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(A)
(B)
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Pajek
Pajek
Pajek
Fig. 14.6.
Examples of spatial networks. (A): Spatial location of more than 3000 ponds
in Donana National Park (Spain). Below, schematic representation of a subset of ponds
showing links from dry (white circles) to ooded (black circles) ponds mediated by the
maximum dispersal distances of an amphibian species. (B): The mating network of a
Prunus mahaleb population. Nodes represent trees and arrows indicate pollination events
mediated by insects. (C): The bipartite roosting network of a bird-predator bat. On the
left, nodes represent individual bats. On the right, nodes represent individual trees. A
link between a bat and a tree indicates that that particular bat used the particular tree.
(Adapted from Fortuna et al. (2006, 2008a,b).)
are critical for landscape connectivity and hence population persistence [Urban and
Keitt (2001); Minor and Urban (2008)].
There are a few key examples of how the spatial dynamics resulting from indi-
vidual movements between habitat sites shapes the structure of a spatial network
of patches. Fortuna et al. (2006) showed that the structure of a large network of
temporary ponds | used as breeding sites by several amphibian species | changes
with increasing levels of drought (Fig. 14.6A). When drought was very intense and
the number of dry ponds increased, only a few ooded ponds were accessible from
a high number of dry ones. In this way, a ranking of ponds was established as a
function of their connections to dry ponds, constrained by the dispersal abilities of
species. In similar systems, such as riverine networks, the fragmentation over time
of network of populations of a sh species was investigated and used to propose
mechanisms for ecologically successful restoration [Schick and Lindley (2007)].
The ecological and evolutionary processes shaping the spatial distribution of ge-
netic variability include natural selection, genetic drift, mutation, non-random mat-
ing, and gene ow by migration, to name a few. The cessation of gene movement
because of limited dispersal or assortative mating results in genetic isolation and
