Genetic Variability and Population Differentiation Inferred From Dna Fingerprinting in Silvereyes (Aves: Zosteropidae)

Abstract

This study evaluated DNA fingerprinting as a tool for estimating population genetic diversity and differentiation by comparing minisatellite variation in island and mainland populations of silvereyes (Aves: Zosterops lateralis). Three populations with different recent histories were compared: (1) Heron Island and neighboring islands, colonized 3000 to 4000 yr ago; (2) Lady Elliot Island, colonized within the past two decades; and (3) an adjacent mainland population, which presumably has existed for thousands of years. The degree of genetic variability within the three populations reflected both their size and the time since their colonization. Minisatellite diversity was highest in the mainland population, intermediate in the Capricorn Island group (which was shown to represent a single admixture), and lowest in the Lady Elliot Island population, possibly because of a recent population bottleneck during colonization. Mean band sharing between any two populations was less than the mean within either of those populations, and four fingerprint bands common to island birds were rare or absent in the fingerprints of mainland birds. In the absence of significant gene flow between the mainland and the islands, the populations have apparently become distinct at minisatellite loci, as evidenced by differences in both allelic diversity and in the frequencies of specific fragments. Within the Heron Island population, cohort analyses demonstrated the temporal stability of the fingerprint profile over 6 yr. This study demonstrates that length polymorphisms at minisatellite loci may be stable enough over time to retain information about recent historical and demographic effects on the relative genetic variability and differentiation of small, closely related populations.

Morphological Shifts in Island‐dwelling Birds: The Roles of Generalist Foraging and Niche Expansion

“…This part of the study was conducted on the Capricorn silvereye (Z. l. chlorocephalus) population on Heron Island, located 72 km off the eastern coast of Australia in the southern Great Barrier Reef (Mees 1969;Kikkawa 1973). This island race is largely restricted to Capricorn and Bunker group islands and is significantly larger (40% heavier, 26% thicker bill, 20% longer bill, 28% longer tarsus, 10% longer wing) than the mainland race (Z. l. familiaris), to which it is closely related (Mees 1969;Kikkawa 1970Kikkawa , 1976Degnan 1993;Clegg et al 2002a,b). The Heron Island population of silvereyes is individually color banded to allow easy identification (Kikkawa 1997).…”

Genetic and morphological differentiation between remnant populations of an endangered species: the case of the Seychelles White‐eye

“…It has also been applied successfully to studies of other small isolated island populations (Gilbert et al . 1990, Degnan 1993, Kappa 1998 with which the Seychelles White-eye can be directly compared.…”

“…Galapagos finches Geospiza sp. Lack 1968, Grant & Grant 1989; Australian Silvereyes, Zosterops lateralis Degnan 1993). Smaller body-sizes on Conception could be due to founder effects.…”

Microgeographic Patterns of Genetic and Morphological Variation in Savannah Sparrows (Passerculus sandwichensis)

“…Although the high variability associated with mini satellite loci allows genetic discrimination among geographically close populations (Degnan 1993; this study), DNA fingerprinting data are not ideal for studies of population structure.…”

“…Numerically, the band-sharing index Sjk is twice the number of bands shared between individuals j and k divided by the total number of bands scored in the two lanes. The population affiliations of j and k are arbitrary, and estimates of mean within-population similarity (e.g., SW ith in = S isl-is l) can be compared directly to estimates of mean between-population similarity (e.g., Sbetw = S isl-main ) ' Population subdivision is indicated when Swithin is greater than Sbetw (Degnan 1993 ).…”