Scleractinian coral populations are declining worldwide in response to numerous stressors operating on both global and regional scales. Rising sea surface temperatures associated with global climate change and the increasing frequency of coral-macroalgae competitive interactions are two of the gravest ecological drivers facing coral reef ecosystems. However, little is known about how these stressors interact to impact corals, their health, and potential modes of population recovery. These threats also highlight the need to develop reliable techniques that detect stress in multiple life-history stages of hermatypic corals prior to the degradation of coral reef habitats. To address these concerns we evaluated the effects of elevated sea surface temperatures (+3.5°C), Dictyota menstrualis competition, and their combined impacts on three life-history stages of the reef-building coral Porites astreoides. Elevated temperature induced sub-lethal stress yet had varied responses that were contingent on the life-history stage being examined. Hyperthermal stress did not consistently effect the transcriptional expression of heat shock proteins (Hsp) 16 or 60, but was readily detected utilizing biomarkers of the oxidative stress pathway. The presence of D. menstrualis significantly reduced coral survival and recruitment beyond simple space occupation in every coral life-history stage examined.While macroalgal exposure and elevated temperature had distinct effects on coral survival and physiological condition, the combination of both stressors induced a synergistic impact on biomarkers of oxidative stress in coral larvae. The results highlight the potential of biomarkers of oxidative stress for detecting hyperthermal stress in scleractinian corals. They also support the accepted notion that benthic macroalgae compete with reef-building corals via direct contact for space on coral reefs and that elevated temperatures can reduce the health of the coral holobiont. In addition, the results indicate that larvae from P. astreoides are more susceptible to the impacts of hyperthermal stress compared to established corals and that multiple perturbations can interact to exacerbate coral health.

The origins of population dynamics depend on interplay between abiotic and biotic factors; the relative importance of each changing across space and time. Predation is a central feature of ecological communities that removes individuals (consumption) and alters prey traits (non-consumptive). Resource quality mitigates non-consumptive predator effects by stimulating growth and reproduction. Disturbance resets predator-prey interactions by removing both. I integrate experiments, time-series analysis, and performance trials to examine the relative importance of these on the population dynamics of a snail species by studying a variety of their traits. A review of ninety-three published articles revealed that snail abundance was much less in the Everglades and similar ecosystems compared to all other freshwater ecosystems considered. Separating consumptive from non-consumptive (cues) predator effects at different phosphorous levels with an experiment determined that phosphorous stimulated, but predator cues inhibited snail growth (34% vs. 23%), activity (38% vs. 53%), and reproductive effort (99% vs. 90%) compared to controls. Cues induced taller shells and smaller openings and moved to refugia where they reduced periphyton by 8%. Consumptive predator effects were minor in comparison. In a reciprocal transplant cage experiment along a predator cue and phosphorous gradient created by a canal, snails grew 10% faster and produced 37% more eggs far from the canal (fewer cues) when fed phosphorous-enriched periphyton from near the canal. Time-series analysis at four sites and predator performance trials reveal that phosphorous-enriched regions support larger snail populations, seasonal drying removes snails at all sites, crayfish negatively affect populations in enriched regions, and molluscivorous fish consume snails in the wet season. Combining these studies reveals interplay between resources, predators, and seasonality that limit snail populations in the Everglades and lead to their low abundance compared to other freshwater ecosystems. Resource quality is emerging as the critical factor because improving resources profoundly improved growth and reproduction; seasonal drying and predation become important at times and places. This work contributes to the general understanding in ecology of the relative importance of different factors that structure populations and provides evidence that bolsters monitoring efforts to assess the Comprehensive Everglades Restoration Plan that show phosphorous enrichment is a major driver of ecosystem change.

In order to ascertain the degree of compatibility in developmental restructuring and behavioral plasticity between two fish species frequently made subject of laboratory research (Metriaclima zebra & Danio rerio), alternative trophic niche exposure experiments utilizing novel three-prong feeding treatments were conducted to obtain morphometric data, which demonstrated both species do bear some degree of plasticity. The results are somewhat complicated by differences in locality of detectable restructuring, which may be due to disparity in the form-function relationship for each species’ lineage. Each is notable in the manner of respective species’ jaw protrusion, as it is driven by anterior kinethmoid rotation in D. rerio. as opposed to force imparted upon the rostral cartilage of the premaxilla’s articular process in M zebra. Each is markedly distinct in the pharyngeal jaw as well, as zebrafish (also toothless at the oral jaw) bear teeth only on the lower set at the posterior of the mouth, while cichlids bear teeth on all jaws and additionally possess a unique, fused lower pharyngeal jaw. However, accounting for this difference in experimental models does allow for direct comparison, both at the morphological/behavioral and potentially the genetic level, though additional research is necessary. The evidence provided here also provides encouragement that more nuanced approaches to laboratory trophic niche exposure experiments could elucidate further evidence on the nature of phenotypic plasticity.

Amphibian populations are declining globally due to a litany of factors including pollution, disease, climate change, and most importantly, habitat destruction. As most amphibian life histories involve their populations being recruitment limited, focusing on the mechanism behind breeding habitat selection will reveal useful cues that managers may use to increase abundance and breeding success. Though there are many theoretical models that describe the distribution of animals in response to a resource, the ideal free distribution (IFD) theory has not yet been applied to amphibian settling decisions. Through this application of the IFD, I have found that a population of wood frogs (Lithobates sylvaticus) in Patuxent National Wildlife Refuge select vernal pools that are large, deep, and hold water into the summer months to breed from 2010-2015. This information will provide managers with the ability to predict sites where wood frogs will breed in the future, as well as describe the cues that wood frogs are cueing in on so we can protect, alter, or create ideal breeding habitat.

As the earth’s climate changes due to anthropogenic emissions, it has increasingly become an imperative within the ecological community to understand existing species adaptations to climate change. Much focus has been paid to how a species might react to climate change, but the role of locally adapted traits and responsible environmental mechanisms have received less attention. Quantifying how sublethal (e.g. growth rates) and lethal (e.g. thermal tolerance) trait performance vary between populations can thus improve our understanding of how populations, and the entire species, will react to climate change. Here, I quantified the spatial patterns of performance of several traits in populations of the predatory marine snail Urosalpinx cinerea from across two thermal gradients on the Pacific and Atlantic coasts of North America. In chapter 2, I quantified local adaptation and plasticity of thermal tolerance, warming tolerance, and developmental traits of Urosalpinx. I found that while low latitude populations have evolved higher thermal tolerance than their low latitude counterparts, they also demonstrate negative plasticity in response to higher acclimation temperatures. This is likely a result of low latitude population adaptation to cooler developmental conditions. Further, low latitude populations live in environments much closer to their thermal maxima than high latitude counterparts, resulting in higher climate sensitivity in low latitudes. In chapter 3, I quantified growth and consumption rates of Urosalpinx via a common garden experiment. I found evidence for a novel pattern of trait adaptation, wherein high latitude populations tended to have higher trait performance at higher thermal optima than low latitude counterparts. This can be attributed to the maximizing of growth rate during short growing seasons at high latitudes. Together, these results demonstrate that local adaptation in endemic across two traits in Urosalpinx. I demonstrate that these traits tend to be adapted to aspects of the environment directly related to aspects of Urosalpinx phenology, and not to environmental means as is commonly assumed. These insights suggest that models of organismal performance under climate change must consider not only the potential for local adaptation in populations, but also the aspects of the environment to which these populations are evolved.

Emplectonema gracile (Johnston 1837) is a hoplonemertean of marine intertidal hard-bottom communities and is distributed throughout the Northern Hemisphere. Although possessing a planktonic larval stage in its life history, the range of such cosmopolitan marine invertebrate species is often explained by cryptic speciation and anthropogenic transport. The purpose of this study is to test for possible cryptic species using mtDNA markers (COI and 16S rDNA) and to investigate population structure in E. gracile over a portion of its geographic range using mtDNA markers and ddRADseq nuclear SNP data. The results of both phylogenetic- and tree-based species delimitation revealed that E. gracileis a morphotype containing cryptic species. Three North Atlantic and one Pacific coast population are inferred as one species (E. gracile sensu stricto) and two Pacific coast populations (Akkeshi, Japan and Charleston, Oregon) are inferred as another species (Emplectonemasp 1), strongly confirming an earlier study and extending the range of the latter species to the Pacific coast of Japan. Anthropogenic transport is suggested as the likely mode of transport for E. gracile.Both Fst, PCA and haplotype network analyses suggest a lack of differentiation between E. gracile populations separated by large geographic distances.In contrast corresponding analyses forEmplectonemasp. 1 indicate differentiation between the two populations sampled. Further research will be necessary to reveal if rare anthropogenic transport or natural dispersal (larval transport, rafting) between geographically adjacent yet to be delimitedE. gracile morphotype populations is responsible for its seemingly disjunct distribution.

During the summer of 2008 and 2009, we studied the ecology of the Kittlitz’s Murrelet (Brachyramphus brevirostris), a small diving seabird and candidate for the U.S. Endangered Species List, in Prince William Sound (PWS), Alaska. At-sea survey data suggests that the population significantly increased from 2001 to 2009, however there is limited evidence of reproductive success. Habitat use models showed individuals were observed in shallower waters, closer to glaciers, the shoreline, and further from moraines than the available habitat during the daytime. Finer extent sampling from 2008 suggests temperature-depth profiles also influence Kittlitz’s Murrelet daytime habitat use. The associations between Kittlitz’s Murrelets and water column characteristics are likely an effect of prey availability. Stable isotope work in 2009 suggests birds were generalist foragers prior to the breeding season, becoming more specialized following the breeding season. This specialization may have been a response to strict foraging constraints during the flightless fall molt. Time budgets of radio-tagged individuals suggest birds may have been responding to ephemeral prey concentrations, and working near their maximum energetic limits. Remote monitoring of radio-tagged individuals showed birds left the glacial fjord system during the nighttime, possibly spending these hours near gillnet fishing areas, suggesting a new possible area of concern in evaluating potential threats to Kittlitz’s Murrelet populations.

Death and decomposition are natural processes that are generally well-understood. However, large events of death, such as mass mortality events (MMEs) are increasing in frequency and their impacts on the ecosystem are largely unknown. These events may have both bottom-up effects from increased nutrient input as well as top-down effects from loss of an ecological functional group by the affected population. Different functional MMEs may result in different top-down effects, creating cascading effects. In Chapter 1, I test the hypothesis that scavenger and herbivore simulated MMEs generate novel bottom-up and top-down effects. Results indicate that MMEs have a significant effect on communities, including on soil chemistry, plant tissue, soil microbes, and soil arthropods. Carrion effects on the community were both a result of biomass (MMEs vs. single carcasses) as well as functional group exclusion (herbivores, scavengers). Further, MMEs may also generate long-lasting community effects due to the size and nature of the disturbance. In Chapter 3, I evaluated the potential long-term of effects of MMEs by sampling an experimental MME that was conducted four years earlier. I found that MMEs generated long-term asymmetrical effects on ecosystems, with some noticeable changes in increased soil nutrients as well as an unexpected effect of biomass on aboveground arthropod communities, with very little effect on belowground soil arthropods. However, studies of long-term decomposition from mass carcasses may expand beyond studying MMEs. Composting of carrion is a continuous disturbance event, with numerous carcasses being deposited in the same location over a longer period of time. In Chapter 2, I analyzed potential effects on the surrounding community at a unique instance of concentrated carcass disposal (5 years old). Significant differences were revealed between samples taken near the compost pit (0 m, 5 m) compared to further distances (10 m, 25 m, 50 m) with calcium being increased away from the pit, different soil microbial communities at the pit than farther distances and increased aboveground arthropod abundance at the pit. These experiments provide us with a greater, holistic understanding of previously understudied events of mass death on community structure and ecosystem function.

North American black bears and brown bears can be difficult to distinguish in the fossil record due to similar dental and skeletal morphologies. Challenges identifying ursid material from Oregon Caves National Monument (ORCA) called for an accurate tool to distinguish the species. This study utilized a large database of lower tooth lengths and ratios in an attempt to differentiate black and brown bears in North America. Further, this project examined how these linear measurements differ geographically. Analysis of variance (ANOVA) found significant differences between black and brown bears from across North America for every variable studied. Stepwise discriminant analyses (DA) found lengths separated species better than ratios. When sexes were analyzed, ANOVA only found significant differences for lengths while DA found lengths and ratios could not accurately distinguish between sexes. Fossil specimens from North America, including ORCA specimens, demonstrated the utility of this study, supporting several identifications and questioning others.

An ongoing debate concerning Neandertal ecology is whether or not they utilized long range weaponry. The anteroposteriorly expanded cross-section of Neandertal humeri have led some to argue they thrusted their weapons, while the rounder cross-section of Late Upper Paleolithic modern human humeri suggests they threw their weapons. We test the hypothesis that Neandertal humeri were built to resist strains engendered by thrusting rather than throwing using finite element models of one Neandertal, one Early Upper Paleolithic (EUP) human and three recent human humeri, representing a range of cross-sectional shapes and sizes. Electromyography and kinematic data and articulated skeletons were used to determine muscle force magnitudes and directions during three positions of spear throwing and three positions of spear thrusting. Maximum von Mises strains were determined at the 35% and 50% cross-sections of all models. During throwing and thrusting, von Mises strains produced by the Neandertal humerus fell roughly within or below those produced by the modern human humeri. The EUP humerus performed similarly to the Neandertal, but slightly poorer during spear thrusting. This implies the Neandertal and EUP human humeri were just as well adapted at resisting strains during throwing as recent humans and just as well or worse adapted at resisting strains during thrusting as recent humans. We also did not find any correlation between strains and biomechanical metrics used to measure humeral adaptation in throwing and thrusting (retroversion angle, Imax/Imin, J). These results failed to support our hypothesis and suggest they were capable of using long distance weaponry.