This article is one of a series based on my trip to Cuba. I traveled on a People to People tour to Cuba called: Cuba Today, People and Societywith Road Scholar. www.roadscholar.org
There is so much we Americans don’t know about Cuba. On my recent trip there I traveled by bus through the Zapata Swamp on my way to visit the Bay of Pigs. I never heard of the Zapata Swamp, nor did I know about the fascinating biology that is going on in this expansive wildlife refuge. Inter species breeding is occurring between the rare Cuban crocodile and the North American crocodile, and the offspring are fertile. I thought it could not be true, until I did a little research. Here is what I found out: Scientists knew that Crocodylus acutus (the American crocodile) has mated with Crocodylus rhombifer (the Cuban crocodile) in zoos.
But recently scientists in Cuba did genetic testing in the wild to confirm that this interbreeding is happening in the Zapata Swamp. The interbreeding might satisfy the “needs” of the crocs, but it is one factor contributing to the decline and possible extinction of the Cuban crocodile. It is estimated that the genetically pure Cuban crocodile’s population is down to 3,000 individuals. The interbreeding is reducing the number of Cuban crocodiles. From the 1850’s through 1960, the species was drastically reduced due to hunting. Apparently, American crocodiles living in Cuba are related more closely (genetically) to Cuban crocodiles than to American crocodiles living on mainland Central America. This closeness has allowed the hybridization to occur. Researchers found a 1 percent genetic sequence divergence between Cuban crocodiles and American crocodiles in Cuba. They found an 8 percent divergence between American crocodiles in Cuba and other American crocodile populations living in mainland Central America. These finding reinforce the statement that American crocodiles in Cuba are more closely related to Cuban crocodiles than other American crocodile populations. According to scientists this kind of inter breeding can naturally occur in isolated species. According to Judith Rhymer (University of Maine) and Daniel Simeberloff (Florida State University)1: “Some degree of gene flow is a normal, evolutionarily constructive process, and all constellations of genes and genotypes cannot be preserved. However, hybridization with or without introgression* may, nevertheless, threaten a rare species’ existence.1” *Infiltration of the genes of one species into the gene pool of another through repeated backcrossing of an inter specific hybrid with one of its parents. To learn more about the Cuban crocodile I recommend this video and website: http://youtu.be/JUEcx900MDg http://today.ttu.edu/2011/12/cuban-crocodile-research-leads-to-500000-year-old-discovery/ 1EXTINCTION BY HYBRIDIZATION AND INTROGRESSION Annual Review of Ecology and Systematics Vol. 27: 83-109 (Volume publication date November 1996)