PHYLOGENETIC ANALYSIS OF BREEDING SITE USE AND ALPHA-AMANITIN TOLERANCE WITHIN THE DROSOPHILA-QUINARIA SPECIES GROUP

Citation
Gs. Spicer et J. Jaenike, PHYLOGENETIC ANALYSIS OF BREEDING SITE USE AND ALPHA-AMANITIN TOLERANCE WITHIN THE DROSOPHILA-QUINARIA SPECIES GROUP, Evolution, 50(6), 1996, pp. 2328-2337
Citations number
68
Categorie Soggetti
Ecology,"Genetics & Heredity
Journal title
ISSN journal
00143820
Volume
50
Issue
6
Year of publication
1996
Pages
2328 - 2337
Database
ISI
SICI code
0014-3820(1996)50:6<2328:PAOBSU>2.0.ZU;2-2
Abstract
The Drosophila quinaria group is unusual within the genus in that it c omprises both mycophagous and nonmycophagous species. DNA sequence dat a from three regions of the mitochondrial genome were used to infer re lationships among four mycophagous species and three that breed on dec aying water plants. Phylogenetic analysis of these species show that b reeding in mushrooms and tolerance of high levels of alpha-amanitin we re the ancestral states within the group. Thus, breeding in decaying w ater plants and intolerance of alpha-amanitin are derived conditions. We also found that the D. quinaria species group does not comprise sep arate mycophagous and nonmycophagous clades, but rather that (1) the s hift from mushrooms to decaying plants occurred on at least two occasi ons; or (2) mycophagy reevolved within a lineage that had previously s hifted to breeding on plants. The correlation between mycophagy and al pha-amanitin tolerance is perfect across the species we have examined, indicating that there is no detectable time lag between an ecological shift to a new breeding site and correlated changes in biochemical ad aptation. The genetic distance between the mycophagous D. recens and t he nonmycophagous D. quinaria indicates that these species split only about 1 M.Y.B.P. In terms of alpha-amanitin tolerance, D. recens and D . quinaria are typical of other ecologically similar species within th e group. Thus, evolutionary changes in alpha-amanitin tolerance can ev idently occur on the order of about 1 million yr. Our data also indica te that, in comparison to other groups of Drosophila, the quinaria spe cies group may be undergoing an adaptive radiation.