1
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Franco FF, Amaral DT, Bonatelli IAS, Meek JB, Moraes EM, Zappi DC, Taylor NP, Eaton DAR. A historical stepping-stone path for an island-colonizing cactus across a submerged "bridge" archipelago. Heredity (Edinb) 2024; 132:296-308. [PMID: 38637723 PMCID: PMC11166651 DOI: 10.1038/s41437-024-00683-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 03/26/2024] [Accepted: 03/27/2024] [Indexed: 04/20/2024] Open
Abstract
Here we use population genomic data (ddRAD-Seq) and ecological niche modeling to test biogeographic hypotheses for the divergence of the island-endemic cactus species Cereus insularis Hemsl. (Cereeae; Cactaceae) from its sister species C. fernambucensis Lem. The Cereus insularis grows in the Fernando de Noronha Islands (FNI), a Neotropical archipelago located 350 km off the Brazilian Atlantic Forest (BAF) coast. Phylogeographic reconstructions support a northward expansion by the common ancestor of C. insularis and C. fernambucensis along the mainland BAF coast, with C. insularis diverging from the widespread mainland taxon C. fernambucensis after colonizing FNI in the late Pleistocene. The morphologically distinct C. insularis is monophyletic and nested within C. fernambucensis, as expected from a progenitor-derivative speciation model. We tested alternative biogeographic and demographic hypotheses for the colonization of the FNI using Approximate Bayesian Computation. We found the greatest support for a stepping-stone path that emerged during periods of decreased sea level (the "bridge" hypothesis), in congruence with historical ecological niche modeling that shows highly suitable habitats on stepping-stone islands during glacial periods. The outlier analyses reveal signatures of selection in C. insularis, suggesting a putative role of adaptation driving rapid anagenic differentiation of this species in FNI.
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Affiliation(s)
- Fernando Faria Franco
- Departamento de Biologia. Centro de Ciências Humanas e Biológicas, Universidade Federal de São Carlos (UFSCar), Sorocaba, Brazil.
| | - Danilo Trabuco Amaral
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil
- Programa de Pós Graduação em Biologia Comparada. Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), Ribeirão Preto, Brazil
| | - Isabel A S Bonatelli
- Instituto de Ciências Ambientais, Químicas e Farmacêuticas. Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Paulo, Diadema, SP, Brazil
| | - Jared B Meek
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, 10027, USA
| | - Evandro Marsola Moraes
- Departamento de Biologia. Centro de Ciências Humanas e Biológicas, Universidade Federal de São Carlos (UFSCar), Sorocaba, Brazil
| | - Daniela Cristina Zappi
- Programa de Pós Graduação em Botânica, Instituto de Ciências Biológicas, Universidade de Brasília, PO Box 04457, Brasília, DF, 70910970, Brazil
| | - Nigel Paul Taylor
- Departamento de Biologia. Centro de Ciências Humanas e Biológicas, Universidade Federal de São Carlos (UFSCar), Sorocaba, Brazil
| | - Deren A R Eaton
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, 10027, USA
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2
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Nosil P, Gompert Z, Funk DJ. Divergent dynamics of sexual and habitat isolation at the transition between stick insect populations and species. Nat Commun 2024; 15:2273. [PMID: 38480699 PMCID: PMC10937975 DOI: 10.1038/s41467-024-46294-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 02/22/2024] [Indexed: 03/17/2024] Open
Abstract
Speciation is often viewed as a continuum along which populations diverge until they become reproductively-isolated species. However, such divergence may be heterogeneous, proceeding in fits and bursts, rather than being uniform and gradual. We show in Timema stick insects that one component of reproductive isolation evolves non-uniformly across this continuum, whereas another does not. Specifically, we use thousands of host-preference and mating trials to study habitat and sexual isolation among 42 pairs of taxa spanning a range of genomic differentiation and divergence time. We find that habitat isolation is uncoupled from genomic differentiation within species, but accumulates linearly with it between species. In contrast, sexual isolation accumulates linearly across the speciation continuum, and thus exhibits similar dynamics to morphological traits not implicated in reproductive isolation. The results show different evolutionary dynamics for different components of reproductive isolation and highlight a special relevance for species status in the process of speciation.
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Affiliation(s)
- Patrik Nosil
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
| | | | - Daniel J Funk
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA.
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3
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Ålund M, Cenzer M, Bierne N, Boughman JW, Cerca J, Comerford MS, Culicchi A, Langerhans B, McFarlane SE, Möst MH, North H, Qvarnström A, Ravinet M, Svanbäck R, Taylor SA. Anthropogenic Change and the Process of Speciation. Cold Spring Harb Perspect Biol 2023; 15:a041455. [PMID: 37788888 PMCID: PMC10691492 DOI: 10.1101/cshperspect.a041455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Anthropogenic impacts on the environment alter speciation processes by affecting both geographical contexts and selection patterns on a worldwide scale. Here we review evidence of these effects. We find that human activities often generate spatial isolation between populations and thereby promote genetic divergence but also frequently cause sudden secondary contact and hybridization between diverging lineages. Human-caused environmental changes produce new ecological niches, altering selection in diverse ways that can drive diversification; but changes also often remove niches and cause extirpations. Human impacts that alter selection regimes are widespread and strong in magnitude, ranging from local changes in biotic and abiotic conditions to direct harvesting to global climate change. Altered selection, and evolutionary responses to it, impacts early-stage divergence of lineages, but does not necessarily lead toward speciation and persistence of separate species. Altogether, humans both promote and hinder speciation, although new species would form very slowly relative to anthropogenic hybridization, which can be nearly instantaneous. Speculating about the future of speciation, we highlight two key conclusions: (1) Humans will have a large influence on extinction and "despeciation" dynamics in the short term and on early-stage lineage divergence, and thus potentially speciation in the longer term, and (2) long-term monitoring combined with easily dated anthropogenic changes will improve our understanding of the processes of speciation. We can use this knowledge to preserve and restore ecosystems in ways that promote (re-)diversification, increasing future opportunities of speciation and enhancing biodiversity.
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Affiliation(s)
- Murielle Ålund
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Meredith Cenzer
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA
| | - Nicolas Bierne
- ISEM, Université de Montpellier, CNRS, IRD, Montpellier 34095, France
| | - Janette W Boughman
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan 48824, USA
| | - José Cerca
- CEES - Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, Oslo 0316, Norway
| | | | - Alessandro Culicchi
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Brian Langerhans
- Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - S Eryn McFarlane
- Department of Botany, University of Wyoming, Laramie, Wyoming 82071, USA
- Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada
| | - Markus H Möst
- Research Department for Limnology, University of Innsbruck, Innsbruck 6020, Austria
| | - Henry North
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
| | - Anna Qvarnström
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Mark Ravinet
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - Richard Svanbäck
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala 75236, Sweden
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, Colorado 80309, USA
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4
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Giesen A, Blanckenhorn WU, Schäfer MA, Shimizu KK, Shimizu-Inatsugi R, Misof B, Podsiadlowski L, Niehuis O, Lischer HEL, Aeschbacher S, Kapun M. Geographic Variation in Genomic Signals of Admixture Between Two Closely Related European Sepsid Fly Species. Evol Biol 2023; 50:395-412. [PMID: 37854269 PMCID: PMC10579158 DOI: 10.1007/s11692-023-09612-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 07/28/2023] [Indexed: 10/20/2023]
Abstract
The extent of interspecific gene flow and its consequences for the initiation, maintenance, and breakdown of species barriers in natural systems remain poorly understood. Interspecific gene flow by hybridization may weaken adaptive divergence, but can be overcome by selection against hybrids, which may ultimately promote reinforcement. An informative step towards understanding the role of gene flow during speciation is to describe patterns of past gene flow among extant species. We investigate signals of admixture between allopatric and sympatric populations of the two closely related European dung fly species Sepsis cynipsea and S. neocynipsea (Diptera: Sepsidae). Based on microsatellite genotypes, we first inferred a baseline demographic history using Approximate Bayesian Computation. We then used genomic data from pooled DNA of natural and laboratory populations to test for past interspecific gene flow based on allelic configurations discordant with the inferred population tree (ABBA-BABA test with D-statistic). Comparing the detected signals of gene flow with the contemporary geographic relationship among interspecific pairs of populations (sympatric vs. allopatric), we made two contrasting observations. At one site in the French Cevennes, we detected an excess of past interspecific gene flow, while at two sites in Switzerland we observed lower signals of past microsatellite genotypes gene flow among populations in sympatry compared to allopatric populations. These results suggest that the species boundaries between these two species depend on the past and/or present eco-geographic context in Europe, which indicates that there is no uniform link between contemporary geographic proximity and past interspecific gene flow in natural populations. Supplementary Information The online version contains supplementary material available at 10.1007/s11692-023-09612-5.
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Affiliation(s)
- Athene Giesen
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Wolf U. Blanckenhorn
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Martin A. Schäfer
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Kentaro K. Shimizu
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Rie Shimizu-Inatsugi
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Bernhard Misof
- Zoological Research Museum Alexander Koenig, Bonn, Germany
| | | | - Oliver Niehuis
- Department of Evolutionary Biology and Ecology, Institute of Biology I (Zoology), Albert Ludwig University, Freiburg, Germany
| | - Heidi E. L. Lischer
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Interfaculty Bioinformatics Unit, University of Bern, Bern, Switzerland
| | - Simon Aeschbacher
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Martin Kapun
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
- Division of Cell & Developmental Biology, Medical University of Vienna, Vienna, Austria
- Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria
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5
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Zamorano LS, Gompert Z, Fronhofer EA, Feder JL, Nosil P. A stabilizing eco-evolutionary feedback loop in the wild. Curr Biol 2023; 33:3272-3278.e3. [PMID: 37478865 DOI: 10.1016/j.cub.2023.06.056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 04/24/2023] [Accepted: 06/21/2023] [Indexed: 07/23/2023]
Abstract
There is increasing evidence that evolutionary and ecological processes can operate on the same timescale1,2 (i.e., contemporary time). As such, evolution can be sufficiently rapid to affect ecological processes such as predation or competition. Thus, evolution can influence population, community, and ecosystem-level dynamics. Indeed, studies have now shown that evolutionary dynamics can alter community structure3,4,5,6 and ecosystem function.7,8,9,10 In turn, shifts in ecological dynamics driven by evolution might feed back to affect the evolutionary trajectory of individual species.11 This feedback loop, where evolutionary and ecological changes reciprocally affect one another, is a central tenet of eco-evolutionary dynamics.1,12 However, most work on such dynamics in natural populations has focused on one-way causal associations between ecology and evolution.13 Hence, direct empirical evidence for eco-evolutionary feedback is rare and limited to laboratory or mesocosm experiments.13,14,15,16 Here, we show in the wild that eco-evolutionary dynamics in a plant-feeding arthropod community involve a negative feedback loop. Specifically, adaptation in cryptic coloration in a stick-insect species mediates bird predation, with local maladaptation increasing predation. In turn, the abundance of arthropods is reduced by predation. Here, we experimentally manipulate arthropod abundance to show that these changes at the community level feed back to affect the stick-insect evolution. Specifically, low-arthropod abundance increases the strength of selection on crypsis, increasing local adaptation of stick insects in a negative feedback loop. Our results suggest that eco-evolutionary feedbacks are able to stabilize complex systems by preventing consistent directional change and therefore increasing resilience.
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Affiliation(s)
- Laura S Zamorano
- Theoretical and Experimental Ecology (SETE), CNRS, 2 route du CNRS, 09200 Moulis, France; CEFE, Université de Montpellier, CNRS, EPHE, IRD, Université Paul Valéry Montpellier 3, 34095 Montpellier, France; ISEM, CNRS, IRD, EPHE, Université de Montpellier, 34095 Montpellier, France.
| | | | | | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, South Bend, IN 46556, USA
| | - Patrik Nosil
- Theoretical and Experimental Ecology (SETE), CNRS, 2 route du CNRS, 09200 Moulis, France; CEFE, Université de Montpellier, CNRS, EPHE, IRD, Université Paul Valéry Montpellier 3, 34095 Montpellier, France.
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6
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Galvez JR, St John ME, McLean K, Touokong CD, Gonwouo LN, Martin CH. Trophic specialization on unique resources despite limited niche divergence in a celebrated example of sympatric speciation. ECOLOGY OF FRESHWATER FISH 2022; 31:675-692. [PMID: 36211622 PMCID: PMC9542214 DOI: 10.1111/eff.12661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 04/02/2022] [Indexed: 06/16/2023]
Abstract
Trophic niche partitioning is observed in many adaptive radiations and is hypothesized to be a central process underlying species divergence. However, patterns of dietary niche partitioning are inconsistent across radiations and there are few studies of niche partitioning in putative examples of sympatric speciation. Here, we conducted the first quantitative study of dietary niche partitioning using stomach contents and stable isotope analyses in one of the most celebrated examples of sympatric speciation: the cichlid radiation from crater lake Barombi Mbo, Cameroon. We found little evidence for trophic niche partitioning among cichlids, including the nine species coexisting in the narrow littoral zone. Stable isotope analyses supported these conclusions of substantial dietary overlap. Our data, however, did reveal that five of eleven species consume rare dietary items, including freshwater sponge, terrestrial ants, and nocturnal foraging on shrimp. Stomach contents of the spongivore (Pungu maclareni) were 20% freshwater sponge, notable considering that only 0.04% of all fishes consume sponges. Overall, we conclude that cichlid species in lake Barombi Mbo overlap considerably in broad dietary niches-in part due to the large proportion of detritus in the stomach contents of all species-but there is evidence for divergence among species in their diet specializations on unique resources. We speculate that these species may utilize these additional specialized resources during periods of low resource abundance in support of Liem's paradox.
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Affiliation(s)
- Jacquelyn R Galvez
- Department of Integrative Biology, University of California, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
| | - Michelle E St John
- Department of Integrative Biology, University of California, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
| | - Keara McLean
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Legrand Nono Gonwouo
- Laboratory of Zoology, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon
| | - Christopher H Martin
- Department of Integrative Biology, University of California, Berkeley, CA, USA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA
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7
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Jahnke M, Moknes P, Le Moan A, Martens GA, Jonsson PR. Seascape genomics identify adaptive barriers correlated to tidal amplitude in the shore crab Carcinus maenas. Mol Ecol 2022; 31:1980-1994. [PMID: 35080070 PMCID: PMC9540756 DOI: 10.1111/mec.16371] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 01/15/2022] [Accepted: 01/18/2022] [Indexed: 11/27/2022]
Abstract
Most marine invertebrates disperse during a planktonic larval stage that may drift for weeks with ocean currents. A challenge for larvae of coastal species is to return to coastal nursery habitats. Shore crab (Carcinus maenas L.) larvae are known to show tidal rhythmicity in vertical migration in tidal areas and circadian rhythmicity in microtidal areas, which seems to increase successful coastal settlement. We studied genome-wide differentiation based on 24,000 single nucleotide polymorphisms of 12 native populations of shore crab sampled from a large tidal amplitude gradient from macrotidal (~8 m) to microtidal (~0.2 m). Dispersal and recruitment success of larvae was assessed with a Lagrangian biophysical model, which showed a strong effect of larval behaviour on long-term connectivity, and dispersal barriers that partly coincided with different tidal environments. The genetic population structure showed a subdivision of the samples into three clusters, which represent micro-, meso- and macrotidal areas. The genetic differentiation was mostly driven by 0.5% outlier loci, which showed strong allelic clines located at the limits between the three tidal areas. Demographic modelling suggested that the two genetic barriers have different origins. Differential gene expression of two clock genes (cyc and pdp1) further highlighted phenotypic differences among genetic clusters that are potentially linked to the differences in larval behaviour. Taken together, our seascape genomic study suggests that tidal regime acts as a strong selection force on shore crab population structure, consistent with larval behaviour affecting dispersal and recruitment success.
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Affiliation(s)
- Marlene Jahnke
- Department of Marine SciencesTjärnö Marine LaboratoryUniversity of GothenburgStrömstadSweden
| | - Per‐Olav Moknes
- Department of Marine ScienceUniversity of GothenburgGothenburgSweden
| | - Alan Le Moan
- Department of Marine SciencesTjärnö Marine LaboratoryUniversity of GothenburgStrömstadSweden
| | - Gerrit A. Martens
- Department of Marine SciencesTjärnö Marine LaboratoryUniversity of GothenburgStrömstadSweden
- Present address:
Institute of ZoologyUniversity of HamburgHamburgGermany.
| | - Per R. Jonsson
- Department of Marine SciencesTjärnö Marine LaboratoryUniversity of GothenburgStrömstadSweden
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8
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Dool SE, Picker MD, Eberhard MJB. Limited dispersal and local adaptation promote allopatric speciation in a biodiversity hotspot. Mol Ecol 2021; 31:279-295. [PMID: 34643310 DOI: 10.1111/mec.16219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 09/30/2021] [Accepted: 10/04/2021] [Indexed: 01/20/2023]
Abstract
Recently diverged or diverging populations can offer unobstructed insights into early barriers to gene flow during the initial stages of speciation. The current study utilised a novel insect system (order Mantophasmatodea) to shed light on the early drivers of speciation. The members of this group have limited dispersal abilities, small allopatric distributions and strong habitat associations in the Cape Floristic Region biodiversity hotspot in South Africa. Sister taxa from the diverse family Austrophasmatidae were chosen as focal species (Karoophasma biedouwense, K. botterkloofense). Population genetics and Generalized Dissimilarity Modelling (GDM) were used to characterise spatial patterns of genetic variation and evaluate the contribution of environmental factors to population divergence and speciation. Extensive sampling confirmed the suspected allopatry of these taxa. However, hybrids were identified in a narrow region occurring between the species' distributions. Strong population structure was found over short geographic distances; particularly in K. biedouwense in which geographic distance accounted for 32% of genetic variation over a scale of 50 km (r = .56, p < .001). GDM explained 42%-78% of the deviance in observed genetic dissimilarities. Geographic distance was consistently indicated to be important for between species and within population differentiation, suggesting that limited dispersal ability may be an important neutral driver of divergence. Temperature, altitude, precipitation and vegetation were also indicated as important factors, suggesting the possible role of adaptation to local environmental conditions for species divergence. The discovery of the hybrid-zone, and the multiple allopatric species pairs in Austrophasmatidae support the idea that this could be a promising group to further our understanding of speciation modes.
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Affiliation(s)
- Serena E Dool
- General and Systematic Zoology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.,CBGP, INRAE, CIRAD, IRD, Institut Agro, University of Montpellier, Montpellier, France
| | - Mike D Picker
- Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
| | - Monika J B Eberhard
- General and Systematic Zoology, Zoological Institute and Museum, University of Greifswald, Greifswald, Germany
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9
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Nosil P, Feder JL, Gompert Z. Biodiversity, resilience and the stability of evolutionary systems. Curr Biol 2021; 31:R1149-R1153. [PMID: 34637720 DOI: 10.1016/j.cub.2021.01.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Various macro-evolutionary phenomena, such as long-term stability punctuated by bursts of evolution, are difficult to explain via the micro-evolutionary process of weak selection acting steadily on individual mutations. In contrast, bursts of change are expected if evolutionary systems are complex and balanced, with occasional disruption of balance. Such disruption represents the collapse of resilience, akin to the snapping of an elastic band. It can be driven by external factors, or by self-propagating feedback loops internal to a system. Thus, evolutionary resilience could help explain how evolution generates broader patterns of biodiversity. We outline evidence and tests for this hypothesis, which emphasizes the processes balancing evolution, as urged fifty years ago in ecological genetics and via modern results in a range of systems.
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Affiliation(s)
- Patrik Nosil
- CEFE, Univ. Montpellier, CNRS, EPHE, IRD, Univ Paul Valery Montpellier 3, Montpellier, 34293, France; Department of Biology, Utah State University, Logan, UT 84322, USA.
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
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10
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Hernández-Hernández T, Miller EC, Román-Palacios C, Wiens JJ. Speciation across the Tree of Life. Biol Rev Camb Philos Soc 2021; 96:1205-1242. [PMID: 33768723 DOI: 10.1111/brv.12698] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 01/04/2023]
Abstract
Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.
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Affiliation(s)
- Tania Hernández-Hernández
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A.,Catedrática CONACYT asignada a LANGEBIO-UGA Cinvestav, Libramiento Norte Carretera León Km 9.6, 36821, Irapuato, Guanajuato, Mexico
| | - Elizabeth C Miller
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - Cristian Román-Palacios
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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11
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Thia JA, McGuigan K, Liggins L, Figueira WF, Bird CE, Mather A, Evans JL, Riginos C. Genetic and phenotypic variation exhibit both predictable and stochastic patterns across an intertidal fish metapopulation. Mol Ecol 2021; 30:4392-4414. [PMID: 33544414 DOI: 10.1111/mec.15829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 01/12/2021] [Accepted: 01/28/2021] [Indexed: 11/28/2022]
Abstract
Interactions among selection, gene flow, and drift affect the trajectory of adaptive evolution. In natural populations, the direction and magnitude of these processes can be variable across different spatial, temporal, or ontogenetic scales. Consequently, variability in evolutionary processes affects the predictability or stochasticity of microevolutionary outcomes. We studied an intertidal fish, Bathygobius cocosensis (Bleeker, 1854), to understand how space, time, and life stage structure genetic and phenotypic variation in a species with potentially extensive dispersal and a complex life cycle (larval dispersal preceding benthic recruitment). We sampled juvenile and adult life stages, at three sites, over three years. Genome-wide SNPs uncovered a pattern of chaotic genetic patchiness, that is, weak-but-significant patchy spatial genetic structure that was variable through time and between life stages. Outlier locus analyses suggested that targets of spatially divergent selection were mostly temporally variable, though a significant number of spatial outlier loci were shared between life stages. Head shape, a putatively ecologically responsive (adaptive) phenotype in B. cocosensis also exhibited high temporal variability within sites. However, consistent spatial relationships between sites indicated that environmental similarities among sites may generate predictable phenotype distributions across space. Our study highlights the complex microevolutionary dynamics of marine systems, where consideration of multiple ecological dimensions can reveal both predictable and stochastic patterns in the distributions of genetic and phenotypic variation. Such considerations probably apply to species that possess short, complex life cycles, have large dispersal potential and fecundities, and that inhabit heterogeneous environments.
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Affiliation(s)
- Joshua A Thia
- School of Biological Sciences, The University of Queensland, Saint Lucia, QLD, Australia.,School of BioSciences, The University of Melbourne, Melbourne, VIC., Australia
| | - Katrina McGuigan
- School of Biological Sciences, The University of Queensland, Saint Lucia, QLD, Australia
| | - Libby Liggins
- School of Natural and Computational Sciences, Massey University, Auckland, New Zealand
| | - Will F Figueira
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Christopher E Bird
- Department of Life Sciences, Texas A&M University Corpus Christi, Corpus Christi, TX, USA
| | - Andrew Mather
- School of Biological Sciences, The University of Queensland, Saint Lucia, QLD, Australia
| | - Jennifer L Evans
- School of Biological Sciences, The University of Queensland, Saint Lucia, QLD, Australia
| | - Cynthia Riginos
- School of Biological Sciences, The University of Queensland, Saint Lucia, QLD, Australia
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12
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Muschick M, Soria-Carrasco V, Feder JL, Gompert Z, Nosil P. Adaptive zones shape the magnitude of premating reproductive isolation in Timema stick insects. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190541. [PMID: 32654646 DOI: 10.1098/rstb.2019.0541] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Simpson's fossil-record inspired model of 'adaptive zones' proposes that evolution is dominated by small fluctuations within adaptive zones, occasionally punctuated by larger shifts between zones. This model can help explain why the process of population divergence often results in weak or moderate reproductive isolation (RI), rather than strong RI and distinct species. Applied to the speciation process, the adaptive zones hypothesis makes two inter-related predictions: (i) large shifts between zones are relatively rare, (ii) when large shifts do occur they generate stronger RI than shifts within zones. Here, we use ecological, phylogenetic and behavioural data to test these predictions in Timema stick insects. We show that host use in Timema is dominated by moderate shifts within the systematic divisions of flowering plants and conifers, with only a few extreme shifts between these divisions. However, when extreme shifts occur, they generate greater RI than do more moderate shifts. Our results support the adaptive zones model, and suggest that the net contribution of ecological shifts to diversification is dependent on both their magnitude and frequency. We discuss the generality of our findings in the light of emerging evidence from diverse taxa that the evolution of RI is not always the only factor determining the origin of species diversity. This article is part of the theme issue 'Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
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Affiliation(s)
- Moritz Muschick
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Department of Fish Ecology and Evolution, Eawag, Swiss Federal Institute for Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland.,Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Víctor Soria-Carrasco
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Jeffrey L Feder
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Zach Gompert
- Department of Biology, Utah State University, Logan, UT 84322, USA
| | - Patrik Nosil
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.,Center for Evolution and Functional Ecology, CNRS, 34000 Montpellier, France
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13
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Brady SP, Bolnick DI, Barrett RDH, Chapman L, Crispo E, Derry AM, Eckert CG, Fraser DJ, Fussmann GF, Gonzalez A, Guichard F, Lamy T, Lane J, McAdam AG, Newman AEM, Paccard A, Robertson B, Rolshausen G, Schulte PM, Simons AM, Vellend M, Hendry A. Understanding Maladaptation by Uniting Ecological and Evolutionary Perspectives. Am Nat 2019; 194:495-515. [PMID: 31490718 DOI: 10.1086/705020] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Evolutionary biologists have long trained their sights on adaptation, focusing on the power of natural selection to produce relative fitness advantages while often ignoring changes in absolute fitness. Ecologists generally have taken a different tack, focusing on changes in abundance and ranges that reflect absolute fitness while often ignoring relative fitness. Uniting these perspectives, we articulate various causes of relative and absolute maladaptation and review numerous examples of their occurrence. This review indicates that maladaptation is reasonably common from both perspectives, yet often in contrasting ways. That is, maladaptation can appear strong from a relative fitness perspective, yet populations can be growing in abundance. Conversely, resident individuals can appear locally adapted (relative to nonresident individuals) yet be declining in abundance. Understanding and interpreting these disconnects between relative and absolute maladaptation, as well as the cases of agreement, is increasingly critical in the face of accelerating human-mediated environmental change. We therefore present a framework for studying maladaptation, focusing in particular on the relationship between absolute and relative fitness, thereby drawing together evolutionary and ecological perspectives. The unification of these ecological and evolutionary perspectives has the potential to bring together previously disjunct research areas while addressing key conceptual issues and specific practical problems.
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14
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Hendry AP, Schoen DJ, Wolak ME, Reid JM. The Contemporary Evolution of Fitness. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2018. [DOI: 10.1146/annurev-ecolsys-110617-062358] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The rate of evolution of population mean fitness informs how selection acting in contemporary populations can counteract environmental change and genetic degradation (mutation, gene flow, drift, recombination). This rate influences population increases (e.g., range expansion), population stability (e.g., cryptic eco-evolutionary dynamics), and population recovery (i.e., evolutionary rescue). We review approaches for estimating such rates, especially in wild populations. We then review empirical estimates derived from two approaches: mutation accumulation (MA) and additive genetic variance in fitness (IAw). MA studies inform how selection counters genetic degradation arising from deleterious mutations, typically generating estimates of <1% per generation. IAw studies provide an integrated prediction of proportional change per generation, nearly always generating estimates of <20% and, more typically, <10%. Overall, considerable, but not unlimited, evolutionary potential exists in populations facing detrimental environmental or genetic change. However, further studies with diverse methods and species are required for more robust and general insights.
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Affiliation(s)
- Andrew P. Hendry
- Redpath Museum, McGill University, Montréal, Québec H3A 0C4, Canada
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Daniel J. Schoen
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Matthew E. Wolak
- Department of Biological Sciences, Auburn University, Auburn, Alabama 36849, USA
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
| | - Jane M. Reid
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom
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15
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Niu Y, Chen Z, Stevens M, Sun H. Divergence in cryptic leaf colour provides local camouflage in an alpine plant. Proc Biol Sci 2017; 284:20171654. [PMID: 28978734 PMCID: PMC5647307 DOI: 10.1098/rspb.2017.1654] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 08/31/2017] [Indexed: 11/12/2022] Open
Abstract
The efficacy of camouflage through background matching is highly environment-dependent, often resulting in intraspecific colour divergence in animals to optimize crypsis in different visual environments. This phenomenon is largely unexplored in plants, although several lines of evidence suggest they do use crypsis to avoid damage by herbivores. Using Corydalis hemidicentra, an alpine plant with cryptic leaf colour, we quantified background matching between leaves and surrounding rocks in five populations based on an approximate model of their butterfly enemy's colour perception. We also investigated the pigment basis of leaf colour variation and the association between feeding risk and camouflage efficacy. We show that plants exhibit remarkable colour divergence between populations, consistent with differences in rock appearances. Leaf colour varies because of a different quantitative combination of two basic pigments-chlorophyll and anthocyanin-plus different air spaces. As expected, leaf colours are better matched against their native backgrounds than against foreign ones in the eyes of the butterfly. Furthermore, improved crypsis tends to be associated with a higher level of feeding risk. These results suggest that divergent cryptic leaf colour may have evolved to optimize local camouflage in various visual environments, extending our understanding of colour evolution and intraspecific phenotype diversity in plants.
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Affiliation(s)
- Yang Niu
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
| | - Zhe Chen
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Martin Stevens
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
| | - Hang Sun
- Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, 132 Lanhei Road, Kunming 650201, Yunnan, China
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16
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Jahnke M, Casagrandi R, Melià P, Schiavina M, Schultz ST, Zane L, Procaccini G. Potential and realized connectivity of the seagrassPosidonia oceanicaand their implication for conservation. DIVERS DISTRIB 2017. [DOI: 10.1111/ddi.12633] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare; Roma Italy
| | - Paco Melià
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare; Roma Italy
| | - Marcello Schiavina
- Dipartimento di Elettronica, Informazione e Bioingegneria; Politecnico di Milano; Milano Italy
- Consorzio Nazionale Interuniversitario per le Scienze del Mare; Roma Italy
| | | | - Lorenzo Zane
- Consorzio Nazionale Interuniversitario per le Scienze del Mare; Roma Italy
- Dipartimento di Biologia; Università di Padova; Padova Italy
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17
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18
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Fitzpatrick SW, Handelsman CA, Torres-Dowdall J, Ruell EW, Broder ED, Kronenberger JA, Reznick DN, Ghalambor CK, Angeloni LM, Funk WC. Gene Flow Constrains and Facilitates Genetically Based Divergence in Quantitative Traits. COPEIA 2017. [DOI: 10.1643/ci-16-559] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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19
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Lemos-Costa P, Martins AB, Thompson JN, de Aguiar MAM. Gene flow and metacommunity arrangement affects coevolutionary dynamics at the mutualism-antagonism interface. J R Soc Interface 2017; 14:rsif.2016.0989. [PMID: 28566509 DOI: 10.1098/rsif.2016.0989] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 05/08/2017] [Indexed: 11/12/2022] Open
Abstract
Interspecific interactions are affected by community context and, as a consequence, show spatial variation in magnitude and sign. The selective forces imposed by interactions at the mutualism-antagonism interface are a consequence of the traits involved and their matching between species. If mutualistic and antagonistic communities are linked by gene flow, coevolution between a pair of interacting species is influenced by how selection varies in space. Here we investigate the effects of metacommunity arrangement, i.e. patterns of connection between communities and the number of communities, on the coevolutionary dynamics between two species for which the sign and magnitude of the interaction varies across the landscape. We quantify coevolutionary outcome as an index that can be decomposed into the contribution of intraspecific genetic diversity and interspecific interaction. We show that polymorphisms and mismatches are an expected outcome, which is influenced by spatial structure, interaction strength and the degree of gene flow. The index describes how variation is distributed within and between species, and provides information on the directionality of the mismatches and polymorphisms. Finally, we argue that depending on metacommunity arrangement, some communities have disproportionate roles in maintaining genetic diversity, with implications for the coevolution of interacting species in a fragmented landscape.
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Affiliation(s)
- Paula Lemos-Costa
- Programa de pós-graduação em Ecologia-Instituto de Biologia, Universidade Estadual de Campinas, Unicamp, 13083-865, Campinas/SP, Brazil
| | - Ayana B Martins
- Instituto de Física 'Gleb Wataghin', Universidade Estadual de Campinas, Unicamp, 13083-859, Campinas/SP, Brazil.,Department of Fish Ecology and Evolution, Center of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
| | - John N Thompson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| | - Marcus A M de Aguiar
- Instituto de Física 'Gleb Wataghin', Universidade Estadual de Campinas, Unicamp, 13083-859, Campinas/SP, Brazil
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20
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Farkas TE, Mononen T, Comeault AA, Nosil P. Observational evidence that maladaptive gene flow reduces patch occupancy in a wild insect metapopulation. Evolution 2016; 70:2879-2888. [PMID: 27683197 DOI: 10.1111/evo.13076] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 08/25/2016] [Accepted: 09/11/2016] [Indexed: 01/27/2023]
Abstract
Theory predicts that dispersal throughout metapopulations has a variety of consequences for the abundance and distribution of species. Immigration is predicted to increase abundance and habitat patch occupancy, but gene flow can have both positive and negative demographic consequences. Here, we address the eco-evolutionary effects of dispersal in a wild metapopulation of the stick insect Timema cristinae, which exhibits variable degrees of local adaptation throughout a heterogeneous habitat patch network of two host-plant species. To disentangle the ecological and evolutionary contributions of dispersal to habitat patch occupancy and abundance, we contrasted the effects of connectivity to populations inhabiting conspecific host plants and those inhabiting the alternate host plant. Both types of connectivity should increase patch occupancy and abundance through increased immigration and sharing of beneficial alleles through gene flow. However, connectivity to populations inhabiting the alternate host-plant species may uniquely cause maladaptive gene flow that counters the positive demographic effects of immigration. Supporting these predictions, we find the relationship between patch occupancy and alternate-host connectivity to be significantly smaller in slope than the relationship between patch occupancy and conspecific-host connectivity. Our findings illustrate the ecological and evolutionary roles of dispersal in driving the distribution and abundance of species.
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Affiliation(s)
- Timothy E Farkas
- Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.,Ecology and Evolutionary Biology, University of Connecticut, Storrs, Connecticut, 06269
| | - Tommi Mononen
- Metapopulation Research Centre, Biosciences, University of Helsinki, Helsinki, 00014, Finland.,Neuroscience and Biomedical Engineering, Aalto University, Aalto, FI-00076, Finland
| | - Aaron A Comeault
- Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom.,Department of Biology, University of North Carolina, Durham, North Carolina, 27599
| | - Patrik Nosil
- Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, United Kingdom
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21
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Stotz GC, Gianoli E, Cahill JF. Spatial pattern of invasion and the evolutionary responses of native plant species. Evol Appl 2016; 9:939-51. [PMID: 27606003 PMCID: PMC4999525 DOI: 10.1111/eva.12398] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 05/22/2016] [Indexed: 01/02/2023] Open
Abstract
Invasive plant species can have a strong negative impact on the resident native species, likely imposing new selective pressures on them. Altered selective pressures may result in evolutionary changes in some native species, reducing competitive exclusion and allowing for coexistence with the invader. Native genotypes that are able to coexist with strong invaders may represent a valuable resource for management efforts. A better understanding of the conditions under which native species are more, or less, likely to adapt to an invader is necessary to incorporate these eco-evolutionary dynamics into management strategies. We propose that the spatial structure of invasion, in particular the size and isolation of invaded patches, is one factor which can influence the evolutionary responses of native species through modifying gene flow and the strength of selection. We present a conceptual model in which large, dense, and well-connected patches result in a greater likelihood of native species adaptation. We also identify characteristics of the interacting species that may influence the evolutionary response of native species to invasion and outline potential management implications. Identifying areas of rapid evolutionary change may offer one additional tool to managers in their effort to conserve biodiversity in the face of invasion.
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Affiliation(s)
- Gisela C Stotz
- Department of Biological Sciences University of Alberta Edmonton AB Canada
| | - Ernesto Gianoli
- Departamento de Biología Universidad de la Serena La Serena Chile; Departmento de Botánica Universidad de Concepción Concepción Chile
| | - James F Cahill
- Department of Biological Sciences University of Alberta Edmonton AB Canada
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22
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Richardson JL, Brady SP, Wang IJ, Spear SF. Navigating the pitfalls and promise of landscape genetics. Mol Ecol 2016; 25:849-63. [PMID: 26756865 DOI: 10.1111/mec.13527] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/12/2015] [Accepted: 01/07/2016] [Indexed: 12/17/2022]
Abstract
The field of landscape genetics has been evolving rapidly since its emergence in the early 2000s. New applications, techniques and criticisms of techniques appear like clockwork with each new journal issue. The developments are an encouraging, and at times bewildering, sign of progress in an exciting new field of study. However, we suggest that the rapid expansion of landscape genetics has belied important flaws in the development of the field, and we add an air of caution to this breakneck pace of expansion. Specifically, landscape genetic studies often lose sight of the fundamental principles and complex consequences of gene flow, instead favouring simplistic interpretations and broad inferences not necessarily warranted by the data. Here, we describe common pitfalls that characterize such studies, and provide practical guidance to improve landscape genetic investigation, with careful consideration of inferential limits, scale, replication, and the ecological and evolutionary context of spatial genetic patterns. Ultimately, the utility of landscape genetics will depend on translating the relationship between gene flow and landscape features into an understanding of long-term population outcomes. We hope the perspective presented here will steer landscape genetics down a more scientifically sound and productive path, garnering a field that is as informative in the future as it is popular now.
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Affiliation(s)
- Jonathan L Richardson
- Department of Biology, Providence College, 1 Cunningham Square, Providence, RI, 02918, USA
| | - Steven P Brady
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Ian J Wang
- Department of Environmental Science, Policy & Management, University of California, Berkeley, CA, 94720, USA
| | - Stephen F Spear
- The Orianne Society, 100 Phoenix Rd., Athens, GA, 30605, USA
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23
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Body size, not maladaptive gene flow, explains death-feigning behaviour in Timema cristinae stick insects. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9832-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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24
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Brahimi A, Tarai N, Benhassane A, Henrard A, Libois R. Genetic and morphological consequences of Quaternary glaciations: A relic barbel lineage (Luciobarbus pallaryi, Cyprinidae) of Guir Basin (Algeria). C R Biol 2016; 339:83-98. [PMID: 26874458 DOI: 10.1016/j.crvi.2015.12.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 12/23/2015] [Accepted: 12/25/2015] [Indexed: 11/18/2022]
Abstract
Climatic variations during the Quaternary period had a considerable impact on landscapes and habitat fragmentation (rivers) in North Africa. These historical events can have significant consequences on the genetic structure of the populations. Indeed, geographically separated and genetically isolated populations tend to differentiate themselves through time, eventually becoming distinct lineages, allowing new species to emerge in later generations. The aim of the present study is to use genetic and morphological techniques to evaluate the major role of the Saalian glaciation (Middle Quaternary) in the establishment of the geographic space and in the evolution of the intraspecific genetic diversity, by tracing the demographic history of barbels belonging to the Luciobarbus pallaryi (Cyprinidae) species in the Guir Basin (Algeria). In this context, two populations, from two distinct and isolated sites, were studied. Analysis of the cytochrome b (cyt b) mitochondrial markers and of the "D-loop" control region has shown that the "upstream" and "downstream" Guir populations are genetically differentiated. The molecular analyses suggest that the upstream population was disconnected from this hydrographic system during the Saalian glaciation period of the Quaternary. Subsequently, it was isolated in the foggaras underground waters in the Great Western Erg, at approximately 320 000 years BP, creating, through a bottleneck effect, a new allopatric lineage referred to as "Adrar". Conversely, the high genetic diversity in the upstream Guir (Bechar) population suggests that the stock is globally in expansion. These barbels (n=52) were also examined with meristic, morphometric, osteological, and biological features. These data also reveal a complete discrimination between the two populations, with a remarkable and distinctive behavioural adaptation for the Adrar specimens: neoteny.
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Affiliation(s)
- Amina Brahimi
- Department of Agronomy, University of Mohamed Kheider, 07000 Biskra, Algeria; Zoogeography Research Unit, Department of Biology, Ecology and Evolution, University of Liège, chemin de la vallée 4 (bâtiment B22), 4000 Sart Tilman, Belgium.
| | - Nacer Tarai
- Department of Agronomy, University of Mohamed Kheider, 07000 Biskra, Algeria
| | | | - Arnaud Henrard
- Earth and life Institute, Biodiversity research Center, UCL-17. 07. 04, bâtiment Carnoy, Croix-du-Sud, 5, 1348 Louvain-la-Neuve, Belgium; Royal Museum for Central Africa, 3080 Tervuren, Belgium
| | - Roland Libois
- Zoogeography Research Unit, Department of Biology, Ecology and Evolution, University of Liège, chemin de la vallée 4 (bâtiment B22), 4000 Sart Tilman, Belgium
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25
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Camacho C, Sáez P, Sánchez S, Palacios S, Molina C, Potti J. The road to opportunities: landscape change promotes body-size divergence in a highly mobile species. Curr Zool 2016; 62:7-14. [PMID: 29491885 PMCID: PMC5804134 DOI: 10.1093/cz/zov008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/23/2015] [Indexed: 11/16/2022] Open
Abstract
Landscape change provides a suitable framework for investigating population-level responses to novel ecological pressures. However, relatively little attention has been paid to examine the potential influence of landscape change on the geographic scale of population differentiation. Here, we tested for morphological differentiation of red-necked nightjars Caprimulgus ruficollis breeding in a managed property and a natural reserve situated less than 10 km apart. At both sites, we also estimated site fidelity over 5 years and quantified the potential foraging opportunities for nightjars. Breeding birds in the managed habitat were significantly larger in size—as indexed by keel length—than those in the natural one. However, there were no significant differences in wing or tail length. Immigration from neighboring areas was almost negligible and, furthermore, no individual (out of 1130 captures overall) exchanged habitats between years, indicating strong site fidelity. Food supply for nightjars was equally abundant in both habitats, but the availability of foraging sites was remarkably higher in the managed property. As a result, nightjars—particularly fledglings—in the latter habitat benefited from increased foraging opportunities in relation to those in the natural site. It seems likely that the fine-scale variation in nightjar morphology reflects a phenotypic response to unequal local conditions, since non-random dispersal or differential mortality had been determined not to be influential. High site fidelity appears to contribute to the maintenance of body-size differences between the two habitats. Results from this nightjar population highlight the potential of human-induced landscape change to promote population-level responses at exceedingly small geographic scales.
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Affiliation(s)
- Carlos Camacho
- Department of Evolutionary Ecology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio, 41092 Seville, Spain
| | - Pedro Sáez
- Department of Environmental Biology and Public Health. University of Huelva. Av. Andalucía, 21071 Huelva, Spain
| | - Sonia Sánchez
- Department of Evolutionary Ecology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio, 41092 Seville, Spain
| | - Sebastián Palacios
- Department of Conservation Biology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio, 41092 Seville, Spain, and
| | - Carlos Molina
- Sociedad Española de Ornitología. Centro Ornitológico Francisco Bernis. Paseo Marismeño sn, 21750 Huelva, Spain
| | - Jaime Potti
- Department of Evolutionary Ecology, Estación Biológica de Doñana-CSIC, Av. Américo Vespucio, 41092 Seville, Spain
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26
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Lozier JD, Jackson JM, Dillon ME, Strange JP. Population genomics of divergence among extreme and intermediate color forms in a polymorphic insect. Ecol Evol 2016; 6:1075-91. [PMID: 26811748 PMCID: PMC4722823 DOI: 10.1002/ece3.1928] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 12/08/2015] [Accepted: 12/09/2015] [Indexed: 01/01/2023] Open
Abstract
Geographic variation in insect coloration is among the most intriguing examples of rapid phenotypic evolution and provides opportunities to study mechanisms of phenotypic change and diversification in closely related lineages. The bumble bee Bombus bifarius comprises two geographically disparate color groups characterized by red‐banded and black‐banded abdominal pigmentation, but with a range of spatially and phenotypically intermediate populations across western North America. Microsatellite analyses have revealed that B. bifarius in the USA are structured into two major groups concordant with geography and color pattern, but also suggest ongoing gene flow among regional populations. In this study, we better resolve the relationships among major color groups to better understand evolutionary mechanisms promoting and maintaining such polymorphism. We analyze >90,000 and >25,000 single‐nucleotide polymorphisms derived from transcriptome (RNAseq) and double digest restriction site associated DNA sequencing (ddRAD), respectively, in representative samples from spatial and color pattern extremes in B. bifarius as well as phenotypic and geographic intermediates. Both ddRAD and RNAseq data illustrate substantial genome‐wide differentiation of the red‐banded (eastern) color form from both black‐banded (western) and intermediate (central) phenotypes and negligible differentiation among the latter populations, with no obvious admixture among bees from the two major lineages. Results thus indicate much stronger background differentiation among B. bifarius lineages than expected, highlighting potential challenges for revealing loci underlying color polymorphism from population genetic data alone. These findings will have significance for resolving taxonomic confusion in this species and in future efforts to investigate color‐pattern evolution in B. bifarius and other polymorphic bumble bee species.
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Affiliation(s)
- Jeffrey D Lozier
- Department of Biological Sciences University of Alabama Tuscaloosa Alabama
| | - Jason M Jackson
- Department of Biological Sciences University of Alabama Tuscaloosa Alabama
| | - Michael E Dillon
- Department of Zoology & Physiology and Program in Ecology University of Wyoming Laramie Wyoming
| | - James P Strange
- USDA-ARS Pollinating Insect Research Unit Utah State University Logan Utah
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27
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Paz-Vinas I, Loot G, Stevens VM, Blanchet S. Evolutionary processes driving spatial patterns of intraspecific genetic diversity in river ecosystems. Mol Ecol 2015; 24:4586-604. [PMID: 26284462 DOI: 10.1111/mec.13345] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 07/30/2015] [Accepted: 08/13/2015] [Indexed: 01/17/2023]
Abstract
Describing, understanding and predicting the spatial distribution of genetic diversity is a central issue in biological sciences. In river landscapes, it is generally predicted that neutral genetic diversity should increase downstream, but there have been few attempts to test and validate this assumption across taxonomic groups. Moreover, it is still unclear what are the evolutionary processes that may generate this apparent spatial pattern of diversity. Here, we quantitatively synthesized published results from diverse taxa living in river ecosystems, and we performed a meta-analysis to show that a downstream increase in intraspecific genetic diversity (DIGD) actually constitutes a general spatial pattern of biodiversity that is repeatable across taxa. We further demonstrated that DIGD was stronger for strictly waterborne dispersing than for overland dispersing species. However, for a restricted data set focusing on fishes, there was no evidence that DIGD was related to particular species traits. We then searched for general processes underlying DIGD by simulating genetic data in dendritic-like river systems. Simulations revealed that the three processes we considered (downstream-biased dispersal, increase in habitat availability downstream and upstream-directed colonization) might generate DIGD. Using random forest models, we identified from simulations a set of highly informative summary statistics allowing discriminating among the processes causing DIGD. Finally, combining these discriminant statistics and approximate Bayesian computations on a set of twelve empirical case studies, we hypothesized that DIGD were most likely due to the interaction of two of these three processes and that contrary to expectation, they were not solely caused by downstream-biased dispersal.
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Affiliation(s)
- I Paz-Vinas
- Centre National de la Recherche Scientifique (CNRS), École Nationale de Formation Agronomique (ENFA), UMR 5174 EDB (Laboratoire Évolution & Diversité Biologique), Université Paul Sabatier, 118 route de Narbonne, 31062, Toulouse Cedex 4, France.,UPS, UMR 5174 (EDB), Université de Toulouse, 118 route de Narbonne, 31062, Toulouse Cedex 4, France.,UMR 7263 - IMBE, Équipe EGE, Centre Saint-Charles, Aix-Marseille Université, CNRS, IRD, Université d'Avignon et des Pays de Vaucluse, Case 36, 3 place Victor Hugo, 13331, Marseille Cedex 3, France
| | - G Loot
- UPS, UMR 5174 (EDB), Université de Toulouse, 118 route de Narbonne, 31062, Toulouse Cedex 4, France.,Station d'Écologie Expérimentale du CNRS à Moulis, USR 2936, Centre National de la Recherche Scientifique (CNRS), 2 route du CNRS, 09200, Moulis, France
| | - V M Stevens
- Station d'Écologie Expérimentale du CNRS à Moulis, USR 2936, Centre National de la Recherche Scientifique (CNRS), 2 route du CNRS, 09200, Moulis, France
| | - S Blanchet
- Centre National de la Recherche Scientifique (CNRS), École Nationale de Formation Agronomique (ENFA), UMR 5174 EDB (Laboratoire Évolution & Diversité Biologique), Université Paul Sabatier, 118 route de Narbonne, 31062, Toulouse Cedex 4, France.,Station d'Écologie Expérimentale du CNRS à Moulis, USR 2936, Centre National de la Recherche Scientifique (CNRS), 2 route du CNRS, 09200, Moulis, France
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28
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Konijnendijk N, Shikano T, Daneels D, Volckaert FAM, Raeymaekers JAM. Signatures of selection in the three-spined stickleback along a small-scale brackish water - freshwater transition zone. Ecol Evol 2015; 5:4174-86. [PMID: 26445666 PMCID: PMC4588664 DOI: 10.1002/ece3.1671] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/13/2015] [Accepted: 07/22/2015] [Indexed: 01/31/2023] Open
Abstract
Local adaptation is often obvious when gene flow is impeded, such as observed at large spatial scales and across strong ecological contrasts. However, it becomes less certain at small scales such as between adjacent populations or across weak ecological contrasts, when gene flow is strong. While studies on genomic adaptation tend to focus on the former, less is known about the genomic targets of natural selection in the latter situation. In this study, we investigate genomic adaptation in populations of the three-spined stickleback Gasterosteus aculeatus L. across a small-scale ecological transition with salinities ranging from brackish to fresh. Adaptation to salinity has been repeatedly demonstrated in this species. A genome scan based on 87 microsatellite markers revealed only few signatures of selection, likely owing to the constraints that homogenizing gene flow puts on adaptive divergence. However, the detected loci appear repeatedly as targets of selection in similar studies of genomic adaptation in the three-spined stickleback. We conclude that the signature of genomic selection in the face of strong gene flow is weak, yet detectable. We argue that the range of studies of genomic divergence should be extended to include more systems characterized by limited geographical and ecological isolation, which is often a realistic setting in nature.
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Affiliation(s)
- Nellie Konijnendijk
- Laboratory of Biodiversity and Evolutionary Genomics University of Leuven Ch. Deberiotstraat 32, B-3000 Leuven Belgium
| | - Takahito Shikano
- Ecological Genetics Research Unit Department of Biosciences University of Helsinki P.O. Box 65 FI-000 14 Helsinki Finland
| | - Dorien Daneels
- Laboratory of Biodiversity and Evolutionary Genomics University of Leuven Ch. Deberiotstraat 32, B-3000 Leuven Belgium
| | - Filip A M Volckaert
- Laboratory of Biodiversity and Evolutionary Genomics University of Leuven Ch. Deberiotstraat 32, B-3000 Leuven Belgium
| | - Joost A M Raeymaekers
- Laboratory of Biodiversity and Evolutionary Genomics University of Leuven Ch. Deberiotstraat 32, B-3000 Leuven Belgium
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29
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How maladaptation can structure biodiversity: eco-evolutionary island biogeography. Trends Ecol Evol 2015; 30:154-60. [PMID: 25666433 DOI: 10.1016/j.tree.2015.01.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 11/20/2022]
Abstract
Current research on eco-evolutionary dynamics is mainly concerned with understanding the role of rapid (or 'contemporary') evolution in structuring ecological patterns. We argue that the current eco-evolutionary research program, which focuses largely on natural selection, should be expanded to more explicitly consider other evolutionary processes such as gene flow. Because multiple evolutionary processes interact to generate quantitative variation in the degree of local maladaptation, we focus on how studying the ecological effects of maladaptation will lead to a more comprehensive view of how evolution can influence ecology. We explore how maladaptation can influence ecology through the lens of island biogeography theory, which yields some novel predictions, such as patch isolation increasing species richness.
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30
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Fitzpatrick SW, Gerberich JC, Kronenberger JA, Angeloni LM, Funk WC. Locally adapted traits maintained in the face of high gene flow. Ecol Lett 2014; 18:37-47. [PMID: 25363522 DOI: 10.1111/ele.12388] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 06/06/2014] [Accepted: 10/01/2014] [Indexed: 11/26/2022]
Abstract
Gene flow between phenotypically divergent populations can disrupt local adaptation or, alternatively, may stimulate adaptive evolution by increasing genetic variation. We capitalised on historical Trinidadian guppy transplant experiments to test the phenotypic effects of increased gene flow caused by replicated introductions of adaptively divergent guppies, which were translocated from high- to low-predation environments. We sampled two native populations prior to the onset of gene flow, six historic introduction sites, introduction sources and multiple downstream points in each basin. Extensive gene flow from introductions occurred in all streams, yet adaptive phenotypic divergence across a gradient in predation level was maintained. Descendants of guppies from a high-predation source site showed high phenotypic similarity with native low-predation guppies in as few as ~12 generations after gene flow, likely through a combination of adaptive evolution and phenotypic plasticity. Our results demonstrate that locally adapted phenotypes can be maintained despite extensive gene flow from divergent populations.
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Affiliation(s)
- S W Fitzpatrick
- Department of Biology, Colorado State University, 1878 Campus Delivery, Fort Collins, CO, 80523, USA
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31
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Tomozawa M, Nunome M, Suzuki H, Ono H. Effect of founding events on coat colour polymorphism of Apodemus speciosus(Rodentia: Muridae) on the Izu Islands. Biol J Linn Soc Lond 2014. [DOI: 10.1111/bij.12348] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
| | - Mitsuo Nunome
- Laboratory of Animal Genetics; Department of Applied Molecular Biosciences; Graduate School of Bioagricultural Sciences; Nagoya University; Furo-cho Chikusa-ku Nagoya 464-8601 Japan
| | - Hitoshi Suzuki
- Laboratory of Ecology and Genetics; Graduate School of Environmental Science; Hokkaido University; North 10 West 5 Kita-ku Sapporo 060-0810 Japan
| | - Hirotake Ono
- Department of Biology; Keio University; Yokohama 223-8521 Japan
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32
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Ley A, Hardy O. Contrasting patterns of gene flow between sister plant species in the understorey of African moist forests – The case of sympatric and parapatric Marantaceae species. Mol Phylogenet Evol 2014; 77:264-74. [DOI: 10.1016/j.ympev.2014.04.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 02/20/2014] [Accepted: 04/17/2014] [Indexed: 11/29/2022]
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33
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Comeault AA, Soria-Carrasco V, Gompert Z, Farkas TE, Buerkle CA, Parchman TL, Nosil P. Genome-Wide Association Mapping of Phenotypic Traits Subject to a Range of Intensities of Natural Selection in Timema cristinae. Am Nat 2014; 183:711-27. [DOI: 10.1086/675497] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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34
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Bourne EC, Bocedi G, Travis JMJ, Pakeman RJ, Brooker RW, Schiffers K. Between migration load and evolutionary rescue: dispersal, adaptation and the response of spatially structured populations to environmental change. Proc Biol Sci 2014; 281:20132795. [PMID: 24452022 PMCID: PMC3906938 DOI: 10.1098/rspb.2013.2795] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 12/13/2013] [Indexed: 11/12/2022] Open
Abstract
The evolutionary potential of populations is mainly determined by population size and available genetic variance. However, the adaptability of spatially structured populations may also be affected by dispersal: positively by spreading beneficial mutations across sub-populations, but negatively by moving locally adapted alleles between demes. We develop an individual-based, two-patch, allelic model to investigate the balance between these opposing effects on a population's evolutionary response to rapid climate change. Individual fitness is controlled by two polygenic traits coding for local adaptation either to the environment or to climate. Under conditions of selection that favour the evolution of a generalist phenotype (i.e. weak divergent selection between patches) dispersal has an overall positive effect on the persistence of the population. However, when selection favours locally adapted specialists, the beneficial effects of dispersal outweigh the associated increase in maladaptation for a narrow range of parameter space only (intermediate selection strength and low linkage among loci), where the spread of beneficial climate alleles is not strongly hampered by selection against non-specialists. Given that local selection across heterogeneous and fragmented landscapes is common, the complex effect of dispersal that we describe will play an important role in determining the evolutionary dynamics of many species under rapidly changing climate.
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Affiliation(s)
- Elizabeth C. Bourne
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
- Institute of Biological and Environmental Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
- Institute für Biologie—Botanik, Freie Universität Berlin, Altensteinstrasse 6, Berlin 14195, Germany
| | - Greta Bocedi
- Institute of Biological and Environmental Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
| | - Justin M. J. Travis
- Institute of Biological and Environmental Sciences, University of Aberdeen, Zoology Building, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
| | - Robin J. Pakeman
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | - Rob W. Brooker
- The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, UK
| | - Katja Schiffers
- Evolution, Modeling and Analyses of Biodiversity group, Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble Cedex 9, France
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35
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Ingley SJ, Billman EJ, Belk MC, Johnson JB. Morphological divergence driven by predation environment within and between species of Brachyrhaphis fishes. PLoS One 2014; 9:e90274. [PMID: 24587309 PMCID: PMC3936007 DOI: 10.1371/journal.pone.0090274] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 02/01/2014] [Indexed: 11/19/2022] Open
Abstract
Natural selection often results in profound differences in body shape among populations from divergent selective environments. Predation is a well-studied driver of divergence, with predators having a strong effect on the evolution of prey body shape, especially for traits related to escape behavior. Comparative studies, both at the population level and between species, show that the presence or absence of predators can alter prey morphology. Although this pattern is well documented in various species or population pairs, few studies have tested for similar patterns of body shape evolution at multiple stages of divergence within a taxonomic group. Here, we examine morphological divergence associated with predation environment in the livebearing fish genus Brachyrhaphis. We compare differences in body shape between populations of B. rhabdophora from different predation environments to differences in body shape between B. roseni and B. terrabensis (sister species) from predator and predator free habitats, respectively. We found that in each lineage, shape differed between predation environments, consistent with the hypothesis that locomotor function is optimized for either steady swimming (predator free) or escape behavior (predator). Although differences in body shape were greatest between B. roseni and B. terrabensis, we found that much of the total morphological diversification between these species had already been achieved within B. rhabdophora (29% in females and 47% in males). Interestingly, at both levels of divergence we found that early in ontogenetic development, females differed in shape between predation environments; however, as females matured, their body shapes converged on a similar phenotype, likely due to the constraints of pregnancy. Finally, we found that body shape varies with body size in a similar way, regardless of predation environment, in each lineage. Our findings are important because they provide evidence that the same source of selection can drive similar phenotypic divergence independently at multiple divergence levels.
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Affiliation(s)
- Spencer J. Ingley
- Department of Biology, Brigham Young University, Provo, Utah, United States of America
| | - Eric J. Billman
- Department of Biology, Brigham Young University, Provo, Utah, United States of America
| | - Mark C. Belk
- Department of Biology, Brigham Young University, Provo, Utah, United States of America
| | - Jerald B. Johnson
- Department of Biology, Brigham Young University, Provo, Utah, United States of America
- Monte L. Bean Life Science Museum, Brigham Young University, Provo, Utah, United States of America
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Farkas TE, Mononen T, Comeault AA, Hanski I, Nosil P. Evolution of camouflage drives rapid ecological change in an insect community. Curr Biol 2013; 23:1835-43. [PMID: 24055155 DOI: 10.1016/j.cub.2013.07.067] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 06/18/2013] [Accepted: 07/19/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Evolutionary change in individual species has been hypothesized to have far-reaching consequences for entire ecological communities, and such coupling of ecological and evolutionary dynamics ("eco-evolutionary dynamics") has been demonstrated for a variety systems. However, the general importance of evolutionary dynamics for ecological dynamics remains unclear. Here, we investigate how spatial patterns of local adaptation in the stick insect Timema cristinae, driven by the interaction between multiple evolutionary processes, structure metapopulations, communities, and multitrophic interactions. RESULTS Observations of a wild T. cristinae metapopulation show that locally imperfect camouflage reduces population size and that the effect of such maladaptation is comparable to the effects of more traditional ecological factors, including habitat patch size and host-plant species identity. Field manipulations of local adaptation and bird predation support the hypothesis that maladaptation reduces population size through an increase in bird predation. Furthermore, these field experiments show that maladaptation in T. cristinae and consequent increase in bird predation reduce the pooled abundance and species richness of the co-occurring arthropod community, and ultimately cascade to decrease herbivory on host plants. An eco-evolutionary model of the observational data demonstrates that the demographic cost of maladaptation decreases habitat patch occupancy by T. cristinae but enhances metapopulation-level adaptation. CONCLUSIONS The results demonstrate a pervasive effect of ongoing evolution in a spatial context on population and community dynamics. The eco-evolutionary model makes testable predictions about the influence of the spatial configuration of the patch network on metapopulation size and the spatial scale of adaptation.
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Affiliation(s)
- Timothy E Farkas
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK; Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO 80309, USA.
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37
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Mikheyev AS, McBride CS, Mueller UG, Parmesan C, Smee MR, Stefanescu C, Wee B, Singer MC. Host-associated genomic differentiation in congeneric butterflies: now you see it, now you do not. Mol Ecol 2013; 22:4753-66. [DOI: 10.1111/mec.12423] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 06/13/2013] [Accepted: 06/13/2013] [Indexed: 01/20/2023]
Affiliation(s)
| | - Carolyn S. McBride
- Laboratory of Neurogenetics and Behavior; The Rockefeller University; New York NY USA
| | | | - Camille Parmesan
- Integrative Biology; University of Texas; Austin TX 78712 USA
- Marine Institute; Level 3 Marine Bldg.; Plymouth University; Drakes Circus; Plymouth Devon PL4 8AA UK
| | | | - Constanti Stefanescu
- Catalan Butterfly Monitoring Scheme; Museu de Ciències Naturals; Granollers 08402 Spain
- Global Ecology Unit; CREAF; Cerdanyola del Vallès 08193 Spain
| | - Brian Wee
- NEON, Inc. c/o Smithsonian Institution; 1100 Jefferson Drive SW, Suite 3123, MRC 705 Washington DC 20560-0001 USA
| | - Michael C. Singer
- Integrative Biology; University of Texas; Austin TX 78712 USA
- School of Biomedical and Biological Sciences; Plymouth University; Drake Circus; Plymouth PL4 8AA UK
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38
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Roy D, Seehausen O, Nosil P. Sexual dimorphism dominates divergent host plant use in stick insect trophic morphology. BMC Evol Biol 2013; 13:135. [PMID: 23819550 PMCID: PMC3707739 DOI: 10.1186/1471-2148-13-135] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/18/2013] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Clear examples of ecological speciation exist, often involving divergence in trophic morphology. However, substantial variation also exists in how far the ecological speciation process proceeds, potentially linked to the number of ecological axes, traits, or genes subject to divergent selection. In addition, recent studies highlight how differentiation might occur between the sexes, rather than between populations. We examine variation in trophic morphology in two host-plant ecotypes of walking-stick insects (Timema cristinae), known to have diverged in morphological traits related to crypsis and predator avoidance, and to have reached an intermediate point in the ecological speciation process. Here we test how host plant use, sex, and rearing environment affect variation in trophic morphology in this species using traditional multivariate, novel kernel density based and Bayesian morphometric analyses. RESULTS Contrary to expectations, we find limited host-associated divergence in mandible shape. Instead, the main predictor of shape variation is sex, with secondary roles of population of origin and rearing environment. CONCLUSION Our results show that trophic morphology does not strongly contribute to host-adapted ecotype divergence in T. cristinae and that traits can respond to complex selection regimes by diverging along different intraspecific lines, thereby impeding progress toward speciation.
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Affiliation(s)
- Denis Roy
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, ON N9B 3P4, Canada.
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39
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Porter SS. Adaptive divergence in seed color camouflage in contrasting soil environments. THE NEW PHYTOLOGIST 2013; 197:1311-1320. [PMID: 23312014 DOI: 10.1111/nph.12110] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 11/20/2012] [Indexed: 06/01/2023]
Abstract
Although adaptive plant population divergence across contrasting soil conditions is often driven by abiotic soil factors, natural enemies may also contribute. Cryptic matching to the native soil color is a form of defensive camouflage that seeds can use to avoid detection by seed predators. The legume Acmispon wrangelianus occurs across a variety of gray-green serpentine soils and brown nonserpentine soils. Quantitative digital image analysis of seed and soil colors was used to test whether genetically based seed color is a closer match to the color of the native soil than to the color of other nearby soils. Lineages bear seeds that more closely match the color of their native serpentine or nonserpentine soil type than the opposing soil type. Further, even within a soil type, lineages bear seeds with a closer color match to the soil at their native site than to other sites. The striking concordance between seed and native soil color suggests that natural selection for locally camouflaged seed color morphs, probably driven by seed predators, may maintain adaptive divergence in pigmentation, despite the opportunity for migration between soil environments.
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Affiliation(s)
- Stephanie S Porter
- The Department of Integrative Biology, University of California, Berkeley, CA, 94720, USA
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40
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Gompert Z, Lucas LK, Nice CC, Fordyce JA, Alex Buerkle C, Forister ML. Geographically multifarious phenotypic divergence during speciation. Ecol Evol 2013; 3:595-613. [PMID: 23532669 PMCID: PMC3605849 DOI: 10.1002/ece3.445] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/31/2012] [Accepted: 11/12/2012] [Indexed: 11/10/2022] Open
Abstract
Speciation is an important evolutionary process that occurs when barriers to gene flow evolve between previously panmictic populations. Although individual barriers to gene flow have been studied extensively, we know relatively little regarding the number of barriers that isolate species or whether these barriers are polymorphic within species. Herein, we use a series of field and lab experiments to quantify phenotypic divergence and identify possible barriers to gene flow between the butterfly species Lycaeides idas and Lycaeides melissa. We found evidence that L. idas and L. melissa have diverged along multiple phenotypic axes. Specifically, we identified major phenotypic differences in female oviposition preference and diapause initiation, and more moderate divergence in mate preference. Multiple phenotypic differences might operate as barriers to gene flow, as shown by correlations between genetic distance and phenotypic divergence and patterns of phenotypic variation in admixed Lycaeides populations. Although some of these traits differed primarily between species (e.g., diapause initiation), several traits also varied among conspecific populations (e.g., male mate preference and oviposition preference).
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Affiliation(s)
- Zachariah Gompert
- Department of Botany, University of Wyoming Laramie, Wyoming, 82071 ; Department of Biology, Texas State University San Marcos, Texas, 78666
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41
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Nosil P, Parchman TL, Feder JL, Gompert Z. Do highly divergent loci reside in genomic regions affecting reproductive isolation? A test using next-generation sequence data in Timema stick insects. BMC Evol Biol 2012; 12:164. [PMID: 22938057 PMCID: PMC3502483 DOI: 10.1186/1471-2148-12-164] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 08/22/2012] [Indexed: 11/15/2022] Open
Abstract
Background Genetic divergence during speciation with gene flow is heterogeneous across the genome, with some regions exhibiting stronger differentiation than others. Exceptionally differentiated regions are often assumed to experience reduced introgression, i.e., reduced flow of alleles from one population into another because such regions are affected by divergent selection or cause reproductive isolation. In contrast, the remainder of the genome can be homogenized by high introgression. Although many studies have documented variation across the genome in genetic differentiation, there are few tests of this hypothesis that explicitly quantify introgression. Here, we provide such a test using 38,304 SNPs in populations of Timema cristinae stick insects. We quantify whether loci that are highly divergent between geographically separated (‘allopatric’) populations exhibit unusual patterns of introgression in admixed populations. To the extent this is true, highly divergent loci between allopatric populations contribute to reproductive isolation in admixed populations. Results As predicted, we find a substantial association between locus-specific divergence between allopatric populations and locus-specific introgression in admixed populations. However, many loci depart from this relationship, sometimes strongly so. We also report evidence for selection against foreign alleles due to local adaptation. Conclusions Loci that are strongly differentiated between allopatric populations sometimes contribute to reproductive isolation in admixed populations. However, geographic variation in selection and local adaptation, in aspects of genetic architecture (such as organization of genes, recombination rate variation, number and effect size of variants contributing to adaptation, etc.), and in stochastic evolutionary processes such as drift can cause strong differentiation of loci that do not always contribute to reproductive isolation. The results have implications for the theory of ‘genomic islands of speciation’.
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Affiliation(s)
- Patrik Nosil
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder 80303, USA.
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Shell polymorphism in the land-snail Cepaea nemoralis (L.) along a West-East transect in continental Europe. FOLIA MALACOLOGICA 2012. [DOI: 10.2478/v10125-012-0015-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Nosil P, Gompert Z, Farkas TE, Comeault AA, Feder JL, Buerkle CA, Parchman TL. Genomic consequences of multiple speciation processes in a stick insect. Proc Biol Sci 2012; 279:5058-65. [PMID: 22696527 PMCID: PMC3497229 DOI: 10.1098/rspb.2012.0813] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Diverse geographical modes and mechanisms of speciation are known, and individual speciation genes have now been identified. Despite this progress, genome-wide outcomes of different evolutionary processes during speciation are less understood. Here, we integrate ecological and spatial information, mating trials, transplantation data and analysis of 86 130 single nucleotide polymorphisms (SNPs) in eight populations (28 pairwise comparisons) of Timema cristinae stick insects to test the effects of different factors on genomic divergence in a system undergoing ecological speciation. We find patterns consistent with effects of numerous factors, including geographical distance, gene flow, divergence in host plant use and climate, and selection against maladaptive hybridization (i.e. reinforcement). For example, the number of highly differentiated ‘outlier loci’, allele-frequency clines and the overall distribution of genomic differentiation were recognizably affected by these factors. Although host use has strong effects on phenotypic divergence and reproductive isolation, its effects on genomic divergence were subtler and other factors had pronounced effects. The results demonstrate how genomic data can provide new insights into speciation and how genomic divergence can be complex, yet predictable. Future work could adopt experimental, mapping and functional approaches to directly test which genetic regions are affected by selection and determine their physical location in the genome.
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Affiliation(s)
- Patrik Nosil
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80303, USA.
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Domingues VS, Poh YP, Peterson BK, Pennings PS, Jensen JD, Hoekstra HE. Evidence of adaptation from ancestral variation in young populations of beach mice. Evolution 2012; 66:3209-23. [PMID: 23025610 DOI: 10.1111/j.1558-5646.2012.01669.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
To understand how organisms adapt to novel habitats, which involves both demographic and selective events, we require knowledge of the evolutionary history of populations and also selected alleles. There are still few cases in which the precise mutations (and hence, defined alleles) that contribute to adaptive change have been identified in nature; one exception is the genetic basis of camouflaging pigmentation of oldfield mice (Peromyscus polionotus) that have colonized the sandy dunes of Florida's Gulf Coast. To quantify the genomic impact of colonization as well as the signature of selection, we resequenced 5000 1.5-kb noncoding loci as well as a 160-kb genomic region surrounding the melanocortin-1 receptor (Mc1r), a gene that contributes to pigmentation differences, in beach and mainland populations. Using a genome-wide phylogenetic approach, we recovered a single monophyletic group comprised of beach mice, consistent with a single colonization event of the Gulf Coast. We also found evidence of a severe founder event, estimated to have occurred less than 3000 years ago. In this demographic context, we show that all beach subspecies share a single derived light Mc1r allele, which was likely selected from standing genetic variation that originated in the mainland. Surprisingly, we were unable to identify a clear signature of selection in the Mc1r region, despite independent evidence that this locus contributes to adaptive coloration. Nonetheless, these data allow us to reconstruct and compare the evolutionary history of populations and alleles to better understand how adaptive evolution, following the colonization of a novel habitat, proceeds in nature.
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Affiliation(s)
- Vera S Domingues
- Department of Organismic & Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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45
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Non-ecological speciation, niche conservatism and thermal adaptation: how are they connected? ORG DIVERS EVOL 2012. [DOI: 10.1007/s13127-012-0082-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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GALLIGAN TOBYH, DONNELLAN STEPHENC, SULLOWAY FRANKJ, FITCH ALISONJ, BERTOZZI TERRY, KLEINDORFER SONIA. Panmixia supports divergence with gene flow in Darwin’s small ground finch,Geospiza fuliginosa, on Santa Cruz, Galápagos Islands. Mol Ecol 2012; 21:2106-15. [DOI: 10.1111/j.1365-294x.2012.05511.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Puechmaille SJ, Gouilh MA, Piyapan P, Yokubol M, Mie KM, Bates PJ, Satasook C, Nwe T, Bu SSH, Mackie IJ, Petit EJ, Teeling EC. The evolution of sensory divergence in the context of limited gene flow in the bumblebee bat. Nat Commun 2011; 2:573. [PMID: 22146392 PMCID: PMC3247819 DOI: 10.1038/ncomms1582] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 11/02/2011] [Indexed: 01/12/2023] Open
Abstract
The sensory drive theory of speciation predicts that populations of the same species inhabiting different environments can differ in sensory traits, and that this sensory difference can ultimately drive speciation. However, even in the best-known examples of sensory ecology driven speciation, it is uncertain whether the variation in sensory traits is the cause or the consequence of a reduction in levels of gene flow. Here we show strong genetic differentiation, no gene flow and large echolocation differences between the allopatric Myanmar and Thai populations of the world's smallest mammal, Craseonycteris thonglongyai, and suggest that geographic isolation most likely preceded sensory divergence. Within the geographically continuous Thai population, we show that geographic distance has a primary role in limiting gene flow rather than echolocation divergence. In line with sensory-driven speciation models, we suggest that in C. thonglongyai, limited gene flow creates the suitable conditions that favour the evolution of sensory divergence via local adaptation. Populations of the same species living in different habitats can differ in sensory traits driving speciation, but it is not known if this variation limits gene flow. Here, a genetic and acoustic study of the bumblebee bat suggests that geographic distance, instead of echolocation divergence, limits gene flow.
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Affiliation(s)
- Sébastien J Puechmaille
- School of Biology and Environmental Science & UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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Abstract
A prey species using crypsis to avoid predators has the opportunity to evolve polymorphic crypsis when it is being exposed to two (or more) habitats with different backgrounds. Here, we investigate when this phenomenon can occur, in a simulation study with a sexually reproducing prey and a predator that can learn to find hiding prey, represented by an artificial neural network. Initially, the prey is well adapted to one habitat, but tries to expand its range by invading another, different, habitat. This can cause the prey to evolve toward an intermediate phenotype, equally cryptic in both habitats. The prey can also fail in adapting to its new environment, and stay the same. Alternatively, it can evolve polymorphic crypsis. We find that the evolutionary outcome depends on the amount of dispersal between the habitats, with polymorphic crypsis evolving for low dispersal rates, an intermediate phenotype will evolve for intermediate dispersal rates and no adaptation to the new habitat will occur for high dispersal rates. The distribution of phenotypes of the prey will also vary for different dispersal rates, with narrow distributions for low and high dispersal rate and a wide distribution for intermediate dispersal rates.
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Affiliation(s)
- JENNIE HOLMÉR
- Theoretical Ecology, Ecology Building, Lund University, SE-22362 Lund, Sweden
| | - MICHAEL GREEN
- Computational Biology and Biological Physics, Lund University, Sölvegatan 14A, SE-22362 Lund, Sweden
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OŻGO MAŁGORZATA, BOGUCKI ZDZISŁAW. Colonization, stability, and adaptation in a transplant experiment of the polymorphic land snailCepaea nemoralis(Gastropoda: Pulmonata) at the edge of its geographical range. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01732.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Emelianov I, Hernandes-Lopez A, Torrence M, Watts N. Fusion-fission experiments in Aphidius: evolutionary split without isolation in response to environmental bimodality. Heredity (Edinb) 2011; 106:798-807. [PMID: 20924399 PMCID: PMC3083840 DOI: 10.1038/hdy.2010.121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/24/2010] [Accepted: 08/12/2010] [Indexed: 11/09/2022] Open
Abstract
Studying host-based divergence naturally maintained by a balance between selection and gene flow can provide valuable insights into genetic underpinnings of host adaptation and ecological speciation in parasites. Selection-gene flow balance is often postulated in sympatric host races, but direct experimental evidence is scarce. In this study, we present such evidence obtained in host races of Aphidius ervi, an important hymenopteran agent of biological control of aphids in agriculture, using a novel fusion-fission method of gene flow perturbation. In our study, between-race genetic divergence was obliterated by means of advanced hybridisation, followed by a multi-generation exposure of the resulting genetically uniform hybrid swarm to a two-host environment. This fusion-fission procedure was implemented under two contrasting regimes of between-host gene flow in two replicated experiments involving different racial pairs. Host-based genetic fission in response to environmental bimodality occurred in both experiments in as little as six generations of divergent adaptation despite continuous gene flow. We demonstrate that fission recovery of host-based divergence evolved faster and hybridisation-induced linkage disequilibrium decayed slower under restricted (6.7%) compared with unrestricted gene flow, directly pointing at a balance between gene flow and divergent selection. We also show, in four separate tests, that random drift had no or little role in the observed genetic split. Rates and patterns of fission divergence differed between racial pairs. Comparative linkage analysis of these differences is currently under way to test for the role of genomic architecture of adaptation in ecology-driven divergent evolution.
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Affiliation(s)
- I Emelianov
- Plant and Invertebrate Ecology, Rothamsted Research, Harpenden Herts, UK.
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