ena-STUDY-Swedish museum of Natural HIstory-07-08-2019-16:33:43:665-294
Complete genomes of two extinct New Zealand passerines show responses to climate fluctuations but no evidence for genetic erosion prior to extinction
Human  intervention,  pre-human  climate  change  (or  a  combination  of  both),  as  well  as  genetic effects,  contribute  to  species  extinctions.  While  many  species  from  oceanic  islands  have  gone extinct  due  to  direct  human  impacts,  the  effects  of pre-human  climate  change  and  human settlement on the genomic diversity of insular species and the role that loss of genomic diversity played in their extinctions remains largely unexplored.  To address this question, we sequenced whole genomes of two extinct New Zealand passerines, the huia (Heteralocha acutirostris) and South Island kokako (Callaeas cinereus). Both species showed similar demographic trajectories throughout the Pleistocene. However, the South Island kokako continued to decline after the last glaciation,  while  the  huia  experienced  some  recovery.  Moreover, there  was  no  indication  of inbreeding resulting from recent mating among closely-related individuals in either species. This latter result indicates that population fragmentation associated with forest clearing by Maori may not have been strong enough to lead to an increase in inbreeding and exposure to genomic erosion. While genomic  erosion  may  not  have  directly  contributed  to  their  extinctions,  further  habitat fragmentation  and  the  introduction  of  mammalian  predators by  Europeans may  have  been  an important driver of extinction in huia and South Island kokako.
Human  intervention,  pre-human  climate  change  (or  a  combination  of  both),  as  well  as  genetic effects,  contribute  to  species  extinctions.  While  many  species  from  oceanic  islands  have  gone extinct  due  to  direct  human  impacts,  the  effects  of pre-human  climate  change  and  human settlement on the genomic diversity of insular species and the role that loss of genomic diversity played in their extinctions remains largely unexplored.  To address this question, we sequenced whole genomes of two extinct New Zealand passerines, the huia (Heteralocha acutirostris) and South Island kokako (Callaeas cinereus). Both species showed similar demographic trajectories throughout the Pleistocene. However, the South Island kokako continued to decline after the last glaciation,  while  the  huia  experienced  some  recovery.  Moreover, there  was  no  indication  of inbreeding resulting from recent mating among closely-related individuals in either species. This latter result indicates that population fragmentation associated with forest clearing by Maori may not have been strong enough to lead to an increase in inbreeding and exposure to genomic erosion. While genomic  erosion  may  not  have  directly  contributed  to  their  extinctions,  further  habitat fragmentation  and  the  introduction  of  mammalian  predators by  Europeans may  have  been  an important driver of extinction in huia and South Island kokako.