Download Speciation, Extinction, and Biodiversity

G. Tyler Miller’s
Living in the Environment
13th Edition
Evolution and Biodiversity:
Origins, Niches, and Adaptations
Chapter 5
Kingdoms of Life
Algae, mold
Lack nucleus
Survive in oxygen free environment
Types of Evolution
Microevolution
Small genetic changes
- Genes mutate,
individuals selected,
populations evolve
- p. 101 peppered moth
Macroevolution
Longterm, large scale changes where
1.New species formed
2.Species lost due to extinction
Evolution and Adaptation
• Co-Evolution
– Populations of two different species interacting over a
long period of time
– Gene pools impact each other
• Predator-Prey Relationships
• Plant defense mechanisms
– Hippocampus Videos
Evolution and Adaptation
Natural selection
• Process in by which individuals of a population acquire
genetically based traits that increase their chances of
survival and their ability to produce offspring.
Adaptation (n.)
– A heritable trait that enables an organism to better
survive and reproduce under a given set of
environmental conditions
Artificial selection
• Humans select one or more desirable genetic traits in
the population of a plant or animal.
Natural Selection
Conditions necessary for natural
selection:
– variability
– heritability
– differential reproduction
Fig. 5-5 p. 101
Climate Change + Natural Selection
• Changes in climate throughout the earth’s history
have shifted where plants and animals can live.
Figure 4-6
Limits on Adaptation through
Natural Selection
• A population’s ability to adapt to new
environmental conditions through natural
selection is limited by its gene pool and how
fast it can reproduce.
– Humans have a relatively slow generation time
(decades) and output (# of young) versus some
other species.
Ecological Niches and Adaptation
Occupation
• Ecological niche
– functional role of a species in an
ecosystem.
Address
• Habitat
– Physical location of a species
Evolution is the driving force that leads to
perfect fit b/n organism & environment.
Ecological Niches
• Fundamental niche
– Full potential range of the
physical, chemical, and biological
factors a species can use if there
were no direct competition from
other species.
– Potential, idealized
• Realized niche
– Part of a species fundamental
niche that are actually used.
– Actual
Broad and Narrow Niches
• Generalist species
– Species with a broad ecological niche.
• Live in many different places.
• Eat a variety of food.
• Tolerate a wide range of environmental conditions, very
adaptable, tolerable
(flies, mice, deer, catfish, humans)
• Specialist species
– Species with a narrow ecological niche.
• Live only in one type of habitat
• Use only a few types of food
• Tolerate only a narrow range of climatic and are prone to
extinction, less resilient to change
(tiger salamander, red-cockaded woodpecker, spotted owls,
pandas)
Generalist and Specialist Species:
Broad and Narrow Niches
• Generalist
species
tolerate a
wide range of
conditions.
• Specialist
species can
only tolerate a
narrow range
of conditions.
Speciation, Extinction, and Biodiversity
Speciation - formation of two species
from one species because of
divergent natural selection
1) Geographic isolation – groups
of the same species become
physically separated
Geographic Isolation
…can lead to reproductive isolation, divergence
of gene pools and speciation.
Speciation, Extinction, and Biodiversity
2) Reproductive Isolation – isolated
populations become so genetically
different they cannot . . .
Interbreed, or
produce live, fertile offspring
Extinction: Lights Out
• Extinction occurs
when the
population
cannot adapt to
changing
environmental
conditions.
The
golden toad of Costa Rica’s
Monteverde cloud forest has
become extinct because of
changes in climate.
Figure 4-11
Extinction: Lights Out
• 99.9 % of all
species that
ever existed
are now
extinct
Figure 4-11
How do speciation and
extinction affect biodiversity?
Speciation – Extinction =
Biodiversity
Effects of Humans on Biodiversity
• The scientific consensus is that human activities
are decreasing the earth’s biodiversity.