Population + Community Dynamics

Adaptation

allows an individual to survive better in a given curcumstnace.

Growth rate

how much a population has increased/deacreased in a set amount of time
change in population number divided by change in time (final- initial) (f- i)

Communities are made up of ...

populations.

Density

number of individuals per unit of space

parasitism

one organism benefits at the expense of the ohter.

The frequency of alleles and the genotypes in a population would remain constant form generation to generation IF the population is ...

stable and in genetic equilibrium.

Species

a group of similar organsims* can interbreed, and produce fertile offspring, exists in the natural environment.

disrupt genetic equilibrium

Large breeding population- helps ensure chance doesnt ...

Speciation

(initial) seperation of a species.

Population

a group of similar organisms in the same place at the same time

Species

a group of similar organsims *can interbreed, and produce fertile offspring, exists in the natural environment

Adaptation

a variation that allows an individual to survive better in a given curcumstnace

Evolution

ANY CHANGE in the frequency of a gene/allele

True

T/F large breeding population ... helps ensure chance doesnt disrupt genetic equilibrium

p

frequency of dominant alleles

q

frequency of recessive allele

p2

frequency of homozygoes dominant individuals

2pq

frequency of heterozygous individuals

q2

frequency of homozygous recessive individuals

1 =

the whole population

Adaptive

leads to favourable adaptation in a particular environment

change in genetic makeup

allelic frequency is altered

not adaptive

completely random

bottle neck effect

some disastorous event causes great reduction in genetic variabilty

founder effect

smaller population branches from a larger one

evolution

change in gene frequency

speciation

(initial) seperation of a species

symbiosis

reltionships/close relationship between different organisms

Mutualism

both organisms benefit

Commensalism

one organism benefits, th eohter is indifferent

parasitism

one organism benefits at the expense of the ohter

interspeceific

organisim competes with a different species for the same limited resource

intraspecific

organism competes wiht the same species for the same limited resources * the more similair the niche, the more competition

Gausees Principle

"competatice exclusion priinciple" if populaitons of organsims occupy the same niche, 1 will be less fit, food space, mates

predator

consumes a living organism, benefiting itself, but reducing the survival of its prey

prey

organism often consumed (results in death or reduces fertility)

Passive avoidance mechanisms

camoflauge, mimicry, warning, colouration, plant defene, toxins and poisons

Active avoidance mechanisms

movement, physiological (structural), socials

natality

number of individuals born annually

mortality

number of deaths in a species annually

immigration

movement into an existing population

emmigration

movement out of an existing population

Clumped

Individuals grouped in patterns or clumps (Trees clumped around a water source)

No real pattern, not very common, biotic or abiotic factors are iether in abundance or have little effect

Random eg, Dandelions where the sind blows

Uniform

all individuals are evenly spaced apart, often happens when there is competition for resources

shelfords law of intolerance

too much or too little of an essentail factor can be both harmful or

Density Dependant

factors which affect a popilation as a result of its density eg, starvation, preditiation, disease

density independant

factors that affect a population regardless of its density eg, flood, fire, temperature, precipitation

environemental resistance

all facotrs (or the sum of ) that limit the population growth, biotic or abiotic

Biotic potential

maximum number of offspring prodced in ideal conditions (optimal rate of approach)

Dynamic equilibrium

long term balance in which populations remain relatively stable

carrying capacity

number if organisms an ecosystem can sustain given its current capacity (k)

lag phase

slow initail growth

growth phase

exponentail accelerated growth

stationary phase

factors limit growth , flat part. natality = mortality

equilibrium phase

population fluctuates around carrying capacity

death phase

mortality exceeds natality

S shaped curves

Logistic curve, stabalize at K, has a new K, energy focused on on develpment of a few young, "K strategist" long life spans, long parental care, humans, bears, elephants

J shaped curves

rapid growth exceeding K then sharply declines, characteristic of "r strategist", shorter life spans, faster to mature, plants, insects, mice

population histograms

analyze populations based on age and gender, determine if the population is stbale, growing, or declining

problems with over population

food availibity, space, deforestation, desertification, energy, pollution, stress, erosion, invasive species,

better human affects

preservation, genetic tech (GMO crops)