lecture 11

• variation • heritable • difference in fitness • all of these can be met at the molecular level

• lower level selection can reduce the fitness of the indivisual example: cancer cells • cancer cells replicate more than normal cells so cancer cell will be favored • natural selection will favor cancer cell but its harmful for the indivisual

• if lower level units cooperate, higher level fitness can be avoided

• mitosis and meiosis mitosis: - when somatic cell divides, they are clones of each other - without variation, evolution cant happen meiosis: - when a zygote is made its 50% mom and 50% dad - both mom and dad has an equal chance of getting passed on so no one is favored • development and multicellularity (somatic cell) - every cell comes from the same zygote so no competition - if the cell starts with different information, it will create initial competition

fair meiosis - each allele has a 50% chance of getting passed on

• normally in meiosis 50% from mom and 50% dad gets passed on • if one allele cheats, it gets passed on more than 50% • could reduce the fitness of individual

• normally when a gene needs to make copies of themselves, it needs to go through meiosis or mitosis -TE can copy itself without going through mitosis or meiosis • this allows over replication and increase in number

• methylating TE - when TE are methylated, it will be wrapped in chromatin and prevent it from translation • balancing TE copy number - at the gene level, selection favors TE - at indivisual level, selection is against TE - a balance is achieved

• minimize variation at lower level • make sure genes make the indivisual succesful • selection at higher level can counteract

• starting with a single somatic cell reduces competition • mutation in somatic cells arent passed on