Santa Cruz Island Reserve

30 Aug, 06 AM - 31 Aug, 08 AM

I am conducting a population genetic study of California Grindelia in order to study the complex patterns of morphological diversification associated with recent radiation. In California, species of Grindelia occur in habitats ranging from salt marshes and sand dunes to serpentine grasslands and roadsides in the Central Valley. The plants in these different habitats are morphologically distinct ecotypes within the intergrading complex of California Grindelia species. There are two major ways by which the ecotypes could have evolved. It is possible that an ancestral Grindelia with a wide habitat tolerance colonized all of California and that subsequently each population adapted separately to its local habitat. Under this scenario, plants growing in a similar habitat in different parts of the state are morphologically similar because of convergent evolution. Alternatively, each ecotype could have evolved a single time and subsequently spread throughout its range. Under this scenario, plants growing in a similar habitat in different parts of the state are morphologically similar because of shared ancestry (they are each other?s closest relatives). The evolutionary history of California Grindelia probably incorporates both of these scenarios. I am going to use DNA sequence data from the rapidly changing psbA-trnH and psaI-accD regions of the chloroplast to examine the relationships of the California Grindelia. It is much easier to obtain good sequences of chloroplast DNA than it is of nuclear DNA, which often requires expensive and time consuming cloning steps prior to sequencing. In addition, different chloroplast genes share the same history because the chloroplast is inherited as a unit (unlike nuclear genes, which are on separate chromosomes), so many different chloroplast genes may be combined in the same analysis to increase resolution. I will also use length-polymorphism data from six different nuclear microsatellites, which I developed for Grindelia for a different portion of my dissertation that involves looking at gene flow between adjacent populations. Microsatellites are regions of a plant?s genome composed of a short nucleotide sequence (such as GCC) that is repeated many times (GCCGCCGC?.). These repeated sequences are particularly difficult for an organism to copy, so they change in length (by gaining or losing repeats) much more rapidly than the rest of the plant?s genome. Due to their variability, microsatellites are useful for examining the relationship of closely related species or populations within a species. In order to examine the evolutionary history of Grindelia in California, I need to examine a broad sampling of plants found throughout the state incorporating a wide range of morphological and ecological diversity. I will collect branches from three to five individuals at each location in order to sample the full range of morphological and genetic variation present in the population. These branches will be used as voucher specimens for morphological analysis and a leaf from each branch will be removed for DNA extraction and sequencing.

Visit #22281 @Santa Cruz Island Reserve

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Under Project # 22139 | Research

Phylogeographic Study of California Grindelia (Asteraceae)

graduate_student - University of California, Berkeley

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Group of 2 Graduate Student Aug 30 - 31, 2010 (2 days)

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Dorm 2 Aug 30 - 31, 2010
Private Room 2 Aug 30 - 31, 2010