semester 2 bio cornell note

6.3 + p158

  • struggle for existence = all populations have the potential to produce more offspring than can survive members of the population will compete for ifinite supply of environmental resources

  • Predatory w better phenotype - catch prey more

  • Prey w better phenotype - avoid being caught

  • Adaptation = Any heritable characteristic that increase an organism's ability to survive & reproduce in environment

    • phenotype

    • Physiological

      • Photosynthesis

      • Way an animal hibernates

      • Behaviors

  • Difference in adaptation affect an individual's fitness

  • Fitness = how well an organism can survive & reproduce in its environment

  • Survival of the fittest =

    • Individuals with adaptations better suited can survive & reproduce & are said to have high fitness

    • Individuals with characteristics not well suited either die without reproducing or leave relatively few offspring & are said to have low fitness

      • Result -> Differential reproductive success or survival of the fittest

  • Survival - survive and reproduce and passing good adaptations to next gen

  • Natural selection = process by which organisms in nature with variations most suited to their local environment survive & leave more offspring

  • Both artificial & natural selection, only certain individuals produce offspring

    • Natural selections the environment influences fitness

    • Artificial selection farmer or animal breeder influences fitness

  • Natural selection occurs in any situation in which

    • more individuals are born than can survive

    • natural heritable variation affect the ability to survive & reproduce or inheritable adaptations vary among individuals

    • fitness varies among individuals

      • Basically natural selection occurs in situations of struggle for existence, variation & adaptation, & differential reproductive success

  • natural selection doesnt move in a fixed direction

  • Local environmental conditions change some traits that use to be adaptive may no longer be useful & diff traits may be come adaptive

    • This can lead to great diversity of adaptations in species living in diff environments

  • Environmental conditions change faster than species can adapt to those changes the species may become extinct

  • Natural selection depend on individuals ability to reproduce & leave offspring

  • Descent with modification = living species are descended with change over time form common ancestors

  • Principle of common descent: all & living and extinct are united by descent from ancient common ancestors & exhibit diversity due to natural selection & adaptation

  • Artificial selection = selective breeding of plants & animals to promote the occurrence of desirable traits in offspring

    • Nature provides the inherited variations & humans select variants that r useful

    • selective breeding = artificial selection

  • Inherited variation could provide raw material for natural mechanism that could drive evolution

6.4

  • Biogeography = the study of past & present distribution of organisms

  • Patterns in the distribution of fossils & living species combined with info from geology tell us how modern organism evolved from their ancestors

  • Why involving biogeography important

    • Closely related species can evolve diverse adaptations in diff environments

    • Very distantly related species can evolve similar adaptations if they live in similar environments or face similar challenges in the struggle for existence

  • Discovery of radioactivity & the technique of radioactive dating enables geologists to establish the age of certain rocks & fossils

    • earth is about 4.5 billion years old

  • Homologous structure = structures that are similar in diff species of common ancestry

    • Key to identifying homology is common structure & origin during development not common function

    • Homologous structures have similar structures & development but diff functions

  • Evolutionary theory explains the existence of homologous structures adapted to diff purposes bc of descent with modifications from common ancestor

  • Similarities & diff among homologous structures help determine how recently species shared common ancestors

  • Vestigial structure = structure that is inherited from ancestors but has lost much or all of its og function

  • Analogous structures = body parts that share a common function but not structure

    • grow & develop from diff embryonic tissues

  • The same groups of embryonic cells develop in the same ogre & similar pattern to produce any homologous tissues & organs

  • Molecular homology - genes that control the development of both visible & microscopic homologous structures

  • At molecular lvl overwhelming similarities in the genetic code of all organisms along with homologous genes

  • Mutations & gene shuffling during sexual reproduction produce heritable variation on which natural selection operates

  • Molecular evidence for evolution is so basic all living cells use info coded in DNA & RNA to carry info from 1 gen to the next & direct protein synthesis

  • Ex of homologous gene is set of genes called hox genes that determine the destinies of body parts

    • Hox gene help determine which part of an embryo become the head & which part becomes tail

  • Small changes in the hox genes can produce dramatic changes in the size & shape of the structures they control

  • Relatively minor mutations in an organism genome can produce major changes in an organism structure & the structure of its descendants

  • Variation within species increases a population ability to adapt to & survive environmental change

  • Evolutionary theory is vital to all biological & biomedical sciences often called the grand unifying theory of the life science

13.1

  • Heritable traits are controlled by genes carried on chromosomes

  • Changes in gene & chromosome generate variation

  • Molecular genetic techniques test hypothesis abt variation & selection

  • Genes, population, & species

  • Species = is a population ( or group of population) of physically similar interbreeding organism that dont interbreed with other groups

  • Population = group of individuals of the same species that mate & produce offspring

  • Bc interbreed they share common group of gene

  • Gene pool = all the genes including diff alleles for each gene that are present in a population at any one time

  • Allele frequency = the number of times that an allele occurs in a gene pool compared with # of alleles in that pool for the same gene

    • Basically the # of times an allele occurs in a genepool as a percentage of total occurrence of alleles for that gene in that gene pool

  • Evolution involves any change in the frequency of alleles in a population over time

  • Natural selection can act by increasing or decreasing the relative fitness of individual organism

    • Individuals dont evolve during their life time

  • Result of natural selection show as changes in allele frequency in population over time

  • natural selection “selects” an entire organism either to survive & reproduce or die without reproducing

  • Genotype = the combo of alleles an individual

  • Phenotype = all physical physiological & behavioral characteristics of an organism

  • Natural selection acts directly on organism's phenotype not genotype

    • Phenotype made by Individuals genotype tgt w environmental conditions during its lifetime

  • Some individuals have phenotypes that are better suited to their environment

  • Higher fitness = produce more offspring & pass more copies of their genes to the next gen

  • Inherited variation can lead to natural selection bc result in diff reproductive success

  • Evolutionary adaptation is any genetically controlled traits that increases an individual's fitness

Sources of genetic variation

  • Genetic variation is produced in 3 main ways

    • Mutation

    • Genetic recombination during sexual reproduction

    • Lateral gene transfer

Mutations

  • Genes are duplicated & passed from 1 gen to next without change

    • Sometimes mutations is a heritable change in genetic info

  • Mistakes in DNA replication are actually essential to species long term survival

  • Population where DNA replicates flawlessly producing new gen without genetic change would lack much variation on which natural selection operates

  • Environments changes , population that cant evolve dont survive long

  • Neutral mutations = dont affect phenotype & dont affect fitness

  • Mutations that do produce changes in phenotype may or may not affect fitness

  • Some mutations may lower fitness by decreasing an individual's abilities to survive & reproduce

  • Other mutations may result in adaptation that improve individuals abilities to survive & reproduce

  • Mutations matter in evolution only if they can be passed from gen to gen

  • For mutation to happen in plants & animals mutations must occur in gametes

  • Most heritable diff within families caused by genetic recombo

  • During meiosis, 1 member of each chromosome pair is shuffled randomly into each egg or sperm w 1 member of every other chromosome pair

  • Human have 23 pairs of chromosome

  • Can produce 8.4 million gene combinations

  • Crossing over another mechanism that can produce genetic recombo

  • Crossing over - meiosis paired chromosomes often swap length of DNA at random

    • Increase # of new genotype created in each gen

  • Genes are passed oneself from parent to offspring during reproduction

  • Sometimes gene pass from 1 individual to another individuals that is not its offspring

  • Lateral gene transfer = passing of gene produces a kind of gene flow

    • Occur between individuals of the same species or individuals of diff species

  • Gene flow can increase genetic variation -> increase diversity in any species that picks up new genes

  • Lateral gene transfer among single celled organism common & important in generating diversity among species during history of life

  • Sometimes single gene produces a simple trait

  • Number of phenotypes produced for traits depend on how many genes control the trait

  • Traits control by single gene may have only 2 or 3 distinct phenotypes depending on # of alleles

  • Single gene trait = trait controlled by 1 gene that has 2 alleles

  • In population phenotypic ratio are determined by frequency of alleles in the populations as well a whether the alleles are dominant or recessive

  • Polygenic trait = trait controlled by 2 or more genes

    • Each gene of a polygenic traits often has 2 or more alleles

  • Single polygenic trait often has many possible genotype & even greater variety of phenotype

    • Height in humans is polygenic trait bc it varies from small to tall

  • Symmetrical bell- like shape of curve is typical of polygenic traits

  • Bell Shaped curve = normal distribution

  • This graph show distribution of phenotype that would be expected for a trait if any genes contributed to trait

13.2

How natural selection works

  • Insecticide or antibodies introduce:

    • Compounds become part of environment

    • Reduce fitness of any individual susceptible to their effect

    • Some individuals in pest population carry 1 or more genetic variation that enable them to resist

  • Few america carry genetic variation that lets them resist antibodies

    • Both kind of resistance are adaptation that enable individuals to survive & reproduce

  • Presence of pesticide or antibiotic increase the relative fitness of the few individuals that carry the resistance adaptation

  • Resistant individuals survive & thrive bc dramatically reduce d population (less competition for resources)

  • Over time the frequency of resistance alleles increase in the population

  • Natural selection - Diff survival & reproduction of individuals with beneficial characteristics

  • Natural selection on single gene traits can produce changes in allele frequencies that may be reflected by simple changes in phenotype frequencies

    • Can lead changes in allele frequencies so thus to evolution

  • A trait is controlled by more than 1 gene both the traits & the effects of natural selection on the trait are more complex

  • Polygenic traits often display range of bell curve

  • Fitness of individual may vary from 1 end of such survival to the other & natural selection can act 1 of 3 ways

  • Natural selection on polygenic traits can affect the relative fitness of phenotype in 3 types of selections

    • Directional selection

      • When individuals at 1 end of the curve have higher fitness than individuals elsewhere in the curve

      • Range of phenotype shift bc individuals with adaptations that result in higher fitness experience higher reproductive success

    • Stabilizing selection

      • Individuals near the center of the curve have higher fitness than individuals at either end

      • Center of curve remains current position but curve overall become narrow

    • Disruptive selection

      • Phenotypes at both the upper & lower end of curve have higher fitness than individuals near middle

      • Lowers fitness of intermediate phenotypes

      • If pressure of natural selection strong & longs enough curve can split

        • Making 2 distinct phenotypes created increasing diversity

  • In small populations individuals that carry a particular allele may leave more descendant than other individuals just by chance

  • Over time series of chance occurrences can cause an allele to become more or less common in population

  • genetic drift= random change in allele frequency caused by series of chance that cause allele to become more or less common

  • Genetic drift can occur by bottleneck effect & founder effect

    • Bottleneck effect= a change in allele frequency following a dramatic reduction in the size of a population

    • Founder effect= change in allele frequency as result of the migration of a small subgroup of a population

  • Genetic equilibrium = situation in which allele frequencies in populations remain the same

  • Meiosis & fertilization by themselves do not change allele frequencies

  • Population of sexually reproducing organisms could remain in genetic equilibrium

  • Hardy weinberg principle= that allele frequencies in a population remain constant unless 1 or more factors cause those frequencies to change

  • Hardy weinberg principle predicts 5 conditions can disturb genetic equilibrium & cause evolution

    • Nonrandom mating

      • sexual selection= individuals select mates based on heritable traits

        • When occur genes for traits selected for or against are not in equilibrium

    • Small population size

      • Genetic drift does not usually affect large populations

    • Gene flow from immigration & emigration

      • Gene flow = the movement of genes into or out of a population

      • Individuals that join through immigration may introduce new alleles

      • Individuals that leave through emigration may remove alleles

      • If allele frequency in population changes gene flow has caused evolution to occur

    • Mutations

      • Can introduce new alleles into gene pool changing allele frequencies

    • Natural selection

      • If genotype have diff fitness natural selection will disrupt genetic equilibrium

13.3

  • speciation= formation of new species

  • Interbreeding enables any genetic change that occurs in a population to spread throughout that population

  • If 2 populations stopped interbreeding change in 1 gene pool could not spread to other

  • reproductive isolation= separation of a species or population so that they no longer interbreed & evolve into 2 separate species

    • Can develop in several ways

      • Behavioral isolation = form of reproductive isolation in which 2 populations develop diff behaviors that prevent them from breeding

        • If 2 populations that were once able tgt interbreed evolve diff then this would occur

      • Geographic isolation= 2 populations are separated by geographic barrier leading to the formation of 2 separate subspecies

        • When 2 populations are separated by geographic barrier

        • Geographic barriers dont always guarantee isolation

      • Temporal isolation= 2 or more species reproduces at diff times

  • Biological island - any habitat that is isolated in some way from other similar habitats

Speciation in darwin's finches

  • Speciation in galapagos finches occurred by:

    • Founding of new population

      • Allele frequencies of founding finch population could have differed form allele frequencies from og populati9on

    • Geographic isolation

      • Some combo of founder effect geographic isolation & natural selection resulted in diff reproductive success adaptations & evolutions

      • Bc of diff island the finch populations were geographically isolated & no longer shared a common gene pool

    • Changes in the new population gene pool

      • Finch went to diff island but that island food was smaller so those finches adapted to having smaller becks

      • Over times natural selection would have caused the population to evolve smaller beaks forming new population w new phenotype

    • Behavioral isolation

      • Finches preferred to mate w bird that have same size beak so they did not want to mate with other population

      • The gene pool of the 2 birds population live in same place but population now become 2 distinct species

    • Ecological competition ( competition & continued evolution

      • As 2 new species live tgt they compete for seeds

      • During diff seasons birds that are most diff from each other have higher fitness bc more specialized bird experience less competition for certain kind of seed

8.1

  • Nebula -> heat up & rotate -> cooled -> repeat & collide w other things = planets

  • Crust = thin layer of rock that forms earth's outer surface on land & in ocean

  • Lithosphere = sphere made up of hard rock on & just below earth's surface (the outermost layer of both earth & geosphere

  • Mantle = layer of very hot but mostly solid rock beneath earth crust

  • Core = layer of earth below mantle (rllllllllly hot)

  • Earths early atmosphere contained little or no oxygen

    • Main composed of CO2, water vapor, nitrogen, smaller amount of carbon monoxide, hydrogen sulfide, hydrogen cyanide

      • Earth cool make water vapor rain -> earth cooler

  • Lithosphere divided into huge plates that each include vary amount of continental & oceanic crust

  • Plate tectonics= geologic process resulting in plate movement

  • Theory of plate tectonic explain how & why earth lithospheric plate move relative to each other

    • Result convection currents in earth mantle

  • Upwelling current in mantle bring hot rock to surface

  • Hot rock metals to form magma creating new crust at mid ocean ridges

    • Youngest crust in center where plates diverge

    • Heat of magma at mid ocean ridges creates hydrothermal vents

  • Older crust sink to mantle subduction zone heated releases water & partially melt

  • Melting crust rises to surface leading to volcanic eruption

  • Hotspot = volcano created by plume of magma rises to

  • 2 plates carrying continents collide -> part of lithosphere contain oceanic crust sinks into mantle

  • Part of colliding lithospheric containing continental crust cant sink so collide & get forced into each other

  • Many interactions between the geosphere atmosphere & hydrosphere break down or chemically change rock at or near earth's surface

  • Weathering = physical & chemical process that break down rock & mineral into smaller particles

    • Water enter rock & freezes it expand -> expansion can break rock into smaller & smaller

    • 2 types of weathering

      • Chemical weathering = Occurs when water or chemically active molecule in rain transform compounds in rock or other material

      • Physical weathering breaks up rocks & wears them down in diff ways

  • Erosion - after rock have broken down small particles carried by wind water or ice

    • + some compounds formed or released by weathering can dissolve in water & carried either into ground or through river & streams to lakes & oceans

  • Small particles of sand silt clay or lime carried by streams or rivers reach larger body of water

    • Pressure & chemical process compress & transform sediment into sedimentary rocks

  • Examining and comparing rock layers exposed at diff places across landscape geologist can determine the order in which those rock layer formed & which layers are older than others

  • Relative dating = method of determining the age of fossil by comparing its placement with that of fossil in other rock layers

  • Sedimentary rock formed as layers

    • Lower layers of rock & fossil contain generally older than upper layers

  • Index fossil= distinctive fossil aht used to compare the relative age of fossil

    • Must be easy to recognize

    • Only existed for brief span

    • Widely distributed

  • Radiometric dating= method to determine age of sample from amount of radioactive isotopes to the nonradioactive isotope of the same element

  • Half life = length of time required for half of the radioactive atoms in a sample to decay

  • Radiometric dating uses the proportion of radioactive isotopes & stable isotopes to calculate age of sample

  • Age determined by amount of carbon 14 remaining in tissues

  • Carbon 14 half life if to old cant be seen anymore

  • Older fossil that cant be dated using isotopes

    • Use potassium 40, etc

  • Geologic time scale = timeline used to represent earth's history

  • Geologic time scale based on both relative & absolute dating

  • Major divisions are

    • Eons

    • Eras

    • Periods

8.3 & p224

  • Distribution of continents & oceans determined by plate tectonics formation of islands global climate change & meteorite impacts have altered earth's habitat with major effects

  • Environmental changes altered ecological interaction among organism & between organism & their environments

    • Change the pressures of natural selections favoring adaptations to new conditions

    • Emergence of new habitat & changes in existing habitats create new niches

      • New niches - offer opportunities for natural selection to increase diversity

  • Regional & global environments are influenced by interactions between wind & ocean currents

  • Slow movement of continents due to forces of plate tectonics produced even more dramatic changes in global landscape

  • Over deep time actions of living organism have changed conditions in the atmosphere ocean & land

  • Macroevolutionary pattern= changes in anatomy, phylogeny, behavior that take place in clades larger than single species

  • Emergence growth & extinction of larger clades are macroevolutionary

  • Fossil species are classified using same cladistic techniques used to classify living species

  • Cladograms illustrate hypothesis about how closely related organism are by proposing relationships among living, extinct pieces, & common ancestors they share

  • Hypothesizing that extinct species is related to a living species not same thing as claiming that extinct organism is ancestors of living species

  • Environmental condition change natural selection & other evolutionary mechanisms enable some species to evolve adaptations to new conditions

  • Extinct = refer to a species that has died out & has no living members

  • Background extinction = extinction caused by slow & steady process of natural selection

  • High species diversity in clade serve as raw material for macroevolutionary change in that clade

    • More varied adaptations of species in clade are the more likely the clade is to survive

  • Rate of speciation in clade = or > rate of extinction = clade will continue to exist

  • Rate of extinction in clade > than rate of speciation= clade will eventually become extinct

  • Mass extinction = event during which many species become extinct during relatively short period of time

    • Large number of species become extinct relatively short time

    • Become extinct bc environment break down & ordinary process of natural selection cannot compensate quickly enough

    • Reduce biodiversity rapidly & dramatically

  • After mass extinction

    • Less competition

    • Climate may have changed

    • New ecological niches open up

    • Adaptations & speciation produce new species that fill those niches

      • Biodiversity recovers slowly

  • Fossil evidence supports hypothesis that evolution can occur at diff rates in diff clades at diff times

  • Fossil record incomplete bc every organism as fossil many more die without a trace

  • Fossil reveal info abt

    • Structure of ancient organism

    • Sequential nature of groups in fossil record

    • Evolution from common ancestors & the ecology of ancient environments

  • Gradualism = evolution of a species by gradual accumulation of small genetic change over long period of time

  • Sometimes physical structure preserved dont appear to change much over long period of time

  • State of equilibrium - their structure dont change much even though they continue to evolve

  • Slow steady change in line of descent

  • Fossil record show that equilibrium can be interrupted by brief period of geologically rapid change

  • punctuated equilibrium= pattern of evolution in which long stable period are interrupted by brief period of more rapid change

  • During punctuations existing species may change & new species may appear rapidly

  • Stable period interrupted by rapid change

  • Rate of change: genetic drift & mass extinction

  • Small population

    • Trait can become more or less common by chance

  • Rapid evolution may occur after small population become isolated from main population

  • Adaptive radiation= single specie or small group of species evolves into several diff forms that live in diff way

  • Descendants of ancestral species may diversify over time into related species adapted to diff niches

  • Adaptive radiation may occur when species migrates to new environment or when extinction eliminates competing species

  • Convergent evolution= unrelated organisms independently evolve simialties when adapting to similar environments

    • Unrelated organism in similar environment evolve adaptations to similar niches

  • Coevolution = 2 species evolve in response to changes in each other over time

  • Relationship between coevolving organism often become so specific that evolutionary change in 1 organism usually followed by a change in other organism

1.1

  • Biosphere = part of earth in which life exist including land water & air or atmosphere

  • Ecology = study of interactions among organism population & communities of organisms effects on their environment & their responses to changes in their environment

  • lvls of ecological organization

    • Individual (species)

      • Group of similar organism that can breed & produce fertile offspring

    • Population

      • Group of individuals that belong to same species & live in same area

    • Community

      • Assemblage of diff populations that live tgt in defined area

    • Ecosystem

      • abiotic & biotic factors

    • Biome

    • biosphere

  • Biotic factors = any living part of environment with which an organism might interact

  • Abiotic factors = physical or nonliving factor that shape an ecosystem

  • Earths 4 global spheres:

    • Atmosphere: all gases thin layer of gases that surround earth

    • Hydrosphere: all water. Liquid ice or vapor EVERYWHERE

    • Geosphere: all the rock EVERYWHERE

    • Biosphere: part of earth in which life exists including land, water, & air or atmosphere

      • Earth's systems interact w 1 another & cause & effect of global changes involve all of the systems

1.2

  • Weather = day to day condition of atmosphere (short term changes)

  • Climate = average year to year conditions of temperature & precipitation in area over long period of time

    • Both shape natural populations communities & ecosystems

  • Earth global climate system powered & shaped by total amount of solar energy retained in biosphere as heat & by unequal distribution of that heat between the equator & poles

  • Earth average temperature determined by balance between amount of heat that stays in atmosphere & amount of heat that is lost to space

  • Greenhouse gases

    • Carbon

    • Methan

    • Water vapor

      • These gases enter & leave atmosphere as part of cycle

  • Greenhouse effect = process in gases (carbon, methane & water vapor) trap sunlight energy in earth's atmosphere as heat

  • increase greenhouse gas = retains more heat & earth warms

  • decrease greenhouse gas = more heat escapes & earth cools

  • Amount of sunlight that is reflected or absorbed- amount of heat that is reradiated in earth system & intensity of greenhouse effect influence earth energy balance

  • 3 main climate zone

    • Tropical

    • Temperate

    • Polar

  • Unequal heating of earth's surface creates winds & ocean currents

  • Hot air = less dense & rises

  • Cold air = more dense & sinks

    • Air rises - loses heat along way

  • Rising & sinking air creates circulation of air that rises -> creates winds

  • Ocean currents are driven & shaped by patterns of warming & cooling by winds & location of continents

  • Prevailing winds blowing over ocean create surface currents affecting weather & climate

  • Upwelling - water sinks flow along sides & rises to surface

    • Move cold water to top & hot to bottom

  • Regional climate shaped by transport of heat & moisture by wind & ocean current & by geographic features

  • Upwind side of mountain ( near the ocean)

    • Air rises & cools releasing moisture as rain or snow

  • Downwind side of mountain

    • Air descends & warm & drier so less rain falls

3.1

  • Autotrophs = organism that able to capture energy from sunlight or chemicals & use it to produce its own food

    • Convert energy into forms living cells can use

  • Primary producer = first producers of energy rich compounds that are later used by other organisms

    • All life depend on 1 or another kind of primary producer

  • Photosynthesis = used by plants & autotrophs to capture light energy & use it to power chemical reactions that convert carbon & water into oxygen & energy rich carbohydrates (sugars & starches)

  • chemosynthesis= process in which chemical energy is used to produce carbohydrates

    • Chemosynthetic bacteria thrive

      • deep in earth crust

      • Total darkness

      • Exposed to hecka high temps

  • Heterotrophs = organism that obtain food by consuming other living things

    • Heterotrophs = consumers

  • Consumers = organism that relies on other organism for its energy & food supply

    • Consumers are organism that rely on other organism for energy & nutrients

  • Diff types of consumers:

    • Carnivores - meat

    • Herbivores - plants

    • Scavengers - carcasses

    • Omnivores - meat & plant

    • Detritivores - commonly digest decomposer that live on & in detritus particles

      • Detritus: material made up of decaying bit of plant & animal material

    • Decomposer: chemically breaks down the organic matter back into their elemental form

      • Convert dead material to detritus then eaten by detritivores

      • Release matter in form of nutrients for primary producers

      • 2 main decomposers: Bacteria & Fungi

3.2

  • Energy flows through an ecosystem in 1 way direction

  • Food chain = series of steps in ecosystem in which organism transfer energy by eating & being eaten

  • Phytoplankton = photosynthetic algae found near surface of ocean

    • Eaten by zooplankton

  • Food web = network of complex interactions formed by feeding relationships among various organism in ecosystem

    • Bunch of food chains that connects

  • Trophic lvl = each step in food chain or food web

    • Producer 1st lvl of trophic lvl

  • Ecological pyramid = model of relative amounts of energy or matter contained within each trophic lvl in given food chain or food web

  • 2 diff types of ecological pyramid

    • Energy pyramid

      • show relative amount of energy available at each trophic lvl of food chain or food web

    • Biomass pyramid

      • Relative amount of living organic matter in each trophic lvl of ecosystem

    • Number pyramid

      • Relative number of individual organism at each trophic lvl in ecosystem

  • Only small portion of energy stored in any trophic lvl available to organism in next lvl

    • Bc organism use the energy for life processes

    • 10% of energy available in 1 trophic lvl to next

  • Biomass = total amount of living tissues within given trophic lvl

    • Measured organic matter per unit area

3.2

  • Elements are recycled within & among ecosystem through cycles that may involve:

    • Biosphere

    • Geosphere

    • Hydrosphere

    • Atmosphere

  • Biogeochemical cycle = element chemical compound & other forms of matter are passed from 1 organism to another & from 1 part of biosphere to another

    • Powered by flow of energy

  • Biogeochemical cycles:

    • Biological process- activities performed by living organisms

      • Mainly occur in biosphere but involve all 3 spheres

    • Geological process- rocky earth stuff (volcano, formation & breakdown of rock & movement of matter

      • Mainly in geosphere but also affect 3 other spheres

    • Physical & chemical process- cloud form, precipitation, flow water

      • Primarily hydrosphere atmosphere & biosphere but also affect biosphere

    • Human activities- big & small scale

      • Change system in 4 sphere

  • Water cycle among hydrosphere, atmosphere, & geosphere sometimes out & in biosphere

  • Carbon nitrogen & phosphorus cycle important part of several global systems & vital to function of ecosystem

  • Carbon reservoir = natural feature that stores carbon

  • Nitrogen fixation = converting nitrogen gas -> nitrogen compound that plant can use

  • Denitrification = bacteria convert nitrate -> nitrogen gas

  • If ample sunlight & water are available primary productivity of ecosystem may be limited by availability of nutrients

  • Limiting nutrients = single essential nutrient that limit productivity in ecosystem

22.1

  • Habitat = area where organisms live including biotic & abiotic factor that affect it

  • Habitat can be described as an area with particular combo of biotic & abiotic factors that affect which organism can live within it

    • Organisms ecological “address”

  • Microhabitat - many small organism live only in very small part of larger habitat

  • Microclimate = environmental conditions in microhabitat

  • Mircobiome or microhabitat perform more important functions

  • Tolerance = ability of organism to survive & reproduce under circumstance that differ from their optimal condition

    • Optimum range is environmental conditions enable individual to

      • find enough energy

      • Nutrient to maintain homeostasis

      • Grow & reproduce

  • Stress - 1 or more environmental condition rise above or fall below optimum range

  • Stressed

    • Expend more energy to main homeostasis

    • Leave less energy for growth & reproduction

  • Slightly stressed

    • Produce fewer offspring

      • Fewer of those offspring will survive

  • HECKA stressed

    • May survive but not reproduce

  • Niche = full range of physical & biological condition in which an organism live & the way in which organism uses those condition

    • Where organism live & what it does ( ways it interact with biotic & abiotic factors

    • Physical aspects

      • Factors to which it is adapted

    • Biological aspects

      • Factors it require for survival

  • Species niche: range of physical & biological condition in which it can survive 7 reproduce & obtain resources it needs

  • Resources = any necessity of life

  • Competition - competing for resources

    • Intraspecific competition- among member of same species

    • Interspecific competition - between members of diff species

  • Direct competition -> 1 winner 1 lose & losing species die out

  • Species grown in separate culture under same condition = survived

  • Both species grown tgt in same culture 1 species outcompeted other

    • Less competitive species die

  • Competitive exclusion principle = states that no 2 species can occupy the same niche in same habitat at same time

    • Creates pressure for each species to specialize in way that it obtains & uses resources

  • If 2 species try 1 species will be better at competing for limited resources & eventually exclude other species

  • Division of resources - resources used by species are similar but not identical each species occupy a diff portion of area

  • By causing species to divide resources competition help determine number & kind of species in community & niche each species occupy

  • Herbivores affect size & distribution of plant population in community & determine place that certain plants can survive & grow

  • Keystone species = single species that not usually abundant in community yet exerts strong control on structure of community

  • Keystone species play vital & unique role in maintaining

    • Structure

    • Stability

    • Diversity in ecosystem

  • Removal of keystone species - may or may not be possible to restore OG community by putting it back

  • Symbiosis = relationship in which 2 species live close tgt

  • 3 main type of symbiotic relationship

    • Commensalism = 1 organism benefit & other neither helped or harmed

    • Mutualism = both species benefit

    • Parasitism = 1 organism live on or in another organism & harms it

      • Obtain all or part of nutritional need form host

      • Generally weaken but not kill host

22.2

  • Ecological succession = series of gradual changes that occur in community following a disturbance

  • Ecosystems change over time especially after disturbances

    • New species move in

    • Population change

    • Some species die out

  • Primary succession = succession that occur in area in which no trace of previous community is present

  • Pioneer species = 1st species to populate an area during succession

    • Have broad range of tolerance

    • Usually lichens

  • Secondary succession = succession the occur in area that was partially destroyed by disturbances

    • Faster than primary bc old parts of community still survive & can regrow fast

  • Each species alters its environment in way to make it ez for other species out compete for resources & survive

  • Some processes increase the complexity of environment enabling more plants & animals species to find home & food

  • Natural disturbances happen in healthy ecosystems the event & processes that occur during secondary succession often( not always) reproduce OG climax community

  • Secondary succession can take diff paths & produce diff communities depending on

    • kind of disturbance

    • Season in which disturbance occur

    • other factors

  • Early stages of primary succession are slow & chance can play big role in determining which species colonize at diff times

1.3

  • Biomes = group of ecosystem that share similar climate & typical organism

  • Biomes described in term of abiotic factors & biotic factors

  • Anthromes = ecological region created by long term interaction between human & ecosystem

  • Aquatic ecosystem are described primarily by

    • Salinity

    • Depth

    • Temp

    • Flow rate

    • Concentration of dissolved nutrients

  • 2 main group of aquatic ecosystem

    • Marine ecosystem

    • Freshwater ecosystem

    • Estuaries

  • Open ocean- literally ocean ocean

    • Has 2 main zone of light penetration

      • Photic & aphotic zone

  • Photic zone = region near surface in which photosynthesis occur yes sunlight

  • Aphotic zone = dark layer of ocean below photic zone where no sunlight

    • Organism exposed to high pressure frigid temps & total darkness

    • Supported by deep sea vents based on chemical energy

  • Intertidal zone - submerged in seawater at high tide & exposed air & sunlight in low tide

    • Typical rocky intertidal community in temperate region exposed rock line the shore

    • Experience regular & extreme changes in temp & often battered by wave & current

  • Coastal ocean - extends low tide mark to outer edge of continental border

    • Water brightly lit & often supplied with nutrient by freshwater runoff

    • Highly productive

  • 3 main categories of freshwater ecosystems

    • Rivers & streams

      • Originate from underground sources in mountain or hills

      • Near source: high dissolved oxygen low plant life

      • Downstream: increased sediment & plant growth

      • Hecka downstream: water meander through flat area

      • 1 way directions

    • Lakes & ponds

      • Depend on combo of plankton & attached algae & plants

      • Water flow in & out via rivers or streams

      • Upwelling of heat oxygen & nutrients

      • 1 way direction

    • Freshwater wetlands

      • Nutrient rich & highly productive

      • Breeding ground for many organism

      • Purify water by filtering pollutant

      • Prevent flooding by absorbing & slowly releasing large amounts of water.

    • Wetland = ecosystem in which water either cover the soil or is present at or near surface for at least part of year

  • Estuary = kind of wetland formed where river meet ocean

    • Serve as spawn in & nursery ground for many ecologically & commercially important fish & shellfish

    • Salt marsh - temperate estuaries bc salt tolerant grasses above low tide line & seagrass below water

    • Mangrove swamp - tropical estuaries bc several species of salt tolerant tree (called mangroves lol)

2.1

  • Ecologists study populations by examining:

    • Geographic range

    • Growth rate

    • Density & distribution

    • Age structure

  • Geographic range or population range - places a population lives

  • Population density = number of individuals per unit area

    • How number are in area

  • Diff species can have diff densities in same environment

  • Population distribution = describes way individuals are space out across their range

    • How they are spread out in area

  • 3 main distribution patterns

    • Random - location of individuals is independent of other individuals

    • Uniform - individuals compete with 1 another for space or other resources

    • Clumped - clumping to help individuals

  • Age structure: number of males & females of each age in population

    • Important bc

    • most plant & animals cant reproduce until certain age

    • animals only female can produce offspring

    • number of offspring they produce vary with age

  • Birthrate deathrate & rate at which individuals enter or leave population all affect population growth

  • Population increase = birthrate > deathrate

    • Birth mean diff things in diff species & spiecies vary in amount of young produced

    • immigration

  • Population stay same = birthrate = deathrate

  • Population decrease = Deathrate > birthrate

    • emigration

  • Immigration = movement of individuals into

  • Emigration = movement of individual out

  • Exponential growth - Population increase more & more rapidly as more & more offspring made

    • J shaped curve

    • Presences of unlimited resources

    • Absence of predation & disease

  • Lots of offspring & gens - > why rate of population growth changes even though birth rate more or less constant

  • Under ideal condition w unlimited resources a population will increase exponentially

    • Means that larger population get faster grows

  • Logistic growth = growth pattern in which population growth slow & then stop following period of exponential growth

    • S shaped curve

    • Resource become limited

    • Population growth slow or stop

    • Leveling at carrying capacity

  • Logistic growth phases:

    • Phase 1 - population grow rapidly

      • Individual grow & reproduce lots

    • Phase 2 - growth slow down

      • Doesn't mean population size decreases

    • Phase 3 - growth stop

      • Population growth drop -> 0

      • Population size levels off

  • Stable growth = combo of birthrate + deathrate + immigration + emigration = 0

  • Carrying capacity = largest number of individuals of particular species that a particular environment can support

  • Population reach carrying capacity = stabilizes if environmental condition r kinda constant

2.2

  • Limiting factor = factor that causes population growth to decrease

    • Are interactions between members of population & either biotic or abiotic factors

      • Some interaction depend on population density

      • Other interaction act in more or less same way regardless of population density

  • Acting separately or tgt limiting factors determine the carrying capacity of an environment for species

  • Often limiting factor keep most population in natural habitat at a population size between extinction & overrunning ecosystem

  • Long term population growth & species survival often depend on limiting factors

  • 2 types of limiting factors

    • Density dependent limiting factors = limiting factor that depend on population density

    • Density independent limiting factors = limiting factor that affect all populations in similar way regardless of population density

  • Density dependent limiting factor:

    • Competition - competing for resources & more individuals that there soon use up the resources

      • Can decrease birthrate

      • Increase deathrate

      • Or both

      • Occur among members of diff species that attempt to use similar or overlapping limited resources

    • Parasitism & Disease - weaken hosts & causes stress or even death & more dense host population more easily can spread to diff hosts

    • Stress from overcrowding - weakens body ability to resist disease & species fight amongst themselves

      • Can lower birthrate

      • Raise deathrate

      • Or both

      • Increase rate of emigration

    • Predation

      • Population of predator & prey may rise or fall

        • Prey increase = easy prey for predators

        • Predator increase = predator kill more than born

          • Prey decrease = deathrate > birthrate

        • Prey decrease = predator rises deathrate & lower birthrate = predator decrease

    • Herbivory - eating to many of 1 plant

      • Lwk like predator prey but prey is plant

  • Density independent limiting factors:

    • Environmental extremes

    • Natural disasters

      • Population may crash then population may build up again quick or stay low

  • Artificial density independent - control measures by human

  • If carrying capacity falls low enough species can be extinct