What is evolution according to Darwin?
Descent with modification.
What is evolution in modern biology?
Differential reproductive success of genes within a population.
Who are the two scientists credited with developing the theory of natural selection?
Charles Darwin and Alfred Russel Wallace.
What was Darwin influenced by during his voyage on the H.M.S. Beagle?
Charles Lyell’s ‘Principles of Geology’ and the concept of uniformitarianism.
Where did Darwin make key observations that influenced his theory?
In Patagonia and the Galápagos Islands.
What did both Darwin and Wallace observe about organisms?
Organisms live only in environments to which they are well adapted; those not well adapted fail to reproduce successfully.
When was the theory of natural selection first jointly presented?
1858, to the Royal Society.
When was Darwin’s ‘On the Origin of Species’ published?
1859
List the main points of Darwin’s theory of evolution.
- Variation exists within populations. 2. Variation is heritable. 3. Some traits confer survival advantage. 4. Fittest individuals reproduce more. 5. Natural selection acts on this variation.
What provides the raw material for natural selection to act on?
Variation within a population.
What is the genetic basis of evolution?
Traits are coded by DNA, which forms genes and chromosomes; variation arises from sexual reproduction and mutation.
What is a mutation?
A random change in DNA that can create new traits; if beneficial, it spreads through natural selection.
List three types of mutations.
Deletions, duplications, and inversions.
What is natural selection?
The process where heritable traits that increase fitness become more common in a population over generations.
What does ‘survival of the fittest’ mean?
Fitness refers to the probability of successful reproduction, not necessarily strength or speed.
How does natural selection depend on the environment?
The traits that are beneficial depend on the environment; if the environment changes, so does which traits are advantageous.
Does evolution ever stop?
No, because mutation, recombination, and natural selection continue to change genetic composition over time.
How does population size affect evolution?
Large populations evolve slowly with more genetic diversity; small populations evolve faster but are prone to extinction.
What is convergent evolution?
Independent evolution of similar traits in unrelated species due to similar environmental pressures (e.g., bird and bat wings).
What is the biological species concept?
A species is a group of organisms that can interbreed and produce viable offspring.
What is the morphological species concept?
Species are distinguished by physical (morphological) differences, such as bone structure.
What is preservation bias in the fossil record?
Unequal preservation of organisms can distort our view of evolutionary patterns.
What is origination rate?
The rate at which new taxa evolve or appear in the fossil record.
What is extinction rate?
The rate at which taxa disappear through time; 99% of all species are now extinct.
