Browsing by Subject "COLORATION"

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  • Teerikorpi, Pauliina Elisabet; Sirkiä, Paivi Maria; Laaksonen, Toni (2018)
    Environmental shifts may induce sudden reversals in the relative quality or sexual attractiveness of mates (ecological crossovers) leading to non-directional sexual selection. Studies on such ecological crossovers induced by environmental shifts during the nonbreeding season are particularly rare. We studied the interactive effects between nonbreeding conditions and a male white wing patch on the breeding success of breeding pairs and the local survival of females in a migratory passerine population over a 32-year period. After dry winters, females paired with large-patched males were more likely to survive than those paired with small-patched males, and vice versa after moist winters. Moreover, after dry winters, large-patched males succeeded in attracting females that laid large clutches, while small-patched males bred with females that laid small clutches, and vice versa after moist winters. This phenomenon led to a difference in fledgling numbers only during years with dry winters and high precipitation during the breeding season. The selection on this male trait and its signaling value to females thus depended on a complex interaction between conditions both at the nonbreeding and breeding grounds. We show that it is important to consider conditions during the nonbreeding season when examining the effects of sexual ornaments on fitness.
  • Hämäläinen, Liisa; Hoppitt, William; Rowland, Hannah M.; Mappes, Johanna; Fulford, Anthony J.; Sosa, Sebastian; Thorogood, Rose (2021)
    Social transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences. Using artificial prey and a novel approach in statistical analyses of social networks, we find that blue tit (Cyanistes caeruleus) and great tit (Parus major) predators learn about prey defences by watching others. This shifts population preferences rapidly to match changes in prey profitability, and reduces predation pressure from naive predators. Our results may help resolve how costly prey defences are maintained despite influxes of naive juvenile predators, and suggest that accounting for social transmission is essential if we are to understand coevolutionary processes. Many species learn through social transmission, which can alter co-evolutionary selection pressures. Experiments involving artificial prey and social networks show that wild birds can learn about unpalatable food by watching others, which helps explain the persistence of costly prey defences despite influxes of naive juvenile predators.