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Intl. J. of Mol. Ecol. and Conserv. 2012, Vol. 2, No.1, 1-7
http://ijmec.sophiapublisher.com
1
A Report Open Access
Are Genetic Threats a Serious Concern in the Conservation of Natural Populations?
Tawanda Tarakini
1,2
, Xingxing Liang
1
1. Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT
2. Department of Wildlife and Safari Management, Chinhoyi University of Technology, Bag 7724 Chinhoyi, Zimbabwe.
Corresponding author email:
tawandatizora@gmail.com
Authors
International Journal of Molecular Ecology and Conservation, 2012, Vol.2, No.1 doi: 10.5376/ijmec.2012.02.0001
Received: 23 March, 2012
Accepted: 7 May, 2012
Published: 11 June, 2012
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Tarakini and Liang, 2012, Are genetic threats a serious concern in the conservation of natural populations? International Journal of Molecular Ecology and
Conservation, Vol.2, No.1 (doi: 10.5376/ijmec.2012.02.0001)
Abstract
The earth is currently faced with a mounting loss of species that is threatening biodiversity and genetic threats are among
the causes of this challenge. However, the contribution of genetic threats to the extinction crisis is of current debate. In this paper,
we present our arguments in light of loss of genetic variability, inbreeding depression, Accumulation of mildly deleterious mutations,
local extinction in the presents of migration and extinction in metapopulations context. The extinction processes often operates across
many facets hence the division between demographic, environmental and genetic just artificial. In addition, genetic threats only
become important after populations have been driven to very low levels, particularly by human activities such as poaching, habitat
fragmentation, introduction of invasive organisms and pollution. We advocate for conservation efforts to be distributed proportionally
to threats posed by any factor, and as shown by most studies, most genetic threats are currently not priorities for many species.
Keywords
Inbreeding; Genetic variation; Mutation; Extinction; Meltdown theory; Major histocompatibility complex (MHC)
Genetic threats, among other factors such as
human-induced habitat loss, pollution, alien invasion
and overexploitation are threatening persistence of
natural populations. However the relative importance
of genetic threats in conservation is a subject of
current debate. Loss of genetic variability,
accumulation of mildly deleterious mutations and
inbreeding depression has been identified as the major
threats to natural populations (Gaggiotti, 2003); their
effects are more pronounced in small, isolated and
rapidly declining populations (Caro and Laurenson,
1994). They reduce survivorship, fecundity and mean
population fitness which all tend to drive populations
to extinction. Genetic threats can be short-term on
individual viability and fecundity (have a direct effect
on population demographics, potentially making it
more susceptible to extinction) or long term (effects
on the population’s response to environmental
changes) that might lead to extinction as well (Amos
and Balmford, 2001). In this essay, the level of threats
posed by genetic factors (genetic variability,
inbreeding and accumulation of mildly deleterious
mutations) to conservation will be discussed under the
context of isolated populations, local populations with
immigrations and metapopulations.
1 Loss of genetic variability
Genetic variation allows adaptation by populations to
environmental changes, re-establishment after local
extinction and range expansion but such abilities
might be lost in the absents of migrations, mutations
or selection favoring heterozygotes (Gaggiotti, 2003).
Stochastic changes in gene frequencies (due to
mendelian segregation and family sizes variations)
may lead to random genetic drift in small populations
resulting in reduced population` s ability to respond to
future environmental changes and evolution (Caro and
Laurenson, 1994). Genetic drift eliminates low
frequency alleles very rapidly when populations are
small or declining. This is detrimental for survival of
populations in the long-term but there are few cases
that clearly demonstrate that genetic drift is an
imminent extinction threat (Gaggiotti, 2003). A well
documented case of genetic drift is for the Mauritius
kestrel (
Falco punctatus
), where the population was
reduced to a single pair in the 1950s and it recovered