Studied by 6 people
biodiversity
The diversity of life forms in an
environment
levels of biodiversity
Biodiversity exists
at three scales.
(a) Ecosystem diversity is the variety of
ecosystems within a region.
(b) Species diversity is the variety of
species within an ecosystem.
(c) Genetic diversity is the variety of
genes among individuals of a
species.
Figure 2.1
habitat diversity
variety of habitats that exist in a given ecosystem
specialists
organisms that live only under a narrow range of biotic
or abiotic conditions
• Ex. Koala can only eat eucalyptus leaves
generalists
organisms that can live under a wide range of biotic and
abiotic conditions
• Ex. White tailed deer can live in a wide range of climates in both
North and South America, feed on a variety of plants
species richness
The total number of species in a given area.
• A higher richness usually means that the ecosystem is in good health
species evenness
The relative proportion of individuals within the
different species in a given area.
ecosystem services
The processes by which life-supporting
resources such as clean water, timber, fisheries, and agricultural
crops are produced.
There are 5 categories of ecosystem services:
• Provisions
• Regulating services
• Support systems
• Resilience and cultural services
provision
A good that humans can use directly.
• Examples of provisions include lumber, food crops, medicinal plants,
natural rubber, and furs.
• Of the top 150 prescription drugs sold in the United States, about 70
percent come from natural sources.
regulating services
Regulating Services
• Natural ecosystems help to regulate environmental conditions.
• Natural ecosystems, such as tropical rainforests and oceans, remove
carbon from the atmosphere.
• Ecosystems also are important in regulating nutrient and hydrologic
cycles.
support services
Natural ecosystems provide numerous support services such as
pollination of food crops.
• Ecosystems also provide natural pest control services because they
provide habitat for predators that prey on agricultural pests.
• A healthy ecosystem can filter harmful pathogens and chemicals from water
cultural sevices
The awe-inspiring beauty of nature has
instrumental value because it provides an aesthetic benefit for which
people are willing to pay.
• Similarly, scientific funding agencies may award grants to scientists for research that explores biodiversity with no promise of any economic gain.
Hlppco
threats to biodiversity
threats to biodiversity
H- habitat loss
l- exotic species
p-pollution
p-increase in human population
c- climate change
o-over- harvesting
Island bio-geography
A theory that demonstrates the dual
importance of habitat size and distance in determining species
richness.
Island bio-geography
Larger islands support more total species – the larger the island
the greater the biodiversity
• Species richness increases as the size of the habitat increases.
• Islands closer to the mainland support more species
• Easier to colonize areas closer to mainland
ecological tolerance
refers to the range of conditions such as
temperature, salinity, flow rate, and sunlight an organism can endure
before injury or death results
• Can apply to individuals and species
ecological tolerance
Optimal range – range where organisms survive, grow and
reproduce
• Zone of Physiological Stress – range where organisms survive, but
experience some stress such as infertility, lack of growth,
decreased activity
• Zone of Intolerance – range where organism will die
ecological tolerancw
Fundamental niche The suite of abiotic conditions under which a
species can survive, grow, and reproduce.
• Realized niche The range of abiotic and biotic conditions under
which a species actually lives.
micro-evolution
Evolution below the species level
macroevolution
Evolution that gives rise to new species, genera,
families, classes, or phyla.
gene flow
The process by which individuals move from one population to
another and thereby alter the genetic composition of both populations.
• The arrival of individuals from adjacent populations alters the frequency of
alleles in the population.
• In a population that is experiencing natural or artificial selection, high gene flow
from outside can prevent the population from responding to selection.
• Gene flow can be helpful in bringing in genetic variation to a population that lacks it.
gene drift
A change in the genetic composition of a population
over time as a result of random mating.
bottleneck effect
A reduction in the genetic diversity of a
population caused by a reduction in its size
founder effect
A change in the genetic composition of a population as a
result of descending from a small number of colonizing individuals
Allopatric speciation
speciation that occurs with geographic
isolation
• When a group of individuals goes to a new area that is physically
separated from the larger population
• If the conditions are different enough evolution will occur and a new
species will occur
Sympatric speciation
Sympatric speciation – evolution of one species into two species
without any geographic isolation
• Usually occurs due to polyploidy – having three or more sets of
chromosomes
• Humans have altered plant species for larger plants and fruits, found
in some snails and salamanders
primary succession
Ecological succession occurring on surfaces that
are bare rock with no soil.
• Pioneer species such as algae, lichens and mosses will commonly move into
unoccupied habitat
secondary succession
The succession of plant life that occurs in areas
that have been disturbed but have not lost their soil.
succession in lakes
Over a time-span of hundreds to
thousands of years, lakes are filled with
sediments and slowly become terrestrial
habitats.
keystone species
species whose activities have a particularly
significant role in determining community structure. sea otter, lion, gray wolf, sea star, elephant
indicator species
plant or animal that by its presence, abundance,
scarcity or chemical composition demonstrates some distinctive
aspect of the character or quality of an ecosystem that is present. amphibians, fish, grizzly bears, prairie dogs
ecosystem engineer
A keystone species that creates or maintains
habitat for other species.
pioneer species
lichens, fungi, bacteria, lyme grass
