SBS 4e Lecture Ch03 PC
Transcript of SBS 4e Lecture Ch03 PC
-
7/29/2019 SBS 4e Lecture Ch03 PC
1/62
2011 Pearson Education, Inc.
Lecture Outlines
Chapter 3
Environment:The Science behind the
Stories
4th Edition
Withgott/Brennan
-
7/29/2019 SBS 4e Lecture Ch03 PC
2/62
2011 Pearson Education, Inc.
This lecture will help you understand:
Natural selection How evolution influences
biodiversity
Reasons for speciesextinction
Ecological organization
Population characteristics
Population ecology
Conserving biodiversity
-
7/29/2019 SBS 4e Lecture Ch03 PC
3/62
2011 Pearson Education, Inc.
Striking gold in Costa Rica
In 1964, Golden toads were
discovered in Monteverde,Costa Rica
The mountainous cloud
forest has a perfect climatefor amphibians
They became extinct within25 years
- Climate changes dryingeffect on the forest
- A lethal fungus
-
7/29/2019 SBS 4e Lecture Ch03 PC
4/62
2011 Pearson Education, Inc.
Evolution generates biodiversity
Species = a population or group of populations
- Whose members share characteristics
- They can breed with one another and producefertile offspring
Population = a group of individuals of a species thatlive in the same area
Evolution = means change over time
- Biological evolution: genetic change inpopulations over time
- Genetic changes lead to changes in appearance,
functioning or behavior over generations
-
7/29/2019 SBS 4e Lecture Ch03 PC
5/62
2011 Pearson Education, Inc.
Natural selection
Evolution may be random
- Or directed by natural selection
Natural Selection = traits that enhance survival andreproduction
- Are passed on more frequently to future generations- Than those that do not
-
7/29/2019 SBS 4e Lecture Ch03 PC
6/62
2011 Pearson Education, Inc.
Evolution by natural selection
It is one of the best-supported and most illuminating
concepts in all science
It is the standpoint of modern biology
We must understand it to appreciate environmental
science
Knowing ecology and learning the history of life
Evolutionary processes influence pesticide
resistance, agriculture, medicine, health, etc.
In 1858, both Darwin and Wallace proposed natural
selection as the mechanism of evolution
-
7/29/2019 SBS 4e Lecture Ch03 PC
7/62 2011 Pearson Education, Inc.
Natural selection shapes organisms
Premises of natural selection:
- Organisms struggle to survive and reproduce
- Organisms produce more offspring than can
survive
- Individuals of a species vary in theircharacteristics due to genes and the environment
- Some individuals are better suited to theirenvironment and reproduce more effectively
Natural selection acts on genetic variation
-
7/29/2019 SBS 4e Lecture Ch03 PC
8/62 2011 Pearson Education, Inc.
Genetic variation
Adaptation = the process where, over time,
characteristics (traits) that lead to better reproductivesuccess
- Become more prevalent in the population
Adaptive trait (adaptation) = a trait that promotesreproductive success
Mutations = accidental changes in DNA that may bepassed on to the next generation
- Non-lethal mutations provide the genetic variation onwhich natural selection acts
Sexual reproduction also leads to variation
-
7/29/2019 SBS 4e Lecture Ch03 PC
9/62 2011 Pearson Education, Inc.
Natural selection acts on genetic variation
Natural selection changes
characteristics through:
Directional selection =drives a feature in onedirection
Stabilizing selection =favors intermediate traits
- Preserving the status quo
Disruptive selection = traitsdiverge in two or moredirections
-
7/29/2019 SBS 4e Lecture Ch03 PC
10/62 2011 Pearson Education, Inc.
Environmental conditions affect selection
Environmental conditions determine the pressures naturalselection exerts
- These pressures affect who survives and reproduces
- Traits evolve that allow success in that environment But traits that promote success at one time or place may
not do so at another
Natural selection weeds out unfit individuals
- It also elaborates and diversifies traits that mayproduce new species
-
7/29/2019 SBS 4e Lecture Ch03 PC
11/62 2011 Pearson Education, Inc.
Selective pressures influence adaptation
Related species in
different environments- Experience different
pressures
- Evolve different traits
Convergent evolution =
unrelated species mayevolve similar traits
- Because they live insimilar environments
-
7/29/2019 SBS 4e Lecture Ch03 PC
12/62 2011 Pearson Education, Inc.
Evidence of natural selection is everywhere
It is evident in every adaptation of every organism
Artificial Selection = the process of selectionconducted under human direction
- Producing the great variety of dog breeds and foodcrops
-
7/29/2019 SBS 4e Lecture Ch03 PC
13/62 2011 Pearson Education, Inc.
Evolution generates biological diversity
Biological diversity (biodiversity) = the variety of lifeacross all levels of biological organization
- Species
- Genes
- Populations
- Communities
Scientists have described 1.8 million species
- Up to 100 million species may exist
- Tropical rainforests are rich in biodiversity
-
7/29/2019 SBS 4e Lecture Ch03 PC
14/62 2011 Pearson Education, Inc.
Speciation produces new types of organisms
The process of generating new
species from a single species
Allopatric speciation: speciesformation due to physical
separation of populations- The main mode of speciation
- Populations can be separatedby glaciers, rivers, mountains
- Each population gets its ownset of mutations
-
7/29/2019 SBS 4e Lecture Ch03 PC
15/62 2011 Pearson Education, Inc.
Another type of speciation
Sympatric speciation = species form from populationsthat become reproductively isolated within the same area
- Feed in different areas- Mate in different seasons
- Hybridization between two species
- Mutations
-
7/29/2019 SBS 4e Lecture Ch03 PC
16/62
2011 Pearson Education, Inc.
Speciation results in diverse life forms
How do major groups diverge over time?
Phylogenetic trees (cladograms) = showrelationships among species, groups, genes, etc.
- Scientists can trace how certain traits evolved
-
7/29/2019 SBS 4e Lecture Ch03 PC
17/62
2011 Pearson Education, Inc.
The fossil record
Fossil: an imprint in stone of a dead organism
Fossil record: the cumulative body of fossils worldwide
The fossil record shows:
- Life has existed on Earth for at least 3.5 billion years
- Earlier types of organisms evolved into later ones
- The number of species has increased over time
- Most species have gone extinct
- There have been several mass extinctions in the past
-
7/29/2019 SBS 4e Lecture Ch03 PC
18/62
2011 Pearson Education, Inc.
Extinction
Extinction = the disappearanceof a species from Earth
- Species last 1-10 millionyears
Biological diversity is nowbeing lost at an astounding rate
- This loss of species is
irreversible
Number of species = speciation - extinction
-
7/29/2019 SBS 4e Lecture Ch03 PC
19/62
2011 Pearson Education, Inc.
Extinction is a natural process, but
Humans profoundly affect rates of extinction Biodiversity loss affects people directly
- Food, fiber, medicine, ecosystem services
-
7/29/2019 SBS 4e Lecture Ch03 PC
20/62
2011 Pearson Education, Inc.
Some species are more vulnerable to
extinction
Extinction occurs when the environment changes rapidly
- Natural selection can not keep up
Many factors cause extinction:
- Severe weather, climate change, changing sea levels
- New species, small populations
- Specialized species
Endemic species = a species only exists in a certain,specialized area
- Very susceptible to extinction
- These species usually have small populations
-
7/29/2019 SBS 4e Lecture Ch03 PC
21/62
2011 Pearson Education, Inc.
Many U.S. amphibian species are vulnerable
Many U.S. amphibians have very small ranges
- They are vulnerable to extinction- The Yosemite toad, Houston toad, Florida bog frog
40 salamander species are restricted to areas the size of
a typical county
Some U.S. salamander species live on top of single mountains
-
7/29/2019 SBS 4e Lecture Ch03 PC
22/62
2011 Pearson Education, Inc.
Earth has had several mass extinctions
Background extinction rate = extinction usually occurs
one species at a time
Mass extinction events = killed off massive numbers
of species at once- Occurred five times in Earths history
- 50-95% of all species went extinct at one time
Cretaceous-Tertiary (K-T) event: 65 million years ago
- Dinosaurs went extinct End-Permian event: 250 million years ago
- 75-95% of all species went extinct
-
7/29/2019 SBS 4e Lecture Ch03 PC
23/62
2011 Pearson Education, Inc.
The sixth mass extinction is upon us
Humans are causing the sixth mass extinction event- Resource depletion, population growth, development
- Destruction of natural habitats
- Hunting and harvesting of species
- Introduction of non-native species
It is 100-1,000 times higher than the background rate and
rising
Amphibians are disappearing the fastest- 170 species have already vanished
It will take millions of years for life to recover
-
7/29/2019 SBS 4e Lecture Ch03 PC
24/62
2011 Pearson Education, Inc.
The geologic record
-
7/29/2019 SBS 4e Lecture Ch03 PC
25/62
2011 Pearson Education, Inc.
Macroevolution
-
7/29/2019 SBS 4e Lecture Ch03 PC
26/62
2011 Pearson Education, Inc.
Ecology is studied at several levels
Ecology and evolution are
tightly intertwined
Biosphere = the total livingthings on Earth
- And the areas they inhabit
Community = interactingspecies living in the samearea
Ecosystem = communitiesand the nonliving materialand forces they interact with
-
7/29/2019 SBS 4e Lecture Ch03 PC
27/62
2011 Pearson Education, Inc.
Levels of ecological studies
Population ecology = investigates the dynamics ofpopulation change
- The factors affecting the distribution and abundance ofmembers of a population
- Why some populations increase and others decrease
Community ecology = focuses on patterns of speciesdiversity and interactions
Ecosystem ecology = studies living and nonlivingcomponents of systems to reveal patterns
- Nutrient and energy flows
-
7/29/2019 SBS 4e Lecture Ch03 PC
28/62
2011 Pearson Education, Inc.
Each organism has habitat needs
Habitat = the environment where an organism lives- It includes living and nonliving elements
Habitat use = each organism thrives in certainhabitats, but not in others
- Results in nonrandom patterns of use
Habitat selection = the process by which organismsactively select habitats in which to live
- Availability and quality of habitat are crucial to anorganisms well-being
- Human developments conflict with this process
-
7/29/2019 SBS 4e Lecture Ch03 PC
29/62
2011 Pearson Education, Inc.
A specialized frog
Epiphytes grow on trees for support- Obtaining water from the air
- They collect pools of rainwater and pockets of leaflitter
- Frogs lay their eggs inthese rainwater pools
-
7/29/2019 SBS 4e Lecture Ch03 PC
30/62
2011 Pearson Education, Inc.
Habitats vary
Habitats vary with the body size and needs of species
- A soil mite vs. an elephant
Species have different habitat needs at different times
- Migratory birds use different habitats duringmigration, summer and winter
Species use different criteria to select habitat
- Soil, topography, vegetation, other species
- Water temperature, salinity, prey
Species survival depends on having suitable habitat
-
7/29/2019 SBS 4e Lecture Ch03 PC
31/62
2011 Pearson Education, Inc.
Organismal ecology: niche
Niche = an organisms use of resources- Along with its functional role in a community
- Habitat use, food selection, role in energy and
nutrient flow, interactions with other individuals
Specialists = have narrow niches and specific needs
- Extremely good at what they do
- But vulnerable when conditions change
Generalists = species with broad niches
- They use a wide array of habitats and resources
- They can live in many different places
-
7/29/2019 SBS 4e Lecture Ch03 PC
32/62
2011 Pearson Education, Inc.
Population characteristics
All populations showcharacteristics that helpscientists predict theirfuture dynamics
Population size = thenumber of individualorganisms present at agiven time
- Numbers can increase,decrease, cycle orremain the same
-
7/29/2019 SBS 4e Lecture Ch03 PC
33/62
2011 Pearson Education, Inc.
Population characteristics
Population density = the number of individuals in apopulation per unit area
Large organisms usually have low densities
- They need many resources and a large area to survive
High densities make it easier to find mates
- But increase competition and vulnerability to predation
- Increased transmission of diseases
Low densities make it harder to find mates- But individuals enjoy plentiful resources and space
-
7/29/2019 SBS 4e Lecture Ch03 PC
34/62
2011 Pearson Education, Inc.
Population characteristics
Population distribution(dispersion) = spatialarrangement of organisms
Random = haphazardly located
individuals, with no pattern Uniform = individuals are
evenly spaced
- Territoriality, competition
Clumped= arranged accordingto availability of resources
- Most common in nature
-
7/29/2019 SBS 4e Lecture Ch03 PC
35/62
2011 Pearson Education, Inc.
Sex ratio = proportion of males to females
- In monogamous species, a 1:1 sex ratio maximizespopulation growth
Age distribution (structure) = the relative numbers
of organisms of each age in a population- Age structure diagrams (pyramids) = show the age
structure of populations
In species that continue growing as they age
- Older individuals reproduce more (i.e. a tree)
- Experience makes older individuals better breeders
Population characteristics
-
7/29/2019 SBS 4e Lecture Ch03 PC
36/62
2011 Pearson Education, Inc.
Birth and death rates
Type I: more deaths at olderages
Type II: equal number ofdeaths at all ages
Type III: more deaths at
young ages
Survivorship curves = the likelihood of death varies with
age
F f f l i h
-
7/29/2019 SBS 4e Lecture Ch03 PC
37/62
2011 Pearson Education, Inc.
Four factors of population change
Natality = births within the population Mortality = deaths within the population
Immigration = arrival of individuals from outside the
population Emigration = departure of individuals from the
population
Births and immigration add individuals
- Deaths and emigration remove individuals
Crude birth (death) rates: number of births (deaths) per1000 individuals per year
P l i h
-
7/29/2019 SBS 4e Lecture Ch03 PC
38/62
2011 Pearson Education, Inc.
Population growth rate
Natural rate of population growth =
(Crude birth rate)(crude death rate)
- Population change due to internal factors
Population growth rate =
(Crude birth rate + immigration rate)(Crude death rate+ emigration rate)
- Net changes in a populations size/1000/year
Growth rate as a percent =
- Population growth rate * 100%
- Populations of different sizes can be compared
E ti l l ti th
-
7/29/2019 SBS 4e Lecture Ch03 PC
39/62
2011 Pearson Education, Inc.
Exponential population growth
Exponential growth
- A population increases by afixed percent
- Graphed as a J-shaped
curve Exponential growth cannot
be sustained indefinitely
It occurs in nature with a:
- Small population- Low competition
- Ideal conditions
-
7/29/2019 SBS 4e Lecture Ch03 PC
40/62
2011 Pearson Education, Inc.
Limiting factors restrain population growth
Limiting factors = physical, chemical and biologicalattributes of the environment
- They restrain population growth
Environmental resistance = all limiting factors takentogether
- Stabilizes the population size
- Space, food, water, mates, shelter, suitable breedingsites, temperature, disease, predators
- Aquatic systems: salinity, sunlight, temperature, etc.
C i it
-
7/29/2019 SBS 4e Lecture Ch03 PC
41/62
2011 Pearson Education, Inc.
Carrying capacity
Carrying capacity = themaximum population sizeof a species that itsenvironment can sustain
Limiting factors slow andstop exponential growth
- An S-shaped logisticgrowth curve
Many factors contribute to environmental resistance and
influence a populations growth rate and carrying capacity
P l ti d it i t li iti f t
-
7/29/2019 SBS 4e Lecture Ch03 PC
42/62
2011 Pearson Education, Inc.
Population density impacts limiting factors
Density-dependent factors = limiting factors whoseinfluence is affected by population density
- Increased density increases the risk of predation andcompetition for mates
- Results in the logistic growth curve
- Larger populations have stronger environmentalresistance
Density-independent factors = limiting factors whoseinfluence is not affected by population density
- Events such as floods, fires, and landslides
P f t l i ti t ft f d
-
7/29/2019 SBS 4e Lecture Ch03 PC
43/62
2011 Pearson Education, Inc.
Perfect logistic curves arent often found
C i iti h
-
7/29/2019 SBS 4e Lecture Ch03 PC
44/62
2011 Pearson Education, Inc.
Carrying capacities can change
Environments are complex and ever-changing
- Changing carrying capacities
Humans lower environmental resistance for themselves
- Increasing our carrying capacity- Technologies overcome limiting factors
By increasing carrying capacity for humans
- We have reduced the carrying capacity for countlessother organisms
- Calling into question our own long-term survival
-
7/29/2019 SBS 4e Lecture Ch03 PC
45/62
2011 Pearson Education, Inc.
Reproductive strategies vary among species
Biotic potential = an organisms capacity to produceoffspring
K-selected species = species with long gestation periodsand few offspring
- Have a low biotic potential
- Stabilize at or near carrying capacity
- Good competitors
r-selected species = species which reproduce quickly
- Have a high biotic potential
- Little parental care, populations fluctuate greatly
-
7/29/2019 SBS 4e Lecture Ch03 PC
46/62
2011 Pearson Education, Inc.
Population changes affect communities
As the population of one species declines, other speciesmay appear
Human development displaces other species and threatensbiodiversity
As Monteverde dried out, species disappeared
- Golden toads, harlequin frogs and more had beenpushed from their cloud-forest habitat into extinction
- 20 of 50 frog species, 2 lizard species went extinct Species from lower, drier habitats appeared
- 15 species tolerant of drier conditions had moved in
Conserving biodiversity
-
7/29/2019 SBS 4e Lecture Ch03 PC
47/62
2011 Pearson Education, Inc.
Conserving biodiversity
Human development, resource extraction andpopulation pressure are speeding changes
- In populations and communities
Impacts threatening biodiversity have complex social,
economic and political roots
- We must understand these factors to solve problems
Costa Rica and its environment
-
7/29/2019 SBS 4e Lecture Ch03 PC
48/62
2011 Pearson Education, Inc.
Costa Rica and its environment
Past economic and social forces still threaten CostaRicas species and ecological communities
- Lush forests are seen as obstacles to agriculture and for
timber- The countrys population grew to 3.34 million
- Pasture land increased from 12% to 33%
- Forests decreased from 80% to 25%- Species were declining and becoming endangered
Costa Ricas species were in danger
-
7/29/2019 SBS 4e Lecture Ch03 PC
49/62
2011 Pearson Education, Inc.
Costa Ricas species were in danger
Few people saw the need to conserve biological resources
- Until it became clear they were being rapidly lost
Costa Rica is protecting its environment
-
7/29/2019 SBS 4e Lecture Ch03 PC
50/62
2011 Pearson Education, Inc.
Costa Rica is protecting its environment
The privately managed 10,500 ha (26,000 acre)
Monteverde Cloud Forest Reserve was founded in 1972
- To protect the forest, its plants and animals
Costa Rica created the countrys first national parks and
protected areas in 1970- Centered on areas of spectacular scenery
- Protecting valuable tropical dry forests, turtle nesting
beaches, coral reef systems Government support remains strong
- Over 25% of its land is under some type of protection
Costa Ricos protection is paying off
-
7/29/2019 SBS 4e Lecture Ch03 PC
51/62
2011 Pearson Education, Inc.
Costa Rico s protection is paying off
Ecotourism: tourists visit protected areas
- Providing thousands of jobs and billions of dollarsto local economies
But parks are still under-protected and underfunded
- Restoration is a step beyond preservation
Conclusion
-
7/29/2019 SBS 4e Lecture Ch03 PC
52/62
2011 Pearson Education, Inc.
Conclusion
The fundamentals of evolution and population ecologyare integral to environmental science
Natural selection, speciation and extinction helpdetermine earths biodiversity
Understanding how ecological processes function at thepopulation level is crucial to protecting biodiversity
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
53/62
2011 Pearson Education, Inc.
QUESTION: Review
Which of the following is NOT a part of the process ofnatural selection?
a) Once grown, organisms generally dont have tostruggle to survive
b) Organisms produce more young than can survive
c) Individuals vary in their genetic characteristics
d) Some individuals are better suited to their
environment than others
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
54/62
2011 Pearson Education, Inc.
QUESTION: Review
What happens as a result of adaptation?
a) Species have lower reproductive success and lowersurvival.
b) Species have higher reproductive success and higher
survival.c) Species have higher reproductive success and lower
survival.
d) Species have lower reproductive success and highersurvival.
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
55/62
2011 Pearson Education, Inc.
QUESTION: Review
Directional selection would result in which of the
following?
a) Dogs with black coats evolving whiter coats in colderareas
b) Red and white flowers interbreeding, producing pinkflowers
c) Fish evolving bigger eyes as the water gets muddier
d) A population of birds, some with thicker beaks thateat seeds, and others with thinner beaks that eatinsects
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
56/62
2011 Pearson Education, Inc.
QUESTION: Review
Allopatric speciation would occur in:
a) One population that mates in May, and another thatmates in June
b) Two populations separated by the Mississippi River
c) One population that feeds in tree branches, anotherfeeds on tree trunks
d) A population with a mutation that turns fur a differentcolor than usual
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
57/62
2011 Pearson Education, Inc.
QUESTION: Review
Which of these species is MOST vulnerable to extinction?
a) A species with a population size of 500 individuals
b) A species distributed in one county of the United
Statesc) A species that eats many different plant species
d) A species that has hundreds of offspring
QUESTION: Review
-
7/29/2019 SBS 4e Lecture Ch03 PC
58/62
2011 Pearson Education, Inc.
QUESTION: Review
A community is defined as:
a) The total of living things on Earth
b) Members of the same population that can interbreed
c) Interacting species in an area
d) Species and the nonliving material they interact with
QUESTION: Viewpoints
-
7/29/2019 SBS 4e Lecture Ch03 PC
59/62
2011 Pearson Education, Inc.
QUESTION: Viewpoints
Should we care whether a species goes extinct?
a) Yes, because all life is important and valuable.
b) Yes, because we are causing this wave of
extinction, so we should fix it.c) We should not, because its natural.
d) I dont care; it really does not affect me.
QUESTION: Viewpoints
-
7/29/2019 SBS 4e Lecture Ch03 PC
60/62
2011 Pearson Education, Inc.
QUESTION: Viewpoints
Do you think humans are subject to limiting factors and,ultimately, a fixed carrying capacity?
a) Yes, although we have raised the carrying capacity,there are limits to the number of humans Earth cansupport.
b) Yes, but technology will keep raising the carryingcapacity, so its not much of a problem.
c) No, humans are no longer constrained byenvironmental limits, due to our technology andability to manipulate the environment.
d) I dont care; it really does not affect me.
QUESTION: Interpreting Graphs and Data
-
7/29/2019 SBS 4e Lecture Ch03 PC
61/62
2011 Pearson Education, Inc.
QUESTION: Interpreting Graphs and Data
Which type of distribution is a
result of competition betweenindividuals?
a) Random
b) Uniform
c) Clumped
d) None of these
QUESTION: Interpreting Graphs and Data
-
7/29/2019 SBS 4e Lecture Ch03 PC
62/62
QUESTION: Interpreting Graphs and Data
What does this graph
show?a) The effects of
carrying capacity onpopulation growth
b) A population thatkeeps growing
c) The effects ofexponential growth
d) The effects ofincreasing carryingcapacity