BLG 144 Lecture Notes - Lecture 3: Gene-Centered View Of Evolution, Acclimatization, Allele Frequency

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27 Apr 2018
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The Nature of Natural Selection and Adaptation
- Idiiduals do’t hage, the etire populatio does
- Acclimation and acclimatization are not examples of examples
- These our he the idiiduals’ pheotpe hages i respose to hages i the
eiroet ut the geotpe reais fied so it does’t pass it o to the offsprig.
sie it does’t pass it o, its ot adaptig
- Acclimation Physiological adaptations that occur through experimentally induced
stressors
- Acclimatization - Physiological adaptations that occur from natural environmental
stressors (artic fox white in winter, and brown in the summer)
Selection acts on individuals, but evolutionary change occurs in populations
- Aliatizig happes to idiiduals i a eiroet, ut this is’t a geeti hage.
- Over time, population changes genetically when its allele frequencies change
- Whe alleles for a trait are est suited to surie, it’ll e ore frequent in the next generation
Eolutio is’t progressie
- Helps species become better adapted to local conditions
- Since it survives more, it will reproduce its offspring more than others not suited to that
environment
- It can drive evolution toward reduced complexity, not increased( eg. Tapeworm)
Selfish gene versus the Selfish individual
- No higher or lower organism. Each adapts to its own environment
- orgaiss do’t at for the good of speies. Bad gees a also get passed do. Eg. Leigs
do’t suiide when their population gets too high
- A idiidual does’t ake a eat op of itself hereas a gee a.
- Gene is a replicating unit, whereas the individual is the vehicle for gene replication
- Individuals can act to maximize their own fitness, other ways of maximizing transmission of its
o ersios of a gee ithout aiizig its o reprodutio. eg. Ki seletio Lios
pride) and altruism ( vampire bats sharing blood meals)
Limitations of Natural Selection
- Non-adaptive Traits
- Adaptations of organisms are limited by genetic constraints, fitness trade offs, and
historical constraints
- Genetic constraints - when selection, favoring an allele for one trait, causes a
connection but a weakened change in another trait associated with the allele ( eg. Bird
needs larger beaks to eat bigger seeds but it makes the beaks more weaker so it breaks)
happen because of pleiotropy(single cell affects multiple traits) lack of genetic variation
also constrains evolution
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Document Summary

Acclimation and acclimatization are not examples of examples. These o(cid:272)(cid:272)ur (cid:449)he(cid:374) the i(cid:374)di(cid:448)iduals" phe(cid:374)ot(cid:455)pe (cid:272)ha(cid:374)ges i(cid:374) respo(cid:374)se to (cid:272)ha(cid:374)ges i(cid:374) the e(cid:374)(cid:448)iro(cid:374)(cid:373)e(cid:374)t (cid:271)ut the ge(cid:374)ot(cid:455)pe re(cid:373)ai(cid:374)s fi(cid:454)ed so it does(cid:374)"t pass it o(cid:374) to the offspri(cid:374)g. (cid:894)si(cid:374)(cid:272)e it does(cid:374)"t pass it o(cid:374), its (cid:374)ot adapti(cid:374)g(cid:895) Acclimation physiological adaptations that occur through experimentally induced stressors. Acclimatization - physiological adaptations that occur from natural environmental stressors (artic fox white in winter, and brown in the summer) Selection acts on individuals, but evolutionary change occurs in populations. A(cid:272)(cid:272)li(cid:373)atizi(cid:374)g happe(cid:374)s to i(cid:374)di(cid:448)iduals i(cid:374) a(cid:374) e(cid:374)(cid:448)iro(cid:374)(cid:373)e(cid:374)t, (cid:271)ut this is(cid:374)"t a ge(cid:374)eti(cid:272) (cid:272)ha(cid:374)ge. Over time, population changes genetically when its allele frequencies change. Whe(cid:374) alleles for a trait are (cid:271)est suited to sur(cid:448)i(cid:448)e, it"ll (cid:271)e (cid:373)ore frequent in the next generation. Helps species become better adapted to local conditions. Since it survives more, it will reproduce its offspring more than others not suited to that environment.

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