Kiwi Taxonomy (1 Viewer)

[albertonykus]

Bemmels, J.B., O. Haddrath, R.M. Colbourne, H.A. Robertson, and J.T. Weir (2022)
Legacy of supervolcanic eruptions on population genetic structure of brown kiwi
Current Biology (advance online publication)
doi: 10.1016/j.cub.2022.05.064

Supervolcanoes are volcanoes capable of mega-colossal eruptions that emit more than 1,000 km^3 of ash and other particles. The earth’s most recent mega-colossal eruption was the Oruanui eruption of the Taupo supervolcano 25,580 years before present (YBP) on the central North Island of New Zealand. This eruption blanketed major swaths of the North Island in thick layers of ash and igneous rock, devastating habitats and likely causing widespread population extinctions. An additional devastating super-colossal eruption (>100 km^3) of the Taupo supervolcano occurred approximately 1,690 YBP. The impacts of such massive but ephemeral natural disasters on contemporary population genetic structure remain underexplored. Here, we combined data for 4,951 SNPs with spatially explicit demographic and coalescent models within an approximate Bayesian computation framework to test the drivers of genetic structure in brown kiwi (Apteryx mantelli). Our results strongly support the importance of eruptions of the Taupo supervolcano in restructuring pre-existing geographic patterns of population differentiation and genetic diversity. Range shifts due to climatic oscillations—a frequent explanation for genetic structure—are insufficient to fully explain the empirical data. Meanwhile, recent range contraction and fragmentation due to historically documented anthropogenic habitat alteration adds no explanatory power to our models. Our results support a major role for cycles of destruction and post-volcanic recolonization in restructuring the population genomic landscape of brown kiwi and highlight how ancient and ephemeral mega-disasters may leave a lasting legacy on patterns of intraspecific genetic variation.

 

[albertonykus]

Westbury, M.V., B. De Cahsan, L.D. Shepherd, R.N. Holdaway, D.A. Duchene, and E.D. Lorenzen (2022)
Genomic insights into the evolutionary relationships and demographic history of kiwi
PLoS ONE 17: e0266430
doi: 10.1371/journal.pone.0266430

Kiwi are a unique and emblematic group of birds endemic to New Zealand. Deep-time evolutionary relationships among the five extant kiwi species have been difficult to resolve, in part due to the absence of pre-Quaternary fossils to inform speciation events. Here, we utilise single representative nuclear genomes of all five extant kiwi species (great spotted kiwi, little spotted kiwi, Okarito brown kiwi, North Island brown kiwi, and southern brown kiwi) and investigate their evolutionary histories with phylogenomic, genetic diversity, and deep-time (past million years) demographic analyses. We uncover relatively low levels of gene-tree phylogenetic discordance across the genomes, suggesting clear distinction between species. However, we also find indications of post-divergence gene flow, concordant with recent reports of interspecific hybrids. The four species for which unbiased levels of genetic diversity could be calculated, due to the availability of reference assemblies (all species except the southern brown kiwi), show relatively low levels of genetic diversity, which we suggest reflects a combination of older environmental as well as more recent anthropogenic influence. In addition, we suggest hypotheses regarding the impact of known past environmental events, such as volcanic eruptions and glacial periods, on the similarities and differences observed in the demographic histories of the five kiwi species over the past million years.