unit 13 chapter 50: an introduction to ecology & the biosphere chapter 51: behavioral biology...
TRANSCRIPT
UNIT 13Chapter 50: An Introduction to Ecology & the Biosphere
Chapter 51: Behavioral Biology
Chapter 52: Population Ecology
Chapter 53: Community Ecology
Chapter 54: Ecosystems
Chapter 55: Conservation Biology
Ecology is the scientific study of the interactions between organisms and their environment
Introduction
Ecologists make predictions of what should be observed in the environment
Environment of any organism includes the following components:– Abiotic factors: non-living chemical and physical
factors (temperature, light, water, and nutrients)– Biotic factors: the living components
Organismal: behavioral and physiologicalways individualsinteract with theenvironment
Levels of Ecology
Population: a population is a group of individuals of the same species living in a particular geographic area– Population ecology examines factors that affect
population size and composition
Community:a community consistsof all the organisms ofall the species thatinhabit a particulararea– Community ecology
examines the interactionsbetween populations predation, competition,
and disease
Ecosystem: an ecosystem consists of all the abiotic factors in addition to the entire community of species that exist in a certain area– Ecosystem ecology:
energy flow cycling of chemicals
Climate is the prevailing weather conditions in an area– Temperature, water, light, and wind are major
components of climate
Climate determines the makeup of biomes– Major types of ecosystems
Ex. Desert, tundra, tropical rain forest, grassland, etc.
Temperature & Water
Annual means for temperature and rainfall are reasonably well correlated with the biomes we find in different regions
The tropics between 23.5° north latitude and 23.5° south latitude experience the least seasonal variation and have the highest biodiversity
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Introduction
Ethology is the study of how animals behave in their natural environment
Behavior results from both genes and environment Innate behaviors are fixed, the result of genetics
Learning
Learning is based on experience and results in modification of behavior Maturation: changes resulting from growth
and development Habituation: desensitization to unimportant
stimulus
Imprinting is a short period of learning early in life Usually involves
young recognizing (and becoming attached to) parents
Konrad Lorenz experimented with geese
Classical conditioning is a type of associative learning Animals learn to associate one stimulus
with another Ivan Pavlov experimented with dogs
Ring bell and spray powdered meat in their mouths caused salivation
Eventually, the bell alone caused salivation
Operant conditioning involves trial and error Association with a punishment or reward
Cognition
Cognition is the ability to perceive, store, process and use information from sensory receptors Kinesis: change in activity based on
random behavior Taxis: movement/orientation based on a
stimulus Migration: long-distance movements that
occur regularly
Organism Interactions
Social behavior is any interaction between animals (usually the same species) Agonistic: conflict, usually no harm done Dominance hierarchies: involve ranking of
individuals Alpha organism dominates group
Courtship consists of behaviors that lead to copulation Monogamous – strong bond between male
and female Polygamous – multiple mates exist
Polyandry – female with multiple males Polygyny – male with multiple females
Promiscuous – no lasting bond between males and females
Inclusive Fitness
Most social behaviors are selfish, but some involve helping others Altruism decreases
individual fitness, but increases fitness of group
Related individuals will often help each other survive and/or reproduce Kin selection: individuals help relatives
raise young
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IntroductionIntroduction
A A populationpopulation is a group of the same is a group of the same species that inhabit the same general species that inhabit the same general areaarea
DensityDensity and and distributiondistribution are influenced are influenced by organisms’ interactions with the by organisms’ interactions with the environmentenvironment
Survivorship CurvesSurvivorship Curves
DemographyDemography is the study of the factors is the study of the factors that control the growth and decline of that control the growth and decline of populationspopulations– Survivorship curvesSurvivorship curves reflect births and deaths reflect births and deaths
in a populationin a population Curve types: Type I, Type II, Type IIICurve types: Type I, Type II, Type III
Population GrowthPopulation Growth
The The exponential modelexponential model reflects unlimited reflects unlimited resources for growthresources for growth
The The logistic modellogistic model incorporates limiting incorporates limiting factors into population growthfactors into population growth– NN is the number of individuals is the number of individuals– Carrying capacityCarrying capacity ( (KK) is the maximum ) is the maximum
number of individuals that can be supported number of individuals that can be supported naturallynaturally
Two basic types of species exist based on Two basic types of species exist based on reproductive traitsreproductive traits– K selectionK selection
organisms live/reproduce around Korganisms live/reproduce around K– Long maturation, long lifespan, low deathrate, few Long maturation, long lifespan, low deathrate, few
offspring, several reproductions in lifeoffspring, several reproductions in life
– r selectionr selection populations fluctuate well below Kpopulations fluctuate well below K
– Short maturation, short lifespan, high deathrate, Short maturation, short lifespan, high deathrate, many offspring, one reproductionmany offspring, one reproduction
Limiting factors Limiting factors fall into two categoriesfall into two categories– Density dependentDensity dependent
factors increase their pressure as population factors increase their pressure as population growsgrows
type of negative feedbacktype of negative feedback
– Density independentDensity independent factors unrelated to population size, no feedbackfactors unrelated to population size, no feedback
Negative feedback prevents unlimited Negative feedback prevents unlimited population growthpopulation growth
Some populations go through regular Some populations go through regular “boom and bust” cycles“boom and bust” cycles– Common with predator/prey interactionsCommon with predator/prey interactions
Age structureAge structure is the relative number of is the relative number of individuals at each ageindividuals at each age
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Introduction
• A community is a collection of species living closely enough for potential interaction
• Interspecific interactions involve relationships between species
• An organism’s niche is its biotic and abiotic requirements from its environment• Its role in the environment• Organisms with identical niches cannot coexist
(competitive exclusion principle)
Interspecific Interactions
• Competition, mutualism, commensalism and predation (parasitism) are examples of interspecific interactions
• Predator/prey interactions have “forced” evolution to develop ways to protect prey species from their predators• Coloring, camouflage, toxins, mechanical
defenses, etc.• Herbivory is a type of predation
• Coloration and camouflage are frequently used by nature to aid prey avoid being eaten• Cryptic coloration – traditional camouflage,
deceptive markings• Aposematic coloration – warning colors to
indicate the presence of a toxin• Batesian mimicry – a harmless species
resembles a harmful one• Müllerian mimicry – two (or more) “dangerous”
species have evolved to resemble one another
Trophic Structure
• Food chains and food webs are used to trace the path of energy-containing carbon compounds
Disturbance & Succession
• Disturbances affect community structure and stability• Stability is the ability of a community to persist
• Events like fire, weather, natural disasters and human activity can disturb a community• Some events are routine, while others occur
randomly• Usually considered to have a negative impact,
but actually necessary for development and survival
• Humans are the most widespread source of disturbance and it usually results in a decrease in species diversity
• Succession is the sequence of changes that occur after a disturbance• Primary succession – occur in a lifeless area
• Soil needs to be created first by mosses and lichens
• Secondary succession – occur when an area is cleared by an event
• Soil still exists, grasses and small shrubs grow
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Trophic Relationships
• Trophic relationships involve the cycling of carbon in an ecosystem• Primary producers
are photosynthetic• All consumers
depend on photosynthetic output
• Amount of light energy converted to chemical energy in a given time period is called primary production• Ecosystems vary in their productivity
Primary Production
• Amount of chemical energy converted into a consumer’s biomass is secondary production
Secondary Production
• Joules (J) are unit of energy
• Trophic efficiency is typically ~10%• Amount of energy passed to next trophic
level
• Trophic efficiency has important implications for humans
• Human activity disrupts biogeochemical cycles• Nutrients removed from one part of
biosphere and placed in another
Human Impact
• Agriculture and eutrophication
• Acid precipitation threatens plants and aquatic organisms• Caused by burning fossil fuels
• Toxins introduced into a food web become more concentrated in successive trophic levels• Biological
magnification
• Human activities were depleting atmospheric ozone (O3)• Ozone protects
Earth from UV radiation
• Use of CFC’s is likely cause
• Climate change occurs due to rising CO2 levels in the atmosphere• Greenhouse
effect causes global warming
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