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2021Topic 3
BIODIVERSITY AND CONSERVATION
IVÁN DEZA
CBA |
, 1
3.1 Biodiversity and conservation – Introduction
Biodiversity is a broad concept that encompasses the total diversity of living systems, including
species diversity, habitat diversity and genetic diversity.
- Species diversity:
o The variety of species per unit area, and measures the number of
species(richness)and their relative abundance (regularity).
o Greater species diversity makes ecosystems more resilient. Indicates stability
and maturity. Low diversity may indicate altered places.
o Tropical forests or corals have a lot of biodiversity, the tundra little.
o The Simpson Diversity Index
- Genetic diversity:
o It consists of the range of distinct genes found in a species or population. Each
individual has slightly different genes, very similar to those in their population.
Two different populations have even more different genes.
o Greater genetic diversity confers resistance to diseases and sudden changes in
the environment.
o Species with few populations (gray seals, e.g.) have little genetic diversity.
Species with many populations in different habitats (humans or red fox, e.g.)
have great genetic diversity.
- Habitat diversity:
o Generated when in an ecosystem we find many different habitats, with a great
variety of ecological niches.
A conservation of habitats generates an increase in the other types of diversity.
3.2 Origins of biodiversity
Biodiversity comes from evolution: there are so many different species with different genes due
to evolution from common ancestors.
Process of evolution through natural selection:
1. In a population of one species there is genetic diversity. Some individuals contain
different genes that will benefit, harm, or not affect them.
2. Due to natural variation and habitat diversity, some individuals will be better adapted
than others.
3. The more adapted have an advantage, and more likely to survive and reproduce.
4. The descendants of the most adapted individuals can inherit the genes that give the
advantage.
If a population is isolated, the differences generated by this process will gradually end up being
another species (speciation process). Separations normally occur by physical separations:
organisms cannot reproduce with those of the other population and therefore their genes are
not exchanged between populations.
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