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van Riemsdijk I, Arntzen JW, Bucciarelli GM, McCartney-Melstad E, Rafajlović M, Scott PA, Toffelmier E, Shaffer HB, Wielstra B. Two transects reveal remarkable variation in gene flow on opposite ends of a European toad hybrid zone. Heredity (Edinb) 2023; 131:15-24. [PMID: 37106116 PMCID: PMC10313803 DOI: 10.1038/s41437-023-00617-6] [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: 06/06/2022] [Revised: 03/27/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Speciation entails a reduction in gene flow between lineages. The rates at which genomic regions become isolated varies across space and time. Barrier markers are linked to putative genes involved in (processes of) reproductive isolation, and, when observed over two transects, indicate species-wide processes. In contrast, transect-specific putative barrier markers suggest local processes. We studied two widely separated transects along the 900 km hybrid zone between Bufo bufo and B. spinosus, in northern and southern France, for ~1200 RADseq markers. We used genomic and geographic cline analyses to identify barrier markers based on their restricted introgression, and found that some markers are transect-specific, while others are shared between transects. Twenty-six barrier markers were shared across both transects, of which some are clustered in the same chromosomal region, suggesting that their associated genes are involved in reduced gene flow across the entire hybrid zone. Transect-specific barrier markers were twice as numerous in the southern than in the northern transect, suggesting that the overall barrier effect is weaker in northern France. We hypothesize that this is consistent with a longer period of secondary contact in southern France. The smaller number of introgressed genes in the northern transect shows considerably more gene flow towards the southern (B. spinosus) than the northern species (B. bufo). We hypothesize that hybrid zone movement in northern France and hybrid zone stability in southern France explain this pattern. The Bufo hybrid zone provides an excellent opportunity to separate a general barrier effect from localized gene flow-reducing conditions.
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Affiliation(s)
- I van Riemsdijk
- Naturalis Biodiversity Center, Leiden, the Netherlands.
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands.
- Institute for Evolution and Ecology, Plant Evolutionary Ecology, Tübingen University, Tübingen, Germany.
| | - J W Arntzen
- Naturalis Biodiversity Center, Leiden, the Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
| | - G M Bucciarelli
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
- Institute of the Environment, UC Davis, Davis, CA, USA
- Department of Wildlife, Fish, and Conservation Biology, UC Davis, Davis, CA, USA
| | - E McCartney-Melstad
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - M Rafajlović
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
- The Linnaeus Centre for Marine Evolutionary Biology, University of Gothenburg, Gothenburg, Sweden
| | - P A Scott
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- Natural Sciences Collegium, Eckerd College, 4200 54 Ave S, St Petersburg, FL, 33711, USA
| | - E Toffelmier
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - H B Shaffer
- Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA
| | - B Wielstra
- Naturalis Biodiversity Center, Leiden, the Netherlands
- Institute of Biology Leiden, Leiden University, Leiden, the Netherlands
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Arntzen JW. A two-species distribution model for parapatric newts, with inferences on their history of spatial replacement. Biol J Linn Soc Lond 2022. [DOI: 10.1093/biolinnean/blac134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
Related species often engage in abutting or overlapping contact zones with various strengths of interspecific competition. Biotic interactions such as these preclude the registration of the full profile of environmental variables that would describe the otherwise larger species ranges. Here, I advocate to forego full range species distribution modelling and instead focus on the ecography of the contact zone, for example with ‘two-species distribution models’ (TSDMs), in which presence data are contrasted against the background of environmental data. The newts Triturus cristatus and Triturus marmoratus meet in the west of France. A countrywide TSDM suggests that the contact zone of the species is located at a climatic gradient, in line with their north-eastern vs. south-western ranges. The species are also ecologically segregated by elevation and forestation, which is in line with a documented movement of the contact zone caused by hedgerow removal in lowland areas. Hindcasts for the Holocene suggest that the species contact zone was positioned at either the same place as at present or more to the south, depending on the amount of forestation. A forecast under climate warming predicts a fast movement to the north, but this scenario is deemed unrealistic. One reason is that recent habitat loss compromises dispersal and range expansion. Other species pairs to which TSDMs have been applied are listed for comparison.
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Affiliation(s)
- Jan W Arntzen
- Institute of Biology, Leiden University, Sylvius Laboratory , Sylviusweg 72, 2333 BE Leiden , The Netherlands
- Naturalis Biodiversity Center , Darwinweg 2, 2333 CR Leiden , The Netherlands
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3
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Hinneberg H, Bamann T, Geue JC, Foerster K, Thomassen HA, Kupfer A. Truly invasive or simply non‐native? Insights from an artificial crested newt hybrid zone. CONSERVATION SCIENCE AND PRACTICE 2022. [DOI: 10.1111/csp2.12752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Heiko Hinneberg
- University of Applied Forest Sciences Rottenburg Germany
- University of Tübingen, Institute of Evolution and Ecology Tübingen Germany
| | | | - Julia C. Geue
- Umeå University, Department of Ecology and Environmental Sciences Umeå Sweden
| | - Katharina Foerster
- University of Tübingen, Institute of Evolution and Ecology Tübingen Germany
| | - Henri A. Thomassen
- University of Tübingen, Institute of Evolution and Ecology Tübingen Germany
| | - Alexander Kupfer
- Department of Zoology, State Museum of Natural History Stuttgart Stuttgart Germany
- Institute of Biology, University of Hohenheim Stuttgart Germany
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Arntzen JW, Jehle R, Wielstra B. Genetic and morphological data demonstrate hybridization and backcrossing in a pair of salamanders at the far end of the speciation continuum. Evol Appl 2021; 14:2784-2793. [PMID: 34950229 PMCID: PMC8674889 DOI: 10.1111/eva.13312] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 09/05/2021] [Accepted: 10/01/2021] [Indexed: 12/23/2022] Open
Abstract
Deeply diverged yet hybridizing species provide a system to investigate the final stages of the speciation process. We study a hybridizing pair of salamander species-the morphologically and genetically drastically different newts Triturus cristatus and T. marmoratus-with a panel of 32 nuclear and mitochondrial genetic markers. Morphologically identified hybrids are mostly of the F1 generation and mothered by T. cristatus. The sex ratio of the F1 hybrid class is reciprocally skewed, with a preponderance of females in T. cristatus-mothered hybrids and males in T. marmoratus-mothered hybrids. This amounts to the Haldane effect operating in one direction of the cross. Deeper generation hybrids are occasionally produced, possibly including F1 hybrid × backcross hybrid offspring. Interspecific gene flow is low, yet skewed toward T. cristatus. This asymmetry may be caused by hybrid zone movement, with the superseding species being predisposed to introgression. The persisting gene flow between deeply differentiated species supports the notion that full genetic isolation may be selected against. Conversely, published morphological data suggest that introgressive hybridization is detrimental, with digital malformations occurring more frequently in the area of sympatry. Finally, to assist field identification, both within the area of natural range overlap and concerning anthropogenic introductions elsewhere, we document the phenotypical variation of two generations of hybrids compared with both parental species. We suggest that fluctuating range boundaries, ecological segregation, cytonuclear incompatibilities and hybrid breakdown through Bateson-Dobzhansky-Muller incompatibilities all contribute to species integrity, despite incomplete isolation during secondary contact.
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Affiliation(s)
- Jan W. Arntzen
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of BiologyLeiden UniversityLeidenThe Netherlands
| | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
| | - Ben Wielstra
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute of BiologyLeiden UniversityLeidenThe Netherlands
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5
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Velo-Antón G, Lourenço A, Galán P, Nicieza A, Tarroso P. Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander. Sci Rep 2021; 11:9259. [PMID: 33927228 PMCID: PMC8085075 DOI: 10.1038/s41598-021-88349-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/07/2021] [Indexed: 02/02/2023] Open
Abstract
Explicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.
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Affiliation(s)
- Guillermo Velo-Antón
- grid.5808.50000 0001 1503 7226CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão. R. Padre Armando Quintas, 4485-661 Vairão, Portugal ,grid.6312.60000 0001 2097 6738Universidade de Vigo, Grupo de Ecoloxía Animal, Departamento de Ecoloxía e Bioloxía Animal, Torre Cacti (Lab 97), 36310 Vigo, Spain
| | - André Lourenço
- grid.5808.50000 0001 1503 7226CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão. R. Padre Armando Quintas, 4485-661 Vairão, Portugal ,grid.5808.50000 0001 1503 7226Departamento de Biologia da Faculdade de Ciências, Universidade do Porto. Rua Campo Alegre, 4169-007 Porto, Portugal
| | - Pedro Galán
- grid.8073.c0000 0001 2176 8535Grupo de Investigación en Bioloxía Evolutiva (GIBE), Departamento de Bioloxía, Facultade de Ciencias, Universidade da Coruña, Campus da Zapateira, s/n, 15071 A Coruña, Spain
| | - Alfredo Nicieza
- grid.10863.3c0000 0001 2164 6351Departamento de Biologıa de Organismos y Sistemas, Universidad de Oviedo, Oviedo, Spain ,grid.10863.3c0000 0001 2164 6351Unidad Mixta de Investigacion en Biodiversidad (UMIB), CSIC-Universidad de Oviedo-Principado de Asturias, Mieres, Spain
| | - Pedro Tarroso
- grid.5808.50000 0001 1503 7226CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão. R. Padre Armando Quintas, 4485-661 Vairão, Portugal
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López‐Delgado J, van Riemsdijk I, Arntzen JW. Tracing species replacement in Iberian marbled newts. Ecol Evol 2021; 11:402-414. [PMID: 33437438 PMCID: PMC7790658 DOI: 10.1002/ece3.7060] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 10/12/2020] [Accepted: 10/19/2020] [Indexed: 11/25/2022] Open
Abstract
Secondary contact between closely related species can lead to the formation of hybrid zones, allowing for interspecific gene flow. Hybrid zone movement can take place if one of the species possesses a competitive advantage over the other, ultimately resulting in species replacement. Such hybrid zone displacement is predicted to leave a genomic footprint across the landscape in the form of asymmetric gene flow (or introgression) of selectively neutral alleles from the displaced to the advancing species. Hybrid zone movement has been suggested for marbled newts in the Iberian Peninsula, supported by asymmetric gene flow and a distribution relict (i.e., an enclave) of Triturus marmoratus in the range of T. pygmaeus. We developed a panel of nuclear and mitochondrial SNP markers to test for the presence of a T. marmoratus genomic footprint in the Lisbon peninsula, south of the enclave. We found no additional populations of T. marmoratus. Analysis with the software Structure showed no genetic traces of T. marmoratus in T. pygmaeus. A principal component analysis showed some variation within the local T. pygmaeus, but it is unclear if this represents introgression from T. marmoratus. The results may be explained by (a) species replacement without introgressive hybridization and (b) displacement with hybridization followed by the near-complete erosion of the footprint by purifying selection. We predict that testing for a genomic footprint north of the reported enclave would confirm that species replacement in these marbled newts occurred with hybridization.
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Affiliation(s)
- Julia López‐Delgado
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Institute for BiologyLeiden UniversityLeidenThe Netherlands
- Present address:
University of LeedsLeedsUnited Kingdom
| | - Isolde van Riemsdijk
- Naturalis Biodiversity CenterLeidenThe Netherlands
- Present address:
Institute for Evolution and Ecology, Tübingen UniversityLeedsGermany
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7
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Melander SL, Mueller RL. Comprehensive Analysis of Salamander Hybridization Suggests a Consistent Relationship between Genetic Distance and Reproductive Isolation across Tetrapods. COPEIA 2020. [DOI: 10.1643/ch-19-319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Scott Lucas Melander
- Department of Biology, Colorado State University, 251 W Pitkin Street, Fort Collins, Colorado 80523; (SLM) ; and (RLM) . Send reprint requests to SLM
| | - Rachel Lockridge Mueller
- Department of Biology, Colorado State University, 251 W Pitkin Street, Fort Collins, Colorado 80523; (SLM) ; and (RLM) . Send reprint requests to SLM
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8
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Arntzen JW, López‐Delgado J, Riemsdijk I, Wielstra B. A genomic footprint of a moving hybrid zone in marbled newts. J ZOOL SYST EVOL RES 2020. [DOI: 10.1111/jzs.12439] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jan W. Arntzen
- Naturalis Biodiversity Center Leiden The Netherlands
- Institute of Biology Leiden University Leiden The Netherlands
| | - Julia López‐Delgado
- Naturalis Biodiversity Center Leiden The Netherlands
- Institute of Biology Leiden University Leiden The Netherlands
| | - Isolde Riemsdijk
- Naturalis Biodiversity Center Leiden The Netherlands
- Institute of Biology Leiden University Leiden The Netherlands
| | - Ben Wielstra
- Naturalis Biodiversity Center Leiden The Netherlands
- Institute of Biology Leiden University Leiden The Netherlands
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9
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Arntzen JW, van Belkom J. 'Mainland-island' population structure of a terrestrial salamander in a forest-bocage landscape with little evidence for in situ ecological speciation. Sci Rep 2020; 10:1700. [PMID: 32015401 PMCID: PMC6997349 DOI: 10.1038/s41598-020-58551-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 01/09/2020] [Indexed: 12/17/2022] Open
Abstract
Adaptation to different ecological environments can, through divergent selection, generate phenotypic and genetic differences between populations, and eventually give rise to new species. The fire salamander (Salamandra salamandra) has been proposed to represent an early stage of ecological speciation, driven by differential habitat adaptation through the deposition and development of larvae in streams versus ponds in the Kottenforst near Bonn (Germany). We set out to test this hypothesis of ecological speciation in an area different from the one where it was raised and we took the opportunity to explore for drivers of genetic differentiation at a landscape scale. A survey over 640 localities demonstrated the species' presence in ponds and streams across forests, hilly terrain and areas with hedgerows ('bocage'). Genetic variation at 14 microsatellite loci across 41 localities in and around two small deciduous forests showed that salamander effective population sizes were higher in forests than in the bocage, with panmixia in the forests (Fst < 0.010) versus genetic drift or founder effects in several of the small and more or less isolated bocage populations (Fst > 0.025). The system fits the 'mainland-island' metapopulation model rather than indicating adaptive genetic divergence in pond versus stream larval habitats. A reanalysis of the Kottenforst data indicated that microsatellite genetic variation fitted a geographical rather than an environmental axis, with a sharp transition from a western pond-breeding to an eastern, more frequently stream-breeding group of populations. A parallel changeover in mitochondrial DNA exists but remains to be well documented. The data support the existence of a hybrid zone following secondary contact of differentiated lineages, more so than speciation in situ.
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Affiliation(s)
- Jan W Arntzen
- Naturalis Biodiversity Center, Leiden, The Netherlands.
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10
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Mačát Z, Rulík M, Jablonski D, Reiter A, Jeřábková L, Rada S, Mikulíček P. Species-specific habitat preferences do not shape the structure of a crested newt hybrid zone ( Triturus cristatus x T. carnifex). Ecol Evol 2019; 9:12446-12458. [PMID: 31788189 PMCID: PMC6875670 DOI: 10.1002/ece3.5683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 08/31/2019] [Accepted: 09/04/2019] [Indexed: 11/08/2022] Open
Abstract
Reproductive isolation barriers maintain the integrity of species by preventing interspecific gene flow. They involve temporal, habitat or behavioral isolation acting before fertilization, and postzygotic isolation manifested as hybrid mortality or sterility. One of the approaches of how to study reproductive isolation barriers is through the analysis of hybrid zones. In this paper, we describe the structure of a hybrid zone between two crested newt species (Triturus cristatus and T. carnifex) in the southern part of the Czech Republic using morphological, microsatellite, and mitochondrial (mtDNA) markers. Specifically, we tested the hypothesis that the structure of the hybrid zone is maintained by species-specific habitat preferences. Comparing the genetic structure of populations with geographical and ecological parameters, we found that the hybrid zone was structured primarily geographically, with T. cristatus-like populations occurring in the northeast and T. carnifex-like populations in the southwest. Despite T. cristatus tending to occur in deeper ponds and T. carnifex on localities with more shading, the effect of both ecological parameters on the structure of the zone was minimal. Next, we corroborated that T. carnifex individuals and some hybrids possess mtDNA of T. dobrogicus, whose nuclear background was not detected in the studied hybrid zone. Hybridization between T. carnifex and T. dobrogicus (resulting in unidirectional mtDNA introgression) had to predate subsequent formation of the hybrid zone between T. cristatus and T. carnifex. Populations of crested newts in the southern part of the Czech Republic thus represent a genetic mosaic of nuclear and mitochondrial genomes of three species.
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Affiliation(s)
- Zdeněk Mačát
- Department of Ecology and Environmental SciencesPalacky UniversityOlomoucCzech Republic
| | - Martin Rulík
- Department of Ecology and Environmental SciencesPalacky UniversityOlomoucCzech Republic
| | | | | | - Lenka Jeřábková
- Nature Conservation Agency of the Czech RepublicPrahaCzech Republic
| | - Stanislav Rada
- Department of Ecology and Environmental SciencesPalacky UniversityOlomoucCzech Republic
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Cogălniceanu D, Stănescu F, Arntzen JW. Testing the hybrid superiority hypothesis in crested and marbled newts. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12322] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Dan Cogălniceanu
- Faculty of Natural and Agricultural Sciences Ovidius University Constanţa Romania
- Chelonia Romania Bucharest Romania
| | - Florina Stănescu
- Faculty of Natural and Agricultural Sciences Ovidius University Constanţa Romania
- Chelonia Romania Bucharest Romania
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12
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Arntzen JW, Üzüm N, Ajduković MD, Ivanović A, Wielstra B. Absence of heterosis in hybrid crested newts. PeerJ 2018; 6:e5317. [PMID: 30065885 PMCID: PMC6063215 DOI: 10.7717/peerj.5317] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/04/2018] [Indexed: 11/27/2022] Open
Abstract
Relationships between phylogenetic relatedness, hybrid zone spatial structure, the amount of interspecific gene flow and population demography were investigated, with the newt genus Triturus as a model system. In earlier work, a bimodal hybrid zone of two distantly related species combined low interspecific gene flow with hybrid sterility and heterosis was documented. Apart from that, a suite of unimodal hybrid zones in closely related Triturus showed more or less extensive introgressive hybridization with no evidence for heterosis. We here report on population demography and interspecific gene flow in two Triturus species (T. macedonicus and T. ivanbureschi in Serbia). These are two that are moderately related, engage in a heterogeneous uni-/bimodal hybrid zone and hence represent an intermediate situation. This study used 13 diagnostic nuclear genetic markers in a population at the species contact zone. This showed that all individuals were hybrids, with no parentals detected. Age, size and longevity and the estimated growth curves are not exceeding that of the parental species, so that we conclude the absence of heterosis in T. macedonicus-T. ivanbureschi. Observations across the genus support the hypothesis that fertile hybrids allocate resources to reproduction and infertile hybrids allocate resources to growth. Several Triturus species hybrid zones not yet studied allow the testing of this hypothesis.
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Affiliation(s)
| | - Nazan Üzüm
- Department of Biology, Faculty of Arts and Sciences, Adnan Menderes University, Aydin, Turkey
| | - Maja D. Ajduković
- Institute for Biological Research “Siniša Stanković”, University of Belgrade, Belgrade, Serbia
| | - Ana Ivanović
- Naturalis Biodiversity Center, Leiden, The Netherlands
- Institute of Zoology, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Ben Wielstra
- Naturalis Biodiversity Center, Leiden, The Netherlands
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
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13
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Souissi A, Bonhomme F, Manchado M, Bahri-Sfar L, Gagnaire PA. Genomic and geographic footprints of differential introgression between two divergent fish species (Solea spp.). Heredity (Edinb) 2018; 121:579-593. [PMID: 29713088 DOI: 10.1038/s41437-018-0079-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/12/2018] [Accepted: 03/10/2018] [Indexed: 11/09/2022] Open
Abstract
Investigating gene flow between closely related species and its variation across the genome is important to understand how reproductive barriers shape genome divergence before speciation is complete. An efficient way to characterize differential gene flow is to study how the genetic interactions that take place in hybrid zones selectively filter gene exchange between species, leading to heterogeneous genome divergence. In the present study, genome-wide divergence and introgression patterns were investigated between two sole species, Solea senegalensis and Solea aegyptiaca, using restriction-associated DNA sequencing (RAD-Seq) to analyze samples taken from a transect spanning the hybrid zone. An integrative approach combining geographic and genomic clines methods with an analysis of individual locus introgression accounting for the demographic history of divergence was conducted. Our results showed that the two sole species have come into secondary contact postglacially, after experiencing a prolonged period (ca. 1.1 to 1.8 Myrs) of allopatric separation. Secondary contact resulted in the formation of a tension zone characterized by strong reproductive isolation, which only allowed introgression in a limited fraction of the genome. We found multiple evidence for a preferential direction of introgression in the S. aegyptiaca genetic background, indicating a possible recent or ongoing movement of the hybrid zone. Deviant introgression signals found in the opposite direction suggested that S. senegalensis could have possibly undergone adaptive introgression that has not yet spread throughout the entire species range. Our study thus illustrates the varied outcomes of genetic interactions between divergent gene pools that recently met after a long history of divergence.
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Affiliation(s)
- Ahmed Souissi
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France. .,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France. .,Faculté des Sciences de Tunis UR11ES08 Biologie intégrative et écologie évolutive et fonctionnelle des milieux aquatiques, Université de Tunis El Manar, 2092, Tunis, Tunisia.
| | - François Bonhomme
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France.,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France
| | - Manuel Manchado
- IFAPA Centro El Toruño, Junta de Andalucía, Camino Tiro Pichón s/n, 11500, El Puerto de Santa María, Cádiz, Spain
| | - Lilia Bahri-Sfar
- Faculté des Sciences de Tunis UR11ES08 Biologie intégrative et écologie évolutive et fonctionnelle des milieux aquatiques, Université de Tunis El Manar, 2092, Tunis, Tunisia
| | - Pierre-Alexandre Gagnaire
- Université de Montpellier, Place Eugène Bataillon, 34095, Montpellier, France.,CNRS-Institut des Sciences de l'Evolution, UMR5554 UM-CNRS-IRD-EPHE, Station Méditerranéenne de l'Environnement Littoral, 34200, Sète, France
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Arntzen JW, de Vries W, Canestrelli D, Martínez-Solano I. Hybrid zone formation and contrasting outcomes of secondary contact over transects in common toads. Mol Ecol 2017; 26:5663-5675. [PMID: 28752635 DOI: 10.1111/mec.14273] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 07/21/2017] [Accepted: 07/24/2017] [Indexed: 01/05/2023]
Abstract
Much progress in speciation research stems from documenting patterns of morphological and genetic variation in hybrid zones. Contrasting patterns of marker introgression in different sections of the contact can provide valuable insights on the relative importance of various evolutionary mechanisms maintaining species differences in the face of hybridization and gene flow and on hybrid zone temporal and spatial dynamics. We studied species interactions in the common toads Bufo bufo and B. spinosus in France and northwestern Italy using morphological and molecular data from the mitochondrial and nuclear genomes in an extensive survey, including two independent transects west and east of the Alps. At both, we found sharp, coincident and concordant nuclear genetic transitions. However, morphological clines were wider or absent and mtDNA introgression was asymmetric. We discuss alternative, nonexclusive hypotheses about evolutionary processes generating these patterns, including drift, selection, long-distance dispersal and spatial shifts in hybrid zone location and structure. The distribution of intraspecific mtDNA lineages supports a scenario in which B. bufo held a local refugium during the last glacial maximum. Present-day genetic profiles are best explained by an advance of B. spinosus from a nearby Iberian refugium, largely superseding the local B. bufo population, followed by an advance of B. bufo from the Balkans, with prongs north and south of the Alps, driving B. spinosus southwards. A pendulum moving hybrid zone, first northwards and then southwards, explains the wide areas of introgression at either side of the current position of the contact zones.
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Affiliation(s)
- Jan W Arntzen
- Naturalis Biodiversity Center, Leiden, The Netherlands
| | | | - Daniele Canestrelli
- Department of Ecological and Biological Science, Largo dell'Università s.n.c., Viterbo, Italy
| | - Iñigo Martínez-Solano
- Naturalis Biodiversity Center, Leiden, The Netherlands.,Evolution and Development Group, Department of Wetland Ecology, Doñana Biological Station, CSIC, Seville, Spain
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Visser M, de Leeuw M, Zuiderwijk A, Arntzen JW. Stabilization of a salamander moving hybrid zone. Ecol Evol 2016; 7:689-696. [PMID: 28116063 PMCID: PMC5243777 DOI: 10.1002/ece3.2676] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/14/2016] [Indexed: 01/05/2023] Open
Abstract
When related species meet upon postglacial range expansion, hybrid zones are frequently formed. Theory predicts that such zones may move over the landscape until equilibrium conditions are reached. One hybrid zone observed to be moving in historical times (1950–1979) is that of the pond‐breeding salamanders Triturus cristatus and Triturus marmoratus in western France. We identified the ecological correlates of the species hybrid zone as elevation, forestation, and hedgerows favoring the more terrestrial T. marmoratus and pond density favoring the more aquatic T. cristatus. The past movement of the zone of ca. 30 km over three decades has probably been driven by the drastic postwar reduction of the “bocage” hedgerow landscape, favoring T. cristatus over T. marmoratus. No further hybrid zone movement was observed from 1979 to the present. To explain the changing dynamics of the hybrid zone, we propose that it stalled, either because an equilibrium was found at an altitude of ca. 140 m a.s.l. or due to pond loss and decreased population densities. While we cannot rule out the former explanation, we found support for the latter. Under agricultural intensification, ponds in the study area are lost at an unprecedented rate of 5.5% per year, so that remaining Triturus populations are increasingly isolated, hampering dispersal and further hybrid zone movement.
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Affiliation(s)
| | | | | | - Jan W Arntzen
- Naturalis Biodiversity Center Leiden The Netherlands
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