Meeting Abstract

47.5  Monday, Jan. 5  Testosterone, social behavior, and ornaments in two recently diverged dark-eyed junco populations ATWELL, J.W.*; WHITTAKER, D.J.; KETTERSON, E.D.; Indiana University; Indiana University; Indiana University jwatwell@indiana.edu

Many studies have confirmed the importance of specific hormones in mediating the expression of ecologically relevant behavior, physiology, and morphology in a wide variety of animals. Far less is known, however, regarding the degree to which hormone-phenotype relationships are predicted to respond in integrated versus independent ways when we look across populations, species, or taxa. For example, few studies have evaluated how changes in the developmental or selective environment experienced by individuals or populations may alter the expression of testosterone [T] and T-associated characteristics such as social behavior, sexual ornamentation, or immune function. Our studies take advantage of a unique colonization event to examine patterns of change in T levels, aggressive and parental behavior, and plumage ornamentation in two divergent populations (one colonist, one ancestral-range) of dark-eyed juncos in S. California. Previous studies have documented reduced male territorial aggression, increased male parental care, and reduced elaboration of sexually selected plumage in the colonist population. Early analyses indicate population-level differences in both the seasonal function and social sensitivity of T expression. We will also present data comparing patterns of hormone-phenotype co-variation within the two populations, and examine patterns of selection on testosterone and T-associated behavior and morphology in each population.