Animal & Avian Sciences
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Item BIOLOGY AND MANAGEMENT OF REPRODUCTION IN CAPTIVE CRANES(2017) Brown, Megan Elizabeth; Keefer, Carol L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)There are 15 species of cranes found throughout the world, 11 of which are listed as vulnerable or endangered. All 15 species are currently managed in captivity; however, with increased threats to wild crane habitats and populations, ex situ management becomes increasingly critical as a hedge against extinction. Reproduction and the production of offspring is required to ensure self-sustaining populations managed in ex situ conservation breeding programs. However, current reproductive success of the endangered whooping crane (Grus americana), as well as other species, maintained ex situ is suboptimal and hinders population sustainability and reintroduction goals. The objectives of this dissertation were to 1) develop a cryopreservation protocol for crane semen to improve genetic management in endangered cranes, 2) investigated seasonal hormone patterns and measured the impact of captive environment on hormone production and reproductive behaviors, and 3) retrospectively examine the effect of bird as well as management variables on egg fertility in whooping cranes. The findings demonstrated that 1) sperm of both whooping and white-naped crane performed better following cryopreservation when dimethyl-sulfoxide is utilized as a cryoprotectant, 2) seasonal fluctuations occur in hormone production in both sexes, while addition of a water feature to captive enclosures stimulated reproduction in females, and 3) female specific variables had the greatest influence on probability of egg fertility. Overall findings will help whooping crane management Continued research into the mechanisms controlling sperm sensitivity to cryo-damage, egg production, and fertilization are necessary to mitigate reproductive problems in captive crane species.Item Population Declines and Genetic Variation: Effects of Serial Bottlenecks(2015) Callicrate, Taylor Eilers; Song, Jiuzhou; Fleischer, Robert C; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Islands foster unique biodiversity, yet also present biogeographic limitations that impose increased risk for population extinction through demographic and genetic constraints and decreased probability of surviving a catastrophe. Of particular interest, especially with regard to endangered species, is the genetic response of insular species to severe population declines or translocations. Both types of events, considered population bottlenecks, are expected to reduce genetic variation, and correspondingly, adaptive potential. For these reasons, it is important to understand how bottlenecks interact with insular population dynamics to affect genetic diversity. I used a combination of a laboratory model experiment and population genetics study of an in situ bottleneck in an endangered species to investigate how quantitative and molecular genetic variation are affected during bottlenecks. I used a laboratory animal model (red flour beetle, Tribolium castaneum) to compare how quantitative genetic variation is affected if a serial bottleneck occurs in a novel versus familiar environment. The experiment was designed to model a founder event or translocation to a new island with a novel environment. I found that phenotypic and additive variance for a quantitative trait were larger following a bottleneck occurring in the novel environment, suggesting that the novel environment could improve adaptive potential in bottlenecked populations. Next, I used molecular genetic markers to assess variation and signatures of selection in the Laysan finch (Telespiza cantans), a Hawaiian honeycreeper endemic to a small Northwestern Hawaiian island. Laysan finches experienced a major bottleneck on Laysan in the early 20th century, followed by a translocation and series of founder events as populations were established on the islets of Pearl and Hermes Reef (PHR) in the 1960s – 70s. I found that, contrary to expectation, bottlenecked Laysan finch populations did not show declines in genetic variation and were not differentiated as a result of genetic drift. These results are potentially caused by insular demographic dynamics. I identified loci with extreme differentiation between modern populations, potentially indicating genomic signals of selection. These regions could be important for adaptation to the novel environment on PHR and are candidates for future study.Item Investigation of spermatozoal metabolism and substrate utilization in domestic and non-domestic felids(2015) Weiner, Halli Sigal; Keefer, Carol L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cryopreservation of spermatozoa is a critical aspect of assisted reproduction. However in most cases, this process causes diminished spermatozoal function and low cellular survival. The effects of cryopreservation are further compounded in spermatozoa from individuals with disorders known to affect fertility. Teratospermia, characterized by the ejaculation of >60% morphologically abnormal spermatozoa, is one such disorder. Sperm from individuals with this condition exhibit reduced motility, impaired mitochondrial function, and a reduced ability to bind, penetrate, and fertilize an oocyte compared to sperm from normospermic males. Interestingly, even spermatozoa from teratospermic males that appear normal exhibit reduced functional capacity and following cryopreservation all cells are further impaired. More than 90% of felid species are affected by this condition, and it is prevalent among humans. Previous research suggested that impaired sperm metabolism in cheetahs – a ubiquitously teratospermic species – contributes to their poor cryosurvival and function, but the specific mechanisms are unknown. In this research, we hypothesized that inherent differences exist between the substrates and metabolic pathways utilized by sperm from normospermic and teratospermic individuals and on a species-specific basis. Gas chromatography - mass spectrometry (GC-MS) was used to investigate felid sperm metabolism using semen collected from domestic cats (Felis catus), cheetahs (Acinonyx jubatus), and clouded leopards (Neofelis nebulosa). The main objectives of this research were to: 1) characterize the metabolome of spermatozoa and seminal fluid; 2) investigate the role of β-oxidation in sperm motility and metabolism; and 3) interrogate the significance of specific metabolic pathways using metabolic activity profiling and heavy isotope tracers. Using GC-MS enabled the identification of metabolites which were unique to each species and sperm status (normospermic vs. teratospermic). Additionally, treatment of sperm with a β-oxidation inhibitor caused impaired motility in cheetah - but not domestic cat or clouded leopard - spermatozoa. Finally, fluxomic analysis demonstrated that glucose, fructose, and pyruvate are metabolized by felid sperm, but pathway utilization is species-specific. This is the first study to utilize a metabolomic and fluxomic approach to studying felid sperm, and the results of these studies illustrate the complexity of sperm metabolism on a species-specific basis. Understanding metabolic pathway activity in these cells will aid in the development of improved assisted reproduction techniques that may better facilitate sperm function and survival.Item MULTIDISCIPLINARY APPROACH TO UNDERSTANDING THE POOR REPRODUCTION IN THE WHOOPING CRANE (GRUS AMERICANA)(2013) Brown, Megan Elizabeth; Songsasen, Nucharin; Keefer, Carol L; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Reproductive success of the endangered whooping crane (Grus americana) maintained ex situ is suboptimal. The main goals of this multidisciplinary investigation are to advance the understanding of whooping crane reproduction and identify potential causes of poor reproductive success in a captive colony. The specific objectives include (Study 1) determining overall seminal characteristics and examine the influences of inbreeding, age, and stages of breeding season on seminal quality in captive birds and (Study 2) utilizing non-invasive endocrine monitoring to longitudinally assess gonadal and adrenal steroids of bird pairs with various reproductive outcomes and evaluating the relationship between hormones and crane behaviors. Our findings demonstrate that (1) there is no relationship between inbreeding coefficient or age and seminal quality of the whooping crane and (2) stage of breeding season impacted seminal output and characteristics. Overall estradiol concentrations and reproductive behaviors, but not glucocorticoid levels, were also key determinants to successful reproductive output.Item Characterization and Control of Aggression and Reproduction in the Male Clouded Leopard (Neofelis nebulosa)(2012) DeCaluwe, Heather Burton; Ottinger, Mary Ann; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Clouded leopards are a striking and elusive cat species whose secretive nature has made it difficult to gather information on population statistics and behavior in the wild, where the population is in decline. While captive populations are intended as a hedge against extinction, breeding clouded leopards ex situ has been a challenge, primarily due to extreme male aggression toward females. Despite the importance of aggression in this species, there has as yet been no systematic study characterizing the basis of aggressive episodes. Two mechanisms seem to underlie the aggressive behavior in clouded leopards: degree of anxiety and circulating testosterone levels. Three studies were conducted to characterize mechanisms modulating aggression in male clouded leopards. In Study 1, sixteen adult male clouded leopards were categorized as `anxious' or `calm' using a keeper questionnaire and fecal endocrine (androgen and glucocorticoid) profiles; these measures were correlated with behavior rates and frequencies before, during, and after a series of behavioral reaction tests aimed at assessing an individual's response to stress-inducing situations. In Study 2, the behavioral and endocrine responses to the same tests were compared in the same clouded leopards following three treatments: 1) an anxiety-reducing psychotropic drug (clomipramine, n = 4); 2) a gonadotropin releasing hormone agonist (deslorelin, n = 5), or 3) no treatment (n = 4). In Study 3, the long-term effects of the drug treatments on spermatogenesis and hormone concentrations were compared in clouded leopards (n = 2/treatment) and domestic cats (n = 5/treatment), a model for non-domestic felid reproduction. Studies revealed important findings about the basis of aggressive behavior in male clouded leopards. First, two of the behavioral reaction tests - `mirror image stimulation' and `unfamiliar people' - were effective tools for evaluating temperament and eliciting a behavioral response. Second, treatment with both clomipramine and deslorelin reduced anxious and aggressive behaviors (e.g. `tail flicking' and `growling') indicating multiple physiological mechanisms likely modulate aggression in this species. Finally, deslorelin temporarily suppressed hormone concentrations and reproductive function, while clomipramine had no clear effect on either. Ultimately, this information provides important tools for improving male-female pairing success and the overall management of captive clouded leopards.