Knowledge of reproduction in the river otter, Lutra canadensis, and of the factors which control the reproductive cycle, is limited. The reproductive biology of river otters in the marine environment of British Columbia, and some of the factors which may influence their reproductive cycle, in particular, the effect of photoperiod, were examined. The changes that occurred in the anatomy, histology and endocrinology of the annual reproductive cycle were determined in wild (226 male, 146 female) and captive (9 male, 5 female) otters. Reproductive cycles were similar in both groups. As in the fresh-water environment, coastal otters are seasonal breeders with a prolonged, obligatory period of embryonic diapause prior to implantation. Changes were similar to those reported in other mustelids. In males, development of the seminiferous tubules was divided into a series of nine distinct phases used to quantify the degree of reproductive activity present. Testosterone concentrations were highly correlated to changes in testicular activity, and fell into the low end of the range of concentrations seen in mustelids. Vaginal smear types were found to identify correctly the reproductive state of female otters. Estradiol concentrations of captive otters were highly variable, but the values obtained and the pattern of secretion were similar to those of other carnivores. Although estradiol levels of captive otters were reduced in the final two years of the study, normal ovarian development occurred. During pregnancy, progesterone concentrations corresponded to changes observed in luteal cell cytology. I present evidence suggesting that female otters are monestrous, induced ovulators. The timing of reproductive events of otters in the marine environment was similar to those of otters inhabiting fresh water at comparable latitudes. Reproductive activity of males began in the late autumn and adults were capable of breeding from late January through mid-May. Females exhibited estrus from late February through mid-May, with the majority of matings probably occurring during March and April. After a nine to eleven month period of embryonic diapause, implantation occurred the subsequent February. Births occurred after an estimated two month gestation and parturient 1 otters mated during lactation. Male otters were sexually mature at the end of their second year. Only 55% of females bred at age class 2 and sexual maturity was delayed until the following year in the remainder of the females. Pregnancy rates were high among females over 3 years of age and ovulation rates were similar to those of other studies. To determine the influence of photoperiod on the timing of reproductive events, captive otters were exposed to increased photoperiods. With one exception, spermatogenesis and estrus occurred earlier under experimental conditions. My results suggest that the termination of embryonic diapause is also under photoperiodic control. Variations in temperature or food were not associated with changes in reproductive condition. This study suggests that photoperiod probably controls the timing of the reproductive cycle of otters in British Columbia. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (D. Min.)--Trinity International University, 2003. / Abstract. Includes bibliographical references (leaves 196-199).

Thesis (M.S.)--University of Wyoming, 2008. / Title from PDF title page (viewed on Dec. 7, 2009). Includes bibliographical references.

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 48-49).

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 183-207).

My research focuses on reconstructing past climate in southern Arizona using cave deposits called speleothems. However, this necessitates a broader perspective than simply a geochemical time series, and therefore, I also investigate modern cave systems using a combination of modeling and observational datasets. Finally, cave deposits are fundamentally non-renewable resources, and sampling for past climate reconstruction can be destructive, unlike other cave uses. My last investigation is focused on developing possible best practice recommendations for paleoclimate scientists and other cave stakeholders moving forward. We developed two new stalagmite records of past climate variability in southern Arizona over the past 7000 years. Past climate reconstruction from two caves (Cave of the Bells and Fort Huachuca Cave) highlights insolation control of southern Arizona hydroclimate from 7000-2000 years before present. Additionally, comparison between two stalagmites with different seasonal sensitivities uncovers a few eras of multi-decade long droughts in southern Arizona, which align with other regional reconstructions of past climates and elucidate forcings on Southwest paleoclimate as emergent from both external (insolation) and internal climate variability in the Pacific and Atlantic Ocean basins. Although the oxygen isotopic signal of cave calcite in speleothems is complex, agreement with these other records indicates that the speleothem records from these caves primarily record a climate signal.Modeling and monitoring of modern caves both helps us interpret paleoclimate records and enhances our understanding of cave systems in their own right. Modeling of Cave of the Bells dripwaters demonstrates the effect of storage and mixing on the dripwater oxygen isotope signal; non-climate processes can imprint on dripwater variability on multidecadal timescales. Monitoring shows that on very small spatial scales, every cave is different, and even sites within the same cave respond uniquely to surface climate. Most notably, calcite oxygen isotopic composition, used to reconstruct past climate, shows seasonal variability unrelated to dripwater and surface rainfall oxygen isotope variability. Substantial oxygen isotope disequilibrium is identified at numerous caves sites in southern Arizona, and this understanding aligns with a growing number of cave studies that demonstrate the long-held assumption of isotopic equilibrium in cave systems may not always be valid or that the way in which we define isotopic equilibrium insufficiently captures the variety of processes controlling the oxygen isotopic composition of speleothems. Overall, however, monitoring can identify stalagmites that are more sensitive to surface climate and less sensitive to these in-cave processes by identifying sites with dripwater variability responses to surface rainfall variability and sites that precipitate close to oxygen isotopic equilibrium. Finally, a major missing component in speleothem research is the fact that speleothems take thousands and sometimes hundreds of thousands of years to form. They are non-renewable resources on human timescales, and habitat for myriad microbes that have yet to be identified. Removal of speleothems for paleoclimate research is one of the only destructive uses of these deposits. With that in mind, I also analyze current methods of collecting speleothems and develop a framework based on two surveys of scientists and stakeholders to assist scientists and managers when evaluating potential methods of incorporating cave conservation into the speleothem sampling process. Thus, I approach caves from a variety of angles and timescales, from the past through the present to the future, illuminating caves as complex scientific and social systems.

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In 2011, several wild North American bumble bee pollinator species were reported to have declined by up to 96% in relative abundance in comparison to historic estimates, and one species was speculated to be extinct. None of these species have yet been documented to have recovered from these declines and additional species are now suggested to be at risk. Imperiled species in particular show increased specificity to narrow climatic envelopes, as opposed to putatively stable species. My dissertation describes patterns of population genetic diversity, structure, and gene flow pathways associated with climate variation and historical biogeography of bumble bees distributed in western North America. The results of my dissertation research suggests that (1) historic climate variability predicts contemporary patterns of population genetic structure and divergence in an economically important species, (2) color variability in bumble bees is likely associated with lineage diversification and phylogeography, (3) bumble bee community structure across evolutionary time is likely driven by Müllerian mimicry at narrow spatial scales, and (4) bumble bees inhabiting specialized ecological niches are associated with high levels of genetic fixation at regional spatial scales in the Pacific Northwest. The results of my research directly contribute to current efforts to effectively manage, conserve, and advocate for wild bumble bee pollinators in the context of global change.

Data on the Common and Purple Gallinules at the Welder Wildlife Foundation in South Texas indicated that resource partitioning between the two birds occurred. The objectives of this study were: (1) to compare differences in daily activities; (2) to investigate nesting habits; and (3) to measure physical characteristics of the two birds. Three methods of resource partitioning were utilized by the two gallinules. (1) Common Gallinules selected open water associated with sparse panicum and paspalum grasses while Purple Gallinules selected dense panicum and paspalum grasses. (2) Common Gallinules during migration and throughout the season shifted gradually from a sparse panicum and paspalum microhabitat to open water adjacent to sparse grasses. Purple Gallinules shifted from a sparse microhabitat during migration to an open panicum and paspalum microhabitat during courtship. However, during nesting, Purple Gallinules utilized a dense microhabitat. (3) Purple Gallinules placed nests in denser cover than Common Gallinules. Nests of Purple Gallinules were found at higher elevations above water than nests of Common Gallinules. Different patterns of diurnal activity, choices of different food items, differences in feeding methods, and differences in physical characteristics were partitioning mechanism factors also investigated and found not to be utilized by the two gallinules.

Streams and groundwaters interact in distinctly different ways during flood versus base flow periods. Recent research in the Upper San Pedro River using isotopic and chemical data shows that (1) near-stream, or 'riparian,' groundwater recharged during high streamflow periods is a major contributor to streamflow for the rest of the year, and (2) the amount of riparian groundwater derived from this flood recharge can vary widely (10-90%) along the river. Riparian groundwater in gaining reaches is almost entirely basin groundwater, whereas losing reaches are dominated by prior streamflow.This description of streamflow gives rise to the questions of (1) how much flood recharge occurs at the river-scale, and (2) subsequently, what is the relative importance of flood recharge and basin groundwater in maintaining the hydrologic state of the riparian system. To address these questions, a coupled hydrologic-solute model was constructed for 45 km of the Upper San Pedro riparian system.