The origin of parthenogenesis in the genus Campeloma was investigated by analyzing the karyotypes and oogenesis of numerous populations in Florida and Georgia. The species studied were Campeloma geniculum, C. fluoridense, C. limum, C. parthenum and 4 populations of unnamed parthenogens. Campeloma geniculum and C. floridense are diploid (2n = 28) and reproduction is exclusively sexual. Campeloma limum is also diploid and may reproduce either sexually or parthenogenetically, the latter being predominant. Campeloma parthenum and three other populations of unnamed parthenogens are triploid and parthenogenetic. Parthenogenesis was determined to be apomictic with a single maturation division in both the diploids and triploids. / Diploid parthenogenetic Campeloma in Georgia and Florida are considered to have been derived from diploid sexual ancestors by selection. In contrast, the triploid parthenogens are probably the result of the hybridization of a diploid parthenogen and C. geniculum. The karyotypes of the triploids show evidence of multiple chromosomal rearrangements probably involving C. geniculum chromosomes exclusively. Observed misdivisions could lead to altered karyotypes, as well as loss of genetic material and reduced fecundity for some parthenogenetic females. The karyotypes of parthenogenetic and sexual C. limum are indistinguishable, therefore, there are two different reproductive modes within this species. At least some individuals of C. limum can reproduce either apomictically or meiotically. The karyotype of C. floridense is indistinguishable from that of C. limum, therefore, C. floridense and C. limum may be conspecific. / Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3292. / Major Professor: William H. Heard. / Thesis (Ph.D.)--The Florida State University, 1989.

Newly settled Caribbean spiny lobsters, Panulirus argus, undergo an ontogenetic habitat shift from vegetation (algal phase) to crevice shelters (postalgal phase). I experimentally observed the nocturnal behavior and diurnal shelter choice of juveniles across this size range in the absence and presence of conspecifics. Activity and shelter choice was not influenced by conspecifics during the algal phase. Postalgal phase juveniles, in the presence of conspecifics, were induced to greater locomotory activity and shelter sharing. Conspecifics influence produced an ontogenetic habitat shift at a smaller size. / Den sharing behavior by postalgal spiny lobsters has been postulated as a form of cooperation. I examined four hypotheses of how lobsters might benefit from sharing dens and/or being gregarious. By sharing dens, lobsters may increase survival (H$\sb{\rm A1})$ through group defense against predators, or (H$\sb{\rm A2})$ through group defense against interspecific competitors. By being gregarious, lobsters may increase survival (H$\sb{\rm B3})$ through the dilution effect, or (H$\sb{\rm B4})$ through decreased exposure while searching for shelter (guidepost effect). The first two hypotheses provide a benefit for den sharing and constitute cooperation. The last two hypotheses suggest that den sharing is a coincidence of congregation. Each hypothesis makes specific predictions which I tested by den monitoring field surveys, field manipulations and mesocosm experiments. / I found (1) lobsters did not consistently utilize the most defensible dens nor occupy dens to capacity. (2) Den sharing was not correlated with predator or competitor density, but was positively correlated with conspecific density. (3) Lobsters were more often aggregated at a spatial scale larger than a single den. (4) Lobsters did not have higher survival when sharing dens. (5) Lobsters were not better competitors when sharing dens. (6) Lobsters did not have higher survival with higher conspecific density, but (7) lobsters were able to find dens twice as often and three times faster when conspecifics were present. These results support only the guidepost effect (H$\sb{\rm B4})$ hypothesis. Den sharing is a non-advantageous outcome of gregariousness but is not cooperation during the ontogenetic phase when the behavior is first observed. / Source: Dissertation Abstracts International, Volume: 56-12, Section: B, page: 6513. / Major Professor: William F. Herrnkind. / Thesis (Ph.D.)--The Florida State University, 1995.

The structural complexity of a habitat dictates the availability of shelter, and shelter may affect population and community structure in many systems. I test a specific hypothesis of the effects of habitat structure, the demographic bottleneck hypothesis, which proposes that shelter limitation can control population size structure and recruitment density by acting strongly on only one size class. To test this hypothesis, I first experimentally manipulated the size-specific availability of shelter for stone crabs in St. Joseph Bay, Florida, and I found evidence for a bottleneck that affects the growth and fecundity of large stone crabs. / These results provide support for the demographic bottleneck hypothesis, but they do not address its generality. It is a common problem in ecology that we rely on singular tests of hypotheses and the scientific generalization of these results. To address this problem, I suggest that we repeat experiments and use random factors more often in experimental designs. The use of random factors can lead to an unbiased estimate of the generality of patterns and to an understanding of the mechanisms that underlie these patterns. / To address these concerns, I repeat the shelter supplementation experiments in St. Joseph Bay and in three additional haphazardly-selected bays in the northeast Gulf of Mexico in a mixed-model experimental design. In addition to the shelter manipulations, which test the bottleneck hypothesis at the individual level, I use observational and experimental techniques to examine five biotic factors (habitat structure, food, predation, settlement, and competition) that may contribute to population-level differences among bays. / I find differences among bays in the natural population-level parameters of stone crab size structure and density and in crab responses to shelter supplementation. The demographic bottleneck hypothesis best accounts for these differences. I show that there are demographic consequences of shelter limitation on stone crab growth and fecundity at the individual level, and that these effects appear to explain population-level differences among bays. However, the demographic bottleneck hypothesis does not explain all the differences in crab populations. The bottleneck effects are mediated by differences in food, competition, and settlement among bays. / Source: Dissertation Abstracts International, Volume: 56-11, Section: B, page: 5894. / Major Professor: Daniel S. Simberloff. / Thesis (Ph.D.)--The Florida State University, 1995.

Etheostoma flabellare has a long history of taxonomic confusion due to complex patterns of morphological variation. Four or five subspecies are currently recognized. Alternative hypotheses suggest species-level descriptions are warranted. No studies have tested the morphology-based taxonomy and phylogenetic relationships have not been proposed. Relationships within the E. flabellare species group of Catonotus are also problematic Genetic markers are used to generate phylogenies to test alternate taxonomic hypotheses for E. flabellare by examining patterns of lineage diversification and the monophyly of subspecies. Phylogenies are also used to examine relationships within the species group and test hypotheses associated with Central Highlands Vicariance Biogeography. Mitochondrial haplotypes are used to examine population genetic structure and test the predicted limited dispersal ability of E. flabellare. Associations between phylogeny and geography of haplotypes are examined with nested clade analysis (NCA) to infer historic and ongoing population-level processes that have been important in the evolutionary history of the species and in shaping genetic structure. NCA fragmentation events are re-examined in a phylogenetic context and to identify evolutionary lineages that warrant species-level recognition Phylogenies recover each subspecies as paraphyletic, providing no support for the current taxonomy. High genetic divergence among geographically-concordant monophyletic clades suggests that species-level designations more accurately describe diversity and highlight the need for taxonomic revision. Relationships recovered for E. flabellare species group members suggest species group designations within Catonotus require revision. Phylogeographic patterns illustrate that current clade distributions and diversity in E. flabellare require vicariant and dispersal explanations. Population-level genetic structure shows that E. flabellare is subdivided at broad and fine spatial scales, supporting limited dispersal ability as predicted by intrinsic and extrinsic features of the species. NCA revealed significant non-random associations between the phylogeny and geographic distribution of haplotypes, rejecting the hypothesis of panmixia in E. flabellare populations. NCA recovered several population processes, including historic fragmentation, restricted gene flow, and range expansions, highlighting the complexity of events associated with the history of the species and its genetic diversity. Most inferred fragmentation events corresponded to populations that also formed exclusive phylogenetic clades, further supporting unrecognized species-level diversity in E. flabellare / acase@tulane.edu

This study examined a number of factors that could potentially influence male reproductive activities in the spiny orbweaving spider, Micrathena gracilis. In this species a complete mating between a pair requires two copulations, one for each female reproductive tract. Spiders are excellent subjects for research into reproductive behavior yet the effects of factors such as male and female history on copulatory frequency, duration, sperm release, and sperm induction have been virtually unexplored. Collectively, findings reported here indicate that both female and male histories influence male reproductive activities and that some components of mating behavior are more flexible than others The importance of female mating history to male reproductive activities was examined in Experiment 1. Results showed that sperm release was largely controlled by the status of the female's tract; virgin tracts elicited release while most mated tracts did not. Sperm were released in an all-or-none fashion. Male collection history was also examined by comparing free-ranging males with those that molted to adulthood in captivity. Collection history influenced the frequency of copulation but not duration or sperm release The observation that some males release sperm to some non-virgin females was examined in more detail in Experiment 2. Results indicate that such release is related to a female signal that does not reflect the actual mated status of the tract, and not male error in assessment of that tract The importance of male mating history on male copulatory behavior was examined in Experiment 3. Male experience influences copulatory frequency and duration but not sperm release. A male's motivation to mate with a female was influenced by the status of the previous female with which the male had mated. Timing of female presentations and numbers of females presented were manipulated in order to simulate variation in female density. Such manipulation influenced a male's motivation to mate and copulatory frequency Despite the uniqueness of sperm induction, it is, however, one of the more understudied areas of arachnid behavior and was the focus of Experiment 4. Results indicate that sperm induction is influenced by the mating history of the female and of the male / acase@tulane.edu

The vast majority of aquatically feeding tetrapods rely on suction feeding or filtration mechanisms, which is generally achieved via a robust hyoid apparatus that, when depressed, acts to increase the volume of the buccal cavity, thereby increasing the pressure differential between the buccal cavity and the surrounding water. In snakes, however, the hyoid apparatus is largely reduced as a consequence of its specialization for chemoreception, and hence cannot be used to expand the oral cavity and generate suction. Consequently, snakes must strike at aquatic prey in a manner similar to that used in terrestrial environments. As snakes are unable to generate suction, aquatic strikes will likely involve high drag forces and will be subjected to substantial bow-wave generation. Previous authors have thus predicted that aquatically feeding snakes should have relatively small heads that taper towards the back in order to minimize these hydrodynamic constraints. Yet, snakes are gape-limited predators (predators that do not mechanically reduce their prey before ingestion), and thus a relatively small head will influence the maximum prey size that can be ingested. These functional demands on the snake feeding apparatus predict that (1) aquatically feeding snakes will exhibit slowed head growth with increasing body size, and consume relatively smaller prey; and (2) aquatic strikes will be markedly slower than terrestrial strikes A second related issue is the fact that little data exists on which prey dimensions are the most functionally difficult to ingest for gape-limited predators such as snakes. Although numerous studies have used predator-prey mass ratios to shed light on issues such as optimal foraging theory, community level trophic relationships, ontogenetic dietary shifts, mass ratios are likely an overly simplistic view of the dynamic relationship between predators and their prey. Instead, data are needed that explore which prey dimensions are the most functionally difficult to ingest and most strongly influence feeding performance. Such data could be used to more clearly formulate optimal foraging models and could shed light on community level trophic relationships A third related issue is the influence of foraging mode (sit and wait versus active foragers) on the sensory modalities used for prey detection. (Abstract shortened by UMI.) / acase@tulane.edu

acase@tulane.edu

The impact of changes in environmental variables on (a) female behavior during pregnancy, (b) breeding success, and (c) infant development was examined in captive squirrel monkeys (Saimiri boliviensis). Crowding and hand-capture and restraint for ultrasound were used to create environmental stresses during pregnancy, birth, and infant rearing. The results indicate that ultrasound did not by itself have a significant effect on any part of the breeding process. However, when ultrasound was combined with crowding, the detrimental effects caused by crowding alone on infant birth weights and growth rates were exacerbated. Rates of affiliation (p < 0.01) and agonism (p < 0.0001) and duration of affiliation (p < 0.001) all significantly decreased with decreasing cage space. Infant birth weights (p < 0.02) were also significantly lower in the most disturbed infants. Motor maturity scores (p < 0.02) were significantly lower in infants born to crowded mothers and strong trends showed reduced scores for several other categories of muscle development in these infants. Evidence for a possible conflict avoidance mechanism for coping with crowding was indicated. The results demonstrate a strong effect of cage size on female behavior during pregnancy and infant development that deserves further investigation I continued investigating the effects of crowding by altering timing of the stressor during different phases of pregnancy. Frequency of affiliation (p < 0.01) and genital displays (p < 0.05) increased significantly during crowding. Genital display frequency increased significantly during post-stress recovery (p < 0.03). Grooming bouts were frequent during crowding, which is rare in this species under normal conditions. Sociograms indicate strong huddle pattern differences between early-crowded and latecrowded females. Early-crowded females demonstrated greater fluidity in huddle-partner preference during stress and post-stress recovery than late-crowded females. The results indicate a possible active-coping mechanism as a response to crowding. Early-crowded infants appeared to be slightly developmentally delayed As a whole, indications are present that the sociosexual makeup of the social group affects the behavioral reaction to environmental stressors in this species. New group formation and new mate introduction were successfully used as tools for manipulation of reproductive cycles in this species. These results have important management implications for improving the health of the breeding stock, increasing the successful birth rate, and insuring optimal development of future breeders in captive-breeding populations / acase@tulane.edu

A pilot study of body shape variation in three species of darters (Etheostoma caeruleum, E. nigrum, and E. stigmaeum) showed significant variation among species and among populations within species, and suggests that conclusions regarding darter body shapes drawn from interspecific comparisons are robust to significant intraspecific variation. The remaining studies addressed interspecific variation in body shapes and reproductive life-history traits as they relate to body size (S), phylogeny, and each other, based on data collected from 1,089 reproductive female darters representing 32 taxa (species and subspecies) Within taxa, clutch size (CS) was found to be significantly associated with S for 28 of the 32 taxa, as was ovum mass (OM) for 10 and clutch mass (CM) for 13. All three were significantly correlated with S for all individuals as a group, and were therefore size-adjusted in subseqent analyses. Using four recent phylogenies, I tested for phylogenetic effects on S, size-adjusted life-history traits, and the slopes of the regressions of CS on S. Body size showed no evidence of phylogenetic effects, but conflicting results were found for the remaining variables, highlighting these tests' sensitivity to differences among phylogenies In contrast, geometric morphometric analysis showed consistent evidence of phylogenetic effects on body shapes. Transformation grids revealed qualitative similarities within most higher taxa, and this observation was confirmed with ordination and cluster analyses. Mantel tests showed significant positive association between body shapes and each of the four phylogenies---a surprising result, given the large differences among them. To examine this result further, I reanalyzed the data including only a single representative species per subgenus, which rendered the correlations insignificant for three of the four phylogenies Associations between body shape and life-histories were tested with phylogenetic generalized least squares multiple regression. The results indicated that body shape explains relatively little (13--24%) of the observed variation in size-adjusted CS or OM, but explains much (39--58%) of the variation in size-adjusted CM. Subsequent examination revealed that the best predictors of life-history variation were those measures associated with body depth / acase@tulane.edu

The fields of sexual selection and physiological ecology have traditionally remained separate throughout much of the history of evolutionary biology, despite the surge of interest in integrative biology over the last decade. However, a growing literature is showing that whole-organism performance abilities (including locomotor ability) influences the outcomes of competitive male-male interactions in several territorial lizard species. These findings raise the possibility that fighting ability, a previously undefined trait also referred to as resource-holding potential, may be rooted in measureable, functional concepts such as speed or endurance. Furthermore, if performance capacities do comprise an appreciable component of fighting ability, than those capacities might have become linked over time to the evolution and expression of male secondary sexual characters used during fights (i.e. armaments) I show here that whole-organism performance capacities (in particular, bite force) play a major role in resolving agonistic encounters between males in territorial Anolis lizard species, but may have little or no effect on determining male fight outcomes in non-territorial anole species. I also show that whole-organism performance traits used during male combat are linked to secondary sexual trait expression in male Euoniticellus intermedius dung beetles in an independent test of the performance signalling hypothesis. By contrast, although the size of the Anolis male secondary sexual character (the throat-fan, or dewlap) is linked to bite force in some territorial anoles, dewlap size does not influence fight outcomes in this species. However, dewlap size does influence fight outcomes in non-territorial anoles that do not rely on performance capacities to win fights. This puzzling role of dewlap size in resolving male-male conflicts is a cautionary note for future behavioural studies. I also show that male performance abilities appear to have no effect on male mating preferences in the green anole Anolis carolinensis, and find no evidence for performance as part of a suite of male traits preferred by choosy females Finally, I review previous studies integrating elements of sexual selection, physiology, and performance, and point out several important areas where further integration of physiological ecology and sexual selection techniques might yield important insights into the evolution of animal mating systems / acase@tulane.edu