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Natural populations often experience the weakening or removal of a source of selection that had been important in the maintenance of one or more traits. Here we refer to these situations as 'relaxed selection,' and review recent studies that explore the effects of such changes on traits in their ecological contexts. In a few systems, such as the loss of(More)
  • David C Lahti
  • 2005
Historical introductions of species into new habitats can create rare opportunities to test evolutionary hypotheses, such as the role of natural selection in maintaining traits. This study examines two independent introductions of the African village weaverbird (Ploceus cucullatus) to islands where selection on egg appearance traits is expected to differ(More)
Mating signals of many animal species are difficult to produce and thus should indicate signaler quality. Growing evidence suggests that receivers modulate their behaviour in response to signals with varying performance levels, although little is known about if and how responses are affected by receiver attributes. To explore this topic we conducted two(More)
Although egg color is generally consistent within individual birds and robust to environmental variation, recent evidence suggests a degree of susceptibility to environmental perturbation or modulation of egg color. Most of this variation manifests via the physiology of the laying female, but some direct impacts of the environment on laid eggs have also(More)
Contrary to popular belief, evolution is not necessarily progressive. Indeed, traits are often lost or substantially reduced in the process of evolution. In this article, we present several case studies that can be used in the classroom to illustrate both the ubiquity and diversity of cases of trait loss. Our recently acquired knowledge of genetic and(More)
Learned bird song is influenced by inherited predispositions. The canary is a model system for the interaction of genes and learning on behaviour, especially because some strains have undergone artificial selection for song. In this study, roller canaries (bred for low-pitched songs) and border canaries (whose song is higher pitched, similar to the(More)
David Lahti joined the Biology Department in fall 2009. He is unique in the department not only because of his research field, animal behavior, but because he holds two doctoral degrees: a PhD in Ecology and Evolutionary Biology from the University of Michigan and a PhD in Moral Philosophy and Philosophy of Biology from the Whitefield Institute at Oxford,(More)
Synchronous fleeing (i.e. “dreads” or “panic flights”) is a frequently observed but rarely quantified behaviour in colonial birds. Here we analyse video recordings to assess synchronous fleeing behaviour in a Village Weaver (Ploceus cucullatus) colony. Our results indicate that intrusions by heterospecific avian species are frequent and create significant(More)