Australia, Sciences Department, Museum Victoria, , Carlton Gardens, Melbourne, Victoria 3001, Australia
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26
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Runemark A, Hansson B, Ljungqvist M, Brydegaard M, Svensson EI. Has the inbreeding load for a condition-dependent sexual signalling trait been purged in insular lizard populations? Mol Ecol 2013; 22:1310-21. [PMID: 23294127 DOI: 10.1111/mec.12178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 11/16/2012] [Accepted: 11/21/2012] [Indexed: 11/30/2022]
Abstract
Sexually selected traits are often condition-dependent and are expected to be affected by genome-wide distributed deleterious mutations and inbreeding. However, sexual selection is a powerful selective force that can counteract inbreeding through purging of deleterious mutations. Inbreeding and purging of the inbreeding load for sexually selected traits has rarely been studied across natural populations with different degrees of inbreeding. Here we investigate inbreeding effects (measured as marker-based heterozygosity) on condition-dependent sexually selected signalling trait and other morphological traits across islet- and mainland populations (n = 15) of an endemic lizard species (Podarcis gaigeae). Our data suggest inbreeding depression on a condition-dependent sexually selected signalling character among mainland subpopulations with low or intermediate levels of inbreeding, but no sign of inbreeding depression among small and isolated islet populations despite their higher overall inbreeding levels. In contrast, there was no such pattern among ten other morphological traits which are primarily naturally selected and presumably not involved in sexual signalling. These results are in line with purging of recessive deleterious alleles, or purging in combination with stochastic fixation of alleles by genetic drift, for a sexual signalling character in the islet environment, which is characterized by low population sizes and strong sexual selection. Higher clutch sizes in islet populations also raise interesting questions regarding the possibility of antagonistic pleiotropy. Purging and other non-exclusive explanations of our results are discussed.
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Affiliation(s)
- Anna Runemark
- Department of Biology, Lund University, Lund, Sweden.
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Moodley Y, Linz B, Bond RP, Nieuwoudt M, Soodyall H, Schlebusch CM, Bernhöft S, Hale J, Suerbaum S, Mugisha L, van der Merwe SW, Achtman M. Age of the association between Helicobacter pylori and man. PLoS Pathog 2012; 8:e1002693. [PMID: 22589724 PMCID: PMC3349757 DOI: 10.1371/journal.ppat.1002693] [Citation(s) in RCA: 211] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 03/27/2012] [Indexed: 02/07/2023] Open
Abstract
When modern humans left Africa ca. 60,000 years ago (60 kya), they were already infected with Helicobacter pylori, and these bacteria have subsequently diversified in parallel with their human hosts. But how long were humans infected by H. pylori prior to the out-of-Africa event? Did this co-evolution predate the emergence of modern humans, spanning the species divide? To answer these questions, we investigated the diversity of H. pylori in Africa, where both humans and H. pylori originated. Three distinct H. pylori populations are native to Africa: hpNEAfrica in Afro-Asiatic and Nilo-Saharan speakers, hpAfrica1 in Niger-Congo speakers and hpAfrica2 in South Africa. Rather than representing a sustained co-evolution over millions of years, we find that the coalescent for all H. pylori plus its closest relative H. acinonychis dates to 88–116 kya. At that time the phylogeny split into two primary super-lineages, one of which is associated with the former hunter-gatherers in southern Africa known as the San. H. acinonychis, which infects large felines, resulted from a later host jump from the San, 43–56 kya. These dating estimates, together with striking phylogenetic and quantitative human-bacterial similarities show that H. pylori is approximately as old as are anatomically modern humans. They also suggest that H. pylori may have been acquired via a single host jump from an unknown, non-human host. We also find evidence for a second Out of Africa migration in the last 52,000 years, because hpEurope is a hybrid population between hpAsia2 and hpNEAfrica, the latter of which arose in northeast Africa 36–52 kya, after the Out of Africa migrations around 60 kya. We previously showed that the population history of H. pylori may be used as a marker for human migrations, including the demonstration that humans carried H. pylori out of Africa 60,000 years ago during their recent global expansions. But how long were humans infected by H. pylori prior to the out-of-Africa event? Here we showed that chimpanzees in Central-East Africa do not possess Helicobacter-like bacteria, as would have been expected for pathogen-host co-evolution over millions of years. Using H. pylori gene sequences isolated from San, a group of click-speaking hunter-gatherers, and numerous other sources, we calculated that humans have been infected with H. pylori for at least 88,000–116,000 years. Phylogenetic comparisons showed similar evolutionary histories for human and H. pylori lineages and suggest that this association stemmed from a single host jump. We showed that hpAfrica2, the most divergent H. pylori population, arose in the San and that their progenitors were the source of H. acinonychis which was acquired by large felines approximately 50,000 years ago. Furthermore, our data provided clear evidence for a recent second exodus Out of Africa in the last 52,000 years which was essential for the formation of the hybrid population that currently infects Europeans.
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Affiliation(s)
- Yoshan Moodley
- Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Berlin, Germany
- Konrad Lorenz Institute for Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Vienna, Austria
- * E-mail: (YM); (BL); (MA)
| | - Bodo Linz
- Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Berlin, Germany
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail: (YM); (BL); (MA)
| | - Robert P. Bond
- Hepatology and GI-Research Laboratory, Department of Immunology, University of Pretoria, Pretoria, South Africa
| | - Martin Nieuwoudt
- Hepatology and GI-Research Laboratory, Department of Immunology, University of Pretoria, Pretoria, South Africa
| | - Himla Soodyall
- Human Genomic Diversity and Disease Research Unit, Division of Human Genetics, School of Pathology, University of the Witwatersrand/National Health Laboratory Services, Johannesburg, South Africa
| | - Carina M. Schlebusch
- Human Genomic Diversity and Disease Research Unit, Division of Human Genetics, School of Pathology, University of the Witwatersrand/National Health Laboratory Services, Johannesburg, South Africa
| | - Steffi Bernhöft
- Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Berlin, Germany
| | - James Hale
- Environmental Research Institute and Department of Microbiology, University College Cork, Cork, Ireland
| | - Sebastian Suerbaum
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School, Hannover, Germany
| | | | - Schalk W. van der Merwe
- Hepatology and GI-Research Laboratory, Department of Immunology, University of Pretoria, Pretoria, South Africa
| | - Mark Achtman
- Max-Planck-Institut für Infektionsbiologie, Department of Molecular Biology, Berlin, Germany
- Environmental Research Institute and Department of Microbiology, University College Cork, Cork, Ireland
- * E-mail: (YM); (BL); (MA)
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RUNEMARK ANNA, SVENSSON ERIKI. Sexual selection as a promoter of population divergence in male phenotypic characters: a study on mainland and islet lizard populations. Biol J Linn Soc Lond 2012. [DOI: 10.1111/j.1095-8312.2012.01866.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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