POSTMATING-PREZYGOTIC ISOLATION IS NOT AN IMPORTANT SOURCE OF SELECTION FOR REINFORCEMENT WITHIN AND BETWEEN SPECIES IN DROSOPHILA PSEUDOOBSCURA AND D. PERSIMILIS

Evolution ◽  
2005 ◽  
Vol 59 (5) ◽  
pp. 1039 ◽  
Author(s):  
Patrick D. Lorch ◽  
Maria R. Servedio
Keyword(s):  
Drosophila Pseudoobscura ◽  
Prezygotic Isolation ◽  
Selection For ◽  
Postmating Prezygotic Isolation

scholarly journals Genetic divergence in M. Vetukhiv's experimental populations of Drosophila pseudoobscura 1. Rudiments of sexual isolation

1964 ◽  
Vol 5 (1) ◽  
pp. 150-157 ◽  
Author(s):  
Lee Ehrman
Keyword(s):  
Genetic Divergence ◽  
Sexual Isolation ◽  
Drosophila Pseudoobscura ◽  
Selection For ◽  
Experimental Populations

Weak but statistically significant sexual isolation has been demonstrated among Vetukhiv's six experimental populations of Drosophila pseudoobscura, all originally descended from founders taken from cultures of the same hybrids from four geographic localities. These six populations were maintained separately for almost 4½ years and then tested for the existence of sexual isolation. The sexual isolation has arisen in the absence of any selection for isolation, evidently as a by-product of genetic divergence.

scholarly journals Further evidence for coadaptation in crosses between geographic populations of Drosophila pseudoobscura

1968 ◽  
Vol 12 (3) ◽  
pp. 317-330 ◽  
Author(s):  
Wyatt W. Anderson
Keyword(s):  
Body Size ◽  
Species Difference ◽  
Natural Populations ◽  
Drosophila Pseudoobscura ◽  
Gene Pools ◽  
The Pacific ◽  
Geographic Populations ◽  
High Heritability ◽  
Selection For ◽  
Additional Support

Body size in Drosophila pseudoobscura is a continuously varying character with a high heritability; it is almost certainly related to fitness. Natural populations of D. pseudoobscura from Canada to Mexico have been sampled and found to vary geographically in body size. The geographic variation for the genes determining size is to some extent correlated with the physiographic division of the West. The populations from the Pacific coast have genetically smaller flies than do those from the interior provinces. Experimental populations derived from the samples of seven widely separated natural populations were crossed to yield F1 and F2 hybrid generations. Body size in the F1's varied irregularly, while the F2's showed a consistent ‘breakdown’, the F2's being significantly smaller than their F1 parents. The F1's were significantly less variable than their parents, while the F2's were significantly more variable than their parents of the F1 generation. The natural populations possess coadapted genetic systems, with genes mutually adjusted by selection for favorable interactions. Recombination disrupted the balanced genic complexes to give the F2 breakdown and the increased F2 variability. D. pseudoobscura differs from D. subobscura in showing the effects expected in crosses between coadapted systems. This species difference lends additional support to the hypothesis that the gene pools of these two successful species respond in different ways to environmental variation. The gene pool of D. pseudoobscura is flexible and changes readily, while that of D. subobscura is relatively rigid.

scholarly journals Conflict over fertilization underlies the transient evolution of reinforcement

2020 ◽  
Author(s):  
Catherine A. Rushworth ◽  
Alison M. Wardlaw ◽  
Jeffrey Ross-Ibarra ◽  
Yaniv Brandvain
Keyword(s):  
Genetic Model ◽  
Male Gamete ◽  
Coordination Problem ◽  
Potential Conflict ◽  
Prezygotic Isolation ◽  
Male Gametes ◽  
Geographic Patterns ◽  
The Face ◽  
Postmating Prezygotic Isolation ◽  
Two Populations

ABSTRACTWhen two populations or species hybridize, their offspring often experience reductions in fitness relative to either parental population. The production of low fitness hybrids may be prevented by the evolution of increased prezygotic isolation; a process known as reinforcement. Theoretical challenges to the evolution of reinforcement are generally cast as a coordination problem — e.g., linkage disequilibrium between trait and preference loci is difficult to maintain in the face of recombination. However, the evolution of reinforcement also poses a potential conflict between mates. For example, the opportunity costs to hybridization may differ between the sexes or species. This is particularly likely for postmating prezygotic isolation, as the ability to fertilize both conspecific and heterospecific eggs is beneficial to male gametes, but heterospecific mating may incur a cost for female gametes. Motivated by this problem, we develop a population genetic model of interspecific conflict over reinforcement, inspired by ‘gametophytic factors’, which act as postmating prezygotic barriers among Zea mays subspecies. We demonstrate that this conflict results in the transient evolution of reinforcement – after female preference for a conspecific gamete trait rises to high frequency, male traits adaptively introgress into the other population. Ultimately the male gamete trait fixes in both species, and prezygotic isolation returns to pre-reinforcement levels. We interpret geographic patterns of isolation among Z. mays subspecies in light of these findings, and suggest when and how this conflict can be mediated. Our results suggest that sexual conflict may pose an understudied obstacle to the evolution of reinforcement via postmating prezygotic isolation.

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