Genetic study reveals that a captive-bred population could save endangered crocodile from extinction

Since this species is almost extinct in the wild, the news brings hope for the recovery of populations.

The Orinoco crocodile (Crocodylus intermedius) is a critically endangered species native to the Orinoco River basin in Colombia and Venezuela. It is one of the largest crocodilian species in the world, reaching lengths of up to seven meters. Despite its impressive size, it is also the most endangered and least-studied of the New World crocodilians.

Female Orinoco crocodile from the Roberto Franco Tropical Biological Station´s ex-situ population.

The species has faced a severe population decline due to commercial overexploitation of its skin, which was highly sought after by the fashion industry of Europe, the USA and Japan in the 20th century. As a result, the current estimated global population stands at less than 250 adult individuals.

Recognizing the critical status of the species, herpetologist Federico Medem established a captive breeding program for the Orinoco crocodile in 1971 at the Roberto Franco Tropical Biological Station (RFTBS) in Villavicencio. Currently, the RFTBS houses over 600 individuals, making it the largest stock of this species and the only one in Colombia. Remarkably, there might be more adult crocodiles kept there than in the wild. 

Despite the success of the captive breeding program, reintroduction of animals into the wild has been challenging. This is primarily due to the lack of a comprehensive genetic characterization that can determine whether the population is genetically viable and has no signs of inbreeding, which can result in reduced fitness at the individual and population level. To ensure the successful reintroduction of the species, it was crucial to have a robust and conclusive genetic assessment that confirms the population’s genetic health and viability.

“We felt a sense of urgency to determine the genetic viability of the population in order to proceed with the reintroduction of animals and establish new populations of the species in Colombia. Therefore, we conducted a comprehensive genetic characterization using fast-evolving molecular markers on a sample of 551 crocodiles,” explains Ana María Saldarriaga, a former researcher at the Universidad Nacional de Colombia who is currently pursuing a Ph.D. at Fordham University.

Female Orinoco crocodile from the Roberto Franco Tropical Biological Station´s ex-situ population.

“Our findings showed that the individuals within the population possess sufficient genetic diversity and are suitable for reintroduction efforts, as well as for maintaining and enhancing the genetic variability of the ex-situ population.”

“We demonstrated that molecular data could be used to improve the management of ex-situ conservation programs well beyond what could be achieved with pedigree information alone,” she and her colleagues write in a study just published in the journal Nature Conservation.

Female Orinoco crocodile from the Roberto Franco Tropical Biological Station´s ex-situ population.

Based on the findings of this study, the Colombian government, along with other public and private conservation institutions and agencies, can use the individuals identified in this research to initiate the establishment of new populations in regions where the species has been completely depleted.

Female Orinoco crocodile from the Roberto Franco Tropical Biological Station´s ex-situ population.

“Today, it is widely recognized that top predators, such as crocodiles, play fundamental roles in both aquatic and terrestrial ecosystems. They have a significant impact on the nutrient cycle, regulate fish populations, and contribute to important cross-ecosystem engineering processes,” stated Mario Vargas-Ramírez, professor at the Genetics Institute of the Universidad Nacional de Colombia and director of the RFTBS.

“Therefore, the reintroduction of the Orinoco crocodile to the Orinoco region is an urgent priority. Additionally, as the Orinoco crocodile is considered an umbrella species, its recovery and conservation efforts will have a positive cascading effect, protecting a large number of species that coexist in the same environment.” 

Research article:

Saldarriaga-Gómez AM, Ardila-Robayo MC, Medem F, Vargas-Ramírez M (2023) Hope is the last thing lost: Colombian captive-bred population of the critically endangered Orinoco crocodile (Crocodylus intermedius) is a genetic reservoir that could help to save the species from extinction. Nature Conservation 53: 85-103. https://doi.org/10.3897/natureconservation.53.104000

Photos by Mario Vargas-Ramírez.

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Bee populations expanded during global warming after the last Ice Age

The Australian small carpenter bee populations appear to have dramatically flourished in the period of global warming following the last Ice Age some 18,000 years ago.

The bee species is found in sub-tropical, coastal and desert areas from the north-east to the south of Australia. Researchers Rebecca Dew and Michael Schwarz from the Flinders University of South Australia teamed up with Sandra Rehan, the University of New Hampshire, USA, to model its past responses to climate change with the help of DNA sequences. Their findings are published in the open access Journal of Hymenoptera Research.

“You see a rapid increase in population size from about 18,000 years ago, just as the climate began warming up after the last Ice Age,” says lead author Rebecca Dew. “This matches the findings from two previous studies on bees from North America and Fiji.”

“It is really interesting that you see very similar patterns in bees around the world,” adds Rebecca. “Different climate, different environment, but the bees have responded in the same way at around the same time.”

In the face of future global warming these finding could be a good sign for some of our bees.

However, the news may not all be positive. There are other studies showing that some rare and ancient tropical bees require cool climate and, as a result, are already restricted to the highest mountain peaks of Fiji. For these species, climate warming could spell their eventual extinction.

“We now know that climate change impacts bees in major ways,” says Rebecca, “but the challenge will be to predict how those impacts play out. They are likely to be both positive and negative, and we need to know how this mix will unfold.”

Bees are major pollinators and are critical for many plants, ecosystems, and agricultural crops.Image2

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Original source:

Dew RM, Rehan SM, Schwarz MP (2016) Biogeography and demography of an Australian native bee Ceratina australensis (Hymenoptera, Apidae) since the last glacial maximum. Journal of Hymenoptera Research 49: 25-41. doi: 10.3897/JHR.49.8066