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Waterbirds have died of lead poisoning from ingesting lead sinkers in the United States and Europe. Other tackle and litter has also caused injury and mortality to waterbirds. Despite risks posed to waterbirds, no studies of the abundance of tackle or litter in freshwater systems of the United States have been completed. We tested the effectiveness of a metal detector to search for lost and discarded tackle, and developed a technique to correct densities of sinkers. We then quantified tackle and litter abundance at various sites around the United States. Tackle and litter densities varied among sites, but were generally highest in heavily fished areas. Based on the distribution of tackle in light of known mortalities caused by ingestion of sinkers, restrictive management of lead poisoning from sinkers may not be justified. However, lead is a toxic substance and its continued use when nontoxic alternative are available is not logical.

Gila chub (Gila intermedia) were at lower densities in areas of Sabino Creek with green sunfish (Lepomis cyanellus) than areas without sunfish. No young-of-year (YOY) chub were observed in pools where densities of sunfish were reduced by about 90% or in control pools, but YOY chub were abundant in upstream areas without sunfish. The microhabitat selected by YOY chub was nearly identical to that selected by sunfish (7.5 cm, TL). In predation experiments, sunfish (7.5 cm, TL) consumed YOY chub (2.5 cm, TL). The absence of YOY chub in areas with sunfish may, in part, be due to predation by small sunfish. In winter, chub use of microhabitat did not differ in areas with and without sunfish. In summer, chub used faster currents, areas farther from cover and shallower depths in areas with than without sunfish. In summer, niche shifts by chub may be a response to avoid negative interactions with sunfish.

Large carnivores are in global decline, chiefly resultant of anthropogenic persecution, habitat reduction and disturbance. Fosas represent Madagascar's largest carnivore, occupying much of the island's forest. This thesis examines the threats of bushmeat hunting, retaliatory killing, habitat alteration and exotic species using sociological and remote-sensing methodologies. Habitat degradation was not associated with reduced fosa occupancy, indicating some resilience within large, contiguous forests. However, competition with exotic species (cats, dogs) was associated with reduced fosa occupancy and potential temporal shifts towards greater nocturnality. Poor households were more likely to consume protected species. Conversely, wealthier households consumed more fish and eel. This pattern is reflected in Malagasy reported taste preference to consume domesticated animals and certain legally hunted wild species. Protected areas were not associated with reduced protected species consumption. Fosas' predation was a major cause of rural poultry mortality. Predation was more likely to occur in deciduous forests, in the dry season, during the evening. Fosa predation, and lower education was associated with negative Malagasy attitudes. Wealthy households, and those that had experienced fosa predation were most likely to retaliatory kill a fosa. Strategies to safeguard fosas' long-term persistence should seek to improve domestic husbandry, build robust coops with the use of watchdogs, promote education, and reduce exotic species abundance.

The northern Swallow-tailed Kite, Elanoides forficatus forficatus, a Neotropical migrant raptor of conservation concern, has failed to recover its former abundance and breeding range following widespread deforestation of breeding habitat and human persecution beginning in the late 19 th Century. The Louisiana-Mississippi subpopulation studied here appears to be limited by intraguild predation involving other species of raptors, especially Great Horned Owls (Bubo virginianus). Predation was documented using a multiple-methods approach that minimized sources of bias. Intraguild predation impacted the subpopulation in multiple ways: Raptors, particularly Great Horned Owls, killed kites of all ages, but especially adult females attending nests, possibly causing breeding-aged female limitation. During monitoring of 290 nests, recently fledged young, and radio-tagged birds (90 fledglings, 13 adults), intraguild predation was the leading cause of mortality, accounting for 50.5-56.8%. Considering mortality attributable to predators on or near nests, the Great Horned Owl was responsible for 50.5-98.1%. Raptor predation was also the leading cause (44.8%) of nest failure (N = 87 failed nests), the remainder attributable to weather and other factors. Intraguild predation was the key-factors (greatest impact on mortality of nest contents), explaining most variation in annual productivity, although weather and unknown causes were nearly as important. Productivity also declined at a rate of 0.057 young per year (1995-2005, 305 nests), and the annual frequency of nest predation contributed substantially to this decline (r = -0.728). Considering radio-tagged fledglings, 12.2% were depredated by raptors (at least 54.5% by owls) prior to first migration. Predation of adult kites attending nests during the 60-day exposure period for this species contributed between 7.87-9.62% to annual adult mortality. Raptor predation was the probable explanation for 81.8% of 22 instances of nesting neighborhood disappearance. The present study identifies the Great Horned Owl as a keystone predator of kites and many other birds Intraguild predation alone is not sufficient to explain the slowness of the kite's recovery. Additional factors implicated include (1) delayed age of first reproduction, perhaps as late as five years of age; (2) social dominance by adults slowing recruitment by pre-breeders failing to obtain a mate or territory; and (3) conspecific attraction potentially inhibiting re-colonization of formerly inhabited geographic areas / acase@tulane.edu

This study was undertaken to elucidate the synthesis site or sites of the major yolk protein, vitellin (Vt), in the red swamp crayfish, Procambarus clarkii. Vitellin was purified from late vitellogenic ovaries (containing oocytes $\ge$456 $\mu$m in diameter). The protein was purified by ultra centrifugation, gel filtration, and finally native polyacrylamide gel electrophoresis. Once the purified form of the protein was attained it was used to create polyclonal and monoclonal antibodies by inoculating rabbits and mice, respectively. The specificity and sensitivity of the antisera were each determined by titering using sandwich enzyme-linked immunosorbent assay (ELISA). The antisera were used to design a competitive quantitative ELISA for Vt and its precursor, vitellogenin (Vg), which is immunologically identical in many crustaceans. The concentrations of Vt in ovaries and Vg in hemolymph were determined in relation to the stage of reproductive maturity as determined by oocyte diameters. The total aqueous protein concentration in developing ovaries ranged from 1% to 5% and consisted of 23% to 55% Vt. The Vt concentrations from ovaries of sixteen mid-vitellogenic females averaged 38% of the total aqueous protein. The competitive ELISA was sensitive to standard Vt concentrations as low as 62 ng/ml and was capable of distinguishing concentrations as high as 8 $\mu$g/ml. Hemolymph Vg concentrations, determined from diluted hemolymph samples (1:20), ranged from 10 $\mu$g/ml in early vitellogenic females to 2880 $\mu$g/ml in late and post-vitellogenic females. There was a correlation between ovary maturity and specific hemolymph Vg concentrations after the onset of vitellogenesis. Hemolymph Vg concentrations are attributed to leakage and reabsorption of Vg and Vt, respectively, through the thin ovarian wall. Polyclonal antibody preabsorbed to male hemolymph was used for fluorescent (FITC) and enzymatic (DAB) immunohistochemistry for Vt or Vg localization in ovary and hepatopancreas sections from females of all reproductive stages and hepatopancreata of males (controls). Immunohistochemical analysis indicated no presence of Vg in males or female hepatopancreata at any reproductive stage. Ovaries showed Vg presence in ovarian stroma associated with follicle cells or a possible subset of which we call vitellocytes. Presence of Vt in oocytes corresponded closely to timing of folliculogenesis and concentrations of Vt can be related to relative numbers of secondary follicle cells present. Finally, our results indicated that the ovary may be the sole site of Vg synthesis and that the follicle cells are responsible for the production and transport of yolk protein to developing oocytes / acase@tulane.edu

<p>Humans are more carnivorous than other hominoids. It has been hypothesized that, during the evolution of this increased carnivory, hominins transitioned through a scavenging niche made viable by certain carnivoran taxa (especially sabertooths) that may have lacked the morphology necessary to fully utilize all parts of carcasses (e.g., marrow), therefore leaving an open niche in the form of high-quality scavengable remains available for hominins. In this dissertation, I examine the postcanine dentition of modern carnivorans, using quantifications of occlusal radii of curvature and intercuspid notches, and study the correlation of this morphology with carcass-processing behavior. I use these correlations to deduce the carcass-processing capabilities of the Plio-Pleistocene carnivores of South Africa (a guild for which we have a good appreciation of taxonomic diversity, and that existed at an important time during the evolution of our lineage - possibly the time that we transitioned into that guild), and compare these results with those of previous studies that relied on more conventional morphological measures.</p><p>Both radius of curvature and intercuspid notch data do a good job of separating taxa by dietary category, revealing subtle patterns including possible differences in the carcass-processing abilities of fossil and modern members of some extant species. Other strong trends confirm that the "hunting-hyena," Chasmaporthetes, was probably a hypercarnivore, and not a durophage like its modern confamilial taxa. Somewhat surprisingly, results do not support the hypothesis that sabertooth felids were more hypercarnivorous than modern felids. Furthermore, though the sympatric hypercarnivorous taxa were more numerous, so to were the durophageous taxa, with one taxon, Pachycrocuta, probably exceeding the durophageous capabilities of modern durophages.</p><p>As such, this dissertation shows no evidence that members of the paleo-carnivore guild were capable of producing higher quality scavengable carcasses than are modern carnivorans, and thus, based on these analyses of fossil carnivorans, it does not appear that high-quality scavengable remains were more available in the Plio-Pleistocene than there are today. Therefore, though there is clear evidence from other sources that hominins did scavenge at least occasionally, this dissertation does not support the hypothesis that there was an open niche consisting of high-quality scavengable remains.</p> / Dissertation

<p>The pace of life history is highly variable across mammals, and several evolutionary biologists have theorized that the tempo of a species' life history is set by external factors. These factors, such as food availability and predation pressure, determine mortality rates. In turn, mortality rate determines the age at maturity. High mortality rate results in early age at maturity; individuals must grow and reproduce quickly because of the high risk of death. Conversely, a low mortality rate is allows individuals to prolong their growth period and reproduce slowly. This theory assumes that growth rates are constant across species, and thus body size is determined by mortality rates.</p><p>This project posits that the intrinsic characteristics of species set the pace of life history. Among anthropoids, there is a great deal of variation in growth rates and the pace of life history relative to body size. The hypotheses proposed by this project state that the degree of encephalization in a species determines the growth rates, the length of the growth period, and the adult lifespan. Growing a large brain is costly and requires a prolonged period of development. However, a large brain has the benefit of reducing mortality by facilitating cognitive strategies for food procurement and predator avoidance. This cost/benefit balance results in the pattern of life-history variation in which mortality rates are correlated with the length of the growth period. However, the causal arrows are reversed; instead of the mortality rate determining the age at maturity and consequently the size of the species, the relative brain size of the anthropoid determines the mortality rate and the age maturity.</p><p>These hypotheses were tested by determining the body and brain growth trajectories of thirteen anthropoids, and compiling life-history data from long-term studies of these species in the wild. Multi-variate analyses demonstrated that extensive brain growth, whether through prolonged duration or rapid growth rates, results in slow body-growth rates during the juvenile period and delayed age at maturity. In addition, encephalization results in longer adult lifespan. Therefore, this project demonstrated that intrinsic characteristics of anthropoid species determine the pace of their life histories.</p> / Dissertation

<p>A long-held assumption in animal behavior is that females and males differ fundamentally in their mating strategies. Females are thought to be more choosy because female reproduction typically is limited by parental investment. Males, on the other hand, are expected to compete among themselves for access to females or resources, since male reproduction is limited primarily by mating access. This dichotomy is challenged by the increasing realization that males can be choosy and females also compete aggressively. It remains unclear, however, if and how selection acts on aggressive behavior in the context of intrasexual competition among females (reviewed in Chapter 1). In this thesis, I use a population of free-living tree swallows (<i>Tachycineta bicolor<i>) to test predictions about the selective pressures shaping aggressive behavior in females. First, using an experimental manipulation of nest site availability, I demonstrate that more aggressive females have a competitive edge in acquiring nestboxes, a critical limiting resource required for breeding (Chapter 2). This result shows that more aggressive females are more likely to breed and, thus, that females experience direct selection to be aggressive in the context of competition for mating opportunities. Next, I demonstrate a fitness cost of female aggression (Chapter 3): high levels of aggression in females are not associated with the quantity of offspring, but instead, more aggressive females had offspring of lower quality (i.e. reduced mass). Using a cross-fostering approach, I explore the causal link between female aggression and offspring mass, and I find that a trade-off between female aggression and maternal care best accounts for this cost of aggression. Site differences may create variation in how selection shapes female aggression, but the overall finding that more aggressive females have lower quality offspring indicates that this cost may work counter to selection favoring aggressive behavior in the context of competition over nestboxes. Understanding the evolution of female aggressiveness in a biparental system is incomplete without examining how males may alter the selective environment shaping female behavior. In Chapter 4, I explore the potential role of a female's mate in offsetting the costs of aggression. Males appear to mitigate these costs for their female partners, but not by compensating for poor parenting by aggressive females. Instead, females invest more heavily in reproduction, laying more and larger eggs, when mated to a male that is more different from her own phenotype. If this differential investment outweighs the cost of aggressiveness in terms of offspring quality, then male phenotype may play a key role in understanding the selective pressures shaping the evolution of aggressive behavior in females. Altogether, this dissertation explores the costs and benefits of female aggressive behavior. The focus on aggressiveness as a sexually selected trait in females provides a much needed parallel to the wealth of information already known about the selective pressures shaping sexually selected traits in males.</p> / Dissertation