Did interaction between human pressure and Little Ice Age drive biological turnover in New Zealand?

Abstract

Aim To test for simultaneous Holocene biogeographic turnover events in the New Zealand region. Specifically, we synthesize ancient DNA, radiocarbon data and archaeological data to assess the chronologies of late Holocene lineage extinction and replacement. Location Cool‐temperate coastal ecosystems of New Zealand and the subantarctic. Methods We present new ancient DNA and radiocarbon data for New Zealand sea lions, and synthesize existing climatic, genetic and archaeological data, to test for synchronous megafaunal extinction and replacement events. The collated data include ancient DNA sequences from over 200 ancient sea lion and penguin specimens, in addition to 150 modern genetic samples. Results Our temporal genetic analyses show that, following human‐driven extinction events, synchronous marine megafaunal replacement events occurred at around 1500 AD, coinciding with the Little Ice Age onset and an associated drastic human demographic decline in southern New Zealand. Conclusions A combination of climatic and human demographic shifts likely facilitated northward expansion of subantarctic sea lion and penguin lineages, replacing extirpated mainland New Zealand marine megafauna. Broadly, the interaction between human pressure and late Holocene climatic change may explain multiple biological turnover events in the Southern Hemisphere.

Ancient DNA and morphometric analysis reveal extinction and replacement of New Zealand's unique black swans

“…The extinct lineages were subsequently replaced by Australian C. atratus ( figure 3). This newly characterized 'turnover' event highlights that extinction can potentially facilitate major phylogeographic shifts, and parallels similar extinction-colonization events in costal and marine megafauna [25][26][27]29,32]. Anthropogenic impact and predation by introduced mammals no doubt caused the rapid extinction of C. sumnerensis-indeed, the presence of Cygnus remains in archaeological midden deposits attests to their use as food [24].…”

“…New Zealand's rich archaeological record [24] presents intriguing opportunities to unravel the often complex dynamics between human populations and indigenous wildlife [25][26][27][28][29][30][31]. Recent analyses of ancient DNA (aDNA) have led to paradigmatic shifts in our understanding of the evolution of NZ's biota [32]. In particular, genetic studies of prehistoric remains have revealed a number of 'cryptic' biological turnover events, highlighting the role of density-dependent processes constraining lineage distributions [33] and leading to reappraisals of which lineages are truly 'native' [17].…”

How disturbance and dispersal influence intraspecific structure

“…Additionally, the importance of disturbance in facilitating such structure (e.g. lineages expanding from remnant patches: Davies, Cary, Landguth, Lindenmayer, & Banks, 2016), or by allowing opportunistic lineage turnover (Waters, Fraser, Maxwell, & Rawlence, 2017) has only recently begun to be explored.…”

History Repeats: Large Scale Synchronous Biological Turnover in Avifauna From the Plio-Pleistocene and Late Holocene of New Zealand

“…Many New Zealand plants and animals, once considered ancient, have been shown to be more recent transoceanic immigrants arriving long after the separation of Zealandia from eastern Gondwana (e.g., Knapp et al, 2005;Mitchell et al, 2014). The oceans surrounding the New Zealand archipelago are a permeable barrier (e.g., McCulloch et al, 2017) and, while the focus has been on species mobility, establishment and persistence of immigrants is just as important (Boessenkool et al, 2009;Collins et al, 2014;Rawlence et al, 2015Rawlence et al, , 2017aGrosser et al, 2016;Waters and Grosser, 2016;Waters et al, 2017).…”