We aimed to identify the volatile compounds in inflorescences of Rudbeckia hirta that may be responsible for the olfactory attraction of the crab spider Misumenoides formosipes to this plant. Our approach was to use ultrasonic extraction, separate the extract into fractions using flash chromatography with different solvent systems, and test the attraction of the male spiders to the pooled fractions using a y-tube olfactometer. Ultrasonic extraction is carried out using a mixture of 1:2 hexane/diethyl ether with 10 g of inflorescences for 30 minutes. Bioassay results indicated that male spiders chose the inflorescences, bulk ultrasonic extract, and the pooled 100% dichloromethane fractions over controls. Nuclear magnetic resonance experiments and infrared spectroscopy experiments were carried out on the 100% dichloromethane fractions and these experiments indicated that a long chain hydrocarbon is the main component in the 100% dichloromethane fractions / Chromatographic method and bioassay development method -- M. formosipes olfactory response to R. hirta -- Separation and identification of the possible attractants in the 100% dichloromethane fractions. / Department of Chemistry

An important issue in the area of biology is form following function. It is evident that animals have wide variation in morphology, but what functions do these forms follow? The postural stability of an animal decreases as the neural delay increases. This delay increases with animal size because signals must travel across a longer distance at a constant speed. Despite this increase in delay, large animals typically do not fall. In addition to the neural components, animal morphology also affects stability. Therefore it is possible that stability is a guiding principle of morphology. An animal may have a particular shape in order to function in its niche in an ecosystem while maintaining a stable morphology. It is proposed that in order to maintain postural stability, large animals have adapted different morphologies to counteract their longer neural delays. The postural stabilities of animals of different shapes and sizes will be examined using a mathematical model of balance. The effects of neural delay and morphology on postural stability were studied using a four-bar linkage model of frontal plane balance applied to previously- published morphological data from horses and dogs. The postural stability was quantified by calculating the maximum allowable neural delay for an animal in order for the animal to prevent falling via corrective action. This measure was compared to the calculated neural delay for each animal. It was found that maximum allowable delay scales proportionally to neural delay, indicating that postural stability may scale across animal size and morphology. The model has limitations in that it does not incorporate animal width into the calculation of neural delay, therefore excluding the effects of animal width. These results may reveal a scaling relationship for the stability of biological systems across sizes, morphologies, and species.

Previously, amphibian malformations had only been studied at the site, state and regional levels, limiting our understanding of the types of malformations most commonly occurring in wild populations across the country. This study presents the results of radiographic analyses performed on morphologically abnormal amphibians collected from National Wildlife Refuges in 27 states and 6 of 7 US Fish and Wildlife Service regions. Despite considerable differences in species composition and ecological factors (e.g., habitat type, climate and land use), it was observed that abnormalities were remarkably similar across regions of the country. One regional difference that was noted was that higher proportions of forelimb and craniofacial abnormalities were observed in the western regions (regions 1 and 7) compared to the eastern ones. However, the uneven distribution of these abnormalities across sites, suggest that these elevated proportions may not be characteristic of region 1. Differences in species composition as well as in ecological factors such as habitat type and climate are potential explanations for this pattern in region 7. Given the known differences in regional causes, the results of this study suggest that these stressors may be affecting amphibian development in the same manner to produce primarily hindlimb reductions. Continued research comparing the types of abnormalities produced in different areas of the country as well as what stressors are present is essential to identify cause and affect relationships at sites hosting abnormal amphibians. / Department of Biology

No description available.

Sauropod tooth morphologies and tooth replacement patterns bear important information on feeding habits and sauropod evolution. Euhelopus zdanskyi is an Early Cretaceous neosauropod, and belongs to the group Euhelopodidae, which is the sister group of Titanosauria. Euhelopus is a key taxon in the evolution of sauropod teeth, because it displays a very conservative tooth morphology compared to that seen in Titanosauria, despite being a close relative. The teeth of Euhelopus resemble those of Camarasaurus, as well as many basal sauropods that are not closely related to Euhelopus. The teeth of Euhelopus are spoon-shaped, and they have approximately two replacement teeth for each functional tooth. Their robust morphology and low number of replacement teeth suggest that they were worn down a lot more slowly than the pencil-shaped teeth of Titanosauria and Diplodocoidea. Diplodocoids, whose teeth have been studied widely, especially show very rapid tooth replacement rates, and the tooth morphology of titanosaurs suggests that they might have had similar replacement rates. On the contrary, Euhelopus was likely to have replacement rates similar to the relatively low rates of Camarasaurus, whose tooth battery is much like that of Euhelopus. Furthermore, some euhelopodids are known to have had pencil-shaped teeth, which indicates that there was a strong evolutionary pressure towards the development of narrow teeth during the Late Cretaceous. This pressure may have been caused by a change in vegetation or may merely represent somphospondylans occupying the niches vacated by the diplodocoids, which appear to have gone extinct before the end of the Cretaceous. This study uses 3D modelling for inspecting tooth replacement of Euhelopus and evolution of sauropod teeth.

This study resulted from the identification of gaps in the literature pertaining to the morphological descriptions of the tadpoles occurring at high altitudes in the Drakensberg Mountains in South Africa. These tadpoles are exposed to low temperatures, high desiccation risk, elevated ultraviolet radiation, competition, and predation and inhabit the clear, flowing streams and marsh areas of the mountain. Highly varying environmental conditions caused tadpoles to have considerable intraspecific variation. The high degree of plasticity necessitated extensive descriptive studies of tadpole morphology in order to document intraspecific variation and set up reliable keys for species identification. Specified adaptations to the extreme montane conditions are present in tadpoles of certain species. An especially interesting adaptation is the elygium, a hemispherical pigmented area above the eye, which apparently protects the retina from harmful ultraviolet radiation. There are no known studies of elygium plasticity in tadpole eyes in relation to variation in ultraviolet radiation. Particular attention was given to the functionality and cytology of this structure. Detailed measurements of tadpoles of six frog species of the high altitude Drakensberg Mountains were made. Morphological adaptations were described on the basis of these measurements. The cytological origin of the elygium of Amietia vertebralis was revealed through histological and cellular ultrastructure studies. The change in elygium morphology over time was studied as a function of ultraviolet intensity by exposing tadpoles to different levels of ultraviolet radiation. From the detailed morphological descriptions a more reliable binomial key was constructed, which made it possible to distinguish between Amietia umbraculata and A. vertebralis. A new amended definition of the epidermal elygium can now be given as an area of melanophores originating from the pigmented epithelium of the retina, forming a hemispherical shape from the dorsal margin of the iris. It is positioned in such a way as to protect the retina when light enters directly from above. This empirical study of the functional significance of the elygium showed that elygium morphology was considerably plastic, and that there were differences in elygium area and base length in the presence or absence of UVB radiation. In the presence of high UV radiation tadpoles produced an elygium with a broader base rather than longer elygia with a larger area. A wider elygium base shaded the pupil more effectively, thus protecting the retina from harmful UV radiation. The presence of a ventral elygium was also discovered. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Shippagan Gully is a highly dynamic tidal inlet located on the Gulf of St-Lawrence near Le Goulet, New Brunswick. This tidal inlet is highly unusual due to the fact that the inlet has two open boundaries with phase lagged tidal cycles that drives flow through the inlet. Over the past few decades, the shipping activities through the inlet have been threatened due to the narrowing of the navigation channel caused by deposited sediment on the east side of the channel. Many engineering projects have been undertaken at Shippagan Gully in order to try and mitigate the deposition problem. However, these attempts have either been unsuccessful or the engineered structures have deteriorated over the years. This study uses the CMS-Flow and CMS-Wave numerical models to provide guidance concerning the response of the inlet to various potential interventions aimed at improving navigation safety.

Gasterosteus aculeatus (threespine stickleback) is a well-known model for behavioral and evolutionary studies. Rapid evolutionary radiations in postglacial timeframes have promoted distinct local populations with remarkable variation in biological characteristics. This study examines genetic and morphological variation among populations from the Thlewiaza watershed, specifically an isolated freshwater population in Nueltin Lake. Statistically significant genetic differences were observed using 11 microsatellite loci; FST values ranged from 0.29 (within watershed) to 0.48 (between watersheds) in comparison with the Nueltin Lake population. Gene flow between populations was likely inhibited due to isostatic rebound following the recent deglaciation of North America, 8.5 kya. In comparison with similar freshwater populations, the retention of defensive structures in G. aculeatus from Nueltin Lake was unexpected, and may reflect strong piscivorous predation pressures. Levels of differentiation, both genetic and morphological, observed in the Nueltin Lake population are highly significant, and should be recognised as a Designatable Unit (DU).

This study resulted from the identification of gaps in the literature pertaining to the morphological descriptions of the tadpoles occurring at high altitudes in the Drakensberg Mountains in South Africa. These tadpoles are exposed to low temperatures, high desiccation risk, elevated ultraviolet radiation, competition, and predation and inhabit the clear, flowing streams and marsh areas of the mountain. Highly varying environmental conditions caused tadpoles to have considerable intraspecific variation. The high degree of plasticity necessitated extensive descriptive studies of tadpole morphology in order to document intraspecific variation and set up reliable keys for species identification. Specified adaptations to the extreme montane conditions are present in tadpoles of certain species. An especially interesting adaptation is the elygium, a hemispherical pigmented area above the eye, which apparently protects the retina from harmful ultraviolet radiation. There are no known studies of elygium plasticity in tadpole eyes in relation to variation in ultraviolet radiation. Particular attention was given to the functionality and cytology of this structure. Detailed measurements of tadpoles of six frog species of the high altitude Drakensberg Mountains were made. Morphological adaptations were described on the basis of these measurements. The cytological origin of the elygium of Amietia vertebralis was revealed through histological and cellular ultrastructure studies. The change in elygium morphology over time was studied as a function of ultraviolet intensity by exposing tadpoles to different levels of ultraviolet radiation. From the detailed morphological descriptions a more reliable binomial key was constructed, which made it possible to distinguish between Amietia umbraculata and A. vertebralis. A new amended definition of the epidermal elygium can now be given as an area of melanophores originating from the pigmented epithelium of the retina, forming a hemispherical shape from the dorsal margin of the iris. It is positioned in such a way as to protect the retina when light enters directly from above. This empirical study of the functional significance of the elygium showed that elygium morphology was considerably plastic, and that there were differences in elygium area and base length in the presence or absence of UVB radiation. In the presence of high UV radiation tadpoles produced an elygium with a broader base rather than longer elygia with a larger area. A wider elygium base shaded the pupil more effectively, thus protecting the retina from harmful UV radiation. The presence of a ventral elygium was also discovered. / Thesis (M.Sc. (Environmental Science))--North-West University, Potchefstroom Campus, 2011.

Increasing the taxonomic resolution of fossil pollen identification is important for accurate paleoecological reconstructions. Here, an attempt is made to identify the critical morphological features that will permit differentiation of Alnus pollen in fossil records. Palynologists working in the Pacific Northwest often distinguish alder pollen into two morphotypes. However, no definitive method outlining the validity of species level identifications has been devised to date. To test and validate species-level identifications, the pollen morphology of the three main alder species (Alnus viridis subsp. sinuata, Alnus incana subsp. tenuifolia and Alnus rubra) that occur in westernNorth America is examined with the goal of identifying morphological characteristics with which to distinguish the pollen of these species in fossil records. Modern pollen samples were collected from 27-35 individual plants from across the range of each of the three alder species. Pollen grains (n=30) from each individual plant were examined using light microscopy at 1000´ magnification under oil immersion. For each individual pollen grain, six quantitative traits (pollen grain diameter, exine thickness, arci width, and annulus height, width and area), and three qualitative traits (pore protrusion, grain shape and arci strength) were measured. In total, 21,390 alder pollen were examined from 93 separate collections. In addition, the number of pores was determined for 200 pollen grains from each individual plant. Statistically significant differences between species were found for all quantitative traits when traits were compared via nested ANOVA. However, there is high variability in pollen morphology within each species and pollen morphology is best described as occurring along a morphological continuum. A single morphological trait is insufficient for precise identification of alder pollen to species. CART analysis, when used to derive a multi-trait classification model, is shown to be a useful tool in separating the pollen of A. rubra and A. viridis subsp. sinuata into two separate ‘morphotypes,’ analogous to species identification. The confounding intermediate morphology of A. incana subsp. tenuifolia precludes the possibility of distinguishing the pollen of all three species. CART modelling isolates A. rubra and A. viridis subsp. sinuata pollen based on annulus width, arci strength, diameter and exine thickness, traits that support the differences used by palynologists for separating alder pollen into ‘morphotypes.’ Sensitivity analysis shows clearly that the common practice of using small sample sizes (e.g. n=7 and n=15) for identifying critical morphological traits for pollen identification produces misleading and erroneous results. Regional differences in pollen morphology were also assessed by splitting the dataset into regions. Classification accuracy is diminished from over 70% to less than 20% when a CART model derived from pollen grains from one region is used to classify grains from a different region. This research underscores the importance of using large sample sizes from across species’ ranges when attempting to determine the diagnostic morphological features for accurate pollen identification. / Graduate