Evolution by Natural Selection Flashcards
Who developed the theory of evolution by natural selection?
Charles Darwin in 1859
What did Darwin make?
Key observations about the world around him
What was Darwin’s first observation?
Noticed organisms produce more offspring than survive
What was Darwin’s second observation?
There is variation in characteristics between members of the same species
What was Darwin’s third observation?
Some of these characteristics can be passed on from one generation to next
What was Darwin’s fourth observation?
Individuals best adapted to their environment are more likely to survive
Why did Darwin write his theory?
To explain his ideas
What was the first element of his theory?
Individuals within a population show variation in their phenotype
What was the second element of his theory?
Selection pressures create a struggle for survival
What are examples of selection pressures?
Predation, competition etc
What was the third element of his theory?
Individuals with better adaptation are more likely to survive and reproduce
What was the fourth element of his theory?
Adaptations passed onto offspring
What was the fifth element of his theory?
Over time, the proportion of the population possessing the advantages adaptation increases
What was the sixth element of his theory?
Over generations, this leads to evolution as the advantageous adaptations become more common
Based from his theory, what do we now know about certain individuals?
That they show variation in phenotypes as a result of genetic variation (different alleles)
What happens to advantageous alleles?
Passed onto offspring
Who if Alfred Russell Wallace?
He worked at the same time as Darwin and played an important role in the development in the theory of natural selection
What did Wallace come up with?
Independently came up with the idea and wrote to Darwin about it
What did Wallace and Darwin do together?
Published their papers on evolution and acknowledged each others work although they disagreed on the mechanisms (the way it works)
What did Wallace’s observations provide?
Evidence to support the theory
What did Wallace realise which provided the evidence to support his theory?
That warning colour used to deter predators was an example of advantageous adaptation that had evolved by natural selection
When did other scientist start to pay attention to Darwin and Wallace’s ideas?
When Darwin published his book ‘On the Origin Species’
What is covered in the book and why is it memorable?
He gave evidence to support the theory and is why he is better remembered than Wallace
What are the 3 pieces of evidence for evolution?
-Fossil Record
-DNA
-Molecular
What are fossils?
Remains of organisms preserved in rocks
What is the fossil record evidence for evolution?
By arranging fossils in chronological order, we can observe gradual changes in organisms
What is the DNA evidence for evolution?
-Theory of evolution suggests that all organisms evolve from a common ancestor
-Closely related species diverged more recently
What happens to organisms DNA that have diverged more recently?
Have more similar DNA as less has passed for base sequence to change
What is evolution caused by?
Gradual changes in base sequence of DNA
What happens in eukaryotes with DNA evidence?
DNA is found in a nucleus but there is also DNA in mitochondria and we can look at the differences in mitochondrial DNA
What is the molecular evidence for evolution?
We can compare the sequence of amino acids in proteins and compare antibodies
What happens to organisms that have diverged more recently in relation to molecular evidence?
Have more similar molecules as less time has passed for changes to proteins to occur
What is Phylogeny?
Is the name given to the evolutionary relationships between species
What is a Phylogenetic Tree?
A diagram that represents the lines of evolutionary descent of different species, organisms, or genes from a common ancestor
Draw and Label an example of a Phylogenetic Tree.
See Notes
What is the first advantage of using Phylogenetics?
Classification uses knowledge of phylogeny in order to confirm the classification groups are correct of causes them to be changed
What is the second advantage of using Phylogenetics?
Is a continuous tree where as classification requires discreet groups into which some organisms might not quite fit
Why is the hierarchical nature of linean classification misleading?
As it implies different groups within the same rank are equivalent
