AP Biology Notes

Unit 1: Chemistry of Life

Unit 2: Cell Structure and Function

Unit 3: Cellular Energetics

Unit 4: Cell Communication and Cell Cycle

Unit 5: Heredity

Unit 6: Gene Expression and Regulation

Unit 7: Natural Selection

Unit 8: Ecology

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Unit 8: Ecology

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SYSTEMATICS/PHYLOGENY

Systematics: classify organisms and determine evolutionary relationships

Phylogeny: Evolutionary history of a species and related species

Determined through fossils and homologous structures

Phylogenetic Tree: visualizes inheritance and relationship between species (divergent evolution)

Dating Fossils:

Relative Dating: look at fossils and determine age relative to anothertells the order in which different species exist → not exact date

Index Fossils: organisms that we know when existed, refer to this for a new fossil (e.g. trilobyte) to determine when it existed

Lower the rock strata, older the fossil is in it

Absolute Dating: radiometric dating, use radioactive isotopes (carbon dating=C14), C14 decays over time at a specific rate, less C14 = older

Taxonomy: classification of organisms

Carl Linnaeus: creates binomial nomenclature, two word naming system (genus species)

Homo sapies, Canis lupus, etc.

Taxonomic Categories: (taxons)

Species Genus Family Order Class Phylum Kingdom Domain, each taxon more comprehensive than the previous one

Cladistic Analysis: used to make phylogenetic tree

Cladogram: look at number of structures shared in common (homologous), more in common → closely related

Cladogram doesn’t give TIME like phylogenetic tree

1. Tells order when characters evolved and 2. order in which species evolved

Shared Primitive Character: a trait that is preexisting (you inherit from common ancestor)

Shared Derived Character: new trait you get that makes you unique from other descendants

Outgroup (O) comparison: species that existed before any members of the ingroup, less closely related but still a starting point, not real member of the cladogram Only has that one starting character in the cladogram

First character will be the one that is shared by all organisms

Look for:

Synapomorphies: characters shared by groups (homologies)

Parsimony: simplest explanation is usually the correct one (Occam’s Razor)

Construct tree on the basis of simplest shared (inherited traits) and simplest derived (new similar traits different from preexisting) characters

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Cladogram shows the inheritance of specific characters, whereas a phylogenetic tree has taxa (branches) that show time

Monophyletic Taxon: have ancestor and all species that evolved from it (complete evolutionary history branch, best option

Polyphyletic Taxon: are closely related by don’t yet know the common ancestor (humans)

Paraphyletic Taxon: incomplete branch has common ancestor but some descendents aren’t known

Which taxon you have depends on many fossils you discover

ECOLOGY

Ecology: the study of how organisms interact with their environment (intertwined with evolution, environment creates selection pressures, ecology studies the results between environment and organisms)

Biotic Interactions: between living organisms predator-prey relationships, symbiotic relationships,

Abiotic Interactions (Abiotic factors CONTROL biotic factors): between nonliving things and living organisms, things like weather, climate, water, geography, etc., control where the living organisms can actually survive

Levels of study:

Organismal Ecology: interactions that happen within an organism

Population Ecology: group of organisms of the same species living in the same place at the same time, study interactions within a population

Size (total number of individuals is always shown by the letter N)

Density (total number of individuals per square unit area)

Clumped: found in specific regions

Uniform: spread out with an even rate

Random: spread out randomly

Community Ecology: study groups of populations in the same area together and study the interactions of different species populations (predator prey relationships)

Ecosystem Ecology: biological community + abiotic factors in an ecosystem, study interactions therein

Landscape Ecology (biomes): major ecosystems of the planet

Global Ecology: interactions on the planetary scale

Demography: study of vital statistics in a population over time

Life Table: age-specific summary of a survival pattern of a specific population

Survivorship Curves: different populations follow different curves

Type I: (humans) most individuals die old

Type II: (squirrel roadkill) length of survivorship is random

Type III: most individuals die young (most animals and bacteria)

Life-history Strategies: lifestyle affected by survivorship curve

K selected (type I, K for care):

Produce less offspring, because they live old

Invest more parental care → live long life

Pros: you’ll probably live a long life

Cons: population size is slow to recuperate if the population is decreased, elephants are k selected so when poached, population will recover too slowly

R selected (type III, R for risky):

Produce many young: very little parental care

Short life expectancy

Pros: can recover very fast from population decrease

Cons: risky lives

Mice, insects, bacteria

Size increases as gestation time increases

Population Growth: how fast is a population growing?

Biotic Potential: max growth rate of population under ideal conditions

Factors:

Age of reproductive maturity

Clutch size: how many babies to have at one

Frequency of Reproduction (gestation period)

Reproductive lifetime (how long are they reproductively active?)

Survivorship of offspring

Carrying Capacity (shown by the letter K): max amount of individuals in a population

Limiting Factors: limit population growth

Density-dependent limiting factors (more important): increase as the population size increases, have more and more of an effect on the population, more competition and predation takes place, more disease/parasites, more stress, etc. stops population from going past the carrying capacity

Density-independent limiting factors: isn’t changed as population increases, just decreases numbers in total → e.g. natural disasters

Mass death would occur if you reach and pass the carrying capacity

Calculating population growth rate (SLOPE OF THE LINE), change in y/change in x= (y2-y1)/(x2-x1), time is x and change is y

N/t pop size over time = B - D (briths - deaths)

ZPG (zero population growth): when a population hits carrying capacity when slope is 0 so when N = K then rate = 0

If slope is positive then population is growing, if negative then it is decreasing

Logistic Population Growth (S shaped curve): pop size increases and levels off by the carrying capacity, the rate turns to 0, and stays around carrying capacity for NORMAL populations

Exponential Population Growth (bad): occurs when a limiting factor is removed (predators become extinct, competition is eliminated, etc.) J shaped curve, WILL EXCEED carrying capacity → mass death (run out of resources, or disease happens) without predators, they are going to overproduce

Why humans are growing exponentially:

Increase in food supply

Reduction of disease

Expansion of habitat

Reduction in human waste (septic system)

Community Ecology: study of multiple populations put together

Competition: takes place due to limited resources

Intraspecific Competition: competition WITHIN a population (for mates)

Interspecific Competition: competition BETWEEN populations (all competing for the same sources of food)

Niche: your job and role in community (if you obtain food, shelter, etc.)

Fundamental Niche: optimal niche without any other competition (if population existed in isolation), where/what you would like to do

Realized Niche: what the populations actually end up doing because of competition

Interference Competition: physically fighting each other for the right to mate in a population

Exploitative Competition: better getting resource than other individuals, they remove the competition’s resource

Competitive Exclusion Principle: two species cannot occupy the same niche at the same time, one species would be outcompeted to extinction (no one can have the exact same source of water, shelter, food, etc.)

Resource Partitioning: instead of competing until one species dies for a niche, the populations split up their resources, one population will begin doing something different to get some resources while the other takes the niche (peaceful coexistence)

Character Displacement: traits of a population change in order to adapt to a new niche from resource partitioning because of a niche shift

Predation: eating of live or freshly killed organisms

Parasite: only type of predators that don’t kill prey/host, just feed off them

Predator-prey populations keep each other in check, the prey is not controlled without the predator and the predator cannot exist without the prey (prey goes up, predator goes up, prey then goes down, predator goes down → fluctuating/cyclic pattern)

Lag time: time it takes between populations for each to affect each other, measure distance between peaks/valleys in the wave

Defenses: example of coevolution, evolution of one species due to another

Cryptic Coloration (camouflage): camo

Aposematic Coloration: bright colors indicate poison

Mimicry: look like another organism as a defense mechanism

Batesian Mimicry: a harmless species mimics a harmful species to scare away predators

Mullerian Mimicry: when two bad species mimic each other(all bees look the same so all animals know to stay away from bees)

Symbiosis: close and permanent relationships between organisms of two species, two species that are totally dependent on each other

Mutualism: when both organisms benefit from the relationship

E.g. clownfish and sea anemone, live together permanently, clownfish cleans the sea anemone, and clownfish gets protection

E.g. Remora cleans the inside of the mouth of a moray eel/shark, but also eats up all the parasites and bad stuff in the eel’s/shark’s mouth

***Lichen: TWO different species that live together it’s a fungus + algae, algae make food using photosynthesis, but fungus lets algae attach to trees and rocks to live on land, so fungus gets food in return.

*** Mycorrhizae: plant root and mycorrhiza, the plant takes in more water and nutrients because of the fungus because it increases surface area, the fungus also gets food from plant (oldest mutualistic relationship, since plants first evolved from algae)

Commensalism: least common type of symbiosis, one species benefits and nothing happens to the other (neutral)

E.g. egrets live on top of rhinos, elephants, get protection, but the rhino/elephant gets nothing in return

E.g. Plants that grow on the branches of large trees, gets more sunlight, and the large tree gains nothing

Parasitism: one species benefits and the other is harmed (ticks)

E.g. Cuckoo/Brown headed Cowbird, parasitic bird that flies around and kills the babies in a found nest, then lays its own eggs for the returning mom to feed them and raise the cowbird’s young

Community Composition and Stability: no biological community remains the same for a period of time, always changing, constant state of change

Ecological Succession: the natural change in the composition of species over time, this is initiated through some type of disturbance (a storm, drought, humans, overgrazing, etc.)

Primary Succession: begins when a community is totally wiped out, starting from nothing but bare rock (catastrophes, forest fires, clear cutting, construction, volcanoes, etc.)

Pioneer Species: (usually lichen, bacteria, moss, protists, etc.) first species to move into the area ***break down rock and turn it into soil (broken down rock + decaying organic material)

Small R-selected plants (weeds/annuals) move in with short life of one year

K-selected plants move in (perennials, comes back year after year) shrubs, bushes, etc.

R-selected trees move in, pine, poplar trees

K-selected trees maples, birches, oaks, etc., live for long times

Climax Community: mature, unchanging community → reduces biodiversity, more different stages of succession == more different types of species

Secondary Succession: starting from a middle stage (crop land that got abandoned for ex.)

Species Diversity:

Species Richness: number of different species that you have (but you can have a lot of different species but with one dominant one)

Relative Abundance: how many of each species do you have

Human Activities and Biodiversity:

Threats:

Habitat Destruction:

Deforestation: high extinction rate of plants and animals, forests are clear-cut, tree roots maintain the structural integrity of the land so if you cut down the trees, it can cause erosion, flooding, etc.

Introducing species:invasive species can be introduced into new areas where they don’t belong (boats, airplanes, cars, etc.), invasive species lack predators, competition, LACK density-dependent limiting factors and outcompete native species to extinction → grow exponentially

Overharvesting/Overhunting/Overfishing/Poaching: can hunt species to extinction, or damage/imbalance ecosystems

Toxins in the Environment: humans release damaging toxins in the environment

Biomagnification: tuna consumed human mercury wastes (carcinogen) through the food chain, phytoplankton eat the mercury, zooplankton each phytoplankton, fish eat the zooplankton, tuna eat the fish → mercury content isn’t lost organism to organism, but with less population, there is higher mercury concentration

E.g. PCB released into the Great Lakes ppm just keeps going up as you go up the food chain (herrings get lots of birth defects), DDT was so biomagnified that every organism has the carcinogen

Climate Change/Greenhouse Effect: when solar radiation hits the earth, some is absorbed and warms up the planet, some is reflected back into outer space.

Greenhouse Gases: (CO2 and CH4/Methane) They cause the greenhouse effect, work as a blanket over the atmosphere. Take the solar radiation that should be reflected and trap it in our atmosphere, cannot return to space → heat up planet

More CO2 and CH4 in our atmosphere than ever before

But CAUSES (increased global population, deforestation, burning fossil fuels, livestock (methane cow farts), natural causes), and effects of climate change are unknown → debate

EFFECTS: global warming also causes other things

Shifting weather patterns: air currents moving south, more severe storms, etc.

Increased glacial/arctic melting

Ocean acidification: CO2 + H2O → Carbonic acid

Changes in biological communities

Increased water levels

Increased ocean temperatures

Not all effects are known

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