Correlated Population Genetic Structure in a Three-Tiered Host-Parasite System: The Potential for Coevolution and...

Area of Science:

• Herpetology
• Evolutionary Biology
• Conservation Genetics

Background:

• Three subspecies of Northern Bahamian Rock Iguanas (Cyclura cychlura) are recognized, but genetic data challenges existing classifications within the Exuma Islands.
• Previous studies noted genetic distinctiveness between Andros Island and Exuma Island populations, but divergence within the Exumas is complex.

Purpose of the Study:

• To investigate the evolutionary relationships among Northern Bahamian Rock Iguana populations using a multi-tiered host-parasite system.
• To assess the validity of current subspecies designations for Cyclura cychlura in the Exuma Islands.
• To explore evidence for local adaptation and coevolutionary processes.

Main Methods:

• Comparative analysis of population relatedness across three tiers: Cyclura cychlura iguanas, their Amblyomma ticks, and Rickettsia spp. endosymbionts.
• Utilized molecular markers to examine genetic divergence and phylogenetic patterns within and between island populations.

Main Results:

• Cyclura cychlura cychlura on Andros Island is confirmed as a distinct evolutionary clade.
• Patterns of relatedness among Exuma Island populations (C. c. figginsi and C. c. inornata) are complex, suggesting evolutionary independence for C. c. inornata.
• Evidence supports two independent evolutionarily significant units within C. c. figginsi, indicating localized adaptation.

Conclusions:

• Coevolutionary relationships exist between the iguanas, their ticks, and Rickettsia spp., highlighting local adaptation.
• Relying solely on neutral molecular markers from a single taxon may be insufficient for recognizing evolutionary novelty in endangered species.
• The findings suggest a revision of subspecies boundaries may be warranted for Northern Bahamian Rock Iguanas.