Biology Test 2

9/17 probability in genetics up until 10/20

Mendels Law of Segregation

In diploid organisms, two alternate, homologous alleles segregate and are passed separately.

Mendels Law of Independent Assortment

alleles of a gene are passed independently of eachother (rules of random probability)

Phenotypic ratio based on Law of Segregation

3:1

Phenotypic ratio based on Law of Independent Assortment

9:3:3:1

To find the greatest number of ways a specific number of distinct things can be arranged (ordered)

n!

use this if theyre asking probability of getting 1,2,5, in any order.

Gamblers Fallacy

The mistaken belief that if something occurs repeatedly, the universe would make it balance in the future, but this is not the case (theres an reverse of the fallacy too)

Working hypothesis

guiding research question

Null Hypothesis

(HW) statement that you are trying to DISPROVE. First analytical Hypothesis

Alternative Hypothesis

often reflects the working hypothesis, needed if you reject the null (reject that randomness prevails)

difference between research question and hypothesis

if you know more, go to the hypothesis cause u can make predictions

Accepted alpha value

0.05. (If there is a 5% chance or less that our data match the null, we can reject the null.)

there is a 1/20 percent chance you reject the null when it is actually right.

Ways of testing significance

chi-square test

p and its relationship to a

probability that the null is correct. If it is less than or equal to alpha, we reject the null hypothesisoi

if p is greater than 0.05 (alpha).. then

we fail to reject the null hypothesis

Chi-Square formula

degrees of freedom

number of possible categories - 1 = df

Why are allele frequencies multiplied together in the HW equilibrium equation

because they are all independently passed from one generation to the next

If there are more than 2 alleles in the population at the same locus…

(p + q + w +z) x (p + q + w +z) = 1.0 is an example of 4

What did we think before HW

Dominant traits would COMPLETELY dominate recessvie

OR alleles would be 50/50

AND/OR the only wal alleles change frequency was through sexual reproduction

HW says…

p and q always the same

Assumptions of HW model

Random mating, No mutations

No migration

Infinite population size (sorta) and NO NATURAL SELECTION

What happens when assumptions are violented for HW

HW does not apply. If allelic frequency does not match from one gen to the next, you blame one of the assumptions being false

HW as a null

HW is a null as it is caused by randomness, standard. Usually use this as evidence that one of the assumptions is violated and causing a change in the population (evolution)

Cheetahs

very few genetic variation, violating HW, inbreeding as nonrandom mating

extinction vortex

point of no return for the population until extinction

HW works best in….

overly large populatuions (think of # of coin flips)

Bottlenecks:

gene pool is significantly reduced for some reason and decreases allele diversity

Cheetahs: 2 bottlenecks ice age and poaching causing them to violate 2 HW assump: nonrandom mating and small population sizes.

Genetic Drift

constant chancing allele frequencies due to randomness, not adaptive

Genetic drift is NOT violation of HW because

its within what randomness would predict is okay. HW only looking from generation to generation.

Gene flow:

movement of individuals their alleles from one pop to another. Makes pops look more alike genetically. can increase and decrease allele diversity

What causes allele diversity to increase

mutation and gene flow

Genetic drift really effects what groups?

bottlenecks and founder events

founder events

similar to bottleneck,  relatively small group of individuals that have separated form the source population The source population still exists, but the small group kinda migrates away. the act of them going and the thing that caused them is called the founder event`

mutation

occurs from a DNA replication error and change in nucleotide sequence. increase genetic variation by creating new alleles, random w respect to fitness, but however most mutations lower fitness

junk DNA

where most mutations occur, differs from most everyoneee

Assortative mating

more likely to mate with someone w similar phenotype (beetle size) good: keep good genes

Disassortative mating

more likely to mate with someone with other phenotype (grey wolves mate w different colors) Good: diversity

inbreeding

mating w someone w close ancestor, increases homozygosity (dom and recessive) and decrease heterozygosity, does not cause evolution since allele frequ does not change. Different from assortative bc all loci are effected

Inbreeding Depression

loss of fitness,evolution dosent change bc allele freq stays the same, only genotypes change. “loss of fitness as homozygosity increase and heterozygosity.”

Why is homozygosity a problem

We need dominant alleles to function,  rr is loss of function allele. however a lot of our disease resistance is better when were heterpzygous (in comparison to homo dom) SICKLE CELL and maleria

Inbreeding very common in plants but…

self fertilizing decreases fitness

peacocks competing selective pressures

want to be flashier for women, but are more susceptible to predators/cannot fly

male-male competition

not sorted by females— only males

sexual dimorphism

two sexes look different. Not always caused by sexual selection tho.

Taxnomic Hierarchy in order

Domain Kingdom Phylum Class Order Family Genus and Species

rule for binomial nomenclature

Genus species italics/underline

prefixes super and sub

superorder and subfamily

Kingdoms

Protista, Plantae, Fungi, Animalia, (Bacteria, Archea used/are domains, everything else is eukarya)

what is a species

evolutionarily independent group, meaning mutation, selection, and drift act on the group independently of what’s happening to others.

3 different criteria for designating species

Biological, morphological, and phylogenetic species

biological species concept

not interbreed/ no viable offspring

prezygotic isolation

before syngamy, include temporal (breeding at diff times) habitat, hehavioral, gamatic barrier (incompatible gamates, mechanical (genitalia incompatible)

postzygotic isolation

offspring die as embryo or do not reproduce

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the biological species concept is not good for….

distinguishing species in the fossil record or whose populations do not overlap (they cannot interbreed_)

morphospecies concept:

species based on size, shape, behaviors. To be different, they have been seperated long enough. works better with fossilized/extinct species.

phylogenetic species concept

looks at variety of traits specific to the population to see relatedness between groups, and therefore distincion between them. Species can be determined by morphological, behavioral, or genetic differences.

hat is phylogenetics

reconstruiction of the evolutionaty history of populations

nodes

points in time when an ancestral group split into 2 ore more descendent groups. SPECIATION EVENT

terminal nodes

ends of branches to represent a group, living or extinct

Phenetics as analysis

grouping of species by similarty of traits, weighing them all the same (cows are more different than the lugnfish and goldfish)

cladists as analysis

grouping based on recently derived characteristics only (cows and lungfish are more related than the goldfish) more trustworthy lowk

monophyletic group

most recent common ancestor and alll its descendants
come from the same node

paraphyletic group

most common ancestor and not all of its descendents. clarify loss of traits or convergance.

cladists POV

independent evolution of a trait across multiple genetic lines is less likely than the trait evolving once, especially for the traits that have more recently evolved.

homology

traits due to same ancestry

homoplasy

traits similar due to other reasons other than common ancestry

convergent evolution

common cause of homoplasy: natural selection causes independent evolution of certain traits where the common ancestor does not have the trait

parsimony

the simplest explanation is probably the explanation

allopatric speciation

physical barrier, no gene flow, divergance due to genetic drift, accumulation of mutations, natural selection…

dispersal in allo[patric speciation

group emigrates away, isolated long enough to have allele changes to lead to a new species

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Sympatric Speciation

different preferences (philopatric apple vs hawthorne) they live in the same space and will not interbreed

what happens when newly formed species come back into contact

reinforcement: hybrids have less fitness (sterile) further speciation would occur.

hhybrid zones

new species: if new hybrid traits can be selected for, and genes passed onto the next geenration.

Why do chloroplasts with chlorophyll a b and β-carotene

for wider spectral sensitivity – in green
algae and all land plants – evolved for early competition for sunlight.

major characteristics for Kingdom plantae

diff chlorophyll, multiple membrane layers in chloroplasts, Thylakoid condition, cell wall, starch as energy storage product

cell wall

protection and structurall support

thylakoid condition

stacked and flattened vesicles without connection to the inner of two membranes enclosing the chloro, for more efficient extraction of radiant energy

evolution of photosynthesis

from early unicellular bacteria, pigment can absorb radiant energy and transform it into high energy chemical bonds

water absorbing radiant energy

mostly red, so it looks blue. natural selection favored plants who were able to get out of the water even just a little

evidence of early competition for energy sources in aquatic enviroment

elongated cells to reach sun/co2

increased fibers and streaming to distribute energy

using cellulose and others to strengthen cell membranes against predation

new niches

plants strengthening their cell membranes

due to competition: Cellulose, silicon and calcium carbonate were used by the photosynthetic protists to strengthen their cell membranes against predation, with cellulose becoming the
common constituent of the cell wall of all land plants. This physical protection could also
protect those protists pushed to the edge of the sea in the splash zone along ancient shores

challenges of life on land for plants

dehydration, structure, transport of water and root cells, reproduction, harmful ultraviolent/blue radiation (some pigments evolved to absorb blue wavelengths)

Nonvascular plants with cuticle

Aquatic, nearshore/freshwater, ?? Division (phylum) Chlorophyta (Green algae)?? Ex: charales, branched, multicellular, chlorophyll-using, stoneworts, NO specialized tarnsport tissue

Non-vascular plants with cuticle

part out of water has cuticle for dehydration resistance, lack of support structure (and vascular tissue) result in low sprawling growth, first to have stoma, water intake by diffusion, gametophyte (haploid) is dominant life cycle stage. 3 divisions.

3 divisions (phyla) of the NONvascular plants WITH cuticle

mosses, liverworts, and hornworts

largest phylum of NONvascular plants W cuticle

Bryophyta (mosses)

The NONvascular plants w cuticle are..

first land plants (mosses) but NOT anncestors of higher plants

sphagnum moss (NONvascular with cuticle)

during drought becomes dormant until water returns

Vascular Seedless plants

first plants with true vascular tissue, limited into moist enviroments bc of reliance on flagelllated sperm (ferns). The Sporophyte (diploid) is the dominant life cycle stage, as in all higher land plants.

4 major divisions of the vascular, SEEDLESS plants

club mosses, horestails, whisk ferns, ferns.

largest phylum of vascular SEEDLESS plants

pteridophyta (ferns) largest leaves, many epiphytes, oldest vascular plants, ancient 20m high tree ferns

vascular naked-seed plants (gymnosperms)

pollen, SEED, dehydration-resistant seeds for sexual reproduction on land, (no fruit inhibits some seed dispersal)

4 major divisions of vascular, naked-seed plants

cycads, ginkgos, gnetophytes, conifers

Largest Division of vascular, naked seed plants

coniferophyta (pines, spruces, firs)

what includes the largest (redwoods) and oldest (brisle cone pine) plants

vascular naked seed plants

seed as a major innovation

protects embryo from water loss, herbivores, permits domancy, and promotes dispersal

pollen as a major innovation

Cones of males (small) and females (large) usually in separate trees; scales partially protect
female megaspore (eggs). Needles of conifers reduce the photosynthetic surface, but this feature in combination
with pollen allow conifers to thrive in more arid habitats

Vascular plants w Fruit covered seeds (angiosperms, the flowering plants)

the largest number of species of all plants, flower, fruit, diversity, mostly annuals