10.8 Changing Population Characteristics

Question 1

What is a selection pressure?

Answer 1

A factor that affects an organism’s chances of survival or reproductive success.

Question 2

Give examples of selection pressures.

Answer 2

Predation, competition (for mates and food), disease

Question 3

State the process of natural selection.

Answer 3

1- Organisms within a species show variation in their characteristics due to genetic variation
2- Organisms who are best adapted to a selection pressure due to an adaptation have an increased chance of surviving and successfully reproducing. Less well-adapted organisms die or fail to reproduce
3- Successful organisms pass the allele encoding the advantageous characteristic onto their offspring
4- This process is repeated for each generation, with the proportion of the population with thet advantageous gene increasing
5- Over long periods of time, this leads to evolution

Question 4

State examples of evolution.

Answer 4

-MRSA have evolved, developing resistance to many antibiotics
-Peppered moths evolved to be darker coloured after the industrial revolution darkened the colour of tree bark.