UNIT 3 - EVOLUTION

• 3 ½ - 4 weeks … test around Nov. 23rd • Evaluation:

– 2 Quizzes, Written Test– Ind. Study Work … working in library or on

own

Adaptation & Variation

Extinction

• To completely disappear from Earth

• Results when species either lack diversity and/or the ability to change within their environment

• Eg. Dodo bird, etc.

Adaptations

• Helps an organism survive & reproduce

• Can be structural, behavioural or a physiological process

Adaptations

1. Structural• Too many to name

– Owls (talons, eyesight); sharks (sensory organs, teeth, graceful swimmers); bats (sonar); humans (brain, bipedal, thumbs), etc.

• Includes camouflage (stick insect, octopus…)

Adaptations

• Video: Camouflage

Mimicry

• A special structural adaptation• Harmless creatures posing as harmful

species in either colour or structure• Tricks predators into believing the critter is

untasty• Eg. Viceroy butterfly, king snake

Mimics

Mimicry

• Video: Animal Imposters

Adaptations

2. Behavioural• Things that animals

do, not what they have

• Eg. Meerkats standing, bird calls, migration,

Japanese honey bee adaptation

• Video: “Hornets from hell”

Adaptations

3. Physiological• Hibernation

– Bears can overwinter when food is scarce; ground squirrels can avoid harsh winters

• Tanning• Lactic Acid

fermentation (low O2)

How do Adaptations Develop?

• Gradual, accumulative changes over generations

• Random, heritable mutations in DNA

• Variations → differences between individuals (structural or physiological)

• Not all variations become adaptations

African Cichlids

Interactions with Environment

• Very important to adaptation & variation• Climates change; floods, droughts and

famines occur• Human activities – deforestation,

agriculture change landscapes• Unimportant characteristics may

eventually become crucial for survival if things change

Saguaro cactus

• Fleshy stem holds water• Most roots < 15cm deep

but cover huge area• Can absorb 750 L of water

in a single storm• Leaves reduced to spines

to reduce transpiration rate• Spines also ↓ predation• Stomata only open at night

Variation to Adaptation

The English Peppered Moth• Light peppered colour and black• Historically black was rare – lichen on

trees in England was light coloured and moths were easy targets for birds

• Industrial Revolution killed lichen and put soot on trees; 50 years later 95% of Manchester moths were black

English Peppered Moth

Pre-industrial revolution Post-industrial revolution

Peppered Moth Applet

• Fun in 17th century England! Click here

Questions

1. Sharks have an excellent sense of smell. Is this a variation or an adaptation?

2. A black and yellow insect buzzes around you, causing you to freak out. When it lands you see that it is only a fly. What is the fly’s adaptation and explain the advantage.

3. When could genetic variation have no significant effect on a species’ survival?

Mutations

• Changes in genetic material (DNA)• New alleles = genetic variation• Eg. Your DNA has about 175 mutations

compared to your parents’ • Could be harmful or beneficial• In somatic cells → tumour• In gametic cells → may be passed on

Selective advantage

• A genetic advantage of one organism over its competitors

• Helps it to survive changing environmental conditions

• Eg. Water flea surviving in warmer water temperatures

Antibiotic Resistance

• Staphylococcus aureus (bacteria) can reproduce every 30 minutes

• Adaptation can occur very quickly• Treatment of Staph. Infections can be

inhibited by the adaptive bacteria• Populations of bacteria with the new allele

can create antibiotic resistance