LIVING IN THE ENVIRONMENT 17 TH MILLER/SPOOLMAN Chapter 5 Biodiversity, Species Interactions, and Population Control
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LIVING IN THE ENVIRONMENT 17TH MILLER/SPOOLMAN
Chapter 5
Biodiversity, Species Interactions, and Population Control
Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction? • Habitat
• Hunted: early 1900s
• Partial recovery
• Why care about sea otters? • Ethics
• Tourism dollars
• Keystone species
Southern Sea Otter
Fig. 5-1a, p. 104
5-1 How Do Species Interact?
• Concept 5-1 Five types of species interactions—competition, predation, parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an ecosystem.
Species Interact in Five Major Ways
• Interspecific Competition
• Predation
• Parasitism
• Mutualism
• Commensalism
Most Species Compete with One Another for Certain Resources
• For limited resources
• Ecological niche for exploiting resources
• Some niches overlap
Some Species Evolve Ways to Share Resources
• Resource partitioning
• Using only parts of resource
• Using at different times
• Using in different ways
Resource Partitioning Among Warblers
Fig. 5-2, p. 106
Fig. 5-2, p. 106
Blackburnian
Warbler
Black-throated
Green Warbler
Cape May
Warbler
Bay-breasted
Warbler
Yellow-rumped
Warbler
Cape May
Warbler
Stepped Art
Blackburnian
Warbler
Black-throated
Green Warbler
Yellow-rumped
Warbler
Bay-breasted
Warbler
Fig. 5-2, p. 106
Specialist Species of Honeycreepers
Fig. 5-3, p. 107
Fig. 5-3, p. 107
Fruit and seed eaters Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Kona Grosbeak
Crested
Honeycreeper Akiapolaau
Maui Parrotbill Apapane
Unknown finch ancestor
Most Consumer Species Feed on Live Organisms of Other Species (1)
• Predators may capture prey by
1. Walking
2. Swimming
3. Flying
4. Pursuit and ambush
5. Camouflage
6. Chemical warfare
Predator-Prey Relationships
Fig. 5-4, p. 107
Most Consumer Species Feed on Live Organisms of Other Species (2)
• Prey may avoid capture by
1. Run, swim, fly
2. Protection: shells, bark, thorns
3. Camouflage
4. Chemical warfare
5. Warning coloration
6. Mimicry
7. Deceptive looks
8. Deceptive behavior
Some Ways Prey Species Avoid Their Predators
Fig. 5-5, p. 109
Fig. 5-5a, p. 109
(a) Span worm
Fig. 5-5b, p. 109
(b) Wandering leaf insect
Fig. 5-5c, p. 109
(c) Bombardier beetle
Fig. 5-5d, p. 109
(d) Foul-tasting monarch butterfly
Fig. 5-5e, p. 109
(e) Poison dart frog
Fig. 5-5f, p. 109
(f) Viceroy butterfly mimics monarch
butterfly
Fig. 5-5g, p. 109
(g) Hind wings of Io moth resemble
eyes of a much larger animal.
Fig. 5-5h, p. 109
(h) When touched, snake
caterpillar changes shape to look
like head of snake.
(d) Foul-tasting monarch butterfly
(e) Poison dart frog
Stepped Art
(h) When touched,
snake caterpillar changes
shape to look like head of snake.
(a) Span worm (b) Wandering leaf insect
(c) Bombardier beetle
(f) Viceroy butterfly mimics
monarch butterfly
(g) Hind wings of Io moth
resemble eyes of a much
larger animal.
Fig. 5-5, p. 109
Science Focus: Threats to Kelp Forests
• Kelp forests: biologically diverse marine habitat
• Major threats to kelp forests
1. Sea urchins
2. Pollution from water run-off
3. Global warming
Purple Sea Urchin
Fig. 5-A, p. 108
Predator and Prey Interactions Can Drive Each Other’s Evolution
• Intense natural selection pressures between predator and prey populations
• Coevolution
• Interact over a long period of time
• Bats and moths: echolocation of bats and sensitive hearing of moths
Coevolution: A Langohrfledermaus Bat Hunting a Moth
Fig. 5-6, p. 110
Some Species Feed off Other Species by Living on or in Them
• Parasitism
• Parasite is usually much smaller than the host
• Parasite rarely kills the host
• Parasite-host interaction may lead to coevolution
Parasitism: Trout with Blood-Sucking Sea Lamprey
Fig. 5-7, p. 110
In Some Interactions, Both Species Benefit
• Mutualism
• Nutrition and protection relationship
• Gut inhabitant mutualism
• Not cooperation: it’s mutual exploitation
Fig. 5-8, p. 110
Mutualism: Hummingbird and Flower
Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish
Fig. 5-9, p. 111
Fig. 5-9a, p. 111 (a) Oxpeckers and black rhinoceros
Fig. 5-9b, p. 111 (b) Clownfish and sea anemone
In Some Interactions, One Species Benefits and the Other Is Not Harmed
• Commensalism
• Epiphytes
• Birds nesting in trees
Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree
Fig. 5-10, p. 111
5-2 What Limits the Growth of Populations?
• Concept 5-2 No population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources.
Most Populations Live Together in Clumps or Patches (1)
• Population: group of interbreeding individuals of the same species
• Population distribution
1. Clumping
2. Uniform dispersion
3. Random dispersion
Most Populations Live Together in Clumps or Patches (2)
• Why clumping?
1. Species tend to cluster where resources are available
2. Groups have a better chance of finding clumped resources
3. Protects some animals from predators
4. Packs allow some to get prey
Population of Snow Geese
Fig. 5-11, p. 112
Generalized Dispersion Patterns
Fig. 5-12, p. 112
Fig. 5-12a, p. 112
(a) Clumped (elephants)
Fig. 5-12b, p. 112
(b) Uniform (creosote bush)
Fig. 5-12c, p. 112
(c) Random (dandelions)
Populations Can Grow, Shrink, or Remain Stable (1)
• Population size governed by
• Births
• Deaths
• Immigration
• Emigration
• Population change =
(births + immigration) – (deaths + emigration)
Populations Can Grow, Shrink, or Remain Stable (2)
• Age structure
• Pre-reproductive age
• Reproductive age
• Post-reproductive age
Some Factors Can Limit Population Size
• Range of tolerance
• Variations in physical and chemical environment
• Limiting factor principle
• Too much or too little of any physical or chemical factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance
• Precipitation
• Nutrients
• Sunlight, etc
Trout Tolerance of Temperature
Fig. 5-13, p. 113
Fig. 5-13, p. 113
Lower limit
of tolerance
Higher limit
of tolerance
No
organisms
Few
organisms Abundance of organisms
Few
organisms
No
organisms
Po
pu
lati
on
siz
e
Zone of
physiological
stress
Optimum range Zone of
physiological
stress
Zone of
intolerance
Low Temperature High
Zone of
intolerance
No Population Can Grow Indefinitely: J-Curves and S-Curves (1)
• Size of populations controlled by limiting factors: • Light
• Water
• Space
• Nutrients
• Exposure to too many competitors, predators or infectious diseases
No Population Can Grow Indefinitely: J-Curves and S-Curves (2)
• Environmental resistance
• All factors that act to limit the growth of a population
• Carrying capacity (K)
• Maximum population a given habitat can sustain
No Population Can Grow Indefinitely: J-Curves and S-Curves (3)
• Exponential growth
• Starts slowly, then accelerates to carrying capacity when meets environmental resistance
• Logistic growth
• Decreased population growth rate as population size reaches carrying capacity
Logistic Growth of Sheep in Tasmania
Fig. 5-15, p. 115
Fig. 5-15, p. 115
2.0 Population
overshoots
carrying
capacity
Carrying capacity
1.5
Population recovers
and stabilizes
Nu
mb
er
of
sh
eep
(m
illi
on
s)
.5
Exponential
growth
Population
runs out of
resources
and crashes
1.0
1800 1825 1850 1875 1900 1925
Year
Science Focus: Why Do California’s Sea Otters Face an Uncertain Future?
• Low biotic potential
• Prey for orcas
• Cat parasites
• Thorny-headed worms
• Toxic algae blooms
• PCBs and other toxins
• Oil spills
Population Size of Southern Sea Otters Off the Coast of So. California (U.S.)
Fig. 5-B, p. 114
Case Study: Exploding White-Tailed Deer Population in the U.S.
• 1900: deer habitat destruction and uncontrolled hunting
• 1920s–1930s: laws to protect the deer
• Current population explosion for deer
• Spread Lyme disease
• Deer-vehicle accidents
• Eating garden plants and shrubs
• Ways to control the deer population
Mature Male White-Tailed Deer
Fig. 5-16, p. 115
When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash
• A population exceeds the area’s carrying capacity
• Reproductive time lag may lead to overshoot
• Population crash
• Damage may reduce area’s carrying capacity
Exponential Growth, Overshoot, and Population Crash of a Reindeer
Fig. 5-17, p. 116
Fig. 5-17, p. 116
2,000 Population
overshoots
carrying
capacity
1,500 Population
crashes
1,000
500 Carrying
capacity
Nu
mb
er
of
rein
deer
1910 1920 1930 1940 1950
0
Year
Species Have Different Reproductive Patterns (1)
• Some species
• Many, usually small, offspring
• Little or no parental care
• Massive deaths of offspring
• Insects, bacteria, algae
Species Have Different Reproductive Patterns (2)
• Other species
• Reproduce later in life
• Small number of offspring with long life spans
• Young offspring grow inside mother
• Long time to maturity
• Protected by parents, and potentially groups
• Humans
• Elephants
Under Some Circumstances Population Density Affects Population Size
• Density-dependent population controls
• Predation
• Parasitism
• Infectious disease
• Competition for resources
Several Different Types of Population Change Occur in Nature
• Stable
• Irruptive • Population surge, followed by crash
• Cyclic fluctuations, boom-and-bust cycles • Top-down population regulation
• Bottom-up population regulation
• Irregular
Population Cycles for the Snowshoe Hare and Canada Lynx
Fig. 5-18, p. 118
Fig. 5-18, p. 118
160
140 Hare
Lynx
100
120
80
60
Po
pu
lati
on
siz
e (
tho
usan
ds)
20
40
1845 1855 1865 1875 1885 1895 1905 1915 1925 1935
0
Year
Humans Are Not Exempt from Nature’s Population Controls
• Ireland
• Potato crop in 1845
• Bubonic plague
• Fourteenth century
• AIDS
• Global epidemic
5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
• Concept 5-3 The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession.
Communities and Ecosystems Change over Time: Ecological Succession
• Natural ecological restoration
• Primary succession
• Secondary succession
Some Ecosystems Start from Scratch: Primary Succession
• No soil in a terrestrial system
• No bottom sediment in an aquatic system
• Takes hundreds to thousands of years
• Need to build up soils/sediments to provide necessary nutrients
Primary Ecological Succession
Fig. 5-19, p. 119
Fig. 5-19, p. 119
Balsam fir, paper birch,
and white spruce forest
community
Jack pine, black spruce, and aspen Heath mat Small herbs
and shrubs Lichens and mosses
Exposed rocks
Balsam fir, paper birch, and white spruce forest community
Jack pine, black spruce, and aspen Heath mat
Small herbs and shrubs Lichens and
mosses Exposed rocks
Stepped Art
Fig. 5-19, p. 119
Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession (1)
• Some soil remains in a terrestrial system
• Some bottom sediment remains in an aquatic system
• Ecosystem has been
• Disturbed
• Removed
• Destroyed
Natural Ecological Restoration of Disturbed Land
Fig. 5-20, p. 120
Fig. 5-20, p. 120
Mature oak and hickory forest
Shrubs and small pine seedlings
Young pine forest with developing understory of oak and hickory trees
Perennial weeds and grasses
Annual weeds
Annual weeds
Mature oak and hickory forest Young pine forest
with developing understory of oak and hickory trees
Shrubs and small pine seedlings Perennial
weeds and grasses
Stepped Art
Fig. 5-20, p. 120
Secondary Ecological Succession in Yellowstone Following the 1998 Fire
Fig. 5-21, p. 120
Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession (2)
• Primary and secondary succession • Tend to increase biodiversity • Increase species richness and interactions among species
• Primary and secondary succession can be interrupted by • Fires • Hurricanes • Clear-cutting of forests • Plowing of grasslands • Invasion by nonnative species
Science Focus: How Do Species Replace One Another in Ecological Succession?
• Facilitation
• Inhibition
• Tolerance
Succession Doesn’t Follow a Predictable Path
• Traditional view
• Balance of nature and a climax community
• Current view
• Ever-changing mosaic of patches of vegetation
• Mature late-successional ecosystems
• State of continual disturbance and change
Living Systems Are Sustained through Constant Change
• Inertia, persistence
• Ability of a living system to survive moderate disturbances
• Resilience
• Ability of a living system to be restored through secondary succession after a moderate disturbance
• Some systems have one property, but not the other: tropical rainforests
Three Big Ideas
1. Certain interactions among species affect their use of resources and their population sizes.
2. There are always limits to population growth in nature.
3. Changes in environmental conditions cause communities and ecosystems to gradually alter their species composition and population sizes (ecological succession).
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