B5.2 Natural Selection And Evolution Flashcards
Non-coding DNA
Regions of DNA which do not encode protein sequences
Cystic fibrosis
Caused by a mutation in a region of coding DNA
Extra mucus is produced in the body
Evidence fossils provide
History of past life on earth
Why fossils are a significant source of evidence
Show evolution within a species and evolution between one group of organisms
Can help to build a comprehensive history
Allow a picture to be built in terms of life upon Earth e.g. earliest fossils bacteria, then plants, then animal fossils
How fossil evidence shows evolution has occurred
Systematic change through time
Different fossils found in different rock
Oldest layers of rock show oldest fossils
What can be seen in the fossil record
Increase in complexity over time, simple organisms appeared first
Increase in diversity
Intermediate forms between groups - transitional fossils
What can not be seen in the fossil record
Unable to show how life started on earth
Earliest fossils were soft bodied - difficult to fossilise
Does evidence from fossils provide conclusive proof of change
No
Record is biased/incomplete
Very few individuals become fossils
Hard-bodied organisms often form fossils
Most fossils are aquatic animals
Main fossil types found
Impressions - when footprints become covered in mud which hardens to rock
Moulds - when a dead organism gets buried in mud, which hardens to rock
Caste fossil - when mould fossils are filled with minerals that harden, taking the shape of the mould fossil
Preserved fossil - when animals have been covered in a natural preservative such as ice, tar, amber or peat
How extinction provides evidence for evolution by natural selection
Species which are not adapted to / do not have advantageous characteristics for their environment die out
Fossil
Remains of a plant or animal which have mineralised / changed to rock over millions of years
Most likely ancestor of all living things
Unicellular aquatic organisms
How organisms evovle
Process of natural selection
Process of evolution by natural selection
Genetic variation within species caused by differences in genes
Organisms which have the most advantageous characteristics are the most likely to survive and reproduce
Genes from successful organisms are passed to offspring
Process is repeated many times and can lead to new species developing
Survival of the fittest
Only organisms which have most advantageous characteristics are the most likely to survive and reproduce
Why must scientist constantly develop new antibiotics
Bacteria reproduce quickly,
so any mutation which develops antibiotic resistance is quickly passed on to many offspring
Examples of evolution that has happened in a short and observable time period
Peppered moth changing from pale to dark due to industrial revolution
Bacteria evolving resistance to antibiotics
Mosquitos evolving resistance to DDT
Rats evolving resistance to the rat poison warfarin
During Darwin’s scientific expedition to the Galapagos Island, on which species did he make his famous observations
Finches
He wrote the book “The origin of species”
Charles Lyell’s hypothesis about the origins of fossils
Gave Darwin inspiration for theory of evolution by natural selection
The theory of spontaneous generation
Animals are produced from their surroundings or environment
e.g. sudden appearance of fish in a puddle of water
Key ideas of Jean-Baptiste Lamarck
All organisms evolved through simple to more complex organisms
Use vs. Disuse
Organisms adapt during their lifetime - altered their behaviour in response to environmental change, which modifies their organs
Acquired traits are heritable - when giraffes stretch their necks to reach leaves high in trees, they would strengthen and gradually lengthen their necks. These giraffes would then have offspring with slightly longer necks
Continuous evolution towards ‘perfection’ - If an organism has to repent the same task everyday, their body would adapt for it to increase efficiency
Alfred Wallace (1809-1882)
Independently proposed the theory of evolution by natural selection while working in Borneo
Key ideas:
Living things change over long periods of time
Fittest individuals survived and reproduced
Advantageous characteristics passed on to their offspring
Speciation by reproductive isolation – Wallace effect
Studied Beetles and butterflies
Why did theory of evolution take time to be widely accepted
At the time of publication, most people believed God created all animals and plants
Darwin’s opposed this belief
Darwin was unable to explain how inheritance occurred
Darwin had no knowledge of genes, which meant it was hard to convince people that the theory was correct
It took time to collect further evidence to support the theory
3 key scientists who provided evidence for the theory of evolution
Charles Lyell
Charles Darwin
Alfred Wallace
(Lamarck)
Classification
Grouping of organisms into groups based on similarities and differences between them
Linnaean classification system
Classification is the organisation of living things into groups according to their similarities in structure and characteristics
Closely related organisms are grouped together into groups called ‘taxa’:
Each taxa is arranged in a hierarchy, which divide into smaller more specific taxa
7 levels of the kingdom:
Kingdom - Phylum - Class - Order - Family - Genus - Species
Kittens Prodded Croupiers Once Freud Glided Shamefacedly
Phylogeny and how has it advanced classification
Study of evolutionary relationships with the aid of modern techniques such as DNA and protein analysis
- Has led to the re-classification of some organisms
- Has led to devlopment of the 3-domain system and the new taxon ‘domain’
3-domain system
Proposed by Carl Woese
Classifies based upon chemical analysis - DNA, RNA and protein comparison to show phylogenic links
Three domains:
Eukaryota – organism with complex subcellular structures (animals, plants, fungi, protist)
Bacteria – true bacteria
Archaea – primitive bacteria
Artificial classification
Grouping by observable characteristics not phylogeny
Method led to inaccurate classification
Linnaeus’s method of classifying plants based on a limited number of their physical and sexual characteristics
Speciation
When organisms evolve to become distinct species
Fertile offspring cannot be produced among the distinct species
Extinction
When there are no remaining individuals of a species alive
