AP Bio unit 7 : Natural Selection.

Natural Selection

Natural Selection

• developed by charles darwin

• organisms with favorible trait will survive and produce offspring and pass the good traits

  ex: peperred moths, antibiotic resistance (adaptive melanism)

• mutations will create new variants

Artificial Selection

• organisms with certrain traids are bred

• like dog breeds, or corn

• known as selective breeding

Types of Selection

stabalizing

diversifying or distruptonal

directional selection

Hardy-Weinburg

states

means no change in allele frequency in the gene pool

• large population - can hide mutations and genetic drift and maintains

• no genetic drift -

• random mating

• no natural selection

• no gene flow - no new alleles

Hardy Weinburg Equations

p = freuqnecy of dominant allele

q = frequency of ressesive allele

p²= freqency of homozgous dominant

q²= freqneucyt of the homozygous resseive

2pq = freqnecy of honmozygous resseisve

p+q=1

p²+2pq +q²= 1

Equation to determine equillibrum

if whave a population and we want to know if its evolving.

Find allele frequency by adding and stuff

input the data into the hardy weinburg

multiply the genotype freqenices and the total popultion

if it matches, its in equillbrium, if not, then not in equillibrum

Equation to find others

if we know the frequency or population of some

we can use that info to determine the others if the population is in equillibrum

what does it mean when a population evolved

it means that the genotype and allele frequncies change in a gene pool

this may be due to mutations, natural selection, a genetic drift,

Founders Effect

Small population is isolated from orignal population → different allele frequencies

genetic drift

Bottleneck Effect

population is reduced by a natural disaster like a fire flood, hurricane

selection is not based on traits (Lucky)

can reduce gnetic diversity and make harmful alleles more pelavent

phylogentic/ cladogram tree

the one of with most differneces (outgroup) first

nodes can switch (keep that in mind)

the closest ones are together

Speciation

creation of speicies

serperated by reporuductive barriers

2 different speices cannot interbreed and cannot produce fertile, viable offsrping

Prezygotiac Barriers

prevent formation of the zygote in the first place

Behavioral - different mating rituals (dance, song)

Temporal - mating at different times of year, day, etc

Geographic- separation by geopgraic barrier

Habitat/ Ecoligocal - organisms use different things of the same geographic area (bees on different plants)

Mechincal - the morphology wont let the pipe go in, or sperm cant reach

Gametic - molecular mismach

Post Zygotic Barriers

Species can mate and form a zygote but their offspring is not viable

Reduced Hybrid Viability - the hybrid is not viable, and sick and not fit

Reduced Hybrid Fertillity - the hybrid is not fertile (mules cannot repdocue bc odd)

Hybrid Breakdown - the first hybrid generation is ok but as the generations pass, the viability and fertility goes down

Sympatric Speciation

New speicies froma surivving speices and both still inhabit the same geogrpahic reigion

habitat and behavioral isolation

sexual selection

polyplody (error in meosis)

allopatric Speciation

geographic changes cause isolation

can cause genetive drift

spliting off gene pools

Species spread, barrier is made, the differences cause differentiation and then leads to no possible interbreeding

sources of genetic variation

Molecular

Point Mutations - Frameshift, Nonsense, Missense, → change in nueclotide sequences which changes the amino acids → protein structure → phenotype or gene expression

Duplication - genes, chromosomes, genomes, sypatric speciations → causes an extended genome or in ploidy. → altered gene number

rearrangements- sometimes gene order, inversions, chromosomes fusion, transposons → alerted chromosome structure

Other: fast reproduction (especialy in virusus)

lack of repair of DNA in virus

Genetic Variatiopn - Cellular or Repdouction

Crossing Over

Indepdent Assortment

nondisjucntion

Random Mating

Created many dfiffent gamete combinations and diversity

Genetic Variation - Population

Genetic Drift -

• Bottleneck → change in allele frequencies

• Founders Effect - New population

Gene flow - migration, leads to new types of genes, could be individuals or gametes

Geographic Isollatioj or Allopatric Seperation - seperated populations

Nonrandom mating

Sympatric Speciation - same enviroment but diffrent niche or habitat overtime

mutations

Ways to determine phylogeny of organisms or evidence of evolution

Fossils - morphology- shape, can show the common ancestors and the “in between”

Embryonic- some features and similarities are only seen before full development

Reproduction

Molecular Biology or Biochemical comparisons - DNA sequence Protein sequencing, , DNA is best because it can show specific sequences and been silent mutaitons

Morphological - homologous structures (not the most accurate because if analogous)

Biogeography - uses the distribution of species. Unrelated species can look alike due to similar pressures

Homologous vs Analogous structures/ etc

Homologous structures - from same ancestors, can be structures or proteins like insulin

• can be useful or vestigial (non useful)

Analogous structures- not from same ansestors but similar function due to similar pressures (convergent evolution)

Convergent evolutiona

Evolution which causes species to be similar and have similar traits due to similar pressures

→ analogous structures

on a cladogram, the animals will not be close

Divergent evolution

Bacially

Speciation

Polyploid

a condition in hwich an organism has extra sets of chromosomes

this leads to more

This can lead to sympatric evolution

It can occur due to abnormal cell division (non disjunction), such as when chromosomes don't separate during meiosis, or when an egg is fertilized by more than one sperm.

Autopolyploid - same species

Allopolyploid - species interbreed and produce a hybrid → sterile but can reproduce asexually (plants) → leads to fertile new species

sexual selection

male compeition (intrasexual selection)

or female choice (intersexual selection)

what is measure of fitness

the ability to reproduce

gene flow

is the trading of genes between different populations

adaptive radiation

one parent speices produces many decandant species with unique adaptations and niches

example is the galapagos birds

pseudogenes as evidecne for evolution

non functional gene that is a variant of a gene from related species

all living thingsd have

DNA

ATP - chemiosmosis

Genetic Code

Ribosomes

Metabolic Pathways like glycolysis, krebs ETC

evidence that all of Earth’s organisms are descended from a common ancestor

-all organisms even bacteria use ATP

-DNA is used as genetic code

micro vs macro evolution

-micro: small changes or adaptation, for example, bacteria evolving to be resistant to antibacterial

-macro: is the big changes in evolution that results in vastly differnt and new spceies