Galimberti,F. & Fabiani,A. & Sanvito,S. 2001. Opportunity for selection
in southern elephant seals (Mirounga leonina): the effect of spatial
scale of analysis. Journal of Zoology London. In press.

Abstract
The opportunity for selection, I, calculated as the variance in
relative fitness, sets an upper limit to the amount of adaptive change
that selection may produce. Therefore, it is a potentially valuable, and
frequently used, measure of the potential of action of phenotypic
selection. Although many different aspects of I calculation and analysis
have been explored, the effect of spatial scale chosen for calculation
received little attention, notwithstanding the mounting evidence that
natural populations are not homogeneous and present a hierarchical
spatial structure. In this paper, we examine the effect of scale on
estimation of I from data collected in two populations of southern
elephant seals (Mirounga leonina), an easy observable and strongly
polygynous species. We found a significant effect of spatial scale on
three important aspects of I calculation and analysis: dependence of I
on mean fitness, between population variation of I, and effect of local
demography on I.