Changes in Abundance and Distribution of Humboldt Penguin Spheniscus Humboldti

At an intraspecific level, patterns of species abundance distribution (SAD) vary in space and time, especially over the largest scales. The most basic, unimodal pattern is expressed in a log-normal shape, based on the abundant-center hypothesis (Gaston et al. 2008). SAD patterns can be driven by environmental variables (e.g. temperature, salinity, precipitation, productivity) as well as intrinsic, species-specific factors (e.g. physiology, dispersal ability and other life-history attributes). Climate change and oscillations (e.g. El Niño, La Niña) are important variables known to influence SAD of marine species both historically and recently. Thus, when faced with climate change, a population, and ultimately a species, may have three possible biological responses: range shift, adaptation or extirpation (Holt 1990).