Sexual selection by female choice can shape the evolution of male traits within populations, since the most attractive males experience an increase in fitness through elevated mating success. Speciation by sexual sele...Sexual selection by female choice can shape the evolution of male traits within populations, since the most attractive males experience an increase in fitness through elevated mating success. Speciation by sexual selection occurs when evolution in traits and preferences within populations causes differentiation among populations, such that females in alternative populations prefer sexual signals of their own population relative to others. Differentiated traits and preferences thereby play an active role in limiting gene flow between divergent populations. The effectiveness of differentiated preferences in maintaining differentiated male signals against the homogenizing effects of gene flow across populations will be limited by both the degree to which fe- males can discriminate against non-local males, and the breeding values of traits and preferences. Populations of the Hawaiian cricket Laupala cerasina have diverged in pulse rate, a sexually selected male signal, and female acoustic preference for pulse rate. Gene flow between neighboring populations may be reduced if migrants from sexually diverged populations experience re- duced mating success. We show that females discriminate among divergent songs characteristic of neighboring populations, that differences among populations in song and preference breed true in a common environment, and that mean preferences for each population closely match the mean pulse rates. Divergence in preference was observed only between populations that also dif- fered in song. Along with a striking ability to discriminate slight differences in song, correlated evolution of song and preference within populations could be a mechanism that promotes assortative mating among populations, thereby reducing gene flow, and leading to speciation in Laupala [Current Zoology 58 （3）： 416-425, 2012].展开更多
We conducted sexual selection experiments to produce strains with high and low mating discrimination in females of laboratory strains of Hawaiian Drosophila, D.silvestris, then examined secondary sexual traits of thes...We conducted sexual selection experiments to produce strains with high and low mating discrimination in females of laboratory strains of Hawaiian Drosophila, D.silvestris, then examined secondary sexual traits of these two lines, and compared them with that of standard line. In order to do this, we screened out super-males which mated successfully with females and with high mating records;and poor males which usually could not mate successfully with females and had low mating records. In the meantime,choosy females were also screened out, which almost never responded to males' nuptial dance and were difficult to be mated; but indiscriminate females were on the contrary,which were very ready to accept male's nuptial dance and were very easy to be mated. As a result, by mating supermales with choosy females, we were able to produce the high-line strain; similarly, for the low line, we mated poor males with indiscriminate females and we had a strain that was significantly different from our standard strain within just two generations of selection, i.e., morphological trait differences were measured between the standard strain and the two selected lines, which indicated that mating discrimination has affected secondary sexual traits of the lowline strain significantly: Cilia number on the foretibia of low-line males is significantly different from that of the standard line, which perhaps was the indication of incipient speciation in Hawaiian Drosophila.展开更多
文摘Sexual selection by female choice can shape the evolution of male traits within populations, since the most attractive males experience an increase in fitness through elevated mating success. Speciation by sexual selection occurs when evolution in traits and preferences within populations causes differentiation among populations, such that females in alternative populations prefer sexual signals of their own population relative to others. Differentiated traits and preferences thereby play an active role in limiting gene flow between divergent populations. The effectiveness of differentiated preferences in maintaining differentiated male signals against the homogenizing effects of gene flow across populations will be limited by both the degree to which fe- males can discriminate against non-local males, and the breeding values of traits and preferences. Populations of the Hawaiian cricket Laupala cerasina have diverged in pulse rate, a sexually selected male signal, and female acoustic preference for pulse rate. Gene flow between neighboring populations may be reduced if migrants from sexually diverged populations experience re- duced mating success. We show that females discriminate among divergent songs characteristic of neighboring populations, that differences among populations in song and preference breed true in a common environment, and that mean preferences for each population closely match the mean pulse rates. Divergence in preference was observed only between populations that also dif- fered in song. Along with a striking ability to discriminate slight differences in song, correlated evolution of song and preference within populations could be a mechanism that promotes assortative mating among populations, thereby reducing gene flow, and leading to speciation in Laupala [Current Zoology 58 （3）： 416-425, 2012].
基金supported by the China Scholarship Council(CSC)(2010843314)
文摘We conducted sexual selection experiments to produce strains with high and low mating discrimination in females of laboratory strains of Hawaiian Drosophila, D.silvestris, then examined secondary sexual traits of these two lines, and compared them with that of standard line. In order to do this, we screened out super-males which mated successfully with females and with high mating records;and poor males which usually could not mate successfully with females and had low mating records. In the meantime,choosy females were also screened out, which almost never responded to males' nuptial dance and were difficult to be mated; but indiscriminate females were on the contrary,which were very ready to accept male's nuptial dance and were very easy to be mated. As a result, by mating supermales with choosy females, we were able to produce the high-line strain; similarly, for the low line, we mated poor males with indiscriminate females and we had a strain that was significantly different from our standard strain within just two generations of selection, i.e., morphological trait differences were measured between the standard strain and the two selected lines, which indicated that mating discrimination has affected secondary sexual traits of the lowline strain significantly: Cilia number on the foretibia of low-line males is significantly different from that of the standard line, which perhaps was the indication of incipient speciation in Hawaiian Drosophila.
