How Did a Gecko From Africa Cross the Atlantic Ocean?


If you see a lizard climbing the side of a house in Florida or in Central or South America closer to the equator, there’s a good chance it’s an African house lizard, Hemidactylus mabouia.

Small and brown, the African house lizard is now common in the Western Hemisphere. However, the gecko originated in Southeast Africa from Zimbabwe, Mozambique and nearby areas. So how did he cross an ocean and get here?

In an article published Wednesday Royal Society Open ScienceIn , the researchers reconstructed the evolutionary history of H. mabouia and revealed that there is a diverse collection of closely related species in Africa that includes as many as 20 lineages. They show that only one lineage – Hemidactylus mabouia sensu stricto – can successfully spread across the Americas as well as Central and West Africa.

The article also offers a new way to test an old hypothesis – that African house lizards were hiding on ships related to the transatlantic slave trade. The slave trade is also thought to have involved the slave trade. Aedes aegypti mosquito and several types of worms From the African continent to the Americas and new research further reveals the ecological impacts in addition to the human detriment.

While African house geckos are much larger than a mosquito or worm, geckos are excellent runaways. Small lizards live in crevices and can survive for some time without food, according to Ishan Agarwal, a herpetologist and author of the new paper. A single stowaway gecko with a bellyful of eggs would be enough to start a new lizard population in a new country without attracting much attention.

“People never looked at them,” said Aaron Bauer, a herpetologist at Villanova University and co-author of the paper. Many herpetologists said they view lizards as a “junk” species, meaning weed-like and uninteresting.

Dr. Bauer first considered reconstructing the evolutionary history of the African house lizard nearly a decade ago. Dr. Bauer was also aware of two articles in the 1960s that drew attention to the potential link between the gecko and the trans-Atlantic slave trade. At the time, researchers lacked the technology to test the theory; but in the 2010s, Dr. Bauer could do that.

Margarita MetallinouDr. Working with Bauer, the postdoctoral researcher helped conceptualize the project and set out to rank some examples. But then tragedy struck: In 2015, Dr. Metallinou was killed in an accident while doing research in Zambia, which hindered the project.

Dr. Metallinou’s colleagues continued the research, collecting tissue samples from museum specimens of African house lizards around the world. The final datasets included samples from 186 geckos. Dr. Agarwal, Dr. He took on Metallinou’s responsibilities and did most of the sequencing work.

Dr. Agarwal said researchers were surprised by the significant diversity of the 20 interrelated species of H. mabouia.

But despite all this diversity, only one species, H. mabouia sensu stricto, managed to colonize the Americas. All other H. mabouia lizards have limited range. This raises the question of whether sensu stricto “has special characteristics that contribute to invasiveness or is it just a matter of opportunity,” said Sarah Rocha, a postdoctoral researcher at the University of Vigo in Spain who was not involved in the study.

The authors have some theories. Unlike forest-bound lizards, in African countries H. mabouia sensu stricto is most commonly found in open areas, including open spaces and human villages. While the sensu stricto faces competition from many other lizard species in Africa, it may have spread more easily in the Americas, which has fewer native lizards.

To test the theory of the trans-Atlantic slave trade, the researchers studied the routes of the slave voyages and cross-referenced historical observations of lizards in the Americas about areas related to the slave trade. H. mabouia was recorded in the West Indies in 1643 and in Dutch-controlled Brazil more than a century after slave ships crossed over to the Americas.

The genetic results of the article also support this theory, because lizards sampled from the Americas and Africa have low genetic diversity, suggesting that lizards spread to the Americas fairly recently.

The authors caution that their genetic analysis did not otherwise exclude reptiles rafting in the Atlantic a thousand years ago.

But geographer Christian Kull of the University of Lausanne in Switzerland said this type of research has rarely found evidence of a “smoking gun”, such as the mention of a lizard in a ship’s logbook. plants carried by enslaved Africans. He was not involved in the research, but said that a lizard hiding on ships seemed more plausible than a lizard “swimming on a raft of water hyacinth overflowing from the Congo River across the Atlantic.”

The African house lizard is a common species, meaning it benefits from its proximity to humans. It lives around our buildings and preys on artificial lighting – a beacon for insects. Dr. Kull said it wouldn’t be surprising to see a gecko on a ship accordingly.

Dr. It’s not the gecko’s fault that it has been so successful in surviving all over the world, as Kull saw it. Common species such as geckos, rats, and cockroaches may be better understood as travelers rather than invaders. “Perhaps the invasive species are humans,” he added.


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