It is now well accepted, through the use of mutational studies, that genes influence behavioural variation. However, we have little knowledge of the cellular and neuronal mechanisms underlying the effects of specific genes. This thesis broadens our understanding of the neurogenetic underpinnings of naturally occurring differences in behaviour using the genetically tractable model organism Drosophila melanogaster. The thesis focuses on allelic variation at the foraging (for) gene which influences both larval and adult behaviour. In particular, for’s cellular/neural contributions to food-related behaviours and learning and memory is investigated. In the first study, we map FOR protein distribution patterns in the adult brain and use this knowledge to demonstrate a neural-specific function for the for gene in adult food-related behaviour. In the second study we demonstrate a novel role for for in the regulation of naturally existing differences in fly learning and memory in the mushroom bodies of the fly brain. In the third study, I explore FOR distribution patterns in larval tissues. I show that FOR is expressed both in neural and non-neural tissues suggesting a distributed function for FOR in food-related behaviours in the larva. In the last study, I describe naturally existing differences in fat metabolism in the Drosophila larva fat storage tissue. FOR is expressed in the fat storage tissue and may regulate lipid packaging, a trait linked to foraging. In general, my thesis is a cellular and neurogenetic analysis of natural variation in behavioural and physiological traits of D. melanogaster. The functions of FOR in food-related behaviours, nutrient physiology and cognition are conserved across taxa. The findings of this thesis should provide a framework to understand these phenomena in a wide range of organisms.

It is now well accepted, through the use of mutational studies, that genes influence behavioural variation. However, we have little knowledge of the cellular and neuronal mechanisms underlying the effects of specific genes. This thesis broadens our understanding of the neurogenetic underpinnings of naturally occurring differences in behaviour using the genetically tractable model organism Drosophila melanogaster. The thesis focuses on allelic variation at the foraging (for) gene which influences both larval and adult behaviour. In particular, for’s cellular/neural contributions to food-related behaviours and learning and memory is investigated. In the first study, we map FOR protein distribution patterns in the adult brain and use this knowledge to demonstrate a neural-specific function for the for gene in adult food-related behaviour. In the second study we demonstrate a novel role for for in the regulation of naturally existing differences in fly learning and memory in the mushroom bodies of the fly brain. In the third study, I explore FOR distribution patterns in larval tissues. I show that FOR is expressed both in neural and non-neural tissues suggesting a distributed function for FOR in food-related behaviours in the larva. In the last study, I describe naturally existing differences in fat metabolism in the Drosophila larva fat storage tissue. FOR is expressed in the fat storage tissue and may regulate lipid packaging, a trait linked to foraging. In general, my thesis is a cellular and neurogenetic analysis of natural variation in behavioural and physiological traits of D. melanogaster. The functions of FOR in food-related behaviours, nutrient physiology and cognition are conserved across taxa. The findings of this thesis should provide a framework to understand these phenomena in a wide range of organisms.

No description available.

No description available.

The contagious nature of the black-tailed prairie dog (Cynomys ludovicianus) jump-yip display may provide information to signalers and receivers regarding the vigilance of neighbours. Videotaping jump-yip bouts and the behaviour of both bout initiators and respondents within those bouts provided evidence that: 1) individuals became vigilant immediately following jump-yip production, but exhibited minimal changes in their immediate post-jump-yip behaviour with changes in the characteristics of the preceding bout, 2) bout initiators spent more time actively foraging and exhibited vigilance behaviours less frequently with greater levels of response in the preceding jump-yip bout, 3) respondents spent more time actively foraging and less time vigilant following bouts with greater response. These results suggest that black-tailed prairie dogs base behavioural decisions at least in part on the characteristics of their jump-yip bouts and thus the jump yip display may provide information about the vigilance of group members.

Several parasites that require two or more hosts to complete their life cycles are known to manipulate host behaviour, enhancing their transmission to the next host. The intertidal snail, Littorina sitkana, is host to a diverse assemblage of parasites dominated by trematodes. Trematodes often use snails as first intermediate host and vertebrates as definitive host. Trematode infections can affect host behaviours such as dispersal and foraging. I identified four sites in Barkley Sound that varied in trematode prevalence and species richness. I measured dispersal of snails at these sites and in the laboratory to assess effects of trematode infection on behaviour. I measured feeding rate under laboratory conditions. Trematode effects lowered snail grazing activity at three of the four sites studied, suggesting trematode infection lowers feeding rate of L. sitkana, potentially affecting algal composition of the intertidal zone. Infected male snails travelled longer distances in some sites but shorter distances in others. There was an almost significant effect of trematode infection on vertical displacement of L. sitkana in the field. I estimated survival rates on each site through intensive capture-mark-recapture experiments. There was differential survival among sites, but no negative correlation between survival estimates and trematode prevalence. / Graduate / 0718 / 0329 / 0472 / mayala@uvic.ca

Free-living vertebrates likely encounter many stressors throughout their lifetime, from fighting off a predator to coping with unpredictable weather. As a result, vertebrates will mount an acute response to the stressors. Here, we outline previous research conducted in behavioral endocrinology and stress physiology as it relates to our research. We then discuss our study with white-crowned sparrows (Zonotrichia leucophrys) in Tioga Pass Meadow, in which we examined how the acute stress response affects foraging behavior 24 hours after a stressor. In birds that underwent a stress series, we found there to be a significant 57% decrease in foraging behavior 24 hours following the stressor. Additionally, we found no significant difference in foraging of unstressed birds during this same time frame. Our findings suggest that the acute stress response in this species causes a reduction in foraging activity 24 hours following a stressful event.

Flodpärlmusslan (Margaritifera margaritifera. L) har en obligatorisk fas i sin komplexa livcykel där den lever som parasit på antingen öringens (Salmo trutta, L) eller laxens (Salmo salar, L) gälar. För värdfisken skulle detta kunna innebära en ökad energikostnad när den födosöker i rinnande vatten. Öringens furagering består i att den finner en utgångspunkt (eng. focal point) i strömmen utifrån vilken den fångar sina byten. I denna studie undersöks det om en infektion av flodpärlmusslans glochidielarver på öring påverkar öringens födointag och hantering av födan. Sextio årsungar av öring infekterades med glochidielarver av känd koncentration, och deras födosökning mättes över en 10-veckors period för att bedöma effekten av den växande mussellarven i jämförelse med en icke-infekterad (kontrollgrupp) grupp fiskar. Individuella födoförsök, tio försök per mätningstillfällena, utfördes i ett strömakvarium där en enskild öring matades med drivande föda i fem minuter. Bytet släpptes ned i strömmen med två sekunders intervall, antalet byten räknades och furageringsbeteendet observerades. Födoförsöken genomfördes med två veckors intervall. Vid försöken hittades inga signifikanta skillnader med avseende på: 1) antalet fångade byten, 2) proportionen av fångade byten av försökets första tre minuter, eller 3) de rumsliga aspekterna av öringens utgångspunkt. Vidare uppmättes ingen signifikant effekt av tid på furageringsframgången på den infekterade gruppen jämfört med kontrollgruppen. Däremot var det ett högre antal infekterade individer som spottade ut byten jämfört med kontrollgruppen. Skillnaden i utspottade byten pekar på att infektionen har en negativ påverkan på fiskarnas furageringsförmåga. Dock visade försöken inga resultat som stödjer tidigare studier där signifikant skillnad erhållits med avseende på födointag. Förklaring till detta kan finnas i metodskillnader mellan denna och tidigare studier, inklusive skillnad i typ av byte, strömakvarier, ursprungsström för musslorna och öringen och infektionsgrad hos de infekterade fiskarna samt kontrollgruppen. / The freshwater pearl mussel (Margaritifera margaritifera, L) has a mandatory phase of its complex life cycle where it lives as a parasite on the gills of either trout (Salmo trutta, L) or salmon (Salmo salar, L). For the host fish this could mean an increased cost when it forages in running water. The trout´s foraging consists of finding a focal point in the stream from where it catches its prey. This study examines whether an infection of the freshwater pearl mussel´s glochidium larva on the gills of brown trout affect trout foraging. Sixty juvenile (0+) brown trout were infected with glochidium larva of a known concentration, and trout foraging behaviour was measured over a 10-week period to assess the effects of the growing mussel larvae of the fish compared to non-infected (control) fish.  Individual feeding trials, ten replicates for each session, were conducted in a stream aquarium where a single trout was fed drifting prey for five minutes. The prey were released into the stream every two seconds, the number of prey captured was counted, and the foraging behavior was characterized. Feeding trials were conducted at two-week intervals. No significant differences between the infected and control groups were found for: 1) the number of prey eaten, 2) the proportion of prey eaten during the first three minutes of the trial, or 3) location of the focal points. Furthermore, there was no significant effect of time on foraging success of the infected group compared to the control group. However, there was a higher number of infected individuals who spat out the prey compared with the control group. The difference in rejected prey suggests that the infection has a negative impact on the fish’s foraging ability. However, the results of this experiment do not support previous studies, where a significant difference was obtained with respect to food intake. This might be explained by differences in experimental protocol between this and previous studies, including differences in prey type, stream aquaria, stream origins of mussels and trout, and the infection status of infected and control fish.

The contagious nature of the black-tailed prairie dog (Cynomys ludovicianus) jump-yip display may provide information to signalers and receivers regarding the vigilance of neighbours. Videotaping jump-yip bouts and the behaviour of both bout initiators and respondents within those bouts provided evidence that: 1) individuals became vigilant immediately following jump-yip production, but exhibited minimal changes in their immediate post-jump-yip behaviour with changes in the characteristics of the preceding bout, 2) bout initiators spent more time actively foraging and exhibited vigilance behaviours less frequently with greater levels of response in the preceding jump-yip bout, 3) respondents spent more time actively foraging and less time vigilant following bouts with greater response. These results suggest that black-tailed prairie dogs base behavioural decisions at least in part on the characteristics of their jump-yip bouts and thus the jump yip display may provide information about the vigilance of group members.

<p>Sea turtles are long lived marine species that are currently endangered because their life history and population dynamics hinder them from withstanding modern anthropogenic threats. Worldwide, fisheries bycatch in on the major threats to the survival of sea turtles and that is also the case in the Eastern Pacific. To establish regional conservation priorities for the mitigation of bycatch, it is essential to first obtain a comprehensive picture of the regional sea turtle bycatch situation. This comprehensive analysis was lacking for the Eastern Pacific; therefore one component of this dissertation (the first chapter) is focused on delivering a regional bycatch analysis for the Eastern Pacific. A literature review was conducted to obtain numbers of turtles captured, frequencies, bycatch and mortality rates per species and country in trawl, longline, and gillnet fisheries, and to compile results of mitigation measures. Moreover, estimates for current annual capture rates in trawl fisheries were obtained and compared with population numbers. </p><p>This regional bycatch used all the information compiled and synthesized to give conservation priorities at the regional level. The review underlines the high bycatch rates in trawls for Costa Rica, Guatemala, and El Salvador and the detrimental impact that these captures could have specially for hawksbill Eretmochelys imbricata due to its reduced population numbers and for green turtle Chelonia mydas due to its highest mortality rate. It also emphasizes the continuous lack of use of TEDs as a bycatch mitigation measure. In longline fisheries, the review identifies the high bycatch rates in pelagic longline fisheries of Costa Rica, Ecuador, and Nicaragua in a global context but given that olive ridley Lepidochelys olivacea is the most common species captured in these countries, it highlights the capture of loggerhead Caretta caretta and leatherback Dermochelys coriacea off Peru and Chile due to their small population numbers. Bottom longlines have high mortality rates compared with pelagic longlines in the region and the review identifies a need for further research in this area due to the scarce information but high mortality rates. The review also noted that some mitigation measures for pelagic longlines like circle hooks and hooks with appendages could bring improvements in the mitigation of bycatch in longline fisheries in the region, there is still considerable work to be done in technology transfer, sea turtle handling, and estimates of post-release mortality rates. </p><p>For gillnet fisheries, the most important highlight is how little information exists for the region given the high rates of bycatch for sea turtles in this gear. However, the difficulties of studying bycatch in highly dynamic and artisanal fisheries are recognized as the major impediment for this situation. Nevertheless, the high bycatch rates in areas where sea turtles congregate in high numbers like in foraging grounds for loggerhead in Baja California, Mexico and for greens in Paracas and Sechura, Peru, calls for either gear modifications (which has not been that successful), change of gear, or areas closed for gillnets. </p><p>The second half of the dissertation is focused on foraging ecology of oceanic sea turtles in the Southeast Pacific Ocean. Sea turtles in the oceanic stage are the least known stage due to the difficulty of accessing these individuals. However, it is a very important stage in the life cycle and can be critical for the population dynamics of sea turtles as some population models have shown. Therefore, this dissertation is filling a gap in the life cycle of sea turtle populations in the Eastern Pacific. </p><p>To study foraging ecology, we used Stable Isotope Analysis (SIA) of turtle tissues as well as potential prey items from the oceanic realm. SIA is a great tool because it gives an integrated view, from days to weeks, of prey from a consumer tissue. SIA also can be used to link consumers to habitats when elements that have spatial trends are used. In chapter two, we investigate the foraging ecology of three species of sea turtles to compare trophic status and to observe if spatial patterns were shown in the SIA signatures of sea turtles. To our knowledge this is the first study employing SIA to research the ecology of three species of sea turtles from the same time and space. Our results show that spatial patterns in delta15N and delta13C were observed in sea turtle's tissues as correlations with latitude. We also found that loggerhead's signatures differed significantly from green and olive ridleys, especially in terms of delta15N. Loggerheads had higher values of delta15N and also a wider nitrogen trophic niche. Greens and olive ridleys were similar in isotopic nitrogen values but they were significantly different in carbon. When analyzing a smaller group of animals captured in a more restricted area, nitrogen differences were not found which suggests that latitudinal spatial patterns play an important role in the nitrogen signature. On the contrary, carbon signatures still differed among turtles in the restricted area which suggest that the inshore-offshore trend is strong and made us conclude that loggerheads are restricted to oceanic areas but that greens and olive ridleys could be using both coastal and oceanic areas.</p><p>In chapter three, we conduct a mixing model analysis using the Bayesian program SIAR to identify the most important prey items for green, olive ridley, and loggerhead off Peru. Also, we wanted to identify the contribution of longline baits in the diet of oceanic turtles. The analysis was restricted to the central zone of our study area to avoid spatial trends in nitrogen. To use as sources in the model, we collected potential prey items offshore Peru during trips on longline fishing vessels and obtained their stable isotope signatures. Results from our mixing models show that for greens and olive ridleys, crustaceans, mollusks, and coastal Ulva (indicator of coastal prey) were the only important food items. In the case of greens, crustaceans had a very high proportional contribution and due to the fact that nitrogen values of crustaceans were the lowest ones among the sources it seems that greens would be eating in a lower trophic level. The importance of coastal Ulva for greens and olive ridleys is a confirmation of our findings from chapter two where we suggest that these two species could be using oceanic as well as coastal areas. </p><p>Results for loggerheads showed cnidarians, mollusks, mackerel and squid bait as foraging items and highlights the differences among this species and the other two. The lack of importance of coastal Ulva again suggests that loggerheads remain only in oceanic areas off Peru. Moreover, the importance of mackerel and squid, the most common longline baits, suggests this species is the one interacting the most with longline fisheries and that cumulative effect of multiple interactions could have a detrimental effect in this population.</p> / Dissertation