Comparison of adult census size and effective population size support the need for continued protection of two Solomon Island endemics

Because a population’s ability to respond to rapid change is dictated by standing genetic variation, we can better predict a population’s long-term viability by estimating and then comparing adult census size (N) and effective population size (Ne). However, most studies only measure N or Ne, which can be misleading. Using a combination of field and genomic sequence data, we here estimate and compare N and Ne in two range-restricted endemics of the Solomon Islands. Two Zosterops White-eye species inhabit the small island of Kolombangara, with a high elevation species endemic to the island (Z. murphyi) and a low elevation species endemic to the Solomon Islands (Z. kulambangrae). Field observations reveal large values of N for both species with Z. kulambangrae numbering at 114,781 ± 32,233 adults, and Z. murphyi numbering at 64,412 ± 15,324 adults. In contrast, genomic analyses reveal that Ne was much lower than N, with Z. kulambangrae estimated at 694.5 and Z. murphyi at 796.1 individuals...