evo bio exam 4. dr. blake slu

life history

Traits that affect an organism's schedule of reproduction and survival.

reproductive strategies

Behaviors or behavioral complexes that have been favored by natural selection to increase individual reproductive success. The behaviors need not be deliberate, and they often vary considerably between males and females.

selparous, iteraparous, "crazy"

semelparity

Reproduction in which an organism produces all of its offspring in a single event; also known as big-bang reproduction.

ex) female north pacific giant octopus lives for 3-5 years reproduces once then dies

iteroparity

Reproduction in which adults produce offspring over many years; also known as repeated reproduction.

ex) giant sequoia which reproduces annually

crazy reproductive organisms

ex) kiwi which reproduces with the giant egg

Demograohy

Scientific study of population change overtime

births, deaths, immigration, emigration

lifetable

demographic tool

survivorship curve

Graph showing the number of survivors in different age groups for a particular species.

life history trade offs

some organisms: focus on growth and metabolism with little emphasis on reproduction, trying to maximize their own survival

some organisms: minimize efforts for growth and metabolism and try to maximize their reproduction rates,,

essentially the two disperse their lifetime energy differently

life history traits

Traits that affect an organism's schedule of reproduction and survival and growth

life history strategies

patterns of reproduction, growth, and survival based on trade-offs in the allocation of energy

life history trade off in the finissish

taller women= less reproduction

environmental constraints influence...

allocation of resources

crickets and life history trade offs

short winged females always allocate more energy to reproduction

longwinged females always put more energy into flight than reproduction

when food is scarce both put less energy into reproduction

K-related species

species possess relatively stable populations and tend to produce relatively low numbers of offspring

r-related species

a species that has a high intrinsic growth rate, which often leads to population overshoots and die-offs

life history traits are _______ traits

quantitative

genotypic variation can cause....

dramatic difference in phenotypic development involved in demographics

birth rate, rate of maturation, body size, survival etc,

life history trait

Heritability

the statistic that estimates how much variation in a phenotypic trait in a population is due to genetic variation among individuals in the population

phenotypic plasticity

variation in phenotypes caused by interactions between genotype and environmental factors

life history traits are influenced by:

many genes, each with small effects on development and physiology and their expression is strongly impacted by the environment

life history traits are intimately related to:

physiology,

genotype+ environmental interactions= phenotype and performance= physiological fitness

individual success determines population life table properties and the population influences the environment

these interactions lead to differing evolutioanry responses in the environment

life history traits offer opportunites for trade offs in what?

energy use.

ex)

size at birth

growth pattern

age aand size at maturity

number, size and sex ratio of offspring

age and size specific reproductive investments

age and size specific mortality schedules

length of life

aging reduces

fitness

rate of living theory of aging

aging is caused by the accumulation of irreparable damage to cells and tissues from replication and metabolism

repair effectivenes has reached its biological limit

aging is a function of metabolic rate

predictions of this theory:

1. aging rate should be correlated to metabolic rate among organisms

2. species should not evolve longer lifespans because selection for longevity is maxed out

Prediction 1 of Rate-of Living Theory and its flaw

aging rate should be correlated to metabolic rate among organisms

according to this prediction all organisms should expend about the same amount of energy per unit mass in their lifetime... but they done

prediction 2 of rate of living theory and its flaw

2. species should not evolve longer lifespans because selection for longevity is maxed out

species can actually select for longer lifespans

validity of rate of living theory of aging

-no strong support but there is intirinsic support for the physiological limit on cells

- telomeres protect the ends of chromosomes and every cell division they get shorter, unless telomerase is present

telomere length and longevity

telomere length decreases overtime

when telomeres become too short tumor suppressor protein p53 a tf production is initated that triggers a non dividing state in cells (cell senescence)

telomere lenth is inversely correlated to lifespan, short telomere reduce cell divisions but also reduce cancer risk

High levels of p53

reduce the ability of stem cells to divide and maintain and replace body parts and decrease cancer risk

mutation accumulation hypothesis

The hypothesis that senescence occurs because natural selection is not strong enough to purge deleterious mutations associated with traits that are expressed only late in life

late acting deleterious mutations are weakly selected

antagonistic pleiotropy hypothesis

the hypothesis that senescence is largely due to the evolutionary accumulation of antagonistic pleiotropic alleles that increase survival or reproduction early in life at the cost of deleterious effects late in life

pleiotropy

The ability of a single gene to have multiple effects.

reproductive effort and life history

natural selection will favor the clutch size that produces the most surviving offspring

given: future performance of parents

and reproductive success of offspring

so in some regards a slightly smaller clutch might be better

ex)more eggs this year means lower clutch next year

also offspring size

how big should offspring be

moderate?

why would a 300kg tortoise drag itself up and down a volcano every year?

tortoises follow vegetative productivity

smaller tortoise just does okay wherever so less likely to migrate bc only needs so much food and cant thermoregulate as well as big ones

migratory tortoises are in better condition and have more eggs than sedentary tortoises

bioenergetics

the study of how energy flows through living organisms

Microevolution

evolutionary change within a species or small group of organisms, especially over a short period.

change in allele frequency, occurring in humans

dynamic process which changes overtime, selection acts on individuals, but populationsa re what evolve

evolution and human health

microevo is occurring

disease is an important selective agent

GWAS helps identify allele frequency changes

pathogens and their hosts are evolved in our evolutionary arms race

Darwin's Four Postulates

1. Variation exists among individual organisms that make up a population

2. Some of the trait differences are heritable

3. Survival and reproductive success is highly variable

4. The subset of individuals that survive best and produce the most offspring is not a random sample

these are testable to see if microevolution is occurring in humans

what can lead to microevolutoin

mutation

drift

gene flow

natural selection

artificial selection

disease is a _____ agent

important selective

different pathogens impose

-different selective pressures

pathogencity

ability to infect a host and cause disease

aggressiveness (of a pathogen)

the ability of the pathogen to invade and establish within the host

virulence (of a pathogen)

severity of disease

Why did leprosy decline?

The leprosy pathogen is very similar to the one that causes tuberculosis. If a person has Tb they are immune to leprosy. As cities grew and Tb spread with increased crowding, population immunity to leprosy likely increased. Also, the isolation of lepers in the leprosaria likely limited its spread. The pathogen is not very good at dividing and spreading.

strong selection for leprosy resistance allele

gwas

genome wide association studies

observational study of genetic variance associated w a specific trait

snps

variations in the DNA sequence that occur when a single nucleotide in the genome is altered

present to significant degree w/in a population

haplotype

a set of DNA variations, or polymorphisms, that tend to be inherited together

may refer to a combination of alleles or to a set of snps found on the same chromo

selective sweeps

A phenomenon in which a selected allele goes to fixation, carrying with it alleles at tightly linked loci

advantageous mutation is becoming more frequent as selective sweep continues, may be fixed by the end of the sweep

genetic hithchiking

Fixation Index (Fst)

measure of population differentiation due to genetic structure

0= homogenized

measure of genetic variability at a specific locus

What is leprosy?

gram positive bacteria that can be treated with antibiotics

pathogen and host evolutionary arms race examples

antibiotic resistance

host immune responses can drive pathogen evolution

Penicillin is a selective agent

penicillin resistance decreases as public use goes down

Evolution of antibiotic resistance

1. lots of germs few are antibiotic resistant

2. antibiotics kill bacteria causing the illness, protecting body from infection

3. drug resistnat bact are allowed to grow and take over

4. some bact give their drug resistance to other bact, causing more problems

horizontal gene transfer

The transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusions of different organisms.

antibiotic resistance in galapagos tortoises

chickens treated w/ antibiotics

tortoise eats chicken poop

bam! tortoise resistance

host immune response can drive pathogen evolution

ex) the flu mutates antigenic sites every year to continuously infect us

to avoid extinction: the fly must continue to find naive host without antibodies or alter its hemaglutinin so that previously exposed hosts do not recognize it

flu viruses evolve 10^6 faster than mammals

mutation of flu at a steady rate

predicting which strain to use in the development of vaccines

the one w/ the most aa sequence changes is most likely to survive into the next year so this is what we use to make vaccines

flu pandemics

radically different hemagglutinins are a selective advantage

flu strains swap genes

flu strains swap genes

idk slide 46/52

does selection favor virulence?

coincidental evolution hypothesis

shortsighted evolution hypothesis

trade-off hypothesis

coincidental evolution hypothesis:

virulence is a byrpoduct of other traits, like the capacity to reproduce quickly in nature

shortsighted; selection favors strains that reproduce quickly and effectively. By contrast, virions in the nervous system are unlikely to be transmitted and their evolution will likely increase within host fitness

trade off hypothesis:

virulence can be bad from a pathogen perspective bc it leads to host death

virulence vs reproductive rate

as reproductive rate of phages increases virulence also increases

hosts that reproduce more slowly led to lower pathogen reproductive rates and lower virulence than a host that reproduced quickly

vector borne pathogens are more...... than direct contact pathogens

virulent

what is life

cells: membrane bound units in which the membrane regulates the passage of materials

replication: to be considered life, organisms must be capable of self replicaiton

information: life processes hereditary informationin the form of genes. Information is stored and transmitted (genotype) and expressed (phenotypes)

evolution: organisms are the product of evolutoin

energy: life must aquire and use energy

IDA

"Initial Darwinian ancestor—

the first living thing that is an ancestor of extant organisms; also known as the primordial form."

LUCA

last universal common ancestor

dogma of genetics

DNA -> RNA -> Protein

paradox: dna is needed to make enzymes, enzymes are needed to make DNA, so which came first?

RNA world hypothesis

hypothesis that RNA served as the genetic information of early life

gets us away from the dna paradox,,, bc rna can be catalytic and can self replicate

RNA self replication

-RNA has a genotype and phenotype

-but, RNA (and DNA) can only replicate via an enzyme and yet that enzyme did seem to exist in a pre-DNA world

- catalytic rna

can the same replicated RNA sequence have different phenotypes

yes bc of secondary and tertiary structures in rna.

ribozymes

RNA molecules that function as enzymes and can mediate reactions

they have complex tertiary structures

condensation of amino acids in the ribosome in polypeptide fromation

rna splicing

can catalytic rna replicate itself

yes but under experimental conditions

can catalytic rna evolve

yes.

tetrahymena ribozyme, an rna enzyme that catalyzes the cleavage of RNA

efficient self replication in rna

mutually beneficial rna molecules would encounter each other with low frequency if they diffused freely

and would be coopted by other rna molecules if they encoutnered them

compartmentalization would be a key to success

vesicles form spontaneously when phospholipids are shaken in water

rna in a smaller area increases the probability of them finding each other to catalyze reactions

why did dna become dominant

dna is chemically more stable than rna

dna is better at self reoair during replication due to the presence of thymine instead of uracil

dna has better information security because of the protective double helix structure

where did complex molecules come from

the things that make life have either always been around or a meteorite brought it to us

Oparin-Haldane hypothesis

simple organic compounds were changed by heat and solar radiation into more complex organic compounds

how life came to be.

when heated, simple molecules became amino acids

1. assemble simple molecules into building blocks for complex polymers

2. assemble polymers that can store info and catalyze rxns

3. add membranes and an energy source to make a living organism

cells obtaining energy

proton motive force

atp synthase

proton gradient

oxygen as the final electron acceptor

how did luca obtain energy

thermal vents

a natural proton motive force was created

how did luca get off the vent

-to escape luca had to make its own proton motive force

1. carbon and energy metabolism powered by natural proton gradients in an ancestral protocell w a leaky membrane

2. simplified carbon and energy metabolism of archaea. H+ membrane potential generated via an H+ pump

3. simplified carbon and energy metabolism of some bacteria

search for LUCA

earliest recorded life 3.7 bil years ago evident by carbon deposits in fossils

3.26 bil years ago evidence of cell division

search for LUCA through phylogeny

-need a gene present in all organisms that is heavily conserved

-under strong stabilizing selection

ex) small subunit of rRNA os responsible for translation, this is true for all life

what makes it difficult to find LUCA

horizontal gene transfer

how did early life obtain energy

from CO2 and other sources like methane

what organism started photosynthesis

cyanobacteria

oxygen catastrophe

Population of cyanobacteria exploded since they had an advantage, produced more oxygen faster than it could be absorbed, causing it to build up in the atmosphere, which wiped out the other organisms. Methane had been acting as a greenhouse gas that kept the Earth warm, but the extra oxygen reacted with methane to form carbon dioxide and water, which don't trap as much heat. The thin atmosphere caused Earth's first ice age.

but aye we got the ozone layer

Precambrian Era

oldest and longest era : unicellular organisms originated

has a poor fossil record but there is evidence of life in rust and stromatolites

stromatolites

Oldest known fossils formed from many layers of cyanobacteria and sediment.

cyanobacteria were uptaken to create what in modern cells

chloroplasts

Chemoorganoheterotrophs

energy and carbon from organic compounds

were uptaken to make mitochondria

endosymbiosis

engulfing of mitochondria and cyanobacteria

host cell profited from the chemical energy lodger produced

the lodger benefits from the protected nutrient rich environment surrounding it

Cambrian explosion

A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago.

High O2 allowed for fast metabolism, larger body size, selection for increasing organism complexity and exploration of new niches

Genome size and functional complexity

reflect a high demand for energy in more complex organisms

what drove the evolution of eukaryotes

1. evolution of cyanobacteria and oxygen abundance

2. prokaryotes evolved to do aerobic respiration

3. lots of atp could now be used

4. this was a big selective advantage and caused proaerobic respiration

5. large anaerobic prokaryotes endosymbiosed smaller aerobic prokaryotes that produced a lot of ATO