Biodiversity & Evolution, part 2
Miller & Spoolman, 16th ed
Big Idea #4
◊ Human activities decrease biodiversity
What is a “species”?
◊ A species is a group of the same type of
organism that can breed with each
other and produce fertil...
How do we get new species?
◊ Speciation - the formation of new
species
◊ Most common mode of speciation:
◊ Geographic isolation - members of a
population physically separated (due to
migration,...
◊ Geographic
isolation may lead
to reproductive
isolation - the two
groups can no
longer reproduce
or produce fertile
offs...
Reproductive isolation
◊ Takes a long time
• In fastest breeding organisms - 10s - 100s
of years
• In slower breeding orga...
Extinction is Forever :’(
◊ Extinction - an entire species ceases to
exist
http://aso.gov.au/titles/historical/tasmanian-t...
Who is vulnerable to extinction?
◊ Endemic species - found in only one place
◊ Resource specialist species - eat a limited...
Types of extinction
◊ Background
extinction - low rate
of species
extinction that
occurs all the time -
on average 1-5
spe...
◊ Mass extinction = significant rise in
extinction rate where large groups of
species are wiped out
◊ ~ 250 mya about 95% ...
Extinction and biodiversity
◊ When species go extinct, it opens new
habitat and resources for other species
- possibly lea...
Quick Think
◊ How would you respond to someone
that says that because extinction is a
natural process, we should not worry...
Big Idea #5
◊ Biodiversity increases the sustainability
to ecosystems
How do we measure species
diversity?
◊ 2 major components:
• Species richness - the
number of different
types of species
•...
Simple example
◊ High School A has
1000 students
• 350 white students
• 400 black students
• 250 Hispanic
students
◊ High ...
More “real”
example
◊ Tropical rain forest
• 10,000s of different
species, but low
numbers of each
type
◊ Deciduous
forest...
Where is it most diverse?
◊ It varies with the
geographic location
◊ On average, there are
more plants and animals
near th...
◊ Four MOST species rich environments:
• Tropical rain forests
• Coral reefs
• Ocean bottom
• Large tropical lakes
High species richness
◊ Areas that have high species richness
also have higher primary productivity
and tend to be more st...
Islands
◊ Theory of island biogeography - the
number of species on an island is
determined by 2 things: immigration
rate a...
2 Things about the island
affect these rates:
◊ 1. Size of the island
• Smaller islands have less species because
it is a ...
◊ Smaller islands also have higher
extinction rates
• Have fewer resources and less ecosystem
diversity
◊ 2. Distance from the mainland
• Closer to the mainland tends to have
higher immigration rate and thus more
species
This work is important because
◊ We create islands
when we develop land
◊ Scientists use this
theory to determine
how big ...
Quick Think
◊ If you could design a healthy,
sustainable ecosystem, but you had to
choose between high species richness
an...
Big Idea #6
◊ Each species plays an important role in
its ecosystem
Ecological Niche
◊ The role that a species plays in the
ecosystem
• It includes everything that affects its
survival and r...
Habitat
◊ Where a species lives
◊ (Niche is the WAY it lives)
2 main types of niches
◊ Generalists - broad niche
• Can live in many places
• Eats a variety of foods
• Can tolerate a ra...
◊ Specialists - narrow niche
• Only live in one type of habitat
• Use one or just a few food types
• Tolerate a small rang...
Pros and Cons of each type
◊ Generalist -
• More competition
• More adaptable to
change
◊ Specialist
• Little or no
compet...
5 especially important niches
◊ Native species
◊ Nonnative species
◊ Keystone species
◊ Indicator species
◊ Foundation spe...
Native species
◊ Species that normally live in a given
area
• They have evolved along with the other
native species and ha...
Nonnative species
◊ Aka alien, invasive, exotic
◊ Accidentally or deliberately introduced
◊ Not always bad - most crops and
livestock are nonnative species
◊ Sometimes they ARE bad - in 1957
Brazil introduced wil...
More on nonnative species
◊ Sometimes - an introduces species just
dies out
• The new area is not favorable to it
◊ Sometimes, the nonnative species
flourishes, but with no harm to other
organisms
• Habitat is favorable
• Native species...
◊ Sometimes - nonnative species takes
over
• Often there are no predators for this
species, since it hasn’t evolved alongs...
Indicator Species
◊ Provide ecologists with an early warning
system for damage to the ecosystem
◊ They are the canaries in...
Examples:
◊ Birds - found almost everywhere,
heavily affected by environmental
damage, especially chemical pesticides
Examples
◊ Amphibians - breathe partially through
skin, so very sensitive to changes in
water quality
Keystone species
◊ Have a large effect on the number and
type of other species in the ecosystem
Examples:
◊ Top predators - feed on and help
regulate the size of of other species
◊ Pollinators - control the size of pla...
Effects of losing a keystone
species
◊ When a keystone species is lost - it
leads to population crashes and
extinctions of...
Foundation Species
◊ Aka ecosystem engineers
◊ Play a major role in creating the
ecosystems in which they live
Examples:
◊ Elephants pull out or break small trees
in the African savannah
◊ This allows grass to grow and benefits
other...
Examples:
◊ Beavers - build dams to create ponds
that other species benefit from
Quick Think
◊ Should we devote more of our budget
to protecting keystone and foundation
species, perhaps at the peril of o...
APES Ch. 4, part 2
APES Ch. 4, part 2
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APES Ch. 4, part 2

  1. 1. Biodiversity & Evolution, part 2 Miller & Spoolman, 16th ed
  2. 2. Big Idea #4 ◊ Human activities decrease biodiversity
  3. 3. What is a “species”? ◊ A species is a group of the same type of organism that can breed with each other and produce fertile offspring.
  4. 4. How do we get new species? ◊ Speciation - the formation of new species
  5. 5. ◊ Most common mode of speciation: ◊ Geographic isolation - members of a population physically separated (due to migration, mountain range, road) - over time they may become separate species
  6. 6. ◊ Geographic isolation may lead to reproductive isolation - the two groups can no longer reproduce or produce fertile offspring ◊ When groups are reproductively isolated, they are different species ◊ Geographic isolation may lead to reproductive isolation - the two groups can no longer reproduce or produce fertile offspring ◊ When groups are reproductively isolated, they are different species
  7. 7. Reproductive isolation ◊ Takes a long time • In fastest breeding organisms - 10s - 100s of years • In slower breeding organisms - 1000s to millions of year Gestation 660-760 days, 5 years between births Gestation 12-13 days, births every year
  8. 8. Extinction is Forever :’( ◊ Extinction - an entire species ceases to exist http://aso.gov.au/titles/historical/tasmanian-tiger-footage/clip1/
  9. 9. Who is vulnerable to extinction? ◊ Endemic species - found in only one place ◊ Resource specialist species - eat a limited food range or live in only one type of habitat
  10. 10. Types of extinction ◊ Background extinction - low rate of species extinction that occurs all the time - on average 1-5 species/million/year Does it really matter?
  11. 11. ◊ Mass extinction = significant rise in extinction rate where large groups of species are wiped out ◊ ~ 250 mya about 95% of all species went extinct (dinosaurs)
  12. 12. Extinction and biodiversity ◊ When species go extinct, it opens new habitat and resources for other species - possibly leading to the formation of new species
  13. 13. Quick Think ◊ How would you respond to someone that says that because extinction is a natural process, we should not worry when a species becomes endangered due to human activities?
  14. 14. Big Idea #5 ◊ Biodiversity increases the sustainability to ecosystems
  15. 15. How do we measure species diversity? ◊ 2 major components: • Species richness - the number of different types of species • Species evenness (aka species number) - the relative abundance of each species
  16. 16. Simple example ◊ High School A has 1000 students • 350 white students • 400 black students • 250 Hispanic students ◊ High School B has 1000 students • 950 white students • 20 black students • 30 Hispanic students
  17. 17. More “real” example ◊ Tropical rain forest • 10,000s of different species, but low numbers of each type ◊ Deciduous forest • Only a few dozen different species, but high numbers of each one
  18. 18. Where is it most diverse? ◊ It varies with the geographic location ◊ On average, there are more plants and animals near the equator, and the numbers decline as you move toward the poles (plus ocean bottom) Most diverse
  19. 19. ◊ Four MOST species rich environments: • Tropical rain forests • Coral reefs • Ocean bottom • Large tropical lakes
  20. 20. High species richness ◊ Areas that have high species richness also have higher primary productivity and tend to be more stable ecosystems • More plants support more consumers • More consumers and plants means more connections
  21. 21. Islands ◊ Theory of island biogeography - the number of species on an island is determined by 2 things: immigration rate and extinction rate
  22. 22. 2 Things about the island affect these rates: ◊ 1. Size of the island • Smaller islands have less species because it is a smaller target out there for colonizers ◊So lower immigration rate
  23. 23. ◊ Smaller islands also have higher extinction rates • Have fewer resources and less ecosystem diversity
  24. 24. ◊ 2. Distance from the mainland • Closer to the mainland tends to have higher immigration rate and thus more species
  25. 25. This work is important because ◊ We create islands when we develop land ◊ Scientists use this theory to determine how big the island needs to be to maintain biodiversity
  26. 26. Quick Think ◊ If you could design a healthy, sustainable ecosystem, but you had to choose between high species richness and low evenness, or the opposite, which would you choose and why?
  27. 27. Big Idea #6 ◊ Each species plays an important role in its ecosystem
  28. 28. Ecological Niche ◊ The role that a species plays in the ecosystem • It includes everything that affects its survival and reproduction • Water, sunlight needs • Space requirements • Temperature tolerance • Food, resource needs
  29. 29. Habitat ◊ Where a species lives ◊ (Niche is the WAY it lives)
  30. 30. 2 main types of niches ◊ Generalists - broad niche • Can live in many places • Eats a variety of foods • Can tolerate a range of conditions • Examples: mice, deer, raccoons, humans, flies
  31. 31. ◊ Specialists - narrow niche • Only live in one type of habitat • Use one or just a few food types • Tolerate a small range of environmental conditions • Examples: tiger salamanders, Giant pandas, flamingos, koalas
  32. 32. Pros and Cons of each type ◊ Generalist - • More competition • More adaptable to change ◊ Specialist • Little or no competition • Not adaptable to change
  33. 33. 5 especially important niches ◊ Native species ◊ Nonnative species ◊ Keystone species ◊ Indicator species ◊ Foundation species (aka ecosystem engineers) Muskrat - invasive in CA
  34. 34. Native species ◊ Species that normally live in a given area • They have evolved along with the other native species and have intricate connections with them
  35. 35. Nonnative species ◊ Aka alien, invasive, exotic ◊ Accidentally or deliberately introduced
  36. 36. ◊ Not always bad - most crops and livestock are nonnative species ◊ Sometimes they ARE bad - in 1957 Brazil introduced wild African bees (aka “killer bees”) to increase honey bees. These bees out-competed native bees and led to a decrease in honey production
  37. 37. More on nonnative species ◊ Sometimes - an introduces species just dies out • The new area is not favorable to it
  38. 38. ◊ Sometimes, the nonnative species flourishes, but with no harm to other organisms • Habitat is favorable • Native species peacefully coexist with it
  39. 39. ◊ Sometimes - nonnative species takes over • Often there are no predators for this species, since it hasn’t evolved alongside them • This gives the nonnative a competitive advantage
  40. 40. Indicator Species ◊ Provide ecologists with an early warning system for damage to the ecosystem ◊ They are the canaries in a coal mine
  41. 41. Examples: ◊ Birds - found almost everywhere, heavily affected by environmental damage, especially chemical pesticides
  42. 42. Examples ◊ Amphibians - breathe partially through skin, so very sensitive to changes in water quality
  43. 43. Keystone species ◊ Have a large effect on the number and type of other species in the ecosystem
  44. 44. Examples: ◊ Top predators - feed on and help regulate the size of of other species ◊ Pollinators - control the size of plant populations
  45. 45. Effects of losing a keystone species ◊ When a keystone species is lost - it leads to population crashes and extinctions of other species
  46. 46. Foundation Species ◊ Aka ecosystem engineers ◊ Play a major role in creating the ecosystems in which they live
  47. 47. Examples: ◊ Elephants pull out or break small trees in the African savannah ◊ This allows grass to grow and benefits other grazers and open plains predators
  48. 48. Examples: ◊ Beavers - build dams to create ponds that other species benefit from
  49. 49. Quick Think ◊ Should we devote more of our budget to protecting keystone and foundation species, perhaps at the peril of other species? Explain your reasoning.

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