Understanding the parallel: The identical actions of lizards propelled by natural selection

In a groundbreaking study, researchers have discovered that various animal species, including insects, fish, frogs, birds, and mammals, have evolved similar communication strategies to cope with noisy environments. This phenomenon, known as convergent evolution, was previously thought to occur mainly among closely-related species.

The study, published in Ecology Letters with the DOI 10.1111/ele.13773, focuses on the behaviour of Anolis lizards in the Caribbean and Draco lizards in Southeast Asia. The findings have implications for a wide range of animal species, as they demonstrate natural selection driving similarities between different species.

Dr Ord, an evolutionary biologist, notes that the independent evolution of these common communication strategies is even more extraordinary due to the diversity of animal groups involved. He further states that evolutionary biologists are excited about convergent evolution because it provides multiple examples of the same adaptation evolving time and time again in various animals.

The study highlights that natural selection can override past history to produce the same adaptations, such as arm-waving being favoured over subtle modifications to existing vocal calls. For instance, both the Australian velvet gecko and the Centralian blue-tongue skink, two lizard species studied in the UNSW research project on the evolution of identical skills in different species, have evolved to perform elaborate head bob and push up displays, and rapidly extend and retract their dewlap (throat fan) in visually 'noisy' environments.

Interestingly, the lizards occupy the same range of rainforest and grassland habitats, and face similar communication challenges in these environments. The study found that these lizards have evolved the same strategy to cope with the same selection problems. They adjust the speed or the length of time they spend displaying the movements according to the prevailing conditions.

The striking similarities in communication strategies for maintaining effective communication in noisy conditions have evolved independently in these lizards, as well as in other animal groups that have evolved separately for hundreds of millions of years. This scenario of two unrelated lizards displaying similar behaviour shows that natural selection directs evolution towards the same common set of adaptive outcomes.

The study emphasizes that these adaptations solve the challenges faced by animals in terms of evolutionary adaptation. It is a testament to the power of natural selection in shaping the behaviour and communication strategies of diverse animal species. The findings could pave the way for a better understanding of convergent evolution, a phenomenon where similar adaptations originate independently in unrelated species.