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 ]