Ecology Unit Population Ecology Ecology study of the

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Ecology Unit: Population Ecology • Ecology: study of the interactions between organisms and the

Ecology Unit: Population Ecology • Ecology: study of the interactions between organisms and the living and nonliving components of their environment. Vocabulary • Ecosystem Components: • Abiotic Factors: nonliving. The physical and chemical components of the environment. • Biotic Factors: living, these include all of the living things that affect the organism. © 2011 Pearson Education, Inc.

Review Levels of Organization • Biosphere: most inclusive level of organization. This is the

Review Levels of Organization • Biosphere: most inclusive level of organization. This is the thin volume of earth and its atmosphere that supports live. • Ecosystem: All organisms and the non-living environment. • Community: All the interacting organisms living in an area. • Population: All the members of a species that live in one place at one time. © 2011 Pearson Education, Inc.

Ecology Unit Energy Flow Review • Energy flow through a system involves, producers, consumers

Ecology Unit Energy Flow Review • Energy flow through a system involves, producers, consumers and decomposers • Ecologist use ecological pyramids to represent relationships among trophic levels (ex. Pyramids of Energy, Biomass and Numbers) © 2011 Pearson Education, Inc.

An Energy Pyramid for a Prairie Ecosystem: The 10% Law © 2011 Pearson Education,

An Energy Pyramid for a Prairie Ecosystem: The 10% Law © 2011 Pearson Education, Inc.

Energy Transfer and Loss Heat Secondary Consumer Producer Primary Consumer Heat Chemicals Heat Detritus

Energy Transfer and Loss Heat Secondary Consumer Producer Primary Consumer Heat Chemicals Heat Detritus Feeders © 2011 Pearson Education, Inc.

Ecology Unit • Cycles of matter • Biogeochemical Cycles: nutrients move through the biosphere

Ecology Unit • Cycles of matter • Biogeochemical Cycles: nutrients move through the biosphere in a series of physical and biological processes (unlike energy, nutrients can be used over and over) • Examples: • Water Cycle: alternation of evaporation and transporation, condensation and precipitation • Nitrogen Cycle: decomposers put nitrogen back into soil • Carbon and Oxygen Cycle: involves photosynthesis and respiration. © 2011 Pearson Education, Inc.

Water vapor in atmosphere Evaporation from land & Evaporation transpiration from ocean from plants

Water vapor in atmosphere Evaporation from land & Evaporation transpiration from ocean from plants Precipitation over land Precipitation over ocean The Hydrologic Cycle Reservoirs Processes/ Locations Water in ocean Surface (reservoir) runoff Groundwater seepage © 2011 Pearson Education, Inc.

The Nitrogen Cycle Nitrogen in in Atmosphere Reservoir Producers Uptake Dentitrifying bacteria by plants

The Nitrogen Cycle Nitrogen in in Atmosphere Reservoir Producers Uptake Dentitrifying bacteria by plants Electrical storms produce nitrate Reservoirs Processes/ Locations Trophic Levels/ Organisms Consumers Wastes, Dead bodies Soil bacteria and detritus feeders Ammonia & nitrate Nitrogen-fixing bacteria in legume roots and soil © 2011 Pearson Education, Inc.

The Carbon Cycle CO 22 in atmosphere (reservoir) Reservoirs Burning of CO 2 dissolved

The Carbon Cycle CO 22 in atmosphere (reservoir) Reservoirs Burning of CO 2 dissolved fossil fuels Fire in ocean Respitation (reservoir) Consumers Processes/ Locations Trophic Levels/ Organisms Producers Wastes, Dead bodies Soil bacteria & detritus feeders © 2011 Pearson Education, Inc.

Population Growth • Populations grow with births and immigration • They decline with deaths

Population Growth • Populations grow with births and immigration • They decline with deaths and emigration Population Growth: = Change in population number (Births + Immigration) – (Deaths + Emigration) Species do not occupy all parts of their habitat at once. • Niche: the specific role or way of life of a species within it’s environment. • Niche includes the range of conditions that the species can tolerate, the resources used and the methods used to obtain resources. © 2011 Pearson Education, Inc.

 • Biotic Potential: rate species reproduce if unlimited. • Maximum growth rate given

• Biotic Potential: rate species reproduce if unlimited. • Maximum growth rate given ideal conditions • Produces Exponential Growth • Modifying Factors • Birth Rate • Death Rate • Migration • Immigration – into an area • Emigration – out of an area © 2011 Pearson Education, Inc.

Exponential growth • Each species can increase its population • With favorable conditions •

Exponential growth • Each species can increase its population • With favorable conditions • Exponential growth produces the J-curve: the curve of exponential growth © 2011 Pearson Education, Inc.

Exponential growth of a population • Under unlimited conditions, organisms will have rapid population

Exponential growth of a population • Under unlimited conditions, organisms will have rapid population growth • Carrying capacity (K): the maximum population of a species that a given habitat can support without being degraded • This is the upper limit of population growth © 2011 Pearson Education, Inc.

14 • Environmental Resistance Limits Population Growth • It decreases birth rate and increases

14 • Environmental Resistance Limits Population Growth • It decreases birth rate and increases death rate • Density – Dependent Factors • Predation • Parasitism • Competition • Density – Independent Factors • Weather, pesticides, pollutants, ect. © 2011 Pearson Education, Inc.

Density dependence and independence • Density-dependent factor: increases with increased population density • Predation,

Density dependence and independence • Density-dependent factor: increases with increased population density • Predation, disease, food shortage • Logistic growth occurs when populations become more crowded (approach carrying capacity) • Density-independent factor: one whose effects are independent of the density of the population • Spring freeze, fire • Is not involved in maintaining population equilibrium in the logistic growth © 2011 Pearson Education, Inc.

Environmental resistance • Abiotic and biotic factors cause mortality (death) • Prevents unlimited population

Environmental resistance • Abiotic and biotic factors cause mortality (death) • Prevents unlimited population growth • Environmental resistance: the biotic and abiotic factors that may limit a population’s increase • Biotic: predators, parasites, competitors, lack of food • Abiotic: unusual temperatures, moisture, light, salinity, p. H, lack of nutrients, fire • Environmental resistance can also lower reproduction • Loss of suitable habitat, pollution • Changed migratory habits of animals © 2011 Pearson Education, Inc.

 • Environmental Resistance : • Causes populations to stabilize at or below Carrying

• Environmental Resistance : • Causes populations to stabilize at or below Carrying Capacity • Maximum population size an area can support • Limitations on population growth is necessary Note: Due to environmental resistance, growth levels off and we get a population growth pattern called Logistic Growth (s-shape curve) © 2011 Pearson Education, Inc.

Outcomes of population increase • Logistic growth: some process slows growth so it levels

Outcomes of population increase • Logistic growth: some process slows growth so it levels off near carrying capacity • Results in an S-shaped curve • It levels off at K • As the population approaches K, growth slows • The population remains steady and growth = 0 • The maximum rate of population growth occurs halfway to K © 2011 Pearson Education, Inc.

Populations show logistic growth • J-shaped explosions are often followed by crashes • J-shaped

Populations show logistic growth • J-shaped explosions are often followed by crashes • J-shaped growth results from unusual disturbances • Introduction of a foreign species, a suddenly changed habitat, the elimination of a predator, arrival in a new habitat • Other populations show an S-curve • Followed by cycles of lower and higher numbers around K • Or shoot above K, eventually cycling around K © 2011 Pearson Education, Inc.

Three models of population growth © 2011 Pearson Education, Inc.

Three models of population growth © 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

22 40 Chapter The S-Curve of Population Growth (environmental resistance) Number of Individuals Carrying

22 40 Chapter The S-Curve of Population Growth (environmental resistance) Number of Individuals Carrying Capacity (biotic potential) Equilibrium Exponential Growth Time © 2011 Pearson Education, Inc.

 • Species and Community Interactions: • Ecological niche: organisms habitat • No two

• Species and Community Interactions: • Ecological niche: organisms habitat • No two species ever occupy exactly the same niche • Niches of different species will overlap • What effects the balance of a community of species • Competition • Predation • Symbiosis © 2011 Pearson Education, Inc.

 • Competition • Intraspecific competition: competition between the same species helps control population

• Competition • Intraspecific competition: competition between the same species helps control population size • Interspecific competition: competition between different species. • Competitive exclusion: no two species occupy the same niche • Resource partitioning—similar species live and feed in different areas © 2011 Pearson Education, Inc.

Resource Partitioning © 2011 Pearson Education, Inc.

Resource Partitioning © 2011 Pearson Education, Inc.

Community Interactions • Predation: one organisms kills and eats another • Symbiosis—a close Interaction

Community Interactions • Predation: one organisms kills and eats another • Symbiosis—a close Interaction between Different Species Types of symbiosis: • Parasitism—one organism (parasite) lives on or inside another (host), harmful relationship (ex. Tapeworm) • Commensalism—one benefits, other is neither harmed nor benefits (ex. barnacles attached to whales) • Mutualism—relationship benefits both species (ex. Flowers and insects) © 2011 Pearson Education, Inc.

Predators Help Control Prey Populations 27 40 Chapter © 2011 Pearson Education, Inc.

Predators Help Control Prey Populations 27 40 Chapter © 2011 Pearson Education, Inc.

Population Cycles in Predators and Prey 28 40 Chapter © 2011 Pearson Education, Inc.

Population Cycles in Predators and Prey 28 40 Chapter © 2011 Pearson Education, Inc.

Reproductive strategies: r-strategists • The interplay of environmental resistance and biotic potential drives the

Reproductive strategies: r-strategists • The interplay of environmental resistance and biotic potential drives the success of two reproductive strategies • r-strategists (r-selected species): produce lots of young, but leave their survival to nature • • • Results in low recruitment Rapid reproduction, rapid movement, short life span Adapted to a rapidly changing environment “Boom-and-bust” populations “Weedy” or “opportunistic” species For example, housefly © 2011 Pearson Education, Inc.

Reproductive strategies: K-strategists • K-strategists (K-selected species): lower biotic potential • Care for and

Reproductive strategies: K-strategists • K-strategists (K-selected species): lower biotic potential • Care for and protect young • Live in a stable environment already populated by the species • Larger, longer lived, well-adapted to normal environmental fluctuations • Their populations fluctuate around carrying capacity • Also called equilibrial species • For example, elephant, California condor © 2011 Pearson Education, Inc.

Life histories • Life history: progression of changes in an organism’s life • Age

Life histories • Life history: progression of changes in an organism’s life • Age at first reproduction, length of life, etc. • Visualized in a survivorship graph • Type I survivorship: low mortality in early life • Most live the bulk of their life span (e. g. , humans) • Type III survivorship: many offspring that die young • Few live to the end of their life (oysters, dandelions) • Type II survivorship: intermediate survivorship pattern (squirrels, coral) • K-strategists have a Type I pattern; r-strategists show Type III © 2011 Pearson Education, Inc.

Survivorship curves © 2011 Pearson Education, Inc.

Survivorship curves © 2011 Pearson Education, Inc.

Succession: • Succession: Predictable changes in a community over time, usually as a result

Succession: • Succession: Predictable changes in a community over time, usually as a result of a natural disturbance or human caused disturbance • Existing community is gradually replaced by another community over time Example: volcanic island arises from the sea with no living community – Bare rock © 2011 Pearson Education, Inc.

Succession: Predictable Sequence of Community Changes • Primary succession—bare rock, barren environments • No

Succession: Predictable Sequence of Community Changes • Primary succession—bare rock, barren environments • No previously established ecosystems (ex. Volcanic island arises from sea) • Occurs over a longer period of time (thousands of years) • Pioneer species: lichens – break down rock to soil->Mossgrasses-> shrubs-> trees • Climax community – stable collection of organisms • Secondary succession—occurs in a disturbed, established ecosystem • Plowed field, timbered forest, after mining, fires, etc. • Occurs over shorter time (hundreds of years) © 2011 Pearson Education, Inc.

Succession in Progress Mount St. Helens explosion, 1980 Same view, 20 y later ©

Succession in Progress Mount St. Helens explosion, 1980 Same view, 20 y later © 2011 Pearson Education, Inc.

Primary Succession 36 40 Chapter © 2011 Pearson Education, Inc.

Primary Succession 36 40 Chapter © 2011 Pearson Education, Inc.

Secondary Succession 37 40 Chapter © 2011 Pearson Education, Inc.

Secondary Succession 37 40 Chapter © 2011 Pearson Education, Inc.

Succession in a Freshwater Pond (c) (a) (b) © 2011 Pearson Education, Inc.

Succession in a Freshwater Pond (c) (a) (b) © 2011 Pearson Education, Inc.