Unit D - Biology 30: Mendelian Genetics & Populations

species

a group of organisms capable of interbreeding and producing fertile offspring

population

all the members of the same species occupying the same area at the same time

community

all the different species that are found within a given habitat

ecosystem

a group of living organisms that interact with their non-living environment to form a self-regulating system which energy and materials transfer

ecological niche

functional role of a species in its habitat including all the biotic and abiotic factors under which a species and live and reproduce

population size (N) (3)

* number of certain species in a given habitat at a given time
* usually based on approximate numbers from sampling
* N = original population size

population density (2)

* number of species per unit of space
* equation: Dp= N/A or Dp=N/V

natality (2)

* (+)
* number of species born in one year

mortality(2)

* (-)
* number of species that die in one year

immigration (2)

* (+)
* number of individuals of a species that move into a given population

emigration (2)

* (-)
* number of individuals of a species that move out of a given population

calculating the change in population size (2)

* ΔN
* Change in population size = (birth + immigration ) - (death + emigration) or = (final population) - (initial population)

per capita growth rate (4)

* shows the rate at which a population is increasing or decreasing
* cgr = ΔN/N (can also be expressed as a %)
* increasing = (+) rate
* decreasing = (-) rate

what is learned from cgr?

scientists can track the development of a species and exam what enviormental factors may be causing the change

dynamic equilibrium

most mature ecosystems are able to remain stable over the long term within fluctuating limits

calculating population growth (2)

* growth rate in population


* gr = ΔN/Δt

open populations

when all four population factors can occur and effect density

closed populations (2)

* when immigration and emigration are controlled
* population changes only by natality and mortality

lag phase

adjustment period prior to accelerated reproduction by the population

growth phase

fastest population increaseoften seen in microorganisms who reproduce with binary fission causing exponential growth

stationary phase (3)

* equilibrium between natality and mortality because the same amount are born that die
* stabilizing at the carrying capacity
* limiting factors (food/space) begin to run out

death phase

nutrients run out and waste accumulates

close population growth curve

j-shaped or exponential growth curve - the population rises very quickly and quickly drops

open population growth curve

S-curve or logistic curve

carrying capacity (K) (2)

* max population that can be sustained by a given supply of resources


* the balance between biotic potential and environmental resistance is what creates this.

limiting factors (2)

anything that limits a population from growing larger not enough food, energy, space, water, more predators, disease

density independent limiting factors

factors that affect members of a community regardless of population density (flood, fire; usually abiotic)

density dependent limiting factors

factors arising from population density that affect members of a population (food, water, space; usually biotic)

biotic potential (2)

refers to theoretical max birth rate of a population

what is biotic potential determined by? (4)

* offspring - max number of offspring
* capacity for survival - chances the offspring will reach reproductive age
* procreation - # of times per year the organism can reproduce
* maturity - age at which repro begins

environmental resistance (3)

* all the limiting factors in the environment that work to decrease population size
* limiting factor that controls pop. size will change constantly
* Major resistances include predation, disease, competition for space, food, habitat etc.

r selected populations (5)

* high biotic potential (rapid development, many small offspring)short life span (usually reproduces once in a lifetime)
* exponential growth curves (more death phases, dramatic population size changes)
* parents don’t care for young
* small grasses, mosses, shrubs

K selected populations (5)

* low biotic potential but lives at carrying capacity (slow development, few, large offspring)long life spam (usually
* reproduces more than once in a lifetime)
* logistical growth curves (infraspecific competition, little population change due to seasons)
* parents care for young
* ex: mature trees found in an ecosystem

symbiosis

two organisms that have a close relationship

parisitism (2)

* one benefits and one is harmparasites get nutrients from host
* \*\*generally do not kill the host (\*\*ex: bunny nibbling on a lettuce leaf)

commensalism

one benefits and one isn’t harmed

mutalism

both organisms benefit

interspecific competition

competition among similar species for resources

intraspecific competition

competition within a niche between members of the same species

predator-prey relationships (3)

* one organism eats another
* when prey population increases the predator population also increases
* causes an exponential (j-shaped) growth curve for the predator

producer-consumer relationships

a relationship between a plant and an organism that feeds on a plant

parasitism (2)

* when a grazer consumes the leaves of a plant but not the roots, the plant doesn’t die because it regenerates the roots
* because the plant does not die, it’s considered this

predation

if an organism were to consume all parts of the plant, leaving the plant with no means of reproduction and leading it to it’s death

mimicry

animals that evolve similar patterns to another species to gain survival advantage

protection from predators (4)

* camouflage (blend into the environment)
* mimicry (animals that evolve similar patterns to another species to gain survival advantage)
* physiological adaptations (ex: the lizard squirting blood against a predator)
* active behavioral defense (ex: running)

radio telemetry (2)

* attatching radio transmitters to animals and then putting them back in the wild
* can study travel habits, heart rate, etc

what are technologies of population studies?

radio telemetry and capture-tag-release-recapture

capture-tag-release-recapture

allows you to determine population size and see how well the species is surviving

sucession

changes in plant and animal populations between colonization and the finaly community

primary succession

occurs where no plants have lived before (sand dunes, lava flows, bare rocks, retreating glacial areas)

secondary sucession

occurs after a natural community has been disturbed (fire, avalanche, earthquake, logging, mining)

what is succession of an ecosystem dependent on?

abiotic factors of that ecosystem

when does succession occur?

as new populations occupy available niches

climax species

mature species

pioneer community

first species to appear after successionex: lichen, moss, insects, smaller plants

sereal stages

specific stages in succession identified by the dominant species presentannuals, shrubs, pioneer trees, intermediate trees

climax community

final relatively stable community reached during successional stagesclimax forest tree species as well as plants and animals from seral stage

population

all the members of the same species occupying the same area at the same time

population genetics (2)

* examines genetic variation within and between populations and changes in allele frequencies across generations
* population geneticists use math models to investigate and predict allele frequenices in populations

evolution

any allele frequencies for a particular trait that’s changing overtime shows the population is experiencing this

gene pool

consists of all the genes in an interbreeding population

what ensures variation of organisms in gene pools?

repro does

Hardy-Weinberg Principle

"if all other factors remain constant, the gene pool will have the same composition generation after generation”

Hardy-Weinberg equation criteria (*mattn) (6)

1. no mutations occur
2. there is no net movement of individuals
3. the population is large
4. mating is random
5. all alleles are equally viable principle suggests that over time the percent of each allele should remain constant

what genes does the Hardy-Weinberg equation deal with? (3)

* two alleles where one is dominant and one is recessive
* together make AA, Aa, aa which all = 100%
* A + a = 100% (p + q = 1)

Hardy-Weinberg equation

p^2+2pq+q^2 \= 1(AA + 2Aa + aa) \= 1

what happens if a population meets all 5 Hardy-Weinberg criteria?

it should remain in equilibrium over generations

agents of change in Hardy-Weinberg’s criteria

mutationgene flow (migration)genetic driftfounder effectbottleneck effectnon-random matingnatural selection

natural selection (agents of change) (2)

* some alleles are more viable in a particular environment result in an increase in their frequency in the population
* can create differences between populations in different locations

non-random mating (agents of change)

when choice of mate is based on some sort of selection criteria

bottleneck effect (agents of change) (2)

* genetic drift example; a dramatic, often temp. random **REDUCTION IN POPULATION SIZE** that can change the population composition as only a few members survived
* creases genetic diversity

founder effect (agents of change) (3)

* genetic drift ex: where a small group of the population breaks off (new island forms, people move off into isolated areas 2 start their own small pops., etc)
* new pop is established by a very small #’s of individuals from a larger population
* decreases genetic diversity

genetic drift (agents of change) (3)

* a change in a gene pool that takes place as a result of chance (accident, a fluke) (change is not natural selection related)
* usually observed in small populations where a small shift in an allele frequency has a major effect on the population
* more common in neutral genes (unnecessary for survival)

gene flow (agents of change) (3)

* aka migration + is the movement of genes into or out of a population resulting in changing gene frequencies
* decreases differences within populations“where i go my genes will flow”

mutation (agents of change)

changes in genetic makeup of an organism which can be spontaneous or caused by mutagens in the environment

what happens if there’s a change? (2)

* if agents cause a change in gene frequency we say that evolution is occurring
* these selective pressures that cause population to change can accumulate and if enough changes occur over time, a new species will form (**SPECIATION**)

phenotype

refers to the observable traits of an organism (ex: brown hair, purple flower)

alleles

versions of genes

genotype

refers to the alleles an organism contains (the genetic make-up)

homozygous (2)

* genotype in which both genes in an individual are the same
* genotypes can be homozygous dominant (TT) or homozygous recessive (tt)

heterozygous (3)

* genotype with different gene pairsone gene is dominant
* (T) and one gene is recessive (t)


* the dominant gene is the phenotype that’s expressed

autosomal

autosomes are any of the chromosomes that aren’t sex chromosomes (in humans that pairs 1-22)

sex chromosomes

in humans this pair 23female are XX, males are XYtraits on X chromosomes are “X-LINKED”

x-linked

traits on the X chromosomes

who’s gregor mendel?

* a monk who first suggested that genes are how our traits are inherited (1857)
* did research with pea pants because they can cross or self fertilize and show very distinct physical characteristics

mendel’s law of heredity

1. all genes occur in pairs
2. law of dominance
3. law of segregation
4. law of independent assortment

all genes occur in pairs (3)

* each organism that reproduces sexually has two copies of each gene
* one from egg and one from sperm
* these pairs of genes are found in the same locus (location) on a homologous pair

law of dominance (3)

* a dominant allele will mask the expression of a recessive allele if an organism inherits both
* Dominant Allele - procedures the same characteristic where its paired with an identical allele or not (written as a capital letter (T)
* Recessive Allele - genes that overruled by dominant genes and is written by lowercase letters (t) (in order for a recessive to be appear-ent both genes must be recessive)

law of segregation

* in anaphase I of meiosis, pairs of genes separate when their homologous pair separates


* each gamete produced contains one copy of the gene and it’s random which gene each gamete gets

law of independent assortment

* the alleles of two different gene pairs get sorted into gametes independently of one another
* the allele a gamete receives for one gene pair doesn’t influence the allele received for another gene pair
* this is because homologous pairs ignore all other homologous pairs when they line up in metaphase I

punnett square

a chart used by geneticists to show the possible combinations of different forms of genes (alleles) in offspring

if all offspring could be heterozygous, what genotype are the parents?

homozygous recessive and dominant.

if all offspring could be a 1:2:1 ratio, (YY,Yy,yy) what genotype are the parents?

both heterozygous

if all offspring have a 1:1 ratio (heterozygous and homo. recessive) what genotype are the parents?

heterozygous and homozygous recessive

if all offspring have a 1:1 ratio (heterozygous and homo. dominant) what genotype are the parents?

heterozygous and homozygous dominant

test cross (2)

* used to determine the genotype of an organism that expresses the dominant phenotype (homozygous dominant or heterozygous)
* cross the unknown genotype with a homozygous recessive phenotype

multiple alleles

sometimes there are more than 2 alleles possible for a certain trait (use upper case letter to represent the trait and # to represent the different alleles) (E^1)

incomplete dominance

one allele doesn’t dominate over the other allele causing the heterozygous offspring proceeded to express a **BLENDING** of the two alleles inherited

codominance

pattern of gene expression in which one allele doesn’t dominante over the other allele causing the heterozygous offspring produced to **SHOW BOTH PHENOTYPES**

how many different marker types are on the surface of our RBC’s?

30, these come from 35 different genes with over 600 known alleles