Evolution

DNA

• Deoxyribonucleic acid

• It consists of nucleotides

  • They are made of: Deoxyribose, a Phosphate and 1 ot 4 nitrogenous bases

The four nitrogenous bases

• Adenine

• Thymine

• Guanine

• Cytosine

Gene to protein

The proteins produced by cells determine phenotypes/

• The cells make the proteins by reading the DNA sequence and forming together amino acids to make a protein chain.

What happens when changing one base

This is a mutation, which can dramatically alter protein functions

Mutation

The premanent alteration of the nucleotide sequence of the genome

Sources of mutations

• Radiation

• Chemicals

• Viruses

Natural causes:

• Errors in DNA replication

When will a mutation pass down to its offspring

When they are present in the germ cells (gametes)

Variation

Physiological, structual, or behavioural difference between individuals within a population

Discontinous variation

• Distinct classes or categories

• They cannot be measured over a range

• Individuals cant have features that are between categories

Continuous variation

• No distinct classses or categories

• Characteristics can be measured over a range

Harmful mutation

Mutations that cause death or struggle

Neutral mutations

Mutations that have to persist in the gene pool. Don’t fo

Advantageous mutations

Mutations that help survival/ reproduction

Adaption

A characteristic that helps an organism to survive and reproduce in its enviroment. They are inhertiable

Physiological adaption

Biochemical feautre

Structural

Anatomical feature

Behavioural

activity or habit

When do variation become adaptions

The favourable variations are selected through the process of natural selection and thus become adaptions

Selective pressures

External factoes that affect an organisms ability to survive in a given enviroment.

These determine the adaptions

Industrial revolution and its impact on adaptation

• Rise of factories prompted mass migration from farms to cities.

Mimicry

• Structural adaptionwhere a harmless species resembles a harmful one

• It’s an because this a characteristic that allows for an organism to survive and reproduce better in it’s enviroment.

Darwins principle on evolution

• All living things are related

• Natural processes drive evolution

Evidence of evolution

• Comperative anatomy

• Embryology & development

• Fossil records

• DNA/ biochemical comparisons

• Biogeography

• Observation evidence

Comperative anatomy

The body parts of very differen organisms are similar. Thus showing they are related to a common ancestor

Vestigiality

The rention of structures that have lost some or all of their ancestoral function

Homologous structures

• Evolved from a common ancestor

• Similar anatomy

• Different functionality

Analogous structures

• Evolved independently

• Anatomically different

• Similar functionality

Embryology and development

• Embryonic similarties are present in non-similar verterbrate species. The more closely they are related, the more similarities they share

Fossil records

Fossils display incremental changes over time.

Older layers= simpler organisms

Mass extinction show evolutionary recssion and succession

Transitional forms

Organisms that connect distant relatives

• Archaeopteryx

• Tiktaalik

DNA comperative

• More closesly related organisms have more similar DNA

Evolutionary tree

A diagram that shows how species are related and how they branced off from shared ancestors over time

Cousins

The familial relation between two organisms that share a common ancestor

Biogeography

Closely related species are found in areas that are, or were geographically close to eachother.

Distant species with similar features under conditions with similar sleective pressures

Observations evidence

Viruses evolve in order to adapt to their host and thus cause antibiotics to not work because they are already adapted to suruve them

Natural selection

The process where organisms better adapteed to their enviroment tend to survive and produce more offspring. As the generations pass, the stronger/ desirable phenotypes persist.

Fitness

The ability of an organism to pass its genes on to its offspring and then the next generation

Sexual selection

Naturla selection happening though the preference by one sex for certain traits in individuals of the other

Gene pool

The combination of all the genes (including alleles) present in a reproducing population or species.

A larger gene pool is better to withstand unexpected enviromental challenges

Stabilizing selection

The intermediate variation converys greater fitness than the extermes

Directional selection

Variations towards one end of the spectrum have higher fitness

Disruptive slection

Variations at both extermes convey greater fitness

Genetic drift

The change in allele frequency within a population over generations due to random choice

Founder effect

A form of exterme genetic drift where genetic variation is lost when a new populatin is established by a small grouo

Genetic bottleneck

A form of exterme genetic drift in which a single event drastically reduces genetic variation

Gene flow

The transfer of genetic variation from one population to another

Speciation

The formation of one or more distinct species from a prexsisting population

Causes:

• When a group become reproductively isolated from other in the population

• After time, selective pressures will make each group evolutionarily distinct

Allopatric speciation

when biological populations of the same species become isolated due to geographical changes

Sympatric speciation

Speciation within the same habitat due to behavioural or temporal changes

Abrupt speciation

Where speciation happens in one generation, usually happens in plants.

Possible because plants can remain vaible despite being polyploid

New polyploid plants can no longer breed with parent generation due to incompatible ploidy

Polyploid

An organism with two or more sets of chromosomes

Autopolyploidy

Polyploidy resulting from the fusion of polyploid gamaetes from the species

Allopoluploidy

Polyploidy that happens because of fusion of polyploid gamaetes from close related species/ sub

Descent with modification

• Humans evolved through natural selection.This mean that traits helping with survival and reproduction become more common over generation

Sahelanthropus

• Lived 7 million years ago in central africa

• Potentially earliest human ancestor with bipedalism

Australopithecus

• Walked upright 4 million years ago, small brain

• Lucy is apart of this

Homo erectus

• First to leave Africa, use fire, and make complex tools

Homo neanderthalensis

• Came before modern humans in Europe; adapted to the cold, intelligent and interbred with us

Major steps in human evolution

• Bipedalism: Allowed to free our hands for tolls use and improving energy efficency

• Brain growth: Our brain sized tripled this allowed for complex thinking, language, and culture

• Tool use: Simple stones —> adavanced tools that helped for survival and social cooperation

• Language: Enabled knowledge sharing, planning, and cultural transmission

Modern humans

• Slender builds, high foreheads.

• Excelled in symbolic thought, art, and long distance trade

Neanderthals

• Stockier, adapted to cold climates

• Used tools to bury their dead, but generally had les symbolic expression.