I read this interesting journal article about turtle mating
habits this week. The journal article was about how climate change may pose a
unique threat to turtles by producing extreme sex ratio biases that could
ultimately lead to a population’s extinction.
Marine turtles such as the famous Green Turtle are
temperature-dependent sex determined animals. This means that the higher the
temperature, the more females are produced. In marine turtles, high female
skewed hatchling sex ratios already occur and with the predicted increase in
global temperatures, they are predicted to only rise further unless they adapt
otherwise.
A study was conducted and despite the offspring sex ratio of
95% females, there were at least 1.4 reproductive males to every breeding
female. One suggestion was that the males move between aggregations of
receptive females, an inference that was supported by the satellite tracking showing
that the male turtles may have been visiting multiple rookeries.
Therefore because of the male mating patterns, the marine
turtles may have the potential the buffer the disruptive effects on the sex
ratios that climate change has posed on marine turtle populations, many which
are already seriously threatened.
Reference
·
Wright,
L.I., Stokes, K.L., Fuller, W.J., Godley, B.J., McGowan, A., Snape, R.,
Tregenza, T. & Broderick, A.C. 2012, "Turtle mating patterns buffer
against disruptive effects of climate change", Proceedings.
Biological sciences / The Royal Society,vol. 279, no. 1736, pp. 2122-2127.
Ridley Sea Turtle Hatchlings
Photograph by Bill Curtsinger
Green Sea Turtle
Photograph by Tim Larman
It’s very interesting how climate change is affecting different organisms. You mention that Wright et al. (2012) still observed 1.4 reproductive males per females. If offspring sex ratio is so heavily biased, how come there are more males? Is this due to higher female mortality? Do you think that females will alter their behaviour to start burying eggs in areas where temperatures are likely to be cooler? Nice post.
ReplyDeleteI never knew that the temperature of the water determined what sex the females offspring is going to be. it would be interesting to find out if there was a way that we could help or fix this potential problem.
ReplyDeleteI wonder if the females going on shore to lay their eggs is increasing their mortality rate (since quite a few turtles are still hunted). Do female turtles have particular migration habits that the males visit, or do they travel together?
ReplyDeleteTasmyn, I think it would be the temperature of the sand where the turtles lay their eggs. There's a few reptiles, including crocs, where the temperature in the nest determines the sex of the offspring.
ReplyDeleteNinjaMikki: Based on the lecture we had today, small numbers of males to large numbers of females is better than the other way around if we want to see the species endure - and all the better if the males are so eager that they're travelling to mate. Thanks for sharing the results of this study - it gives me some hope, for turtles at least.