Population dynamics of Microtermes (Isoptera; Macrotermitinae) are investigated in the Southern Guinea savanna vegetation zone of Nigeria. Study sites were primary woodland, long-term maize and a randomised block experiment established from secondary woodland with woodland, pasture, sweet potato, groundnuts, yam and maize. The species assemblage Comprised of Microtermes allleo, Microtermes n.sp. c., Microtermes grassei, Microtermes/epidus, Microtermes subhyalinus. 2 Microtermes abundance and distribution (n/m2) to a soil depth of 1 metre are examined in Chapter Four. Community structure differed with vegetation cover. Abundance was generally higher in the wet compared to the dry season and abundance.was greatest in long-term maize and higher in newly cleared and cultivated sites than in woodland. M subhya/inus was the most abundant species in all vegetation types except long-term cultivated maize where M /epidus was the most abundant species. Changes in crop alter species abundance and Microtermes community structure. Microtermes fungus comb abundance (n/m2), individual dry weight (g) and total dry weight (g/m2) to a soil depth of 1 metre in primary and secondary woodland and short and long-term maize are examined in Chapter Five. Vegetation cover had an influence on seasonal changes in the abundance, individual and total dry weights of fungus combs. M subhyalinus fungus combs showed the greatest seasonal changes, in secondary woodland and short-term maize. Microtermes foraging activity on softwood baits with season, species and vegetation is examined in Chapter Six. Seasonal differences in foraging activity were recorded but differences over time were more significant. Foraging activity differed with vegetation and species. Percentage of baits attacked by species as a proportion of the total number of baits attacked by all species was the best indicator of foraging activity. Non-random foraging was identified for Microtermes with positive associations among M. subhya/inus, M. aluco and M. lepidus. Microtermes foraging activity on baits is compared with soil abundance in Chapter Seven using diversity indices and simple linear regression analysis. Foraging activity can give a more accurate indication of species richness than soil sampling. Foraging activity can be correlated positively with soil abundance, most significantly with wet season assessments.

Endophytic fungi live within tissues of plant hosts without causing symptoms of disease. These fungi are broadly split into the taxonomically and ecologically cohesive Clavicipitaceous endophytes, which infect grasses, and the taxonomically diverse non-Clavicipitaceous endophytes, which are found in nearly all plants and have diverse ecological strategies. My dissertation has two sections: Section A investigates the intersection of Clavicipitaceous endophyte ecology with other ecological theory, including invasion ecology (Chapter II) and community ecology and climate change (Chapter III); Section B investigates the ecology of one group of non-Clavicipitaceous endophytes, the Xylariaceae, using a culture-based study in Ecuador (Chapter IV) and a next-generation sequencing based endophyte survey in Taiwan (Chapter V). Section B is centered on testing the Foraging Ascomycete (FA) hypothesis—the idea that some decomposer fungi may adapt an endophytic lifestyle to escape limitations in primary substrate in both time and space. In Chapter II, I utilized a host-specific Epichloë endophyte present ubiquitously in the European native range of the Pacific Northwest (PNW) invasive grass Brachypodium sylvaticum to test theories of invasion. In Chapter III, I examined the grass Agrostis capillaris in the context of a climate manipulation experiment in prairies in the PNW to elucidate patterns of interaction between multiple symbionts (Epichloë endophytes, dark septate root endophytes, and arbuscular mycorrhizal fungi) within single hosts across climatic variation. In Chapter IV, I began to test the FA hypothesis by examining spatial relationships of Xylaria endophytic fungi in the forest canopy with Xylaria decomposer fungi on the forest floor in a remote Ecuadorian cloud forest. In Chapter V, I build on the results from the previous study, using a novel technique to examine spatial ecology of the Xylariaceae, pairing traditional mycological collection with the preparation of a next-generation sequencing metabarcode library of endophytes over a much greater area. This dissertation includes previously published and unpublished coauthored material.

In this work, I seek to model swarms of fruit flies, drosophila melanogaster, whose flights are characterized by straight flight segments interrupted by rapid turns called saccades. These flights are reminiscent of Levy-distributed random walks which are known to lead to efficient search behavior. I build two types of model for swarms of foraging fruit flies, whose behavior depends on swarm density and chemoattractant concentration, using rules inspired by experimentally observed flight patterns. First I will present a Lagrangian model where the path of each individual fly is tracked. I will also consider an Eulerian model where the fruit fly density evolves as a function of time and position in space. I will discuss the advantages and disadvantages of the two models and the relationship between them.

The combined effects of food availability and predation risk on fish foraging behavior have been investigated via both laboratory and field experiments, primarily in temperate, freshwater systems and during daylight hours. In contrast, relatively little attention has been directed towards fish foraging decisions along subtropical shorelines, which serve as nursery grounds for a variety of economically important fishes, as well as at night, when many species emerge from refuges to feed. The mangrove-seagrass ecotone and adjacent seagrass beds constitute nocturnal feeding grounds for fish secondary-tertiary consumers. In subtropical Biscayne Bay, Florida (USA), I investigated the influences of food and risk on nocturnal seagrass use by gray snapper (Lutjanus griseus), bluestriped grunt (Haemulon sciurus), great barracuda (Sphyraena barracuda), and seabream (Archosargus rhomboidalis) along a distance gradient, spanning from the mangrove fringe to 120 m from shore. This was accomplished by conducting a series of integrated field and laboratory studies, including: (1) nocturnal seine sampling to determine fish abundance patterns in relation to the mangrove-seagrass interface; (2) fish stomach content analysis to reveal feeding habits and trophic relationships; and (3) diel field tethering experiments to explore nearshore gradients in predation pressure. With these data I tested a priori predictions of fish distributions relative to food and predation risk that were generated from foraging theory: (1) fishes will be distributed across the distance gradient in proportion to their food supply (i.e., ideal free distribution, IFD); or (2) fishes will avoid high risk areas such that their abundances will be lower than predicted by food resources in high-risk habitats (i.e., food-risk trade-off). Results revealed that fish assemblage composition differed by season and distance from shore, with the zone nearest the mangroves generally harboring the lowest densities of late-stage juvenile fishes. Stomach content analysis demonstrated that gray snapper fed on a variety of small fishes and crustaceans, while bluestriped grunt fed primarily on caridean shrimp. Seabream fed almost exclusively on vegetation and great barracuda was almost entirely piscivorous; however, seasonal shifts in diet and feeding habits were evident. Seasonal shifts in major food resource use generally did not correspond with changes in relative abundance of food supply. Seasonal trophic niche breadth differences were evident for gray snapper, great barracuda and bluestriped grunt, while niche breadth was equivalent between seasons for seabream. Based on seasonal food supply in the environment, niche breadth values did not match basic foraging theory predictions, which state niche breadth should expand as preferred food resources become scarce. Tethering experiments indicated that predation rates were highest nearest the mangrove edge and decreased with increasing distance from shore. Moreover, predation pressure at night was nearly twice as high compared to the day. Testing these data against my predictions from foraging theory, I found that none of the fishes examined (gray snapper, seabream and bluestriped grunt) were distributed according to IFD. Seabream and gray snapper avoided foraging close to the mangrove-edge, where their food was most abundant, but risk was highest. Bluestriped grunt appeared to forage randomly across the distance gradient despite spatial variation in food and predation risk. Overall, results suggest that: (1) spatial patterns of utilization of seagrass habitat adjacent to the mangrove-seagrass ecotone differs by species, life-stage and season; (2) Seasonal shifts in diet were not correlated with changes in relative abundance of food supply; (3) trophic niche breadth of late juveniles did not expand with declines in their food resources; (4) the mangrove-seagrass ecotone appears to serve as a hunting corridor for predators targeting juvenile fishes moving about the mangroves; and (5) two of the three species examined appeared to give up food in return for safety by avoiding foraging near the mangroves, despite high food availability.

Plant shape affects the ability of insect predators to locate prey by altering search paths or by providing partial refugia for prey. Changes in predator foraging efficiency can have significant consequences for population dynamic of both predators and prey. Yet, the relationship between plants and insect predators is not well understood despite its relevance to agriculture and biological control. The effect of plant gross morphology on predator foraging success was tested using multicoloured Asian ladybeetles, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), and green lacewing larvae, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), preying on pea aphids, Acyrthosiphon pisum Harris (Hemiptera: Aphididae). These predators differed in body size and therefore might be expected to have different responses to a given plant morphology. Experiments were conducted using four different pea plant morphologies (Pisum sativum L.) that differed in fractal dimension, but which were controlled for surface area. The consumption rate of each predator on each pea morph was determined by measuring the number of aphids consumed in a 48 hour foraging period at 3 prey densities. I also tracked predator search paths using 2D time-lapse photography to determine if the two predators search plants differently. I found that both predators were more successful at capturing prey on plants with a higher leaf edge to leaf area ratio (lower fractal dimension). Plants with more edges were easier for predators to grip, thus increasing their mobility and manoeuvrability. Also, plants with more edges and fewer leaf surfaces had fewer locations where aphids could hide. As a result, predators are more effective at locating and capturing prey on these morphologies.

In Kaikoura, New Zealand dusky dolphins (Lagenorhynchus obscurus) are economically and ecologically important. However, more information on key habitat requirements is needed to develop an effective management plan for them. I use systematic shore-based observations and tour operator gathered boat-based observations and review night-time foraging observations to explore dusky dolphin occurrence and movement patterns. I discuss possible influence of prey on these patterns. From January to December 2006, I conducted crepuscular observations from three clifftop stations. With these geospatial data I examined occurrence, mean speed, and linearity over seasonal, diel, and tidal temporal scales. From October 1995 to November 2006 tour guides recorded GPS locations for over 5,000 dusky dolphin groups, allowing me to examine seasonal occurrence patterns. For both datasets I quantified occurrence patterns relative to depth, distance from the Kaikoura Canyon, and distance from shore. I reviewed the three studies conducted on dusky night foraging behavior in Kaikoura. I explore the effects of seasonal and lunar-scale changes in night-time light levels on dusky dolphin foraging behavior. Duskies exhibited seasonal and diel, but not tidal occurrence and movement patterns. Dolphins were found farther offshore, in deeper water, and travelling faster in winter and approaching sunset. The areas of highest sightings density were associated with the Kaikoura Canyon, and shifted almost entirely into the canyon in winter and approaching sunset. Dolphins made sharper turns during summer. Dolphins were, on average, closer to the Kaikoura Canyon than to shore. Seasonal occurrence patterns described by tour operator data agreed with those described by geospatial data collected by shorebased observers. Duskies exhibited flexible foraging behavior and appeared to use both seasonal and lunar phase specific tactics. Night-time light levels appeared to influence dusky foraging behavior, possibly through changes in prey behavior. Prey availability and behavior patterns appeared to influence dusky occurrence and movement patterns. The dolphins' affinity for the Kaikoura Canyon may reflect a strategy to maximize access to prey.

Animals forage in complex environments in which they must constantly make decisions about which resources to approach and which to avoid. Many factors can influence these foraging decisions including perception and cognition. Predators that locate prey by eavesdropping on prey mating calls face a challenging foraging task because they must be able to identify which species-specific prey signals indicate palatable prey. My thesis investigates such foraging decisions in eavesdropping bats. The Neotropical fringe-lipped bat, Trachops cirrhosus, locates its frog and katydid prey by eavesdropping on the prey's calls. One of the prey of T. cirrhosus in Panamá is the túngara frog, Physalaemus pustulosus, that can make simple calls consisting of a "whine" alone, or complex calls which are a whine followed by 1-7 "chucks". In my first chapter I examine what components of frog calls bats use to identify and localize them. I assess how bats respond to the two components of the complex calls of P. pustulosus, and report that, unlike female frogs, bats respond to the chuck component alone but preferentially approach the whine. Next, I examine how response to prey cues is affected by prey availability by assessing the response of T. cirrhosus to geographically and seasonally variable prey. I find population and seasonal differences in response to some prey cues but not to other cues. Trachops cirrhosus can also learn novel prey cues from exposure to a conspecific tutor (social learning). My third chapter examines the conditions that influence when bats socially learn novel prey cues. I discover that bats are more likely to use social information to learn novel prey cues when the cue they are currently using to find food is unreliable. In my fourth and final chapter I address how eavesdropping can contribute to the evolution and diversification of bats by investigating the potential of eavesdropping on katydid calls for niche partitioning in two closely related bat species, the European greater and lesser mouse-eared bats, Myotis myotis and Myotis blythii oxygnathus. Together these studies highlight the role of cognition in foraging decisions and consider the consequences of eavesdropping for niche partitioning. / text

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Plant shape affects the ability of insect predators to locate prey by altering search paths or by providing partial refugia for prey. Changes in predator foraging efficiency can have significant consequences for population dynamic of both predators and prey. Yet, the relationship between plants and insect predators is not well understood despite its relevance to agriculture and biological control. The effect of plant gross morphology on predator foraging success was tested using multicoloured Asian ladybeetles, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), and green lacewing larvae, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), preying on pea aphids, Acyrthosiphon pisum Harris (Hemiptera: Aphididae). These predators differed in body size and therefore might be expected to have different responses to a given plant morphology. Experiments were conducted using four different pea plant morphologies (Pisum sativum L.) that differed in fractal dimension, but which were controlled for surface area. The consumption rate of each predator on each pea morph was determined by measuring the number of aphids consumed in a 48 hour foraging period at 3 prey densities. I also tracked predator search paths using 2D time-lapse photography to determine if the two predators search plants differently. I found that both predators were more successful at capturing prey on plants with a higher leaf edge to leaf area ratio (lower fractal dimension). Plants with more edges were easier for predators to grip, thus increasing their mobility and manoeuvrability. Also, plants with more edges and fewer leaf surfaces had fewer locations where aphids could hide. As a result, predators are more effective at locating and capturing prey on these morphologies.