This study examines the reproductive and population biology of a long-lived (80-y life span) fish, Sebastes alutus (Gilbert). The objectives of the study were (i) to establish whether groups of adult S. alutus delineated by exploitation histories could be objectively identified as separate sub-populations; (ii) to identify the effects of density-independent mortality caused by exploitation, and relate them to predictions of life history theory (iii) to examine the long-term implications of this mortality pressure on the dynamics of the species; and (iv) to determine the contribution of these results to the development of management programs for this species. A lernaepodid copepod gill parasite (Neobrachiella robusta (Wilson 1912)) was used for the first time as a biological tag to delineate separate sub-populations (stocks) of a commercial fish. Intensity of infection and mean characteristics of the parasite population per fish achieved complete separation between stocks indistinguishable with morphological features. Discriminant analysis showed the parasite also functioned moderately well (34-76% correct classification) as a stock discriminator of individual fish. Use of auxilliary information on the stock identity of hosts improved the classification power of the discriminant function. The density-independent mortality of the commercial fishery on S. alutus has severely truncated the age spectrum of some stocks. Some compensatory growth changes for fish in the stocks under the strongest selection are evident. Examination of the variance structure of female length at age suggests an inverse relation of mortality and growth rate giving rise to smaller, older fish. Smaller, older fish can be accounted for using the same growth function as for the larger fish seen at younger ages, and these similar growth forms can give an aggregate appearance of quadratic growth. Growth changes do not yield significant differences in size at maturity, although age at maturity changes, implying developmental or environmental constraints on maturation. Fecundity estimation methodology was evaluated and the volumetric method previously used for this species found to be inferior to a gravimetric method. Significant differences in fecundity as a function of body variables were found among exploitation groups. Significant differences in oocyte characteristics among stocks were found, with size and age shown to have separable effects. Lightly exploited stocks had significantly higher oocyte quality (as expressed in oocyte weight), effected through differences in the oocyte diameter-oocyte weight relationship. Histological examination details the developmental sequence of oocytes and establishes the maturation period of oocytes and fish. Northern stocks were shown to have significantly larger oocytes. Follicular atresia is suggested as an alternative energy source to the embryo death which has been presented as the source for matrotrophy in this genus. Complete atresia of a ripe oocyte complement was identified in this genus for the first time. No evidence of reproductive senescence was found. The hypothesis of increasing reproductive effort with age, including the independence of age and size effects, was confirmed. No evidence of reproductive cost could be found. The hypothesis of increased reproductive effort earlier in life as a mechanism to offset increased adult mortality was supported. However, the potential of this increase, achieved by growth rate increases, is much less than is needed to compensate for the reduction in lifetime reproductive effort caused by high fishing mortality. The effects of changing mortality rates on several reproductive value indices was examined with deterministic and stochastic simulation models. Cohort reproductive value is the most sensitive of the indices examined and may be the most robust to measurement error. Reproductive value is a more sensitive index of population state than other indices in use and may play a role in determination and evaluation of optimal harvest policies. However, an experimental approach to its use will be required. / Science, Faculty of / Zoology, Department of / Graduate

Four experiments were conducted in an effort to explain further the genetics and physiology of sexual behavior in chickens and Japanese quail. The populations used in this research included lines that had undergone over 20 generations of divergent selection for high and low mating frequency and the random bred control population from which the selected lines originated. In the first experiment, fertility comparisons under natural and artificial mating situations were made over time among male chickens from the selected and control lines. Although there were highly significant differences among the lines for mating frequency, total fertility was similar among lines when mating was by either natural or artificial means. Significantly more days were needed to reach peak fertility when mating was by natural rather than artificial means. This difference may be attributed to male-female interactions whereby all females in a flock would not be fertilized on the same day in natural mating situations. This same reasoning could explain the significant differences noted between mating situations for duration of fertility. The second experiment examined the mode of inheritance of mating behavior and testosterone levels in chickens using the selected lines plus reciprocal crosses among these lines. No differences among mating combinations were found for circulating testosterone levels. In all cases, androgen titers appeared to be of a sufficient magnitude to influence mating behavior. Heterotic effects were found for mating behaviors in cross-pureline comparisons suggesting that nonadditive genetic variation influences the thresholds for mating in the fowl. Electroencephalographic effects of mating behavior of the selected lines were studied in the third experiment. There was an inverse relationship between number of peaks and voltages per peak, with differences in the number of peaks being significant among lines, implant locations and behavioral situations. Highly significant differences were found among lines for all voltage measurements with the control line having the highest voltage and the low mating line having the lowest voltage. These observations were discussed in the context of their effects on inhibitory and stimulatory mating centers. The genetics of mating frequency in male Japanese quail was studied in the fourth experiment utilizing replicated lines selected for high or low mating frequency and the randombred control line that served as the base population for the selected lines. Comparisons involved the purelines, F₁, F₂ and backcross generation progeny. The results indicate that the primary heritable variation for mating frequency in this species is primarily additive. Correlated responses of cloacal gland size and relative aggressiveness to selection for mating frequency are discussed in the context of alterations in physiological and behavioral responses. / Ph. D.

No description available.

Amphibian populations worldwide are currently in decline. One approach to preventing extinction of some of the affected species is to create assurance colonies. These sustainable captive populations might some day be used to reestablish wild populations. One issue with creating assurance colonies is successful breeding; often difficulties arise when attempting to breed exotic animals in captivity. Sexual conditioning, a form of Pavlovian conditioning, has been shown to improve breeding behavior. In this project the efficacy of sexual conditioning to improve breeding behavior in the dyeing dart frog (Dendrobates tinctorius) was tested. The frogs were trained with a stimulus that was either predictive of or independent of exposure to a member of the opposite sex. The group trained with the predictive stimulus showed shorter latencies to a variety of breeding behaviors and produced more eggs than the control groups. The sexual conditioning procedure also increased expression of various breeding behaviors allowing for careful examination of calls and visual signaling within this species.

In this thesis, I analysed the mating behaviour of the solitary-nesting American kestrel (Falco sparverius) in southern Quebec (Canada) and the colony-nesting lesser kestrel (F. naumanni) in Aragon (Spain). DNA fingerprinting of 26 families of lesser kestrels revealed that 3.4% of nestlings were extra-pair, which may have arisen through either extra-pair copulation or mate replacement. Two nestlings in two different nests were also the result of intraspecific brood parasitism. DNA fingerprinting of 21 American kestrel families showed that all the nestlings in two nests were extra-pair (10% extra-pair young overall), most probably due to mate replacement. / I analysed the mating behaviour of both species in two studies with a similar aim, i.e. to test why mated pairs copulate so frequently. Sixteen pairs of wild American kestrels and 12 pairs of "solitary" lesser kestrels (14 nests per 0.3 km$ sp2)$ were analysed in terms of four hypotheses that explain high frequency of within-pair copulations both outside and during the fertile period. First the Paternity Assurance Hypothesis, i.e. males control timing and frequency of copulations to best assure fertilization, was rejected because extra-pair copulation attempts were low in both species ($<$1% of all copulations observed), within-pair copulation frequencies did not increase with nest density in the lesser kestrel, and copulation and mate attendance did not increase as the fertile period approached. Second, the Immediate Material Benefits Hypothesis, i.e. females trade copulations for food, was refuted because copulation most often occurred without food transfers. Third, the Female Mate-Guarding of Males Hypothesis, i.e. females distract their mates from other mating opportunities by copulating frequently, was rejected because male loss was low, males and females solicited similar amounts of copulations, and females did not differ in the timing or frequency of solicitations. Finally, the Mate Assessment Hypothesis, i.e. assessment of mate quality is mediated by copulation, most closely predicted the behaviour observed since within-pair copulation was high outside the fertile period and during pair formation in both species.

Orientador: Eleonore Zulnara Freire Setz / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-04T03:03:59Z (GMT). No. of bitstreams: 1 Jardim_MarciaMariadeAssis_D.pdf: 906770 bytes, checksum: 81b5c547024efb307fcafd7bdc02a344 (MD5) Previous issue date: 2005 / Resumo: Parâmetros populacionais são importantes indicadores de como as populações estão superando condições desfavoráveis e quais as suas perspectivas de sobrevivência a longo prazo. No período de dezembro de 1999 a dezembro de 2001, nós acompanhamos bimestralmente 10 grupos de bugios ruivos (Alouatta guariba clamitans) residentes em três fragmentos florestais nos municípios de Porto Alegre e Viamão, RS. Foram realizadas 13 expedições nas quais foram registrados os seguintes dados: data, horário, local e composição social de cada grupo. O intervalo médio entre os monitoramentos foi de 50,2 dias, totalizando 149 dias de campo e 219 encontros com grupos de bugios. O tamanho médio dos grupos foi de 8,2 indivíduos, sendo 1,3 machos adultos; 2,6 fêmeas adultas; 0,3 machos subadultos; 0,8 juvenis II; 2,3 juvenis I; 0,6 infantes II e 0,4 infantes I. Todos os grupos apresentaram alterações na composição social ao longo dos dois anos. Foram registrados 31 nascimentos, sendo a taxa anual de natalidade de 0,6 por fêmea adulta. O intervalo médio entre os nascimentos foi estimado em 14,7 meses. No decorrer do período, foram observados 16 casos de desaparecimentos (emigrações e/ou mortes) e uma imigração de uma fêmea adulta. Para enriquecimento da análise foram considerados mais cinco casos de desaparecimentos ocorridos em 1999 nos grupos de estudo, observados no período piloto e através de relatos de outros pesquisadores. Ao longo dos dois anos de monitoramento, o tamanho médio de área de vida estimado para os dez grupos foi de 4,4 ha pelo método do polígono mínimo convexo e 4,2 ha pelo método de esquadrinhamento (25x25m). A área de uso individual variou entre 0,2 a 1,1; com média de 0,5 ha por indivíduo. A sobreposição de áreas de uso variou de 0 a 39%. A densidade populacional e o tamanho de fragmentos foram os fatores mais determinantes no tamanho da área de uso e parecem ser melhores previsores para a espécie como um todo. Os resultados demonstraram um tamanho de grupo médio superior ao encontrado na literatura, altas taxas reprodutivas e variações relevantes na composição social dos grupos, indicando uma situação de crescimento populacional e dinâmica dos grupos intensa. A sobrevivência destas populações a longo prazo, no entanto, é incerta, devido à alta pressão de ocupação urbana e conseqüente fragmentação do hábitat, dificultando a dispersão efetiva dos indivíduos e aumentando as chances de depressão por endocruzamento / Abstract: Population parameters are important indicators of how populations are overcoming unfavourable conditions and of their perspectives of long term survival. Ten groups of brown howler monkeys (Alouatta guariba clamitans) living in three forest fragments around the cities of Porto Alegre and Viamão, RS, were followed bimonthly from December 1999 to December 2001. Thirteen expeditions were carried out and the following information was registered: date, time, location, and social composition of each group. The average interval between the expeditions was 50.2 days, with a total of 142 days on site and 214 encounters with groups of howler monkeys. The groups had an average size of 8.2 individuals, 1.3 adult males; 2.6 adult females; 0.3 subadult males; 0.8 juveniles II; 2.3 juveniles I; 0.6 infants II and 0.4 infants I. All groups presented alterations in social composition during the two-year period. Thirty-one births were registered, with an annual birth rate of 0.6 per adult female. The average interval between births was estimated in 14.7 months. Sixteen disappearances cases (emigrations and/or deaths) and the immigration of one adult female were observed during this period. Five additional disappearances cases within the study groups were considered in order to enhance the analysis. They all occurred in 1999 and were observed during the pilot period or reported by other researchers. The estimated average home range of all ten groups during the two-year monitoring was 4.4 ha using the minimum convex polygon method, and 4.2 ha using the grid method (25x25m). The area of individual use varied between 0.2 and 1.1, with an average of 0.5 ha per individual. The overlap of home range varied between 0 and 39%. Population density and size of fragments were the most important factors determining the size of use area and seem to be better predictors for the species as a whole. The results demonstrated an average group size superior to that found in literature, high reproductive rates and relevant variations in the social composition of groups, indicating population increase and intense group dynamics. However, the long term survival of these populations is uncertain due to the high pressure of urban occupation and the consequent fragmentation of their habitat, making the effective dispersal of individuals more difficult, and increasing the chances of depression by inbreeding / Doutorado / Ecologia / Doutor em Ecologia

The Asian elephant (Elephas maximus), a charismatic ‘flagship species’, is threatened by extinction in the wild, and the development of self-sustainable captive populations is a key conservation challenge. A third of the Asian elephant population is presently in captivity and information on the reproductive status, especially in females, is still lacking to a large extent. The onset of estrus in female Asian elephants is not associated with any visible physical signs, thus making the assessment of the reproductive status rather difficult. One approach to understanding reproductive cyclicity of animals is through generating profiles of reproductive hormones in blood (Wiseman et al. 1983; Brown et al. 1999, 2004). Profiles of reproductive hormones such as progesterone (P4), estrogen, luteinizing hormone and follicle stimulating hormone have already being demonstrated in Asian elephants (Brown et al. 1999, 2004; Brown 2000). In these studies, the reproductive status of females, maintained in zoos/captivity, was characterized based on circulating levels of hormones in blood samples. This is difficult to implement in the case of semi-captive or wild populations of elephants due to practical, legal and ethical considerations. In order to overcome this problem and to better understand the estrous status of female elephants, it is important to develop and validate non-invasive methods to monitor the reproductive status of female Asian elephants. An alternative approach to evaluating the reproductive status of females is to consider behavioral responses shown by males towards chemical signals produced by females to advertise their reproductive status. In order to understand the reproductive status of the individual belonging to the opposite sex, studies have shown that elephants rely on a variety of chemical signals produced in biological fluids such as urine, temporal gland secretion, inter-digital gland secretion, etc. (Krishnan 1972; Rasmussen & Schulte 1998). Chemical signaling is one of the prominent modes of communication in elephants, especially with respect to locating potential mates (Sukumar 2003). Thus, in most cases, elephants usually employ specific behavioral responses, for example sniff, check and place behaviors of trunk, for investigating the reproductive status of the conspecific individual, belonging either to the same or the opposite sex (Rasmussen et al. 1996; Schulte & Rasmussen 1999; Bagley et al. 2006). The objectives of the thesis are two-fold. First, to develop a non-invasive method of reproductive monitoring from fecal hormonal metabolites and also to understand the possible role of feces as an inter-sexual signal. The main body of thesis is divided into four chapters. 1) Development and validation of a non-invasive method to estimate progesterone metabolite in feces, to monitor the reproductive cyclicity of female elephants (Chapter 2). 2)Generation and characterization of progesterone and its metabolite, 5α-P-3-OH, profiles of semi-captive females using the developed non-invasive method to measure fecal metabolites (Chapter 3). 3) Validation of developed methodology and assay systems to a wild-population of female elephants (Chapter 4). 4) Feces as a potential source for inter-sexual chemical signaling in Asian elephants (Chapter 5). The above studies were carried out on semi-captive male and female elephants maintained in the forest camps of Mudumalai Wildlife Sanctuary (MWLS), Tamil Nadu and Bandipur National Park (BNP), Karnataka, India (Chapters 2, 3 and 5). For Chapter-4, free-ranging females of the MWLS were examined. 1. Development and validation of a non-invasive method to estimate progesterone metabolite in feces, to monitor the reproductive cyclicity of female elephants Niemuller et al. (1993) generated a profile of the progesterone metabolite, 5βpregnanetriol, to assess the estrous phase of Asian elephants based on non-invasive urine sampling. However, the collection of urine is difficult and to some extent impossible in the case of semi-captive and as well as that of wild elephants. Thus, the method of choice in this study was the development and validation of a non-invasive approach to measure fecal progesterone metabolites to assess reproductive status of females. Sampling was carried out at monthly intervals on three female elephants at the MWLS forest camp, while three other females maintained at the BNP forest camp were sampled fortnightly. An enzyme linked immuno-sorbent assay was developed to measure the concentration of the progesterone metabolite, 5α-P-3OH in the fecal samples of the semi-captive females. Using varying concentrations of the hapten (5α-P3OH), from low (0.1 mM) to high (1 mM), a standard curve was first generated, which had a linear range between 0.25 mM to 62.5 mM, with an EC50 of 1.37 mM. The linear range was then used to detect the concentrations of 5α-P-3OH in the fecal samples of females examined. The non-invasive method was further validated as there existed a positive correlation (p<0.1) between the levels of fecal 5α-P-3OH and that of concentration of circulating P4, measured in blood samples. This is the first valid documentation of a non-invasive method based on fecal progesterone metabolite pattern in order to assess the reproductive status of the female Asian elephants. 2. Generation and characterization of reproductive hormone profiles of semi-captive females using the developed non-invasive method to measure fecal metabolites With the establishment of a non-invasive method to understand occurrence of estrus in female elephants (described in Chapter 2), attempts were made to generate hormonal profiles over a longer time interval through more frequent sampling. Based on sampling at weekly intervals, the concentrations of both fecal 5α-P-3OH and that of native P4 hormone in the blood were determined, and the females were then identified as belonging to different reproductive states of hormonal cycling (follicular and luteal phases), non-cycling and pregnant categories. Of the 7 females sampled at both MWLS and BNP, three distinct categories of hormone-metabolite profiles emerged. The first category included four females that showed regular cyclicity throughout the sampling period, as monitored through the measurement of fecal 5α-P-3OH and serum P4 levels. The estrous cycle of all the four females was divided into two phases (follicular and luteal), based on the patterns of fecal 5α-P-3OH and serum P4 concentrations. The follicular phase of the estrous cycle was assigned when the values of both fecal 5α-P-3OH and serum P4 remained below 0.3 µg/gm and 0.3 ng/ml, respectively, for a considerable time period (viz. >2 wk). However, the luteal phase was characterized, when the levels of fecal 5α-P-3OH and serum P4 remained at or above 0.3 µg/gm and 0.3 ng/ml respectively, over a period of more than 2 - 3 wk. The second category had two females showing a ‘flat-lining pattern’ for the levels of fecal 5α-P-3OH and serum P4 concentrations, without any peak or dip in their concentrations. Since the reproductive pattern for both these females was flat-lined throughout their sampling period (51 wk), maintaining the levels of fecal 5α-P-3OH and serum P4 below 0.3 µg/gm and 0.3 ng/ml respectively, the females were considered to be non-cycling or anestrus. The third category had one female in which the levels of both fecal 5α-P-3OH and serum P4 measured were consistently high throughout the entire sampling period (26 wk). The levels of both fecal -P-3OH and serum P4 were above 0.3 µg/gm and 0.3 ng/ml, respectively. At the end of the sampling period, this female delivered a male calf; thus, the measured concentrations of fecal 5α-P-3OH and serum P4 signified the levels maintained during the gestational phase of this female. Sampling and hormonal analyses were also carried out for a male in the MWLS forest camps to investigate the baseline concentrations of fecal 5α-P-3OH and serum P4. The male showed consistently low concentrations of both fecal 5α-P-3OH and serum P4 throughout the sampling period (16 wk), below the margin of 0.3 µg/gm and 0.3 ng/ml, respectively. In this part of the study, it was confirmed that the reproductive status of a female elephant can be correctly assessed on the basis of measurements of fecal 5α-P-3OH alone, with repeated sampling of the female over a longer time scale. It was also shown that the strength of the positive correlation between the concentrations of the fecal 5α-P3OH and the serum P4 increased (p<0.01) for a larger sample size than that obtained for a comparatively smaller sample (described in Chapter 2). 3. Validation of developed methodology and assay systems to wild-population of female elephants So far, the non-invasive method to estimate fecal progesterone metabolite in order to predict occurrence of estrus of elephants was largely applied to semi-captive females (described in Chapters 2, 3). However, the necessity of such a method is being recognized for assessing the reproductive status of free-ranging females. Several findings have described differences in the rate and type of steroid metabolite excretion among individuals maintained under different diet regimes (Wasser et al. 1993; Smith et al. 2006). For instance, female elephants in the forest camps are provided with supplementary diet consisting of sugarcane, rice and millets. This diet is strikingly different from the feeding materials consumed by wild/free-ranging elephants (Sukumar 2003). Therefore, differences in dietary components can potentially influence the fecal steroid metabolites’ excretory patterns shown by semi-captive vis-a-vis wild females, which can affect the validity of measuring fecal 5α-P-3OH to predict females’ reproductive status. In order to examine this problem, the non-invasive method was applied to the population of wild elephants in the forests of MWLS, through random one time sampling of 30 individual female elephants. The steroid extraction efficiency (73 ± 11.0%, mean ± S.D., n =30) determined for the fecal samples collected from the wild females was not significantly different from the coefficient calculated in the case of the semi-captive females (80 ± 4.3%, mean ± S.D., n = 38). This indicated that dietary differences between wild and captive elephants did not influence levels of fecal hormonal metabolites in feces, unlike earlier observations on baboons (Wasser et al. 1993), old world primates (Wasser et al. 1988) and sheep (Smith et al. 2006). The values of the fecal allopregnanolone determined in the case of the wild females, ranged from as low as 0.06 µg/gm to as high as 23µg/gm of the sample, thus showing the heterogeneity of the samples, indicating that the females may be belonging to different reproductive phases. However, since sampling was carried out randomly, with an adult female being sampled just once, at this stage, it is not possible to identify or elaborate on the reproductive phase of the females. This is the first study reporting the values of the fecal progesterone metabolite in female Asian elephants in the wild. Further studies may be required to carry out long term monitoring of the wild females, through repeated collection of fecal samples over time from particular female. 4. Feces as a potential source for inter-sexual chemical signaling in Asian elephants In this Chapter-5, behavioral trials were conducted on male elephants to understand the role of fecal matter in conveying inter-sexual chemical signals. This was demonstrated by analyses of specific chemosensory behavioral responses shown by males towards the fecal samples of females that were strangers and belonging to different reproductive stages. Males showed four prominent behavioral responses namely ‘distant sniff’, ‘close sniff’, ‘check’ and ‘place’ towards the fecal samples of females. The sum of frequencies of these four responses (distant sniff, close sniff, check and place) was much higher for samples of the follicular (pre-ovulatory) phase females as compared to those of the luteal (post-ovulatory) phase females (p<0.005). Thus, for the first time, it was shown that male elephants are able to discriminate the different reproductive phases of females based on their specific behavioral response towards the fecal samples of the opposite sex. In conclusion, the thesis has focused on understanding and providing new insights regarding the reproductive biology of the female Asian elephants. This has been achieved through the development of the non-invasive method based on measuring the concentrations of the fecal progesterone metabolite and through the analyses of the chemosensory responses performed by the males towards the fecal samples of strange females. These methods can potentially be applied to the populations of both wild and captive/semi-captive female elephants in order to evaluate their reproductive status, through non-invasive measures. The information derived from the application of such methods will help in understanding the reproductive potential of the wild elephants under various environmental and ecological conditions. Further, the non-invasive measurement of reproductive hormones will help in monitoring the reproductive state of the individuals and thus aid in planning strategies for the welfare and management of the elephants maintained in captive or semi-captive conditions.

Sexually selected ornaments are among the most spectacular traits in nature. Indeed, the extreme costs associated with producing sexual traits seem to play a crucial role in their evolution by enforcing honest levels of advertisement: only males with high levels of acquired resources (or high ‘condition’, as it is known in the literature) can afford to produce extravagant signals, a phenomenon which maintains signal reliability in a constant environment. In my thesis I examine many implications of this condition-dependent model of ornament and preference evolution for variation in age-dependent allocation to sexual signals and other life history traits. In Chapter 1, I review theoretical implications of condition-dependent signalling for life history and sexual selection theory. I note that a universal cost of expenditure in sexual advertisement is metabolic in nature: metabolites used to fund ornament expression are by definition unavailable to other life history traits that compete for a limited resource pool. This universal constraint on expenditure does more than maintain honesty (as noted above), however: the reliance of sexual displays on high levels of nutrient acquisition may help maintain genetic variation in sexual signals that would otherwise be eroded by strong mate choice, and without which the selective basis for good-genes choice would disappear. Three mechanisms in particular probably help to maintain genetic variation in acquisition. 1) Because acquiring resources and converting them efficiently to useful forms depends on the high function of many biochemical pathways, condition is undoubtedly highly polygenic, which slows the erosion of genetic variation under strong directional selection by females (especially in the presence of epistatic interactions). 2) The highly polygenic nature of condition also presents a large target for mutation, which continually restores variation at the loci under selection. 3) The many loci underlying condition may also be particularly sensitive to environmental heterogeneity in time or space. By favouring the most ornate males, females acquire high performing genes for their offspring, regardless of the precise allele combinations that have conferred the ability to acquire resources. Selection on specific alleles is liable to fluctuate over time or space whenever allelic performance is strongly context-specific. I close by noting the considerable challenges in advancing research on sexual selection and life history allocation, including the fact that two key processes central to life history (acquisition and allocation) are latent variables that interact in complexways and are intrinsically difficult to measure empirically. In the remainder of my thesis I conduct a series of experiments involving decorated crickets, Gryllodes sigillatus, which are useful models for studying life history because they enable precise measurement of male reproductive effort. Male G. sigillatus face important allocation decisions owing to the highly polyandrous nature of females, and the substantial costs involved in signalling and mating. Chapter 2 examines sex differences in age-dependent reproductive effort as a function of diet and development stage. I reared outbred crickets using four combinations of diet nutritional quality, and studied the effects of these combinations on male and female reproductive effort (calling effort in males and fecundity in females) and longevity. While I expected males to be more sensitive than females to variation in diet and developmental changes in its quality, I actually observed the opposite: males in all treatments increased calling effort over time, exhibiting consistently positive covariance between calling effort and longevity across treatments. By contrast, the relationships between female reproductive effort and longevity changed dramatically across treatments, and females who lived to intermediate ages had the highest fecundity. Although my results support sex-specific selection on life history allocation over time, a compelling additional explanation for my findings relates to the strategic role of calling for achieving male fitness. In the absence of positive feedback from potential mates, perhaps male allocation to sexual advertisement is careful and only increases gradually as a function of accumulating metabolic resources and increasing risk of intrinsic mortality. Alleles underlying condition are expected to be particularly sensitive to environmental heterogeneity. While this sensitivity may help maintain additive variation in male quality (which is essential for the sustenance of adaptive good-genes mate choice, as noted in Chapter 1), too much environmental sensitivity could also underiii mine the signal value of the male trait. For example, if there are strong genotypeby- environment interactions (GEIs) for sexual advertisement, in a rapidly changing environment females risk favouring a male whose alleles are no longer best suited to current conditions. This problem is particularly pressing for animals like crickets where males exhibit a behaviourally plastic sexual display (such as calling), and so may dynamically adjust signalling effort over time. In Chapter 3, I used inbred lines of decorated crickets to quantify age and diet dependent genetic variation in male signalling. I demonstrate that while genetic correlations across diets were quite strong for morphological traits, correlations between measures of the male sexual trait rapidly approached zero as I increased the distance in time (i.e., across widely spaced ages) or diet (i.e., comparing more dissimilar dietary histories) between samples. While extrapolating from my laboratory experiments to nature is difficult, my findings nevertheless cast doubt on the value of behaviourally dynamic signals (such as cricket calls) for reliably indicating genetic quality in realistically complex environments. In Chapter 4 I used physiological assays to evaluate factors affecting metabolite storage and use over time in decorated crickets. I manipulated the acquisition ability of all males using artificial diets that varied linearly in nutrient quality, and manipulated access to female mates over the course of the second week of adult life. By sacrificing crickets at key stages before and after manipulating the diet and social environment, I was able to estimate changes in stored metabolites, and relate these changes to calling effort and longevity. During the first week of adulthood (in the absence of females), higher diet quality significantly increased calling effort and storage of lipid, glycogen, and carbohydrate (but not protein). The presence of females increased both the probability of calling and the amount of calling during the second week, whereas diet quality only improved calling effort. By the end of the second week, calling effort had decreased, even by high quality males in the presence of females, suggesting a depletion of resources. Furthermore, the loss of condition during week 2 covaried with calling effort during the previous week irrespective of diet. Males who started the second week in high condition lost more glycogen and carbohydrate than rivals; meanwhile, lipid accumulation covaried positively with calling effort during week 2. The contrasting patterns of storage and use for lipids compared to the ‘quick-release’ metabolites (glycogen and carbohydrates) affirms starkly distinct functions for the different storage components, and underlines the importance of specific physiological measures in life history research. Finally, in the general discussion, I attempt to synthesise my thesis’s contributions to the study of life history trade-offs involving behavioural sexual displays.

Parmi les modes de communication les plus exploités chez les insectes, la communication chimique figure en bonne place. D’ailleurs, la recherche moderne consacrée aux signaux chimiques émis et perçus par les individus d’une même espèce n’a de cesse de se développer depuis plus de 50 ans. A travers ce travail de thèse, nous nous sommes intéressés à ces phéromones associées au comportement sexuel de Gastrophysa viridula (Coleoptera :Chrysomelidae). Nous avons menés, dans ce cadre, plusieurs bioessais comportementaux liés pour la plupart à des analyses chimiques par chromatographie gazeuse couplée à une spectrométrie de masse (GC-MS).<p>La fonction la plus évidente de la phéromone sexuelle de G. viridula est l’induction du comportement sexuel mâle. Cet « aphrodisiaque », probablement constitué de plusieurs composés cuticulaires (des alcanes méthylés lourds), est émis par la femelle et déclenche par contact la sortie de l’édéage des mâles. Etonnamment, ces composés se retrouvent aussi chez les mâles de G. viridula dont le comportement sexuel est alors induit au contact de composés cuticulaires mâles. Ceci constituerait la cause proximale des comportements homosexuels observés chez les mâles de G. viridula. Nous avons ensuite étudié le rôle des composés cuticulaires dans l’isolement sexuel entre G. viridula et G. cyanea. Le comportement sexuel des mâles des deux espèces est en effet induit préférentiellement par les femelles conspécifiques. Pour G. viridula, cette préférence est visiblement attribuable aux composés cuticulaires. Enfin, les signaux chimiques sont parfois indicateurs du degré de compétition spermatique rencontré par un mâle et permettent à celui-ci d’ajuster la quantité de spermatozoïdes transmis à une femelle. Avant d’étudier l’implication de tels signaux chez G. viridula, nous avons souhaité mettre en évidence un ajustement de la quantité de spermatozoïdes transmis par des mâles soumis à divers degrés de compétition spermatique. Nos résultats ne nous permettent malheureusement pas de signaler un tel effet.<p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Thesis (M.A. Agricultural Management (Animal Production)) -- University of Limpopo, 2020 / The Nguni is indigenous multi-purpose cattle breed that plays an important role in both commercial and communal farming systems in South Africa (SA). Unfortunately, the breed is currently under threat of diminishing due to farmers’ preference for exotic breeds and cross breeding. In recognition of the above, the Industrial Development Corporation, the Mpumalanga Department of Agriculture, Rural Development, Land and Environmental Affairs and the University of Limpopo established the Nguni cattle breed preservation project. In this project, a herd of 30 Nguni heifers and 1 bull were allocated to 34 Communal Property Associations (CPA) and 40 private farming enterprises each. With its three distinct ecological zones (High, Mid and Low-veld), the Mpumalanga province poses a challenge to the Nguni preservation project since cattle have to adapt to different ecological zones in order to grow and reproduce efficiently. Knowledge of cattle herd productivity improves the understanding of the functional attributes and is useful in determining the constraints and the potential of communal beef cattle production systems. Significant differences between ecological zones were observed for age at first calving, weaning rate, calves’ birth weight and calves’ weaning weight (p < 0.05). Calving of heifers in the Mid-veld zone occurred earlier (24 months) on both ownership types compared to Highveld (28.09 months for private and 26.00 for CPA) and the Lowveld (28.35 months for both ownerships). Nguni cattle on the Highveld performed better in terms of weaning rate under both private and CPA ownerships, where the weaning rate were 93% and 80%, respectively. Calves birth weight was lower in both ownership types in the Midveld zone (22.17 kg), whereas in the CPA, the Lowveld zone had higher calves birth weights (26.80 kg). In the private ownership, the highest calves’ birth weight (25.35 kg) was on the Highveld. The calves weaning weight were significantly higher (p < 0.05) on Highveld in private ownership (190.16 kg) and lowest (160.39 kg) in the Midveld zone. For the CPA, the highest calves weaning weight was also on the Highveld (187.55) and lowest on Midveld (167.50 kg). A full range of backup services that are offered to the communities by stakeholders in the form of a beef package that includes veld and pasture management, nutrition management, beef performance, animal recording keeping, genetic evaluation and animal health management program needs thorough attention.