LIVING IN THE ENVIRONMENT 17 TH 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

Specialist Species of Honeycreepers Fig. 5-3, p. 107

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 7.Luring

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

(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

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

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5. bobtail squid and bioluminscent bacteria

6. Nile Crocodile (Crocodylus niloticus) with Egyptian Plover or

1.5-2 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.

2.Most Populations Live Together in Clumps or Patches (1) Population: group of interbreeding individuals of the same species Population distribution 1.Clumping Uniform dispersion 3.Random dispersion

3. 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

Generalized Dispersion Patterns Fig. 5-12, p. 112

4. Populations Can Grow, Shrink, or Remain Stable (1), Population size governed by Births Deaths Immigration Emigration Population change = (births + immigration) – (deaths + emigration) crisis/412396/

5. Populations Can Grow, Shrink, or Remain Stable (2) Age structure Pre-reproductive age Reproductive age Post-reproductive age Mostly made up of reproductive stage? Mostly made up of past reproductive stage? Mostly made up of evenly distributed groups? How does child survival rate affects population growth?

6. Some Factors Can Limit Population Size Range of tolerance Range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop and function

Generally speaking, warm freshwater fish populations need dissolved oxygen concentrations of not less that 4.0 milligrams/liter (mg/l), while cold water fish species require not less than 5.0 mg/l dissolved oxygen.

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 Important limiting factors in aquatic zones: Temperature Sunlight Nutrient availability Oxygen salinity

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 Environmental resistance determines Carrying Capacity. It makes it sound kind of as if it was the environment vs populations. :P Carrying capacity (K) Maximum population a given habitat can sustain

8. 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

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

10. Exponential Growth, Overshoot, and Population Crash of a Reindeer Fig. 5-17, p. 116 For some, the transition between exponential and logistic is not so smooth Reproduction time lag

Species Have Different Reproductive Patterns (1) Some species (r pattern) Many, usually small, offspring Little or no parental care Massive deaths of offspring Insects, bacteria, algae

Species Have Different Reproductive Patterns (2) Other species (K pattern) 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 Most organisms are somewhere in between.

12. Under Some Circumstances Population Density Affects Population Size Density-dependent population controls Predation Parasitism Infectious disease Competition for resources Density –independent populaltion controls

13. Several Different Types of Population Change Occur in Nature Stable: fluctuate slightly above and bellow carrying capacity. Irruptive Population surge, followed by crash. Linked to seasonal changes in weather or nutrition Cyclic fluctuations, boom-and-bust cycles Top-down population regulation (through predation) Bottom-up population regulation (depend on resources) that is, bottom-up controls arise from near the bottom of the food web, below the trophic level in question. food web Irregular

Population Cycles for the Snowshoe Hare and Canada Lynx Fig. 5-18, p. 118

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

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

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 Time

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

Annual weeds Mature oak and hickory forest Young pine forest with developing understory of oak and hickory trees Time 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

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

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 are not in state of equilibrium 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

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).