In case anyone wondered where I've gone to and why I've not been writing recently - I left the field earlier than usual this year because I had an opportunity to come out to San Diego (La Jolla to be exact � where I am now) to analyze all the genetic samples that we�ve been taking from our leatherback girls for the past 6 years. This blog entry is to give a little bit of info about this work. As you've probably seen on our project log from time to time, we take a small skin sample from our nesting turtles - you only need a tiny bit to be able to get enough DNA to do the analysis. We've been fortunate to team up with Dr. Peter Dutton at the NOAA Fisheries Southwest Lab to do this work.
I wont go into the minute details of how the DNA is processed let's just say it takes a long time and involves moving tiny amounts of liquid around from tiny tube to tiny tube! But the general outline goes like this; we are looking at both mitochondrial DNA (mtDNA) and nuclear DNA. MtDNA is passed on only from your mother and looking at this component of DNA allows you to look at maternal lineages (moms and daughters). Each individual turtle of ours has what's called a unique haplotype (a unique sequence of nucleotides � those are the As, Cs, Gs and Ts if you remember from genetics classes - they are the basic building blocks of DNA). Using this mitochondrial method has allowed researchers around the world to provide evidence for natal homing (when turtles return to the same beach where they were born) as the same haplotypes become concentrated in certain leatherback colonies. Florida has haplotypes A and C (although I've just analyzed another 105 samples so we'll see if there are new ones - which would indicate a new maternal line). Nuclear DNA is inherited from both parents and it gives different information. To look at nuclear DNA you use microsatellites which are tiny chains of repeating nucleotides. Each turtle will have a unique set of these sequences and the result is that you get a kind of fingerprint for each turtle that is each one can be distinguished from others in the colony.
So using both these lines of investigation we hope to determine A) how many families of leatherbacks are using Juno Beach (that is, how many maternal lines there are) and B) what colony in the Atlantic are Florida leatherback turtles most closely related to? The closest nesting colonies for leatherbacks are St. Croix and Costa Rica. We think that a few turtles made the move from Costa Rica nesting beaches, found Florida and set up a new nesting rookery. Leatherbacks do this sort of thing, being the ocean wanderers that they are, it is to their advantage to seek out good new habitat. It seems that's what they've done in Florida! It will take a while before I get some results but as of today, I have nearly finished all the lab component of the work, and next week will start looking at and analyzing all the data that I've generated over the past 3 weeks. I'll keep you posted through the summertime.
