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The roles of vicariance and isolation by distance in shaping biotic diversification across an ancient archipelago: evidence from a Seychelles caecilian amphibian. BMC Evol Biol 2020; 20:110. [PMID: 32847507 PMCID: PMC7448330 DOI: 10.1186/s12862-020-01673-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 08/12/2020] [Indexed: 11/16/2022] Open
Abstract
Background Island systems offer excellent opportunities for studying the evolutionary histories of species by virtue of their restricted size and easily identifiable barriers to gene flow. However, most studies investigating evolutionary patterns and processes shaping biotic diversification have focused on more recent (emergent) rather than ancient oceanic archipelagos. Here, we focus on the granitic islands of the Seychelles, which are unusual among island systems because they have been isolated for a long time and are home to a monophyletic radiation of caecilian amphibians that has been separated from its extant sister lineage for ca. 65–62 Ma. We selected the most widespread Seychelles caecilian species, Hypogeophis rostratus, to investigate intraspecific morphological and genetic (mitochondrial and nuclear) variation across the archipelago (782 samples from nine islands) to identify patterns and test processes that shaped their evolutionary history within the Seychelles. Results Overall a signal of strong geographic structuring with distinct northern- and southern-island clusters were identified across all datasets. We suggest that these distinct groups have been isolated for ca. 1.26 Ma years without subsequent migration between them. Populations from the somewhat geographically isolated island of Frégate showed contrasting relationships to other islands based on genetic and morphological data, clustering alternatively with northern-island (genetic) and southern-island (morphological) populations. Conclusions Although variation in H. rostratus across the Seychelles is explained more by isolation-by-distance than by adaptation, the genetic-morphological incongruence for affinities of Frégate H. rostratus might be caused by local adaptation over-riding the signal from their vicariant history. Our findings highlight the need of integrative approaches to investigate fine-scale geographic structuring to uncover underlying diversity and to better understand evolutionary processes on ancient, continental islands.
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Portik DM, Blackburn DC, McGuire JA. Macroevolutionary Patterns of Sexual Size Dimorphism Among African Tree Frogs (Family: Hyperoliidae). J Hered 2020; 111:379-391. [DOI: 10.1093/jhered/esaa019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/19/2020] [Indexed: 11/13/2022] Open
Abstract
Abstract
Sexual size dimorphism (SSD) is shaped by multiple selective forces that drive the evolution of sex-specific body size, resulting in male or female-biased SSD. Stronger selection on one sex can result in an allometric body size scaling relationship consistent with Rensch’s rule or its converse. Anurans (frogs and toads) generally display female-biased SSD, but there is variation across clades and the mechanisms driving the evolution of SSD remain poorly understood. We investigated these topics in a diverse family of African treefrogs (Hyperoliidae). Hyperoliids display traits considered rare among amphibians, including sexual dichromatism and protogynous sex change. Using phylogenetic comparative methods, we tested if adult ecology, sexual dichromatism, and sex change were predictors of body size or SSD. We also tested whether hyperoliids displayed allometric interspecific body size scaling relationships. We found a majority of hyperoliid taxa display female-biased SSD, but that adult ecology and sexual dichromatism are poor predictors of sex-specific body size and SSD. Regardless of the groupings analyzed (partitioned by clades or traits), we found support for isometric body size scaling. However, we found that sex change is a significant predictor of SSD variation. Species in the Hyperolius viridiflavus complex, which putatively display this trait, show a significant reduction in SSD and are frequently sexually monomorphic in size. Although protogynous sex change needs to be validated for several of these species, we tentatively propose this trait is a novel mechanism influencing anuran body size evolution. Beyond this association, additional factors that shape the evolution of anuran body size and SSD remain elusive.
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Affiliation(s)
- Daniel M Portik
- California Academy of Sciences, San Francisco, CA
- Museum of Vertebrate Zoology, University of California, Berkeley, CA
| | - David C Blackburn
- Florida Museum of Natural History, University of Florida, Gainesville, FL
| | - Jimmy A McGuire
- Museum of Vertebrate Zoology, University of California, Berkeley, CA
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Rocha S, Perera A, Silva A, Posada D, Harris DJ. Evolutionary history ofTrachylepisskinks in the Seychelles islands: introgressive hybridization, morphological evolution and geographic structure. Biol J Linn Soc Lond 2016. [DOI: 10.1111/bij.12803] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sara Rocha
- CIBIO; Centro de Investigação em Biodiversidade e Recursos Genéticos; Campus Agrário de Vairão; Rua Padre Armando Quintas; 4485-661 Vairão Portugal
- Departamento de Bioquímica; Genética e Inmunología; Facultad de Biología; Universidad de Vigo; Vigo 36310 Spain
| | - Anna Perera
- CIBIO; Centro de Investigação em Biodiversidade e Recursos Genéticos; Campus Agrário de Vairão; Rua Padre Armando Quintas; 4485-661 Vairão Portugal
| | - Andreia Silva
- CIBIO; Centro de Investigação em Biodiversidade e Recursos Genéticos; Campus Agrário de Vairão; Rua Padre Armando Quintas; 4485-661 Vairão Portugal
- Departamento de Biologia; Faculdade de Ciências; Rua do Campo Alegre FC4; 4169-007 Porto Portugal
| | - David Posada
- Departamento de Bioquímica; Genética e Inmunología; Facultad de Biología; Universidad de Vigo; Vigo 36310 Spain
| | - D. James Harris
- CIBIO; Centro de Investigação em Biodiversidade e Recursos Genéticos; Campus Agrário de Vairão; Rua Padre Armando Quintas; 4485-661 Vairão Portugal
- Departamento de Biologia; Faculdade de Ciências; Rua do Campo Alegre FC4; 4169-007 Porto Portugal
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Maddock ST, Day JJ, Nussbaum RA, Wilkinson M, Gower DJ. Evolutionary origins and genetic variation of the Seychelles treefrog, Tachycnemis seychellensis (Duméril and Bibron, 1841) (Amphibia: Anura: Hyperoliidae). Mol Phylogenet Evol 2014; 75:194-201. [PMID: 24555995 PMCID: PMC4101239 DOI: 10.1016/j.ympev.2014.02.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 02/06/2014] [Accepted: 02/08/2014] [Indexed: 11/30/2022]
Abstract
The hyperoliid frog Tachycnemis seychellensis, the only species of its genus, is endemic to the four largest granitic islands of the Seychelles archipelago and is reliant on freshwater bodies for reproduction. Its presence in the Seychelles is thought to be the product of a transoceanic dispersal, diverging from the genus Heterixalus, its closest living relative (currently endemic to Madagascar), between approximately 10-35Ma. A previous study documented substantial intraspecific morphological variation among island populations and also among populations within the largest island (Mahé). To assess intraspecific genetic variation and to infer the closest living relative(s) of T. seychellensis, DNA sequence data were generated for three mitochondrial and four nuclear markers. These data support a sister-group relationship between T. seychellensis and Heterixalus, with the divergence between the two occurring between approximately 11-19Ma based on cytb p-distances. Low levels of genetic variation were found among major mitochondrial haplotype clades of T. seychellensis (maximum 0.7% p-distance concatenated mtDNA), and samples from each of the islands (except La Digue) comprised multiple mitochondrial haplotype clades. Two nuclear genes (rag1 and tyr) showed no variation, and the other two (rho and pomc) lacked any notable geographic structuring, counter to patterns observed within presumably more vagile Seychelles taxa such as lizards. The low levels of genetic variation and phylogeographic structure support an interpretation that there is a single but morphologically highly variable species of Seychelles treefrog. The contrasting genetic and morphological intraspecific variation may be attributable to relatively recent admixture during low sea-level stands, ecophenotypic plasticity, local adaptation to different environmental conditions, and/or current and previously small population sizes. Low genetic phylogeographic structure but substantial morphological variation is unusual within anurans.
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Affiliation(s)
- Simon T Maddock
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK; Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK.
| | - Julia J Day
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK
| | - Ronald A Nussbaum
- Museum of Zoology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109-1079, USA
| | - Mark Wilkinson
- Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, UK; Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK
| | - David J Gower
- Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK
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Cumberlidge N, Daniels SR. Recognition of two new species of freshwater crabs from the Seychelles based on molecular evidence (Potamoidea : Potamonautidae). INVERTEBR SYST 2014. [DOI: 10.1071/is13017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The Afrotropical freshwater crab genus Seychellum is endemic to the granitic Seychelles in the Indian Ocean (Mahé, Silhouette, Praslin, La Digue and Frégate). Here we describe two new cryptic species of Seychellum that represent two evolutionarily separate lineages of a previously monotypic genus. This raises to three the number of species of freshwater crabs known from Seychelles. Each species is endemic to either one island (Silhouette) or to a pair of islands (Mahé and Frégate, or Praslin and La Digue). The three species can be clearly distinguished as separate lineages by DNA analysis, haplotyping and examination of gonopod characters. The recognition of S. silhouette, sp. nov. (endemic to Silhouette) and S. mahefregate, sp. nov. (endemic to Mahé and Frégate) reduces the range of the type species, S. alluaudi (A. Milne-Edwards & Bouvier, 1893) to La Digue and Praslin. Both dispersal and vicariance may have played a role in shaping the present distribution patterns of the Seychellois freshwater crabs.
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Rocha S, Posada D, Harris DJ. Phylogeography and diversification history of the day-gecko genus Phelsuma in the Seychelles islands. BMC Evol Biol 2013; 13:3. [PMID: 23289814 PMCID: PMC3598968 DOI: 10.1186/1471-2148-13-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 12/17/2012] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Lying in a shallow continental shelf cyclically affected by oscillating sea levels since the Miocene, the Seychelles islands are particularly interesting for evolutionary studies. Recent molecular studies are generating an emerging picture of the origin of its biota, yet very little is known regarding their phylogeographic structure or on the factors promoting diversification within the archipelago. Here we aimed to obtain a detailed depiction of the genetic structure and evolution of one of the most widespread vertebrate groups in the archipelago: the day-geckos of the genus Phelsuma. In parallel, we aimed to infer divergence times between species and subspecies, testing a long-standing hypothesis that argues for different time since sympatry between species as the cause of their different morphological differentiation across the archipelago. RESULTS Molecular data corroborated the existence of two main lineages, corresponding to the two currently recognized species. Divergences between species likely date back to the Mio-Pliocene, while more recent, Pleistocenic, divergences are suggested within each species. Populations from outer islands share mtDNA haplotypes with inner island populations, suggesting very recent dispersals (or introductions). We found no evidence of current gene flow between species, but results pointed to the possibility of gene flow between (now allopatric) subspecies. Time estimates suggest a synchronous divergence within each species (between island groups). CONCLUSIONS The geographic patterns of genetic variation agree with previous taxonomic subdivisions within each species and the origin of outer islands populations is clearly tracked. The similar intraspecific divergence time estimates obtained suggest that the differential body-size differentiation between species within each group of islands may be driven by factors other than character displacement proportional to time since sympatry, as previously suggested. These factors could include different habitats/resources available within each island group, niche differentiation and/or character displacement. We also bring again into consideration the hypothesis of body size being influenced by the distribution of native vegetation and social systems within this group, although it remains to be tested. Our results highlight not only the necessity of clarifying the role of ecology and interspecific interactions in this group's morphological diversification and community assemblage, but also the importance of co-evolutionary mechanisms and their importance for appropriate conservation of island biodiversity. Further, we provide a detailed description of the phylogeographic structure of these taxa across these islands, which still remain poorly characterized in this respect.
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Affiliation(s)
- Sara Rocha
- CIBIO-UP, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Vairão 4485-661, Portugal
- Departamento de Biologia, Faculdade de Ciências, Rua do Campo Alegre, Porto FC4 4169-007, Portugal
- Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, Vigo 36310, Spain
| | - David Posada
- CIBIO-UP, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Vairão 4485-661, Portugal
- Departamento de Bioquímica, Genética e Inmunología, Facultad de Biología, Universidad de Vigo, Vigo 36310, Spain
| | - D James Harris
- CIBIO-UP, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Vairão 4485-661, Portugal
- Departamento de Biologia, Faculdade de Ciências, Rua do Campo Alegre, Porto FC4 4169-007, Portugal
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ROCHA SARA, HARRIS DJAMES, POSADA DAVID. Cryptic diversity within the endemic prehensile-tailed geckoUrocotyledon inexpectataacross the Seychelles Islands: patterns of phylogeographical structure and isolation at the multilocus level. Biol J Linn Soc Lond 2011. [DOI: 10.1111/j.1095-8312.2011.01710.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Veith M, Kosuch J, Rödel MO, Hillers A, Schmitz A, Burger M, Lötters S. Multiple evolution of sexual dichromatism in African reed frogs. Mol Phylogenet Evol 2009; 51:388-93. [PMID: 19166951 DOI: 10.1016/j.ympev.2008.12.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 12/23/2008] [Accepted: 12/24/2008] [Indexed: 11/29/2022]
Affiliation(s)
- Michael Veith
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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SCHÄUBLE CHLOES. Variation in body size and sexual dimorphism across geographical and environmental space in the frogs Limnodynastes tasmaniensis and L. peronii. Biol J Linn Soc Lond 2004. [DOI: 10.1111/j.1095-8312.2004.00315.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Vences M, Kosuch J, Glaw F, Bohme W, Veith M. Molecular phylogeny of hyperoliid treefrogs: biogeographic origin of Malagasy and Seychellean taxa and re-analysis of familial paraphyly. J ZOOL SYST EVOL RES 2003. [DOI: 10.1046/j.1439-0469.2003.00205.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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