The reproductive cycle of Miniopterus schreibersii is modified as a consequence of a period of torpor/hibernation over the winter months. This bat is one of three genera which employ the reproductive strategy of delayed implantation in which the blastocyst remains free in the uterine lumen during the winter months. Spermatogenesis is initiated in February, with spermiogenesis occuring in March. Copulation, ovulation and fertilization takes place between March and May after which the testes regress and remain in an inactive condition until the following summer. Activity in the accessory gland complex is initiated in March and continues until early June. Plasma testosterone concentrations reach a peak in May, decline over the winter months and reach a second, unexplainable peak in October. Leydig cells are secretorily active in February/early March after which they undergo vacuolation and final degeneration. The question of the life cyle of Leydig cells is addressed and an increase in a certain cell after Leydig cell activity suggests that this cell type may be the precursor of Leydig cells.

Chromosomal rearrangements have been hypothesized to be the cause of reproductive isolation leading to speciation in diverse taxa. One model for chromosomal speciation, speciation by monobrachial centric fusions, is thought to apply to various groups of mammals, including members of the bat genus Rhogeessa (Chiroptera: Vespertilionidae). Specifically, this model has been proposed to account for diversification within the R. tumida species complex. This species group exhibits a high degree of karyotypic variation, with little to no morphological differentiation between species. By examining phylogenetic data derived from DNA sequences of maternal, paternal and bi-parentally inherited markers, I investigate phylogenetic relationships of species within Rhogeessa and test expectations of the model of speciation by monobrachial centric fusions on members of the R. tumida complex. If chromosomal fusions caused speciation in Rhogeessa, I expect to see patterns of reproductive isolation between species differing by monobrachial fusions, and therefore each chromosomal form should be a monophyletic group. My data generally follow this pattern, with the exception of potential evidence for historical hybridization between R. tumida (2n = 34) and R. aeneus (2n = 32), where none is expected under the model. There is no evidence, however, of ongoing or recent hybridization between any taxa differing karyotypically. Moreover, the speciation model predicts that all populations which contain the same set of chromosomal fusions should freely interbreed, if chromosomal rearrangements are the sole cause for reproductive isolation. My data also show an exception to this prediction based on the observation of multiple genetic lineages of karyotypically identical R. tumida (2n = 34). This observation indicates that chromosomal differences cannot account for genetic diversification between the different lineages of R. tumida. Phylogeographic analyses indicate that lineages within this species could have diverged due to differences in habitat preferences. Overall, these data are generally consistent with speciation having occurred via reproductive isolation caused by chromosomal fusions. However, it does not appear that these rearrangements have caused complete reproductive isolation due to the evidence consistent with historical hybridization between Rhogeessa tumida and R. aeneus. The chromosomal mechanism is also not likely to be the only means by which diversification has taken place in Rhogeessa. Geographic factors have apparently influenced genetic divergence as well.

Postnatal growth and development in the little brown bat, Myotis lucifugus, was characterized for two latitudinally separated populations to examine effects of the length of the growing season . Bats from New Hampshire (43°N) and bats experiencing a shorter and colder growing season in Alberta (54°N), were compared with respect to birth size and growth rate (as measured by forearm length and body mass), flight development, ontogeny of thermoregulation, body composition, and the allometric growth of body parts. Alberta bats were shown to grow more slowly, and flight development was somewhat delayed. However, Alberta bats were born larger, suggesting that when growth is slowed by colder growing conditions, selection favors greater prenatal investment allowing Alberta juveniles to reach the size required to survive the first hibernal period. Thermoregulatory development is delayed in Alberta juveniles, indicating that these bats defer investment in thermogenesis until a critical point in postnatal growth . A model 1s presented defining this critical point by relating thermogenic ability and conductance to the timing of onset of homeothermy. Analysis of body composition revealed that differences between the two populations were primarily manifested in the proportions of lean dry mass and water. Fat contributed more to energy density among New Hampshire bats, suggesting that Alberta bats allocate more energy to structural development than energy storage during early growth. These results, coupled with evidence of delayed reproduction in Alberta bats, indicate that growth 1s constrained by the shorter, colder Alberta growing season. Geographic variation 1n adult size and sexual dimorphism was investigated in light of the differences in offspring development. Adult skull and wing variables indicate that this species conforms to Bergmann's rule in that Alberta bats are larger. While sexual dimorphism is not pronounced in New Hampshire, it is evident in Alberta bats. The most striking result 1s the larger wing size of Alberta females. Much of the variation in M. lucifugus adults can be explained by selection for larger offspring which affects female morphology. A new hypothesis incorporating the effects of selection during offspring development is advanced to explain patterns of geographic variation 1n size and sexual dimorphism among birds and mammals with broad latitudinal distributions.

No description available.

A maternity colony of the big brown bat (Eptesicus fuscus) was observed from 21 May 1992 to 12 October 1992. The colony consisted of approximately 110 females at the beginning of the study, and about 180 bats following birth of the young. Bats were observed at emergence to gather data on factors affecting initial emergence: light intensity, temperature, relative humidity, barometric pressure, wind speed, cloud cover, and moon phase. Light intensity and cloud cover apparently are the factors most affecting the variation between initial emergence and sunset. / Department of Biology

Thesis (M.S.)--University of Tennessee, Knoxville, 2010. / Title from title page screen (viewed on July 20, 2010). Thesis advisor: Gary McCracken. Vita. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

No description available.

Chaerephon (Dobson, 1874), an Old World genus belonging to the family Molossidae, is part of the suborder Vespertilioniformes. Members of this genus are distributed across mainland Africa (sample sites; Tanzania, Yemen, Kenya, Botswana, South Africa and Swaziland), its offshore islands (Zanzibar, Pemba and Mozambique Island), Madagascar and the surrounding western Indian Ocean islands (Anjouan, Mayotte, Moheli, Grande Comore, Aldabra and La Reunion). A multifaceted approach was used to elucidate the phylogenetic and population genetic relationships at varying levels amongst these different taxa. Working at the subspecific level, I analysed the phylogenetics and phylogeography of Chaerephon leucogaster from Madagascar, based on mitochondrial cytochrome b and control region sequences. Cytochrome b genetic distances among C. leucogaster samples were low (maximum 0.35 %). Genetic distances between C. leucogaster and C. atsinanana ranged from 1.77 % to 2.62 %. Together, phylogenetic and distance analyses supported the classification of C. leucogaster as a separate species. D-loop data for C. leucogaster samples revealed significant but shallow phylogeographic structuring into three latitudinal groups (13º S, 15 - 17º S, 22 - 23º S) showing exclusive haplotypes which correlated with regions of suitable habitat defined by ecological niche modelling. Population genetic analysis of D-loop sequences indicated that populations from Madagascar have been expanding since 5 842 - 11 143 years BP. At the infra-generic level, I carried out analyses of sequences of the mitochondrial cytochrome b gene and control region, and the nuclear RAG2 region, to resolve the evolutionary history and taxonomy of the C. pumilus species complex from Africa and the western Indian Ocean islands. The nominate form comprised C. pumilus from Massawa, Eritrea, and this was genetically distinct from all other forms of Chaerephon. Our molecular evidence does not support that the syntype of C. limbatus and the holotypes of C. elphicki and C. langi and topotype of C. naivashae are specifically distinct from C. pumilus s.s. There is evidence of introgression of both C. pusillus and C. pumilus s.l. (south eastern Africa) mitochondrial haplotypes into C. leucogaster. The C. pumilus species complex has several attributes of a ring species, but appears to differ from this model in some important respects. It occurs on the African mainland and western Indian Ocean Islands, including Madagascar, ringing a potential barrier to gene flow, the Mozambique Channel. The taxa within the species complex form a ring in which the differentiated terminal forms, C. pusillus and C. leucogaster, occur in sympatry on Mayotte (Comoro Islands). Although there is evidence of isolation by distance around the ring, there is also a relatively high degree of genetic structure and limited gene flow. It appears that the island-based component species may have differentiated in allopatry, with some gene flow by over water dispersal, whereas the African mainland species may have differentiated through isolation by distance. A further study was aimed at re-examining the phylogeny of C. pumilus sensu lato from south eastern Africa based on a considerably larger sample set with a wider geographic range; I confirmed the previously-reported phylogenetic structure, and identified an additional strongly-supported control region clade. Discriminant Function Analysis based on four echolocation parameters could not discriminate between these clades. The hypothesised existence of cryptic species with distinct echolocation characteristics was not supported. Indices of diversity and neutrality, combined with a ragged multimodal mismatch distribution, are inconsistent with demographic expansion of a single C. pumilus south eastern African population and suggest that the control region lineages are stable populations at demographic equilibrium that were established during the late Pleistocene between 60 000 and 13 000 years ago. Further, more variable markers (microsatellites) were employed for finer-scale resolution of population genetic structure among the five genetic lineages of C. pumilus sensu lato found in the Durban area of KwaZulu-Natal, and to search for hybridization between these lineages. We recovered strong mitochondrial genetic structure, with 90% of the molecular variance occurring among four phylogenetically-defined groups, and a high significant Fst (0.897). Microsatellite data recovered three admixed populations with 3% of the nuclear variance occurring among populations, and global (Fst=0.037) and pairwise Fst values among populations were low and not significant. This is indicative of little genetic structure among the groups of C. pumilus s.l., which appear to comprise a single interbreeding population. Such high levels of mitochondrial genetic structure in the absence of significant nuclear structure are consistent with social isolation mechanisms such as female philopatry, and may reflect introgression of mitochondrial genes due to past hybridisation events with mitochondrially-distinct forms from outside the sampled area. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2013.

Thesis (Ph.D.)--University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2006. / "January 2006" Includes copies of author's previously published works. Includes bibliographical references. Also available in print form.