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Early Xanthochorema (Trichoptera, Insecta) radiations in New Caledonia originated on ultrabasic rocks.
Stockholm University, Faculty of Science, Department of Zoology, Systematic Zoology.
Entomology Department, Swedish Museum of Natural History.
Entomology Department, Swedish Museum of Natural History.
2008 (English)In: Molecular Phylogenetics and Evolution, ISSN 1055-7903, E-ISSN 1095-9513, Vol. 48, no 3, 904-17 p.Article in journal (Refereed) Published
Abstract [en]

The toxic and nutrient poor ultrabasic rock substrate covering one-third of New Caledonia greatly influenced on the biogeography and diversity of plants in the island. Studies on the effect of ultrabasic substrate on fauna are almost entirely absent. In this paper we examine whether the diversification of Trichoptera of the New Caledonian endemic genus Xanthochorema Kimmins, 1953 was related to the presence of ultrabasic substrate. The analysis is based on data from a phylogeny derived from DNA sequences of mitochondrial COX1, COX2 and 16S, and nuclear EF1a genes. The study of the relationships between ancestral species and substrate was carried out using dispersal-vicariance analysis and tracing the history of substrate association with ultrabasic and non-ultrabasic distributions representing the terminals in the fully resolved phylogenetic tree. Our results show that (1) the ancestor of all Xanthochorema species was present on ultrabasic substrate, (2) early speciation events were restricted to ultrabasic substrate, (3) younger ancestral species dispersed into non-ultrabasic substrates, and (4) late speciation events were restricted to non-ultrabasic substrate. These results correspond to the hypothesis that New Caledonia once was more extensively covered by ultrabasic rocks than at present.

Place, publisher, year, edition, pages
2008. Vol. 48, no 3, 904-17 p.
Keyword [en]
Trichoptera; Dispersal–vicariance analysis; Tracing distributions; New Caledonia; Ultrabasic rocks; Species radiation; Phylogeny
National Category
Biological Systematics
URN: urn:nbn:se:su:diva-14622DOI: 10.1016/j.ympev.2008.06.006ISI: 000259421300009PubMedID: 18620067OAI: diva2:181142
Available from: 2008-10-15 Created: 2008-10-15 Last updated: 2010-07-06Bibliographically approved
In thesis
1. Diversification on an ancient Darwinian island: Evolutionary history of caddisflies (Trichoptera) and other organisms on New Caledonia
Open this publication in new window or tab >>Diversification on an ancient Darwinian island: Evolutionary history of caddisflies (Trichoptera) and other organisms on New Caledonia
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Islands are either of continental or oceanic origin, and the biota of such islands are a result of vicariance and dispersal, respectively. New Caledonia, in the South Pacific, is a part of former Gondwana, but the origin of its biota is heavily debated. Geological studies show that the island was submerged in the Eocene, and that oceanic crust was obducted onto New Caledonia leaving a thick layer of ultramafic rocks on top of the island. We tested the null hypothesis that New Caledonian biota are a result of old Gondwanan vicariance by fitting diversification models on phylogenies from the literature and calculating the gamma statistic. According to the null hypothesis diversification is gradual over time. If on the other hand the biota are a result of recent dispersal or have survived in refugia we would expect slowing of diversification over time. Based on our results we can reject the null hypothesis of old vicariance for the New Caledonian biota. The caddisfly (Trichoptera) fauna on New Caledonia is exceptionally rich with around 600 species, and more than 99.9% are endemic. Molecular phylogenetic hypotheses for three monophyletic caddisfly radiations, Xanthochorema, Caledopsyche et al. and Agmina, are presented. Age estimates agrees with the geological evidence. Three new species of Xanthochorema are described and more than 63% of the Agmina species are new to science. The ultramafic rock substrate, with high heavy metal concentration, has led to high levels of plant adaptation on New Caledonia. We show that caddisflies adapted early to this substrate and subsequently dispersed to non-ultramafic substrate several times, with significantly fewer dispersal events back to the toxic substrate, indicating that adaptation to ultramafic substrate is required and recolonization is difficult when this adaptation has been lost. Ultramafic substrate and other environmental factors have been important in driving the diversification of New Caledonian caddisflies.

Place, publisher, year, edition, pages
Stockholm: Department of Zoology, Stockholm University, 2010. 35 p.
New Caledonia, Trichoptera, island, biogeography, phylogenetics, DNA, dispersal, vicariance, adaptation, ultramafic, diversification, new species, environmental factors
Research subject
Systematic Zoology
urn:nbn:se:su:diva-41154 (URN)978-91-7447-114-4 (ISBN)
Public defence
2010-10-15, Lilla Hörsalen, Naturhistoriska Riksmuseet, Frescativägen 40, Stockholm, 13:00 (English)
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 5: AcceptedAvailable from: 2010-09-23 Created: 2010-07-05 Last updated: 2010-07-08Bibliographically approved

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Espeland, MarianneJohanson, Kjell Arne
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