adaptation & variation

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…)

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

Adaptations

2. Behavioural• Things that animals

do, not what they have

• Eg. Meerkats standing, bird calls, migration,

Killer hornets

Japanese honey bee adaptation

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

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

• Green & orange bug game

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’ (you freak)• 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

“Superbugs”