Despite the importance of the colonisation phase for invasion success, few early-stage introductions have been characterised and studied from the earliest stages following their initial importation. This thesis attempts to redress this information gap, using molecular techniques and common garden experiments to reconstruct colonisation history, reveal genetic diversity and demonstrate evolutionary potential in two recent introductions of Caribbean Anolis. Both of these colonisations provide useful models because they are examples of recent anthropogenic introductions on isolated land masses which contain congeneric native competitors. The colonisations studied in this thesis are the introduction of the Puerto Rican Anolis cristatellus to Dominica around 1998-2000, and of the Cuban native A. sagrei in St. Vincent around 2003.
Bayesian phylogenetic analysis of mtDNA sequence data was used to approximate the geographical origin of the introduced populations (A. cristatellus from north central Puerto Rico, and A. sagrei from Florida). Multiple mitochondrial haplotypes were present in Dominica, suggesting that at least seven reproductive females were present in the founding propagule, whilst in St. Vincent only a single haplotype was present. These approximate estimates of propagule size were used to evaluate the potential impact of demographic bottlenecks on genetic diversity and establishment success within introduced populations. Microsatellite analyses (using F-statistics and Bayesian methods) of the genetic diversity within and between native, source and introduced populations of A. cristatellus provided limited evidence for a genetic founder effect in Dominica. A replicated common garden experiment indicated that the variation in phenotypic characters amongst A. cristatellus populations at different altitudes on Dominica was predominantly genetically based, supporting the hypothesis that the introduced population is rapidly responding to novel environmental selection pressures.
The findings of the study are discussed in relation to the differing establishment success of the two colonisations, and are related to the wider context of colonisation theory and management practice.