Population DynamicsTerms

Habitat- an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism

Species- taxonomic group whose members can interbreed

Population Size (#/area)- number of individual organisms in a population

Crude density- The number (or biomass) per unit total space

Ecological density- the number (or biomass) per unit of habitat space (available area or volume that can actually be colonized by the population-where organisms exist)

Population Dispersion- the general pattern in which individuals are distributed through a specific area

ClumpedRandomUniform

Mark-Recapture SamplingM/N=m/n

Example: There is a fish population of unknown size in a lake. 26 fish are captured, marked, and released back into the lake. After 10 days 21 fish are captured of which 3 are marked...How do we use this information to figure out the population size?

Answer

Carrying Capacity- population size of the species that the environment can sustain indefinitely, given the food, habitat, water and other necessities available in the environment.

Factors that affect Population GrowthPopulation dynamics- changes

in population characteristics determined by natality, mortality, immigration, and emigration

Fecundity- the potential for a species to produce offspring in one life time

Factors that affect Population GrowthNatality- birthrate: the ratio of live births

in an area to the population of that area; expressed per 1000 population per year

Mortality- deathrate: the ratio of deaths in an area to the population of that area; expressed per 1000 per year

Emigration- migration from a place (especially migration from your native country in order to settle in another)

Immigration- migration into a place (especially migration to a country of which you are not a native in order to settle there)

x 100

Closed Population- A population that is closed to genetic material from the outside (zoo)

Open population- a population that is open to genetic material from the outside (forest)

Biotic Potentialthe maximum rate a population

can increase under ideal conditions

Biotic PotentialBirth potential- maximum

reproductive capacity of a population if resources are unlimited. Full expression of the biotic potential of an organism is restricted by environmental resistance, any condition that inhibits the increase in number of the population.

Capacity for survivalProcreation- the sexual activity of

conceiving and bearing offspringLength of reproductive cycle

Geometric Growth FormulaN(t+1)=N(t) λ

Exponential Growth: Formula

If a population has a constant birth rate through time and is never limited by food or disease, it has what is known as exponential growth. With exponential growth the birth rate alone controls how fast (or slow) the population grows.

dN / dT = rN

http://www.otherwise.com/population/exponent.html

Logistic GrowthIn most real populations both food and

disease become important as conditions become crowded. There is an upper limit to the number of individuals the environment can support. Ecologists refer to this as the "carrying capacity" of the environment. Populations in this kind of environment show what is known as logistic growth.

dN /dt = rmaxN[ (k-N) / k ]http://www.otherwise.com/population/

logistic.html

Logistic Growth

1. Lag Phase2. Log Phase3. Stationary Phase

1

2

3

Environmental Resistance- All biotic and abiotic factors combining to limit explosion

Dynamic Equilibrium- lack of change in a system as inputs and outputs remain in balance. If changes do occur, then feedbacks will allow for correction

Density Dependent factor- factor that influences population regulation, having a greater impact of population density increases or decreases

Density Independent factor- factors that influence population regulation regardless of population density

Competition Intraspecific Competition- when a

species competes against other members of their own species. Competing for space, mates, food/water, and shelter.

Interspecific Competion- interactions between individuals of different species for an essential common resource that is in limited supply. Competing for space, food/water, and shelter.

Interspecific CompetitionInterference-interspecific

competition that involves aggression between individuals of different species who fight over the same resource(s). Eg, birds of the same size over a bird house

Interspecific CompetitionExploitation-interspecific

competition that involves consumption of shared resources by individuals of different species, where consumption by one species may limit resource availability to other species. Eg, zebra muscle

Interspecific CompetitionResource Partitioning-

avoidance of, or reduction in, competition for similar resources by individuals of different species from reproducing successfully together; sharing of a resource, plant root depth

Predator Prey CyclePredator Prey Relationship:

An interaction between two organisms of unlike species in which one of them acts as predator that captures and feeds on the other organism that serves as the prey.

Echo effectLynx-hare-hares increase, lynx

increase

Predationpredator (an organism that is

hunting) feeds on its prey (the organism that is attacked); Capturing a prey as a means of maintaining life.

Example: Lion and cub eating a Cape Buffalo

Predator: any animal that lives by preying on other animals

Prey: the animal being hunted

Predator

Prey

Co-evolution- When two species influence one another’s evolutionary history.

Bumblebees and the flowers they pollinate have coevolved so that both have become dependent on each other for survival.

Allee Effect- density dependent phenomenon that occurs when population cannot survive or fails to reproduce enough to offset mortality once the population density is too low; such populations usually do not survive

Minimum viable population size

Passenger pigeon

Ecological Nichean organism’s biological

characteristics, including use of and interaction with abiotic and biotic resources and assimilate the wastes produced by a human population

Ecological NicheFundamental Niche- the biological

characteristics of the organism and the set of resources individuals in the population are theoretically capable of using under ideal conditions; hawks predator on mice.. But day/night...

Realized Niche-more specific in that this sparrow might only eat mosquitoes, lives in top of the tree...more specific because of competition *TIE*

Camouflage A method organisms use to

disguise and conceal themselves from the surrounding environment for protection as well as attack their prey.

It is a form of mimicry

Camouflage Camouflage is a form of

adaptation to the environmentPrevents animals from becoming

another animal’s prey and makes it easier to find food

Increases chances of survival therefore chances to reproduce

Being able to camouflage is an advantage

Types of Camouflage

Blending into surroundings.Colour change. [Some animals

developed a special adaptation that allows them to change their coloration when surrounding changes (changing of the seasons)]

Disguising Animal’s Body◦Does not hide presence ◦The animal’s appearance represents an

object from its surroundings

Mimicry When a group of organisms have

evolved to share common characteristics with another group or the environment.

MimicryBatesian mimicry is when a

harmless species imitates a dangerous species and therefore, this causes the potential predator to leave the species alone.

Example: the viceroy butterfly (top) appears very similar to the noxious tasting monarch butterfly(bottom).

MimicryMüllerian mimicry is when two

harmful species mimic each other in their external appearance to scare away predators.

DefenseActive:

◦Physical-porcupine◦Chemical-poison; tree frog

Passive◦Hiding◦Camouflage◦visual warning◦Mimicry

SymbiosisInteractions in which two species

live closely, often with a physical association.

Symbiosis: ParasitismBeneficial to one species, but

harmful to the other...Microparasites: Microscopic, rapid reproduction.Examples:

◦Plasmodium a blood parasite causes malaria.

◦Trypanosoma causes sleeping sickness.

Symbiosis: ParasitismEndoparasites:Lives inside the body of their

host.Example:

◦Tapeworms.

Symbiosis: ParasitismEctoparasites:Live and feed on the outside

surface of their host. Examples:

◦Fleas, ticks, lice.

Symbiosis: ParasitismSocial Parasites: Manipulate the social behaviour

of another species to complete their life cycle.

Example: ◦Brown headed cowbird

Symbiosis: Mutualisminteraction is beneficial to both

species.Obligatory MutualismNeither organism can grow or

reproduce without the other.Examples: Beneficial bacteria in

the large intestine of humansExamples: The Red-billed Oxpecker eats ticks on the impala's coat

Symbiosis: CommensalismInteraction that is beneficial to

one species, but the other species is unaffected.

Rare in nature

ALL Formulas Population Density:

◦ D= N/S Average sample density

◦ [total number of individuals ] / [total sample area] Estimating population size using mark-recapture

sampling◦ N= Mn/ m

Population Change

◦{[(B+I)-(D+E)] / N } X 100 Geometric Growth:

◦ N(t+1)=N(t) λ Exponential growth

◦ dN / dT = rN Logistics Growth

◦ dN /dt = rmaxN[ (k-N) / k ]