FORT LAUDERDALE — Many wildlife scientists worldwide need to know why certain species live longer than others. If they know the reasons behind longevity, scientists can provide vital management data to help conserve species.
Scientists at the UF/IFAS Fort Lauderdale Research and Education Center (FLREC) contributed critical research over the last 40 years of American crocodiles to a global comparative study on longevity, aging and mortality in ectothermic tetrapods.
The study, published in the journal Science, represents the first data compilation of its kind using 107 populations of 77 species from 98 research institutions. The study provides a comparative analysis of mortality in the wild – a missing piece of the puzzle in science until now.
“Just as we contemplate human evolution and mortality rates to improve longevity in science, having long-term records on these species provides a comparative history to better understand the factors, limitations and possible trends that shape aging and longevity in the wild,” said Venetia Briggs-Gonzalez, a senior research biologist who works at the Croc Docs Laboratory at FLREC.
For the comparative analysis, UF/IFAS scientists contributed results from long-term research conducted in South Florida. The team’s research — compiled over 40 years of the American crocodile as a long-lived species — depends greatly on juveniles attaining sexual maturity and becoming adults.
For a species to increase its population size, juveniles must survive that vulnerable stage to successfully arrive at adulthood. This insight is key when considering what factors enable longevity in other species that are similar.
“Crocodiles are considered key wildlife indicators because they can tell us what is taking place in an environment, as well as what has happened through evolutionary time,” said Briggs-Gonzalez.
The crocodiles of today are not vastly different from their ancestors of 200 million years ago according to historical research, she said. This makes crocodiles an important group to use in any comparative analysis when trying to determine aging and longevity among ectothermic tetrapods. Biological traits too are key factors in considering their longevity.
“Some animals live longer than others because of how they are built. Turtles and tortoises, for instance, have heavy shells that serve as protection,” said Briggs-Gonzalez. “Similarly, crocodiles have bony body armor under their skin making it difficult for a large crocodile to succumb to predation. Additionally, some lizards produce venom that give them a survival advantage. These types of protective traits allow some animals to live longer than others,” as shown in the research article.
Comparative studies of animal aging rates in the wild like this are critical in gauging the potential limits of longevity.
“The research helps scientists understand the biological and evolutionary factors shaping why some of these reptiles and amphibians age longer than others as well as help us identify patterns and similarities in current and future evolutionary questions,” she said.