Pumas in Florida – known as Florida panthers – have been isolated from all other populations of the species for many years.
By the mid-1990s, there were estimated to be fewer than 30 individuals left and this subspecies of a cat that is otherwise widespread throughout North and South America was heading towards extinction within 25 to 40 years.
As a result, in 1995, wildlife managers took a controversial decision. They translocated eight female cats from Texas to supplement numbers in Florida and, most crucially, to reverse the increasingly low genetic variability.
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Inbreeding, report scientists in Proceedings of the National Academy of Sciences (PNAS), was causing reproductive problems (defective sperm and males with testes that did not descend as they matured), as well as animals being born with holes in their hearts.
In a situation such as this, introducing fresh genes appears to be the obvious solution, but there are potential drawbacks. In this case, one was that the Texan pumas’ DNA would ‘swamp’ that of the Florida panthers, effectively replacing one subspecies with another.
Another was that the newcomers could bring their own harmful variants within their genome.
But the study in PNAS has found the local DNA has remained dominant while substantially reducing congenital defects, with a resultant substantial rise in the population. “As of 2023, the Florida panther population size is believed to range between 120-230 adults and subadults,” the study, led by Diana Aguilar-Gómez of the University of California Los Angeles (UCLA), reported.
The scientists found that, of the eight Texan pumas introduced to Florida, five produced at least 20 cubs. “At a genomic level, these panthers exhibited a nearly threefold increase in observed heterozygosity with the previous Florida generation,” the paper says.
In addition, genetic analysis of 31 panthers that were the offspring of translocated females found they retained, on average, between 59-80 per cent of their Florida ancestry.
Once found across a huge swathe of the US South East and Deep South, including Florida, Georgia, Alabama, Louisiana and Arkansas, Florida panthers were heavily hunted after 1832 when a bounty on them was introduced because of their perceived threat to humans, livestock and game animals, according to the US National Park Service (NPS).
They are now entirely restricted to a small part of south Florida – approximately 5 per cent of their original range – where they survive by hunting feral hogs, white-tailed deer, raccoons and armadillos. The introduction of the Texas cats has “restored genetic variability for a healthier, more resilient population,” the NPS says.
Find out more about the study: Genetic rescue of Florida panthers reduced homozygosity but did not swamp ancestral genotypes
Top image: Florida puma (or panther). Credit: Getty
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