Genetic variation in native and translocated populations of the laysan finch [telespiza cantans)

Abstract

Population size reductions are usually expected to result in decreases of within-population genetic variation. We here report on allozyme variation in (1) the endemic population of the Laysan finch (Telespiza cantans) that was reduced by a major population crash during the early 1900s and (2) translocated populations on three islets of a distant atoll (Pearl & Hermes Reef). These populations resulted from the introduction of 108 birds to one islet in 1967 and subsequent dispersal to the other islets. Variation in 33 allozyme loci on Laysan was found to be lower than the average in avian populations, matching theoretical expectation. Unexpectedly, the average heterozygosity of Pearl & Hermes populations is higher than at Laysan, and significantly so for two of five polymorphic loci. Variation in allele frequencies is relatively high for avian populations (FST= 0.049), both among the islets of P&H, and between P&H and Laysan. This suggests that isolation within the tiny, translocated populations has resulted in a significant level of genetic differentiation during a relatively short time period (less than 20 years). © 1991 The Genetical Society of Great Britain.