Have you ever wondered how our friends the sleepy sloths reproduce? Well now is your chance to learn about the Brown-throated three-toed and Hoffmann’s two-toed sloths mating journey. Looking for a mate is not easy especially in the Caribbean coast of Costa Rica, female sloths are looking for the best traits to pass down to their offspring so they can survive. So how do they figure out which male sloth to pick? Who will receive a rose from the female sloth?
In the research study done in Costa Rica over the course of four years, February 2010-May 2014, mating choices were studied in sloths. Researchers wanted to record how female sloths decided on a certain male, they were able to do this by tracking the sloths they were studying with unique PIT tags and marking them with colored collars. There was three stage of sloths identified as juvenile, subadult, or adult using this system they captured 111 Brown-throated three-toed sloths and 275 Hoffmann two-toed sloths from trees. This was to be able to identify who was sexually mature and if they were the offspring or parent. Once a baby sloth was born the researchers would test the DNA and conduct PCR reactions to confirm who the father was. In order to identify the mother, the offspring only needed to share one allele. Every time a female sloth would reproduce offspring researchers would check if it was in the same location as the first time and if it was with the same male. In order to evaluate this they would use a chi-square test and then graph it to see if the results were skewed or not. Female sloths go through a process when picking a mate, they think about mating with multiple males to reduce the risk of infanticide and create genetic diversity. What was commonly found was females would mate with the same male because they were in the same home range as that male. If a female changed her home range then the father of the offspring would be different. Females would only go back to the original mate if the survival of the first offspring was successful.
So who will the female sloth give her final rose to and pick to be her mate? Is it the male who is close in range or the male who has better genetic diversity? For both species of sloths there was a range of how they mated. The Brown-throated three-toed sloth was 25% more likely to mate with multiple partners over two breeding seasons which is a strategy they used in order to select a higher quality male. The results of this study show that female sloths do not randomly pick a male to mate with but do so depending on where they are residing at the time, and if the male has genetic diversity. This study was done over a long time to study more than one breeding season to fully understand the reasoning behind the sloth mating process. Female sloths put a good amount of thought into who they will reproduce with and want to make sure their offspring survive. In the end, the rose goes to the male who is closest and has the best genes.
Garcés-Restrepo, M.F., Peery, M. Reid, B., & Pauli, J. N. (October 3, 2017). Individual reproductive strategies shape the mating system of tree sloths. Journal of Mammalogy, 98(5), 1417-1425. Retrieved October 13, 2014, from https://doi.org/10.1093/jmammal/gyx094.
