Variation in embryonic developmental periods influences fitness, but causes of interspecific variation are poorly understood. Allometry, for example, does not explain variation in incubation periods among neotropical passerines. Incubation temperature can explain some variation in developmental periods, but substantial variation remains unexplained. Here we examine two previously untested alternatives. Adult metabolic rates differ among species and similar differences among embryos may explain some variation in embryonic development rates; higher metabolism may allow faster cellular proliferation. Alternatively, metabolic rates are temperature dependent, and metabolic rates might respond differentially to temperature among species and compensate for differing incubation temperatures. These alternatives are untested across any taxa. Therefore, we examined them in tropical Venezuela by measuring embryonic metabolism at four temperatures in 15 passerine species with incubation periods ranging from 12 to 27 days. Embryonic metabolic rates responses to temperature were different among species even at constant embryonic age. Furthermore, species with lower average daily incubation temperature are less sensitive to changes in temperature than species with higher average incubation temperatures. Differences in embryonic mass specific metabolic rate among species explained a significant amount of variation in incubation periods after correcting for incubation temperature. Thus, differences in the rate of living as manifested through metabolism can influence developmental trajectories and deserve greater attention.

In times of heightened environmental consciousness, conservation education programming has proven useful for providing information and promoting natural resource conservation and stewardship. In a study of the 2005 Texas 4-H Wildlife Habitat Evaluation Program (WHEP), a contest teaching youth about the fundamentals of wildlife science and management, I sought to determine if WHEP was successfully reaching its primary goal: promoting conservation by increasing knowledge and skills of youth in the wildlife field. Through a series of facilitator-led interviews with WHEP participants (n = 35) and a combination of internet and on-site surveys (consisting of 35 current participants, 22 control youth, 19 past participants, 25 parents, and 7 coaches obtained from program registration lists), I explored the influence of program participation on wildlife management knowledge, social and leadership skills, attitudes, and understanding of stewardship. I found that WHEP had a significant impact on knowledge of wildlife management techniques and ecological concepts. The program had little influence on attitudes because most youth had positive perceptions of natural resources management prior to program involvement. I also found that past participants of WHEP claimed a significant increase in skills after program participation, but current participants could not determine their own progress. This suggested a longer period of time was needed to gauge self improvement. Parents and coaches claimed the program had a large impact on youth through instilling knowledge and values, but also improving their social, cognitive, and leadership competencies. Adults also discussed issues with participation, including a lack of program expansion and support. From these results, I determined that WHEP was achieving its program goals, but needs to address the issue of expansion because of its low level of operation compared to other 4-H programs in Texas. Suggestions for program growth include targeting youth groups and counties, cross promoting with other conservation programs, and continuing recruitment in currently participating counties.

Skewed sex ratios can have negative implications for population growth or persistence if not congruous for a species system. A skewed tertiary sex ratio (2.3 males per female) has been detected in the breeding population of a grassland shorebird experiencing population declines, the mountain plover (Charadrius montanus). To evaluate the ontogeny of the observed male skew this study examined the early life stages, from laying to fledging, of mountain plover young during their breeding season from 2010 2012 in eastern Colorado. The life stages between laying and fledging that allows for differentiation between production and survival of males and females. Early stages encompass the primary (eggs produced) ratio which allows for evaluation of applied sex allocation theory, the secondary sex ratio (successfully hatched chicks) which determines if a sex specific mortality is occurring pre-hatching, and the chick stage which determines if a sex specific mortality is occurring post-hatching. Mountain plovers are a sexually monomorphic species at all stages therefore DNA samples were used to determine the sex of individuals. The primary sex ratio was 1.01 (± 0.01) males per females. The secondary sex ratio consisted of 1.1 (± 0.02) males per female. Neither the primary nor secondary sex ratio was able to account for the magnitude of the skew observed later in this species adult population. Radio telemetry was used to evaluate the next stage of life, survival of male and female chicks from hatching until fledging. Using a multi-state mark recapture analysis, the top model for predicting chick survival rates estimates differed between males (0.55 ± 0.13) and females (0.47 ± 0.15). The estimated survival difference between the sexes during the chick stage can drive a population with equal survival rates at all other life stages to a ~2.1 :1 adult sex ratio. Results from this study suggest survival difference between males and females at the chick stage is possibly contributing to a male skewed population.

Small populations are at increased risk of extinction due to their vulnerability to stochastic events. The population of fisher (<italic>Pekania pennanti</italic>, formerly <italic>Martes pennanti</italic>) in the southern Sierra Nevada Mountains of California is small and completely genetically isolated. My dissertation research investigates the timing and cause of this population's isolation, the degree of genetic subdivision within the population, the landscape features shaping gene flow, and the detection of population declines. I detected a 90% decline in effective population size and dated the time of decline to over a thousand years ago. Analyzing historical and contemporary genetic samples, I also found a recent bottleneck signal in the northern portion of the southern Sierra Nevada, indicating the southernmost tip of these mountains may have acted as a refugium for fisher in the late 19th century. I conclude that this population became isolated pre-European settlement, and that portions of the southern Sierra Nevada subsequently experienced another more recent bottleneck post-European settlement. I found that the southern Sierra Nevada fisher population is not highly genetically subdivided as previously thought. This population follows a pattern of isolation by distance with additional structuring that corresponds to geographic features and management boundaries. It can be characterized as having areas that are resistant to gene flow but without major barriers. I show that both sex-biased dispersal and spatial landscape heterogeneity can affect the determination of what landscape features structure gene flow, and that the landscape features influencing gene flow are different for each sex and within different geographic regions. Using a spatially-based simulation approach, I investigated the power of the Sierra Nevada fisher monitoring program to detect population trend, and illustrate the relationship between occupancy and abundance in this population. I show that a simulated 43% decline in abundance over an 8-year period only resulted in a 23% decline in occupancy. I also found that increasing the effective sampling area, implementing biennial instead of annual sampling, and increasing the type I error rate all increase statistical power to detect trend. Overall this research provides a better understanding of the historical and contemporary connectivity of this population and our ability to monitor population trends over time that will contribute to the conservation of fisher populations in the future.

Transient dynamics describe short-term responses to unstable conditions in population models. Although the theoretical potential of these short-term effects to change interpretation of model behavior has been demonstrated, it is unclear whether transient analyses will be relevant or useful in management applications. This dissertation explores the role of transient dynamics in plant populations based on long-term demographic data. Based on a survey of modeling results for plant populations in the literature, I found that theoretical indices of transient behavior greatly overemphasized the role of transient responses for the populations for which data were available. Transient indices were indicative of the variation in distance from asymptotic conditions that the models experienced; however, empirical data on long-term environmental variability was substantially closer to asymptotic conditions than theoretical measures. However, transient responses do play an important role in the variability that populations experience. Across nine perennial plant species, transient responses contributed more on average to variability in annual population growth rates than variation in vital rates alone. I also found evidence that transient responses may at times have a buffering effect on the variation that populations experience, by pushing the population in the opposite direction as demographic variation. These results demonstrate the importance of viewing transient dynamics and demographic variation as interrelated processes, with implications for both understanding population dynamics and in management applications. Finally, I explored the role of transient dynamics to assess the non-target impacts of herbicide use on population dynamics of Balsamorhiza sagittata, a native perennial forb in Montana grasslands. Using long-term monitoring data, I found that stage-specific effects of herbicide on Balsamroot demography, combined with episodic recruitment, lead to highly variable population demographic structures during the 10 year study period. My analyses suggest that timing herbicide use based on current population stage structures and mitigating changes to stage structure after spraying could help to minimize long-term impacts of herbicide use on long-lived perennial forbs like Balsamroot. More generally, my analysis demonstrated how information on current population status and specific timescales can be used to better inform management.

In times of heightened environmental consciousness, conservation education programming has proven useful for providing information and promoting natural resource conservation and stewardship. In a study of the 2005 Texas 4-H Wildlife Habitat Evaluation Program (WHEP), a contest teaching youth about the fundamentals of wildlife science and management, I sought to determine if WHEP was successfully reaching its primary goal: promoting conservation by increasing knowledge and skills of youth in the wildlife field. Through a series of facilitator-led interviews with WHEP participants (n = 35) and a combination of internet and on-site surveys (consisting of 35 current participants, 22 control youth, 19 past participants, 25 parents, and 7 coaches obtained from program registration lists), I explored the influence of program participation on wildlife management knowledge, social and leadership skills, attitudes, and understanding of stewardship. I found that WHEP had a significant impact on knowledge of wildlife management techniques and ecological concepts. The program had little influence on attitudes because most youth had positive perceptions of natural resources management prior to program involvement. I also found that past participants of WHEP claimed a significant increase in skills after program participation, but current participants could not determine their own progress. This suggested a longer period of time was needed to gauge self improvement. Parents and coaches claimed the program had a large impact on youth through instilling knowledge and values, but also improving their social, cognitive, and leadership competencies. Adults also discussed issues with participation, including a lack of program expansion and support. From these results, I determined that WHEP was achieving its program goals, but needs to address the issue of expansion because of its low level of operation compared to other 4-H programs in Texas. Suggestions for program growth include targeting youth groups and counties, cross promoting with other conservation programs, and continuing recruitment in currently participating counties.

Thesis (Ph. D.)--Göteborg University, 2003. / Title from home page (viewed June 21, 2004). Added t.p. with thesis statement inserted. Includes bibliographical references. Also available in print.

Summary Throughout the world, terrestrial mammals are hunted for sport, subsistence and population control, providing a significant source of meat and income to communities (Milner et al. 2007). The game ranching industry in South Africa relies heavily on trophy hunting as a primary source of income (du Toit & van Rooyan 2002), and hence may be subject to manipulation that could increase revenue. The industry is growing rapidly, and steps need to be taken to ensure that this industry is sustainable, and is firmly grounded in science with effective government policy. In a recent article in South African Journal of Wildlife Research, von Brandis & Reilly (2008, hereafter vB&R) claim that significant spatial variation exist in the trophy quality (a function of horn size) of ungulates in South Africa and advocate the importance of a national trophy quality monitoring programme in order to control potential manipulation of trophy populations. vB&R raise concerns over the extent of artificial selection being applied in the wildlife industry (see also von Brandis & Reilly 2007). Although these are important concerns within the game industry that require attention, there are philosophical and methodological limitations of this study that question its conclusions. Here we critically assess the analytical approach and the conclusions of that study.

Invasion is associated with unexpected increases in aboveground net primary productivity and altered ecosystem function, including increased nitrogen availability and cycling. These shifts are well documented, however many previous studies have been observational, focused on a single plant species, or have not examined belowground microbial communities. I combined field and experimental techniques to examine changes in productivity and ecosystem function, and the abundance of ammonia- oxidizing bacteria (AOB) for the exotic invaders Bromus tectorum, Centaurea stoebe, Euphorbia esula, and Potentilla recta. To quantify effects of these invasive species on N cycling and AOB abundance we compared soil from invaded and native communities in the field and in an experimental garden. AOB are bacteria responsible for a rate-limiting step in nitrification. We found that invasion was associated with increased abundance of AOB across all species of invader. For other variables, the magnitude of response to invasion varied by species, but we found in general invasion was associated with increased aboveground net primary productivity and soil nitrogen cycling. In addition results from the experimental garden suggest some species of invader may drive increases observed in the field. Finally we report on a novel relationship between aboveground net primary productivity and soil NO3-N indicating that invaders may drive ecosystem processes in ways different from native communities.

As wild species face anthropogenic stressors, they will either adapt, shift their geographic range, or decline, perhaps towards extinction. The relative scope of these responses has not been well studied, especially for climate change where geographic range shifts and population declines have been widely discussed but the potential for adaptation mostly ignored. Adaptation to anthropogenic stressors can occur through phenotypic plasticity and/or evolution. My thesis first establishes, based on field studies of wild snowshoe hares, a novel and high-profile stressor directly linked to climate change. The stressor arises from a decrease in snow duration due to climate change, which causes seasonal coat color molt of individual hares to become mismatched with their background. The immediate adaptive solution to this form of camouflage mismatch is phenotypic plasticity, either in phenology of seasonal color molts or in behaviors that reduce mismatch or its consequences. Based on nearly 200 snowshoe hares across a wide range of snow conditions and two study sites in Montana, USA that differed in elevation and climate, I found minimal plasticity in response to mismatch between coat color and background. I found that molt phenology varied between study sites, likely due to differences in photoperiod and climate, but was largely fixed within study sites where seasonal changes in phenology were limited across years of very different snow duration. Hares exhibited some plasticity in the rate of the spring molt in response to immediate snow conditions but temperature or snow cover were not strong modifiers of the white-to-brown molt phenology. I also found no evidence that individual hares modify their behavior in response to color mismatch. Hiding and fleeing behaviors and immediate microsite preference of hares were more affected by variables related to season, site, and concealment, than by color mismatch. Although hares do not appear to be responding to camouflage mismatch with behavioral plasticity, adaptation could also occur through evolutionary changes facilitated by natural selection. We found that the raw material for natural selection to act on does exist in our populations in the form of individual variation in coat color phenology and consequently in color mismatch. We also found high fitness costs of coat color mismatch, with hares suffering 3 to 7% lower weekly survival rates when mismatched against their background. Coupling these fitness costs to local estimates of increased seasonal color mismatch as snow duration decreases in the future, we predict that annual hare survival will decline up to 12% by mid- and 24% by late century. Such changes in survival are sufficient to cause increasing hare populations to decline strongly towards extinction, with annual population geometric growth rate decreasing by 11% (24%) by mid (late) century. We conclude that plasticity in molt phenology and behaviors in snowshoe hares is insufficient for adaptation to camouflage mismatch, and that potential adaptive responses to future climate change will have to be facilitated by natural selection. These results form the basis for future work to evaluate whether evolution by natural selection can operate fast enough to prevent decline of this species.