Conservation (4.16)

Maintaining genetic diversity increases a species’ ability to survive environmental change.

Higher genetic diversity means:

• More alleles in the population.
• A greater chance some individuals possess advantageous alleles.
• Reduced risk of inbreeding depression.
• Greater long-term evolutionary potential.

Small isolated populations lose diversity through genetic drift and inbreeding, increasing extinction risk.

Captive breeding programmes (CBPs) aim to increase population sizes of critically endangered species while carefully managing their gene pools.

CBP programmes involve:

• Global electronic databases (studbooks) to track genetic lineages.
• Animals or frozen gametes are regularly exchanged between international institutions to maximise outbreeding and maintain high genetic diversity.

Challenges include that small captive populations suffer from genetic drift and inbreeding depression, which expose harmful homozygous recessive alleles. This can result in disease outbreaks and reduced genetic variation.

Reintroduction involves releasing captive-bred individuals back into their native historical habitats where wild populations have collapsed.

Success requires first eliminating the original threats that drove the species to extinction (e.g., poaching, habitat loss).

Animals are often acclimatised in protective enclosures in the wild, receiving supplementary food before final release.

Captive animals sometimes struggle to forage or avoid predators, requiring intensive pre-release training. Without this, or if unsuccessful, there can be a high mortality rate after release.

Zoos serve as vital hubs for ex situ conservation science:

• Research – scientists study animal reproductive physiology, behavioural ecology, and nutritional needs in captivity. This generates data impossible to gather in the wild, directly optimising in situ field conservation strategies.
• Education – zoos educate millions of visitors annually. Public exhibits build political, social, and financial support for global biodiversity conservation, transforming visitor awareness into conservation funding.

Seed banks preserve plant genetic diversity by storing seeds in induced dormancy.

1. Collection: seeds are collected from wild populations to capture genetic variation.
2. Drying: low humidity removes water, preventing microbial growth and reducing freezing damage.
3. Cold storage: low temperatures reduce respiration and metabolism, extending seed lifespan.
4. Viability testing: samples are germinated periodically to check survival.
5. Regeneration: if viability falls, seeds are grown and fresh seeds are collected.

Benefits of seed banks:

• Conserves many species in limited space.
• Preserves genetic diversity and rare alleles.
• Provides material for research and reintroduction programmes.
• Protects against extinction events.

Limitations of seed banks:

• Not all plants produce seeds suitable for storage.
• Stored populations may not represent all genetic variation present in a species.
• Seeds may lose viability over time.
• Does not protect habitats or ecosystems.