Archive for January 2012

Of Sequences and Spotted Turtles…   Leave a comment

All those Spotted turtle DNA samples we collected in the spring have now been processed in the Laboratory of Molecular Studies at the Royal Ontario Museum. This lab work was completed during the fall, and now it’s time to see what our results can tell us about Ontario’s Spotted turtle populations! The markers we use are called microsatellites, and here’s how it works:
“Microsatellites” are specific sections of DNA which don’t code for anything and contain repeating sections that are only a few nucleotides long. Nucleotides are the building blocks of DNA – the bits that make up the DNA sequence. DNA is made up of four different nucleotides called adenine, guanine, cytosine and thymine – abbreviated A, C, G and T. Because microsatellites contain these repeats, the DNA is not always accurately copied in these sections. Sometimes, a microsatellite which contains 6 repeats is miscopied so that the new DNA strand contains 5 or 7 repeats instead.
The reason this is useful information is that every turtle (or person) has 2 copies of each microsatellite, each of which may have a different number of repeats. These differently sized copies are called alleles. The alleles you (or a turtle) carry are inherited from your parents. For example, if your mother has an allele with 17 repeats and another allele with 10 repeats at a particular microsatellite, then you inherited either the copy with 17 repeats or the copy with 10 repeats. You also carry a copy of one of your father’s two alleles. Your kids will carry a copy of one of the two alleles you got from your parents, and so on.
You already know that the length of the alleles changes slowly over time as microsatellites are occasionally miscopied. This means that when two groups of turtles are separated, the genetic profiles of these different populations gradually start to drift apart as they begin to contain different alleles from one another. As a result, each population ends up with a unique genetic fingerprint or profile. This process can take many generations and turtle’s have very, very long generation times! However, our results are showing that the genetic profile of some Ontario Spotted turtle populations have already become significantly different from one another.
These results are exciting for several reasons. They will tell us about historic connections between populations because we can see which populations which are now fragmented and isolated from one another are the most similar. And they will allow us to take our next step and build an assignment test, which will allow us to assign confiscated, poached individuals back to their population of origin. This test is in the works… more to come soon!
– Christina Davy

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Posted January 24, 2012 by thinkingturtles in Uncategorized

Where are they now?   4 comments

                As we’re all painfully aware, we’re heading into Ontario’s coldest time of year. Although the cold came late this year, it has arrived with a vengeance and all across the province waterways are freezing over. Safely tucked into muddy lake floors or burrowed deep under grassy tussocks in fens and marshes, our turtles are hibernating. This may seem to be a relatively safe season for turtles. Predators may be less likely to find them while they are hidden in their hibernation sites, and as long as everything stays stable, they can just ride out the winter cold until it’s time to emerge in the spring. And there’s the catch – it’s only safe if conditions are stable!

                Overwintering turtles and other aquatic wildlife depend on a constant supply of oxygen in the water to make it through the winter, as well as the water they are in remaining unfrozen. Some species require less oxygen than others and can tolerate changes in oxygen levels, surviving even when conditions are almost anoxic (“anoxic” means there is no available oxygen). However, if the oxygen levels really plummet even these species are likely to run into trouble. And if water freezes solid around hibernating turtles or fish, ice crystals can form in their tissue rupturing cells and causing serious injury and even death.

                So choosing a good hibernation site means choosing somewhere where the water conditions won’t change too much over the course of the winter.

                How does this relate to turtle conservation? Well, one way in which we can help protect turtles and other aquatic wildlife over the winter is by protecting our cooling and frozen wetlands from major disturbances. If wetlands are modified over the fall or winter in such a way that water levels change, the wildlife hibernating in them can be seriously affected. In severe cases, for example where water levels are dropped suddenly after turtles and other animals have already entered hibernation, sudden changes in water levels can cause huge die-offs. When the water under the ice becomes anoxic this can lead to large-scale fish kills and other problems, and since anoxia happens more quickly when there is less water available to hold the remaining oxygen, anoxic conditions develop more quickly when water levels drop.

                So although we are (sadly!) in a fairly turtle-free time of year, you can still help to protect Ontario turtles by keeping an eye on your local wetlands and making sure that any big changes that have to be made to them get saved until the spring!

 

–Christina Davy

Posted January 3, 2012 by thinkingturtles in Uncategorized

Happy New Year!!   Leave a comment

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Posted January 3, 2012 by thinkingturtles in Uncategorized