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Biodiversity and Evolution

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Kathie Ang

on 9 September 2018

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Transcript of Biodiversity and Evolution

Biodiversity and Evolution
Is the key to sustaining life on the planet

Four types of biodiversity
species diversity
genetic diversity
ecosystem diversity (biomes)
functional diversity (processes)

10-14 million species on Earth (exact number unknown)
Biological Diversity
caused by
The process by which changes in genes over time resulted in new species
Remember that populations evolve, not individuals (changes in gene frequency)
Natural selection is a mechanism of evolution
survival and reproduction based on those most fit in a particular environment
Occurs because of:
genetic variation in a population
mutations in gametes (egg/sperm)
differential survival (adaptations) in a specific environment
differential reproduction
There are no "goals" of evolution
Earth's History
Geologic events affected evolution of species
location and movement of continents (different environments) resulted in different adaptations
climate change
catastrophes (meteors, volcanic activity)
Factors Affecting Biodiversity
New species arise through speciation, via:
geographic isolation: physically separated
reproductive isolation: gametes don't fuse
such that they cannot produce viable, fertile offspring anymore
biological extinction vs. local extinction
endemic species: only found in one area, especially vulnerable to biological extinction
background extinction vs. mass extinction
Importance of Diversity
Species richness vs. species evenness
The higher the species richness, the more stable, sustainable, and productive the ecosystem
better respond to stress

Role of Species
The role that a species plays in its ecosystem
generalist: broad niche (live in different places, eat different foods)
better in changing conditions
specialist: narrow niche
better in stable conditions
Five Major Roles
Native species: normally live and thrive in an ecosystem
Nonnative species: migrate or introduced into an ecosystem
can be beneficial (crops, livestock)
can be harmful by out-competing native species because of lack of predators/disease
Indicator species: provide early warnings of damage to an ecosystem (fragmentation, chemical pesticides, pollution, climate change)
birds, butterflies, amphibians
Keystone species: have a large effect on the types and abundance of other species in an ecosystem. Often limited in numbers but their effect is large.
pollinators (butterflies, bees, bats), top predators
Foundation species: create/enhance environment that benefits other species
beavers, elephants, birds and bats with reforestation
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