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ESSENTIALS OF ECOLOGY 6THMILLER/SPOOLMAN
Chapter 5Biodiversity, Species Interactions, and Population Control
Endangered species: Southern Sea Otter
Fig. 5-1a, p. 104
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 timesg
• Using in different ways
Resource Partitioning Among Warblers
Fig. 5-2, p. 106
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Specialist Species of Honeycreepers
Fig. 5-3, p. 107
Predator‐Prey Relationships
Fig. 5-4, p. 107
Most Consumer Species Feed on Live Organisms of Other Species (2)
• Prey may avoid capture by1. Run, swim, fly2. Protection: shells, bark, thorns3 Camouflage3. Camouflage4. Chemical warfare5. Warning coloration6. Mimicry7. Deceptive looks8. Deceptive behavior
Fig. 5-5a, p. 109
(a) Span worm
Fig. 5-5b, p. 109
(b) Wandering leaf insectFig. 5-5c, p. 109
(c) Bombardier beetle
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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.
Science Focus: Threats to Kelp Forests• Kelp forests: biologically diverse marine habitat
• Major threats to kelp forests1 Sea urchins1. Sea urchins2. Pollution from water run‐off3. Global warming
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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
• CoevolutionCoevolution• 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
Parasitism: Trout with Blood‐Sucking Sea Lamprey
Fig. 5-7, p. 110
Mutualism: Hummingbird and Flower
Fig. 5-8, p. 110
Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish
Fig. 5-9, p. 111
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Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree
Fig. 5-10, p. 111
Most Populations Live Together in Clumps or Patches (1)
• Population distribution 1. Clumping2. Uniform dispersion3. Random dispersionp
Population of Snow Geese
Fig. 5-11, p. 112
Generalized Dispersion Patterns
Fig. 5-12, p. 112
Populations Can Grow, Shrink, or Remain Stable (1)
• Population size governed by• Births• Deaths• Immigrationg• Emigration
• Population change =(births + immigration) – (deaths + emigration)
Populations Can Grow, Shrink, or Remain Stable (2)
• Age structure• Pre‐reproductive age• Reproductive age• Post‐reproductive agep g
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Trout Tolerance of Temperature
Fig. 5-13, p. 113
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)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
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
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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 crashPopulation crash
• Damage may reduce area’s carrying capacity
Exponential Growth, Overshoot, and Population Crash of a Reindeer
Fig. 5-17, p. 116
Species Have Different Reproductive Patterns (2)
• Other species• Reproduce later in life• Small number of offspring with long life spans• Young offspring grow inside motherg p g g• Long time to maturity• Protected by parents, and potentially groups• Humans• Elephants
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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
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
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Natural Ecological Restoration of Disturbed Land
Fig. 5-20, p. 120
Secondary Ecological Succession in Yellowstone Following the 1998 Fire
Fig. 5-21, p. 120
