<p> There is a large literature discussing social influences on diet choices in rats. However, the ontogeny of social influences on diet choices is poorly understood. Early experiences have dramatic affects on the development and expression of future behaviors.</p> <p> The present research investigates whether early social experience altered the susceptibility to social influences on diet choices in juvenile Norway rats (R. norvegicus). Interactions with dam and siblings between parturition and weaning are prominent features of early rats development. It was hypothesized social behavior developed during this period and rearing pups in social isolation would disrupt the development of normal social behaviors.</p> <p> Conspecifics influence the diet preferences of others by socially interacting. The first experiment investigated whether demonstrators could influence diet choices of rats with no social experience. In terms of diet preferences, demonstrators influenced both normally reared rats and rats reared in social isolation.</p> <p> Interactions with conspecifics and exposure to diet odors without social contexts influenced the diet choices of 21 day old pups. Only interactions with conspecifics influenced diet choices of 28 day old rats. Rearing rats in social isolation may delay the onset of social specificity and the results of experiment 1 may have been the product of two different mechanisms. The second experiment investigated whether rats reared in social isolation attended to socially specific cues or to general olfactory cues. Exposure to flavored diets in a non-social context did not influence diet choices of rats reared in social isolation or normally-reared rats. Thus early social interactions do not appear to be necessary for demonstrator rats to influence the diet choices of other rats.</p> / Thesis / Master of Science (MSc)

Previous research has shown that male pigeons (Columba livia) respond with courtship displays to video playbacks of a female pigeon indicating that they 'recognize' the female as a potential mate. Courtship displays significantly decline when the head region of the female is occluded (Shimizu, 1998) suggesting that features located within the head are important for species recognition and mate selection. However, little is known about the exact visual features necessary to elicit displays. The current study examined the preference behavior of male pigeons when given a choice between photographic images of normal looking or altered female pigeon faces. The altered-face categories included: 1) enlarged or removed facial features such as the eyes or beak; 2) the eyes and beak reconfigured within the head; and 3) removed contour (outline). The results showed that subjects responded preferentially toward females with enlarged features (eyes or beak). However, subjects responded preferentially toward normal females when the alternative stimuli were faces that were missing the eyes and/or beak. Preference for normal females was also observed when females with "incorrect" configuration were shown. Finally, subjects responded significantly less to females lacking contour, even when the eyes and beak were visible. The overall findings suggest local facial components are important, although this effect diminishes if the contour of the female is not visible. These findings also suggest that pigeons attend to both local components and global configuration when they detect conspecifics and identify potential mates.

Many organisms use both vegetation structure and social cues in selecting habitats. Many species of songbirds use the presence of breeding conspecifics as a social cue and sign of habitat quality, and can be induced to settle in unoccupied habitats by artificially broadcasting breeding song, a process referred to as “conspecific attraction”. In our study, we tested response to conspecific attraction a low-density population of the threatened Golden-winged Warbler (Vermivora chrysoptera) in Highland County, VA. Response to broadcast song was observed, with a modest increase in mean male abundance at survey points within 250 meters of treatments, and mean abundance decreasing outside of this range throughout the study area. Recruitment to conspecific playback was lower in our study than observed in previous research on high-density systems. Our results suggest more research is needed of the effectiveness of conspecific attraction in low density species and that its use should be tailored to the spatial and demographic conditions of the managed population.

Most domestication hypotheses propose that dogs have been selected for enhanced communication and interactions with humans, including learning socially from human demonstrators. However, to what extent these skills are newly derived and to what extent they originate from wolf–wolf interactions is unclear. In order to test for the possible origins of dog social cognition, we need to compare the interactions of wolves and dogs with humans and with conspecifics. Here, we tested identically raised and kept juvenile wolves and dogs in a social learning task with human and conspecific demonstrators. Using a local enhancement task, we found that both wolves and dogs benefitted from a demonstration independent of the demonstrator species in comparison to a control, no demonstration condition. Interestingly, if the demonstrator only pretended to hide food at the target location, wolves and dogs reacted differently: while dogs differentiated between this without-food and with-food demonstration independent of the demonstrator species, wolves only did so in case of human demonstrators. We attribute this finding to wolves being more attentive toward behavioral details of the conspecific models than the dogs: although the demonstrator dogs were trained to execute the demonstration, they disliked the food reward, which might have decreased the interest of the wolves in finding the food reward. Overall, these results suggest that dogs but also wolves can use information provided by both human and conspecific demonstrators in a local enhancement task. Therefore we suggest that a more fine-scale analysis of dog and wolf social learning is needed to determine the effects of domestication.

Adaptation to local environments via natural selection is a powerful mechanism for population divergence and likely one of the primary causes of speciation. To understand how specific habitats shape local adaptation, it is helpful to study closely-related populations from widely differing ecosystems that have not had sufficient time to diverge by genetic drift. Throughout the following chapters I examine the distribution of morphological, behavioral, and reproductive phenotypes within and between two subspecies of the swamp sparrow. These two populations, the tidal salt marsh endemic Melospiza georgiana nigrescens and the nominant inland subspecies, M. g. georgiana were incompletely isolated from each other following the retreat of the Wisconsin glaciation. Since that time the increased nest predation, temperature, season length, salinity and tidal flow of the coastal marshes relative to inland wetlands has resulted in a number of adaptations among coastal sparrows due to natural selection, sexual selection, and phenotypic plasticity. Specifically I examine the habitat preferences of the coastal plain swamp sparrow, the difference in clutch size between the two subspecies, the rates of extrapair fertilization relative to male quality, the ecosystem-specific interactions between natural and sexual selection on plumage badges, and the role of conspecific attraction in nest placement. The environmental differences of the tidal salt marsh have played strong roles in the local adaptation and divergence of coastal plain swamp sparrows from their freshwater ancestors. Many of these divergent mechanisms may be similar among other tidal marsh endemics, although some (especially those related to sexual selection) may be specific to the swamp sparrow. In general, however, we see that the added environmental challenges of tidal ecosystems strongly alter selection regimes on a terrestrial vertebrate inhabiting this dynamic ecotone. The swamp sparrow system can further increase our understanding of how the interplay between environmental resources, sexual selection, and natural selection affects the local adaptations leading to evolutionary divergence. / Ph. D.

Conspecific brood parasitism (CBP) is a situation, when female (a parasite) lays egg or eggs in a nest of other conspecific female (a host). Then she leaves the nest and doesn't provide any subsequent parental care, such incubation and care for young. To distinguish between parasitic and host egg or young could be difficult, because there are not obvious morphological differences. CBP was documented in more than 234 species and its frequency is different between species, but also between population of the same species. The main aim of my master thesis was to describe the degree of parasitism in two population of Common Pochard (Aythya ferina). The field work was carried out from 2004-2006 in Třeboň Biosphere Reserve and form 2008-2010 in Poodří Landscape Protected Area. We found that the degree of CBP is relatively high. In Třeboň was found 72 % (41) of parasitized nests and 32 % (165) of parasitic eggs and in Poodří 93 % (39) of parasitized nests and 37 % (153) of parasitic eggs. The mean number of eggs per clutch was around 9 and mean number of host eggs per clutch was 6 in Třeboň. The mean number of eggs per clutch in Poodří was about 10, and the mean number of host eggs was also about 6. The mean number of parasitic eggs per clutch was 3 resp. 4. It was also found, that parasitized nests are...

In ecology literature, there is much data which suggests that conspecific negative density dependence (CNDD) and abiotic disturbances increase biodiversity in forests. This thesis elucidates the notion that not only do these two forces increase diversity, but they may also interact with one another in order to achieve higher levels of biodiversity. Abiotic disturbances, like fires and hurricanes, can indirectly impact conspecific effects because when these forces remove individuals from the landscape, the role of the conspecific effects will change. The interaction of these two factors in biodiversity are explored in an agent based forest simulation through a resource surface. Several different types of abiotic disturbances are simulated with either weak or strong CNDD effects in order to establish that different disturbances and conspecific effects cause certain levels of diversity. The underlying causes for the change in impact is also examined.

Many grassland songbird species exhibit sensitivity to patch size in North America’s fragmented prairie ecosystems, but the mechanisms explaining this area sensitivity are not well understood. I tested the effects of patch size and artificial conspecific location cues (song playback and decoys) on grassland songbird abundance in 23 northern tall-grass prairies in Manitoba, Canada, in 2010 and 2011. Richness and relative abundances increased with patch area; this effect was not explained by differences in local habitat structure, patch configuration, and adjacent matrix. Artificial cues elicited putative territory prospecting in small, previously unoccupied treatment patches from two focal species, Savannah Sparrow (Passerculus sandwichensis; n=3 treatment sites) and Le Conte’s Sparrow (Ammodramus leconteii; n=4 treatment sites), but not in control patches (n=3 for both focal species). Social information may influence the focal species’ settlement decisions, but the lack of permanent settlement response suggests social cues are unable to reverse their area sensitivity.

Many grassland songbird species exhibit sensitivity to patch size in North America’s fragmented prairie ecosystems, but the mechanisms explaining this area sensitivity are not well understood. I tested the effects of patch size and artificial conspecific location cues (song playback and decoys) on grassland songbird abundance in 23 northern tall-grass prairies in Manitoba, Canada, in 2010 and 2011. Richness and relative abundances increased with patch area; this effect was not explained by differences in local habitat structure, patch configuration, and adjacent matrix. Artificial cues elicited putative territory prospecting in small, previously unoccupied treatment patches from two focal species, Savannah Sparrow (Passerculus sandwichensis; n=3 treatment sites) and Le Conte’s Sparrow (Ammodramus leconteii; n=4 treatment sites), but not in control patches (n=3 for both focal species). Social information may influence the focal species’ settlement decisions, but the lack of permanent settlement response suggests social cues are unable to reverse their area sensitivity.

Background: Pollen transfer via animals is necessary for reproduction by ~80 % of flowering plants, and most of these plants live in multispecies communities where they can share pollinators. While diffuse plant-pollinator interactions are increasingly recognized as the rule rather than the exception, their fitness consequences cannot be deduced from flower visitation alone, so other proxies, functionally closer to seed production and amenable for use in a broad variety of diverse communities, are necessary. Scope: We conceptually summarize how the study of pollen on stigmas of spent flowers can reflect key drivers and functional aspects of the plant-pollinator interaction (e.g. competition, facilitation or commensalism). We critically evaluate how variable visitation rates and other factors (pollinator pool and floral avoidance) can give rise to different relationships between heterospecific pollen and (1) conspecific pollen on the stigma and (2) conspecific tubes/grain in the style, revealing the complexity of potential interpretations. We advise on best practices for using these proxies, noting the assumptions and caveats involved in their use, and explicate what additional data are required to verify interpretation of given patterns. Conclusions: We conclude that characterizing pollen on stigmas of spent flowers provides an attainable indirect measure of pollination interactions, but given the complex processes of pollen transfer that generate patterns of conspecific-heterospecific pollen on stigmas these cannot alone determine whether competition or facilitation are the underlying drivers. Thus, functional tests are also needed to validate these hypotheses.