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.kiwi | Apteryx | New Zealand | glaciation | diversification P leistocene climate cycles resulted in glaciation and the buildup of extensive ice sheets at temperate latitudes during periods of global cooling, followed by recession of ice sheets during brief interglacial periods. These cycles were originally proposed to have fragmented populations, resulting in speciation and the formation of much of today's species richness (1-5).

Pleistocene glacial cycles drive isolation, gene flow and speciation in the high‐elevation Andes

“…While a role for Late Pleistocene glacial cycles in species diversification has long been suggested (Haffer, ; Simpson, ), the impacts of Pleistocene glacial cycles in different environments seems highly variable (Haffer, ; Hewitt, ; Klicka & Zink, ; Rull, ; Weir et al ., ). Diversification caused by Pleistocene sea‐level fluctuations on oceanic island archipelagos appear to be mainly associated with infraspecific divergence (Papadopoulou & Knowles, ,b).…”

Extraction of DNA from captive‐sourced feces and molted feathers provides a novel method for conservation management of New Zealand kiwi (Apteryxspp.)

“…Kiwi are nocturnal, flightless, burrowing birds that are now confined to remote areas of New Zealand, making them difficult to study (see (Germano et al., in press; Weir, Haddrath, Robertson, Colbourne, & Baker, ) for detailed maps of contemporary kiwi distributions). Currently available monitoring tools for kiwi include call counts, radio telemetry, and surveys using detection dogs (McLennan et al., ; Pierce & Westbrooke, ; Robertson & de Monchy, ; Robertson & Fraser, ).…”

“…To capture current genetic variation across kiwi, as well as assign individuals to parental populations where necessary, the marker panel must distinguish between the major lineages recently described in Weir et al. (). To be noninvasive, the panel must be amplifiable from samples such as feces and shed feathers (see Figure ), while avoiding frequent genotyping errors, that is, allelic dropout (ADO) and false alleles, found in low‐template DNA samples (Broquet et al., ).…”

The importance of recognising and conserving biological diversity: a reply to Dussex et al. (2018)

“…Weston et al 2015;Grosser et al 2016;Weir et al 2016) not be dismissed as an 'inconvenient truth'. It is particularly concerning to us that Dussex et al (2018) seem to imply that agnostic ("cautious") approaches (whereby newly-recognised, highly-distinct lineages are not afforded separate taxonomic status, e.g.…”

“…It is particularly concerning to us that Dussex et al (2018) seem to imply that agnostic ("cautious") approaches (whereby newly-recognised, highly-distinct lineages are not afforded separate taxonomic status, e.g. Weston et al 2015;Weir et al 2016) are somehow preferable to studies that make more definitive taxonomic and conservation recommendations. Rather than representing a genuinely progressive view, the "caution" advocated by Dussex et al (2018) carries the real risk that important biodiversity could become extinct before it is prioritised for conservation (e.g.…”