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New species and extinction Fig 25.14 New species and extinction

Biodiversity- number of species within an area Fig 56.3 Genetic Diversity Biodiversity- number of species within an area Ecosystem Diversity

If a species loses genetic diversity, it can go extinct Fig 56.11

Fig 56.10 Extinction vortex

Resources are not evenly distributed Fig 55.6 Resources are not evenly distributed

Biodiversity- number of species within an area Fig 56.3 Genetic Diversity Biodiversity- number of species within an area Ecosystem Diversity

Larger areas can support more biodiversity Fig 54.28 Islands

Larger areas can support more biodiversity Fig 54.26 # bird species

Water is critical for biodiversity Fig 54.25

New species can have an affect throughout the ecosystem Fig 54.16

Interactions include area, climate, competition...

Increased numbers of one species can reduce the population of other species

Competition limits where species can live Fig 54.3 Competition limits where species can live

niche- the specific environment where a species lives Fig 54.3 niche- the specific environment where a species lives

Niche overlap leads to competition.

Prolonged direct competition is rare.

Prolonged direct competition is rare.

Where these species overlap, they do not compete. Fig 54.4 Where these species overlap, they do not compete.

Changes in Extinctions and Biodiversity

Have we overstated the tropical biodiversity crisis. William F Have we overstated the tropical biodiversity crisis? William F. Laurance Trends in Ecology & Evolution Vol. 22: 65-70 February 2007

Are we on the verge of a massive die-off of tropical species?

Increased rural density leads to decreased forest.

The good news? About 21–24% of species in the Asian tropics and 16–35% of species in the African tropics are threatened with possible extinction.

Rural populations are expected to decline.

Substantial areas of agricultural land are likely to be abandoned. This could enable significant forest regeneration, which could help buffer species losses from deforestation.

Not all habitats are equal Fig 56.13 Not all habitats are equal

A third to a half of all old-growth species avoid younger (<30-year-old) regrowth.

Technology means that more resources can be extracted by fewer people.

Rural populations are expected to decline, but increased urban population will demand more resources.

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