© Cengage Learning 2015 LIVING IN THE ENVIRONMENT, 18e G. TYLER MILLER SCOTT E. SPOOLMAN © Cengage Learning Biodiversity, Species Interactions, and Population Control

© Cengage Learning 2015 Live in giant kelp forests By the early 1900s they had been hunted almost to extinction Partial recovery since 1977 Why care about sea otters? –Ethics –Tourism dollars –Keystone species Core Case Study: Southern Sea Otters - A Species in Recovery

© Cengage Learning 2015 Southern Sea Otter Fig. 5-1, p. 102

© Cengage Learning 2015 Five types of species interactions— competition, predation, parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an ecosystem 5-1 How Do Species Interact?

© Cengage Learning 2015 Five basic types of species interactions –Interspecific Competition –Predation –Parasitism –Mutualism –Commensalism Most Species Compete with One Another for Certain Resources

© Cengage Learning 2015 Interspecific competition –Most common interaction –Members of two or more species compete to use the same limited resources –Niches overlap –Involves one species becoming more efficient than the other

© Cengage Learning 2015 Resource partitioning –Populations of some species develop adaptations that allow them to reduce or avoid competition with other species for resources. –Competing species evolve specialized traits so that they may use only parts of resource At different times In different ways Some Species Evolve Ways to Share Resources

© Cengage Learning 2015 Cape May Warbler Stepped Art Blackburnian Warbler Black-throated Green Warbler Yellow-rumped Warbler Bay-breasted Warbler Fig. 5-2, p. 103 Sharing the Wealth

© Cengage Learning 2015 Fig. 5-3, p. 104 Fruit and seed eatersInsect and nectar eaters Greater Koa-finch Kuai Akialaoa Amakihi Kona Grosbeak Crested Honeycreeper Akiapolaau Maui Parrotbill Apapane Unkown finch ancestor Specialist Species of Honeycreepers

© Cengage Learning 2015 Predation –A member of one species (predator) feed directly on all or part of a living organism (prey) as part of a food web. –Predator methods: Herbivores-walk, swim, or fly to plants they feed on Carnivores-pursuit and ambush Camouflage Chemical warfare Consumer Species Feed on Other Species

© Cengage Learning 2015 Prey can avoid predation –Swim, run, fly fast –Highly developed senses –Protective shells, thick bark, or spines –Camouflage –Chemical warfare –Warning coloration –Mimicry –Behavioral strategies Consumer Species Feed on Other Species (cont’d.)

Predator-Prey Relationships Fig. 5-4, p. 104

© Cengage Learning 2015 Predator-Prey Relationships Fig. 5-6, p. 106

© Cengage Learning 2015 Intense natural selection pressures between predator and prey populations Coevolution –Interact over a long period of time –Changes in the gene pool of one species can cause changes in the gene pool of the other –Bats and moths Echolocation of bats and sensitive hearing of moths Interactions between Predator and Prey Species

Coevolution Fig. 5-7, p. 107

© Cengage Learning 2015 Parasitism –One species (the parasite) feeds on another organism (the host) by living on or inside the host –Parasite is usually much smaller than the host –Parasite rarely kills the host –Parasite-host interaction may lead to coevolution Some Species Feed off Other Species by Living on or inside Them

Parasitism Fig. 5-8, p. 107

© Cengage Learning 2015 Mutualism –Two species benefit –Nutrition and protective relationship –Gut inhabitant mutualism –Not cooperation – mutual exploitation In Some Interactions, Both Species Benefit

Mutualism Fig. 5-9, p. 108

© Cengage Learning 2015 Commensalism –Benefits one species and has little affect on the other –Epiphytes –Birds nesting in trees In Some Interactions, One Species Benefits and the Other Is Not Harmed

Commensalism Fig. 5-10, p. 108

© Cengage Learning 2015 How do communities and ecosystems respond to changing environmental conditions? –The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession 5-2 Responding to Changing Environmental Conditions

© Cengage Learning 2015 Ecological succession –Gradual change in species composition –Primary succession Gradual establishment of a community in a lifeless areas (no soil in terrestrial ecosystem and no bottom sediment in an aquatic ecosystem) –Secondary succession Areas of environmental disturbance, but some soil or bottom sediment remains Communities and Ecosystems Change over Time: Ecological Succession

© Cengage Learning 2015 Both types of succession are examples of natural ecological restoration –Increase the biodiversity of communities and ecosystems by increasing species richness and interactions among species. –Factors that affect how and rate of succession: 1. facilitation 2. inhibition 3. tolerance

Primary Ecological Succession 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 Fig. 5-11, p. 109

Natural Ecological Restoration 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 Time Fig. 5-12, p. 110

© Cengage Learning 2015 Traditional view –Succession proceeds in an orderly sequence along an expected path until a climax community is reached; balance of nature Current view –Ever-changing mosaic of patches of vegetation in different stages of succession –In a state of continual disturbance and change. Ecological Succession Does Not Follow a Predictable Path

© Cengage Learning 2015 Two aspects of stability or sustainability in living systems: 1. Inertia, or persistence –Ability of a living system to survive moderate disturbances 2. Resilience –Ability of a living system to be restored through secondary succession after a moderate disturbance Living Systems Are Sustained through Constant Change

© Cengage Learning 2015 No population can grow indefinitely because of limitations on resources and because of competition among species for those resources What Limits the Growth of Populations

© Cengage Learning 2015 Population –Group of interbreeding individuals of the same species Population distribution –Clumped –Uniform –Random Most Populations Live in Clumps

© Cengage Learning 2015 –Clumping Most live in clumps. Why? 1. Species cluster for resources 2. Protection from predators 3. Ability to hunt in packs

A School of Anthias Fish Fig. 5-13, p. 111

© Cengage Learning 2015 Population size governed by: –Births and deaths; immigration and emigration Population change = (births + immigration) – (deaths + emigration) Populations Can Grow, Shrink, or Remain Stable

© Cengage Learning 2015 Age structure- –age group distributions can have a strong effect on how rapidly populations grow or decline –Pre-reproductive age –Reproductive age –Post-reproductive age

© Cengage Learning 2015 Range of tolerance –Tolerance to variations in physical and chemical environment –Individuals may have different tolerance ranges because of their genetic makeup, health, and age. Some Factors Can Limit Population Size

© Cengage Learning 2015 Limiting factors: –Factors that determine number of organisms in a population. –Regulate population growth 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 Some Factors Can Limit Population Size

© Cengage Learning 2015 Populations density –Can be a limiting factor –Number of individuals in a given area

© Cengage Learning 2015 Fig. 5-13, p. 113 Lower limit of tolerance Higher limit of tolerance No organisms Few organisms Abundance of organisms Few organisms No organisms Population size Zone of physiological stress Optimum range Zone of physiological stress Zone of intolerance LowTemperatureHigh Zone of intolerance Trout Tolerance of Temperature

© Cengage Learning 2015 To ensure long-term survival of species: Some species: –Have many small offspring –Little parental involvement –Algae, bacteria, and most insects Other species: –Reproduce later in life –Have small number of offspring –mammals Different Species Have Different Reproductive Patterns

© Cengage Learning 2015 There are always limits to population growth in nature –Environmental resistance: combination of all factors that limit population growth Determines the: –Carrying capacity: Maximum population of a given species that a particular habitat can sustain indefinitely No Population Can Grow Indefinitely: J-Curves and S-Curves

© Cengage Learning 2015 Exponential growth –At a fixed percentage per year –J-shaped growth curve –Unlimited resources Logistic growth –Exponential growth that faces environmental resistance –Population size stabilizes at carrying capacity –S-shaped growth curve No Population Can Grow Indefinitely: J-Curves and S-Curves (cont’d.)

Fig. 5-16, p Population overshoots carrying capacity Carrying capacity 1.5 Population recovers and stabilizes Number of sheep (millions).5 Exponential growth Population runs out of resources and crashes Year Environmental resistance Growth of a Sheep Population

© Cengage Learning – deer habitat destruction and uncontrolled hunting 1920s–1930s – laws to protect the deer Current deer population explosion –Spread Lyme disease –Deer-vehicle accidents –Eating garden plants and shrubs How can we control the deer population? Case Study: Exploding White-Tailed Deer Population in the U.S.

White-Tailed Deer Populations Fig. 5-17, p. 115

© Cengage Learning 2015 If a population uses up resources and exceeds the area’s carrying capacity, the reproductive time lag may lead to overshoot: –Subsequent population crash or dieback –Damage may reduce area’s carrying capacity When a Population Exceeds Its Carrying Capacity It Can Crash

© Cengage Learning 2015 Fig. 5-18, p ,000 Population overshoots carrying capacity 1,500 Population crashes 1, Carrying capacity Number of reindeer Year Population Crash

© Cengage Learning 2015 Ireland –Potato crop in 1845 Bubonic plague –Fourteenth century AIDS –Current global epidemic Humans Are Not Exempt from Nature’s Population Controls

© Cengage Learning 2015 Certain interactions among species –Affect their use of resources and their population sizes Changes in environmental conditions –Cause communities and ecosystems to gradually alter their species composition and population sizes (ecological succession) There are always limits to population growth in nature Three Big Ideas

© Cengage Learning 2015 Before European settlers in the U.S., the sea otter ecosystem was complex Settlers began hunting otters –Disturbed the balance of the ecosystem Populations depend on solar energy and nutrient cycling –When these are disrupted biodiversity is threatened Tying It All Together – Southern Sea Otters and Sustainability