Chi-Cheng Wat
Ph. D. Student
Department of Biology
Texas A&M University
email: ccwat@neo.tamu.edu

I was a graduate student working with Dr. Molly Cummings in the Integrative Biology Department at the University of Texas. I was mainly interested in how the evolution of visual signals (especially in the content of aggressive signals between males and attraction to females) may differ in different habitat light environments. Meanwhile, I have some preliminary behavioral results on the aggressive signals and female mate choice in one of the northern swordtail species, Xiphophorus nezahualcoyotl.

My preliminary study showed that prior to the establishment of a dominance hierarchy between males in this species, females prefer males with black patches of pigmentation. However, after the dominance hierarchy has been established, females prefer males which are more dominant, regardless of melanation pattern. This is interesting because in this species, it is found that females prefer males with more UV-reflectance (Cummings et al., 2003). In theory, males with patches of black pigmentation may proportionally reflect less UV light than the males with vertical bars. So, one may propose that females may prefer males with vertical bars, but not the ones with black patches. What I found here is a bit contradictory to the previous findings. It also has been shown that males with vertical bars are more aggressive than males without in some other swordtail species ( Morris et al., 1995). Again, what I found here is not in concordance with the previous study.

In Spring 2007, I transferred to Texas A&M University to continue my Ph. D. studies with Dr. Gil Rosenthal as my advisor.