Dynamic selective environments and evolutionary traps in human-dominated landscapes.

Human activities can alter selective environments in ways that can reduce the usefulness of certain ornamental traits as honest signals of individual quality and, in some cases, may create evolutionary traps, where rapid changes in selective environments result in maladaptive behavioral decisions. Using the sexually dichromatic, socially monogamous Northern Cardinal (Cardinalis cardinalis) as a model, we hypothesized that urbanization would erode the relationship between plumage coloration and reproductive success. Because the exotic Amur honeysuckle (Lonicera maackii) provides carotenoids, is a preferred habitat attribute, and increases vulnerability to nest predation, we predicted the presence of an evolutionary trap, whereby the brightest males would achieve the lowest reproductive success.

Anthropogenic resource subsidies decouple predator-prey relationships.

The extent to which resource subsidies affect food web dynamics is poorly understood in anthropogenic landscapes. To better understand how species interactions are influenced by subsidies, we studied breeding birds and nest predators along a rural-to-urban landscape gradient that varied in subsidies provided to generalist predators. We hypothesized that resource subsidies in urban landscapes would decouple predator-prey relationships, as predators switch from natural to anthropogenic foods.

A method for detecting undervalued resources with application to breeding birds.

Anthropogenic changes to ecosystems can decouple habitat selection and quality, a phenomenon well illustrated by ecological traps in which individuals mistakenly prefer low-quality habitats. Less recognized is the possibility that individuals might fail to select high-quality habitat because of the absence of some appropriate cue. This incorrect assessment of resource quality can lead to relatively high-quality resources being undervalued, whereby they support fewer individuals than optimal.

Consumer resource matching in urbanizing landscapes: are synanthropic species over-matching?

Population responses of synanthropic species to urbanization may be explained by the resource-matching rule, which postulates that individuals should distribute themselves according to resource availability. According to the resource-matching rule, urban habitats will contain greater densities if they provide better resources than rural habitats. However, because resource availability is density dependent, individuals in urban areas would ultimately achieve fitness levels comparable to, but no better than, individuals in less urban areas.

Urban flight: understanding individual and population-level responses of Nearctic-Neotropical migratory birds to urbanization.

1. Despite the fact that studies of urban ecology have become commonplace in the literature, ecologists still lack empirical evidence of the underlying mechanisms responsible for relationships between urbanization and animal community structure. In an effort to understand the processes that govern an apparent avoidance of urban landscapes by many Nearctic-Neotropical migratory birds, we examined population- and individual-level responses of the Acadian flycatcher (Empidonax virescens) to urbanization within the landscapes surrounding 35 riparian forest stands in Ohio, USA.