Transcript Inquiry into Life, Eleventh Edition

Inquiry into Life
Eleventh Edition
Sylvia S. Mader
Chapter 33
Lecture Outline
Prepared by: Wendy Vermillion
Columbus State Community College
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Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
33.1 Scope of ecology
• Ecological terms
– Ecology- study of interactions of organisms with other organisms
and with the physical environment
– Modern ecology encompasses levels of study
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Organism- the level of individual
Population-all members of same species inhabiting an area
Community- all populations in an area
Ecosystem-a community and its physical environment
Biosphere-all communities on Earth
– Ecological succession- a change in community composition over
time
– Climax community- associated with a particular geographical
area
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Levels of organization in a coral reef
• Fig. 33.1
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Scope of ecology cont’d.
• Ecological succession
– Occurs after a disturbance
• Primary succession occurs in areas where there is no soil
• Secondary succession occurs when there is soil available
– Pioneer species- the first to come in and colonize in secondary
succession
– Succession proceeds through stages as illustrated on the
following slide
• The slide illustrates terrestrial succession
• Succession also occurs in aquatic communities
– Bodies of fresh water proceed through stages and are
eventually filled in by sediments
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Secondary succession in a forest
• Fig. 33.2
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Scope of ecology cont’d.
• Models of succession
– Climax-pattern model-particular areas will always lead to a
specific climax community
• Based on the fact that climate determines what plants survive
• Exact composition of climax community need be the same
– For example, the climax community in an area may be
deciduous forest, but the tree species may differ
– Facilitation model-each successive community prepares the
environment for the next
• Grasses are necessary before shrubs, and then shrubs before trees
– Inhibition model-colonizing species hold on to space until they
die or are damaged
– Tolerance model-different species can colonize at the same time
• Random chance determines which arrives first
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33.2 Patterns of population growth
• Patterns of population growth
– Biotic potential- highest rate of per capita increase
• Depends upon:
– Usual number of offspring per reproduction
– Chances of offspring surviving until reproduction
– How often each individual reproduces
– Age at which reproduction begins
– Exponential growth
• Graphing number of organisms against time gives a J-shaped curve
– Lag phase-slow growth period because population is small
– Exponential growth phase-accelerates and population exhibits
biotic potential
– Continues until environmental resistance occurs
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Patterns of population growth cont’d.
• Patterns of growth cont’d.
– Logistic growth
• Produces an S-shaped curve
• Population growth levels off when environmental resistance is met
– Lag phase-slow growth, population is small
– Exponential growth phase-accelerated growth, biotic potential
– Deceleration phase-population growth slows down
– Stable equilibrium phase-little growth takes place because birth
rate and death rate are about equal
» Occurs at carrying capacity of environment
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Patterns of population growth
• Fig. 33.4
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Patterns of population growth cont’d.
• Survivorship
– Growth curves assume all individuals are identical
• In real life, individuals are in different life stages
– Cohort-group of individuals born at the same time
• Plotting the number surviving over time gives us a survivorship
curve
– Type I survivorship curve- most individuals survive until old age
• Ex: humans
– Type II- survivorship curve- decreases consistently over time
• Ex: songbirds
– Type III survivorship curve- most individuals die early
• Ex: oysters
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Survivorship curves
• Fig. 33.5
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Patterns of population growth cont’d.
• Human population growth
– Doubling time- length of time it takes for population to double its
numbers
– Currently is 53 years
– Has rapidly increased
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1st billion didn’t occur until 1800
2nd billion in 1930
3rd billion in 1960
Current population is over 6 billion
– Must double food, water, energy, jobs just to maintain current
standard of living
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World population growth
• Fig. 33.6
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Patterns of population growth cont’d.
• More-developed versus less-developed countries
– MDC’s
• Population growth is low and standard of living high
• Increased rapidly between 1850 and 1950 due to decreased death
rate
• This was followed by a decrease in birth rate-demographic transition
• Has stabilized at 0.1%
• Germany, Hungary, Italy, Greece, Sweden-actually decreasing in
size
– U.S.- no leveling off
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Patterns of population growth cont’d.
• MDC’s versus LDC’s cont’d.
– LDC’s
• Population growth is expanding rapidly and standard of living is low
• Population of LDC’s could reach 11 billion by 2100
– Most of this increase in Latin America, Africa, and Asia
• Ways to decrease this expected growth are
– Establish/strengthen family planning programs
– Use social progress to reduce desire for large families
– Delay onset of childbearing
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World population growth
• Fig. 33.6
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Patterns of population growth cont’d.
• Age distributions
– Divide populations into 3 groups- dependency, reproductive, and
post reproductive
• Many MDC’s have a stable age structure
– If every couple has 2 children, this results in replacement
reproduction
» Replacement reproduction can eventually lead to zero
population growth
• LDC’s have a younger population so they can be expected to
continue to grow
– The faster replacement reproduction is achieved, the sooner
zero population growth will result
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Age-structure diagrams (1998)
• Fig. 33.7
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33.3 Regulation of population growth
• Types if life history patterns
– Opportunistic pattern
• Small size, mature early, short life span
• Offspring are small, many produced with little paternal care
– Greater numbers increase likelihood some will survive a
population crash
• colonizers
– Equilibrium pattern
• Size of population remains around carrying capacity
• Resources are scarce; those who compete successfully will have
the most offspring
• Large size, slow to mature, long life span
• Specialists instead of colonizers
• Become extinct if normal way of life is destroyed
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Regulation of population growth cont’d.
• Life history patterns cont’d.
– Density-independent factors-abiotic factors such as weather,
natural disasters
• Populations with opportunistic life-history pattern tend to be
controlled by density-independent factors
– Density-dependent factors-biotic factors such as predation,
parasitism, competition
• Populations with equilibrium life-history pattern tend to be controlled
by density-dependent factors
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Life history patterns
• Fig. 33.8
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Regulation of population growth cont’d.
• Competition
– Occurs when members of 2 different species try to utilize the
same resource
– Competitive exclusion principle-no 2 species can occupy the
same ecological niche at the same time
• Ecological niche-role organism plays in the community; includes
habitat, resources used, and interactions
– Resource partitioning
• Slight differences in the way a resource is utilized
• Decreases competition
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Competition between two laboratory
populations of Paramecium
• Fig. 33.9
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Competition between two species of
barnacles
• Fig. 33.10
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Regulation of population growth cont’d.
• Predation
– Predator-prey population dynamics
• Cycling of predator and prey populations
• Occurs when either predators overkill prey, or when prey overuse
resources and their numbers crash
– In either case, predator numbers also decrease from a
decrease in food source
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Predator-prey interaction between a
lynx and a snowshoe hare
• Fig. 33.11
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Regulation of population growth cont’d.
• Antipredator defenses
– Coevolution-two species respond to selective pressure imposed
by the other
• Predator species evolve strategies to get maximum amount of food
with the least expenditure of energy
• Prey species evolve strategies to escape predation
– Mimicry-one species resembles another that has an antipredator
defense
• Can help predator catch food or a prey species avoid capture
• Batesian mimicry-a species that lacks a defense mechanism mimics
another that has if
– Ex: nonstinging insects with black and yellow color like wasp
• Mullerian mimicry-several species with the same defense
mechanism share a common characteristic
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Antipredator defenses
• Fig. 33.12
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Mimicry
• Fig. 33.13
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Regulation of population growth cont’d.
• Symbiosis-interactions between members of 2
populations
– Parasitism- parasite derives nourishment from host
• Parasite benefits and the host is harmed
– Commensalism-one species benefits and the other is neither
harmed nor benefited
– Mutualism- both species benefit
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Egret symbiosis
• Fig. 33.14
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Cleaning symbiosis
• Fig. 33.15
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