AP Biology Evolution of Populations Doonesbury - Sunday February 8, 2004 AP Biology Populations evolve ▪ Natural selection acts on individuals ◆ differential survival ▪ “survival of the fittest” ◆ differential reproductive success ▪ who bears more offspring ▪ Populations evolve ◆ genetic makeup of population changes over time ◆ favorable traits (greater fitness) become more common Presence of lactate dehydrogenase Mummichog AP Biology Changes in populations Bent Grass on toxic mine site Pocket Mice in desert lava flows Pesticide molecule Insect cell membrane Target site Resistant target site Insecticide resistance Target site Decreased number of target sites
8
Embed
Populations evolve - Springfield Public Schools · errors in mitosis & meiosis environmental damage Sex mixing of alleles recombination of alleles •new arrangements in every offspring
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
AP Biology
Evolution of Populations
Doonesbury - Sunday February 8, 2004
AP Biology
Populations evolve▪ Natural selection acts on individuals
◆ differential survival▪ “survival of the fittest”
◆ differential reproductive success▪ who bears more offspring
▪ Populations evolve◆ genetic makeup of
population changes over time
◆ favorable traits (greater fitness) become more common
Presence of lactate dehydrogenase
Mummichog
AP Biology
Changes in populationsBent Grass on toxic mine site Pocket Mice in desert lava flows
Pesticidemolecule
Insect cellmembrane
Target site
Resistanttarget site
Insecticide resistance
Target site
Decreased number of target sites
AP Biology
Individuals DON’T evolve…Individuals survive or don’t survive…Populations evolve
Individuals are selectedIndividuals reproduce or don’t…
AP Biology
Fitness▪ Survival & Reproductive
success◆ individuals with one
phenotype leave more surviving offspring
Body size & egg laying in water striders
AP Biology
Variation & natural selection ▪ Variation is the raw material for natural
selection◆ there have to be differences within population◆ some individuals must be more fit than others
AP Biology
Mean beak depth of parents (mm)
Medium ground finch88 9 10 11
9
10
11
1977 1980 1982 1984
Dry yearDry year
Dry year
Wet year
Bea
k de
pth
Bea
k de
pth
ofof
fspr
ing
(mm
)
Where does Variation come from?▪ Mutation
◆ random changes to DNA▪ errors in mitosis & meiosis▪ environmental damage
▪ Sex ◆ mixing of alleles
▪ recombination of alleles• new arrangements in every offspring
▪ new combinations = new phenotypes◆ spreads variation