Extinct New Zealand megafauna were not in decline before human colonization

Abstract

The extinction of New Zealand's moa (Aves: Dinornithiformes) followed the arrival of humans in the late 13th century and was the final event of the prehistoric Late Quaternary megafauna extinctions. Determining the state of the moa populations in the preextinction period is fundamental to understanding the causes of the event. We sampled 281 moa individuals and combined radiocarbon dating with ancient DNA analyses to help resolve the extinction debate and gain insights into moa biology. The samples, which were predominantly from the last 4,000 years preceding the extinction, represent four sympatric moa species excavated from five adjacent fossil deposits. We characterized the moa assemblage using mitochondrial DNA and nuclear microsatellite markers developed specifically for moa. Although genetic diversity differed significantly among the four species, we found that the millennia preceding the extinction were characterized by a remarkable degree of genetic stability in all species, with no loss of heterozygosity and no shifts in allele frequencies over time. The extinction event itself was too rapid to be manifested in the moa gene pools. Contradicting previous claims of a decline in moa before Polynesian settlement in New Zealand, our findings indicate that the populations were large and stable before suddenly disappearing. This interpretation is supported by approximate Bayesian computation analyses. Our analyses consolidate the disappearance of moa as the most rapid, human-facilitated megafauna extinction documented to date.

Ancient DNA microsatellite analyses of the extinct New Zealand giant moa (Dinornis robustus) identify relatives within a single fossil site

“…This N e was chosen based on opportunistic trial and error, as there is to our knowledge no way of analytically deriving the equilibrium theta under a generalised microsatellite mutation model (Fu and Chakraborty, 1998) such as that implemented in FASTSIMCOAL2. Note that these simulations were done using a constant-sized population at mutation-drift equilibrium, hence theta deviates slightly from that inferred in Allentoft et al (2014) where a flexible demographic model was used. We performed 100 replicates of this simulation and calculated r XY values as above.…”

“…The microsatellite, mtDNA, and radiocarbon age data analysed in this study were first presented in Allentoft et al (2014), where details of sampling, DNA extraction, genotyping validation and radiocarbon dating are given. The D. robustus data set includes mtDNA control region sequences from 87 radiocarbon dated individuals and multilocus microsatellite profiles from 74 of these.…”

“…A mtDNA control region sequence of 340 bp (excluding primers) was amplified from 87 individuals using two sets of overlapping primers (Bunce et al, 2003). The associated GenBank accession numbers for the individual mtDNA sequences are presented in Allentoft et al (2014). Six moa microsatellite markers were amplified successfully in 74 of the 87 individuals using rigorous methods for generating high-quality microsatellite data from ancient DNA as outlined previously (Allentoft et al, 2011).…”

“…However, with new methods available for identifying microsatellites markers from aDNA (Allentoft et al, 2009) and the development of strict protocols for the subsequent data generation (Taberlet et al, 1996;Allentoft et al, 2011), microsatellite analyses of extinct taxa are no longer beyond reach (Ishida et al, 2012;Nyström et al, 2012;Allentoft et al, 2014). Here we employ microsatellite DNA profiling on a large assemblage of radiocarbon-dated fossils of the extinct New Zealand moa (Aves: Dinornithiformes) in an attempt to gain new insights into the palaeobiology of this extinct megafauna.…”

“…They became extinct as a result of overhunting and habitat destruction shortly after Polynesians settled in the thirteenth century (Anderson, 1989;Holdaway and Jacomb, 2000;Allentoft et al, 2014;Holdaway et al, 2014). As is the case for most extinct taxa, little is known about their biology except some insights into their feeding habits, gained from their gut contents and genetic and morphological analyses of coprolites (e.g., Burrows et al, 1981;Burrows, 1989;Wood et al, 2008Wood et al, , 2013.…”