evolution - L15 phenotype and genetic variation PDF

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Summary

phenotypic plasticity, trade offs and complaints, fuschia pant, genetic variation, rate of living hypothesis, evolutionary theory of death, guest lecture on phytoplankton...

Description

Evolution – 03.07.2019 Lecture 15/lecture slides 12+13 *check reading list for midterm 2 info, all of chapter 13 on test

Phenotypic plasticity -

Daphnia get pointy helmet on head when reared with predators Predator avoidance…daphnia go down where it is darker to avoid predation BUT their food is in water where the light hits Reaction norms…induvial genotypes reared in diff environments with lines between them o Lots of crossing of line = genotype by environment interactions, leads to unexpected outcomes??

Trade-offs and constraints -

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Constraint you can’t evolve everything, ex: pigs can’t grow wings bc they don’t have genetic architecture Trade-off is a type of constraint  type of genetic constraint o There’s only so much energy an organism can allocate to one thing without having to compromise another Trade-off pattern o Fecundity vs egg mass of salmon Constraints: limited ability of an organism to solve a solution in the best way o Physiological, genetic, and energetic constraints

Fuscia Plant -

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green and red fuscia flower  birds only visit green flower certain colours are more obvious to pollinators, BUT not pollinated by insects so different colours are more salient to them so why even have red flower??  provide nectar reward to birds but after certain point in time it stops producing nectar, so fuscia plant turns flower red to advertise that there is no nectar so tells birds to not go to those and expend energy bc no nectar if providing no reward then the bird wont go  so must make sure they don’t cheat the bird or else they wont get pollinated days after flower opens vs proportion of flowers (y axis) o 1 day  100% flowers are green, 50% green at day 5 o peak majority are red at day 9 o blue line = flower falls off/abscised  take a while for pollen to go down tube and fertilize egg so falling off cant happen until proper fertilization occurs o needs 8 days for pollen to fertilize!! Starts green then turns red once fertilized then drops off

Genetic variation -

More common, been around for a long time so solution doesn’t look unreasonable Ex: herbivorous beetles and their host plants o Beetles don’t have genetic make up to produce enzymes to overcome defense of other plants, become specialists for one group of plants (overcome tannins, toxicity) o Common pattern of beetles being specific to hosts

Genetic variation in population -

Mutation Gene flow Het advantage Freq dep selection Change in environment

Life History evolution -

Maturance Fecundity Body size/viability of offspring Possums o Goes through stages of life with varying dependency on mother, reaches maturity when it reproduces o Energy used for growth/mtbsm/repair up until maturity, then mtblsm/repair/reproduction once reached maturity till death

Senescence should be selected against so why do most organisms still do this? -

Pattern of aging is quite variable among species but why do all of them die?

Rate of Living Hypothesis -

Why do senesce and death evolve? Everyone has certain amount of mtblc process/cellular turnover that they are allowed 1) Mtblc rate will correspond with life span 2) can’t evolve a longer lifespan…lifespan is a constraint like pigs can’t have wings *mammalian order slide*

Telomeres  hela cells…her cells are still alive today bc cancer is immortal -

Telomeres stop working early on in birds Telomerase disfunction leads to death or whatever Telomere length and life span  species w long telomeres have really short life span o Due to cancer o If u have strong acting telomerase this will make cancer cells “go nuts”

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Precancerous cells replicate fast and if telomerase not working as fast then cells die and you get cancer???? Long lived species have to have really short telomeres or they will get killed by cell cycle regulation breakdown or cancer Within species long telomeres mean longer life BUT between species this s not how it evolved (longer telomeres mean u die faster)

Evolutionary theory of senescence and death -

Trade-off, the longer you live the more damage you have As you age you allocate energy to reproduction rathe than repair Fig 13.10a At age 0 there is 100% alive, 20% die each year Inbreeding depresh of fruit fly slide  using energy not to keep repair going but to reproduce, inbreeding depresh inc with age Reproductive success increased simply by moving one year earlier and killing off everyone after age 9 (6 years taken off lifespan)

GUEST LECTURE – Phytoplankton

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Phytoplankton found in photic zone of water  closest to water surface, receives mot sunlight Found in various environments (diff temp, location, lights levels, nutrient levels) Species differ from one body of water to another (fresh, braker, salt) Diff pops have come to evolve and survive successfully in their own environments Adapt to local environuts (local adaptation) Why are they important? o 1. Base of the food chains o 2. Key regulators of atmospheric CO2 o 3. Responsible for half of words primary production Research objectives o Explore spatial and temporal influence of phytoplankton diversity o Test resilience of phytoplankton Phytoplankton and climate change o Need phytoplankton for healthy aquatic environment o Atmospheric CO2 inc  leads to dec in pH  ocean acidification o Light availability and water temps are increasing Adaption and phenotypic plasticity o Must adapt to the trends 24 water samples collected across NA (8 fresh water, 8 marine, 8 brackish) DNA extracted from all samples, amplified with PCR, then sequenced Same species = 97% shared sequence Phytoplankton resilience to UV radiation

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o Evolved natural resistance to UV radiation Ballast water stabilizes ship during transit, takes on water from surrounding area which includes organisms Phytoplankton can cause harmful algal blooms that release toxins that poison wildlife and contaminate seafood Ballast water must be treated before release, usu use UV radiation but effects of this are unknown on phytoplankton UV can mess up lipids, proteins, DNA Water samples collected, exposed to UV, rest in dark, exposed to UV again  do this to see if DNa is being damaged Damage seen through gene expression  damage to photosynthesis, UV repair, DNA replication Used next generation sequencing Phytoplankton have adapted and evolved to survive in various environments, evolved resistance to UV radiation...