title: Explosive ice age diversification of kiwi.
abstract: Molecular dating largely overturned the paradigm that global cooling during recent Pleistocene glacial cycles resulted in a burst of species diversification although some evidence exists that speciation was commonly promoted in habitats near the expanding and retracting ice sheets. Here, we used a genome-wide dataset of more than half a million base pairs of DNA to test for a glacially induced burst of diversification in kiwi, an avian family distributed within several hundred kilometers of the expanding and retracting glaciers of the Southern Alps of New Zealand. By sampling across the geographic range of the five kiwi species, we discovered many cryptic lineages, bringing the total number of kiwi taxa that currently exist to 11 and the number that existed just before human arrival to 16 or 17. We found that 80% of kiwi diversification events date to the major glacial advances of the Middle and Late Pleistocene. During this period, New Zealand was repeatedly fragmented by glaciers into a series of refugia, with the tiny geographic ranges of many kiwi lineages currently distributed in areas adjacent to these refugia. Estimates of effective population size through time show a dramatic bottleneck during the last glacial cycle in all but one kiwi lineage, as expected if kiwi were isolated in glacially induced refugia. Our results support a fivefold increase in diversification rates during key glacial periods, comparable with levels observed in classic adaptive radiations, and confirm that at least some lineages distributed near glaciated regions underwent rapid ice age diversification.
authors: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada M1C 1A4; jason.weir@utoronto.ca.
authors: Jason T
authors: JT
authors: Weir
authors: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; Department of Natural History, Royal Ontario Museum, Toronto, ON, Canada M5S 2C6;
authors: Oliver
authors: O
authors: Haddrath
authors: Science & Policy Group, Department of Conservation, Wellington, New Zealand.
authors: Hugh A
authors: HA
authors: Robertson
authors: Science & Policy Group, Department of Conservation, Wellington, New Zealand.
authors: Rogan M
authors: RM
authors: Colbourne
authors: Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada M5S 3B2; Department of Natural History, Royal Ontario Museum, Toronto, ON, Canada M5S 2C6;
authors: Allan J
authors: AJ
authors: Baker
mesh_terms: D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics*; D017753:Ecosystem; D019143:Evolution, Molecular; D049810:Genetic Speciation; D006801:Humans; D046448:Ice Cover; D009520:New Zealand; D046108:Palaeognathae / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial
keywords: Apteryx; New Zealand; diversification; glaciation; kiwi