SG: The demographic and life-history consequences of re-colonizing secondary habitats

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Tropical forests are one of the most diverse and complex ecosystems on earth. They are also one of the most productive systems for conversion to agriculture, leading to large scale deforestation and local extinction of wildlife that once lived in those forests. While tropical deforestation for agricultural uses is still common, social and economic forces are shifting attention to manufacturing jobs in cities and resulting in abandonment of agricultural areas. As a result, forests are starting to re-grow and expand through a process called succession. The re-growing forests, called "secondary" forests, are different from the original forests; they have smaller trees and less canopy cover. Eventually, the wildlife that were lost with deforestation will re-colonize these secondary forests. This project will examine how wildlife find and live in secondary forests. The investigators will focus on small lizards and test ideas about which individuals are able to thrive in the forests and why they are able to do so. Results will be important for management of both forests and wildlife, as both change under human influences. Range expansion theory provides a testable framework to study the ecological, genetics and evolutionary mechanisms driving the recolonization of secondary habitats by wildlife species. This theory makes four fundamental predictions: A recolonizing population will (1) be composed highly dispersive individuals, (2) experience higher population growth rates, (3) experience escape and release from natural enemies, and (4) have lower genetic diversity when compared to the source population. The study follows an interdisciplinary approach that combines an observational study, a field experiment, demographic modeling and genomic analyses to test these predictions in Anolis gundlachi, a shaded-forest-specialist lizard re-colonizing secondary forests following large-scale forest recovery in Puerto Rico. We understand the general patterns of re-colonization showing that secondary forests of 20 years can hold up to 92% of old-growth forest species. This study will advance the field through a robust multi-scale evaluation of the processes and mechanisms driving the evolution of life-history traits during secondary forest re-colonization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.