Variation among individuals

what are the three kinds of variation?

genetic variation 

environmental variation 

genotype-by-environment interaction 

( ) variation: the genotype is the only source for phenotypic variation

genetic 

( ) variation: The phenotypic variation is caused by an environmental factor that alters gene expression (phenotype changes to buffer the environmental change-temporary)

environmental

What are some examples of genetic variation?

eye color

skin color

hair color

down syndrome

what are some examples of environmental variation?

plants in shaded environments grow taller to reach the light

sun tanning

( ) interaction: a gene is expressed or not based on the environment

genotype-by-environment

What is an example of a genotype-by-environment interaction?

sex determination in some species based on temperature

variation in ( )’s sequence can lead to changes in protein sequences 

genesp

( ) are the functional blocks of life → proteins perform all ( ) functions → changed in protein sequences might alter their ( )

proteins

metabolic

function

( ): different versions of a gene. One particular individual may carry more than one version of the same gene

alleles

genes are passed from ( ) to ( ) 

parents to offspring 

genetic variants associated with higher survival and reproductive success ( ) become more common in populations over time→ adaptation by ( )

i.e. fitness

natural selection

variants associated with untimely death and reproductive failure will ( ) 

disappear quickly 

genetic variation is the raw material for ( )

evolution

evolution: ( )

genetic change at the population level that is passed over generations (note that its genetic change, not natural selection or adaptation!)

Environmental phenotypic variations is also known as?

environmental effects

environmental effects happen when ( ) , regardless of their genetic makeup, show changes in their traits because of the ( )

all individuals

environment

the environment influences phenotype in the ( ) across all genotypes 

same way 

“If you give a group of plants the same genotype but grow them in nutrient-poor soil, they’ll all be shorter than if they were in nutrient-rich soil,” is an example of what type of variation?

environmental effects

genotype-by-environment (GxE) phenotypic variation is when the ( ) depends on the ( )

environment

genotype

some crop varieties grow better in drought than others. The “same environment” (drought) leads to different outcomes depending on genetic differences. what is this an example of ?

GxE phenotypic variation 

In environmental variation alone, ( ) phenotype shifts in ( ) direction when the environment changes.

everyone’s

same

in ( ): different genotypes respond in different ways to the same environmental change creating variation among individuals 

genotype-by-environment variation 

Out of the three kinds of variation what is the the most common?

trick question none is more common than the others

Many organisms alter the identity and quantity of the proteins they make in response to changes in the ( ) → altering the ( ) 

environment 

phenotype 

What’s an example of environmental variation in human athletes?

Human athletes living at low altitude, but training at high altitude, produce more vascular endothelial growth factor (VEGF) than athletes living and training at low altitudes → environmental variation.

Despite the benefits in the short term for individuals displaying environmental variation → it does NOT supply raw material for ( ), environmental variation is not transmitted to future generations.

evolution

There is one mechanism of ( ) inheritance that involves the chemical modification ( ) of ( ) in the ( ) → ( ) 

non-genetic

addition of a methyl group 

cytosine nucleotides 

DNA chain

epigenetic marks

( ) may be transmitted from parent to offspring because they are copied during DNA replication

Epigenetic marks

epigenetic marks allow individuals to ( ) to their offspring, and sometimes their grad-offspring, useful information about the state of the environment they are likely to encounter, epigenetics should, in principle, serve as raw materials for ( )

“communicate”

evolution

how is epigenetics and phenotypic variation important for evolution?

phenotypic variation- even if it is not inherited it can help bugger small environmental changes while a potentially beneficial mutation arises 

epigenetics- some epigenetic tags can be passed down to descendants helping increasing their fitness

How are we able to identify when epigenetics is affecting gene expression?

the tags on the DNA can be identified and quantified (epigenetic marks)

In genotype-by-environment (GxE) interaction, the expression of a gene is influenced by the ( )

environment

in GxE the ( ) develops different phenotypes based on the environment. GxE is very ( )

same genotype

common

The relationship between the genotype, phenotype, and environment is a graph called ( ) 

reactive norm

populations living in a variable environment in which different phenotypes have a higher fitness at different times and places can evolve a plastic response that allows individuals to develop ( ) suitable for the conditions which they find themselves, GxE interactions can serve as ( ) for evolution

phenotypes

raw materials

Is their such thing as temperature dependent alleles?

yes, bunny example

What is phenotypic plasticity?

the ability of an organism to change its physical traits or behaviors in response to change in environment during its lifetime.

Where do new allele come from?

new alleles arise from alterations to existing alleles

point mutations ( ) vs ( ) (insertion or deletion of several bases, mutations are ( )

substitution of one base for another

indels

random

What are the types of mutations?

transition→ purine for purine, pyrimidine for pyrimidine 

transversion

synonymous (or silent) substitution 

nonsynonymous (or replacement) substation

nonsense mutation

indels

Mutations can alter ( ) function

protein

What are the two mechanisms of gene duplication that are thought to be among the most common sources of new genes?

unequal crossing over and retro position or retroduplication

what is unequal crossing over?

error in the genetic recombination that happens during meiosis

What is retroposition or retroduplication 

processed messenger RNA that is reverse-transcribed into double stranded DNA and it gets integrated into one of the chromosomes. tents to be a pseudogene (nonfunctional)

some mutations can alter the gross ( ) of chromosomes

morphology

what is gross morphology

the study of an organism’s structure and form at a macroscopic level

Some mutations affect gene ( ) and ( ) , others produce duplications or deletion that affect the ( )

order

organization

total amount of genetic materials

Inversions are a ( ) process, ( ) causes two double-strand breaks in a chromosome, after breakage, the chromosome segment can ( ), ( ), and ( ) in its original location

multistep

radiation

detach

flip

reanneal

Genome ( ): this mutation involves the entire set of chromosomes in an organism, such as ex a and b

duplication 

a) sister chromosomes fail to segregate during meiosis l

b) sister chromatids do not separate properly during meiosis ll 

-resulting cells make have double the number of chromosomes of the parent cell.

organisms with more than two chromosomes are said to be ( )

polyploid

polyploidy is common in ( ) and rare in ( )- self-fertilization is more common in plants

plants

animals

why is polyploidization important to evolution?

can lead to new species being formed

it alters cell size, cell geometry, and gene dosage→ may endow individuals with new phenotypes 

There is ( ) among individuals

variation

Individuals differ because they carry different alleles ( ), because they have experienced different environments ( ), and because the different alleles/ genes they carry cause them to react differently to the environment ( )

genetic variation

environmental variation

GxE interactions

Genetic variation and GxE interaction is the raw material for evolution→ carried to ( ) 

descendants 

The ultimate source of genetic variation are mutations ( )

changes in nucleotide sequences

Mutations can be small ( ), ( ) or can entail ( )

(point mutations)

indels

the duplication of entire genes and genomes

most mutations are ( ), some are ( ) and some are ( ) 

neutral 

deleterious (can be lethal)

beneficial

Mutations are RANDOM but due to natural selection, ( )

beneficial mutations are likely to accumulate, and the population means fitness will increase