Bio 201 F09 True lect 3 (L3)v3r

Bio 201 F09 True lect 3 (L3)v3r - Todaysfactoid :on...

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Today’s factoid World Animal Health Organiza:on found in a recent study that climate change is likely to be promo:ng the spread of many animal diseases, including may that are dangerous to humans blue tongue virus (sheep; spread by midges) West Nile virus (birds, animals; spread by mosquitos) mechanisms include weather changes aFec:ng distribu:ons of flying insects ‘Climate Change and Animal Disease’ posted on Biology in the News in BB http://lib.sytu.edu.cn/ASM/048-7.jpg
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business • introduc:ons • Echo video system is now working, including audio – watch the BB page for links to the lecture videos – these are only for use by Bio 201 students • unauthorized reproduc:on not permissible • weekly ques:ons – posted on BB aRer Friday lecture each week – see TAs during office hours for answers
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Important to remember: Selection does not produce mutations, it favors some randomly produced mutations and disfavors others. (=Natural Selec&on)
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Antibiotic- resistant cells selected in an antibiotic-rich environment Antibiotic treatment Rapid Selec+on Purple cell has a mutation conferring resistance: pre- existing variation, Initially not detectable . Bacterial population
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• It is oRen hard to conceive how such complexity evolved in a gradual or stepwise manner. • Each step must be adap:ve, or at least not disadvantageous – some traits may be “neutral” – we will see in a future lecture that a great deal of DNA sequence varia:on is thought to be neutral
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Retina (photoreceptor cells) Cornea (lens)
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Evolu:on of eyes Some eyes are complex, some are simpler SpeciFc eye types (cell and :ssue conFgura:ons) evolved independently Photoreceptor cells May have evolved just once The Frst eyes ‐ probably just a few photorecep:ve cells, like planarian worms Photorecep:ve pigments (opsins) in these cells
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Bio 201 F09 True lect 3 (L3)v3r - Todaysfactoid :on...

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