Adaptation and Variation

• Organisms face environmental challenges that limits their ability to survive.

Example: • severe weather• Famine• Competition for food• Competition for mates• Competition for mates

• Organisms that survive long enough to reproduce have the opportunity to pass along to their offspring the genetic information that helped them survive

• Adaptation: is a structure, behaviour or physical process that helps an organism to survive and reproduce in a particular environment

Example: Hibernation

• Hibernating species reduce their metabolism to save energy. Animals that hibernate have a better change of surviving a harsh winter than an animal that does not.

Mimicry

• Many harmless species resemble a harmful species in colouration or structure.

• Predators that avoid the harmful species will also avoid its mimic.

Viceroy butterfly is palatable Monarch butterfly tastes badly to predators

By catching and eating a monarch butterfly, predators learn to avoid both butterflies because the colouration and structure warn them of the bad taste.

Development of adaptations• Adaptations are the result of gradual,

accumulative changes that help an organism survive and reproduce

• Variations: are structural , functional, or physiological difference between individuals.

• Not all variations become adaptions• Environmental conditions determine whether a

variation in an individual has a positive, negative effect, or no effect on the individual’s ability to survive

• Helpful variation = more likely to survive• Survival = more offspring with same trait• Trait then become more common in

population

Example: English peppered moth

• Has 3 variation: • 1. greyish- white flecked with black dots• 2. black• 3. an intermediate colour

• 1848: Black colour was extremely rare as they were more easily seen by predators on the white coloured trees

• 1898: 95% of the moths were black in the city and surrounding areas. Air pollution from the city was coating the trees and making them darker so now the black moths were camouflaged on the trees

• Genetic variation: differences within a population. The more differences, the more genetic variation

• Mutations: are changes in the genetic material. If the mutation alters the DNA in the gamete (sex cell), the mutation can be passed on the succeeding generation as a new trait. Mutations can be harmful, beneficial or neutral

• Selective advantage: is a genetic advantage of one organism over its competitors

• Over time, a selective advantage causes the organism to be favoured in terms of survival and reproduction

• The faster the organism reproduces, the more quickly that trait will become prevalent in the population