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Variation in Drosophila sensory bristle number at ‘Evolution Canyon’

Published online by Cambridge University Press:  17 February 2003

RICHARD F. LYMAN
Affiliation:
Department of Genetics, Box 7614, North Carolina State University, Raleigh, NC 27695, USA
EVIATAR NEVO
Affiliation:
Institute of Evolution, University of Haifa, Mount Carmel, Haifa 31905, Israel
TRUDY F. C. MACKAY
Affiliation:
Department of Genetics, Box 7614, North Carolina State University, Raleigh, NC 27695, USA

Abstract

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‘Evolution Canyon’ on Mount Carmel, Israel, displays highly contrasting physical and biotic environments on a micro-geographic scale, and is a natural laboratory for investigating genetic responses to variable and extreme environments across species. Samples of Drosophila melanogaster and D. simulans were collected from three sites each on the north- and south-facing slopes of the canyon along altitudinal transects, and one site on the valley floor. Numbers of abdominal and sternopleural sensory bristles were recorded for each of these subpopulations in three thermal environments. In D. simulans, sternopleural bristle number exhibited micro-geographic differentiation between the north- and south-facing slopes, while abdominal bristle number was stable across subpopulations. In D. melanogaster, the magnitudes of the difference in mean sternopleural bristle number between the north- and south-facing slopes and of mean abdominal bristle number along the altitudinal gradients were both conditional on rearing temperature. Thus, the pattern of genetic variation between sites was consistent with underlying heterogeneity of genetic mechanisms for response to the same environmental gradients between traits and sibling species. In contrast, the genetic architecture of bristle number at the level of variation within populations was very similar between species for the same bristle trait, although the two traits differed in the relative contribution of genotype by temperature and genotype by sex interaction.

Type
Research Article
Copyright
© 2002 Cambridge University Press