Phylogenetics of the antopocerus-modified tarsus clade of Hawaiian Drosophila: diversification across the Hawaiian Islands.

Richard T Lapoint,Patrick M O’Grady,Karl N Magnacca,William J Etges

doi:10.1371/journal.pone.0113227

Richard T Lapoint, Patrick M O’Grady + Show 2 more

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https://doi.org/10.1371/journal.pone.0113227

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Abstract

The Hawaiian Drosophilidae radiation is an ecologically and morphologically diverse clade of almost 700 described species. A phylogenetic approach is key to understanding the evolutionary forces that have given rise to this diverse lineage. Here we infer the phylogeny for the antopocerus, modified tarsus and ciliated tarsus (AMC) clade, a lineage comprising 16% (91 of 687 species) of the described Hawaiian Drosophilidae. To improve on previous analyses we constructed the largest dataset to date for the AMC, including a matrix of 15 genes for 68 species. Results strongly support most of the morphologically defined species groups as monophyletic. We explore the correlation of increased diversity in biogeography, sexual selection and ecology on the present day diversity seen in this lineage using a combination of dating methods, rearing records, and distributional data. Molecular dating analyses indicate that AMC lineage started diversifying about 4.4 million years ago, culminating in the present day AMC diversity. We do not find evidence that ecological speciation or sexual selection played a part in generating this diversity, but given the limited number of described larval substrates and secondary sexual characters analyzed we can not rule these factors out entirely. An increased rate of diversification in the AMC is found to overlap with the emergence of multiple islands in the current chain of high islands, specifically Oahu and Kauai.

Highlights

Diversity in the Hawaiian IslandsThe extreme isolation and varied ecological habitats present in the Hawaiian Islands makes this archipelago home to high levels of endemism [1] and a model system for studying diversification
The combined, concatenated analysis was an improvement over single gene phylogenies, with most nodes resolved with high statistical support in both the likelihood and Bayesian analyses (Fig. 2, Fig. S12)
Most species in the antopocerus species group are endemic to the islands of Maui Nui, with the exception of D. cognata, D. kaneshiroi, D. yooni and D. tanythrix and D. arcuata (Oahu, not included in these analyses)

Summary

Introduction

Diversity in the Hawaiian IslandsThe extreme isolation and varied ecological habitats present in the Hawaiian Islands makes this archipelago home to high levels of endemism [1] and a model system for studying diversification. Price and Clague [9] reviewed Hawaiian lineages with estimated colonization and divergence dates and found that most groups arrived in Hawaii immediately following the formation of the current high islands, approximately 5.2 million years ago (mya). Five endemic lineages are inferred to have colonized the Hawaiian archipelago prior to the formation of the current high islands based on current dated phylogenies [10,11,12,13,14]. The Drosophilidae endemic to Hawaii have diversified into two main clades, the Hawaiian Drosophila, or Idiomyia [17], and the genus Scaptomyza (Figure 1). Combined, this lineage contains an estimated 1000 species, of which 687 are currently described [18]. A number of forces, including ecological adaptation [22, 23], sexual selection [26] and allopatric speciation [27], have been implicated in generating the current high level of species diversity in the Hawaiian Drosophilidae

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