UC Riverside

Natural selection favors traits that enhance fitness in a species and species occur in habitats for which they have suitable traits. These represent evolutionary and ecological processes respectively. Elucidating the relationships between species life history, ecological traits and environmental attributes is necessary to understand the factors shaping the evolution of traits and to gain a mechanistic understanding of communities so we may be able to predict their responses to environmental change.

In the first chapter, I analyze distribution patterns of a breeding bird community along an elevational gradient to test for distinct associations of traits with environmental variation associated with elevation. Communities in high elevations have species with longer nestling periods and wherein males perform incubation feeding. These patterns are similar to those observed in comparisons across phylogenetically paired taxa and demonstrate that selection pressures across elevational gradients select for similar traits despite phylogenetic histories.

In the second chapter, I analyze relationships between life history, ecological traits and environmental attributes across multiple spatial scales in a breeding bird community distributed in a vegetation type subjected to rapid anthropogenic disturbance in the form of urbanization, agriculture, exotic grass invasion. Disturbance variables were associated with larger body mass, residents, disturbance tolerance. Foraging behaviors such as probing and bark gleaning responded negatively to disturbance and can serve as indicators for future monitoring. Seed eating, ground foraging, rock nesting and gleaning were related positively to disturbance and native vegetation attributes indicating species with these traits may better cope with environmental change.

In the third chapter, I analyzed life history variation in galliforms along elevational gradients to test the hypothesis that high elevation environments select for a trade-off of reduced fecundity and increased investment in offspring quality. I predicted that lack of parental care constraint would result in clutch size not varying across elevations but number of broods raised would be fewer at high elevations. Investment in offspring quality would reflect as variation in egg mass. As predicted, clutch size did not vary and egg mass increased with elevation providing partial support for the hypothesis.