(Inheritance, Genetics, And Evolution) Introduction To Evolution

Front 1

Explain Darwin's theory of 'Descent with Modification'.

Back 1

- Biological populations change over successive generations

- Life evolved from a common ancestor

- History of life is like a tree with branches representing thediversity of life

Front 2

What is 'Natural selection'

Back 2

- Gradual, non-random process by which biological traitsbecome more or less common in a population throughdifferential reproductive success = fitness

Front 3

What are the propositions underlying Darwin's theory of evolution through natural selection?

Back 3

- More individuals are produced than can survive

- There is therefore a struggle for existence; AKA competition

- Individuals within a species show variation

- Those with advantageous traits will survive and reproduce

- Favourable traits will accumulate over generations

- Changes in environment can lead to new traits being advantageous

Front 4

What is 'Sexual selection'?

Back 4

- Animals develop features to help themto maximise their reproductive success

Key to Darwin’s theory of Sexual Selection;

- By making themselves attractive to the opposite sex (intersexual selection,between the sexes

- By intimidating, deterring or defeating same-sex rivals (intrasexual selection,within a given sex)

Front 5

What is 'Artificial selection'?

Back 5

- Intentional breeding for certain traits,or combination of traits = Domestication

- Human preferences/selective breeding

- Used by Darwin as analogy to natural selectione.g. fancier pigeons

Front 6

What are the differences between Archaea and Bacteria?

Back 6

Archaea;

- Archaea are prokaryotic cells

- Membranes of branched hydrocarbonchains attached to glycerol by ether linkages

-Cell walls contain no peptidoglycan

- Not sensitive to some antibiotics that affectthe Bacteria, but are sensitive to someantibiotics that affect the Eukarya

- Unique ribosomal RNA

Bacteria;

- Bacteria are prokaryotic cells

- Membranes of unbranched fatty acid chainsattached to glycerol by ester linkages

- Cell walls contain peptidoglycan

- Sensitive to traditional antibacterial antibioticsbut are resistant to most antibiotics thataffect Eukarya

- Unique ribosomal RNA

Front 7

What does 'symbiosis' mean?

Back 7

- Interaction between two different organisms living in close physical association, typically to the advantage of both.

Front 8

What are the three types of symbiosis?

Back 8

Mutualism;

- Both the symbiont and host benefit

Commensalism;

- The symbiont benefits with little effect on the host

Parasitism;

- The symbiont benefits to the detriment of the host.

Front 9

What are Mendel's laws?

Back 9

Law of dominance;

- In a cross of parents thatare pure for contrasting traits, only one formof the trait will appear in the next generation

Law of segregation;

- During the formation ofgametes (egg, sperm), the two allelesresponsible for a trait separate from each other. Alleles are then recombined at fertilisation,producing the genotype for the trait of theoffspring

Law of independent assortment;

- Alleles for different traits are distributed togametes (and offspring) independently of oneanother

- Mendel bred true breeding plants with yellowround seeds (YYRR, gamete YR) against greenwinkled seeds (yyrr, gamete yr)

- F1 had genotype YyRr and yellow round seedphenotype

- F2 showed phenotypes in ratio of 9:3:3:1consistent with an independent assortmentmodel

Front 10

What is the 'Chromosome theory of inheritance'.

Back 10

- The nuclear substance controls the form and functionof every cell, and divides at mitosis to give equalproducts

- Eggs must lose half their nuclear substance in the polarbody before fertilization, and this must be replacedexactly by the nuclear substance of the sperm

- Because sexual reproduction depends on addingtogether the egg and sperm nuclei in every generation,there must be a halving of the nuclear substance in bothmale and female germ cells

- There are no essential differences between thenuclear substance of eggs and sperm

- Sexual reproduction is a means of producing variabilitybetween individuals, on which natural selection can act

Front 11

Explain the different ways in which gene mutations can affect an individual.

Back 11

Advantageous;

- Give a selective advantage andpassed on to offspring

Selectively Neutral Mutations;

- No effect andare passed to offspring - also known as SilentMutations

Deleterious;

- Harmful and result in the death ofthe cell or individual, normally prior toreproduction

Front 12

What is the Hardy-Weinberg equilibrium used to calculate?

Back 12

- Predicted frequencies of genotypes underthe hypothesis that population is not evolving

- Compare predicted values to the real (measured)ones to check if the population is evolving or not.HW equilibrium allows to detect if evolutionaryforces are acting upon a population

Front 13

What is a Bottleneck effect in relation to genetic drift?

Back 13

- If size of a population isreduced drastically and quicklythe progeny of survivors mighthave allele frequencies differentfrom those of the originalpopulation

Front 14

What is the 'Founder effect'?

Back 14

- A few individuals from a population start a newpopulation with allele frequencies different fromthe original one

Front 15

When does 'Gene flow' occur?

Back 15

- When individuals from one distinctpopulation move to another, interbreed, so bringing adistinct set of alleles to the recipient population

Front 16

What are the four main discoveries that led to modern synthesis?

Back 16

- Macroand Micromutations and Genetics of Populations

- Mutational analysis

- Taxonomy and population genetics

- Palaeontology

Front 17

What is a macromutation and what is a micromutation?

Back 17

Macromutation;

- A mutation of large phenotypic effect; one that produces a phenotype well outside the range of variation previously existing in the population. Mutations with effects in early stages of development can have large phenotypic consequences

Micromutation;

- A small-scale or highly localised mutation; especially: one involving alteration at a single gene locus (point mutation)

Front 18

What is mutational analysis?

Back 18

- Gene mutation analysis is now a fundamental part of the investigation and management of an individual and their family with an inherited disorders

- Its a look at a mutation found in DNA

- These mutations can be found via PCR

Front 19

What are the main points for taxonomy and population genetics?

Back 19

- Genotype not phenotype determinesa species

- Natural populations are genetically variable

- Differences between species and populations can be experimentally shown to have a geneticcomponent. Most are polygenic

- Natural selection does occur in natural populations

- Speciation occurs when geographically separate populations become geneticallydifferent

Front 20

Does palaeontology support or appose evolution?

Back 20

- It shows morphology does change

- It shows that these changes maybe gradual over a long time

- But It also shows change mayhappen rapidly over few generations

Front 21

What are the rules of the modern synthesis?

Back 21

- Genetic variation in populationsarises by chance through mutation, gene segregation and recombination

- Evolution consists of changes inthe frequency of alleles between one generation and anotherdue to genetic drift, gene flow and naturalselection

- Most genetic changes haveindividually slight phenotypic effect

- Diversification comes about by speciation

Front 22

What are the differences between Darwin and Modern Synthesis?

Back 22

- It recognizes several mechanismsof evolution in addition to natural selection

- It recognizes that characteristics are inherited as discrete entities called genes. Variationwithin a population is due to the presence ofmultiple alleles of a gene

- Itpostulates that speciation is (usually) due to the gradual accumulation of small genetic changes. This is equivalent to saying that macroevolution is simply a lot of microevolution

Front 23

What is the Biological species concept?

Back 23

- "Species are groups of interbreedingnatural populations that are reproductively isolatedfrom other such groups“

- Must produce viable fertile offspring

Front 24

What isolation mechanisms exist?

Back 24

Prezygotic barriers: no chance to mate

- Geographic isolation

- Mechanical isolation

- Temporal isolation

- Behavioural isolation

Postzygotic barriers: incomplete fertilisation or not fertile hybrids

- Gamete incompatibility

- Hybrid mortality

- Hybrid breakdown

- Hybrid infertility

Front 25

What is hybridisation and speciation?

Back 25

- Formation of new species or ‘extinction’ (fusion)of 2 and more species

Front 26

What is the phylogenetic species concept?

Back 26

- Species are a group oforganisms whose membersdescended from a commonancestor and who all possess acombination of certain defining,or derived, traits

- Uses the concept ofcladogenesis (branching ofspecies)

- Morphological species concept

Front 27

What are the features leading to speciation?

Back 27

1) Variation

2) Isolation

3) Decreased gene flow

4) Selection

5) Divergence

6) Speciation

Front 28

What is 'Allopatric speciation'?

Back 28

- Speciation bygeographic isolation

- Barriers prevent two or more populationsfrom mating leading to separation

Front 29

What is the difference between Vicariance and Dispersal?

Back 29

Vicariance;

- The geographical seperation of a population, typically by a physical barrier such as a mountain range or river, resulting in a pair of closely related species. New species form on each side.

Dispersal;

- a population migrates over an already existing geographic formation, creating a new species, whilst the old one stays rhe same

Front 30

What is 'Sympatric specifation'?

Back 30

- New species evolvefrom a single ancestral species whileinhabiting the same geographic range.

Front 31

What is 'Peripatric/Parapatric speciation'?

Back 31

- Smallperipheral populations which exploit adifferent niche

- Peripatric similar to allopatric

- Parapatric similar to sympatric

Front 32

What is an 'Ecological niche'?

Back 32

- The rolethe species plays in theecosystem and includes thetype of food it eats, where itlives, where it reproduces, andit relationships with otherspecies.

Front 33

What is the difference between a "fundamental (theoretical)" and the "realised" niche?

Back 33

Fundamental (theoretical)niche;

- Full range ofenvironmental conditions andresources an organism canpossibly occupy and use,without limiting factors

Realised (actual) niche;

- Partof fundamental niche that anorganism occupies as a resultof limiting factors present

Front 34

What are the forces of evolution?

Back 34

- Mutations

- Genetic drift

- Selection

- Migration (gene flow)