David C. Lahti

Learn More
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)
The village weaverbird, Ploceus cucullatus, lays eggs of an extremely broad range of appearance between individuals. This variation is thought to have evolved as a counteradaptation to brood parasitism by the diederik cuckoo Chrysococcyx caprius. The primary objective of our study was to characterize the relationship between egg appearance and egg rejection(More)
Broad ecological shifts can render previously adaptive traits nonfunctional. It is an open question as to how and how quickly nonfunctional traits decay once the selective pressures that favored them are removed. The village weaverbird (Ploceus cucullatus) avoids brood parasitism by rejecting foreign eggs. African populations have evolved high levels of(More)
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)
Viduids are African finches that are obligate brood parasites, using other species to incubate their eggs and care for their young (Payne 1996, 1997a, b, 1998). Of 20 viduid species, 19 are indigobirds and whydahs in the genus Vidua, and one is the Cuckoo Finch Anomalospiza imberbis. Recent analysis of mtDNA sequence data supports the idea that Anomalospiza(More)
Moral systems require individuals to act in service to their social groups. Despite the human tendency to view moral norms as invariant and constantly deserving of adherence, we vary not only in the moral norms that we espouse but also in the degree to which our behavior reflects those norms. Nevertheless, moral systems exhibit patterns and complexity that(More)