Thesis (Ph. D.)--Bryn Mawr College, 1918. / Vita. Bibliography: p. 51-53.

Diss. - Bryn Mawr College. / Bibliography: p. 51-53.

1) An investigation was undertaken into the various activity rhythms found in the larvae of Myrmeleon obscurus (Neuroptera, Myrmeleontidae). Pit construction was used as the criterion of activity. 2) The capacity sensitive electronic circuit used to monitor the daily pit building activity is described. 3) Various factors affecting the size of the pits constructed by ant-lion larvae were investigated. Pit size was found to be correlated with the size of the larvae, larger larvae constructing bigger pits. Population size was also shown to have an effect, since the more crowded the animals were the smaller and closer together their pits became. The death rate due to competition between the larvae also increased as the ant-lions became more crowded. 4) Feeding frequency also affected pit size. Ant-lions which were starved constructed very small pits. 5) Pit size was affected by the texture of the sand, maximal pit size being attained in sand with a grain size of between 353 μ and 211 μ. This was shown to be the most abundant grain size in sand from the natural habitat. In sand coarser or finer than this, pit size was reduced. 6) Generally smaller pits were constructed at lower temperatures, but this response depended largely on the lunar cycle. The upper and lower critical limits for pit construction were found to be 11° C and 42° C. Below and above these temperatures no pits were constructed, although the ant-lions remained alive. 7) Daily destruction of the pits decreased the pit size. 8) The existence of the daily pit building activity rhythm, which occurs at dusk, was demonstrated in individuals and in populations of ant-lion larvae. This rhythm was studied using the capacity sensitive circuit, and also by direct observation of groups of animals over a 24 hour period. 9) The daily activity rhythm appeared to be endogenous, since it continued for at least a month both in constant light and in constant dark. The rhythm was altered by reversals in the daily light-dark cycle, and it was concluded that light was the main phase setting factor. 10) An attempt was made to determine the location of the "clock" or "clocks" controlling the daily activity rhythm. This was investigated by chilling the heads of individual ant-lions with a fine copper wire, and also by chilling large groups of animals in the refrigerator. From these experiments no definite conclusions could be drawn about the location of the "clock". 11) The existence of a lunar pit building cycle was demonstrated in both field and laboratory populations of ant-lions. Maximal pit size was attained at full moon. Very low temperatures were found to suppress these lunar peaks. 12) The lunar pit building rhythm was shown to be endogenous, since it continued for at least two months in constant dark and one month in constant light. 13) The lunar pit building rhythm of very young larvae was investigated, and it was shown that while larvae which hatched in the field appeared to possess a lunar rhythm, larvae which were hatched in the laboratory did not have a rhythm. It was therefore concluded that the light of the moon was necessary to establish the lunar rhythm. 14) Some possible explanations for the lunar cycle were investigated experimentally. It was concluded that the lunar rhythm was not related to the number of prey present at various times of the lunar cycle or to the spacing of the animals in their habitat. The lunar rhythm was shown to be due to the combination of a lunar day activity rhythm and a solar day activity rhythm. 15) Some aspects of the daily rhythm are discussed, and this rhythm is compared with those found in other insects. Probable functional reasons for the rhythm are presented. Summary, p. 133-136.

The biology of southern African Myrmeleontidae and Nemopteridae (Neuroptera, Myrmeleontoidea) was studied with special emphasis on the nemopterid subfamily Crocinae. The superfamily Myrmeleontoidea is considered to be a monophyletic group derived from ancestors similar to the family Nymphidae. The Myrmeleontidae and Nemopteridae are the most highly evolved families, and the Nemopteridae have a sistergroup relationship with the other four myrmeleontoid families. Within the Nemopteridae, the Crocinae are considered more advanced than the subfamily Nemopterinae. An account of previous work on the two families is presented: literature relating to the Myrmeleontidae is catalogued in appendix 2 and publications dealing with the Nemopteridae are surveyed in the text . Biological and morphological information derived from the immature stages as well as the adults was used in the systematic study of the two families. The geographical distribution and phylogeny of the Myrmeleontoidea is discussed with particular reference to the Myrmeleontidae and Nemopteridae. The Myrmeleontidae have a world wide distribution whilst the Nemopteridae are more restricted, being limited to the arid and semi-arid regions of the world. It is concluded that the two families originated on Gondwanaland, and their present distribution is explained on the basis of evidence provided by plate tectonics. In southern Africa, the Myrmeleontidae show two distributional trends: there is a distinct western fauna including many endemics and an eastern fauna which comprises taxa with a wide distribution in central and east Africa, extending their ranges into the eastern parts of the subregion. The Nemopteridae occur predominantly on the western side of the subcontinent and over 90% of the species are endemic to southern Africa. A systematic revision of the southern African Crocinae is presented and summarized in a set of illustrated keys to the adults and larvae. There are now ten known crocin species in four genera from the subregion, four species being described for the first time in this thesis. The larvae of all ten species and the eggs of seven, have been correlated with the adults and are described. Two crocin genera, Concroce and Thysanocroce, have larvae with short prothoraxes, whilst those in Laurhervasia and Tjederia are elongated. Larvae of the first two genera live in plant detritus under rocks and in crevices whereas larvae of the latter two genera inhabit small dusty caves. These findings on the Myrmeleontidae and Nemopteridae are discussed in the context of general systematic theory, phylogeny and zoogeography.

From Introduction: Larvae of the families Myrmeleontidae, Neuroptera, (ant-lions) and Rhagionidae, Diptera, (worm-lions) all live in hot dry sand. Many of the ant-lion larvae and all the worm-lion larvae, construct small conical pits in the sand which are used for the capture of prey (Haub, 1942; Youthed and Horan, 1969a). Those ant-lion larvae which do not construct pits lie in wait for their prey just below the surface of the sand.

Please read the abstract in the section oofront of this document / Thesis (PhD (Zoology))--University of Pretoria, 2007. / Zoology and Entomology / PhD / unrestricted

Predation by large fissipeds is examined using the specific example of the African lion. It is found that the lion is able to adjust its strategy and tactics at each phase of prey capture (search, stalk, attack, and subdue) so as to achieve a consistently high overall capture success with different prey and conditions. / Science, Faculty of / Zoology, Department of / Graduate

While many studies have been done on Lions, relatively little work has been conducted on how they interact with local habitats and the factors of importance in determining home ranges and territories. The interactions between predators and patchily distributed resources and the basic tenets of Ideal Free Distribution theory have been used in this study as the basis in explaining how lions distribute themselves in space and why they choose particular areas above others in regards territory location. The study was conducted in the Hluhluwe-Umfolozi Park, South Africa and involved the use of historical lion sightings data recorded between the years 1973 and 1999 inclusive. A variety of potential explanatory variables including vegetation, topography, rainfall, main river distribution, roads, hyaena den locations and prey were used in developing logistic models which were then used to predict areas most likely to be colonised by lion. Model predictions were tested against independently collected validation data from an introduced pride . Modelling was conducted at a 1km² grid cell size. In total, seventeen models were formulated for four lion variables, namely cubs, adult females in groups of two or more, adult males seen with adult females and adult males only. All models accounted for a significant amount of deviance (p<0.001) except for one cub model (p=0.003). Models which performed best in correlations with validation data were those formulated for adult females in groups of two or more and cubs (p<0.05). Variables of importance in these models included distance from main rivers and presence/absence of public roads. Preferences for travelling on roads were influenced by vegetation type, with thicket promoting travel on roads and the opposite being true of open woodland, however this was only true for females in groups of two or more. Main rivers represent high quality resource areas for lions in the reserve since they provide water, shelter, cover (hence ease of prey capture) and travel lines. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

The Australian sea lion, Neophoca cinerea, is Australia?s only endemic pinniped, and one of the rarest sea lions in the world. This species suffered localised extinction events, and a probable population decline during the commercial sealing era of the 18th to 20th centuries. This species also has a unique reproductive cycle and breeding system compared with all other pinnipeds. Unlike the usual annual, synchronous cycle, this species has a 17.5 month breeding cycle which is asynchronous across its range. Small groups of proximate colonies appear to breed synchronously, but otherwise the timing appears randomly distributed. It was proposed that this system is endogenously controlled and maintained by exclusive female natal site fidelity (Gales et al. 1994). This would have a discernible impact on the population genetic structure, and would be directly applicable to conservation management practices. Investigation of population genetic structure of the Australian sea lion using mtDNA and microsatellite markers revealed a highly subdivided population that showed strong patterns of sex-biased dispersal, and strong regional divisions. The level of female natal site fidelity was extreme, resulting in very high levels of genetic differentiation, unparalleled in other marine mammal populations. Significant divisions existed across both macro and micro geographic scales, with fixed differences occurring between colonies separated by as little as 20 kilometres. Strong phylogeographic patterning suggested that divisions between populations are of some antiquity. High levels of fixation in mtDNA markers among the many small colonies in Western Australia was attributed to the high rate of genetic drift in small populations, especially for these markers. Genetic subdivison, as measured by microsatellite markers, revealed a malebiased dispersal pattern. Levels of male dispersal were sufficient in overcoming the female natal site fidelity and rendering small groups of colonies effectively panmictic. However, the range of male dispersal was limited to approximately 200 kilometres and resulted in a regional population structure best defined by geographic distance. This level of subdivision was perhaps greater than expected given the dispersal capabilities of this species, and suggested that some behavioural processes may limit dispersal. Historical processes of extinction and colonisation are thought to have had a strong influence on the current pattern of population subdivision as well.

Vibrissae (whiskers) are important components of the mammalian tactile sensory system, and primarily function as detectors of environmental vibrotactile cues. Pinnipeds possess the largest and most highly innervated vibrissae among mammals and their vibrissae demonstrate a diversity of shapes and likely mechanical properties. These two characteristics are important for vibrotactile sensory perception. Vibrissae of most phocid seals exhibit a beaded morphology with repeated sequences of crests and troughs along their length. I comparatively characterized differences in vibrissae morphologies among phocid species with a beaded profile, phocid species with a smooth profile, and otariids with a smooth profile using traditional and geometric morphometric methods to test the hypothesis that vibrissal morphologies are species-specific manipulations of a common pattern. The traditional and geometric morphometric datasets were subsequently combined by mathematically scaling each to true rank, followed by a single eigendecomposition. Quadratic discriminant function analysis demonstrated that 79.3, 97.8 and 100% of individuals could be correctly classified to taxon based on vibrissal shape variables in the traditional, geometric and combined morphometric analyses, respectively. At least three separate morphologies were identified since phocids with beaded vibrissae, phocids with smooth vibrissae, and otariids each occupied distinct morphospace in the geometric morphometric and combined data analyses. Another important characteristic that influences the transduction of vibrotactile information to the mechanoreceptors in the follicle-sinus complex is the materials properties of the vibrissae. Vibrissae were modeled as cantilever beams and flexural stiffness (EI) was measured to test the hypotheses that the shape of beaded vibrissae reduces flexural stiffness and that vibrissae are anisotropic (orientations differ in EI). Species were significantly different and smooth vibrissae were generally stiffer than beaded vibrissae. Beaded vibrissae decrease vibrations in flow, which, combined with lower flexural stiffness values, may enhance detection of small changes in flow from swimming prey. The anterior plane of the vibrissae is likely the most biologically significant in tracking hydrodynamic trails but had lower flexural stiffness values than the dorsoventral orientation. There is likely a complex interaction between shape and mechanical properties in pinniped vibrissae but the ecological and functional implications are currently unknown.