Anthropology - Butler University

Testing the Hotspot Hypothesis of Lek Evolution in the White-Crowned Manakin
Meghan Hennessey & Martin Ventura, Faculty Sponsor: Wendy Tori, Earlham College
In many species males gather to display at traditional sites (i.e., leks) for the purpose of
mating. Females visit these display arenas to assess potential mates, and typically there is high
variance in male mating success. The fact that only a few males sire the majority of offspring
begs the question: why do males gather in leks if by doing so they may risk a decrease in fitness
by allowing direct comparison with competing males?
Several hypotheses have been proposed to explain the evolution of leks. The hotspot hypothesis
suggests that patterns of female movement and dispersion determine where males settle. Males
gather in areas with the highest probability of encountering females (hotspots). To test this
hypothesis, we estimated the home range size of two female White-crowned Manakins by
attaching radio transmitters and conducting telemetry via triangulation within a 100 Ha plot in
the Ecuadorian Amazon. Combining our home range estimates with previous female capture
data (2001-2011), we used Geographic Information Systems to generate a female density
map. Next, we examined whether male territories were located in areas of higher female
densities than expected by chance. To do this, we overlaid the observed male territories on the
female density map and calculated the average number of female home ranges overlapping male
territories. We compared this value against 100 sets of randomly generated territories using a
Monte Carlo simulation. Our findings are discussed in light of what is known about this species.
Unusual Gait Transitions in Elephant Calves
Megan Houchin, Faculty Sponsor: Robert Dale, Butler University
Hoyt and Taylor’s (1981) famous study of locomotion in ponies indicated that as the speed of the
ponies increased, they switched gaits from lateral sequence walk, to trot, then to gallop. This
relationship between speed and gait may be true of most animals, but it does not seem true of
young elephants. I recorded the gaits used by elephant calves during their first year of
life. Using reference points in the elephant yard I was able to calculate the speed of the
elephants when using both the lateral sequence and the trot gaits. These elephants exhibited both
gaits over the same range of speeds. I will describe the range of speeds over which the two gaits
overlapped, and discuss why elephant calves might use two different gaits at the same speed
instead of switching gaits like the ponies in Hoyt and Taylor’s study.
African Elephant Locomotion
Elizabeth Jennings, Faculty Sponsor: Robert Dale, Butler University
For hundreds of years, observers thought that elephants had only one gait. Scientists have only
recently recognized that elephants exhibit several walking patterns. Research on elephant
locomotion is important because of their huge size and their unusual body shape; this research
provides insight into the effects of mass on locomotion. There have been several interesting
studies on the footfall patterns of adult African elephants (Loxodonta africana). The present
study extends this work by examining locomotion in an African elephant calf at the Indianapolis
Zoo. I will collect frame-by-frame observational video data from this calf across a six-month
period (from the calf’s birth, July 20, 2011, to January 2012) and use this information to