Gradient in pine bark bug, Aradus cinnamomeus, densities with distance from the industrial complex (*) at Harjavalta, Finland. White circles = 0-0.50 bugs 100 cm-2, light brown circles = 0.51-1.75 bugs 100 cm-2, brown circles = 1.76-3.50 bugs 100 cm-2, and purple circles = 3.51-12.2 bugs 100 cm-2. From Heliovaara and Vaisanen (1986) by permission from Blackwell Wissenschafts-Verlag GmbH.

environmental conditions change. Two general types of spatial variation are represented by the expansion of growing populations and by the discontinuous pattern of fragmented populations, or metapopulations.

Was this article helpful?

0 0

Post a comment