Data from: Genetic status and timing of a weevil introduction to Santa Cruz Island, Galápagos

Successful invasive species can overcome or circumvent the potential
genetic loss caused by an introduction bottleneck through a rapid
population expansion and admixture from multiple introductions. We explore
the genetic makeup and the timing of a species introduction to Santa Cruz
Island in the Galápagos archipelago. We investigate the presence of
processes that can maintain genetic diversity in populations of the
broad-nosed weevil Galapaganus howdenae howdenae. Analyses of combined
genotypes for 8 microsatellite loci showed evidence of past population
size reductions through moment and likelihood-based estimators. No
evidence of admixture through multiple introductions was found, but
substantial current population sizes (N0 298, 95% HPD 50-2300), genetic
diversity comparable to long-established endemics (Mean number of
alleles=3.875) and lack of genetic structure across the introduced range
(ΦST = 0.01359) could suggest that foundations are in place for
populations to rapidly recover any loss of genetic variability. The time
estimates for the introduction into Santa Cruz support an accidental
transfer during the colonization period (1832-1959) pre-dating the spurt
in human population growth. Our evaluation of the genetic status of G. h.
howdenae suggests potential for population growth in addition to our field
observations of a concurrent expansion in range and feeding preferences
towards protected areas and endemic host plants.