Date of Degree
MS (Master of Science)
Understanding the processes that generate biodiversity is a major goal of evolutionary biology. The ultimate cause of biodiversity is the evolution of barriers to gene flow between populations of organisms, but the proximate mechanisms are often more complex. I am interested in disentangling the roles of geographic isolation and ecological selection in the diversification of a species-rich genus of tropical tephritid fruit flies. Blepharoneura are highly specialized and host specific flies; most species specialize on a single plant host and flower sex although multiple species may exploit the same resource. At one location in Peru, two plant species (two sexes - four plant niches) are host to 14 Blepharoneura species. Phylogenetic analyses of mitochondrial DNA sequences reveal that some species may be diverging as a result of shifts to new host plants (suggesting possible ecological selection acting in speciation), while other species show an apparent pattern of geographic divergence in addition to or without host shifts. To further investigate these ecological and geographic signals underlying the history of Blepharoneura speciation, more rapidly evolving molecular markers are required. Here, I use microsatellites to address this question for seven Blepharoneura species (sp1, sp4, sp8, sp10, sp21, sp28, and sp30) characterized by differing patterns of host-plant use and geographic distribution. Microsatellite data indicates patterns of ecological divergence associated with host use in at least five species (sp1, sp4, sp10, sp21, sp30) and patterns of geographic divergence in all seven species.
Insects constitute >50% of the world’s species, many of which are either agriculturally or pharmaceutically important. Understanding why this group is so diverse and what generates that biodiversity could provide new insights into preserving economically important ecosystems. The ultimate cause of biodiversity is the evolution of barriers that separate populations of organisms. I am interested in discovering what barriers are important in the diversification of a species-rich group of tropical fruit flies. Blepharoneura are highly specialized and host specific flies. Most species feed on a single plant host although multiple species may exploit the same resource. For example, at one location in Peru, two plant species are host to 14 Blepharoneura species. In addition, Blepharoneura occupies a large range, occurring from Mexico to Bolivia. To examine how ecological and geographic barriers are leading to diversification in Blepharoneura, I studied seven species characterized by differing patterns of host-plant use and geographic distribution. I found patterns of ecological diversification associated with host use in five species and patterns of geographic divergence in all seven species.
x, 59 pages
Includes bibliographical references (pages 55-59).
Copyright 2015 Kristina Ottens