Bio 1b (ecology)

Population

Group of Organism's in the same species

Community

multiple populations in a particular place and time

Ecosystem

A community of organisms and their abiotic environment

Biosphere

the entirety of planet earth

life history

suite of traits related to a species' lifespan and the timing and pattern of reproduction

principle of allocation

Individual organims have limited amount of resources to invest in different activities and functions

Trade Off

resources invested in one function are not available for another

Survivorship

fraction of individuals surviving to a given age

Fast-slow continuum

a range of life history strategies from "fast", grow quickly, reproduce early, short life, to "slow" species, grow slowly, reproduce later, and long life

birth

the number of individuals added to a population through reproduction

death

the number of individuals that die in a population over a time period

immigration

movement of individuals into a population from another area

Emigration

movement of individuals out of a population to a new area

birth-death model (B-D)

a simple population model that looks at population change based only on births and deaths (IGNORES MIGRATION)

exponencial model

a model where population growth increases rapidly without limits, assuming unlimited resources

logistic model

a population model that includes resource limits, slowing growth as the population approaches carrying capacity ( S shaped curve)

per capita population growth rate

the average contribution of each individual to population growth

(population growth/ population size)

density dependance

when population growth rate is affected by population density

- more individuals -> more competition, disease, etc

Equilibrium Population Size

when a population where growth stops

(births + immigration = deaths + emigration)

Carrying Capacity (K)

Maximum population size that a particular environment can sustain

Intrinsic Growth Rate (r)

the maximum potential for growth of a population under ideal conditions with unlimited resources

Population Fluctuation

changes in population size over time due to environmental factors

Competition

(-,-)

species each use a resource that limits the survival/ reproduction of the other

Intraspective competition

competition within the same species

interspective competition

competition between members of different species

predation

(+,-)

Interaction where predator eats prey (stabilizes population)

Hebivory

(+, -)

organisms eat parts of a plant, harming it but not killing it

Paratism

(+/-)

one organism lives on or in another and harms it

Mutualism

(+,+) Both organism benefit

-ex: bee pollinating a flower

Commensalism

(+, 0)

A relationship between two organisms in which one organism benefits and the other is unaffected

facilitation

one species improves the environment for another

- general term for mutualism and commensalism

defense

traits or behaviors that protect organisms from predator or herbivores

Honest mimicry

a species accurately signals something real ( like toxicity)

dishonest mimicry

a harmless species mimics a harmful one to avoid predation

exploitation competition

Indirect competition on where individuals use up shared resources reducing availability for others

indirect mutualism

two species benefit from each other through a third species

interaction network

a syste showing how multiple species in a community are connected through interactions ( like food webs)

coexistance

when multiple species live together in the same area over time without driving the other extinct

scarcity

Limited quantities of resources (food, water, space)

fundamental niche

the full range of conditions and resources a species could use without competition

realized niche

the ACTUAL conditions a species uses due to competition and other interactions

niche overlap

When two species share similar resources or environment

niche partitioning

when species divide resources to reduce competition and allow coexistance

predator-prey systems

interactions between predators and their prey that influence each others population sizes

cycle

regular, repeating changes in population size over time

spacial refuge

an area where prey are protected from predators

fluctuation

irregular (not perfectly predictable) change in population size or conditions

disturbance

an event that disrupts a community and changes resource availability or structure

primary succession

community development starting from bare, lifeless surface

secondary succession

following disturbance to an existing community populations decline or only individuals or some life stages survive

species richness

the number of different species in a community

species evenness

how evenly individuals are distributed among species

species composition

The identity of the species present in a community

alpha diversity

species diversity within a single local area

beta diversity

the difference in species between habitats (species turnover)

gamma diversity

total difference across a large region (multiple habitats combined)

spacial scale

the physical size of the area being studied

species- area relationship

large areas tend to have more species

island biography theory

species richness in islands depends on distance from mainland (immigration) and island size (extinction)

equilibrium richness

the stable number of species where immigration=extinction

luxury effect

areas with higher income often have greater biodiversity (especially plants)

latitudinal diversity gradient

species diversity is greater near the equator and decreases towards the poles

Species Distribution

multiple factors combine to determine where a species could be present or absent

dispersal

movement of individuals away from their birthplace or population

dispersal limitations

when a species cannot reach a suitable habitat due to barriers or distance

environment

all external conditions (living and nonliving) that affect an organism

biotic limit

limits caused by living components of the environment

abiotic limit

limits caused by NONliving components of the environment

behavior

actions or responses of organisms to their environment

environmental gradient

a gradual change in environment conditions over space

climate

long term average weather condition in an area

biome

a large ecological region defined by climate and dominant vegetation

temperature

measure of heat in an environment

precipitation

any form of water falling from the atmosphere

elevation

height above sea level

latitude

distance north vs south of the equator

Hadley cell

a large scale atmospheric circulation pattern near the equator that drives climate patterns

maritime climate

influences by oceans (mild temperatures, more moisture)

continental climate

inland ( greater temperature extremes, less moisture)

photosynthesis

Process by which plants/algae use sunlight to convert CO₂ and water into glucose (food) and oxygen

respiration

Process by which organisms break down glucose using oxygen to release energy (ATP), producing CO₂ and water

Gross Primary Productivity (GPP)

Total energy captured by producers via photosynthesis

Net Primary Productivity (NPP)

Energy remaining after respiration (what's available to consumers)

Energy Flow

Movement of energy through an ecosystem from producers → consumers → decomposers

ecological efficiency

Percentage of energy transferred from one trophic level to the next (usually ~10%)

assimilation fraction

Portion of consumed energy that is actually absorbed and used by an organism (not lost as waste)

trophic pyramid

A diagram showing energy (or biomass) decreasing at higher trophic levels

trophic cascade

When changes at the top of the food chain affect multiple lower levels

Top-down control

Predators control ecosystem structure

Bottom-up control

Resources (like nutrients) control ecosystem structure

Sociometabolism

The flow of energy and materials through human societies (like an ecosystem, but for humans)

- ex: Cities using food, water, and fuel, then producing waste and pollution

Stock

Amount of a substance in a system at a given time

Flux

Rate at which that substance moves in or out

Netflux

The difference between inputs and outputs of a substance in a system

residence time

Average time a substance stays in a system

sink

Absorbs more of a substance than it releases

- ex: Forest = carbon sink (absorbs CO₂)

source

Releases more than it absorbs

- Burning fossil fuels = carbon source (releases CO₂)

Haber-Bosch Process

Industrial process that converts nitrogen gas (N₂) into ammonia (NH₃) for fertilizers

Nitrogen Fixation

conversions of atmospheric nitrogen (N2) into usable forms like ammonia by bacteria

Chemical fertilizer

human made substances that add nutrients (like nitrogen, phosphorus) to soil