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Although traditional sexual selection theories for the evolution of ornamental male traits often assume consistency in female preferences for the traits over time, recent theories predict plasticity in female mate preferences and the contribution of plastic female preferences to the maintenance of polymorphism in male sexual ornaments. However, the plasticity of female preferences and its influences on male ornaments are almost unknown in natural populations. Here we examined both the intensity of female preferences and the exaggeration of a male ornament (relative area of orange spots) in a wild population of the guppy (Poecilia reticulata) every few months over a period of 3 years. Results indicated that female preference intensity was negatively correlated with the relative area of orange spots of males. In addition, we found a positive correlation between female preference intensity and the relative area of orange spots of males of their offspring generation. Because the relative area of orange spots of male guppies is a heritable trait, female preferences might have a strong influence on male orange spot size in the next generation. This study provides the first evidence of plastic female preferences depending on the scarcity of males with large ornaments in a natural population. Results of this study imply a possible contribution of female preferences for the maintenance of variation in male ornamentation. 相似文献
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Tomonari Akamatsu Kiyomi Nakamura Ryo Kawabe Seishiro Furukawa Hiromi Murata Akihiro Kawakubo Masayuki Komaba 《Marine Biology》2010,157(8):1879-1887
A number of local populations of finless porpoises (Neophocaena phocaenoides) are widely distributed throughout the warm coastal waters of Asia. The Omura Bay population, consisting of approximately
300 individuals, is the smallest of five populations inhabiting Japanese waters. It is a relatively new population that established
after the global warming that took place approximately 9000 years ago. To observe whether these porpoises appear in the major
corridor to the ocean from Omura Bay, we used acoustic monitoring to record occurrences of finless porpoises from November
2007 to May 2009. A stereo acoustic event recorder recorded the intensity and the sound source direction of biosonar signals,
providing independent traces of sound sources corresponding to each detected animal. A total of 226 individuals were detected
over the 1.5-year monitoring period, of which 76% occurred at night and 73% occurred during March and April. We compared the
presence of porpoises to the Japanese anchovy catch in Omura Bay and the Hario Strait over the same period. Results suggested
that possible reductions in anchovy resources in the bay could attract porpoises to the outside of their normal habitat. In
total, 70% of the porpoise recordings took place when the tidal current was moving out of Omura Bay. Porpoises might follow
the prey that are transported out of the bay due to the strong outbound current. The finless porpoises confined to the bay
might extend their swimming area if prey is available. 相似文献