No description available.

No description available.

No description available.

Almost half of the world�s mammal extinctions in the last two hundred years have occurred in Australia (Short and Smith 1994). The western barred bandicoot Perameles bougainville is one of a suite of species that is currently threatened with extinction, surviving only on two islands in Shark Bay, Western Australia. Reintroduction has been used as a tool in conservation biology to assist in the recovery of threatened species, such as the western barred bandicoot. The aims of this project were to 1) successfully reintroduce and establish a free-ranging mainland population of the western barred bandicoot at Heirisson Prong, Shark Bay, 2) contribute information on the biology of the species, its interactions with introduced species, and its likelihood of persistence as a reintroduced population in the longer-term, and 3) to provide recommendations to assist future reintroductions of the species. The first reintroduction of the western barred bandicoot from surviving remnant island populations to the mainland, some 60 years after its apparent mainland extinction, was from Dorre Island to Heirisson Prong in 1995. Animals were translocated initially to a predator-free refuge on Heirisson Prong, and then subsequently released to the 12 km2 peninsula where introduced predators (foxes Vulpes vulpes and feral cats Felis catus) had been controlled, but European rabbits Oryctolagus cuniculus had not. Despite a small founder number and high mortality of free-range bandicoots in the presence of a low-density feral cat population, the bandicoot population successfully established. The reintroduced population of western barred bandicoots provided an opportunity to study the biology of the species, and to compare it with the remnant island populations and other species of Australian bandicoot. Many population parameters were similar between the island and mainland western barred bandicoot populations, as well as between the western barred bandicoot and other bandicoot species, suggesting that the habitat at the reintroduction site is suitable for long-term persistence of the population. However, there were some notable differences. The western barred bandicoot is the smallest extant species of bandicoot, with fewer young per litter than recorded for other bandicoot species, adult sex ratios were closer to parity, animals reached sexual maturity later, and it is the only species of bandicoot where females are larger than males. Home range size is larger also than recorded for other species. Some of these differences may be explained in part by trade-offs between island dwarfism, lactational pressures, and nest defence. The nesting biology of the western barred bandicoot was studied at Heirisson Prong, including during periods of high and low densities of rabbits. Individuals of the species constructed and utilised nests in a similar fashion to other species of Australian bandicoot, nesting amongst litter underneath shrubs. The western barred bandicoot appeared to favour particular shrub species, especially when vegetation condition was poor due to rabbit damage, but displayed flexibility in being able to construct nests under a variety of shrub species where at least some surface litter was present. Grasses were used in nest construction only when rabbit density was low. Nests appear important for protection against temperature extremes and diurnal predators. Vegetation exclosures around three of the shrub species most commonly used by the western barred bandicoot for nest sites (Acacia ligulata, A. tetragonophylla and Melaleuca cardiophylla) were used to examine the impact of rabbits on vegetation on Heirisson Prong. A high-density rabbit population over the summer of 1997/98 caused in a decrease in canopy cover and the death of mature A. ligulata. Subsequent rainfall and low-density rabbit populations allowed A. tetragonophylla shrubs to recover their former structure, and M. cardiophylla to recover, but not to the same degree. The flexibility of western barred bandicoots in use of nest materials and their omnivorous diet may enable the species to survive in the face of habitat modification by rabbits. Population viability analysis was used to examine future options for the recovery of the endangered western barred bandicoot. Biological data from the Dorre Island and Heirisson Prong populations were input to the computer simulation program VORTEX. The western barred bandicoot populations were modelled under a variety of scenarios to examine the possible effects of changes in carrying capacity, founder population size, inbreeding depression, and the occurrence of drought and cat predation as catastrophes, on the probability of population extinction. This analysis highlighted the need for eradication of feral cats, above all other management actions. Cat predation was particularly potent when it acted through high loss of juveniles, as well as adult bandicoots. Predator control is considered critical for the long-term persistence of reintroduced populations of the western barred bandicoot. This study documents the first reintroduction of the endangered western barred bandicoot to mainland Australia. The population had been extant for four years at the completion of data collection for this thesis, in late 1999 and for over eight years at the finalisation of this thesis in July 2004. The knowledge gained from the reintroduction was used to discuss management recommendations and future options for the recovery of the species. The primary concern for reintroductions of this, and other species of bandicoots, remains the control of introduced predators. For long-term persistence of small, isolated populations, such as those of the western barred bandicoot at Heirisson Prong and the Arid Recovery Project at Roxby Downs in South Australia, and the eastern barred bandicoot Perameles gunnii at a range of sites in Victoria, the complete eradication of introduced predators is essential.

Testis tissue xenografting (TTX) provides a novel in vivo model for the study of testis function, and a previously-unavailable opportunity to produce spermatozoa in the grafts from immature donors of diverse species. The overall objectives of this thesis were to examine a number of factors that potentially affect the outcome of TTX, and to apply TTX using immature bison and deer donors as models for endangered ungulates. The objective of the first experiment was to examine the effects of recipient mouse strain, gender and gonadal status on the outcome of TTX. Eight small fragments of neonatal porcine testis tissue (~5 mg each) were grafted under the back skin of immunodeficient mice of different strains (SCID vs. nude), gender (male vs. female), and gonadal status (intact vs. gonadectomised), using a 2×2×2 factorial design (8 groups, n = 7 mice/group). The xenografts were recovered at 8 mo post-grafting and evaluated for gross and histological attributes. Gonadectomy of the recipients did not affect any of the measured outcomes of TTX (P > 0.05), and data were pooled into four groups based on recipient strain and gender. Overall, male recipient mice had grafts with higher mean (+SEM) recovery rate (97 ± 2.3% vs. 88 ± 2.4%, P = 0.004), weight (348 ± 26.3 vs. 104 ± 27.0 mg, P < 0.001), seminiferous tubular diameter (150 ± 3.3 vs. 108 ± 5.3 mg, P < 0.001), percentage of tubules containing spermatozoa (32 ± 3.2 vs. 6 ± 1.8%, P < 0.001), elongated spermatids (13 ± 1.4% vs. 4 ± 0.8%, P < 0.001), and round spermatids (10 ± 1.2% vs. 6 ± 1.1%, P = 0.006) than female mice. Overall, SCID mice had grafts with higher recovery rate (98 ± 2.4% vs. 87 ± 2.3%, P = 0.001), average weight (292 ± 27.0 vs. 160 ± 26.3 mg, P = 0.001), tubular density (44 ± 3.3 vs. 33 ± 2.1, P = 0.02), percentage of tubular cross-sections containing spermatocytes (27 ± 3.7% vs. 13 ± 2.3%, P = 0.003) than nude mice. Among the four groups of recipients, the grafts from male SCID mice had the highest weight (P < 0.05) and percentage of tubules containing spermatozoa (P < 0.05).<p> The objective of the second experiment was to evaluate the effect of using different numbers of donor testis tissue fragments on the outcome of TTX. Fragments of donor piglet testis tissue were grafted subcutaneously under the back skin of four groups of castrated male nude mice (n = 10/group). Each group of recipient mice received 2, 4, 8, or 16 fragments per mouse. Mice were sacrificed at 8 mo post-grafting, and xenografts were evaluated for physical growth and histological development. The relative weight of the vesicular gland (index) was also determined as a measure of bioactive androgen production by grafts in castrated recipient mice. The overall graft recovery rate was ~94% (range 86-98%) which did not differ among the groups (P > 0.05). The group of mice that received 16 testis tissue fragments had higher mean (+ SEM) graft weights (278 ± 39.4 vs. 106 ± 38.0, P = 0.02), total graft weight (2,443 ± 338.8 vs. 192 ± 76.2, P < 0.001), vesicular gland index (0.5 ± 0.06 vs. 0.1 ± 0.06, P = 0.007), and percentage of seminiferous tubules with round spermatids (11 ± 1.5 vs. 3 ± 1.3, P = 0.03) than the group of mice that received two testis tissue fragments. The objective of the third experiment was to assess the use to salvage testis tissue from neonatal/immature bison or deer donors using TTX into immunodeficient recipient mice as models for closely-related rare or endangered ungulates. Donor testis tissue fragments from two newborn bison calves (Bison bison bison) and a 2-mo-old white-tailed deer fawn (Odocoileus virginianus) were grafted under the back skin of gonadectomised nude mice (n = 15 and n = 7 for bison and deer groups, respectively, 8 testis fragments/mouse). To examine the potential effect of individual donors, we grafted four testis tissue fragments from one bison calf on one side of the recipient and four fragments from the second bison calf on the other side. Single grafts were surgically removed from representative recipient mice every 2 mo for up to 16- and 14 mo post-grafting, for bison and deer groups, respectively. The overall graft recovery rates were 69% and 63% for bison and deer groups, respectively. For bison grafts, a donor effect on efficiency of spermatogenesis was also observed. The weight of bison testis tissue xenografts increased (P < 0.02) ~4-fold by 2 mo and ~10-fold by 16 mo post-grafting, and gradual maturational changes were evident in the form of seminiferous tubule expansion starting at 2 mo, first appearance of spermatocytes at 6 mo, round spermatids at 12 mo, and elongated spermatids at 16 mo post-grafting. Testis tissue xenografts from donor white-tailed deer also showed a gradual development starting with tubular expansion by 2 mo and presence of spermatocytes by 6 mo post-grafting, round and elongated spermatids by 8 mo, followed by fully-formed spermatozoa by 12 mo post-grafting. The timing of complete spermatogenesis roughly corresponded to the reported timing of sexual maturation in these species.<p> Taken together, the findings in this thesis suggest that male SCID mice provide a more suitable recipient model for TTX with neonatal porcine testis tissue; recipient mice can be grafted with as many as 16 testis tissue fragments for optimal results; and that TTX is a feasible strategy for salvaging genetic materials from immature males of rare or endangered ungulates that die prematurely.

Testis tissue xenografting (TTX) provides a novel in vivo model for the study of testis function, and a previously-unavailable opportunity to produce spermatozoa in the grafts from immature donors of diverse species. The overall objectives of this thesis were to examine a number of factors that potentially affect the outcome of TTX, and to apply TTX using immature bison and deer donors as models for endangered ungulates. The objective of the first experiment was to examine the effects of recipient mouse strain, gender and gonadal status on the outcome of TTX. Eight small fragments of neonatal porcine testis tissue (~5 mg each) were grafted under the back skin of immunodeficient mice of different strains (SCID vs. nude), gender (male vs. female), and gonadal status (intact vs. gonadectomised), using a 2×2×2 factorial design (8 groups, n = 7 mice/group). The xenografts were recovered at 8 mo post-grafting and evaluated for gross and histological attributes. Gonadectomy of the recipients did not affect any of the measured outcomes of TTX (P > 0.05), and data were pooled into four groups based on recipient strain and gender. Overall, male recipient mice had grafts with higher mean (+SEM) recovery rate (97 ± 2.3% vs. 88 ± 2.4%, P = 0.004), weight (348 ± 26.3 vs. 104 ± 27.0 mg, P < 0.001), seminiferous tubular diameter (150 ± 3.3 vs. 108 ± 5.3 mg, P < 0.001), percentage of tubules containing spermatozoa (32 ± 3.2 vs. 6 ± 1.8%, P < 0.001), elongated spermatids (13 ± 1.4% vs. 4 ± 0.8%, P < 0.001), and round spermatids (10 ± 1.2% vs. 6 ± 1.1%, P = 0.006) than female mice. Overall, SCID mice had grafts with higher recovery rate (98 ± 2.4% vs. 87 ± 2.3%, P = 0.001), average weight (292 ± 27.0 vs. 160 ± 26.3 mg, P = 0.001), tubular density (44 ± 3.3 vs. 33 ± 2.1, P = 0.02), percentage of tubular cross-sections containing spermatocytes (27 ± 3.7% vs. 13 ± 2.3%, P = 0.003) than nude mice. Among the four groups of recipients, the grafts from male SCID mice had the highest weight (P < 0.05) and percentage of tubules containing spermatozoa (P < 0.05).<p> The objective of the second experiment was to evaluate the effect of using different numbers of donor testis tissue fragments on the outcome of TTX. Fragments of donor piglet testis tissue were grafted subcutaneously under the back skin of four groups of castrated male nude mice (n = 10/group). Each group of recipient mice received 2, 4, 8, or 16 fragments per mouse. Mice were sacrificed at 8 mo post-grafting, and xenografts were evaluated for physical growth and histological development. The relative weight of the vesicular gland (index) was also determined as a measure of bioactive androgen production by grafts in castrated recipient mice. The overall graft recovery rate was ~94% (range 86-98%) which did not differ among the groups (P > 0.05). The group of mice that received 16 testis tissue fragments had higher mean (+ SEM) graft weights (278 ± 39.4 vs. 106 ± 38.0, P = 0.02), total graft weight (2,443 ± 338.8 vs. 192 ± 76.2, P < 0.001), vesicular gland index (0.5 ± 0.06 vs. 0.1 ± 0.06, P = 0.007), and percentage of seminiferous tubules with round spermatids (11 ± 1.5 vs. 3 ± 1.3, P = 0.03) than the group of mice that received two testis tissue fragments. The objective of the third experiment was to assess the use to salvage testis tissue from neonatal/immature bison or deer donors using TTX into immunodeficient recipient mice as models for closely-related rare or endangered ungulates. Donor testis tissue fragments from two newborn bison calves (Bison bison bison) and a 2-mo-old white-tailed deer fawn (Odocoileus virginianus) were grafted under the back skin of gonadectomised nude mice (n = 15 and n = 7 for bison and deer groups, respectively, 8 testis fragments/mouse). To examine the potential effect of individual donors, we grafted four testis tissue fragments from one bison calf on one side of the recipient and four fragments from the second bison calf on the other side. Single grafts were surgically removed from representative recipient mice every 2 mo for up to 16- and 14 mo post-grafting, for bison and deer groups, respectively. The overall graft recovery rates were 69% and 63% for bison and deer groups, respectively. For bison grafts, a donor effect on efficiency of spermatogenesis was also observed. The weight of bison testis tissue xenografts increased (P < 0.02) ~4-fold by 2 mo and ~10-fold by 16 mo post-grafting, and gradual maturational changes were evident in the form of seminiferous tubule expansion starting at 2 mo, first appearance of spermatocytes at 6 mo, round spermatids at 12 mo, and elongated spermatids at 16 mo post-grafting. Testis tissue xenografts from donor white-tailed deer also showed a gradual development starting with tubular expansion by 2 mo and presence of spermatocytes by 6 mo post-grafting, round and elongated spermatids by 8 mo, followed by fully-formed spermatozoa by 12 mo post-grafting. The timing of complete spermatogenesis roughly corresponded to the reported timing of sexual maturation in these species.<p> Taken together, the findings in this thesis suggest that male SCID mice provide a more suitable recipient model for TTX with neonatal porcine testis tissue; recipient mice can be grafted with as many as 16 testis tissue fragments for optimal results; and that TTX is a feasible strategy for salvaging genetic materials from immature males of rare or endangered ungulates that die prematurely.

Using four AFLP markers and seven polymorphic microsatellite loci, we examined the genetic structure of the rare and endangered Spiranthes parksii Correll (Orchidaceae). Spiranthes parksii is not distinguishable from sympatric S. cernua (L.) Rich based on these data, though low levels of polymorphisms exist within both. These low levels of genetic diversity are likely a result of high levels of agamospermic reproduction through adventitious embryony. These results suggest that both S. parksii, as well as the sympatric, open flower form of S. cernua, are products of the more widely distributed S. cernua complex. Further, another local form of S. cernua, distinguished by its tendency to produce closed flowers is genetically distinct from both S. parksii, as well as the openflower form of S. cernua, as shown by AFLPs and microsatellite loci. This is the first known set of microsatellite primers developed specifically for use in Spiranthes. The application of these markers may be used to address other unresolved relationships among species of Spiranthes, many of which are also endangered or have populations in decline.

Thesis (PhD.)--University of Canberra, 2007. / Includes bibliography (p. 152-176)

Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 520-556). Also available on the Internet.