AP Bio Unit 8 - Ecology

First Law of Thermodynamics

Energy cannot be created or destroyed

What is the energy flow for Earth?

sun → photosynthetic organisms (turn into chemical energy) → consumers use that chemical energy → energy is released through heat

Second Law of Thermodynamics (Energy Loss in a System) - How do we prevent entropy (disorder)?

The total entropy (disorder) of a system always increases over time because energy is lost through heat when it gets transformed. To keep things organized, we need energy.

Endothermic

organisms that regulate their body temperature internally (eg. metabolism)

What are endothermic organisms’ oxygen consumption at low temperatures?

Higher; they need to undergo more cellular respiration in order to maintain body temperature

Ectothermic

organisms that regulate their body temperature through actions and behavior (eg. cold blooded animals basking in the sun) - their body temperature is proportional to their environment

Autotroph

organisms that capture energy physically or chemically (photosynthetic and chemosynthetic)

Photosynthetic

uses sunlight to create usable energy

Chemosynthetic

use small inorganic molecules in their environment to create energy (sometimes in the absence of oxygen)

Heterotrophs

organisms that consume other organisms to gain energy (carbohydrates, lipids, proteins, NOT nucleic acids)

What method to heterotrophs use to get energy from the organisms they consume?

hydrolysis

What is the standard trophic structure for an ecosystem?

producers → primary consumers → secondary consumers → tertiary consumers → quaternary consumers (note: decomposers eat all of them when they die)

What percent of energy to consumers get from the organisms they eat?

10%

What happens if there is a change in the energy resource?

it affects the number and size of each trophic level

What happens if there is a change in the producer level?

it affects the number and size of each trophic level

Why do animals need to communicate?

• Finding food

• Finding a mate

• Alerting others of danger

• Establishing dominance

• Reproductive success

What is the main “point” in survival for all organisms?

reproductive success (for the individual and/or population)

Visual Communication

• A firefly glowing to attract a mate

• A peacock using their tails to attract a mate

• Cobras inflating their neck to scare off other creatures

Auditory Communication

• Elephants using their trunks to talk to other herds from a distance

• Whales using song to communicate with females

• Wolves howling to call wolves from their pack

Electrical Communication

• anytime an animal gives off an electrical signal to communicate

Tactile Communication

• Dogs licking their pups to bond

• Horses kicking other horses to establish dominance

Chemical Communication

• Cats marking their territory by rubbing their scent on things

• Ants using a pheromone trail to follow one another

Altruistic Behavior

When an organism sacrifices their own “fitness” to increase the “fitness” of their population/group

(eg. an animal alerting their group of a predator through making a call, but making themselves vulnerable by making noise)

Intersexual Selection

when individuals of a certain sex have the job of choosing which member of the opposite sex they want to mate with (often results in behaviors to attract a mate)

Intrasexual Selection

when two organisms of the same sex fight each other over a mate

Exponential Growth - Population

• unlimited growth of a population; unlimited resources

• rmax(N) = (dN/db)

• rate of increase = birth rate - death rate

• practice the formulas

What does the graph of an exponential growth population look like?

• J-shaped curve

• Exponential graph

Logistic Growth - Population

• a population with some sort of limited resource/limiting factor

• includes carrying capacity

• rN (K-N / K) = dN/dt

• practice the formulas

What does the graph of a logistic growth population look like?

• S-shaped curve

• Exponential but flattens out at carrying capacity

Carrying Capacity (K)

the maximum population size that can be maintained with the limiting factors and limited resources

Density Dependent Factors

Factors that are more harmful for larger populations

• competition

• predation

• disease

Density Independent Factors

Factors that effects small and large populations equally

• natural disasters

• human activity

Simpson’s Index

1 - Σ (n/N)

• a measure of biodiversity within an ecosystem

• measures 0→1

• the closer to one, the more biodiverse

• practice formula

Species Richness

having a large number of species in an ecosystem

Species Evenness

all of the species within an ecosystem having a similar population size

Predator/Prey

• positive/negative

• benefits predator/hurts prey

Herbivory

• animals eating plants

• positive/negative

• benefits herbivore/hurts plants

Competition

• negative/negative

• both are in competition and have less resources

Prefix “Endo”

• IN

• Inside

Prefix “Ecto”

• OUT

• Outside

Parasitism

• positive/negative

Mutualism

• positive/positive

Obligate Mutualism

• the two species need their interaction for survival

• eg. termite and the protozoan in it’s intestines

Commensalism

• positive/no effect

• usually never actually exists

Keystone Species

• would have disproportionate impact on their environment if removed

• their impact is not proportional to their abundance in their environment

(eg. sea otters - consume sea urchins, which prevents the kelp from being overgrazed)

Invasive Species

• not native to an area

• no natural predators, so they go through exponential growth

Chi Square

• used to determine statistical significance

• whether or not to accept or reject null hypothesis

• critical value → found in degrees of freedom table

• degrees of freedom = n - 1

• practice formula

Null Hypothesis

the hypothesis for which the independent variable has NO EFFECT on the dependent variable (H0)

What is behavior?

response to stimulus

How does natural selection of behaviors work?

animals with better innate and learned behaviors will have better survival and reproductive success

Population

a group of the same species living in the same area

Community

all of the populations that live in an area and interact with each other

Ecosystem

the organisms and abiotic factors in an area

Biome

a large geographic area with similar climate and vegetation

Nutrient Cycling

nutrients (carbon, nitrogen, phosphorus) cycle through the environment and its organisms and return back to the environment

What are the primary biogeochemical cycles?

• water cycle

• carbon cycle

• nitrogen cycle

• phosphorus cycle

Water Cycle

• precipitation (rain)

• condensation (clouds)

• transpiration (plants absorbing water)

• evaporation (water to air)

• surface runoff

• subsurface flow

Carbon Cycle

• photosynthesis (takes in CO2)

• cellular respiration (exhaling CO2)

• decomposition (releases CO2)

• combustion (burning of things releasing CO2)

Nitrogen Cycle

• nitrogen fixation (bacteria take it from the atmosphere for plants)

• nitrification (turns waste and matter into nitrogen for plants)

• denitrification (nitrogen goes back into atmosphere)

Phosphorus Cycle

• weathering (phosphorus in rocks breaks off into water)

• absorption (plants absorb phosphorus in water)

• incorporation (animals eat plants with phosphorus)

• decomposition (phosphorus goes from dead matter back into rocks)

Species Diversity

• different numbers and populations of species

• (eg. one shark species (65 sharks) and one turtle species (500 turtles)

Species Composition

• identity of each species

• (eg. this ecosystem has Pomacanthus paru and Pomacanthus xanthometopon)

Trophic Cascade

the negative effect of removing one key species on the other trophic levels around it

Niche Partitioning

a decrease in competition because species are gaining more differences in their niches (eg. two organisms who use the same resource reduce competition by accessing the resource in different ways)

Adaptations

• occur through mutations

• a species will favor those who have a mutation that makes it easier to survive

How can geological and meteorological activities affect ecosystems?

• accelerate evolution

• cause extinction

• create new niches

Innate Behavior

• behaviors you are born with

• (eg. circadian rhythm, baby sucking milk)

Habituation

when an organism stops responding to a stimuli

Types of Learned Behavior

• Classical Conditioning (associating one behavior with another; dog associating a bell with a treat)

• Operate Conditioning (positive or negative reinforcement)

• Observational Learning (watching someone else do it)

Kinesis

change in speed in response to a stimulus

Taxis

a reflex or movement toward or away from a stimulus

Types of Plant Behavior/Tropisms

• Gravitropism - response to gravity (root growing downward)

• Phototropism - response to light (leaves growing upward)

• Thigmotropism - response to touch (sleeping grass)

• Hydrotropism - response to water (roots growing towards water source)

Types of Defense Adaptations

• Mechanical (physical defense)

• Chemical (releasing a poison)

• Coloration/Appearance (looking scary as a defense)

Aposematic Coloration

• poisonous animals using bright colors as a warning

• also known as warning coloration

• (eg. poison dart frogs and monarch butterflies)

Batesian Mimicry

an organism resembles another poisonous or harmful organism to fend off predators

Mullerian Mimicry

when two poisonous organisms look similar in order warn predators that they are both harmful

Survivorship Curves

• Type I - many organisms live to be old, then die quickly (humans)

• Type II - mortality rate is same at all ages (small mammals an birds)

• Type III - high mortality rate at birth (fish, plants, frogs, invertebrates)

r-selected Populations

• many offspring

• very little parental care

• early maturity and short lifespan

• harsh environments

• one reproduction per lifetime

K-selected Populations

• few offspring

• lots of parental care

• long lifespan

• long maturation time

• several reproductions per lifetime

• stable environment

Eutrophic

Nutrient-rich

• low light penetration

• low biodiversity of animals

• low dissolved oxygen concentration

• high biological oxygen demand

Oligotrophic

Nutrient-poor

• high clarity

• low plant biodiversity

• high dissolved oxygen concentration

• low biological oxygen demand

Mesotrophic

the perfect in-between for nutrient levels

Primary Succession

• beings on bare rock or sand

• first soil is built by lichens

• (eg. after volcanic eruption)

Secondary Succession

• soil is present

• faster than primary succession

• (eg. abandoned crop field or after a tornado)

What are the 7 main biomes?

• Tropical rainforest

• Temperate Forest

• Tundra

• Desert

• Taiga

• Grassland

• Savanna

How do you calculate degrees of freedom?

• n - 1

• n = number of different variables/types

What is the “p” value?

• critical value for chi square

• 0.05 unless stated otherwise

What is Hardy-Weinberg equilibrium?

Allele frequencies stay constant unless there is some evolutionary force acting up the population.

• practice the formulas

Hardy-Weinberg Equilibrium Formulas

• p + q = 1

• p² + 2pq + q² _{= 1}