IslandParadox - Unraveling the Paradox of Genetic Diversity in Isolated Oceanic Lineages

Some of the most diverse lineages on our planet are found on islands. Yet, islands are often remote and isolated, and insular species have small population sizes that make natural selection less effective and lead to higher extinction rates. This creates a paradox: how can we observe such rich biodiversity on islands if the conditions seem unfavorable for diversification? In this project, we aim to explore this question by sequencing the genomes of daisies (family Asteraceae) in the Galápagos. We will focus on three lineages native to the Galápagos: Darwiniothamnus, Lecocarpus, and Scalesia. By analyzing genetic data, we hope to uncover how changes in population size, speciation, colonization of new environments, and population growth have contributed to diversification. We will also identify the genomic features associated with diversification, focusing on the evolution of structural variants, and pangenome-variation.

This proposal will study how isolated lineages generate and maintain genetic diversity. Three replicate radiations of the sunflower family on the Galápagos Islands – Scalesia, Lecocarpus and Darwiniothamnus will be investigated. Despite the constraints imposed by founder events, small population sizes, and inbreeding, these radiations exhibit remarkable ecological and phenotypic diversity, prompting the question: how do isolated lineages generate and maintain genetic diversity? Understanding the mechanisms of genetic diversity generation and maintenance is crucial for predicting the ability of species to recover from human-induced population declines. Habitat fragmentation, habitat destruction, and climate change are rapidly diminishing species diversity worldwide, making it imperative to identify the factors that contribute to the recovery of genetic variation. In this context, insular lineages can serve as model systems as their outstanding diversity arises following a founder event. The findings of this research will directly inform conservation efforts by collaboration with the GalápagosVerde2050 project. Our research will employ molecular and bioinformatic methods. This includes the ancestral recombination graph to determine the age of genetic variation of different genomic regions, comparing empirical to simulated data, and assessing the role of structural variants and pangenomes in local adaptation. We aim to produce three high-impact manuscripts that offer insights into the generation and maintenance of genetic diversity.