EVOLUTION UNITAdaptation & Variation

Section 7.1

What are some environmental challenges that all organisms face?

Reminder of terms

Species: a group of organisms that can interbreed in nature and produce fertile offspring (they share similar morphological and genetic characteristics)

Species diversity: the variety and abundance of species in a given area

Genetic diversity: the variety of heritable characteristics in a population of interbreeding individuals

Population: a group of individuals of the same species in a specific area

Environmental challenges that

limit a population:

severe weather

access to food - famine

competition for food

access to water - drought

number of predators

space

ability to reproduce

number of offspring

Species Diversity

Diversity is the variation within the population (genetic diversity)

helps the population survive

some species may become extinct while others survive to produce offspring

What kind of variation exists

within a species?

What kind of variation exists

within a species?

Size / weight

Colour

Patterns

Speed

Number of offspring

Birth weight

Adaptation

A structure, behaviour or physiological process that helps an organism survive and reproduce in a particular environment

What adaptations does the Polar Bear Have?

What adaptations does the Polar Bear Have?

- White Fur- Semi-hibernation- Thick layer of fat- Small ears- Webbed feet

3 Categories of Adaptations

Structure: any physical feature that helps the organism survive

Behaviour: something that an organism does... an action that helps them survive.

Physiology: a body function that helps organisms survive.

Structural

Colouring

Fat

Hair

Shape of beak

Size

Camouflage

Polar Bear Example

- black skin to absorb heat

- hollow hair acts as insulation

- fur is oily and water repellant

- webbed toes for swimming

- thick layer of blubber insulates

Camouflage

Seahorse

Gecko

FrogSnake

Stick insect

MimicryMimicry: a structural adaptation in which a harmless species resembles a harmful species in coloration or structure.

Batesian mimicry: the mimicry by a palatable species of an unpalatable species

Müllerian mimicry: when two or more poisonous species, that may or may not be closely related and share one or more common predator, have come to mimic each other's warning signals.

Behavioural

mating times

migration

nocturnal activities

Behaviour Adaptation: something that an organism does... an action that helps them survive.

Physiological

Hibernation

Tolerance to temperature / salt / chemicals

Production of venom

Physiological adaptation: a body function that helps organisms survive.

How do Adaptations Develop?

No two individuals of a species are identical

Variation exists (caused by DNA and

development)

Not all variations become adaptations

Environmental conditions determine

whether a variation in an individual as a

positive, negative or no effect at all

Individuals with a helpful variation are

more likely to survive and that variation will

become more frequent

How do Adaptations Develop?