Application of genetic techniques to conservation of the Critically Endangered Grenada Dove Leptotila wellsi

Abstract

The Grenada Dove Leptotila wellsi is a Critically Endangered species endemic to the island of Grenada. It exists in two geographically isolated populations across the island. As an endemic on a small island with a limited and decreasing population, this species is at risk from genetic deterioration. Particular risks include inbreeding depression and accelerated loss of genetic diversity resulting from ongoing habitat fragmentation and population isolation. The work reported in this thesis aimed to provide the first genetic data for the Grenada Dove, assess its genetic status and determine what conservation management recommendations can be made to help ensure its long-term survival. A systematic literature review revealed geographical bias in how genetic approaches have been applied to the conservation of island bird species, under-representation of threatened species and highlighted a gap between genetic research and active conservation management. A protocol for obtaining usable genetic material from moulted plumulaceous feather samples was developed and showed that samples collected non-invasively in the field, that were kept in non-optimal conditions for deoxyribonucleic acid (DNA) extraction, can be used effectively to sequence informative regions of mitochondrial DNA (mtDNA) for genetic analysis. The evolutionary and life history of the Grenada Dove were investigated by estimating its phylogenetic placement and using phylogenetic comparative methods for estimating unknown life history traits. The Grey-Chested Dove Leptotila cassinii was identified as the species with which the Grenada Dove shares the most recent common ancestor, with an estimated divergence of approximately 2.53 million years ago. Life history trait values were predicted for the Grenada Dove and suggest this species will be slow to recover after a major population decline. The mitochondrial genetic diversity of Grenada Dove populations was assessed for the two areas of occupancy. Two haplotypes were identified with one haplotype unique to the population in the West. Selective neutrality tests Fu’s Fs=0.78 and Tajima’s D=0.83 were positive and not significant, with an FST value = 0.71 suggesting a marked genetic divergence between the two populations. This study showed low mitochondrial genetic diversity, a non-expanding population and iii | iii clear evidence for genetically isolated populations. Population viability analysis (PVA) was used to evaluate extinction risk and the potential for conservation management for the two populations of the Grenada Dove. This PVA identified that loss of forest habitat to commercial development is likely to have the biggest impact on extant populations and that conservation management to increase productivity is likely be the most effective conservation strategy. This thesis contributes novel information regarding evolutionary history, life history, population genetics and future population trajectories to inform long-term conservation actions for the Critically Endangered Grenada Dove.