|Tuesday, April 19th|
10:45 AM - 11:00 AM
Reduction of numbers of ticks and tick-borne diseases has been identified as the most pressing veterinary health concern in continental Africa. The loss of livestock to tick-borne illness is especially devastating in resource-poor pastoral communities. In areas where wild animals and livestock coexist, tick abundances are often very high, and therefore the development of effective treatment plans is necessary. Assessments of tick abundance on live animals are required for management or research purposes, however tick counts on the entire body are time consuming, costly, and stressful to the animal. Here we analyzed Boran cattle and Somali sheep in Northern Tanzania and developed linear regression models wherein only the ticks on one body part need to be counted in order to estimate total-body abundance. These models aid in drastically reducing data collection time and are essential in developing tick management strategies in East Africa.
11:00 AM - 11:15 AM
Heliconius butterflies (Nymphalidae: Heliconiinae) warn predators of their toxicity through a variety of intricate and colorful warning patterns (aposematism). The original study of these butterflies and their aposematic interactions led Henry Walter Bates to develop his theory of mimicry n 1862. As a part of the study abroad program SIT Ecuador: Comparative Ecology and Conservation, I conducted a study of this genus in the Río Zuñag valley in central Ecuador. The primary goals of my study were to obtain an inventory of Heliconius species present in this region, to analyze the distribution and frequencies of these species, and to observe mimicry complexes. In total, 53 individuals across five species of Heliconius were recorded. Furthermore, I identified two mimicry complexes in the Río Zuñag valley. This study provides a comprehensive basis for further investigations involving this genus in Ecuador, primarily in regards to mimicry.
11:15 AM - 11:30 AM
Current work suggests that many lizard populations are experiencing negative impacts from ongoing climate change, possibly mediated through the reduction of time available to accomplish life activities such as foraging and breeding, as a result of warming environmental temperatures. Part of better understanding the mechanisms behind how lizards are impacted by climate change involves estimating how ecologically relevant metrics of performance are affected by temperature. We examined the thermal dependence of sprint speed for two species of African skink about which little is known: Sundevall’s writhing skink (Mochlus sundevalli) and sandfish (Scincus scincus). We acclimatized the lizards to different temperatures, and then used a high speed video system to record lizard sprinting down a linearly demarcated track. Here we present thermal optimal performance curves for these two ecologically distinct African lizard species, which can help inform models of lizard extinction risk in the face of global climate change.
11:30 AM - 11:45 AM
The dichotomous key has been used by biologists to identify organisms for centuries. However, the linear nature of a dichotomous key means that if a data point is missing at any point in the series of questions, accurate identification becomes very unlikely. This limitation can be overcome by the use of multi-access keys: using all available characteristics to narrow down possibilities. While multi-access keys have significant advantages over dichotomous keys, they come with a set of new limitations—from software becoming outdated to restricted accessibility in the field—which hinders their use. I explore both the advantages and disadvantages multi-access keys have with relation to my work in constructing one for the snakes of Central and West Africa, while addressing other fundamental issues in the identification of organisms.
11:45 AM - 12:00 PM
Hummingbirds, some of the smallest and most beautiful birds on the planet, are also surprisingly aggressive. Their high energy requirements necessitate feeding strategies that provide them with the most nectar while expending the least energy. Each hummingbird species exhibits a different foraging strategy that varies with habitat conditions, and some will fight for their food. I observed two communities in the Costa Rican cloud forest in Monteverde, both consisting of the same seven hummingbird species. I hypothesized that, at constantly refilled nectar feeders, each hummingbird species and sex would assume the maximally aggressive foraging strategy that its physiology allowed. Through my observation of the outcome of agonistic interactions, such as fighting and display threats, I constructed dominance hierarchies for the two communities. I qualitatively and quantitatively analyzed the patterns that emerged in order to construct a picture of how tropical hummingbird communities function.