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Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys).
Mol Phylogenet Evol. 2011 May; 59(2):477-88.MP

Abstract

The origin of the terrestrial biota of Madagascar and, especially, the smaller island chains of the western Indian Ocean is relatively poorly understood. Madagascar represents a mixture of Gondwanan vicariant lineages and more recent colonizers arriving via Cenozoic dispersal, mostly from Africa. Dispersal must explain the biota of the smaller islands such as the Comoros and the chain of Mascarene islands, but relatively few studies have pinpointed the source of colonizers, which may include mainland Africa, Asia, Australasia, and Madagascar. The pantropical hermit spiders (genus Nephilengys) seem to have colonized the Indian Ocean island arc stretching from Comoros through Madagascar and onto Mascarenes, and thus offer one opportunity to reveal biogeographical patterns in the Indian Ocean. We test alternative hypotheses on the colonization route of Nephilengys spiders in the Indian Ocean and simultaneously test the current taxonomical hypothesis using genetic and morphological data. We used mitochondrial (COI) and nuclear (ITS2) markers to examine Nephilengys phylogenetic structure with samples from Africa, southeast Asia, and the Indian Ocean islands of Madagascar, Mayotte, Réunion and Mauritius. We used Bayesian and parsimony methods to reconstruct phylogenies and haplotype networks, and calculated genetic distances and fixation indices. Our results suggest an African origin of Madagascar Nephilengys via Cenozoic dispersal, and subsequent colonization of the Mascarene islands from Madagascar. We find strong evidence of gene flow across Madagascar and through the neighboring islands north of it, while phylogenetic trees, haplotype networks, and fixation indices all reveal genetically isolated and divergent lineages on Mauritius and Réunion, consistent with female color morphs. These results, and the discovery of the first males from Réunion and Mauritius, in turn falsify the existing taxonomic hypothesis of a single widespread species, Nephilengys borbonica, throughout the archipelago. Instead, we diagnose three Nephilengys species: Nephilengys livida (Vinson, 1863) from Madagascar and Comoros, N. borbonica (Vinson, 1863) from Réunion, and Nephilengys dodo new species from Mauritius. Nephilengys followed a colonization route to Madagascar from Africa, and on through to the Mascarenes, where it speciated on isolated islands. The related golden orb-weaving spiders, genus Nephila, have followed the same colonization route, but Nephila shows shallower divergencies, implying recent colonization, or a moderate level of gene flow across the archipelago preventing speciation. Unlike their synanthropic congeners, N. borbonica and N. dodo are confined to pristine island forests and their discovery calls for evaluation of their conservation status.

Authors+Show Affiliations

Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Novi trg. 2, P.O. Box 306, SI-1001 Ljubljana, Slovenia. kuntner@gmail.comNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

21316478

Citation

Kuntner, Matjaž, and Ingi Agnarsson. "Biogeography and Diversification of Hermit Spiders On Indian Ocean Islands (Nephilidae: Nephilengys)." Molecular Phylogenetics and Evolution, vol. 59, no. 2, 2011, pp. 477-88.
Kuntner M, Agnarsson I. Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys). Mol Phylogenet Evol. 2011;59(2):477-88.
Kuntner, M., & Agnarsson, I. (2011). Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys). Molecular Phylogenetics and Evolution, 59(2), 477-88. https://doi.org/10.1016/j.ympev.2011.02.002
Kuntner M, Agnarsson I. Biogeography and Diversification of Hermit Spiders On Indian Ocean Islands (Nephilidae: Nephilengys). Mol Phylogenet Evol. 2011;59(2):477-88. PubMed PMID: 21316478.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Biogeography and diversification of hermit spiders on Indian Ocean islands (Nephilidae: Nephilengys). AU - Kuntner,Matjaž, AU - Agnarsson,Ingi, Y1 - 2011/02/21/ PY - 2010/11/08/received PY - 2011/01/19/revised PY - 2011/02/02/accepted PY - 2011/2/15/entrez PY - 2011/2/15/pubmed PY - 2011/8/23/medline SP - 477 EP - 88 JF - Molecular phylogenetics and evolution JO - Mol Phylogenet Evol VL - 59 IS - 2 N2 - The origin of the terrestrial biota of Madagascar and, especially, the smaller island chains of the western Indian Ocean is relatively poorly understood. Madagascar represents a mixture of Gondwanan vicariant lineages and more recent colonizers arriving via Cenozoic dispersal, mostly from Africa. Dispersal must explain the biota of the smaller islands such as the Comoros and the chain of Mascarene islands, but relatively few studies have pinpointed the source of colonizers, which may include mainland Africa, Asia, Australasia, and Madagascar. The pantropical hermit spiders (genus Nephilengys) seem to have colonized the Indian Ocean island arc stretching from Comoros through Madagascar and onto Mascarenes, and thus offer one opportunity to reveal biogeographical patterns in the Indian Ocean. We test alternative hypotheses on the colonization route of Nephilengys spiders in the Indian Ocean and simultaneously test the current taxonomical hypothesis using genetic and morphological data. We used mitochondrial (COI) and nuclear (ITS2) markers to examine Nephilengys phylogenetic structure with samples from Africa, southeast Asia, and the Indian Ocean islands of Madagascar, Mayotte, Réunion and Mauritius. We used Bayesian and parsimony methods to reconstruct phylogenies and haplotype networks, and calculated genetic distances and fixation indices. Our results suggest an African origin of Madagascar Nephilengys via Cenozoic dispersal, and subsequent colonization of the Mascarene islands from Madagascar. We find strong evidence of gene flow across Madagascar and through the neighboring islands north of it, while phylogenetic trees, haplotype networks, and fixation indices all reveal genetically isolated and divergent lineages on Mauritius and Réunion, consistent with female color morphs. These results, and the discovery of the first males from Réunion and Mauritius, in turn falsify the existing taxonomic hypothesis of a single widespread species, Nephilengys borbonica, throughout the archipelago. Instead, we diagnose three Nephilengys species: Nephilengys livida (Vinson, 1863) from Madagascar and Comoros, N. borbonica (Vinson, 1863) from Réunion, and Nephilengys dodo new species from Mauritius. Nephilengys followed a colonization route to Madagascar from Africa, and on through to the Mascarenes, where it speciated on isolated islands. The related golden orb-weaving spiders, genus Nephila, have followed the same colonization route, but Nephila shows shallower divergencies, implying recent colonization, or a moderate level of gene flow across the archipelago preventing speciation. Unlike their synanthropic congeners, N. borbonica and N. dodo are confined to pristine island forests and their discovery calls for evaluation of their conservation status. SN - 1095-9513 UR - https://www.unboundmedicine.com/medline/citation/21316478/Biogeography_and_diversification_of_hermit_spiders_on_Indian_Ocean_islands__Nephilidae:_Nephilengys__ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1055-7903(11)00036-4 DB - PRIME DP - Unbound Medicine ER -