The “paradox of the great speciators” has puzzled evolutionary biologists, requiring excellent dispersal ability to explain wide distributions, but reduced dispersal abilities to explain high numbers of divergent, isolated forms. Rapidly changing dispersal abilities are assumed, but identifying a mechanism has proved elusive. We take a novel approach by examining genetic changes at four “migration” genes in a great speciatior, Zosterops lateralis.
Genotypic data at four candidate loci from 320 Zosterops lateralis individuals from 21 populations of varying migratory capabilities in Australia and New Zealand (and associated islands), New Caledonia and Vanuatu. Seven neutral genetic microsatellite loci were used to assess neutral genetic variation, and to provide inferences of gene flow among populations. Using linear mixed models, we assessed if allele length variation was significantly associated with migratory ability.
Gene flow estimates inferred that high levels of migration occurred among Australasian populations, particularly Tasmania and New Zealand. Allelic polymorphisms were observed in ADCYAP and CREB1, with CREB1 showing a pattern of longer mean allele length in Australasia/New Zealand populations, but shorter in New Caledonia and Vanuatu populations. Linear mixed models did not show any significant association of mean CREB1 or ADCYAP allele length with inferred gene flow.
The four migration-linked candidate genes do not appear to be associated with migratory ability in the silvereye. This work presents a first look into the genetic mechanisms behind the loss of migratory ability in silvereyes with the next step involving the analysis of genome-by-sequencing SNP data.
Marsden Fund no: UOO1410