Scientists discover ‘mixed’ lizards in Puerto Rico

In school you will learn about natural selection and how, over millions of years, genetic, geographic and environmental factors Wednesday They can contribute to the formation of new species that are better adapted to the environment.

However, there comes a time when new species are no longer able to mate and reproduce. In other words, they are genetically isolated. For example, a dog and a cat cannot have “seals”.

But there are times when new species are still similar enough to reproduce and create hybrid (“mixed”) offspring. For example, a guinea fowl and a rooster can be crossed to produce “chicks.”

solyanka genetics hybrid organisms is usually a problem. Some die before or shortly after birth. If they reach adulthood, most are not very successful and cannot reproduce.

But from time to time hybrid organisms get into the “lottery”. evolutionary” and turn out to be better prepared for the environment than their parents of different species. One such case is happening right now in Puerto Rico with two lizards..

The two species that have mated are the garden lizard (Anolis pulcellus) and mountain garden lizard (Anolis circles). Although A. pulcellus prefers to live in warm and sunny places with grass and A. Circles It is most often found in the shade of forested areas; scientists saw both species throughout Puerto Rico, or so they thought.

A group of researchers, among whom Puerto Ricans stand out Javier Rodriguez Robles (University of Nevada at Las Vegas) and Manuel Leal (University of Missouri at Columbia), published in November in a professional journal. Molecular ecologygenetic analysis of hybrids A. pulcellus And A. Circles.

Scientists have confirmed that populations A. Circles They are common throughout Puerto Rico. However, although the phenotype (physical characteristics) A. pulcellus This made them think that these lizards also live throughout the island, but the reality is different.

In terms of genotype (genetic characteristics that are not always visible), hybrid lizards conquered the entire region in the west, along an imaginary line crossing approximately Kamui before Yauco. These hybrids have adapted to the environment so well that they are almost never seen anymore. A. pulcellus cigars in western Puerto Rico.

On the contrary, to the east of the same line there is only A. pulcellus pure, with the exception of two hybrids that were identified in the El Verde area, in Rio Grande.

The researchers also found that hybrids are physically confused with A. pulcellus because they have on average only 17% genetic material A. Circles. That’s not a lot DNAespecially its location, suggests two possible evolutionary advantages.

The first benefit is mainly related to cellular and immunological functions, metabolism and leg development. allowing hybrid lizards to better utilize the oxygen they breathe and move faster.

The second advantage is thermoregulation, that is, how the lizard reacts to changes in environmental temperature. This will allow the hybrids to search for food and mates early in the morning or early at night when temperatures are cooler than in the middle of the day.. More hours of activity means more opportunities to reproduce.

This study is important for three reasons. Firstly, this shows that the genetic characteristics of an organism are not always reflected in its physical characteristics.

This discovery also leads to the question: How many other cases of hybridization in lizards (or other animals) have occurred or are occurring and have not been documented?

Finally, the success of hybrids A. pulcellus And A. Circles is a clear example of what natural selection This is not something that happened millions of years ago, but a dynamic and modern force in the island’s environment.

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The author is a professor of physics and science education at Morehead State University in Kentucky and a member of the Ciencia Puerto Rico (

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