2001 Program Abstracts

 

FACTORS INFLUENCING THE COLONIZATION OF ARTIFICIAL BREEDING SITES BY MALE ISOPODS

Angela Agosta and Stephen M. Shuster

  Laboratory analysis of animal behavior requires that the performances of lab-reared and field collected individuals are the same under experimental conditions. We investigated this issue in laboratory and field populations of Paracerceis sculpta, a Gulf of California isopod, which breeds in calcareous sponges in nature, as well as artificial sponges in the laboratory. We conducted three sets of experiments.  First, we compared the rates at which lab-reared and field collected males colonized artificial sponges.  We found that the juvenile environment of the animals tested had no affect on colonization rate (R2=0.74 F[2, 12]=12.57, p=0.003). Second, we compared the age of males who colonized and did not colonize sponges. We found no difference in the average cuticular pigmentation scores of colonizing and non-colonizing males (G=14.67, df=3, p<.01). Third, we examined the tendency for lab-reared and field-collected animals to colonize artificial sponges when the physical characteristics of sponges were varied. While males of both types colonized artificial sponges at the same rate, sponge size, sponge complexity, and osculum diameter all increased the number of animals colonizing sponges within 48 hours (G=22.20, df=4, p<.001).  Our results suggest that (1) analysis of this species behavior using laboratory stocks and artificial habitats is justified, (2) the repeatability of these experiments with individuals of different ages is high, and (3) considerable variation in the responses of individuals to the physical characteristics of breeding habitats exists.

 

POSSIBLE SELVES

Dyan Ferraris and Heidi Wayment

  This study investigated the relationships between possible selves, role models, and academic achievement among traditional-aged college women. Specifically, I hypothesized that having an influential positive or negative role model would affect the nature of hoped for and feared academic possible selves in terms of their vividness, perceived control of coming to fruition, and amount of time spent thinking about them. Survey data were collected from 62 traditional-aged college women, and t-tests were conducted to examine relationships. The results indicated there were relationships between both positive and negative role models and the nature hoped for and feared selves. First, participants who reported having a positive role model were more likely to believe that their hoped for selves were likely to come true than participants who did not have a positive role model. Second, participants with a negative role model were more likely to believe that they had control over their hoped for selves coming true. Third, participants who were first generation to go to college in their family were more likely to think about their hoped for selves and these hoped for selves were reported as being more vivid than participants who had college-educated parents. Future research and implications of these data are discussed.

 

SPERM COMPETITION AND TIME INVESTMENT STRATEGIES IN A MARINE ISOPOD, PARACERCEIS SCULPTA HOLMES

Kate Oparowski and Stephen M. Shuster

Sperm competition is defined as any behavior, morphology or physiology associated with copulation, multiple mating by females, or paternity assurance, viewed from both a male and a female perspective.  Male sperm allocation strategies are well known in insects but poorly identified in crustaceans.  We used Paracerceis sculpta, a marine isopod species in which multiple, genetically different male morphs coexist, to investigate male time investment strategies and sperm transfer rates, when males are faced with potential sperm competition and/or the possibility of multiple mates. We exposed territorial (a) males to conditions in which sperm competitors, female reproductive condition and female density were varied in a factorial design. a-males showed no differences in their latency to copulate, in their number of copulation attempts or in their durations of copulation across all treatments. Our results suggest that a -males of the species do not significantly alter their mating behaviors in the situations tested.  Results from the sperm transfer experiments are in progress.

  

CORRELATES OF HYPNOTIZABILITY IN EEG READINGS OF LOW, MODERATE, AND HIGHLY SUSEPTIBLE RIGHT-HANDED FEMALES

Brandy Queen, Emily Vaughan, & Larry Stevens

Twelve right-handed, female subjects were chosen for participation based on handedness and consistent scores on the Stanford Group Hypnotic Susceptibility Scale: Form C and on the Harvard Group Scale of Hypnotic Susceptibility: Form A. The subjects were screened into three categories of hypnotic susceptibility (low, moderate, and high). While listening to a 40-minute tape of various hypnotic conditions, EEG readings were taken from twenty electrode sites on each subjectís scalp with a 24-channel brain cap in order to develop a set of EEG patterns for each group of susceptibility. At this time EEG results are not available.

 

DISTRIBUTION ANALYSIS OF AN INTERTIDAL GASTROPOD

Lance Ratcliff and Mark A. Sturtevant

  Theodoxus luteofasciatus (Neritidae), a small marine gastropod characterized by highly variable shell colors and patterns, is found in abundance in Cholla Bay, Sonora, Mexico.  We performed a survey on the distribution of T. luteofasciatus in different areas of the bay.  The more prevalent densities of population are in sublittoral zones, those areas infrequently uncovered at low tide.  Dead snails are abundant in eulittoral zones, those areas frequently uncovered at low tide.  Cholla Bay is permeated with both zones.  Differences exist in the bay regarding the amount of surface rubble, sandy versus muddy substrate, and water levels.  Our study revealed significant relationships between the mass of rubble and the number of live snails in the bay, as well as frequencies of different colors in various areas of the bay.  We speculate that the latter distribution effects may be due to visual predation.

 

THE EFFECTS OF ACTH ON CORTICOSTERONE AND SF-1 LEVELS IN THE BULLFROG, RANA CATESBEIANA

  Priyanka J. Shah and Catherine R. Propper

  Bullfrogs (Rana catesbeiana) were used as a model system to determine if ACTH induces changes in SF-1. The animals were given an injection of ACTH to simulate glucocorticoid release, and then the hypothalamus, the pituitary, the gonads, and internals were removed and relative SF-1 levels were determined by Western blot analysis. Corticosterone levels were measured in the plasma.