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Sperm size evolution in Drosophila: inter- and intraspecific analysis.
Dominique Joly1, Abraham Korol, Eviatar Nevo
1Populations, Génétique et Evolution, UPR 9034, CNRS, Avenue de la Terrasse, F-91 198 Gif sur Yvette Cedex, France. joly@pge.cnrs-gif.fr
Genetica
|April 20, 2004
Summary
Sperm length varies significantly within and between species, with Drosophila melanogaster showing more variation than Drosophila simulans, potentially linked to speciation. Environmental factors like drought also influence sperm size in D. melanogaster.
Area of Science:
- Evolutionary biology
- Genetics
- Zoology
Background:
- Sperm competition is well-studied across species, but intraspecific variation in sperm size is less understood.
- Limited studies exist on intraspecific sperm size variation, often with small sample sizes.
Purpose of the Study:
- Investigate within-individual, between-individual, and between-population variation of sperm length.
- Compare sperm length variation in two cosmopolitan species: Drosophila simulans and Drosophila melanogaster.
- Examine the influence of sympatry and allopatry on sperm size divergence.
Main Methods:
- Sperm length measurements were taken for D. simulans and D. melanogaster.
- Analysis included within-individual, between-individual, and between-population variations.
- Species were studied in sympatry (Evolution Canyon) and allopatry.
Main Results:
- Sperm length distributions are distinct between D. simulans (mean 1.121 mm) and D. melanogaster (mean 1.989 mm).
- D. melanogaster exhibits greater variability in sperm length mode than D. simulans.
- D. melanogaster shows a clinal pattern in sperm size related to drought, unlike D. simulans.
Conclusions:
- Sperm size divergence is not affected by sympatry or allopatry.
- Environmental factors, such as drought, differentially impact sperm size in D. melanogaster.
- Sperm length variation may play a role in non-random mating and incipient speciation in D. melanogaster.