Browsing by Subject "hybridization"
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Item Captive and Wild Observations of the Courtship and Spawning Behavior of Guadalupe Bass Micropterus treculii(2013-12-06) Enriquez, Edward JamesThe Guadalupe Bass Micropterus treculii is native to the Texas Hill Country of central Texas. It is distributed across portions of the Brazos, Colorado, Guadalupe and San Antonio River basins. The Guadalupe Bass is threatened by hybridization with non-native smallmouth bass Micropterus dolomieu. Because pure bred Guadalupe Bass are increasingly harder to find in areas where Smallmouth Bass have become established, Texas Parks and Wildlife Department developed a captive spawning program for Guadalupe Bass for supplemental stocking to counter the influence of hybridization. To determine potential mechanisms influencing hybridization in Guadalupe Bass populations, objectives were: (1) characterize nesting habitat and behavior, (2) compare courtship behaviors in native and hatchery environments, and (3) identify behaviors potentially influencing genetic diversity in offspring of hatchery fish. Initial field studies included snorkeling and visual surveys conducted during September and November in 2012 in Gorman Creek, South Llano River, Pedernales River, and the Guadalupe River; no active nests or reproductive adult Guadalupe Bass were observed. During February through May of 2013, visual surveys were repeated at the four field sites. In addition courtship and spawning behavior of Guadalupe Bass were recorded at A.E. Wood Hatchery. In both hatchery and natural environments, previously undocumented reproductive behaviors were observed. Breeding color patterns of males and females became more differentiated, aggressive behavior of males included opercular flaring and jaw locking, and individual males courted multiple females simultaneously and syntopically at nest sites. Only 50% of the available nesting mats were used because of the monopolization of females and nest sites by a few males. Frequencies were significantly different for several male and female behaviors when comparing hatchery to natural environments. The prototypical courting and spawning sequence of the Guadalupe Bass were visually represented in kinematic diagrams. Although behavioral sequences were similar in hatchery and natural sites, certain transition probabilities differed. Potential mechanisms for hybridization were: similar color pattern changes in males and females of both species, female preference in both species for larger males, similar use of nesting habitat in both species, similar reproductive behavioral repertoire, and the monopolization of nesting sites and females by males.Item The Architecture of Phenotypes in a Naturally Hybridizing Complex of Xiphophorus Fishes(2013-04-08) Johnson, James BradleyThe origin and maintenance of phenotypic variation has generated considerable interest among students of functional morphology, sexual selection and behavioral ecology. In particular, hybridization has been suggested as a phenomenon which may generate novel phenotypic variation. In this dissertation I focus on the Xiphophorus birchmanni - X. malinche hybrid system to assess the role of hybridization in altering behavioral, morphological, sexual and non-sexual traits. I determine the relationship between the sword sexual ornament and body condition to support previous work which suggests that the sword is an inexpensive means to increase apparent size. My findings support the prediction that, while body size is condition-dependent, the sword is not. I show a trend toward hybrid populations displaying increased phenotypic variance and reduced phenotypic integration in sexual ornaments and body size. These findings provide evidence for a potential answer to a central question in the study of sexual selection, that of reduced genetic and phenotypic variance in sexual ornaments as the result of persistent direction selection generated by female choice. I take advantage of reduced phenotypic integration in hybrids allowing the evaluation of locomotor performance across a broad range of multivariate trait values. Sexual ornaments did not impair swimming performance per se. Rather, the sword negatively affected performance only when paired with a sub-optimal body shape. I evaluated how natural hybridization changes the relationship between boldness and anti-predator response. In poeciliid fishes, bold individuals have increased survival in the presence of predators. This non-intuitive observation may result from bold individuals being more likely to engage in anti-predator behaviors. Counter to my prediction, bold individuals were less likely to perform a fast-start response to a predator threat. This correlation was consistent among populations and species but was only significant in hybrids. My findings suggest that hybridization could influence correlations between behavioral traits in a manner similar to that documented for morphological traits.Item The Eighth Wife's Daughter(2011-08-08) Clarke, Shavonne W.This thesis explores, through fictional storytelling, the cultural duality of individuals inhabiting Singapore prior to World War II. The primary locale in many of these stories-an actual residence known as Eu Villa-interconnects each narrative and helps to uncover the hybridization of a Chinese family (and servants) living in a British colony. Many of the stories are imparted from different perspectives: wives, children and amahs, each of them pieced together to bridge the space between Chinese heritage overlaid and intermixed with British culture. In this way, the stories of this thesis reflect on the history that preceded the distinct multiculturalism of contemporary Singapore.