How a Gecko From Africa Crossed the Atlantic Ocean

cigaretteman

HR King
May 29, 2001
71,429
50,987
113
If you see a gecko scampering up the side of a house in Florida or somewhere in Central or South America closer to the Equator, there is good chance it is an African house gecko, Hemidactylus mabouia.

Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox.
Little and brown, the African house gecko is now widespread in the Western Hemisphere. But the gecko originated in southeastern Africa, from Zimbabwe, Mozambique and nearby areas. So how did it cross an ocean and come here?
In a paper published on Wednesday in Royal Society Open Science, researchers have reconstructed the evolutionary history of H. mabouia, revealing it to be a diverse collection of closely related species that include as many as 20 lineages across Africa. They show that only a single lineage — Hemidactylus mabouia sensu stricto — was able to spread successfully throughout Central and West Africa as well as in the Americas.
The paper also offers a new way to test an old hypothesis — that African house geckos stowed away on vessels involved with the trans-Atlantic slave trade. The slave trade is also thought to have transported the Aedes aegypti mosquito and several earthworm species to the Americas from the African continent, and the new research further reveals its ecological effects in addition to its human toll.
Advertisement
Continue reading the main story


Though African house geckos are much larger than a mosquito or earthworm, geckos are excellent stowaways. The small lizards live in crevices and can survive for some time without food, according to Ishan Agarwal, a herpetologist and an author of the new paper. A single stowaway gecko with a bellyful of eggs would be enough to start a new population of geckos in a new land, without attracting much notice.


The new study showed H. mabouia to be a diverse collection of closely related species that include as many as 20 lineages across Africa, with just one of them common in the Americas.Credit... Ishan Agarwal
“People never really looked at them,” said Aaron Bauer, a herpetologist at Villanova University and a co-author of the paper. Many herpetologists, he said, consider the geckos to be a “trash” species, meaning weedlike and uninteresting.
Dr. Bauer first thought about reconstructing the evolutionary history of the African house gecko about a decade ago. Dr. Bauer also knew of two papers from the 1960s that noted the potential link between the gecko and the trans-Atlantic slave trade. Back then, researchers lacked the technology to test the theory; but in the 2010s, Dr. Bauer could do it.
Margarita Metallinou, a postdoctoral researcher working with Dr. Bauer, helped to conceptualize the project and began sequencing some specimens. But then tragedy struck: In 2015, Dr. Metallinou died in an accident in Zambia while conducting research, which set back the project.
Advertisement
Continue reading the main story



Dr. Metallinou’s colleagues continued the research, collecting tissue samples from museum specimens of African house geckos across the world. Their final data set included specimens from 186 geckos. Dr. Agarwal took on Dr. Metallinou’s responsibilities and did the bulk of the sequencing work.
The researchers were surprised at the significant diversity of the H. mabouia’s 20 interrelated species, Dr. Agarwal said.
Yet despite all this diversity, only one species, H. mabouia sensu stricto, managed to colonize the Americas. All the other H. mabouia geckos have restricted ranges. This raises the question of whether sensu stricto has “special traits that contribute to invasiveness, or if it was just a question 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 geckos, H. mabouia sensu stricto in African countries is most often found in open spaces, including clearings and human villages. Though sensu stricto faces competition from the many other gecko species in Africa, it may have spread more easily in the Americas, which have fewer native geckos.
To test the trans-Atlantic slave trade theory, the researchers studied the routes of slave voyages and cross-referenced historical observations of the geckos in the Americas with areas involved with the slave trade. H. mabouia was recorded in the West Indies in 1643 and in Dutch-controlled Brazil around the same time, more than a century after slave ships crossed to the Americas.

While the researchers couldn’t rule out the gecko rafting its way across the Atlantic Ocean 1,000 years ago, sneaking on ships during the trans-Atlantic slave trade is more likely, researchers say.

While the researchers couldn’t rule out the gecko rafting its way across the Atlantic Ocean 1,000 years ago, sneaking on ships during the trans-Atlantic slave trade is more likely, researchers say.Credit...Johan Marais
The paper’s genetic results also buttress this theory, as geckos sampled from the Americas and Africa had low genetic diversity, suggesting the geckos spread to the Americas rather recently.
Advertisement
Continue reading the main story


The authors caution that their genetic analysis does not rule out the reptiles rafting across the Atlantic a thousand years ago some other way.
But there is rarely a “smoking gun” piece of evidence, such as the mention of a gecko in a ship’s log, in this kind of research, said Christian Kull, a geographer at the University of Lausanne in Switzerland who has studied plants transported by enslaved Africans. He was not involved with the research, but said that a gecko stowing away on ships seems more plausible than a gecko “floating on a raft of water hyacinth flooded out of the Congo River across the Atlantic.”
The African house gecko is a commensal species, meaning it benefits from its adjacency to humans. It lives around our buildings and hunts by artificial lighting — a beacon for bugs. Accordingly, it would not be surprising to see a gecko aboard a ship, Dr. Kull said.
As Dr. Kull sees it, it is not necessarily the gecko’s fault that it has become so good at surviving around the world. Commensal species like geckos, rats and cockroaches may be better understood as passengers, rather than invaders. “Perhaps it is humans that are the invasive species,” he added.
 

PoopandBoogers

HR All-American
Mar 29, 2002
3,925
6,517
113
We have geckos and lizards all over here in Fl. I have 2 lizards on my porch named Elvis and Priscilla. They bang a few times a day right in front of me. The lizards are out and about eating bugs all day, except when the black racer makes his daily slither through the mulch. Once night hits, the lizards retire and the geckos come out to play. I've had a few in my house and generally I'll let them stay for as long as they want. They are excellent hunters and you won't see any trace of a fly, spider, etc as long as they are there.
 

PoopandBoogers

HR All-American
Mar 29, 2002
3,925
6,517
113
In Houston we have:

Brown Anole, Green Anole and Mediterranean House Gecko. Although, over the years I see less Geckos and more Anoles. Not sure why.

1280px-Brown_Anole_%28Anolis_sagrei%29.jpg


1920px-Anole_Lizard_Hilo_Hawaii_edit.jpg


1280px-Mediterranean_house_gecko.JPG
Going purely from memory, I believe the green anoles are native to FL and the brown anoles are not and introduced from the islands. I see less and less of the green ones now. It's sad that I'm actually shocked and excited when I even see one nowadays.
 

GOHOX69

HR Legend
Sep 26, 2009
13,656
16,824
113
We have geckos and lizards all over here in Fl. I have 2 lizards on my porch named Elvis and Priscilla. They bang a few times a day right in front of me. The lizards are out and about eating bugs all day, except when the black racer makes his daily slither through the mulch. Once night hits, the lizards retire and the geckos come out to play. I've had a few in my house and generally I'll let them stay for as long as they want. They are excellent hunters and you won't see any trace of a fly, spider, etc as long as they are there.
What type of lizards are they? Do you have iguanas? I've heard there are other lizards that came as pets and were released and now have breeding populations.
 

PoopandBoogers

HR All-American
Mar 29, 2002
3,925
6,517
113
What type of lizards are they? Do you have iguanas? I've heard there are other lizards that came as pets and were released and now have breeding populations.
Anoles and geckos. You could probably round up 20-30 easily in an average yard. Heard a clicking noise recently when trying to sleep and tracked it down to around 10 eggs in between the bedroom screen and window. We also have a small population of curly tailed lizards here, but they are mainly by the beach sand dunes. The iguanas are further down the coast, from around Ft. Lauderdale south. They are big and creepy, and those mfrs can swim.
 
  • Like
Reactions: GOHOX69

GOHOX69

HR Legend
Sep 26, 2009
13,656
16,824
113
Anoles and geckos. You could probably round up 20-30 easily in an average yard. Heard a clicking noise recently when trying to sleep and tracked it down to around 10 eggs in between the bedroom screen and window. We also have a small population of curly tailed lizards here, but they are mainly by the beach sand dunes. The iguanas are further down the coast, from around Ft. Lauderdale south. They are big and creepy, and those mfrs can swim.
I heard idiots have released tegu and monitor lizards, former pets, that are also in S. Florida. That's cool that you like these tiny reptiles.