Parasites have detrimental effects on an animal's fitness and could play a significant role in shaping the adaptive behaviour of animals. Natural selection may favour those behaviours utilised by animals that minimise the risk and intensity of infections. Animals use a range of behavioural strategies associated with grooming, social, mating, migratory and foraging behaviours to minimise their parasite burdens. Herbivores have two means available for reducing the effects of parasites while foraging. They may avoid parasites or consume plants with anti-parasitic properties. Sheep (Ovis aries) were shown to avoid foraging in areas of the sward contaminated with O. circumcincta infective larvae but could only do so when larvae were associated with faeces. The ability of sheep to avoid contaminated patches of the sward increased as the size of contaminated sward patches increased. This avoidance behaviour resulted in a reduction in the numbers of parasites ingested. Animals infected with O. circumcincta were more selective in their grazing behaviour than uninfected animals with respect to faeces avoidance. In order to determine which plants possess anti-parasitic properties Lotus pedunculatus, Pinus sylvestris, Tanacetum vulgare and Artemisia absinthium extracts were screened against Trichostrongylus colubriformis infections in the Mongolian gerbil (Meriones unguiculatus). Only A. absinthium merited further investigation as it appeared to suppress worm burdens when administered in a high single dose. A. absinthium extracts were subsequently administered to sheep infected with T. colubriformis.

Thesis (Ph. D.)--University of Chicago, Committee on Evolutionary Biology, 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Queensland, 2003. / Includes bibliographical references.

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 250-260).

No description available.

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<p>The concept of biological fitness is foundational for our understanding of both ecology and evolution. Fitness is often described vaguely as an organism’s contribution to the next generation. The reason this is vague is because researchers define and measure fitness differently across fields. I suggest that the myriad definitions and ways to measure fitness commonly employed have led to debates and, seemingly contradictory results. In order to investigate the use of the concept of fitness, I performed a literature review and asked, (1) How is biological fitness defined and used by researchers? (2) How is fitness actually measured by researchers? To address these questions, I surveyed 478 papers published between 2012 and 2016, that included the word ‘fitness’ in the title, and were in the Web of Science categories of ‘ecology’ and ‘evolutionary biology’. In my analysis of the journal articles fitness was only defined 33% of the time. Among studies that did explicitly define fitness, I categorized 18 different definitions, though only 7 were found in more than 5% of papers. I also found differences in how fitness was measured. I found 87 measurements that I grouped into 13 categories. In addition to my survey of the literature, I performed an experiment to explore the relationship between different measures of fitness. Vegetative biomass and reproductive biomass are often both used as metrics of fitness by plant ecologists. In this experiment I determined the relationship between two popular measures of plant fitness vegetative biomass and reproductive yield. I found that these two proxies for plant fitness, vegetative biomass and reproduction, were unimodally related, meaning: 1) intermediate sized plants have the greatest reproductive output, and; 2) for any unique amount of reproduction there is both a small and a large plant with identical reproductive output. Two things emerge from the literature review and the experiment: first, given the many definitions that exist, researchers should be clear about which one they are using. Second, one must be clear about the expected relationship between proxy measurements and fitness, as it may be complex, or non-existent.</p><p></p>

This study examined what effects, if any, cultural factors have on conceptual knowledge of evolutionary theory through natural selection. In particular, the study determines if Latino and non-Latino students differ in their misconceptions of natural selection and, if so, whether or not cultural factors could be the reason why such differences exist. A total of 1179 college students attending eight Hispanic-Serving Institutions in Texas participated in the study. The results revealed that the top two challenging natural selection concepts for students to comprehend were causes of phenotypic variation, i.e., mutations are intentional, and selective survival based on heritable traits. In addition, no statistical significant differences were found between the Latino and non-Latino students and the top four natural selection misconceptions between the groups were similar. Not even religion was found to directly contribute to evolutionary misconceptions; even though, it serves as the core of an individual’s beliefs system. However, traditional teaching methods, inadequately trained biology school teachers, lessons poor in content, insufficient teaching time, and lack of age appropriate tasks, as well as, poorly defined evolutionary terms are actually the main causes for evolutionary misconceptions.

Thesis (Ph. D.)--University of Chicago, Committee of Genetics, 2002. / Includes bibliographical references. Also available on the Internet.