Download
1 / 22
250 likes | 577 Views
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
E N D
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 • 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
Adaptations • Behavioural • Things that animals do, not what they have • Eg. Meerkats standing, bird calls, migration,
Adaptations • 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
Questions • Sharks have an excellent sense of smell. Is this a variation or an adaptation? • 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. • 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
