Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
4 results
Search Results
Item Removal of Bower Paint Reduces Mate Searching Females' Return Visitation to Male Bowers(2011) Hicks, Reimi Elizabeth; Borgia, Gerald; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The multifaceted courtship display of male satin bowerbirds (Ptilonorhynchus violaceus) involves several elements that have been studied in detail. However, one of their most unusual behaviors, bower painting, has received little attention. Here, I propose two hypotheses for the function of paint and use multiple approaches to test predictions made by these hypotheses. First, I assessed how natural variation in paint quantity is related to other display traits, male mating success and male physical condition. Also, I used experimental methods including a paint removal and paint transfer experiment to investigate how birds responded to changes in the quantity and quality of bower paint. I found that males with more paint had better overall bower display quality and that fewer females returned to and copulated with males whose paint was removed. These results suggest that females may assess paint quantity during mate searching and demonstrate that paint influences male attractiveness.Item The effect of relatedness on mating behavior in the satin bowerbird (Ptilonorhynchus violaceus)(2010) Reynolds, Sheila Mayo; Borgia, Gerald; Braun, Michael J.; Behavior, Ecology, Evolution and Systematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Behavior is a main component of sexual selection theory in which male competition and female mate choice influence the evolution of a species. Relatedness commonly affects behavioral interactions, but the potential for relatedness to influence sexual selection is often overlooked. Here I show that relatedness affects mating behaviors in satin bowerbirds. Bowerbirds are a model species for non-resource based mating systems in which males provide only sperm to females, and females are free to mate with their preferred males, typically resulting in high skews in male mating success. Males build stick structures (bowers) on the ground to attract, and copulate with, females. Males compete, in part, by destroying neighboring males' bowers. Females search among multiple adjacent bowers and then select subsets of these males for courtship and then copulation. Automated video monitoring of bowers allows identification of males that destroy bowers and females that visit bowers for courtship or copulation. Using microsatellite genetic markers to estimate relatedness, I show that paternity assignments based on observed copulations match the genetic sires of offspring, supporting the hypotheses that copulations occur only at bowers and that male reproductive success can be reliably estimated from observed copulations. Next, I report that competing males are less aggressive, in the form of bower destructions, towards relatives than non-relatives and that this restraining effect of relatedness on aggression favors the close spatial association of relatives' bowers. These results support the hypothesis that relatedness affects male competition and ability to maintain attractive displays for females. Lastly, I investigate the influence of relatedness on female mate choice. I show that females do not actively prefer or avoid relatives in mate choice. However, females bias the areas in which they search for mates to be inclusive of relatives and then mate randomly with respect to relatedness within their search areas, resulting in tendencies to mate with relatives in some years. This effect of relatedness on female mate searching may be due in part to the spatial association of related males, and highlights the influence of mate searching rather than active mate preferences on overall mate choice patterns.Item Active female sampling of male display predicts female uncertainty in mate choice(2009) Cendes, Linda Marie; Borgia, Gerald; Behavior, Ecology, Evolution and Systematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Information on how females use male display elements can be critical in understanding mate choice. Females often passively sample male displays, therefore female use of an element can be difficult to quantify. In satin bowerbirds, female tasting associated with male paint offers an opportunity to study how females actively assess of male display. In a preliminary study, I found that tasting was less common by females during courtships ending in copulation. This suggested that females with a greater proportion of tastes are less certain in their mate choice. I tested this hypothesis in several ways, and each indicated that a greater proportion of tasting was associated with measures suggesting mate choice uncertainty: visiting more times and more males, mating with multiple males, and switching among males. This active sampling behavior allows for examination of female assessment of a single component of male display and to predict certain female characteristics.Item Variable female preferences and the evolution of complex male displays in satin bowerbirds (Ptilonorhynchus violaceus)(2005-05-18) Coleman, Seth William; Borgia, Gerald; Behavior, Ecology, Evolution and Systematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Models of sexual selection suggest that females benefit from assessing male display traits to choose their mates, but little is known about how individual females use particular male traits in mate choice. Here I show age-specific use of male display traits by female satin bowerbirds. Male satin bowerbirds build specialized stick structures - bowers - for courtship and copulation, and decorate their bowers with objects collected from the environment. When a female arrives at a bower for courtship, males produce intense behavioral displays that can threaten females. Using a decoration augmentation experiment, I find that young females emphasize blue decorations in mate choice decisions, while old females emphasize male display intensity. These variable preferences support a novel hypothesis for the evolution of multiple male display traits. I find that age-specific preferences reflect age-related differences in female tolerance for intense male displays: young females do not tolerate high-intensity displays and are frequently startled during courtship, while old females actively solicit high-intensity displays, and are rarely startled by these displays. I find that the presence of blue decorations calms females, especially young females, though the reason for the calming effect remains unclear. I find age-related improvement in females' abilities to discriminate among males in mate choice resulting in young females choosing males with higher parasite loads than those males chosen by old females. Finally, I find that juvenile males assess the quality of adult male tutors' displays when deciding which adult males to visit for male-male courtship - the behavioral context in which young males learn their displays. This finding supports a novel hypothesis for display trait learning, and shows that juvenile males have evolved preferences used in tutor choice that parallel female mate choice preferences. Overall, my work shows that (i) multiple male display traits may evolve via variable female preferences, (ii) variable female preferences may reflect interactions between female psychology and the male display traits available for assessment, and (iii) preferences for exaggerated male display traits may be shared by both sexes, but expressed in sex-specific roles.