Portland State University
Department of Biology
SB1, rm #406

(503) 725-3801
aramakris@yahoo.com

Current Ph.D Research, updated Jan 14 2008

Trieste Dobberstein, an undergraduate at PSU, completed a very interesting project looking at genetic diversity along a small stretch of roads near Sweet Home. We're working on getting her results published. I just made some pictures of her data that you might find interesting, which I put here.

Here is a quick review of some of the preliminary data we presented at the 2005 Evolution meetings in Alaska.

And here's a pdf file of a poster I put together for a meeting in DC. It's a big file (~1400kb), so will take some time to download. The data are preliminary still, so everything should be taken with a grain of salt.

My current research with Mitch Cruzan at Portland State University focuses on the invasive grass Brachypodium sylvaticum (false brome, see map). This perennial bunchgrass is native to Europe and Asia, and grows in both shady and sunny areas.The Institute for Applied Ecology has some more information about false-brome. Also see the False Brome Working Group's webpage.

False brome is an ideal system to work with. It has a high rate of inbreeding which makes genetic analyses easier, and it started spreading out of control only in the past 30 years or so. This means that, hopefully, there won’t be a lot of genetic ‘backwash’ obscuring the genetic signatures of migration patterns.

One of the benefits of using a molecular genetic tool to study the invasion pattern is that we can infer inbreeding rates from allele frequencies. We can also help figure out the invasion pattern of false brome: whether populations spread mainly from nearby populations, or whether new populations are started by distant populations. It may be that one of the largest populations is the main source of a genotype that is super-adapted to the environment here in Oregon. Our genetic analyses should help figure that out.

Another question we will address is: Are populations started by only a few seeds, or many? This can be inferred from allele and genotype frequencies. If new populations are just as diverse as older populations, and have many alleles, it implies that many seeds travelled to and survived in the new area. However, it may be that there are only a few types of false-brome that are able to colonize new areas.

In that case, plants that are natural colonizers may have some characteristics that make them more fit than their less-colonization-prone counterparts. David Rosenthal, the postdoc in our lab, has measured some fitness-related characters (http://web.pdx.edu/~drosen/Index.html).