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GWU / Biology / BISC 1006 / Is a search for knowledge of the natural world?

Is a search for knowledge of the natural world?

Is a search for knowledge of the natural world?


School: George Washington University
Department: Biology
Course: Ecology and the Evolution of Organisms
Professor: Tara scully
Term: Winter 2015
Tags: Biology: Ecology and Evolution
Cost: 50
Name: Midterm Study Guide
Description: Test is this Thursday.
Uploaded: 03/07/2017
20 Pages 39 Views 3 Unlocks

Date of Exam: March 9, 2017

Is a search for knowledge of the natural world?

Midterm Study Guide 

● Look at the PDF of the slideshows on BB with concept questions that might be on exam ● The Nature of Science and the Characteristics of Life

○ Misconception 1: people think science is a collection of facts

■ Reality: science is a search for explanation of the NATURAL WORLD ■ Science is fluid and relies on 3 pillars (order, explain and achieve)

a. Science is ever changing and tested constantly

○ Misconception 2: scientists are always right and are unbiased

■ Reality: scientists are HUMANS and are limited by current technology a. Ex: Andrew Wakefield’s study “proved” that vaccines caused Don't forget about the age old question of How does the evolutionary perspective explain human behavior?

autism changing public opinion (study FLAWED AND

What are the three pillars of science & technology?


b. Autism rates increased but several other reasons other than

vaccines are not diagnosed before, technology, older parents, diet

and environment)

c. Biggest factor was that in 1990s the definition was expanded so

more people included

○ Misconception 3: science is a foreign language

■ Hypothesis: EDUCATED GUESS of natural world

a. Use scientific method to test hypothesis can support or reject

b. SUPPORT TRUE- needs to be tested, CORRELATION IS NOT


■ Theory: WELL-SUPPORTED explanation, lots of tests show relationship a. Few causations because limited a lot

Is a hypothesis an educated guess?

■ Science see genetically modified organisms when you select certain factors over another (NOT NATURAL BUT HUMAN)- public doesn’t see this term as the same thing

a. Scientists think DNA being inserted as genetically engineered We also discuss several other topics like How do child rearing practices differ across cultures?


■ Public often has different definition for same terms than scientists

a. Causes misunderstandings between science and common


○ Why should we care about biology?

■ Learn of self

■ Other organisms help us survive and feel better

■ Important for diet and daily life

■ Help with technology

○ Hypotheses are tested:

■ Through observational studies- need to look at specific variables related to observation, look at data to find correlation that might be causation


a. Ex: look at American and Mediterranean diet and seen effect of fish

■ Through experimental studies- look at experimental and control groups with independent and dependent variables, experiments might have conflicting results at different studies, due to having too many variables We also discuss several other topics like What is the central theoretical element?

a. Ex: genetics, age, environment, past health, current health and stress)

○ Limits to scientific method:

■ Useful for studying natural world (not spiritual or supernatural) ■ Can’t make moral judgements

■ Disapprove/prove faith-based beliefs

■ Determine personal aesthetic values

○ Organism: an individual unit which contain ALL features of life ■ Due to a common ancestors

○ ALL life is cell-based: calls are independent unit with barrier from outside so can control inside and exclude outside, ALL CELLS HAVE DNA

■ Viruses have DNA or RNA but NO CELL so not organisms

○ Cell: smallest unit; has barrier to rest of world (cell membrane) with fatty center that isolates cell We also discuss several other topics like What is the divine role of women?

■ DNA can be found in cell that hold instructions

○ All organisms have to be able to:

■ Reproduce to pass on DNA: produce offspring

a. Individuals, in evolution, don’t matter without offsprings

b. Types of reproduction:

1. Asexual reproduction: parent cell makes copy of self to

make two daughter cells

a. Each daughter cell have old and new DNA so

different from original

2. Sexual reproduction: combining egg and sperm from If you want to learn more check out What is the meaning of spinoza?

different individuals

a. Related to evolution because environment will

influence way offspring will differ from parents

(important to have LOTS of individuals so some

might have advantage and adapt)

b. Helps have more variation

■ Grow and develop

a. Bacteria also grow and develop in smaller level than multicellular organism

■ Maintain homeostasis

a. Homeostasis: able to control what is occurring inside

b. Bacteria have more simple homeostasis, multicellular organisms have more complex homeostasis

■ Responds to outside

a. Bacteria are able to communicate with one another to control pace of reproduction so won’t run out of resources

■ Take in, store and use energy

a. Organisms need to acquire energy to maintain themselves; some can use sun to get energy (photosynthesis), without producers Don't forget about the age old question of What are the salem witch trials?

other would not survive

■ Ability to evolve over time

a. Organisms evolve over time as group NOT AS INDIVIDUAL, reason why need to have offspring is because only way to evolve is for different traits to be passed down generations and spread in population

b. Individuals change fast, populations evolve slowly

○ What is species?

■ Species: group of interbreeding organisms and produce fertile offspring a. Problem because don’t account for asexual organisms

■ Evolution: characteristics of species/groups changing over time ○ History of life:

■ The Big Bang: singular thing smaller than atom EXPLODED and all things came from that- during explosion small units coming together to make bigger things (atoms are made-molecules-etc.)

a. 13.7 billion years ago

b. All things come from same materials

■ Earth formed 4.6 billion years ago, life began 3.8 billion years ago a. Up until development of sexual reproduction things slow because less diversity helping evolution

○ Fossils: remnants of past- imprints or legit remnants

■ Most due to sedimentary rock being laid on top of dying organisms ■ Not many older fossils because soft tissue decomposes and bones get mashed

○ Carbon dating: radioactive forms of carbon that aren’t stable and undergo decay as time goes on

■ Know specific percentage of atom on Earth and know what different decay rates so find fossil measure radioactive atom and see how much is missing

■ Organisms use both stable and unstable atoms

■ Can also carbon date the materials around the fossil to confirm ○ Two major cell types:

1. Prokaryotes:

a. Bacteria

b. Archaea

2. Eukaryotes

a. Anamalia

b. Plantalia

c. Fungi

d. Protist

○ Evolutionary context: relations based on observation and data

■ Broad levels: general features are similar

■ Narrow groups: all features are similar

○ 3 domains:

1. Bacteria: resemble more ancient form of life, have many nutritional


a. Prokaryotes: single-celled, microscopic, reproduce asexually

b. Reproduce quickly and evolve fast so becoming resistant to


2. Archaea: more advanced cell structure, no pathogenic, extremophiles 3. Eukaryotes (Eukarya): not simple (compartments with special tasks)


■ Needed for life to appear because get energy plus oxygen was by product that helped rise of multicellular organisms

■ More oxygen also led to extinction of previous organisms

■ More multicellular cells led to more oxygen

○ The theory of how Eukaryotic cells came to be was that primitive cell took in other primitive cell but didn’t digest it instead the smaller cell exists in larger cell evolves into mitochondria (Endosymbiotic theory)

■ Mitochondria have own cell membrane, can make own protein and has own DNA

■ Mitochondria makes LOTS of energy which helps the cell grow much bigger than before

■ The same thing happened to plants plus they took in another primitive cell that makes own food (chloroplasts)

■ First the mitochondria was ingested since all Eukaryotic cells including plants have it, then ancestor of plants and protists ingested chloroplasts

○ Extinction of prokaryotes helped more Eukaryotes thrive (extinction because oxygen)

○ Protist: can be found at different parts of evolutionary tree (group with plant and animal)

■ Protist are the simplistic versions of animal, fungi and plants

■ NOT A GOOD GROUPING (debated)- put together because have mitochondria and more complex than prokaryote but simple

a. Not a natural group but catch all

■ Larger cells, more complex- build more sophisticated molecules ■ SEXUAL AND ASEXUAL reproduction

■ Complex energy production: zooplankton (consumer), phytoplankton (producer) and plasmodium (pathogens)

○ First multicellular organisms appeared 650 million years ago, 540-490- increase of fossils probably due to mass extinction (still haven’t left water) ○ To leave water need to make own food because no other organisms, first to leave were the green algae, then fungi because relationship with algae and finally amphibians (because food was available- first fossil of terrestrial animals are spiders and millipedes from 410 million years ago)

○ Plants:

■ Multicellular

■ Producer with some exception

■ Asexual and sexual reproduction

■ Provide us with oxygen, food and medicine

■ Prevent carbon dioxide build up and runoff

○ To leave water, plants changed:

■ Cuticle: waxy around cell and protect against water loss

■ Stomata: pores that open and close- absorbs carbon dioxide prevent water loss

■ Two organ system: shoot system (photosynthesis and root system (water and minerals)

○ Fungi:

■ Single-cell or multicellular

■ Have rigid cells, chitin made of glucose and protect cell because strong a. Allows thread of fungi to easily penetrate the ground

■ Consumers, are absorptive heterotrophs (put chemical on food and then absorb the released molecules)

■ More related to animal than plant

a. What hurts fungi will hurt us so hard to treat fungal infection

■ MOST IMPORTANT decomposer on land, recycling nutrients by breaking down leaf litter and dead organisms into inorganic chemicals which other organisms use as food

○ Animals:

■ NO CELL WALL- more flexible cells

a. All offers have cell wall

■ Ingestive consumer- can pull organisms in and put in special


■ Complex body plans:

a. Cells come together to make something big (tissue, organ, organ


b. Tissue: group of cell that do one function, organ: different levels of

tissue, organ system: organs coming together

■ Specialized areas:

a. Symmetry

b. Cephalization (brain and nervous system)

c. Development

○ Most animals exhibit either radial or bilateral symmetry:

■ Radial:

a. Equal division around central core

b. Greater access for sessile organisms to their environment

■ Bilateral:

a. It divides the body into two halves that mirror each other

b. Lead to cephalization (concentration of sensory structure at one


c. Made directional movement more effective

d. Enables rapid and efficient locomotion

○ Embryonic body plan

■ Development:

a. Egg + sperm = fertilization

b. Cell division = more cells

c. Cells become more specialized (form tissues, form organs, form

organ system)

■ First form gut for digestive system

a. Protostomes = mouth first

b. Deuterostomes = anus first

c. Need digestive tract when born to grow later

● Evolutionary thought

○ Evolution: descent modification by natural selection

■ In islands there is a lot of evolutionary pressure due to limited space and resources so Darwin and Wallace see as example

■ All life is link through a common ancestors

■ Populations CHANGE OVER TIME

■ Environment influence change

■ Advantages traits > less-advantageous traits

○ How does natural selection work?

■ Observation 1: fertility and exponential growth is limited

■ Observation 2: stable population with seasonal fluctuations

■ Observation 3: environmental resources are limited


■ Observation 4: no two individuals are exactly alike

■ Observation 5: different are heritable



○ DNA:

■ Gene: section of DNA that will contribute to physical/behavioral


■ Alleles: version of the gene that can exist

a. Can increase, decrease, appear or disappear

■ Gene pool: all alleles in a population (proportions/percentages of traits in population)

○ Population of one species will get different traits if they are separated for long period of time and in different environment

○ 4 mechanisms of evolution:

1. Mutations

2. Gene flow

3. Genetic drift

4. Natural selection- only one that helps population to be better adapted so NOT RANDOM

○ Mutation:

■ Any change in DNA of organism

■ ALL variation comes from mutations/genetic recombination (only way to change DNA over time)

■ Mutations can be harmful, beneficial or neutral

■ Ex: DTT sprayed on mosquito, some had mutation prior that made them resistant so reproduced and population became resistant

○ Gene flow:

■ Exchange of alleles between two different populations

■ New alleles are introduced or removed

■ For species to form, gene flow has to be stopped

○ Genetic drift:

■ Change events leading to difference between individuals in reproduction or survival within population

■ Not based on characteristics of individuals

■ Can be due to environment, reproductive and founder effect (few individuals establishing new population so diversity limited to only their alleles)

■ May lead to bottleneck (few individuals survive)

a. May decrease genetic variation

b. Fixation: only one version of characteristics

c. May increase extinction

○ Natural selection:

■ Individual with favorable traits have increased reproductive rate ○ 3 types:

1. Directional selection: one end of spectrum preferred

a. Ex: moth that were dark increased because trees had pollution on them, after clear air act the tree got light so the population of moth became light too

2. Stabilizing selection: middle of spectrum preferred

a. Ex: can be seen in birth weight in human babies because it is better for them to be in the middle rather than too small or big

3. Disruptive selection: both ends of spectrum preferred

a. Ex: RARE, birds have either small or big beaks because the food is either too big or small

○ Can affect behavior, development or structural adaptation

○ Sexual selection:

■ Can lead to sexual dimorphism (female and male don’t have same traits) ■ Due to females placing selective pressure on males

■ Human mate selection: men look for femininity, attractiveness or health; women look for masculinity (large jaws, prominent brows) and symmetry ○ EVOLUTION DOES NOT CRAFT PERFECT ORGANISMS

○ There are 6 lines of evidence for biological evolution:

1. Fossils (any imprint or remain of organism)

a. Some groups have lots of evidence as progression- ex is horse going from 4 toes to one

2. Traces of evolutionary history (fetuses look alike and similar structures in different organisms)

a. Different in embryo depend on genes that get turned on/off

homologous, characteristics shared by two groups of organisms because common ancestor

b. Vestigial organs: reduces or degenerate parts whose function is no longer needed by organism

c. Convergent (analogous) evolution: similar environment leads to

similar adaptations

3. DNA (can see where species diverged based on differences and


4. Direct observation (we do it through artificial selection- only individuals with certain traits are allowed to breed)

a. Selecting for our needs (domestic animals and farming crops)

5. Geographic distribution (can see distribution based on prior continent location- have moved through continental drift)

6. Macroevolution (rapid evolutionary change due to environment)

a. Harsh conditions can drive this

○ Main player of life:

■ Domain (3)- Bacteria, Archaea, Eukarya

■ Kingdom (6)- Bacteria, Archaea, Protista, plantae, Fungi, Animalia ○ Sex: exchange of genetic information

○ Prokaryote sex:

■ Conjugation: two cell connect and exchange DNA between living bacteria a. Using conjugation tube to connect

■ Transformation: DNA taken up from environment (used to belong to dead) a. Can result in pathogen strain and antibiotic resistance

■ Transduction: exchange of DNA through infection by phages (viruses) ● The Origin of Species

○ What are species?

■ MORPHOLOGICAL SPECIES CONCEPT is separate and distinct group of organisms by unique set of physical traits

■ BIOLOGICAL SPECIES CONCEPT is group of populations that can interbreed with one another but are reproductively isolated from other groups

a. Limitations: male and female of species might look different, some species look similar but can’t mate, and asexual reproduction

species can’t be seen as species because they don’t mate with


■ GENETIC SPECIES CONCEPT is group of organisms that may inherit traits from one another (sex), have common gene pool (similar DNA) and is reproductive community that forms genetic unit

a. One used in class

○ Systematics: study of the evolution of groups of organisms

■ Look at:

a. Developmental traits

b. Physical traits

c. Genetic traits

d. Behavioral traits

■ Trying to make evolutionary tree that show lineages, groups splitting off and development of new traits

○ Construction of trees:

■ TIPS- taxon/taxa (group being studied)

a. Also known as species

■ BRANCHING POINTS- node (point of divergence between groups) a. Shows independence from common ancestor

■ LINES- lineage (descendants of common ancestor) CHANGES OVER TIME

a. Continued evolution until next branching point

○ What goes into trees?

■ Characters: heritable traits that can be compared across organisms (shared derived features)

a. SHARED because it can be seen in at least two lineages

b. DERIVED because it is a new character for those above tree ○ TREE NOT LADDER (all equal no one better than other)

■ Only showing how they relate

■ No main line or sidetrack

■ No organism is “more evolved” than other

○ Trees can help you guess traits that extinct animals had- ex: dinosaur having parental care

○ Speciation: process which one species splits to make two or more species that are reproductively isolated (NO GENE FLOW)

■ Reproductive isolation prevents gene flow: pre-zygotic barriers (before sperm and egg unite) and post-zygotic barriers (after sperm and egg unite)

○ Pre-zygotic barrier:

■ Temporal isolation: mate, eat or are active at different times

a. Won’t be reproductively active at same time

■ Ecological isolation: have different habitat so won’t interact

■ Behavioral isolation: not doing right behavior to mate

a. Seen in birds- have to do right dance or pattern to mate naturally ■ Mechanical isolation: physically can’t mate because don’t fit/work ■ Gametic isolation: to fuse sperm needs things outside that let in enter egg so here sperm doesn’t have right things

○ Post-zygotic barrier:

■ MOST ZYGOTE DIE (DNA not compatible so won’t divide)

■ Hybrid performance (hybrid is infertile or hybrid breakdown with their kids or grandkids not being fertile)

○ When does speciation occur?

■ Geographic isolation (allopatric speciation)

a. EASIEST path to reproductive isolation/preventing gene flow b. Distance required VARIES FROM SPECIES TO SPECIES

c. Rising species: develop when population loop around geographic barrier and at two ends of loop are in contact with one another

d. One population physically separates by geographic barrier so

can’t reproduce- separated for long time so new behavior or

factors rise that stop reproduction

■ Non geographic isolation (sympatric speciation)

a. Plants-genetic tricks- rapidly change in chromosome numbers = polyploidy

b. Hybrid are made

c. Can occur in animals- lake Victoria cichlids- one population

became different through specialized diets and sexual selection

until different population- and apple maggot flies- those that feed

on apples tree don’t mate with those feeding from hawthorns

i. Pollution now hurting number of species because fish can

no longer tell who is right color to mate (500 species to

about 300)


■ Speciation occur when gene flow stops and reproductive isolation occurs EVOLUTION HAS NO END GOAL

■ Gradualism: small changes accumulate over LONG period of time resulting of fast changes

■ Punctuated equilibrium: long period of no change interrupted by periods of fast changes

■ Adaptative radiation: when a group of organisms expands to take a new ecological roles and to form new species

a. During extinction event that allows one group to quickly evolve to life organisms

b. This happens because of decrease in competition and new

adaptations that enables it to use environment in new way

■ Islands rates are different- ISLANDS ARE CENTERS FOR SPECIATION AND EXTINCTION (have geographical isolation and ecological isolation) a. Island biodiversity is vulnerable because effects of genetic drift and invasive species

○ ON TREE- line = microevolution, node of divergence = macroevolution


■ Mutation, gene flow and genetic drift are random

■ Natural selection is only way that species become more adapted


■ Last two is postzygotic (after hybrid) and other 5 are pre-zygotic (way to make new species)

○ Problem with evolution is that adaptations serve as match-maker between population and environment (leads to complex characteristics and important functions but bad if environment changes too fast)

○ Adaptations has allowed multidrug resistant pathogens because of overusing antibiotics, not taking entire prescription, agricultural/industrial use or overuse of substance

■ Agricultural use of antibiotic leads to runoff and it being everywhere, not taking enough allows some to live on and become resistant

○ Coevolution: interaction between two species strongly influences their survival so they evolve in tandem

■ Problem if one species dies off because other is dependent and may die too

● Ecology:

○ Can look at ecology through different biological hierarchy (biotic factors) ■ Organism, population, community, ecosystem, biome and biosphere ○ Can look at abiotic factors: conditions of environment

○ Population: individuals of species in an area

■ Hard to count because of migration organisms, flying organisms and microscopic or small species, hard to reach habitats, rare organisms and organisms with different forms through lifetime

○ Ecology: study of abiotic and biotic factors within a defined area

○ Human population is growing exponentially

○ Patterns in population growth:

■ J shape (exponential growth)- constant rate (population in year x constant rate)

a. N (next year) = λ (constant rate) x N (this year) 

■ S shape (logistic growth)- population grow with limit (limited by carrying capacity)

a. Carrying capacity = max number of individuals in enviroment,

number may change over time with change in climate/environment

■ Irregular fluctuations (limiting factors have huge impact)

a. Combination of exponential and logistic

b. Population cycles: demonstrated by predator-prey relationship

○ Growth-limiting factors:

■ Density- independent (related to genetic drift- random)

a. NOT RELATED TO SIZE OF POPULATION (weather, fire and foods and pesticide)

■ Density-dependent:

a. RELATED TO SIZE OF POPULATION (food shortages, lack of habitats, disease, predators)

○ Communitie: looking at all interaction of all individuals in community ■ Biodiversity:

a. Species diversity: species richness (has a lot) or relative

abundance (not many)

b. Geographic diversity: distribution of community across of

geographical range

c. Genetic diversity: variation of genes within populations

i. Good when looking at stability of community


i. Especially if you have diversity in producer

○ Symbiosis: interaction of two or more species through their lifetimes ■ Often mistaken as always being beneficial when they can be positive, negative or neither

○ Mutualism: type of symbiosis where BOTH species benefit from interaction (+/+) ■ Benefit is that organisms will survive and reproduce

■ Ex: gut inhabitant in humans that help digest, help immune system to see bad pathogens in food, influence mood and make nutrients (also seen in termites- can digest cellulose because of microbes)

■ Behavioral mutualism: behavior of two organisms will complement one another

a. Ex: goby fish looking out for blind shrimp and shrimp providing shelter to goby in burrow

■ Problem because can become so dependent on each other that if one goes extinct so will other and can have an affect on geographic

distribution of others (indirect effect)

a. Ex: yucca plant and moth

b. Ex: coral reef and algeae affecting where fish live

○ Commensalism: one organism is benefiting from interactions while other has no positive or negative consequences (+/0)

○ Exploitation: one organism benefits while other is harmed (+/-) ■ Fall into three categories:

1. Herbivore: eat plants or plant parts

2. Predators: kill other animals for food

3. Parasites: live in or on organisms they eat

■ Induce defenses: plants can develop ways to protect themselves from consumers (grazed island cacti have more spines than those in ungrazed islands)

■ Warning coloration: vibrant colors in organism to say “I’m toxic, don’t eat me”- frogs with vibrant colors are toxic

■ Camouflage: blending to background to hide from predator

■ Mimicry: looking or looking like other species

a. Batesian mimicry: one species copies from other to gain protective capacity (one species is NOT dangerous)

i. More beneficial for predator

b. Mullerian mimicry: several species looking alike and harming predator (both harmful)

i. More beneficial for prey

c. Behavioral adaptations: individuals help each other out in

population (alter behavior and act together to survive)

■ Parasitic relationships:

a. Parasites: live on or in a host from which it gets nourishment i. Internal parasite include nematodes and tapeworms;

external parasite include mosquitos and ticks

ii. Some parasites might lead to behavior in host organisms

that benefit parasites (mouse with parasites will go out in

open and get killed by cat)

b. Pathogens are DISEASE-CAUSING parasites (can be bacteria, viruses, fungi and protist)

■ Introduced species sometimes disrupts ecological communities (due to less parasites than home, lack of predation or distribution/abundance) ■ Consumers can restrict distribution of prey (American chestnut trees live in isolated patches because of parasitic fungus)

○ Competition: both species are harmed by interaction (-/-)

■ Occurs when two species depend on same resource to survive a. Have the same niche: role of a species in an ecosystem

■ One species benefits from other extinct because no longer in competition ■ 2 types:

1. Interference competition: direct exclusion, competition between two species affects distributions of those species

a. Ex: chthamalus being excluded from better lower part of

shore because of semibalanus growing there so stuck on

higher half

2. Exploitative competition: both depend on same FOOD (share prey or resource to survive), use by both reduces amount available to one another

■ Can lead to:

a. Limit distribution and abundance of species that share resources or space

b. Localized extinction: caused by competitive exclusion, all die c. Coexistence: share habitat

d. Niche partitioning: adapt to use niche in different way so decrease competition

e. Can increase differences between species- CHARACTER


i. Species evolve to become different over time

○ These interactions can lead to coevolution: interdependence evolution of two or more species (ex: flowering plants and pollinators)

■ Problem is that if one goes extinct then others might too

○ Food web: will highlight all interactions within trophic composition ■ Contain MANY FOOD CHAINS- bottom are producers then go to other consumer (primary, secondary, tertiary)

a. Arrow shows energy being given, pointing to what eats it

■ BASE of trophic recycling is DECOMPOSER

a. Recycle nutrients to be used again

○ Only 2% of sun energy is assimilated in photosynthesis

■ Gross primary production: TOTAL material produced through photosynthesis

■ Every time consumer eats other they only get 10%, rest goes into survival ■ Net primary production: amount of material plant accumulates ○ Producer → primary producer → secondary consumer → tertiary consumer → quaternary producer

■ Too much energy required to support quaternary consumer

■ Top predators rely on producer and stability of others

a. If decrease producers then all consumer will decrease because all community depends on base

b. Any problem or change in consumer population (top predator) is due to change in bottom population

○ Keystone species: have HIGHEST impact on community, if removed, entire community can change

■ Doesn’t have to be biggest population

■ May or may not be predator (ex: fig trees, elephants and humans) ■ Ex from California to see if keystone- took out starfish from site and found one species had huge effect (sea star is pisaster)

○ Building/replacing communities:

■ Succession: communities changing over time- stirring for a mature community

a. Succession stops, this only lasts for some time then it starts to change again

■ Primary succession: colonizing a new habitat (volcanic islands and glacier retreat)

a. Usually at first only have bacteria and fungi, overtime get seeds

with plants and later animals


■ If you have a disturbance or catastrophe, secondary succession will occur can be good (natural fire) which leads to new growth

■ As climate changes, so will communities (as shift of climate occurs then you see change of community)

■ Human can cause disturbances- clear-cutting or pollution, can recover but need to change practices to stop hurting action

a. Problem of overgrazing of grasslands which leads to it becoming a desert (can’t be restored- Trinity site of atomic bomb destroyed

grassland and hasn’t recovered)

○ Need to understand community because need to survive (can lead to ethical implications, decrease of aesthetic, decrease of economy and impact on health) ● Climate

○ Temperature is related to the sun radiating heat, visible light and UV light on us (electromagnetic radiation)- Ozone is trapping heat in and filter out damaging radiation

○ As you admit certain types of chemicals into atmosphere will help retain heat and increase temperature

■ More carbon dioxide, methane, nitrogen oxide and water vapor increase temperature

○ Temperature changes based on location:

■ As you move up, decrease temperature (elevation increase= temperature decrease)

■ Increase light exposure = increase temperature

a. Tilt causes Equator to have constant light so has consistent warm temperature (not true for other sections)

b. Seasons are due to tilt of Earth because one half is pointed toward the sun white the other is not

○ As you heat sometime up, you add heat energy (molecule movement) and based on amount of movement it will turn to gas, liquid or solid

■ In area with constant heat, air will be warmer and move up atmosphere, become cold and move down again

a. Air moves in 2 circles from Equator (up in Equator toward pole,

down other way)

■ Warm air holds more water- when it gets cold as it moves up, water will come down as precipitation (will also get moisture

as moving down to temperate zone)

a. Reason why it rains more in tropics

○ Giant convection cell:

■ 4 stable and 2 variable- 2 polar, 2 tropical and 2 in between (due to rotation)

■ In stable, winds go East, in variable they go West, hurricanes will move wind East in variable but will usually be pushed due to West wind ○ Water cycle: when water heats up it becomes gas and moves up atmosphere (evaporation and transpiration) due to increased temperature and winds, when water cools down it becomes liquid and falls back to the surface (precipitation) can be due to cold atmosphere and land squeezing water out (in mountain, windward side promotes raise while leeward side have no moisture- desert)

○ Water absorbs lots of heat from sun and releases heat slowly during night (causes moderate temperature in surrounding land)

○ Oceans: changes in ocean current will affect climate

■ Currents are influenced by Earth rotation, difference in water temperature, prevailing winds and gravitational pull of sun and moon

■ Gulf stream moves warm water toward Europe which is why it is less cold there than in places of same altitude in North America

○ Productivity: solar energy - chemical energy

■ Limited by nutrient availability

■ Transfer of nutrients between organisms and the physical environment a. Food chain/web

b. Reservoirs

c. Exchange pools

■ Two kinds of nutrient cycles

1. Atmospheric

2. Sedimentary

○ Primary productivity: biomass and limiting factors

■ Sunlight, temperature, moisture and nutrients

■ Nutrients can be recycled

■ Energy flow: sun → producers → consumers → decomposers ■ Main rate limiting factor in terrestrial is sunlight; in aquatic is nutrients ○ Secondary productivity: consumer biomass (helps look at biodiversity) ○ Reservoirs: limited to almost no access by organisms

○ Exchange pool: readily available to organisms


Type of cycle

Most important

aspect of the


How humans

impact it






Use up reservoir burning fossil fuels




Use up reservoir nitrogen fixation



Water (NO


Puts lots of it into the atmosphere



Mostly salt water

Pollution/melting the ice caps



Stored in rock

Use up reservoir extracted from rock

○ Terrestrial Biomes:

■ Even distribution of the way they are organized around the globe (equator to poles- rain forest on Equator to tundra in poles)

■ How TERRESTRIAL BIOMES are distributed and what organisms you have depend on moisture and temperature

○ Aquatic biomes:

■ Will be influenced by the terrestrial biomes near them

a. Land topography

b. Nutrients in the terrestrial biomes

■ Climate:

a. Temperature, rainfall, wind

b. Seasonal changes and major events (El Niño)

■ Physical characteristics:

a. Salt concentration, depth, movement

○ Human effect:

■ Increasing the amount of carbon in atmosphere:

a. Only limited amount of CO2 in atmosphere so there is a huge

impact when the number changes increases (more heat trapped)

b. Humans burn fossil fuels (75%)

c. Humans reduce plans that decrease CO2 by taking it in (25%)

d. Affecting the evolution of plants because they are starting to

increase photosynthesis and water use, few species can maintain

growth (will end up dropping the growth of some which will lead to

a loss of biodiversity)

■ Industrial nitrogen fixation:

a. Remove nitrogen from atmosphere to make fertilization b. Combustion from factories also add nitrogen to atmosphere c. Run off is the real problem (eutrophication)- goes into aquatic

system which allows certain algae to grow and won’t let sunlight in so the producers can’t exist and bacteria grows too much (WON’T BE ABLE TO SUSTAIN LIFE ON IT- DEAD ZONES)

d. Occurs in Chesapeake Bay and where the Mississippi meets that Gulf of Mexico

■ Sulfur dioxide released during burning of fossil fuels

a. Has international impact

b. Leads to the increase of acid rain and reduces plant life c. The sulfur made in USA are carried to Europe - have seen improvement due to Clear Air Act

■ Getting fresh water by diverting rivers for agricultural use in areas with little precipitation

a. Huge decrease in river inflow, less net evaporation (no more water), and overall less amount of water available in lakes b. Change climate in areas- no longer have precipitation and desert-like temperature because there is no more water

■ Bioaccumulation: chemicals we make synthetically

a. Persistent organic pollutants (POP)

i. Long-lived (can’t be broken down by most organisms) ii. Harmful effects

iii. Ex: polychlorinated biphenyls (PCBs) and dioxins almost killed Ukrainian politician Viktor Yushchenko which hurt

him a lot

iv. Problem is that they are used near organisms that we eat and since those organisms can’t digest the toxin so we

might end up taking the toxin in when we eat them

b. Pollution movement:

i. Pesticides- DTT: detrimental to bird populations

ii. Chlorofluorocarbons (CFCs): damage to ozone

iii. Endocrine disrupters: bisphenol A (BPA) and Phthalates c. Can lead to an increase at successively higher trophic levels and resistant to degradation in the body (amount of chemical increase as you go up the levels because they won’t get digested by the organisms so the top predator takes in a huge amount of it) ■ Introduced species to different environments that become invasive a. Become invasive because don’t have predators or parasites so their population size is not controlled

b. The estimated damage from invasive species worldwide total more than $1.4 trillion

c. Ex: zebra mussels from Asia through cargo shipments when they take in water from their origin and release the water ballast in destination (bring in organisms as well)

■ Ex of web of interconnected relationships: Australia

a. Wanted to get rid of dingoes that were eating the sheep b. Problem is that when you remove dingoes the kangaroo grew a lot and started eating the same plants are the sheep so now there was no food for the sheep

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