7.3 Natural Selection Flashcards
Why does natural selection work?
Because the fittest organisms survive to breed
Why do some animals produce so many offspring?
Because a huge number are lost to predators, starvation, lack of shelter etc.
How many offspring (children, grandchildren and great grandchildren) wcan a pair of rabbits produce in one breading season?
800
What do all the organisms in a population compete for 3
Food,
shelter (from the environment and predators)
Mates
What kind of characteristics make it more likely that an animal will survive to breed
The best camouflage,
The best eyesight,
The best runner
The best digger
Note - what is important to the survival of an animal depends on what species it is, eg eyesight not important to moles.
What is it called when a gene changes accidentally to become a new form of the gene?
A mutation
Are mutations of genes good or bad?
Can be either, it depend on whether the mutation makes it more or less likely that the organism will survive to breed.
How can mutation be important in natural selection?
If animals with a mutated gene are more likely to survive than those without the gene they will pass this on to their offspring
Give an example of an animal that benefited from a mutated gene
When myxomatosis killed most of the rabbits in the UK, a few had a mutated gene which gave them immunity. Those with the mutated gene survived to breed.
