Title

Social dominance: a behavioral mechanism for resource allocation in crayfish

Date of Award

2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biological Sciences

First Advisor

Paul Moore

Second Advisor

Verner Bingman (Committee Member)

Third Advisor

Sheryl Coombs (Committee Member)

Fourth Advisor

Rex Lowe (Committee Member)

Fifth Advisor

Stephen Vessey (Committee Member)

Abstract

Social dominance is often equated with priority of access to resources and higher relative fitness. But the consequences of dominance are not always readily advantageous for an individual and therefore, testing of such assumptions is needed in order to appropriately characterize mechanisms of resource competition in animal systems. This dissertation examined the ecological consequences of dominance in crayfish. Specifically, the following questions were addressed: is resource allocation determined by dominance and how does the structure of resources in an environment affect dominance relationships? By examining the mechanism of how dominance may allocate resources in groups of crayfish, we can begin to answer questions concerning what environmental selective pressures are shaping social behavior in this system. Shelter acquisition and use was examined in a combination of natural, semi-natural, and laboratory studies in order to observe dominance relationships under ecologically relevant conditions. The work presented here shows that: (1) social status has persisting behavioral consequences with regard to shelter use, which are modulated by social context; (2) dominance relationships influence the spatial distribution of crayfish in natural environments such that dominant individuals possess access to more space; (3) resource use strategies differ depending on social history and these strategies may influence larger scale segregation across habitats; and finally, (4) shelter distribution modulates the extent to which social history and shelter ownership influence the formation of subsequent dominance relationships. Taken together, these results demonstrate that dominance has significant consequences for crayfish resource acquisition and holding. However, a complex picture has been revealed as to the nature of dominance establishment and the potential resource benefits associated with dominance. Dominant crayfish posses control over shelter and space but the likelihood of becoming dominant and the subsequent resource use consequences are largely dependent on social and environmental context.