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Filters: Tags: Sexual selection (X) > Types: Journal Citation (X)

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We contextually analyzed the song of the Bobolink (Dolichonyx oryzivorus) to examine the role of sexual selection on song versatility. Recordings were obtained as territorial males were randomly presented with a caged male (a conspecific intruder), a caged female (a potential breeding partner), and an empty control cage. Sound spectrograms created from the recordings were analyzed and an index of versatility was calculated for each male in each manipulation so that individual song variation could be compared among behavioral contexts. These analyses suggest that more complex or versatile song production is being selected intersexually, whereas short repetitive song is intrasexually selected. Published in The Condor,...
Body mass is sexually dimorphic and varies seasonally for all 5 species of prairie dogs (Sciuridae: Cynomys), as shown by data from live individuals over a period of 28 years (1974–2001; n = 16,447 body masses). Sexual dimorphism (i.e., body mass of males as percentage of body mass of females) during the breeding season is 105% for black-tailed prairie dogs, 127% for Utah prairie dogs, 131% for Gunnison's prairie dogs, and 136% for white-tailed prairie dogs. Sexual dimorphism is minimal at the end of the breeding season, when exhausted males are thin and early-breeding females are heavy with pregnancy. Sexual dimorphism is maximal at weaning, when rested, well-fed males are heavy and females are emaciated from...
Geographic variation in selection pressures may result in population divergence and speciation, especially if sexual selection varies among populations. Yet spatial variation in targets and intensity of sexual selection is well studied in only a few species. Even more rare are simultaneous studies of multiple populations combining observations from natural settings with controlled behavioral experiments. We investigated how sexual selection varies among populations of the chuckwalla, Sauromalus obesus. Chuckwallas are sexually dimorphic in color, and males vary in coloration among populations. Using field observations and multiple regression techniques, we investigated how sexual selection acts on various male traits...