Conservation

Biology A2 · Classification, biodiversity and conservation. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.

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The idea

A species becomes extinct when its last individual dies. The main causes today are climate change, competition (often from introduced species), hunting by humans, and the damage and loss of habitats. Small populations are in most danger because they have little genetic diversity and cannot adapt.

We need to keep biodiversity for many reasons: stable ecosystems, services such as pollination and clean water, new medicines, useful alleles in the wild relatives of crops, and moral and aesthetic reasons.

Conservation can protect species where they live, in national parks and marine parks. It can also protect them elsewhere, in zoos, botanic gardens, seed banks and frozen zoos, sometimes with assisted reproduction.

Rules to remember

Conserved areas protect the whole ecosystem and keep the species in its natural habitat.
Zoos: captive breeding that avoids inbreeding, research, education and release to the wild.
Seed banks: seeds are dried and kept cold so they stay alive for many years. Frozen zoos: gametes, embryos and tissue are stored in liquid nitrogen.
IVF: eggs are fertilised by sperm in a dish outside the body.
Embryo transfer: embryos are placed in surrogate mothers, often of a related common species, so one rare female can have many young.
Invasive alien species have no natural predators or diseases in the new area; they out-compete, eat or infect native species.
IUCN assesses the extinction risk of species and publishes the Red List. CITES controls international trade in endangered species and their products.

Common mistake

Students mix up IUCN and CITES. IUCN assesses and lists how threatened a species is; CITES is the agreement that regulates trade.

Worked example

A seed bank is collecting seeds of a rare wild plant. Why should it collect a few seeds from many plants in several populations, and not many seeds from one plant?

Seeds from one plant carry only the alleles of that plant and of the few plants that pollinated it.
Different plants and different populations carry different alleles.
A wide sample therefore stores much more of the genetic diversity of the species.
Plants grown from it later are more likely to adapt to disease or a changing climate.

Answer: Sampling many plants and populations keeps as many alleles of the species as possible.

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