Genetic consequences of a century of protection: serial founder events and survival of the little spotted kiwi (Apteryx owenii)

Abstract

We present the outcome of a century of post-bottleneck isolation of a long-lived species, the little spotted kiwi (Apteryx owenii, LSK) and demonstrate that profound genetic consequences can result from protecting few individuals in isolation. LSK were saved from extinction by translocation of five birds from South Island, New Zealand to Kapiti Island 100 years ago. The Kapiti population now numbers some 1200 birds and provides founders for new populations. We used 15 microsatellite loci to compare genetic variation among Kapiti LSK and the populations of Red Mercury, Tiritiri Matangi and Long Islands that were founded with birds from Kapiti. Two LSK native to D'Urville Island were also placed on Long Island. We found extremely low genetic variation and signatures of acute and recent genetic bottleneck effects in all four populations, indicating that LSK have survived multiple genetic bottlenecks. The Long Island population appears to have arisen from a single mating pair from Kapiti, suggesting there is no genetic contribution from D'Urville birds among extant LSK. The Ne/NC ratio of Kapiti Island LSK (0.03) is exceptionally low for terrestrial vertebrates and suggests that genetic diversity might still be eroding in this population, despite its large census size.

Keywords: Apteryx owenii; conservation; genetic bottleneck; kiwi; low Ne/NC; microsatellite.

Figure 1.

(a) Current distribution of extant LSK populations and (b) translocation history of those included in this study. LSK were once found throughout New Zealand but now comprise eight closed sanctuary populations (circles) that were founded via translocation of birds. Four extant populations (filled circles) are included in this study.

Figure 2.

Distribution of allelic frequencies within four populations at 15 microsatellite loci.

Figure 3.

Relationship between mean expected heterozygosity observed (H_E) and expected at mutation : drift equilibrium (H_EQ) at 15 microsatellite loci for four LSK populations. Line represents equality between H_E and H_EQ under a two-phase model of mutation.