Browsing by Author "Ogutcen, Ezgi"

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    Diversification in Monkeyflowers: An Investigation of the Effects of Elevation and Floral Color in the Genus Mimulus
    (2014-01-05) Ogutcen, Ezgi; Hamper, Brooklyn; Vamosi, Jana C.
    The vast diversity of floral colours in many flowering plant families, paired with the observation of preferences among pollinators, suggests that floral colour may be involved in the process of speciation in flowering plants. While transitions in floral colour have been examined in numerous genera, we have very little information on the consequences of floral colour transitions to the evolutionary success of a clade. Overlaid upon these patterns is the possibility that certain floral colours are more prevalent in certain environments, with the causes of differential diversification being more directly determined by geographical distribution. Here we examine transition rates to anthocyanin + carotenoid rich (red/orange/fuschia) flowers and examine whether red/orange flowers are associated with differences in speciation and/or extinction rates in Mimulus. Because it has been suggested that reddish flowers are more prevalent at high elevation, we also examine the macroevolutionary evidence for this association and determine if there is evidence for differential diversification at high elevations. We find that, while red/orange clades have equivalent speciation rates, the trait state of reddish flowers reverts more rapidly to the nonreddish trait state. Moreover, there is evidence for high speciation rates at high elevation and no evidence for transition rates in floral colour to differ depending on elevation.
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    The Effects of Dispersal and Pollination on Plantaginaceae Diversification
    (2016) Ogutcen, Ezgi; Vamosi, Jana; Harder, Lawrence; Rogers, Sean; Zelenitsky, Darla; Cota-Sanchez, Hugo
    The rich diversity of flowering plants can be explained by a variety of mechanisms, including geographical distribution, range expansion, and floral variance, which correlates with different biotic pollination forms. Plantaginaceae is an ideal model to examine these mechanisms providing the angiosperm diversity, as the family has diverse distribution patterns both in the Old World and the New World, and the family has representatives of many different pollination syndromes. Using molecular phylogenetics, ancestral reconstructions, and phylogenetic modeling and hypothesis testing, this study aimed to investigate the factors affecting the macroevolution of the angiosperm family Plantaginaceae. With 683 species from 72 genera, and a total of 6996 characters from 5 different molecular markers, the phylogenetic reconstruction revealed that Plantaginaceae have 12 strongly supported monophyletic tribes. The family was inferred to have a New World origin, and experienced several long-distance dispersal events between the Old World and the New World. In some cases, these long-distance dispersals were linked to chromosome number changes in the family. Sympatric speciation was shown to be a significant diversification mode in the family, which had some heterogeneity in terms of speciation rates among the tribes. These diversification patterns were not correlated with geographic distribution, as diversification rates in the Old World and the New World were similar. However, long-distance dispersals are found to be the main drivers of speciation within the family. Lastly, pollination was shown to have no effect on diversification in the tribe Antirrhineae In summary, this study investigated the diversification patterns within the diverse angiosperm family Plantaginaceae. Since its origin in the New World approximately 48.81 mya, the family has experienced several long-distance dispersal events between the Old World and the New World. Along with the changes in chromosome numbers, long-distance dispersal was found to be a strong contributor to the diversity in the family.