Global biogeography of geckos (Squamata: Gekkota) reveals Old-World origins and region-specific heterogeneity in diversification
This study presents the most comprehensive phylogenetic analysis of geckos to date, revealing an Old-World origin with African roots for major families, identifying Africa as a biodiversity refugia and Eurasia as a diversification hotspot, and demonstrating that despite surviving the K-Pg extinction, the lineage experienced no mass extinction events while exhibiting region-specific heterogeneity in diversification rates.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of a preprint that has not been peer-reviewed. It is not medical advice. Do not make health decisions based on this content. Read full disclaimer
To understand the story of life on Earth, scientists often look at how groups of animals spread across the globe and how they multiply into new species over millions of years. This field, known as macroevolution, tries to figure out why some places are bursting with life while others are relatively empty, and how the history of our planet's continents and climates has shaped the living world. One of the most successful groups of animals to navigate this history is the gecko. These small, often nocturnal lizards are found on almost every continent, from the tropics to temperate zones, and they have evolved a remarkable ability to stick to surfaces and survive in dry conditions. Because they are so widespread and diverse, geckos offer a perfect window into how a single group of animals can conquer the world. The big questions researchers ask are simple but profound: Where did geckos originally come from? Did they spread by drifting on floating islands or by walking across land bridges? And have they survived major disasters in Earth's history, like the asteroid impact that wiped out the dinosaurs, without losing their momentum?
A new study by Yuanxing Liao and Phillip L. Skipwith tackles these questions by building the most complete family tree of geckos ever created. The researchers gathered genetic data from 1,783 different species, representing about 70 percent of all known geckos, to create a massive map of their relationships. They combined this with fossil evidence to estimate when different groups split apart and where they lived at those times. By analyzing this tree, they could trace the movement of geckos across the globe and measure how fast different groups were evolving into new species. The goal was to see if the speed of their evolution was the same everywhere or if certain regions acted as engines of diversity while others served as safe havens.
The study reveals that geckos are an ancient lineage, with their earliest ancestors appearing during the Jurassic period, long before the dinosaurs died out. The researchers found that the modern geckos we see today likely originated in the Old World, specifically in the regions that make up Africa and Eurasia. This finding challenges some older ideas that suggested geckos might have started in the southern continents of Gondwana. The data shows that while the ancestors of the entire group were widespread, the specific families that make up most of today's diversity—such as the common house geckos and their relatives—likely began their journey in Africa. From there, they spread out, with some groups crossing oceans to reach the Americas and others moving across land to populate Asia and Australia.
One of the most striking discoveries is that geckos did not experience a massive die-off during the Cretaceous-Paleogene extinction event, the catastrophe that ended the age of dinosaurs. Despite surviving this global upheaval and the dramatic climate shifts that followed, the study found no evidence that geckos suffered a sudden, widespread loss of species. Instead, they continued to diversify steadily. This resilience suggests that geckos were able to weather these ancient storms without their evolutionary engine stalling, allowing them to emerge as one of the most successful lizard groups on the planet.
The researchers also uncovered that geckos do not evolve at the same speed everywhere. The study identified a clear split in how different groups diversified. The geckos found in Australia and nearby islands, known as pygopodoids, have evolved at a relatively steady and slower pace. In contrast, the geckos found across the rest of the world, known as gekkonoids, have experienced much faster and more varied rates of evolution. Within this global group, certain regions acted as hotspots for creating new species. Eurasia, particularly parts of Asia, emerged as a major center where new species were generated rapidly. Africa, on the other hand, seems to have acted as a refuge, a place where many ancient lineages survived and accumulated over time without necessarily exploding into new species as quickly as their cousins in Asia.
The study also highlighted the unique role of Africa in the gecko story. While it was the likely starting point for several major families, it also served as a source for multiple journeys to the New World. The data suggests that geckos crossed the Atlantic Ocean from Africa to the Americas on at least five separate occasions, likely riding on floating vegetation or drifting on currents. This ability to cross vast oceans is a key part of their success, allowing them to colonize islands and distant continents. The researchers found that the physical distance between landmasses and their relative positions played a huge role in where geckos could go, with ocean currents and wind patterns likely guiding their passive travel.
Ultimately, this research paints a picture of a lineage that is both ancient and remarkably adaptable. Geckos did not just survive the major crises of Earth's past; they thrived in the wake of them. Their history is one of a slow, steady origin in the Old World, followed by a series of daring dispersals that took them to every corner of the globe. While some groups remained in their home regions and diversified slowly, others seized opportunities to spread across oceans and continents, evolving at a frantic pace in places like Asia. The study confirms that the diversity of geckos we see today is the result of a complex interplay between where they started, how they moved, and how different regions of the world either protected them or pushed them to evolve faster. It is a story of survival, movement, and the quiet, persistent power of life to find a way forward, even after the world has changed beneath its feet.
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