Back in 2014, collaborators Panayiotis Pafilis, Anthony Herrel, Johannes Foufopoulos and I initiated a multi-island lizard introduction experiment, inspired by the foundational anole evolutionary ecology work of Losos, Schoener, and Spiller. Our twist: we were going to do it in Greece, with a different genus of lizard – Podarcis. Wall lizards haven’t radiated like anoles, but there is fascinating work demonstrating rapid evolution in the genus and a large descriptive literature documenting the phenotypic differences of populations living on mainland, large islands, and small islands.

We introduced 20 marked individuals from the large, predator-rich island of Naxos to each of five Podarcis-free islets, and revisited the populations annually (up until pandemic), censusing each island. Each year we gathered new morphology, performance, behavior, and diet data, and released the lizards back to the experimental islets. We’ve just published a new paper showing that the traits that best predicted initial survival were not all the ones we’d expected. Body condition – sure – lizards with a higher body condition probably have the reserves that enable them to weather the stressful introduction. Bite force? Not so much. We’d expected bite force to be an important predictor of survival because lizards with harder bites would be more competitively dominant and also have access to defended prey items like gastropods. Contrary to our expectation, bite force was not a predictor of survival (but stay tuned, bite force has become more and more important as the experiment has continued).

If you’re interested, I’ve written lots more about the experiment on my blog over the years. We also have photos and videos from the islets:

Finally, a quick call to the community: I have six years of tissue samples from the five islet populations, but don’t have the molecular chops to ask any of the fantastically interesting questions we might be able to with paired survival, phenotype, and molecular data. If you’re interested in a collaboration, let me know!

 

New Literature Alert:

Colin M Donihue, Anthony Herrel, Johannes Foufopoulos, Panayiotis Pafilis, Body condition and jumping predict initial survival in a replicated island introduction experiment, Biological Journal of the Linnean Society, 2022;, blab172, https://doi.org/10.1093/biolinnean/blab172

 

Abstract: Over-water dispersal to small islets is an important eco-evolutionary process. Most often, new arrivals on islets find the environment harsh or mate-less, making their footholds on these islets fleeting. Occasionally, introduced animals are able to survive the strong selection following their arrival, leading to subsequent propagation and, in several famous cases, adaptive radiation. What traits predict that initial survival? We established a replicated island introduction experiment to investigate this process in lizards. In 2014, we introduced 20 Podarcis erhardii lizards to each of five small islets in the Greek Cyclades Islands. We found that the lizards that survived were those with better initial body condition, longer distal portions of their limbs and a greater propensity for jumping. Contrary to our expectations, neither body size nor the strength of the lizards’ bite – two traits positively related to competitive ability, which becomes important later in the colonization process in lizards – predicted survival. This is the first selection study of its kind investigating an experimental introduction of Podarcis, and whether the traits that determined initial survival are important in driving the future evolutionary trajectories of these populations remains to be determined.

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