Evolution Flashcards
What is the consequence of evolution?
Biodiversity
How can biodiversity be described?
Species diversity and genetic diversity
What is species diversity?
Number of different species within an ecosystem
What is genetic diversity?
Range of genetic characteristics within a single species
How can genetic variation occur?
Variation in offspring and mutations
What is when there is a variation in offspring?
When genetic material from both parents combine and the offspring have genes of a random mix.
What is when there is a mutation?
When there’s an incorrect code within the gene, thus coding for something different
What is the Lamarckian theory of evolution?
- Theory of acquired characteristics
- Organisms can develop characteristics during its lifetime in order to adapt to its environment
- Those characteristics will be passed onto its offspring
- E.g. giraffes have stretched their necks to reach their food. This trait has been passed through several generations resulting in the giraffes today with long necks
What is Darwin’s and Wallace’s theory of evolution?
- Natural selection
- All organism come from a common ancestor and over time they begin to change and diverge away from this ancestor
What are Darwin’s finches?
-Exemplary example of Darwin’s theory of natural selection
-Found on Galapagos Islands
-There were 13 finches in total with different characteristics representing a different species
Cute beak: only ate fruits and seeds from trees or on the ground
Mid beak: Ate both fruits and larger insects on trees or the surface
Long beak: Ate insects within the soil e.g. worms
What are Darwin’s tortoises?
-Two types of tortoises: dry island tortoises and dense vegetation tortoises
-Hence both tortoise’s shells differ representing a new species
Dry land island where vegetation are shrubs and small trees: Shells has a higher border to allow for head mobility to access food
Dense vegetation island: Shell has lower border because there is no need for head mobility and is tougher to push through its habitat
What is Wallace known for?
- Discovery of the Wallace line
- Imaginary line dividing the fauna of Australia and Asia
- Where there was drastic difference between organism on either side of the line
- There is nothing close to a kangaroo in Asia
What are the 4 steps of natural selection?
1.Variation in a population
-Due to genetic differences from mutations and random reproduction
2.Selective pressures e.g. predation, environment
-Change in environment
-Drives evolution
E.g. Prior to Ice Age, Species of mammoth had no fur
In the population, variation occurred, few mammoths grew fur
During the Ice Age, weather changed (selective pressure) and those without fur could not survive
Those with fur survived and passed on their favourable trait to offspring
3.Individuals with favourable characteristics will survive and pass their trait to their offspring
4.Over many generations, majority of population now has the favourable characteristic
What are examples of biotic selective pressures?
Predators, access to food
What are examples of abiotic selective pressures?
- Weather
- Soil
- Habitat
Case study: The peppered moth evolution
Before the Industrial Revolution: variation of English peppered moths: black moths and white moths
Selective pressure: Industrial Revolution
- Increased production of CO2, CO and C in the atmosphere
- Carbon/ soot pollute trees and stain them black
- Black moths camouflage whilst white moths stood out
- Black moths avoided predation and passed down their characteristics
- Eventually the population of peppered moths become black
How is evolution phyletic?
The process of forming a new species is a slow, gradual and uniform