Patterns in the Local and Regional Dynamics of Moth Populations

Abstract

Qualitative patterns relating species'' local population dynamics, body size, regional distribution and feeding specificity have been documented for a variety of taxa. However, analysis of one data set for a number of these relationship has only been performed for species from the same community. Here, I analyze data for over 300 species of adult moths to determine whether similar patterns are apparent in a group of closely related species drawn from different communities. Such an analysis is valuable in allowing us to relate within and cross-community processes (Gaston and Lawton 1988). The data show several predicted patterns. Strong relationships are found between local population abundance; local population variabilities and regional distribution, the most abundant species being the most variable and occurring at the greatest number of sites. Relationships with body size are much less robust, and are particularly sensitive to the ragne of sizes used. Small species tend to have the most variable populations and also to be the most widely distributed; there is no relationship between abundance and body size. Feeding specificity is negatively correlated with body size, but not consistently with abundance or variability. The robustness of some of the relationships is shown using population data from two geographic regions. I conclude that many of the patterns previously documented both co-occur and interact. Though theoretically body size is plausibly a driving force behind most of them, in practice a central role for this variable is not easily demonstrated.