Genetics and Demography in Biological Conservation by Russel Lande
Science Vol. 241:1455-1460
Lande argues that many conservation planners have erroneously spent their time focused
on the genetics of rare species while neglecting the importance of demography.
Pop. genetics: Inbreeding depression can be bad, but it isn’t necessarily the end of the
species. Rapidly it can be an issue, but gradually, evolution can takes it course and weed
out the bad alleles. Genetic variation in populations is important, but shouldn’t be
reduced to a magic #s such as Ne = 500. Establishing a minimum viable population size
based solely upon genetics is flawed b/c: the goal of preserving maximum genetic
variability within populations is based upon the assumption that the rate of evolution in a
changing in environment is limited by the amount of genetic variation (this assumption
has been rejected in favor of ecological opportunity as the primary rate-controlling factor
at least in morphological evolution, i.e. props to natural selection); little evidence that
heterozygosity increases fitness; sometimes too much variation from an optimum
phenotype can be detrimental. Extinction is fundamentally a demographic process
influenced by genetic and environmental factors.
Demography: Allee effect-Population numbers may drop to a level below which the
population can no-longer function for non-genetic reasons, such as group defense or
foraging. Stochastic demography-Given environmental and demography stochasticity
the best way to account for density-dependent age-structured populations is using
exstensive computer modeling. Patch-size-a population’s ability to surive near the edge
and the potential to lose individuals to an unsuitable habitat must be considered. Local
extinction and colonization-Some species naturally exist in divided populations for
social reasons or due to their naturally patchy habitat. Classical demography can be
combined with habitat occupancy by identifying the individual territory as the spatial
unit. There is an extinction threshold related to the amount of available habitat that is
suitable to support a population
Both the spotted owl and the red-cockaded woodpecker were managed based upon a
minimum viable population size designed to guarantee genetic viability and in the mean
time their habitats were fragmented and their numbers declined. The management
policies have since been changed to account for the demography of each species.
Russell Lande is cool! He has a beard and works at UC-San Diego (I bet he surfs or does extreme
sports too.) He works on quantitative genetics and evolutionary theory and yet still manages to
conduct research on ecology and conservation biology. Basically, he’s the total package when it
comes to organismal biology. He’s really smart and does stuff with models that only Todd would
understand. Lande has many many-cited publications in Ecology, Evolution, Science and
journals with two-word names like American Naturalist and Conservation Biology. When I grow
up I want to be just like Russell Lande. 
Russell Lande received his Ph. D. from Harvard University. He is past
President of the Society for the Study of Evolution, member of the American
Academy of Arts & Sciences, and a MacArthur Foundation Fellow.
Note: Russell Lande does not endorse this document.