A reversal of fortunes: climate change ‘winners’ and ‘losers’ in Antarctic Peninsula penguins

Climate change is a major threat to global biodiversity. Antarctic ecosystems are no exception. Investigating
past species responses to climatic events can distinguish natural from anthropogenic impacts. Climate
change produces ‘winners’, species that benefit from these events and ‘losers’, species that decline or become
extinct. Using molecular techniques, we assess the demographic history and population structure of
Pygoscelis penguins in the Scotia Arc related to climate warming after the Last Glacial Maximum (LGM). All
three pygoscelid penguins responded positively to post-LGM warming by expanding from glacial refugia,
with those breeding at higher latitudes expanding most. Northern (Pygoscelis papua papua) and Southern
(Pygoscelis papua ellsworthii) gentoo sub-species likely diverged during the LGM. Comparing historical
responses with the literature on current trends, we see Southern gentoo penguins are responding to current
warming as they did during post-LGM warming, expanding their range southwards. Conversely, Ade´lie and
chinstrap penguins are experiencing a ‘reversal of fortunes’ as they are now declining in the Antarctic
Peninsula, the opposite of their response to post-LGM warming. This suggests current climate warming has
decoupled historic population responses in the Antarctic Peninsula, favoring generalist gentoo penguins as
climate change ‘winners’, while Ade´lie and chinstrap penguins have become climate change ‘losers’.