2007 Program Abstracts

 

PHEROMONES AND SEXUAL ATTRACTION IN THE WESTERN CLAWED FROG (XENOPUS TROPICALIS)

 Megan Partyka, Angela L. Schwendiman, Brian T. Searcy, Mike C. Owen, Cody Hurlock,  Thasanee Chantarojwong, Catherine R. Propper

 Amphibians produce pheromones which are known to affect communication and courtship behavior. Previous research has shown that several urodeles use pheromones which attract conspecifics of the opposite sex. In anurans, only a limited number of species have been found to produce sex-attracting pheromones. In those cases, the pheromone was produced by males and attracted conspecific females. We investigated whether the Western Clawed Frog, Xenopus tropicalis, produces pheromones attractive to conspecifics. We assessed attraction using an aquatic Y-maze with two water choices flowing into the ends of each test arm. Specifically male or female frogs were tested in a maze containing water of the (1) opposite sex v. control (the conditioned reverse osmosis water used to house animals), (2) same sex v. control, and a sex preference condition with (3) male v. female water. Females did not respond differently to water that previously contained conspecifics of either sex, and males did not respond to water that previously contained conspecific males. However, males spent significantly more time in the female arm of the maze than the control arm (p=0.0209). When given the choice between males or females, a trend towards males choosing the female arm over the male arm is present (p=0.06). These findings indicate that males do detect water that previously contained a female. Our study is the first to support the hypothesis that anurans may produce female pheromones attractive to males. Further investigation is needed to clarify the role of pheromonal communication in the sexual behavior of X. tropicalis.

Poster also presented at: 

Society for Integrative and Comparative Biology Annual Meeting January 2-6, 2008 San Antonio, TX.

 

TRANSMISSION OF DESCRIPTIVE INFORMATION IN ALARM CALLS OF GUNNISONíS PRAIRIE DOGS (CYNOMYS GUNNISONI)

 Constantine Slobodchikoff, William Briggs, Patricia Dennis, and Anne-Marie Hodge

 The Gunnisonís prairie dog (Cynomys gunnisoni) has been the subject of extensive research on communication and alarm calls.  This species has been shown to transmit information identifying the category to which an approaching predator belongs.  These alarm calls also encode information about physical traits of an individual predator within a specific category.  In the present study, field experiments were conducted on a large colony of C. gunnisoni near Flagstaff, Arizona.  This experiment tested the hypothesis that acoustic components of prairie dog alarm calls correlate to differences in size and shape of experimental stimuli.  Prairie dogs were exposed to simulated predators, and acoustical analyses were performed to detect call components corresponding to different categories of physical characteristics. Here we present evidence supporting the hypothesis that prairie dogs are capable of producing alarm calls which encode information about a simulated predator's relative size and shape.

Poster also presented at: 

Society for Integrative and Comparative Biology Annual Meeting January 2-6, 2008 San Antonio, TX.

 

UNUSUALLY HIGH VARIANCE AT PINYON JAY MICROSATELLITE LOCI

Louis Holmes, Russell Benford, and Russell Balda

 Variance in allelic polymorphism at 8 microsatellite loci is unusually high in pinyon jays compared to other animal species. At least three hypotheses explain this phenomenon. The first hypothesis suggests that there is difference in mutation rates among loci. The second hypothesis suggests that the time that each locus began to mutate was different, and older loci had more opportunity to accumulate diversity than did younger loci. The third hypothesis suggests that microsatellites linked to conserved genes are limited in their potential to diversify. Testing these three hypotheses requires knowledge of the rate of mutation at each locus. Therefore, the goals of this investigation are to determine if mutations are occurring and, if so, at what rate. Mutations were looked for using DNA from 20 parent-offspring triads in 5 nuclear families of jays. Pedigree genotyping on each family was performed, but no mutations were detected. Failure to detect mutations could be caused by an indiscernibly low mutation rate at each locus, or by the limited sample size of the study. To discriminate between these possibilities, future research should increase the sample size of parent-offspring triads and include additional microsatellite loci.

  

BATEMAN GRADIENTS AND ALTERNATIVE MATING STRATEGIES

Katharine M. Saunders and Stephen M. Shuster

 Among the available methods for estimating the intensity of sexual selection, the Bateman gradient is considered one of the most accurate, because it specifically measures the standardized covariance between mate numbers and offspring numbers for members of each sex. Although widely used to compare sex differences in selection intensity, it has yet to be used to examine the covariance between mate numbers and offspring numbers among alternative mating strategies. We allowed marine isopods (Paracerceis sculpta) representing the 3 genetically distinct male morphs in this species to mate from 1 to 5 times, and we allowed females to mate 1, 3 and 5 times. We compared the total number of offspring produced by each mating or sequence of matings using 2-way ANOVA. We found that females gained no additional fitness from mating with multiple males, whereas male fitness increased with increasing mate numbers. There were no significant differences in the Bateman gradients for a-, β- and γ-males, and no significant differences in the fitnesses of a-, β- and γ-males allowed to mate with 1-5 females in succession. In nature, the fitnesses of the 3 morphs are highly variable, apparently due to differences in the availability of receptive females. Our results suggest that differences in mate availability, not differences in sexual competence, are responsible for observed variance in fitness within, and for the equality of fitnesses among, the 3 male morphs in this species.

Poster also presented at: 

Society for Integrative and Comparative Biology Annual Meeting January 2-6, 2008 San Antonio, TX.

  

BRINS FIRE: ONE YEAR POST WILDFIRE AQUATIC COMMUNITY RESPONSE IN OAK CREEK, AZ

Mitchel D. Bern and Joseph P. Shannon

 Wildland fires can influence the heterogeneity and bio-diversity of aquatic ecosystems for extended periods of time.  Between June 18-28 2006 the Brins Mesa Fire burned 4,317 acres within the Oak Creek watershed north of Sedona, AZ.  Large amounts of ash, soil, and burned debris were deposited into Oak Creek by monsoon storms though autumn following the fire.  Oak Creek macroinvertebrate density estimates varied significantly by site and season, with Site 1 having about 40% more during the collection period.  Site 1 macroinvertebrate density varied the least, by about 38% between collections, while Site 2 and Site 3 varied by 93 and 96%, respectively.  Trichoptera and Ephemoptera were abundant at Site 1 and were rare at sites 2 and 3.  In contrast Chironomid (Diptera) densities at Site 2 and 3 were 75% higher compared to Site 1 indicating a compositional response to the fire impacted site.  We have determined that the run-off from the Brins Fire can be detected all the way to the confluence of Oak Creek and the Verde River.  Sustained monitoring is required to fully understand the Brins Fire and Oak Creek ecosystem interaction.  We also suggest that priority be given to the riparian-upland interface (RUI) in order to protect the few riparian and stream communities left in the Southwestern United States. 

Poster also presented at: 

The Climate Change and Ecosystem Impacts Conference at NAU October 29 - November 2, 2007.

Society for Integrative and Comparative Biology Annual Meeting January 2-6, 2008 San Antonio, TX.

  

A NOVEL JAW MECHANISM FACILITATES SCRAPING BEHAVIOR IN HELOSTOMA TEMMINKII

Kelly Walsh, Alice Gibb, Cinnamon Pace

 Intramandibular bending usually involves an additional joint between the dentary and articular in the lower jaw of teleost fish (Konow 2005).  H. temminkii has no articular, so this joint is located between an enlarged angular and dentary (Liem 1967).  H. temminkii uses this joint to protrude its jaws over 180o while scraping algae.  Our study focused on determining if the mechanism of jaw-bending involved rotation of the angular and maxillary torsion.  We filmed live specimens feeding and compared them to manipulated preserved specimens.  Our results showed a maximum gape over 180o was common during feeding, and manipulating the angular and maxillary accounted for 74% of increasing the gape.  Other unusual features of H. temminkii include a tendon attached to the dentary and small teeth embedded in the lip ligaments.  The unique jaws of H. temminkii may allow closer scraping of flat surfaces so they may be able to graze algae that other fish cannot easily scrape.

Poster also presented at: 

Society for Integrative and Comparative Biology Annual Meeting January 2-6, 2008 San Antonio, TX.

ESTROGENIC EFFECTS OF URANIUM IN HUMAN BREAST CANCER CELLS

Gillian Generoso, Stefanie Raymond-Whish, Karen Chase, and Cheryl A. Dyer

 Although it has long been known that uraniumís radioactive properties cause numerous health problems, its role as an endocrine-disrupting chemical has yet to be well understood.  In 1949, scientists Maynard and Hodge established the permanent impact of uranium as an endocrine-disrupting chemical by demonstrating that uranium-exposed female rats resulted in fewer pups and reduced litter numbers.  For my research, I investigated uraniumís ability to mimic the effects of estrogen in human breast cancer cells.  All experiments were tissue culture-based, and for this study, I used the MCF7 human breast cancer cell line and 17β-estradiol, or E2, a form of estrogen that is known to stimulate cell growth and proliferation in human breast cancer cells.  In my first experiment, I grew the cells in regular DMEM media to produce a growth curve and to find the generation time.  In my second experiment, I then exposed the cells to estrogen, uranium, or only media to compare their growth.  The results demonstrated that uranium did elicit estrogenic responses by stimulating cell proliferation.  However, as the findings also show, these responses may depend on the duration of exposure and/or uranium concentration.