Lisa Aschemeier - Does the length of vasopressin 1a receptor gene influence female mate
choice in Microtus ochrogaster? Mentors: Dr. Nancy Solomon and Dr. Brian Keane, Zoology.
The neuropeptide vasopressin is known to regulate social behaviors such as affiliation in mammals. Prairie voles (Microtus ochrogaster) have intraspecific variation in the expression of vasopressin 1a receptor gene (V1aR). Variation in the length of microsatellite DNA within the V1aR gene is associated with variation in socio-behavioral traits within the species. Males expressing longer alleles for the V1aR gene have been observed to contribute more time to paternal care and also show a greater preference toward their partner rather than a strange female relative to males expressing shorter alleles. In this study female prairie voles were given a choice in a choice arean between a male with two longer alleles versus a male with two shorter alleles. Choice was based on the total time the female spent with each male, the total number of visits the female made to each male, the number of matings with each male, and the final placement of the nest material over a 72 hour period. After the 72 hour period all females showed preference toward one of the two males. So far, no significant difference was detected in the variables we measured to suggest females are showing preference toward longer or shorter allele length. This data suggests several possibilities that include: females simply cannot differentiate between the differences in the allele lengths, the allele lengths are not the most important factor driving female mate choice, or there is insufficient power at this point to show female preference.
Peter Sebastian – Selective Foraging and the Functional Response of Pardosa milvina Fed on Differing Diets. Mentor: Dr. Ann Rypstra, Zoology.
There is a common assumption that prey species in general have a balanced nutrient body composition. Therefore, generalist predators, like spiders, should not be selective while foraging. However, recent data for spiders has contradicted this assumption. The goal of this work is to answer whether Pardosa milvina will also show foraging selectivity based on prey quality and also to see if there is a difference in the functional response of Pardosa milvina fed on a high versus low quality diet. The last goal is to then see whether a low or high quality diet is preferred. Three experiments were used to answer these questions. The first compared the functional response of spiders fed varying amounts of low quality fruit flies versus spiders fed varying amounts of high quality fruit flies. The second experiment compared the functional response of spiders pre-fed low quality fruit flies and the given high quality fruit flies versus spiders pre-fed high quality fruit flies and also given high quality fruit flies. The last experiment offered a choice of equal high and low quality fruit flies. In experiment 1 spiders fed low quality diet ingested more than spiders fed high quality diet. In experiment 2 high quality pre-fed spiders killed more fruit flies than low quality pre-fed spiders. In experiment 3 spiders given a choice killed more low quality fruit flies but ate more high quality fruit flies. In experiment 1 the spiders ingested more low quality fruit flies in order to meet its nutrient requirements. In experiment 2 spiders pre-fed high quality diet had a better physiological condition and so were able to be more effective predators. In experiment 3, even though more low quality fruit flies were killed, more energy was put into consuming high quality fruit flies. In conclusion, both spider condition and prey quality will influence the way Pardosa milvina forage. While Pardosa milvina did not selectively kill high quality prey, they then were selective in which prey they consumed after killing. Therefore, this does contradict the assumption that generalist predators should not be selective in prey consumption.
Diane Silcox – Formicidae Use of Invertbrate Carrion. Mentor: Dr. Bruce Steinly, Zoology.
There has been a significant effort over the past 20 years to characterize the structure of arthropod communities associated with vertebrate carrion. A few authors Payne (1965), Johnson (1975) and Cornaby (1974) noted ant appearance very early on carrion, even before flies. Few investigations have concentrated on arthropod consumption of invertebrate carrion. Those authors Seastedt (1981) and Fellers (1982) presented an overview of organisms on invertebrate carrion.
The investigation was conducted at Miami University in Oxford, Ohio during the summer of 2006. The carrion source was cicadas frozen from the 2004 emergence. Cicadas were chosen as the carrion source because they emerge in large numbers periodically, such as in 2004, and provide an enormous food input for terrestrial habitats. Cicadas were placed in trials of 50 cicadas, 5, 1 and a control. A 50cm x 50cm grid was used to randomly place cicadas at the base of a selected tree.
The purpose of this investigation was to establish the utilization of invertebrate carrion by ants. Efforts were centered on determining the amount of time required by ants to locate invertebrate carrion. As well as determining if there is significance in abundance of ants on carrion vs. ants not on carrion.
Experimental random placement of carrion in the field was discovered on average in 3.2 min (1min-24min). High numbers of ants were on cicada carrion post discovery with a mean of 266.4 ants (30 ants-594 ants). Ant abundance on carrion vs. not on carrion had a mean of 82.4% (67% - 94%). Peak recruitment was accomplished within 60 minutes. The ants recruit until they exhausted the food source.
