Newly forming species that have differentiated in allopatry may evolve numerous barriers that prevent the interbreeding when they come back into contact with each other. The objective of this dissertation is to evaluate some mechanisms of prezygotic reproductive isolation in the D. I begin by evaluating how the evolution of female preferences and male sexual characters lead to reinforcement between Drosophila pseudoobscura and its congener D. In particular, I will evaluate two alternative hypotheses; Preference Evolution and Discrimination Enhancement, to determine how selection reduces hybridization between these sister species.
Wolbachia infection lowers fertile sperm transfer in a moth
Drosophila silvestris - Wikipedia
Postmating but prezygotic PMPZ interactions are increasingly recognized as a potentially important early-stage barrier in the evolution of reproductive isolation. A recent study described a potential example between populations of the same species: single matings between Drosophila montana populations resulted in differential fertilisation success because of the inability of sperm from one population Vancouver to penetrate the eggs of the other population Colorado. As the natural mating system of D. We measured premating isolation in no-choice tests, female fecundity, fertility and egg-to-adult viability after single and double matings as well as second-male paternity success P2. Surprisingly, we found no PMPZ reproductive isolation between the two populations under a competitive setting, indicating no difficulty of sperm from Vancouver males to fertilize Colorado eggs after double matings.
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Metrics details. The biological concept of species stresses the importance of understanding what mechanisms maintain species reproductively isolated from each other. Often such mechanisms are divided into premating and postmating, with the latest being the result of either prezygotic or postzygotic isolation barriers. Drosophila willistoni quechua and Drosophila willistoni willistoni are two subspecies that experience reproductive isolation.
The Hawaiian Drosophila are an iconic example of sequential colonization, adaptive radiation and speciation on islands. Genetic and phenotypic analysis of closely related species pairs that exhibit incomplete reproductive isolation can provide insights into the mechanisms of speciation. Drosophila silvestris from Hawai'i Island and Drosophila planitibia from Maui are two closely related allopatric Hawaiian picture-winged Drosophila that produce sterile F1 males but fertile F1 females, a pattern consistent with Haldane's rule. Backcrossing F1 hybrid females between these two species to parental species gives rise to recombinant males with three distinct sperm phenotypes despite a similar genomic background: motile sperm, no sperm sterile , and immotile sperm.