caa a22 4500 465782167 CHVBK 20180323111958.0 cr unu---uuuuu 170327e19900401xx s 000 0 eng 10.1007/BF00178316 doi (NATIONALLICENCE)springer-10.1007/BF00178316 Sexual selection on alleles that determine body size in the swordtail Xiphophorus nigrensis [Elektronische Daten] [Michael Ryan, Diana Hews, William Wagner Jr.] Summary: In a natural population, we document changes in the frequencies of alleles influencing body size and size-correlated alternative male reproductive tactics, and we examine the possible role of sexual selection in producing these changes. Male swordtails (Xiphophorus nigrensis, Rio Choy) exhibit three body size classes (small, intermediate, and large) that primarily derive from allelic variation (s, I, L) at the Y-linked pituitary (P) locus. Some XX individuals are male. They are small and can be fathered either by XX or XY males. We compared the frequencies of Y-linked P alleles across two generations in a natural population. There was a significant decrease in the Y-s genotype relative to Y-I and Y-L genotypes. Laboratory experiments suggest that the disadvantage of Y-s resulted, at least in part, from female preference for larger courting males relative to small chasing males. All larger courting males are of the Y-I or Y-L genotypes. Although the frequency of Y-linked P alleles changed across generations, there was no change in the distribution of male body size classes. The stability of the phenotypic distribution across generations, despite changes in P allele frequencies, was maintained by the production of small XX sons by Y-I and Y-L males. Springer-Verlag, 1990 Ryan Michael Department of Zoology, University of Texas, 78712, Austin, TX, USA aut Hews Diana Department of Zoology, University of Texas, 78712, Austin, TX, USA aut Wagner Jr. William Department of Zoology, University of Texas, 78712, Austin, TX, USA aut Behavioral Ecology and Sociobiology Springer-Verlag 26/4(1990-04-01), 231-237 0340-5443 26:4<231 1990 26 265 https://doi.org/10.1007/BF00178316 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00178316 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ryan Michael Department of Zoology, University of Texas, 78712, Austin, TX, USA aut NATIONALLICENCE 700 1- Hews Diana Department of Zoology, University of Texas, 78712, Austin, TX, USA aut NATIONALLICENCE 700 1- Wagner Jr William Department of Zoology, University of Texas, 78712, Austin, TX, USA aut NATIONALLICENCE 773 0- Behavioral Ecology and Sociobiology Springer-Verlag 26/4(1990-04-01), 231-237 0340-5443 26:4<231 1990 26 265 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer