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-Linnaeus: Developed the idea that organisms are related (classifier, shapes & sizes).
-Malthus: There are more people than resources (Economy Theory).
-Curvier: Fossils change in time.
-Lyell: Geological features constantly change in time.
-Lamarck proposed that organisms accumulate information during a generation and than pass the information gathered onto their offspring.
-Darwin and Wallace's theory was based on adaptive traits being passed to the next generation based on environment.
1.Individuals in population vary in heritable traits
2.Organisms produce more offspring than can survive
1.Individuals well-suited to environments tend to leave more offspring
2.Favorable traits accumulate in populations.
1. Artificial Selection: By controlling survival you can make different species
2. The Fossil Record: Provides evidence of species that are linked
3. Homology: Similarity of common ancestry
4. Direct Observation of Evolutionary Change: Evolution of pesticide resistance.
5. Biogeography: The geographic distribution of species causing endemic species.
-Natural selection is a mechanism for change
-Natural selection explains the existence of adaption
-Selection can only act on existing variation
-Evolution is limited by historical constraints
-Adaptations are often compromises
-Chance, natural selection and the environment interact.
Why is genetic variation important?
-Variation is the raw material for evolution
-Environmental (and selective pressure) is unlikely to remain the same
*** No variation = No opportunities for adaptive evolution via natural selection.
1.Mutation Change in the gene structure of a chromosome; only way to form new alleles
2.Genetic Drift Change due to random chance of events
3.Gene Flow Genes flow between populations
4.Natural Selection Traits less favorable die due to survival success
-Mutation is chromosome specific
-Natural selection is population development through advantage
-Gene flow is variation crossing community barriers
-Genetic drift is due to chance events
*** Usually they occur together, the question is which is the key.
-Natural selection is the only consistently positive mechanism for change because it works on existing traits, weeding out the bad ones.
-The other mechanisms are due to chance and could be good or bad.
1. Directional Selection: Favors individuals at one end of the phenotypic range.
2. Disruptive Selection: Favors individuals at opposite ends of the phenotypic range.
3. Stabilizing Selection: Favors individuals in the middle of the phenotypic range.
-Intersexual Selection: Acts on traits that affect success in being chosen by a mate
-Intrasexual Selection: Acts on traits that affect success in competition with members of the same sex.
-Small populations experience greater effects of drift.
-Loss of genetic diversity
-Population stays small ---> Drift continues ---> Positive feed-back loop
-Genetic drift is important to conservation because in small populations drift can become more important/effective than selection.
-Drift can become more powerful than selection.
-Becomes hard to pass good alleles because of drift.
What is sexual selection? What are two types of sexual selection?
-Sexual selection is natural selection related to mating success.
1. Intersexual: Affects success in being chosen by a mate.
2. Intrasexual: Affects success in competition over a mate.
1. Pre-zygotic Barriers: Barriers to reproduction before the production of a zygote.
2. Post-zygotic Barriers: Barriers to reproduction after the production of a zygote
Mechanical Isolation: Mating may be attempted, but prevented by different physical structures.
Gametic Isolation: Sperm of one species may not be able to fertilize eggs from another.
Hybrid Viability: The zygote forms, but it does not survive very well.
Hybrid Fertility: The zygote forms and survives well, but it cannot reproduce.
Hybrid Breakdown: The zygote forms and can reproduce for one generation, but their offspring cannot reproduce.
-Allopatric Speciation: Occurs when there is geographic separation of populations over time and there is enough divergence to become reproductively isolated.
-Sympatric Speciation: Speciation that occurs without geographic isolation
-Examples of Allopatric Speciation:
1. Antelope squirrels on opposite ends of the grand canyon
2. Endemic species formed on islands
-Examples of Sympatric Speciation
1. Polyploidy: change in # of chromosomes in gametes
2. Disruptive selection
-Punctuated Equilibrium: Periods of little change interrupted by short periods of rapid change.
-Gradualism: Big differences accumulate between species via slow and steady change.
-The evolution of new species from a common ancestor upon introduction of or to new environmental opportunities
*Example: Dinosaurs die, mammals take over
-The study of the distribution and abundance of organisms
-Distribution: Where the organisms live?
-Abundance: How many are there in certain areas?
-Can a species get there?
-Once it is there can it survive and reproduce?
-Humans are the worst components of global homogenism in the world.
-We move everything everywhere.
Abiotic Factors: Non-living components of an environment (oxygen, water, pH, temperature, sunlight, soil characteristics.
Biotic Factors: Living components of an environment (predation, parasitism, competition, disease).
What are some physical abiotic factors? Some chemical abiotic factors?
-Examples of Physical Abiotic Factors:
(Soil characteristics, water, sunlight)
-Examples of Chemical Abiotic Factors:
(pH, nitrogen allowance, oxygen levels)
-Plants and animals do not go to certain areas based on predators, parasites, competition for resources, and/or disease.
-This limits distribution because organisms are likely to travel to areas that are best for their survival needs.
-Climate variation creates distinct biomes
-Within these biomes there are specific species that are like certain areas based on their abiotic factors.
Biome: Area characterized by specific ecological communities and/or specific climate regimes.
Organismal Ecology Studies organisms physiology and behavior
Population Ecology Studies factors on species populations
Community Ecology Studies interactions between species.
Ecosystem Ecology Studies energy flow
Global Ecology Studies the biosphere.
-Density: Number of individuals per unit of volume
-Dispersion: Pattern of spacing among individuals in a population
*** Density is related to the amount of individuals, dispersion is related to the areas they live.
1. Clumped Dispersion: Individuals aggregate in patches
2. Uniform Dispersion: Individuals spread evenly
-Territorial behavior, competition
3. Random Dispersion: Independent spacing for each individual.
-Occurs when no interactions.
Type I Survivorship: Low death rates during early and middle life, increase later in life
Type II Survivorship: Constant death rate over a lifespan
Type III Survivorship: High death rates for the young, than slower for survivors.
Generation Time: The average amount of time between the birth of an individual and the birth of it's offspring
Intrinsic Growth Rate: Birth Rate - Death Rate
They are related because Intrinsic Growth Rate is based off the generation time of a species
dN/dt = rmaxn
*** Not that (r) ignores immigration and emigration
r = intrinsic growth rate
n = number of individuals in a population
t = time
-Logistic growth factors in a variable known as (K) or the carrying capacity
-Carrying Capacity: Point of population stabilization
-Intrinsic Growth Rate affects population growth by deciding whether the population is increasing or decreasing
-If the population is increasing then the Carrying Capacity will limit the population confirming that no population can increase indefinitely
-The indirect effect of top predators on lower trophic levels.
***The idea that links in a food chain determine who is limited by what.
-Top-down Limitation: When a top predator controls the structural dynamics of a primary producer.
-Bottom-up Limitation: Refers to control by nutrient supply and productivity; primary producers control the ecosystem structure by limiting predators.
-Dominant Species: Those that are most abundant or have the highest biomass.
-Keystone Species: Exerts strong control on a community by their roles or niches
-Ecosystem Engineers: Influence other species by physically altering the environment.
1. Richness: the number of species in a given area.
2. Evenness: The distribution of individuals among different species.
*** Richness involves the number of species while evenness involves the specific areas of high numbers.
1. Habitat Loss or Degradation: Destruction of areas of species populations
2. Introduced Species: Invasive species take over natural ranges
3. Over-Exploitation: Harvesting at higher rates than population can increase.
-Biodiversity is important because loss of diversity threatens human well-being.
-Diversity leads to stability and lack of diversity leads to extinction.
-Wide environmental tolerance
-Large native range
-High rate of population increase
-No, effects are difficult to predict because events are up to chance
-Regardless of the effect, we do know there will be a change ecosystem function.
-Overexploitation: Harvesting of plant animal populations at higher rates than the population can increase
-Indicators usually are the dramatic drop in an industry due to lack of a popular ecological product (Fishing industry).
-Education and awareness
-Restoration and remediation (Restoration Ecology: The attempt to restore a system to what it used to resemble).
Herbivory: Animals eat plants.
Carnivory: Animals eat animals.
-Be difficult to see
-Defend yourself with chemicals
-Mimic a defended species
-Be hard to eat with spines or spikes
-Vigilance: be loud!
-Hose them down (skunk)
-There are so many defenses against predation due to the Life-Dinner Principle.
-Life-Dinner Principle: Because selection acts more strongly on prey, then prey should be more evolutionary advanced than predators.
-Mutualism: Host and symbiont both benefit. The relationship is often obligatory, meaning one cannot survive without the other.
-Comensalism: Symbiont benefits, but host is unaffected. The relationship is usually not obligatory
-In order for interspecific competition to occur two organisms must share the same niche.
-Niche: The sum total of an organism resources in it's environment. How an organisms "fits" into it's environment.
-Character Displacement: Tendency for characteristics of co-occurring species to diverge more than populations of the same species that are alone.
-Important for speciation because greater differences = more likely to become reproductively isolated.
-Trophic level: The position an organism holds on a food chain.
*** Primary producer --> secondary consumer --> tertiary consumer --> quaternary consumer --> top predatory
-Primary producers maker their own chemical energy while secondary consumers must eat primary producers in order to obtain their chemical energy.
-Energy is necessary for survival.
-It is possible to feed more people with plants due to the 10% rule
-The 10% Rule: Only ten percent of the energy absorbed from each level of consumer travels to the next level of consumer. The rest of the energy is expelled through heat.
-Introduced invasive species to ecosystems
-Increased levels of atmospheric CO2
-Over-exploited plants and animals to the point of extinction
-Degraded ecosystem services
-Air quality regulation
1, In 50 years humans have radically altered ecosystems
2. Changes that brought gains have threatened future development
3. Degradation of ecosystems could get worse
4. Workable solutions require change in policy (not usually welcome).
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