EEB 211 - Midterm Flashcards

Ecology

The study of the interaction between organisms and the environment

Fundemental Niche

A description of a species’ requirements of the environment to survive

Climate

_____ is the most prominent driver of species distribution

Biomes

The major life zones defined by vegetation

Species ranges

The range of areas where species live

climate change/competition; species ranges

_____ helps shift ____, which effects where species live

Competition(*)

The term that describes the effects that two species that use a similar resource pool have on each other

Population

A group of individuals of a single species living in the same general area

Population growth

The careful accounting of population’s increase or decrease as affected by factors like birth, death, immigration, etc.

N_t+1-N_t= B-D+I-E (given births, deaths, immigration, emigration)

How do you calculate the population growth between the time t years and t+1 years?

Rate of population change

Calculated by λ= 1-b-d, given b and d are birth and death rates. Helps describe how the population changes given no immigration/emigration

Positive = growth, negative = decline, zero = no change

What do a positive, negative, or zero λ mean in regards to the population?

Multiplicative growth of population

Represented by λN_t=N_t+1, a particularly good model to account for population change in species that often have birth/death occur at discrete points in time

Continuous Birth Time Model

A model for population growth that accounts for species where at birth individuals have some chance of giving birth and dying

𝑑𝑁/𝑑𝑡 = 𝑟𝑁; 𝑁𝑡 = 𝑁₀𝑒^𝑟𝑡(given that N is the population size, t is time, and r is the exponential rate of population growth)

Continuous Time Birth Formula

Density Dependent (Logistic) Growth

A model of population growth that accounts for density (if that influences the growth rate), and accounts for a carrying capacity (K) that controls population growth

dN/dt = (r_max)(N)((K-N)/K) —> with K being carrying capacity and r_max being the max r value (or natural growth rate)

Density Dependent (Logistic) Growth Formula

When the population is half the carrying capacity (K/2)

When is rate of population growth the highest (r?)

The demographic transition

A transition/trend in human population growth/development that explains how birth and death rates vary for people based on the development of society/social factors

They eventually converge to match each other, making population change somewhat consistent over time.

For humans, what happens to birth and death rates over long courses of time

Because populations vary in terms of the individuals that make them up, including things like age, fertility, etc.

Why are N_t+1 models sometimes hard to use to predict population growth?

Stage-based model of population growth

A model for population growth that divides main demographic divisions, quantifies those divisions, and turns it into a matrix to account for population growth in accordance to demographic differences. Allows us to then calculate population changes using rates/matrices.

J_t+1=(S_j)(J_t) + (b)(A_t) —> simplified: The juveniles at t+1 is the amount of juveniles that stay juveniles plus the amount of adults that give birth

Formula for juveniles at t+1

A_t+1=(S_A)(A_t) + (m)(J_t) —> simplified: The adults at t+1 is the amount of adults that stay adults plus the amount of juveniles that mature

Formula for adults at t+1

Scotch Broom Model

A model for assessing population growth that accounts for even more stages beyond juvenile and adult, and how that may effect population numbers and changes between stages. Represents how we can add an almost infinite number of factors to this equation to describe growth.

Markage

A data collection method that tags individual to track survival, growth, and shrinkage

Estimation

A method of roughly determening offspring outcomes for given individuals in a population

Elasticity

The proportional sensitivity of λ to small changes in each matrix element (or how much a certain subset of the population effects the overall growth rate)

Dispersal

The process when offspring move away from their parents —> creating connected populations and communities

Metapopulations

Populations that are linked by processes of dispersal and migration

Colonization

The process in which an uninhabited patch of livable space gets a population introduced to it via migration/dispersal

dp/dt = cp(1-p) - mp (with m being mortality rate, c being number of colonized patch per occupied patch, and p being proportion of colonized patches) —> terms show: cp=proportion of patches being colonized, 1-p = proportion of unpopulated patches, and mp=proportion of patches that have gone extinct

Formula for change in proportion of occupied patches

p* = 1- (m/c) —> m being mortality rate and c being colonization rate

Formula for p* (proportion of occupied patches at equilibrium)

contains suitable but occupied patches (p* is always < 1)

Based on our model, metapopulation always _____

m > c; p* < 0; c>m

If ____, then ___ and the meta-population goes extinct. Persistence requires ____

Source-Sink Populations

A population dispersion pattern that involves a large, stable source population continually sends individuals to a sink population that continually heads towards extinction absent colonization

unoccupied; destroy the entire metapopulation

Destroying or eliminating the ______ patches in the metapopulation affects the

persistence of the entire metapopulation. And destroying a subset of patches can ______

dp/dt = cp(1-p-d) - mp

Formula for change in proportion of occupied patches accounting for destruction

Island Biogeography Theory

A multispecies model for source sink population that usually happens on islands. Theorizes that the mainland is large and stable enough for all species to persist and islands are small enough that all populations are headed for extinction based on their c and m values.

islands get further out; distance function related to immigration; more diverse island

Immigration rates decline as ______, indicating a ______. _____ (1) also leads to ….

Species turnover

Change in species compositions over time; usually involves the number of species staying the same but the types changing

Island Biogeography Theory - Formal

The change in the number of species on an island, S, is the balance between the species-level immigration rate and the extinction rate. Formal definition for this theory.

S*

The equilibrium # of species on an island, using the extinction and immigration rate on the species level.

Predation

When a species kills and eats another

Herbivory

When a species eats part of a plant/algae

Competiton

the process by which species harm one another via the use of shared resources

Parasitism

An interaction where one species derives nourishment from a host

Trophic interactions

Interactions between species that involve one species eating/deriving energy from another

Community

A group of interacting populations of different species

Bottom-up control

Where lower level trophic organisms control the abundance of higher ones

Top-down control

Where higher level trophic organisms control the abundance of lower ones

As you go up and add layers, constrains on lower layers get relieved, meaning generally speaking, higher levels are bottom up controlled whereas lower levels are more top down controlled. Layers alternate between being controlled by predation/herbivory and resources.

Describe the general dynamics that occur with bottom-up and top-down control within ecosystems

Productivity of basal trophic levels

The biomass produced by producers; a certain level of this is needed to support the existence of higher trophic levels

Trophic cascade

an interaction where predators suppress the abundance of their prey, thereby releasing the next lower trophic level from predation or herbivory

Keystone Species

Species that exert large control on communities despite low abundance

Lotka Volterra Model

A model of competition that looks at how different species harm one another, but does not specify the mechanism through which harm arises. Generally useful for understanding how competition comes to be

Give the equation of how the logistic model of population growth can account for competition

α

Represents the harmful effect a species has on either its own or a differing population; calculated by 1/K (carrying capacity)

The species with the outer isocline would outcompete the species with the inner isocline

What is the competitive outcome if one species’s density isocline in fully within another species’s isocline

Mutual Invasion Condition

The condition that asks if both species can increase when their competitor is common. If one can and the other can’t the one that can is likely the dominant species.

Better tolerating their neighbors

Species win in competition by _____

Interspecies competition

The type of competition that occurs between species; is the greatest when one species is dominant over another

Disturbance

A discrete event that removes organisms from the environment and alters resource availability (ex: storms, floods, etc.)

Succession

The change in species composition over time —> stages described by dominant species

Facilitation

The model of succession in which early species better tolerate the physical environment and modify it in ways that make it tolerable for later species to thrive

Inhibition

A model of succession where early and later species compete, with later species ultimately winning out in the end

Tolerance

A model of succession where change is determined by differential rates of colonization, and earlier species do not have any substantial effect on later ones

Co-existence

A state in the Lokta-Volterra model where isoclines cross in such a way that you get the stable co-occurence of species in the same general location; occurs when both species can fulfill the mutual invasion condition and intraspecies competition outweights interspecies competition

When the intraspecies α values are greater than the interspecies ones —> i.e. the species exert more pressure on their own competitions than they do on others

Under what conditions of α does co-existence occur?

Resource Partitioning

When different species within the same community use different resources; often results in co-existence between the species

Alternative stable states

A state in the Lokta-Volterra model where both interspecies competitions outweigh each other, leading to the unstable equilibrium condition where one species wins out based on which population is larger at first. In this state neither species fulfill the invasion condition.

SIR Model

A model for assessing disease dynamics which looks at members in a population as susceptible to disease, infected, or recovered/immune from the disease

Transmission Rate

Number of contacts sufficient to spread the disease that an infected individual has per unit time (β)

Recovery Rate

The probability of recovering per unit time (γ)

Describe the three main equations that describe disease dynamics/changes in relevant disease populations

R₀

The number of infected individuals that get infected by each infected individual during their infectious period —> described by β/γ given an entirely susceptible population; must be greater than 1 for the disease to get going

Herd Immunity

Immunity at the population level that arises due to the immunity of a subset of the population

V (Vaccination proportion)

Describes the fraction of the population that needs to be vaccinated/immune in order for infections to decline/R₀>1. Calculated by 1-1/R₀

Biodiversity

Variation that is found on the genetic, species, and ecosystem levels

Cambrian Explosion

The point in ecological history when multicellular organisms started to appear

speciation (species coming in); extinction (species dying out)

Species richness is a balance found between _____ and _____

The tropics; since it is theorized that their climate has been static for longer

Where is diversity generally better? Why?

Diversification rate

Calculated via λ-μ (speciation minus extinction)

Land use change (terrestrial), exploitation (marine)

What are the main drivers of biodiversity loss in terrestrial v. marine ecosystems?

Niche Complementarity

The idea that more diverse systems make use of resources better because component species differ in their niches

Polyculture and Monoculture

Terms for environments with multiple and one predominant species(or plural) respectively

Selection Effect

The idea that in some diverse systems, there are “high function” species present that ultimately dominate the outcome of the polyculture, with no substantial complimentary effects occurring

Portfolio effect

The aggregate biomass of a diverse set of independently fluctuating species shows less variability over time than will a species poor set (or monoculture) —> usually occurs when species have negative correlations in production/some species are better under certain times/conditions compared to others

Dilution Hypothesis

Disease establishment is more difficult in more diverse communities as host species become rarer and transmission becomes more difficult

The Carbon Cycle

Involves the cycling of carbon through land and water; fueled by the natural ability for plants to take in carbon via CO2 and internal cycling in the ocean

Cellular Respiration

The process that releases CO2 back into the atmosphere by living organisms to help power their cells

Methane (CH4)

A chemical compound released by microorganisms in the low-oxygen conditions of wetlands it eventually breaks down into CO2

The soil

The biggest carbon dump is _____

The Greenhouse Gas Effect

A driver of climate change that involves increased CO2 reflecting usually lost sunlight back onto the earth, creating a positive feedback loop that increases vaporized H2O which also has the same effect.

Deforestation

_____ also contributes to increased CO2 in the atmosphere by increasing the decomposition of dead trees

Permafrost

A layer of soil below the freezing point of water that holds a bunch of carbon; it is as risk of melting due to climate change, which would only accelerate temperature increases even more

Land and ocean uptake

_________ serve as a natural CO2 sink, which helps sequester increased CO2 levels

CO2 Fertilization

When photosynthesis is limited by CO2 concentration; increased CO2 emissions/levels have allowed plants to grow more/have longer growing seasons by going around this

future emissions (also maintenance of natural sinks and use of negative emission technologies/plant reliability)

The biggest determinant of future climate change is _____

Reforestation/aforestation

A method of combating climate change that involves replanting forests/planting new forests to account for increased CO2 emissions