41 Ch 42 Ch 44 Ecology Ecology study of interactions between organisms and their environments science of relationships studied by ecologists Abiotic Factors nonliving parts of an organisms environment ID: 781164
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Slide1
UNIT 7: Ecology
Ch
40:
Ch
41:
Ch
42:
Ch
44:
Slide2Ecology
Ecology
: study of interactions between organisms and their environments – science of relationships, studied by ecologists
Abiotic Factors: non-living parts of an organism’s environmentAir currents, temperature, moisture, light, soil Biotic Factors: all the living things that inhabit the environmentsalmon, bears, trees, algae, microscopic organisms
Slide3Population Ecology
Population
: group of organisms that interbreed with one another more often than they interbreed with other members of their
speciesPopulation ecology investigates the factors that influence the size, distribution, and other properties of natural populationsDemography [Demographics]: the study of human population size, density, distribution, movement, and birth and death rates
Slide4Population Ecology
Population size
: total number of individuals in population
Population density: number of individuals per unit area or volumePopulation distribution describes how individuals are distributed – often determined by the availability of resources
Slide5Population Distribution
Clumped
: closer than would be expected by chance
Most common, resource are clumpedHippopotamusesNear-Uniform: more evenly spaced than would be expected by chancebreeding colonies, competition for resourcesNesting seabirds
Slide6Population Distribution
Random
: distributed randomly when environmental resources are uniformly distributed
Rare, resources are uniformly distributed, proximity to others is neither beneficial or detrimentaldandelions
Slide7Population Size
In nature, populations continually change their size
Immigration
: Movement of individuals into a population, Population increasesEmigration: Movement of individuals out of a population, Population decreasesZero population growth: Interval in which births equal deathsSome populations may not be able to grow because resources won’t allow it
Slide8Population Limits
Density-Independent
: factor that
DOES NOT depend on the number of members in the populationcrowding does not influence the likelihood of their occurrence or the magnitude of their effectUsually abioticnatural
events like the weather (drought, flooding, etc.) or human interference
Slide9Population Limits
Density-Dependent
: factor that
DOES depends on the number of members in a populationCause birth rates to slow and death rates to riseUsually bioticCompetition – density is high, resources are low
Disease – density is highParasites
– density is high
Slide10Population Growth
Exponential Growth
: Population size increases by the same proportion with every time interval
Number of new individuals increases every generationBirth rate exceeds death rateJ-shaped curve
Slide11Population Growth
Logistic Growth
: population slows or stops after a period of rapid growth
Population grows exponentially, as crowding rises, density-dependent factors begin to limit growthS-shaped curveCarrying Capacity: maximum number of species an environment can support for the long term
Limited by energy, water, oxygen, available nutrients
Slide12Population Growth
Carrying capacity is species-specific, environment-specific, and can change over
time
When populations overshoot carrying capacity they will decrease until they are below it, then stabilize!
Slide13Population Growth
Boom and Bust
:
Population increases and decreases rapidlyCan be caused by weather conditionsPredator + prey interactions
Slide14Reproductive Patterns
Species differ
in the ways
they distribute parental investment among offspring.Species of organisms vary in the number of births per reproductive cycle, the age that reproduction begins, and in the life span of the organismsPlants and animals are placed into groups based on their reproductive factors
Slide15Reproductive Patterns
r
-Selection
: produce as many offspring as possible in a short period of timeOpportunistic species, give little parental careLive in
a fluctuating environmentRarely reach carrying capacity, competition lowUsually
small organisms (mice, fruit
fly) with short
life
spans
Usually
controlled by density-independent factors
Slide16Reproductive Patterns
K
-Selection
: produce fewer offspring that have a better chance of survivingequilibrial species that produce high quality offspring, give a lot of parental careLive in predictable environment
Rarely reach carrying capacity, competition lowLarge organisms (elephants)
with
long
life spans
Usually controlled by
density-dependent
factors
Slide17Human Population Growth
For most of history the human populate grew very slowly and environmental conditions kept us below carrying capacity
We have made advancements that allow us to change carrying capacity
Agricultural advancesTechnology & medicineMigration into new climate zones
Slide18Human Population
Scientists
are concerned about the population reaching or exceeding the carrying
capacityResources from the biosphere used by each person must be limited
Slide19Future Growth
Age Structure Pyramids
:
diagrams show the age distribution of individuals in a populationThe broader the base of an age structure diagram, the greater proportion of young people, and the greater expected growth1.9 billion people are about to enter reproductive age – we aren’t slowing down anytime soon!
Slide20Slide21Demographic Transition
The demographic transition model describes how changes in population growth often unfold in four stages of economic
development
Demographic Transition: change in population from high birth/death rates to low birth/death ratesHighly developed countries use far more resources than those in less developed countries and generate more waste and pollutionUnited States uses more than three times average
Slide22CH 41 Community Ecology
Community
:
all the populations of all species that live in a particular place at the same timeCommunities differ in their species diversitySymbiosis: A relationship in which two species have a prolonged close association“Living together”Two species that interact closely for generations can coevolveCan be a commensal, mutualistic, or parasitic relationship
Slide23Symbiosis
Mutualism
: symbiotic relationship in which
two species benefit by taking advantage of one anotherAcacia tree provides food for ants, ants protect tree from those that would eat the leavesIn some mutualisms, neither species can complete its life cycle without the otherYucca plants and the moths that pollinate them
Slide24Symbiosis
For some mutualists, the main benefit is defense
Sea anemone and anemone fish
Slide25Symbiosis
Commensalism
: symbiotic relationship in which one organism benefits – the other is not affected
Spanish moss on a treeBarnacles on a whale
Slide26Symbiosis
Parasitism
: symbiotic relationship in which one
species (parasite) feeds on another (host), without immediately killing it [one benefits, the other is harmed]
Some live within the hostTapeworms, HeartwormsSome feed on external surface of the hostTicks, FleasSome insects lays eggs in other insects, and their young devour the host from the inside
Slide27Symbiosis
Many parasites are pathogens that cause disease in hosts
Parasites are adapted with traits that allow
them to locate hosts and feed undetectedTicks move toward heat and carbon dioxideParasitic louse – born male, when then find a host [fish], they eat its tongue and “replace” it, becoming female
Slide28https://
www.youtube.com/watch?v=XuKjBIBBAL8
https://
www.youtube.com/watch?v=vMG-LWyNcAs
Slide29Competition
Limited resources often create competition among species in a community – this adversely affects both species
Niche
:Can include tolerable temperature range, species it eats, and places it can breedA flowering plant’s niche would include its soil, water, light, and pollinator requirementsThe more similar the niches of two species are, the more intensely they will compete
Slide30Competition
Competition can include one species actively preventing the other from accessing resources or both species purposely using a resource in order to reduce its availability
When a resource is a limiting factor, some species will drive the other to extinction
Conversely, some species adapt to sharing a limited resource in order to limit competition
Slide31Predation
Predation
:
One species (predator) captures, kills, and eats another species (prey)The abundance of prey affects how many predators a community can supportPredators & prey exert pressures on each otherPrey adapt their defenses, predators improve their capture skills
Slide32Predation
Defensive adaptations include
Hard parts that are difficult to eat, chemicals that taste bad, tricking predators
Vomiting FulmarExploding AntsWhite-tailed Deer Fake Death
Slide33Predation
Mimicry
:
One species evolving to resemble another speciesCamouflage: Adaptations that allow organisms to blend in with their surroundingsUsed by both predator and preyVaries by species, but environment is often the most important factor
Slide34Change in Communities
Succession
: The changes that take place in a community as it gets older
Succession happens SLOWLY! It can be hard to see happening.Succession is Primary or Secondary
Slide35Primary Succession
Primary Succession
:
Occurs at an area of newly exposed rock (no soil) that has never been occupied by any living thingPioneer Species: first species to colonize a new habitatMosses, lichens, and some flowering annualsBreak down rock to create soil
Slide36Primary Succession
Slide37Secondary Succession
Secondary Succession
:
The orderly and predictable change that takes place after a community of organisms has been removed, but the soil has remained intact.Occurs when a community has been removed due to fire, flood, windstorm, etc.New species may begin to occupy the habitatOver time, the species belonging to the mature community may return
Slide38Secondary Succession
Slide39Succession
Climax Community
:
stable, mature community that results when there is little change in the composition of speciesfinal stage of succession, but unlikely to occur because of ecological disturbancesSpecies composition of a community changes frequently and unpredictablyRandom events can determine the order in which species arrive and affect the course of succession
Slide40Succession
Indicator species
are the first to do poorly when conditions change,
provide an early warningtrout are highly sensitive to pollutants and cannot tolerate low oxygen levelsKeystone species are species that have a disproportionately large effect on community structureThe loss or addition of a keystone could destabilize a community
Slide41Endemic Species
evolved in a particular community and exists nowhere else
Exotic Species
evolved in one community and later became established in a different oneInvasive Species are exotic species that harm members of its new community