Chapters 3,4, and 5

Introduced Species

• species brought unnaturally into an environment by humans and can destabilize ecosystems

• ex rats brought by ship, cats brought to catch rates, and then cats destroyed habitat and killed eggs and young of native birds

Avian Malaria

• killed native birds at lower elevations

• global warming has allowed it to thrive at higher elevations and decimate more of the bird population

Natural Selection

• traits that enhance survival and reproduction will dominate

• Darwin + Wallace discover natural selection as the mechanism of evolution

• Adaptations are characteristics that lead to beeter reporductive success over generations

  • often caused by mutations which are accidental changes in DNA

• Sexual Reproduction leads to variation

Directional Selection

• drives a feature in one direction

Convergent vs. Divergent Evolution

• Convergent: unrelated species may acquire similar traits due to pressures of natural selection in similar environments

• Divergent: closely related species diverge in appearance due to pressures of natural selection, resulting in a variety of features froma. single ancestor

Levels of organization

Speciation

• process by which new species are generated

• Allopatric: species in different population are physically separated and have different mutations with no gene flow, overtime they are so different that they are unable to breed

Phylogenetic Trees

• diagrams that show relationships in divergence

Taxonomic Classification

Extinction

• the disappearance of a species from earth permanently

• # of species in existence = speciation - extinction

• factors that cause extinction:

  • sever climate/topographic changes

  • invasive species

• Most Vulnerable

  • bottleneck: small population

  • Endemic species: only occur in one region

Mass Extinction

• a lot of species die out compared to the background extinction rate which is a constant rate of extinction as part of evolution

• Cretaceous-Tertiary (KT) event: asteroid impact that killed dinosaurs

• End-Permian Extinction

• Humans are causing the 6th mass extinction due to resource depletion, growing development, and introduction of non-native species

Niches

• organisms thrive in specific habitats and roles that match their trates (habitat selection)

• fill a specific niche in their community

  • narrow niche = specialist

  • broad niche = generalist

• Fundamental Niche: full niche of species

• Realized Niche: portion of niche that is actually fulfilled

Characteristics that help predict population dynamics

• Population Size

• Population Density

• Population Distribution

  • Random

  • Uniform

  • Clumped

• Sex Ratio

• Age Structure/Distribution

• Birth and Death Rates

Survivorship Curves

• Type I: higher death at older age (humans)

• Type II: equal rates of death at all ages (birds)

• Type III: highest death rate at young ages (toads)

Factors in growth

• growth is exponential until a constraint is meant: typically only when conditions are ideal or a species is introduced to a new environment with abundant resources

  • carrying capacity (k value)

    • logistic growth curve

    • overshoot: when pop goes over carrying capacity

Biotic Potential

• K-selected: low biotic potential, longer gestational period, higher survival rates, stabilize close to carrying capacity, larger animals

• R-Selected: high biotic potential, short gestational period, population size fluctuates/often is below carrying capacity, low parental care, smaller

Competition

• when organisms seek the same shared resource

• intraspecific: between members of the same species

• interspecific: between members of different species

Competitive Exclusion Principle

• two species w/ exactly the same requirements cannot coexist in exactly the same habitat

• either one species excludes the other or they find species coexistence where neither fully excludes the other

• species change their behavior to minimize competition

  • causes resource partisioning and character displacement

Exploitive Interactions

• Predation

  • drives cyclical population dynamics

• Parasitism

  • insects that parasitize other insects = parasitoids

  • parasites that caust disease = pathogen

• Herbivory

Mutualism

• 2+ species benefit from interacting

• physically close association = symbiosis (i.e.e algae and fungi => Lichen)

• Pollination

Producers/Autotrophs

• first trophic level that produces its own energy

  • photo/chemosynthesis

Consumers

• Eat other organisms

• Primary Consumer: eats producers and are usually herbivores

• Secondary Consumers: eat primary consumer

• Tertiary Consumers: eat secondary consumers and are usually carnivores

Detritivores/Decomposers

• consume non-living organic matter

• Detritivores: scavenge the waste products + dead bodies of other in the community (i.e. soil insects)

• Decomposers: break down litter + non-living matter into smaller pieces that can be taken up by plants

  • enhance soil nutrients

Keystone Species

• species that have wide reaching impacts far out of proportion to its abundance - often high on the food chain

• trophic cascade = effect of one species on an ecosystem as a whole

  • can also be caused by ecosystem engineers

Disturbance

• an event that affects environmental conditions

• commmunities can

  • resist change = resistance

  • change in response but return to original state after = resilience

• If disturbance eliminates all or most of a community, the area will undergo succession

Primary Succession

• occurs when there is practically no vegetation or soil life left

• begins w/ pioneer species that is well adapted for colonization

  • lichens colonize bare rock and secrete acid that breaks down the rock surface eventually forming soil

• plants and insects come and provide more nutrient

• larger plants and animals establish themselves

• Climax community stay until another disturbance

Secondary Succession

• when disturbance does not destroy all living things in the soil, what is left of previous community helps shape the process

Phase (Regime) Shift

• overall character of the community changes

• human activity can cause this: novel/non-analog communities

Feedback Loops

• system output serves as input

• negative: output from system moving in one direction causes the system to move the other direction

• positive: increased output = increased input = even more increased output etc.

  • moves toward extreme

  • i.e. glaciers melting not being able to reflect sunlight so they get hotter and melt more

Emergent Properties

• characteristics not evident in the components alone

System interactions

• Main systems: lithosphere (rock and sediment), atmosphere (air), hydrosphere (water), and Biosphere (organisms+abiotic parts of environment)

• Energy moves in one direction

• Matter is recycled

• ecotones = transitional zones between two ecosystems

Primary Production

• autotrophs convert solar energy to chemical energy

• total amount of energy produced = gross primary production

• net primary production = gross production - respiration (energy used for cellular respiration by the plant)

• rate at which energy is converted to biomass = productivity / net primary productivity

• eaten by heterotrophs, some is used to generate biomass which becomes secondary production

Eutrophication

• super bloom of algae due to nitrogen and phosphorus increase from runoff causes decomposers to over-consume oxygen and creates a dead zone

Nutrients

• macronutrients: required in large amounts

• micronutrients: needed in smaller amounts

Hydrologic Cycle

Carbon Cycle

Nitrogen Cycle