Genetic variation associated with adaptive traits in the African forest (Loxodonta cyclotis) and savanna elephant (L. africana) [abstract]

Abstract only availableThere are two species of African elephant, the forest (Loxodonta cyclotis) and savanna elephant (L. africana). The savanna elephant is believed to have diverged from the forest species approximately 2.6 million years ago. The different ecologies of the forest and savanna habitat have produced unique adaptations in both species. Variation in behavior and morphological traits are observed between these species, and they likely possess variation in genes underlying adaptive traits. In particular, genetic variation may have helped the savanna elephant adapt to the direct sunlight of the savanna versus the shade of the canopy, and from a browsing diet in the forest that is poor in iron to a grazing diet that is rich in iron. This type of genetic variation is of great importance since patterns of adaptive variation may help predict future effects of adaptive selection in these species. Future conservation efforts may be tailored to fit the species adaptive needs, promoting their long-term survival. We are comparing sequences of genes believed to underlie adaptive mechanisms in both species to determine whether there is variation. DNA was extracted from 15 savanna elephant blood samples and 15 forest elephant fecal samples. We screened three primers used in other species and chose the IRBP and HFE1 loci for amplification and sequencing in the sampled populations. Sequences for both species were aligned and compared. We found variation at the HFE1 locus between the two species. We are currently establishing homology between the elephant sequence and rhinocerous and horse HFE. Once homology is established, we will investigate the nature of the amino acid changes to determine whether they are likely to affect the function of the protein.McNair Scholars Progra

From Africa to your backyard: Evolutionary expansion of axons to maintain rapid nerve conduction in mammals [abstract]

Faculty Mentor: Michael Garcia, Biological SciencesAbstract only availableMyelination evolved as a mechanism to allow for rapid action potential propagation along relatively small axons.  Myelination results in rapid conduction velocities due to myelin-dependent radial axonal growth and insulation of the axon.   Neurofilaments, the main cytoskeletal component of myelinated axons, are essential for myelin-dependent radial axonal growth.  Additionally, neurofilaments medium (NF-M) and heavy (NF-H) are more heavily phosphorylated on serine residues of the lysine-serine-proline (KSP) repeats in myelinated internodes than in non-myelinated areas of the same axon.  In mouse, loss of NF-M KSP repeats strongly inhibits radial-axonal growth and causes a subsequent decrease in conduction velocity.  My preliminary results suggest a relationship between the axonal length (approximated by species size) and the number of KSP repeats found in NF-M.  Using degenerate primers, I have amplified exon 3 of the NF-M gene from genomic DNA of phylogentically diverse mammals.  Subsequent gel electrophoresis data indicates an increase in the length of exon 3 with an increase in species size.  Through DNA sequence analysis, we are in the process of determining if the increase in length of exon 3 is due to an increase in the number of KSP repeats. As larger mammals evolved, the resulting increase in axonal length would require a compensatory mechanism to maintain rapid conduction velocity.  This evidence suggests that the expansion in the number of KSP repeats in NF-M may be a possible mechanism through which evolution increased axonal diameter as larger animals evolved.  As axonal diameter is one of the key determinants of conduction velocity, larger axonal diameter would, at least, allow for conservation of conduction rates in mammals of differing sizes as is observed in mouse (conduction velocity ~50m/s) and humans (conduction velocity ~50m/s)

The effect of genetic relatedness and diversity on parasite load in the North American raccoon (procyon lotor) [abstract]

Abstract only availableThe influence of genetic relatedness and diversity on parasite transmission and diversity was examined in raccoons (Procyon lotor) from mid-Missouri. Relatedness and diversity of individuals was measured using 12 polymorphic microsatellite loci that were amplified using the polymerase chain reaction (PCR). Fragment analysis was used to determine the alleles of the individuals at each locus. Using the computer analysis program Kinship, relationship probabilities were calculated between individuals and populations. Heterozygosity, internal relatedness, and d2 values were also calculated. Parasite similarity indices did not differ among pairwise comparisons of animals with first order, second order, and no detected relationships. We are currently investigating if correlations exist between ectoparasite or endoparasite loads and heterozygosity, internal relatedness and d2 values. The data generated in this preliminary study will be used in a larger study of patterns of disease/parasite occurrences in artificially aggregating raccoons.Life Sciences Undergraduate Research Opportunity Progra

A comparative study of the feral horses of Shackleford Banks and Assateague Island [abstract]

Abstract only availableFeral horses (Equus caballus) can be found today in isolated barrier island populations along the eastern coast of the United States. Assateague Island stretches for 37 miles along the coasts of Maryland and Virginia and is home to about 160 horses. Shackleford Banks, North Carolina is only about nine miles long, and supports an average of 130 horses. Legend persists that these horses washed ashore from Spanish colonial vessels that had shipwrecked nearby, so they may have some common ancestry. They are managed by the National Park Service for the enjoyment of the public, and also serve as a natural laboratory for developing techniques useful in managing large mammal populations. Natural disasters and diseases can pose a threat to the survivorship of these equids. How to augment decimated populations is a management question of immediate concern. We are performing a comparative study of the two populations to assess their genetic and ecological exchangeability. Dr. Eggert has previously assessed the genetic status of the Assateague Island populations; these data have been used for comparison. I have collected fecal samples from 32 horses on Shackleford Banks, and extracted DNA using the Guanadine Thiocyanate/Silica method of Eggert et al. (2005). We used six microsatellite loci to investigate nuclear genetic variability. Allele sizes were determined in an automated sequencer, and the results were scored using GeneMarker. The two populations exhibit significant differentiation at all six loci. This might suggest that the two are not genetically exchangeable. However, this large genetic distance may simply be a result of the heightened genetic drift common in small populations, and therefore it is important to test for ecological differentiation.A&S Undergraduate Research Mentorshi

Establishing the status of the American black bear in southern Missouri [abstract]

Abstract only availableThe current status of the black bear population in Missouri is largely unknown, as we have little to no information concerning its size, reproductive status and origin. However, evidence suggests that the bear population is increasing and the potential for conflicts between humans and a growing bear population makes it essential to learn more about Missouri's bears, including their origins. We tested the hypothesis that Missouri's bears originate from Arkansas against the hypothesis of a relict population that remained in the state and repopulated. To test this hypothesis, DNA was obtained from three relevant bear populations: southern Missouri bears, northwestern Arkansas bears in the Ozark National Forest, and west-central Arkansas bears in the Ouchita National Forest. Missouri bear DNA was collected using hair samples from snares and blood/tissue samples from nuisance bears and Arkansas bear DNA data was obtained from Don White at the University of Arkansas. At this time, nine Missouri bears have been genotyped at six microsatellite loci and have been compared at those six loci to the Ozark National Forest bears (n=21) and the Ouchita National Forest bears (n=45). Using Structure to assign bears to populations, eight of the nine Missouri bears assigned to the Ozark National Forest population and the remaining bear assigned to the Ouchita National Forest population. This data appears to support our hypothesis that Missouri's bears are likely to have originated from Arkansas. To further test our hypothesis, we are currently genotyping additional Missouri bear hair bear samples (≈10) and collaborating in an ancient DNA study of 200 year old Missouri bears (n=8).Life Sciences Undergraduate Research Opportunity Progra