Evolution by natural selection is cool. It is one of the most simple and elegant of scientific ideas, and yet it serves to explain the most complex stuff: life. The unifying principles that tie together my broad research interests are that (1) organisms are adapted to their environments by natural selection (differential reproduction) and that (2) an organism's social environment is a particularly potent selective force. Some of the research projects that my collaborators and I currently have on the go are briefly described below. |
(1) An integrative approach to understanding multiple ornaments. |
Red-billed queleas. Breeding male Red-billed Queleas have two separate color-based signaling systems: 1) complex and independently assorting variability in various plumage features reveals individual identity while 2) unimodally distributed coloration in bare parts (bill, leg, and eye-ring) reveals quality (condition, size and dominance). My ongoing research on this species is directed towards resolving the evolutionary significance of this fascinating communication system. Currently in early stages of development, my research will incorporate observations of and experiments on queleas in both their natural habitat and in captivity. In addition, I will perform laboratory analysis of genetics, pigments, and hormones in order to gain an deep understanding of the mechanistic basis to ornament development in this species. |
(2) Social control of animal ornamentation. |
Zebra finches and house sparrows. Sexually selected ornamentation is well known to be influenced by environmental parameters, however our understanding of the role of the social environement on such traits is quite limited. This is somewhat surprising, because manipulating the social environment in captive birds is quite a straight-forward exercise. Using captive flocks of both zebra finches and house sparrows, the objective of this ongoing research project is to 1) determine how strong an influence changes in social groups can have on ornament expression in these species, and 2) determine the physiological mechanisms whereby any of these changes are brought about. |
(3) The evolution of allometry for sexual size dimorphism. |
Comparative patterns in birds. In 1950 Rensch first described that in groups of related species, sexual size dimorphism is more pronounced in larger species. This widespread and fundamental allometric relationship is now commonly referred to as “Rensch’s rule”. Despite numerous recent studies, we still do not have a general explanation for this allometry. However, a promising hypothesis to explain allometry for sexual size dimorphism is that Rensch’s rule is driven by a correlated evolutionary change in females to directional sexual selection on males. The objective of this ongoing study is thus to 1) evaluate broad-scale patterns of allometry in the birds (class: Aves) and 2) test specific critical predictions of the sexual selection hypothesis, using a database of sexual size dimorphism and life-history traits in over 5300 bird species (pooled together from three different research teams). |
(4) Using digital imaging to score biological coloration. |
R-software package. Using digital photography and imaging software to score animal coloration is becoming increasingly widespread. However there are many pitfalls and difficulties associated with taking useful photos, scoring the color digitally, and anayzing the data appropriately. In collaboration with Dr. Mihai Valcu we have developed a set of standardized methodologies designed to maximize the quality of color data collected using digital imaging. In addition we have developed a software package that we call "ColorZapper" (currently in beta stage) that integrates into the statistical program R and automatically records color parameters from photographs in a variety of different ways. |
(5) Properties of egg coloration: use for recognition vs camouflage. |
Murres, weavers and sandpipers. The colors of eggs show extraordinary inter-specific and, in many species, intra-specific variability. What are the functions of egg coloration in birds? Two commonly cited functions are that it serves as (1) a signal of identity used to discriminate the eggs of the parent from those of brood parasites, and (2) a means of concealing eggs from predators. The theoretically expected properties of signals of identity are different than those of signals of presence, where camouflage is considered a "dishonest" signal of presence (Dale 2006). The objective of this study is to compare and contrast the signal properties measured in the eggs of various species where coloration serves for recognition vs various species where coloration serves for predator avoidence. |