Different population responses to climate change along a gradient of life history strategies


Winners and Losers? Not all species respond in the same way.

 

The population responses to sea ice among species can be contrasted because species have different life strategies (i.e. different investments in growth, reproduction, and survival). For example, the population of emperor penguins is more sensitive to decreases in sea ice conditions than the population of snow petrels. Emperor penguins breed almost annually and their adult survival decreases during years with low sea ice conditions. On the contrary, petrels skip reproduction during years with low sea ice conditions rather than compromising their survival and future opportunities to reproduce (Jenouvrier et al. 2005).


The population responses to sea ice can be also contrasted because species use different habitat.  For example, sea ice conditions positively affect the emperor penguin population but negatively affect the adélie penguin population. Indeed, these species are dependent on different aspects of the sea ice environment. During winter, emperor penguins need fast ice (i.e. sea ice locked to the coast, islets or grounded icebergs and motionless) to breed and nearby polynyas (i.e. areas of ice-free waters within sea ice cover) to feed, whereas adélie penguins nest on ice-free and snow-free land during summer and need persistent but divergent pack ice to feed (Ainley et al. 2011).


To provide general insights into the population responses to future climate change, my goal is to address two fundamental comparisons:

  1. (1)among species that show contrasted life history strategies (e.g. petrels versus penguins) and

  2. (2)among species that use different habitats (e.g. adélie penguin versus emperor penguin).