BIOL 1500 Chapter Notes - Chapter 15: Background Extinction Rate, Ecological Pyramid, Habitat Fragmentation

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March 15th, 2016. BIOL1500 Unit 9-Chapter 15 (335-361)
Conserving Biodiversity
15.1 The Sixth Extinction
oThe endangered species act was passed in 1973 to protect and encourage the
population growth of threatened and endangered species, at high risk of extinction
passed due to erosion of biodiversity
oMeasuring Extinction Rates: based on fossil records, not a smooth increase in
biodiversity over time. Species losses that are at a global scale, affect large
numbers of species and are dramatic in impact (mass extinctions) Can say the
largest were caused by climate fluctuations that altered land forms, continental
drift or an asteroid impact event. One must know background extinction rate
which is the rate at which species are lost through evolutionary processes.
oCauses of extinction: Habitat destruction and fragmentation: agricultural,
industrial, residential development accelerated as population rapidly increased of
humans. The general pattern in area species curves are that number of species in
an area increases as the size increases but but the rate of increase slows as as the
area becomes too large. Rainforests will be decreased to about 10% in the next 30
years greatly affecting the populations living within. Habitat fragmentation occurs
and is threatening to larger predators such as bears, they follow basic rules of
biological systems: energy flows in one direction within an ecological system
along a good chain, which typically runs from the sun to producers
(photosynthesis organisms), to primary consumers that feed on them, to secondary
consumers (feed on primary) and so on. Most calories taken at one trophic level
are respired to support individuals at that level (most is dissipated as heat) The
flow of energy along a food chain leads to trophic pyramid, relationship between
biomass (total weight) of populations at each level of chain. Habitat destruction
can cause lower levels of pyramid to shrink affecting top predators of calories.
Introduced species: organisms brought by human activity to a new environment,
often dangerous to native species. The process of co-evolution occurs when pairs
of species adapt to each other via natural selection. Competition of resources.
Overexploitation: human use of a species outpaces the reproduction rate. This
will affect economic activity as well. Also present due to hunting practices.
Pollution is the release of poisons, excess nutrients and other waste into the
environment. Increased nutrients can increase production of algae which produce
toxins that accumulate in small animals and poison their consumers.
Eutrophication threatens waterways.
15.2 The Consequences of Extinction
oLoss of Resources: Economic deficits, wild species contain cells that can assist
with disease prevention, by preserving domesticated crops, scientists can find
resources to reduce pest damage.
oPredation: most species are beneficial to humans by being a part of our biological
community, consisting of all organisms living in a certain area. Each species
occupies an ecological niche (job/role of species) The complex array of niches is
usually called a food web. A species that survives by eating another is a predator.
oMutualism, how bees feed the world: interaction of 2 species that benefits each
other. One benefits, the other is unaffected. Bees are primary pollinators of
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