Research on lizard evolution could advance understanding of changes in all organisms, including humans

 

Lizard evolved to take on the appearance of a twig

Anolis pulchellus, a grass-bush anole from Puerto Rico is often found in the bushes at the edges of forested areas.

By Jeanne Leong

Lizards are very diverse in their form and function and can evolve and adapt to the environments they inhabit, and in some settings, evolved to blend in with the twigs they live on.

Research by Anthony Geneva, a Rutgers University‒Camden assistant professor of biology, aims to understand how lizards evolve in response to living in the four Greater Antilles islands, comprising of Cuba, Hispaniola (which includes the Dominican Republic and Haiti), Jamaica, and Puerto Rico.

Anolis sagrei is a trunk-ground anole. Commonly referred to as the brown anole, this species occurs naturally in Cuba, the Cayman Islands, and the Bahamas.

Anolis sagrei is a trunk-ground anole. Commonly referred to as the brown anole, is found in Cuba, the Cayman Islands, and the Bahamas.

Geneva’s research also explores speciation – how new species arise from previously existing species.

“‘What are the genomics of adaptation’ is a question that is applicable to all life,” Geneva explains. “We don’t quite understand how it works, so our job is to try and build a framework for understanding what are the genomic steps that lead to adaptive changes in populations, and you can use that information to understand changes that occur in any organism.”

A computational biologist, Geneva studies a group of medium-sized lizards, called anoles, which live in the southern part of the United States as well as the Caribbean, Central America, and South America. Four hundred diverse species of these lizards have evolved in the last 50 million years, making it an attractive group for researchers to study the process of evolution.

Geneva says this group of lizards is a textbook example of adaptive radiation, a process where adaptation and speciation co-occur and create large groups of organisms that are very diverse in terms of their form and function. In the four islands of Greater Antilles, four separate adaptive radiations have occurred, and on each island, evolution has shaped lizards living in particular habitats.

For example, the lizards that live high in the canopy of the trees on each of these islands have separately evolved very large limbs and bodies, and enlarged adhesive pads on the bottoms of their toes like geckos, another lizard species. Geneva says the adhesive allows them to adhere to surfaces, likely to prevent falls that would be harmful to them.

Anthony Geneva

Anthony Geneva

Similarly, lizards that live on twigs on each island have evolved over millions of years of adapting to their environment. These anoles have short legs, elongated bodies, and color patterns that look like the branches they are standing on. The twig anoles on each of the Greater Antillean islands appear very similar and move in the same way, but they are not closely related to one another.

“These lizards are strikingly similar to the degree that, prior to the availability of genetic analyses, scientists – even specialists who study these animals – weren’t able to fully distinguish them from one another as distinct,” says Geneva. “Only through the use of genetics, which we can use to trace the genealogy of these animals, are we able to discover that they evolved independently.”

Geneva is exploring the genetic changes that occurred for lizards to repeatedly evolve these specialized forms on separate islands.

In his Rutgers–Camden research lab in the Joint Health Sciences Center in Camden, his team will conduct a massive amount of whole-genome sequencing on up to 350 species. The researchers will perform advanced computational analyses on the genome sequences, through the Rutgers Office of Advanced Research Computing, to try to identify the regions that are important to those species’ traits.

Lizard that evolved to resemble a twig

Anolis angusticeps from the Bahamas and Cuba, have evolved to be less conspicuous on the tiny twigs they typically inhabit.

Before the pandemic travel restrictions began in early 2020, Geneva traveled to numerous locations to collect many of the lizards, but when he started his Rutgers‒Camden lab in the summer of 2020 during the COVID-19 lockdown, his research and travel to retrieve lizard samples were suspended.

At a time that required creative ways to accomplish goals, Geneva hired a graduate student from the University of Kansas to gather specimens from the natural history museum on that campus and ship them to Camden for analysis.

Now, his lab is starting with his team in place – one Ph.D. student, two master’s students, a post-baccalaureate researcher, and three Rutgers‒Camden undergraduate students – who will examine lizards collected from the Greater Antilles islands.

A five-year, $368,000 National Science Foundation grant supports Geneva’s research at Rutgers–Camden, along with the efforts of collaborators at Washington University in St. Louis, the University of Georgia, and two colleagues from South Africa. The researchers from South Africa, who are studying chameleons, are scheduled to come to Rutgers‒Camden in the fall for four months to learn molecular computational work so that they can apply the same analyses in their research.

 

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