unit 3 - evolution
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UNIT 3 - EVOLUTION. 3 ½ - 4 weeks … test around Nov. 23 rd Evaluation: 2 Quizzes, Written Test Ind. Study Work … working in library or on own. Adaptation & Variation. Extinction. To completely disappear from Earth - PowerPoint PPT PresentationTRANSCRIPT
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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
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Adaptation & Variation
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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.
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Adaptations• Helps an organism
survive & reproduce• Can be structural,
behavioural or a physiological process
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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…)
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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
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Mimics
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Adaptations
2. Behavioural• Things that animals
do, not what they have
• Eg. Meerkats standing, bird calls, migration,
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Japanese honey bee adaptation
• Video: “Hornets from hell”
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Adaptations
3. Physiological• Hibernation
– Bears can overwinter when food is scarce; ground squirrels can avoid harsh winters
• Tanning• Lactic Acid
fermentation (low O2)
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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
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African Cichlids
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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
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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
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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
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English Peppered Moth
Pre-industrial revolution Post-industrial revolution
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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?
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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
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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
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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