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Process of Evolution by Natural selection, mechanism of evolution - Coggle…
Process of Evolution by Natural selection
Evolution by Natural selection
Evolution
Evolution is a change in the heritable traits over time
All species shared a common ancestor
Is driven by changing the phenotype and genotype of population
Natural selection
Variation
Variation is a difference in traits in population
Necessary for species to evolve
Caused by small changed within the DNA called mutations resulting in new traits
Can be as a result of something harmful in environment
Mutations can be harmful, have no effect or be beneficial resulting in an advantageous trait
Selection pressures
A challenge that affects an organism’s ability to survive in the wild
Examples
Predators
Disease
Climate
Access to resources
Human activities
Drive for natural selection
those better adapted will survive and the lesser will die out
Traits
Phenotype
Observable characteristics of an individual resulting from the expression of genes eg: hair colour, eye colour
Genotype
The genetic make up of an organism
A trait is any feature of an organism
Acquired
Gained by an organism during lifetime
Genetic
A feature that can be passed down
Trade-Off
gaining a survival advantage but having a negative
eg: different colour for camouflage but less attractive to mates
the survival and reproduction of the individuals who are better adapted to their environment
First proposed by Charles Darwin in the 1800s, he argued that it created genetic diversity and all life forms evolved from a common ancestor
Changes genetic composition of entire populations
Natural selection importance on populations
Advantageous and Disadvantageous Traits
Advantageous traits are traits that are more likely to make an organism survive and reproduce (Adaptation)
Likely to have more offspring often inheriting parents traits causing an increase in frequency of the trait in the population
Disadvantageous traits are traits that are less likely to help an organism survive and reproduce
Organisms with disadvantageous traits will decrease in frequency and eventually die out
Leaving a more adapted population
Examples
A trait that helps an organism increase access to resources
Less likely to mate
Genetic variation and Diversity
Genetic variation alters protein function giving rise to a new trait
Over time, as generations of individuals with the trait become more frequent, the population is different from the ancestral one
Differences introduced by variants may help an organism survive in one setting but not in another
Speciation
new kind of plant or animal species is created
How it happens?
Occurs when a group within a species separates from other members of its species and develops its own unique characteristics
a different environment or characteristics of members of the new group will differentiate the new species
Example: Galapogas Island Finches and beak shape
Types of speciation
Allopatric-Isolation between 2 groups and different selection pressures
Peripatric- Small groups break off forming a new species
Parapatric- spread out over large area
Artificial- Creation of new species by humans
Fitness
how well organisms survive and reproduce (how many offspring an organism with a specific phenotype or genotype leaves in the next generation
Depends on ability to attract a mate and number of offspring produced per mate
Adapted to Environment
NS keeps population consistently adapted to population over time
Key features of evolution by natural selection
Sexual Selection
Another theory proposed by Charles Darwin
Competition between individuals of the same sex for breeding partners
Often competition between males for females
Example: Female Peacocks are more likely to reproduce with brighter coloured male peacocks resulting over time in a brighter male population
Steps of Natural Selection
Variation
Organisms can vary in size, colouration, ability to fight diseases and other traits
Occurs during cell division by random changes to the DNA called mutations
Heritable and can be passed onto offspring
Adaptation
Variation may allow for traits to be beneficial to the organisms survival or reproduction
Traits that give a population a survival advantage in their environment
Types of Adaptation
Structural
Change in Organism's body eg thicker fur
Behavioural
Changes in Organism's Behaviour eg: seeking shade in the hot climate
Physiological
internal body processes eg: during hibernation bears slow down digestive processes
Survival
Populations have way more offspring than resources available
Competition for resources in environment
Those with favourable traits and adaptations will be more likely to survive and thrive
Reproduction
Those with variation and better adapted are more likely to survive and reproduce
When organisms reproduce they pass DNA to their offspring, traits are contained within small sequences of DNA called genes
Offspring often inherit their traits from parents
Population Changes over time
Organisms that are better adapted to survive and reproduce will continue passing on traits to offspring
Resulting in an increase of frequency of the trait
Showing natural selection and a better adapted population
mechanism of evolution