Conspecific sperm precedence in sister species of Drosophila with overlapping ranges.

摘要: Barriers to gene flow that act after mating but before fertilization are often overlooked in studies of reproductive isolation. Where species sympatric, such "cryptic" isolating barriers may be important maintaining as distinct entities. Drosophila yakuba and its sister D. santomea have overlapping ranges on the island Sao Tome, off coast West Africa. Previous shown two strongly sexually isolated. However, degree sexual isolation observed laboratory cannot explain low frequency (approximately 1%) hybrids nature. This study identifies further reduce between where they sympatric. First, noncompetitive gametic has evolved santomea: heterospecific matings produce significantly fewer offspring than do conspecific matings. Second, sperm precedence (CSP) occurs when females mate with males. CSP is asymmetrical: not show patterns usage consistent CSP. also differ respect remating propensity first These results suggest competitive contribute santomea.