People

Laila Yunes-Jiménez, undergraduate thesis
(Universidad Nacional Autónoma de México)

Thesis project: Why females sing more than males: an analysis of female song in the elaborate monomorphic streak-backed oriole (Icterus pustulatus).
Read more: (English version) (Spanish version)







Diego Hernández-Muciño, undergraduate thesis
(Universidad Nacional Autónoma de México)

Thesis project: Sexual differences in territorial defense in the elaborate monomorphic streak-backed oriole (Icterus pustulatus).
Read more: (English version) (Spanish version)











Jennyfer Femat-Rodriguez, master’s thesis
(Universidad Nacional Autónoma de México)

Master's project: Female territoriality at the nest in the streak-backed oriole (Icterus pustulatus).









América P. García-Muñoz, undergraduate thesis
(Universidad Autónoma del Estado de Morelos)

Thesis project: Motmot leaf-display: male and female agonistic signaling with inedible props during territorial defense in the russet-crowned motmot (Momotus mexicanus).

PAST STUDENTS FROM MEXICAN UNIVERSITIES

Troy Murphy

Assistant Professor, Trinity University
tmurphy@trinity.edu

Research focus: Evolution of communication signals and behaviors in birds, with an emphasis on understanding the evolution and adaptive significance of female ornamentation.

Read more: snapshot of my research program

Please contact me if you are interested in joining the lab.

Tiffany Pham

studied what is invisible to us: the ultraviolet reflectance given off by tail feathers of the Turquoise-browed Motmot. She is testing whether there is a link between tail coloration and physiological condition-- as males and females may have evolved to use coloration to signal their quality as a potential mate. Tiffany is also studying circulating testosterone levels in goldfinches. She is testing whether female bill-coloration, which is known to function as a signal of dominance, positively relates to testosterone, a hormone that mediates aggressive behavior.

Natasha Kopecky

studied whether male mate-choice in fish is influenced by the degree of local male-male competition. She is testing whether male betta fish are more likely to exhibit mate choice, or exhibit more intense mate choice, when a male detects a same-sex competitor near a set of females. Males are not often expected to exhibit mate choice because the cost of lost mating opportunities is dramatic; however, if a male perceives that a competitor may inseminate a female before he does, he may benefit by quickly choosing the mate of greater reproductive value so as to exclude the competitor from mating with her.

© 2006 Troy Murphy

Gus (G.R.) Hoff

is interested in the phenomenon that bettas change color quickly. He is testing whether female bettas exhibit mate preference based on the degree of within-individual color change in males. He hypothesizes that females will benefit by assessing the color of a male over a many-day period, as males that are in poor health will be unlikely to maintain high-levels of coloration for sustained periods. Gus will use two ipad displays to manipulate the color of video recorded males— and will then present videos of two different males to a focal female so that she can choose between them.

Rick Simpson

studied a fascinating geographical pattern of sexual dimorphism in birds: temperate species tend to be highly sexually dichromatic —with ornamented males and drab females— whereas tropical species tend to be ornamented in both males and females. He hypothesizes that although tropical females use ornamentation to signal dominance during territorial defense, that these benefits are reduced in temperate zones where females do not generally defend territories. Rick is interested in understanding the selective forces that favor the reduction in female ornamentation in temperate birds (from ornamented ancestors). He hypothesizes that the distance a species migrates is negatively related to the degree of female ornamentation— because those species that migrate farther should experience greater risk of of being seen by predators.

PAST THESIS RESEARCH STUDENTS

Lucy Cevallos

is studying how dynamic signals are used in communication during mate-choice. She is studying American goldfinch bill color, which changes in dramatically over a few hours. Such dynamic signals have the potential to signal short term condition, and can be used by potential mates to assess how well an individual in buffering current stressors (i.e., infection). Dynamic signals can also be evaluated over the long term, and receivers can better asses overall quality of a potential mate by monitoring how bill color changes over time.  To test whether receivers do this, Lucy first tested whether female mate-choice was based on an immediate snapshot assessment of potential mates-- and she found no evidence of this. She is now testing whether females pay attention to fluctuations in male bill color over three days (in captivity), and whether females base mate-choice on the ability of a male to maintain a colorful bill over this period.

Aparna Gomes

is interested in the evolution of female ornamentation. She is testing two alternative hypotheses for why females express elaborate colors: 1) because females gain adaptive benefits from signaling with coloration, or 2) because females express coloration non-adaptively, as a a result of genetic correlation with the males (i.e., as a by-product of sharing most of their genome with the males). Aparna is trying to separate these alternatives by focusing on the fact that carotenoid-based colors (yellows-reds) are more expensive to use as ornaments than are structural colors (blues-greens).   Using comparative methods, she is looking at species in which males express both carotenoid and structural colors, and she is testing whether the females of these species are less likely to express the costly carotenoid based colors.

Joe West

studied whether female bettas (fighting fish) evaluate the competitive ability of a same-sex conspecific based on the competitor’s success in previous aggressive-contests. Joe is testing whether female fish eavesdrop on aggressive interactions to determine whether competitors are winners ‘dominant’ or losers ‘submissive’. Using female betta fighting fish, Joe is testing whether an eavesdropping female will then base foraging decisions on whether a ‘dominant’ or ‘submissive’ competitor is guarding a food resource.

Lindsey Breier

is interested in betta fish interactions. Lindsey joined the lab to assist with data collection for Tasha’s project.


CURRENT THESIS RESEARCH STUDENTS

Other lab members (non thesis research)

Phil Queller

is interested in the evolution of communication signals that indicate dominance (status signals). Phil’s thesis project asks the question: does crest size of the Black-crested Titmouse (Baeolophus atricristatus) signal dominance and allow individuals with greater crest length access to greater food resources. Phil is outfitting wild titmice with passive integrated transponder (PIT) tags, and monitoring individual feeding rates within an array of seed-feeders outfitted with radio frequency identification (RFID) devices. This setup allows Phil to collect data on feeding events across a large population of titmice. Preliminarily research indicates that male crest length positively relates to the number of foraging events, indicating that birds with longer crests may be using their crest length to signal dominance and gain greater access to these feeders. As a next step, Phil will do an manipulative experiment wherein he reduces the number of available feeders, and he will measure whether crest length predicts access to these dwindling resources.


Phil also has an interest in the honesty enforcing mechanisms underlying female status signals (see paper: Pham et al. 2014)

Matthew Mitts

is studying how female American Goldfinches (Spinus tristus) perceive dominance of a potential competitor based on visual communication signals. Among American Goldfinches, female bill color has been shown to signal status during competitive interactions over food resources (Murphy et al. 2009). Bill color is an unusual type of signal because it is highly dynamic and changes color within a few hours based on current condition or health of the bird. Using aviary based dominance experiments, Matthew is testing whether competitors pay attention to the fluctuations in bill color during contest competition. He hypothesizes that the dynamic nature of this signal may be very important during a contest competition when up to date information on competitors aggressive state can be highly beneficial to receivers.

Sophie Wardle

is studying the link between communication signals of dominance (status signals) and the hormone testosterone, which plays a role in both aggression and the development of secondary sexual characteristics. Sophie is testing whether there is a relationship between testosterone and the phenotypic expression of the female and male crest of the Black-crested Titmouse (Baeolophus atricristatus). Because the Black-crested Titmouse is sexually monomorphic (both sexes have a large black crest), this study adds to the short list of studies describing how testosterone mediates female signal expression. Future work will include aviary-based experiments to assess whether the behavioral use of the crest (i.e., behavioral erection of the crest) relates to both baseline testosterone and the ability of individuals to elevate testosterone, as assessed through hormonal GNRH challenge.

Nathan King

is interested in communication signals and mathematical models of social networks. Nathan worked closely with Phil Queller in the study of Black-crested Titmouse (Baeolophus atricristatus), collecting data in the field and designing a computer program to process feeding data captured by passive integrated transponder (PIT) technology. The results were used to evaluate individual dominance on feeding territories, to construct a social network of titmice according to patterns based on connectivity within feeding groups, and to assess the connectivity of individuals within respective feeding groups to those outside the group. Future research will involve comparing crest length and coloration (a possible signal of status) to measures of connectivity, as computed from network analyses.

Jessica Heppard

is in the process of developing a project to investigate how the dynamic nature of a communication signal can affect mate choice. She hypothesizes that females, when making mate-choice decisions, pay attention to fluctuations in male coloration and that they do not simply assess the current color of a potential mate (i.e., females do not use a snapshot to assess a potential mate). Jessica hypothesizes that females pay attention to a male’s appearance over multiple sampling events, and that females integrate this information into an ‘average’ color for a given male. This hypothesis proposes that this type of assessment would be beneficial to females because only males that are in good health will be able to maintain high-levels of coloration for sustained periods. Jessica is currently piloting this project using the fish the Red Shiner (Cyprinella lutrensis). She is testing whether the breeding coloration of the male of this species fluctuates in the short term. The next step will be to test whether females pay attention to these short-term changes in coloration.