Molly R. Morris, Ph.D.

     My research interests are in sexual selection, the evolution of alternative mating strategies, and the evolution of communication.  I have used field studies, laboratory studies, phylogenetic studies, and game theory to address questions concerning the function and evolution of behavior.  Currently I am examining the evolution of a pattern of vertical bars found throughout the genus Xiphophorus (swordtail and platyfish).   I  have found that the bars on males function as a sexual signal that attracts females and deters rival males.  By comparing the responses of males and females of three species, I have hypothesized that the responses of males to the bars have evolved in a more correlated fashion with the signal (bars) than female preference for the bars over the same time period.  I plan to determine if this pattern is more general by examining the responses of males and females to the bars in several species within the genus.  The accuracy of my conclusions about the evolution of the bars and responses to the bars depends on the accuracy of the phylogeny I use.  Theref ore, I am currently working on a revision of the Xiphophor us phylogeny.  I am considering several different published data sets, a large previously unpublished allozyme data set, and some new morphological characters.

     The conclusions of comparative studies that use phylogenies are also critically dependent on how the traits are defined.  I am examining the role of several different components of the bars (bar intensity, bar number, bar width, and bilaterally symmetry of bar number) in sexual selection so that I can better define the bars as a sexual signal. I use videotaped images and video animations to tease apart female preference for very specific components of this visual cue. Finally, I am interested in the application of game theory to studies of the evolution of behavior.  My work in this area has included studies of the evolution of alternative mating strategies, bluffing and communication during aggressive interactions.

Selected References:

• Morris, M.R., Elias, J. A. and Moretz, J. A. (in press) Defining the sexually selected male trait vertical bars in relation to female preference in the swordtail fish Xiphophorus cortezi. Ethology

• Merry, J. W. and Morris, M. R. (2001) Preference for symmetry in swordtail fish. Animal Behavior 61, 477-479.

• Morris, M.R., de Queiroz, K. and Morizot, D. (2001) Phylogenetic relationships among the Northern Swordtails (Xiphophorus) as inferred from allozyme data. Copiea 2001, 65-81.

• Dries, L., Morris, M.R. and Ryan, M. J. (2001) Why are some male pygmy swordtails large? Copeia 2001, 355-364.

• Hoefler, C.H. and Morris, M.R. (1999) A technique for the temporary application and augmentation of pigment patterns in fish. Ethology 105, 431-438.

• Morris, M.R. (1998) Further examination of female preference for vertical bars in swordtails: preference for "no bars" in a species without bars. Journal of Fish Biology, Volume 53 (Supplement A), 56-63.

• Morris, M.R. (1998) Female reference for trait symmetry in addition to trait size in swordtail fish. Proc. Roy. Soc. Lond. 265: 907-911.

• Morris, M.R. and K. Casey (1998) Female swordtail fish prefer symmetrical sexual signal. Animal Behaviour. 55, 33-39