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Understanding Evolution: Adaptation and Variation in Species

This educational overview covers key concepts of evolution, including adaptation, variation, and extinction. Through quizzes and a written test, students will explore how species adapt to their environments and the consequences of lacking diversity. Real-world examples, such as the adaptations of the Dodo bird, owls, and the English peppered moth, will illustrate vital processes in natural selection. The impact of human activities on species survival and the rapid adaptation in bacteria, like antibiotic resistance, will also be addressed.

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Understanding Evolution: Adaptation and Variation in Species

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  1. 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

  2. Adaptation & Variation

  3. 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.

  4. Adaptations • Helps an organism survive & reproduce • Can be structural, behavioural or a physiological process

  5. 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…)

  6. Adaptations • Video: Camouflage

  7. 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

  8. Mimics

  9. Mimicry • Video: Animal Imposters

  10. Adaptations • Behavioural • Things that animals do, not what they have • Eg. Meerkats standing, bird calls, migration,

  11. Japanese honey bee adaptation • Video: “Hornets from hell”

  12. Adaptations • Physiological • Hibernation • Bears can overwinter when food is scarce; ground squirrels can avoid harsh winters • Tanning • Lactic Acid fermentation (low O2)

  13. 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

  14. African Cichlids

  15. 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

  16. 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

  17. 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

  18. English Peppered Moth Pre-industrial revolution Post-industrial revolution

  19. Peppered Moth Applet • Fun in 17th century England! Click here

  20. 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?

  21. 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

  22. 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

  23. 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

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