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Leah’s Previous Research…

At Bowdoin College (as a visiting assistant professor in collaboration with Dr. Rick Thompson)

Rapid effects of sex steroids on sensory processing in the goldfish and zebrafish

Short-term variation in testosterone may increase reproductive success by changing how sensory organs and the brain respond to social stimuli. In fish, individuals locate one another by sight and by smell. During the reproductive season, short-term increases in circulating sex steroids may enhance visual and olfactory processes, making it easier for spawning individuals to find one another. Student projects investigated how testosterone impacted male visual and olfactory investigations of reproductive females.

Context-specific effects of neurohormones on social behavior in the goldfish

Vasotocin is an evolutionarily old peptide that plays a conserved role in the modulation of social and sexual behavior in non-mammalian vertebrates. It is evolutionary homologous to vasopressin, a peptide found in mammals, including humans. In the goldfish, vasotocin promotes male withdrawal from other male goldfish via projections to the hindbrain. It is possible that vasotocin promotes male approach to female goldfish via projections to other areas of the brain. Student projects investigated if and how vasotocin might modulate social behavior differently depending on the social context. 

At Indiana University (as a doctoral student with Dr. James Goodson)

Neural mechanisms of seasonal flocking in sparrows

Group size influences many aspects of social behavior, including competition, aggression, and social bonding. In many species, group size varies throughout the year. For example, in seasonally flocking bird species, individuals live in larger groups during the winter than during the summer. My dissertation investigated how neural systems regulate this seasonal shift in group size. Using a comparative approach that compared seasonal variation in neurochemical circuits between species that seasonally flock (the field sparrow and the dark-eyed junco) and species that do not seasonally flock (the song sparrow and the eastern towhee), I found that winter flocking is associated with a winter increase in many elements of multiple neurochemical circuits, including corticotropin-releasing hormone, vasoactive intestinal polypeptide and mesotocin (avian homolog of mammalian oxytocin). To explore how a neurochemical might directly promote grouping, I performed pharmacological manipulations in the seasonally flocking dark-eyed junco. I found that during interactions with familiar individuals, mesotocin shifts neural activity towards areas that promote affiliation (the dorsal lateral septum and the rostral arcopallium) and away from a proposed “social aversion network” (the anterior hypothalamus, ventromedial hypothalamus, and medial extended amygdala). 

At the College of William & Mary (as a masters student with Dr. John Swaddle)

Flexible mate guarding in the Australian zebra finch

While socially-monogamous reproductive pairs are very common in birds, most individuals also engage in regular promiscuous mating outside of their social pairing. Sexual conflict over these “extra-pair fertilizations” has led to the evolution of a variety of paternity assurance strategies, including frequent copulation and mate guarding. Adaptive explanations for mate guarding have tended to focus on fitness consequences for males, but mate guarding is likely also adaptive for females in certain contexts. My masters project explored the costs and benefits of mate guarding (and active participation in being guarded) from both the male and female perspectives. I found that for males, mate guarding intensity is greatest when female opportunity to cheat is high and male opportunity to cheat is low. While females do not appear to flexibly mate guard males, I found evidence that females flexibly participate in being guarded.

See “page 1” to read a bit about projects at Muhlenberg

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