copyright e* productions 2006
what*
so you're probably wondering where I have been for the last 4 years, why I never come to visit you, and why you haven't heard from me in a while...allow me to explain...
- I live in Townsville. Townsville, far north Queensland, AUSTRALIA.
- I am a PhD student studying the phylogeography of widely distributed parrotfish at James Cook University.
- I am a slacker, albeit a busy one.
Right now I am working on my first chapter:
Phylogeography, biogeography and the evolutionary history of a widespread parrotfish, Scarus ghobban:
what does it tell us about Indo-Pacific reef fish evolution?
Abstract
Many coral reef organisms are widespread throughout the tropics, however the level of connectivity between these widely distributed populations is not well understood. The parrotfish Scarus ghobban is the most widespread member of the family Scaridae, and its distribution extends from the West Indian Ocean to the East Pacific. The aim of this study was to investigate the genetic structure and connectivity of S. ghobban from within its entire geographic distribution. To determine the genetic diversity and population structure, we compared DNA sequences from the mitochondrial control region among 168 individuals collected from 19 locations in 10 regions. Four genetically distinct clades were identified and demonstrated genetic differentiation between and within ocean basins. One clade contained all but three individuals from the Pacific Ocean, and more than 85 percent of west Australian individuals from the east Indian Ocean. This clade also contained almost 50 percent of individuals from Cocos Keeling Island indicating that there is gene flow from the east Pacific to Cocos Keeling Island. A second clade contained a small group of less than 15 percent of Indo-Pacific individuals sampled from east and west Australian locations. A third clade was comprised exclusively of the remaining individuals from Cocos Keeling Island, and a fourth clade contained only individuals from the west Indian Ocean and one individual from the Great Barrier Reef. The geographic affinities of these clades denote a biogeographic barrier between the west Indian Ocean and the Indo-Pacific, with east Indian Ocean populations being connected with the Pacific rather than Indian Ocean locations. In addition, the separation of east Indian Ocean from west Indian Ocean populations in two of the four clades is evidence of partitioning within the Indian Ocean. Population genetic analyses indicate late Pliocene/early Pleistocene divergence of the two major clades suggesting a radiation event that is concordant with Pleistocene sea level changes.
huh?
in a nutshell, I am looking at DNA from 2 species of fish that occur throughout the entire Indian and Pacific Oceans to determine whether each species is a single continuous species, or if each is comprised of small complexes of cryptic species (species that are morphologically very similar but genetically distinct)
to do this I first extract and then amplify the DNA using polymerase chain reaction (PCR). This gel shows me how much amplified DNA I have, as well as which samples need to be re-amplified
what I have found is quite fascinating: Scarus ghobban is comprised of 4 genetically distinct clades, each with a particular geographic affinity. What is interesting to note is that within the Indian Ocean, there is a clear split between east and west Indian Ocean populations, except for one individual from the Seychelles that shares a haplotype with an individual from the Great Barrier Reef.
It is also interesting that most individuals from the west coast of Australia do not appear to be genetically distinct from their Pacific and even east Pacific counterparts. This means that there is genetic exchange across the entire Pacific Ocean in this particular species, however over a much smaller distance between the west and east Indian Ocean, there appears to be a much more effective barrier to gene flow.
what else*
okay, so I haven't been completely swallowed by the envelope of geekdom. Since I have been in Townsville, I have also taken up rock climbing which, contrary to movies like Cliffhanger, does not involve hanging off a cliff with nothing but your hands. Here I am setting up anchor ropes to climb on.
I also enjoy another form of climbing known as bouldering in which you climb boulders only as high as you are able to jump down from.
I have made some great friends through my climbing activities here in Townsville, most notably, Paul Y. McCann, with whom I am currently residing in a lovely (and very lopsided) home in South Townsville.
