Final Exam - Lecture Notes

macroevolution

macroevolution

What does this diagram depict

microevolution

These examples show what type of evolution

• some bird species evolving larger beaks to eat from backayard bird feeders

• Lizards are growing longer limbs and stickier toes for climbing buildings

• Fish and pets are developing resistance to human pollutants and posionsmi

phenotype

• an individuals observable characteristics e.g height , eye colour

• also physiology, behavior etc. colour blindness, lactose intolerance

genotype

an individual’s genetic make up

• can be described from all of an indvidual’s genetic material, or from a subset

Locus

location of a particular gene is called a

allele

a version of a particular gene is called a

a locus is a location of a particular gene (gene ID) and an allele is a version of a particular gene (A or a)

What is the difference between a locus and an allele

Genotype (subset) = aa or Aa ( one genotype per individual) and an allele = a or A ( two alleles per locus per individual)

Compare Genotype vs. locus. vs allele

Germ-line mutations

what mutations occur in reproductive cells (vs. somatic mutations)

Recombination

the mixing and matching during meiosis. shuffles mutations to produce new sequences

neutral, deleterious and advantageous

What three things can mutations be?

neutral

• mutations that has no effect (doesn’t change encoded protein, or occurs in noncoding DNA)

deleterious

mutations that are harmful (in protein-coding gene regions)

advantageous

mutations that create an improved chance of survival or reproduction - RARE!! (and depends on environment)

substitution

what type of mutation is this

insertion

what type of mutation is this?

deletion

what type of mutation is this?

Natural Selection

results in adaptations ( thanks to darwin?)

Fitness

measured as reproductive success ( often also influenced by longevity)

no

Did Darwin know anything about genetics?

Mendel

who worked with peas rediscovered in 1900

• (also led to confusion re genetic variation wrt discrete traits (green vs yellow)

Fisher

who recognized that many traits are controlled by multiple genes?

modern evolutionary synthesis

The contributions of Darwin+ Mendel + Fisher and other created our current understanding of evolution called the

Positive selection

selection that increases the frequency of an advantageous trait

Frequency

how common is an allele in a population ( 50 % = _____ of 0.5)

increase

overtime selection _____ (increases or decreases) the frequency of an advantageous allele within a population

dominant allele

An allele that expresses its phenotypic effect even when heterozygous with a recessive allele;

recessive allele

A type of allele that when present on its own will not affect the individual.

negative selection

selective removal of alleles that are deleterious

balancing selection

selection that maintains two or more alleles (different phenotypes)

• e.g heterozygote advantage

stabilizing selection

a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value

• Instead of favoring individuals with extreme phenotypes, it favors the intermediate variants.

directional selection

• occurs when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other.

• shifts the population mean

artificial selection

an evolutionary process in which humans consciously select for or against particular features in organisms

disruptive selection

A form of natural selection in which extreme values for a trait are favored over intermediate values, causing subpopulations of a single species within the same habitat to develop different adaptations.

Intrasexual selection

interactions between individuals of one sex

intersexual selection

interactions between males and females

Genetic drift

random evolutionary change

• result of chance events - non-random nothing to do with adaptation

evolution

What does genetic drift lead to

population bottlenecks

reduce genetic diversity

• when population recovers it doesn’t magically reclaim diversity

• genetic drift continues to eliminate alleles when population remain small

m = neutral mutation

what does m equal

• note its fate is influenced by chance events\

• neither adaptive or delterious

fixation

the only remaining allele ( 100% or frequency of 1.0)

small,large

Genetic drift can be very important in __ opulations and much less important in ____ populations

reduces

Migration _____ ( increase or reduces ) genetic variation between populations

Migration makes populations -______ ( more or less ) similar to one another

1. in conservation genetics isolated populations are a concern - without gene flow, they lose genetic diversity from genetic drift, and small population become inbred

2. if maladapted individuals migrate to a new area, they will be selected against- although weakly maladapted individuals can impact new populations

List two reasons why gene flow can be important source of genetic variation

allele

Non random mating alters genotype frequencies without affects ____ frequencies

Inbreeding

a form assortative mating

homozygosity

mating between relative can lead to increased ________

• can leads to inbreeding depression because inbred offspring are more likely to have two copies of a deleterious recessive allele

molecular evolution

New mutations arise - over time

• Fixation following drift or selection

• Elimination following drift or selection

• Maintained at intermediate frequencies (balancing selection)

different mutation become fixed in different population

Time since most recent common ancestor

the amount of time that two species have been isolated from each other

different

species that have been isolated from each other for a long time should have ______ genetic differences from each other compared to species that have been isolated from each other for a short time

Molecular clock

the number of genetic differences among species can give clues about how much time has passed since they diverged froma common ancestor

• can vary a lot and have to be calibrated for different genes and different taxa

chordata

a phylum of the animal kingdom comprising all animals that have, at some stage in their life, a notochord ( a hollow dorsal nerve cord), pharyngeal slits and a muscular tail extending past the anus

• includes subphyla Cephalochordata, Urochordata, Vertebrate (vetebrates)

species

real biological entities

• often look different from one another

• nothing static

Biological Species Concept

• Groups of actually or potentially interbreeding populations that are reproductively isolated from other groups

morphospecies concept

concept that says if it walks like a duck , its a duck

( Note there are cryptic species that look very simillar)

asexual species

Biological species concept can not define what type of species?

ecological species concept (ESC)

different species have different niches

• resources and habitats

phylogenetic species concept (PSC)

all members of a species descended from a common ancestor

• long ago all life on earth had a common ancestor

( very recently: not all famliy members have the same most recent common ancestor)

prezygotic and postzygotic

What two things make up reproductive isolation?

pre-zygotic

eggs arent fertilized

could be

• behavioral isolation

• temporal isolation (flowering time in plants)

• gametic isolation (fertilization attempts fail - abalone proteins on sperm surface need to interact with eggs)

• mechanical incompatibility (genitals don’t fit - Drosophilia example)

• ecological isolation ( lady buys: henoseplachna yastomiia dn H. niponica feed and mate on different host plants)

post zygotic

eggs are fertilized

• usually because of genetic incompatibility

behavioral isolation

when species are reproductively isolated from others due to differences in behavior.

temporal isolation

when two or more species reproduce at different times.

gametic isolation

a type of prezygotic barrier where the gametes (egg and sperm) come into contact, but no fertilization takes place.

mechanical incompatibility

a physical incompatibility between reproductive organs of two organisms.

ecological isolation

form of reproductive isolation, wherein habitat preferences of species lowers the probability of mating.

reproductive isolation

When two population separate from each other, their genetic similarity decreases over time and eventually leads to ______

allopatric speciation

-different place

• speciation isn’t instant - intermediate stage sometimes recognized as subspecies

dispersal and vicariance

One population can divide in to the following

dispersal

migration of taxa into different geographic areas across preexisting geographical barriers such as mountain chain.

vicariance

separation of taxonomic groups due to the appearance of new geographic barriers such as oceans, mountains,

peripatric speciation

a peripheral place

• a small population is isolated or near the edge of a larger populatin

• population is smaller

• th environment may be different in ____ population

adaptive radiation of Darwin Finches

ecological opportunity + allopatric (peripatric ) speciation =

co- speciation

speciation in one taxon leads to speciation to another

ex.

parasite that has one host species

host species undergoes speciation and become two

parasite population now also split into two will eventually also speciate without gene flow

sympatric speciation

• happens in the same place

• speciation in the same geographic place

• gene flow can prevent speciation by sharin alleles between groups

• Natural selection

instantaneous

speciation can be ____ in plants

• hybrids may retain two complete sets of parental chromosomes e.g diploid parents (two sets of chromosomes ) and tetraploid hybrids (four sets of chromosomes)

viable and fertile

Hybrids can be ___ and ___, and if they can not interbreed with parents (reproductive barrier ) = new species

allopolypoids

( allo= different, poly= mutiple, ploid = fold)

• results from hybridization between two different species

Autopolyploids

( auto- self)

• breeding between members of the same species in which meiosis fails , gamete is not haploid

Darwin

the idea of descent with modification (aka evolution) - common ancestor comes from

1. nested pattern of similarities among species on present-day earth

2. Historical pattern of evolution recorded by fossils

What two patterns help us understand how 10 million species evolved in - 3.5 billion years

phylogeny

shows the history of descent with branching ( multiple descendants over time)

phylogenetic trees

provide hypotheses of evolutionary relationships (taxonomy classifies organisms)

( note why a hypotheses, they provide the best explanation or the relatedness among organisms based on existing data)

closest relatives

species are considered to be _____ if they share a common ancestor not shared by any other species/group = sister groups

monophyletic group:

a common ancestor plus all its descendants

paraphyletic group

includes some but not all, of the descendants of a common ancestor

polyphyletic group

does not include the last common ancestor of all members (convergent evolution)

1. inherited from a common ancestor ( common ancestry) = homologous traits)

2. Independently evolved in two different lineages

What are the two reasons why taxa have characters in common

synapomorphy

a shared, derived trait

outgroup

comparator that is closely related, but less so than the members of the group are to one another (represents ancestral traits_

parsimony

the simplest tree (fewest number of evolutionary changes ) is favored

distance based tree

based tree assumes constant rate of evolutionary change

the fossil record

• evidence that supports phylogenetic hypothesis

• show that groups which branch from early nodes in phylogenies appear early in the geologic record- and allow us to infer time since divergence (molecular clock calibration)

• Provide a record of extinct species

• Link species to the environment ( e.g metorite = huge changes dinosaur extinction)

• organisms muse be buried in order to be fossilized

• marine life more likely to be fossilized than terrestrial

Why is the fossil record incomplete

Hard parts of the organisms

Which parts of the organism are more likely to be preserved as fossils?

( clams vs, nematode worms, pollen vs flowers, diatoms vs amoebas)

trace fossils

insight into behavior and anatomy, e.g feeding trails of snails and trilobites

molecular fossils

ancient DNA from 100,000 year old neanderthal bones are an example of

preserved

Occasionally whole organism with delicate parts including flowers, seaweeds, mushrooms , embryos are _______

geological time scale

The fossil record produced ______ showing major events in the hisotry of life on earth