inheritence, variation and evolution

3 reasons for differences

• genetics causes

• environmental causes

• combination of both causes

what is variation due to

mutation

how do mutations effect phenotype

• most have no effect

• some influence

• very few change

evolution is

• the change in inherited characteristics of a populaiton over time.

• this is through natural selection, which can eventually form new species

when did simpler life forms first develop

more than three billion years ago

a species is

a group of organisms with similar characteristics which can reproduce to produce fertile offspring

which 2 scientists proposed theory of evolution by natural selection

charles darwin, alfred russel wallace

charles darwin famous for work on

finches in galapogos islands

wallace famous for research on

warning colouration and speciation

4 steps of natural selection

1. genetic variation in a characteristic in a species due to a random mutation

2. those with characteristic best suited to the environment are more likely to survive and reproduce

3. pass on beneficial alleles for that characteristic to their offspring

4. the frequency of the beneficial allele increases in the population over time.

3 reasons why natural selection was not accepted initially

• strong religious beliefs

• insufficient evidence (no microscopes)

• mechanism of inheritence not known till 50 yrs later

lamarck’s theory

inheritance of acquired characteristics over a life time,

if an individual needs to adapt it will, and pass on to offspring

4 main steps for speciation

1. isolation

2. mutation

3. natural selection

4. speciation

isolation is…

geographical/physical barrier that seperated population

mutation for speciation…

creates new alleles and variation in each population

natural selection for speciation

• in different environments, different selection pressures

• those best suited to new environment survive and reproduce

• pass on beneficial alleles to offspring

step 4 = speciation

after a long time, populations are so different they can no longer interbreed to produce fertile offspring, they are different species

2 evidence for darwin

1. fossils

2. antibiotic resistence in bacteria

what are fossils

remains of organisms from millions of years

conditions for fossil preservation (one or more present)

• NO oxygen

• LOW temp

• DRY

• LOW ph (denatures enzymes)

what fills space after organism decays

minerals

what are some traces of organisms

foot prints, burrows, rootlet traces

why are early life forms not found as fossils

• soft bodied, decay quickly

• traces destroyed by geological condition

5 abiotic/physical reasons for extinction

1. drought

2. global warming

3. volcanic activity

4. asteroid/meteor impact

5. ice age

5 biotic factors for extinction

1. new predators

2. new disease/pathogens

3. increased competition for food

4. increased competition for mates

5. lack of habitat/habitat change

who is classification system named after

carl linneaus

order of groups in hierarchical system

1. kingdom

2. phylum

3. class

4. order

5. family

6. genus

7. species

how to write genus?

Captial letter

species is __ name

binomial , lowercase

three domain system by carl

woese

archaea =

primitive bacteria (extremophiles)

bacteria

true bacteria

eukaryote

plants, animals, fungi and protists.

4 reasons for changes in classification

• better microscopes

• better understanding of biochemical processes

• dna sequencing

• studying evolutionary relationships over time.