4.3 Small Population Paradigm and Genetic Bottlenecks
3 min read•july 30, 2024
Small populations face unique challenges in conservation biology. Demographic and environmental factors, along with genetic risks like drift and inbreeding, make these groups vulnerable to extinction. Understanding these issues is crucial for developing effective conservation strategies.
Genetic bottlenecks, where population size sharply decreases, can have long-lasting effects on a species' survival. By studying these events and implementing targeted management techniques, conservationists can help small populations maintain genetic diversity and increase their chances of long-term viability.
Challenges of Small Populations
Demographic and Environmental Vulnerabilities
Top images from around the web for Demographic and Environmental Vulnerabilities
The Extinction Vortex – Molecular Ecology & Evolution: An Introduction View original
Is this image relevant?
Frontiers | Habitat Fragmentation Increases Overall Richness, but Not of Habitat-Dependent Species View original
Is this image relevant?
Spatiotemporal patterns and ecological consequences of a fragmented landscape created by damming ... View original
Is this image relevant?
The Extinction Vortex – Molecular Ecology & Evolution: An Introduction View original
Is this image relevant?
Frontiers | Habitat Fragmentation Increases Overall Richness, but Not of Habitat-Dependent Species View original
Is this image relevant?
1 of 3
Top images from around the web for Demographic and Environmental Vulnerabilities
The Extinction Vortex – Molecular Ecology & Evolution: An Introduction View original
Is this image relevant?
Frontiers | Habitat Fragmentation Increases Overall Richness, but Not of Habitat-Dependent Species View original
Is this image relevant?
Spatiotemporal patterns and ecological consequences of a fragmented landscape created by damming ... View original
Is this image relevant?
The Extinction Vortex – Molecular Ecology & Evolution: An Introduction View original
Is this image relevant?
Frontiers | Habitat Fragmentation Increases Overall Richness, but Not of Habitat-Dependent Species View original
Is this image relevant?
1 of 3
increases susceptibility of small populations to random fluctuations in birth rates, death rates, and sex ratios
(natural disasters, climate fluctuations) disproportionately affects small populations
Allee effects decrease population growth rate at low population densities creating additional challenges
in fragmented habitats increase predation and competition pressures on small populations
Genetic Risks
causes random changes in allele frequencies with stronger impact on small populations
Potentially leads to loss of beneficial alleles
Reduces overall genetic diversity
establishes new populations with small number of individuals
Results in reduced genetic variation
Increases genetic homogeneity
Genetic Consequences of Small Populations
Inbreeding and Genetic Load
occurs when related individuals mate
Increases
Expresses deleterious recessive alleles
accumulates more rapidly in small populations
Reduces population fitness due to presence of deleterious alleles
Higher risk of extinction due to loss of adaptive potential from reduced genetic diversity
Population Genetics Dynamics
Genetic drift causes rapid loss of genetic diversity and fixation of alleles in small populations
(Ne) often much smaller than census population size
Exacerbates genetic issues in seemingly larger populations
Small populations experience higher rates of:
changes
Loss of rare alleles
Reduction in
Genetic Bottlenecks and Population Viability
Bottleneck Characteristics and Effects
sharp reduction in population size resulting in significant loss of genetic diversity
Severity and duration of bottleneck influence:
Extent of genetic diversity loss
Population's ability to recover
Post-bottleneck populations exhibit:
Reduced fitness
Decreased adaptability
Lower resistance to diseases
Bottleneck events can lead to founder effect if population recovers
Reduced genetic diversity persists in subsequent generations
Detection and Analysis
Genetic bottlenecks detected through molecular techniques:
Analysis of allelic diversity
Measurement of heterozygosity levels
Examination of genetic markers (microsatellites, SNPs)
Concept of population bottleneck closely related to (MVP) size in conservation biology
Long-term genetic consequences assessed through:
Computer simulations
(PVA)
Management Strategies for Small Populations
Genetic Management Techniques
introduces unrelated individuals from other populations
Increases genetic diversity
Reduces inbreeding depression
Ex situ conservation programs maintain genetic diversity
Captive breeding serves as safeguard against extinction