evolution unit adaptation & variation section 7.1
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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?
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