Topics 4-6 Flashcards
What is genetic and phenotype variation?
genetic: diversity of alleles in a population
phenotype: variety in visible expression of “types”
List five factors that can changes allele frequency? ( aka the causes of evolution )
- natural selection
- sexual selection
- mutations
- gene flow
- gentic drift
* make sure to review each individually*
What is the difference between the founder effect and the bottleneck effect?
founder effect: is when small part of a population seperates from the main group and starts a new population
bottleneck effect: a catastrophic event wipes out a lot of the population, rare alleles are more likely to be lost
What are the main details of directional selection?
- extreme phenotype favoured
- response to steady change in the environment
- loss of gene variation
- directional shift in the mean of the population
What are the main details of distruptive selection?
- extremes are favoured
- results in polymorphism
- maintains genetic variation ( loss of phenotype )
What are the main details of stabilizing selection?
- common phenotype favoured
- selection AGAINST the extremes
- average conditions stay the same
- little or no evolutionary change
What is negative frequency - dependant selection & heterozygote advantage?
neg freq - dependant: rare genotypr has the advantage
heteo advantage: ex) sickle-cell anemia, the heterozygous allele has the advantage
What is mircoevolution?
evolutionary change below the species level ( occurs mainly through selection or drift )
What is macroevolution?
evolutionary change above the species level
( mass extinctions, speciation, apperance of higher taxa )
note: ‘game changers’ aka the big events
What is the Biological Species Concept?
” consists of a group of actually or potentially interbreeding individuals that are reproductively isolated from other such groups “
Define pre-reproductive and list the prezygotic isolation mechanisms
prevents two individuals from forming a zygote
- ecological ( habitat selection )
- temporal ( different time of day/season )
- behavioral ( courtship patterns )
- mechanical ( anatomically incompatiable )
- gamete isolation ( sperm & egg can’t fuse )
Define post-reproductive and list the postzygotic isolation mechanisms
occur after a zygote has formed
- zygote death
- hybrid infertility ( offsrping can’t reproduce )
- hybrid inviability ( lower fitness )
What is speciation?
the formation of new & distinct species in the course of evolution
What is the difference between cladogeneis &anagenesis?
cladogeneis: branching or spiltting of a lineage
anagenesis: evolutionary change within a lineage, resulting in differences between sister lineages
What is the difference between allopatric and sympatric speciation?
allopatric: population sibdivided by a geographical barrier
sympatric: subgroups formed within a continous habitat, the subgroup can stop mating with the original pop. and the possibility of a new species could occur
What is gradualism?
slow differentiation by natural selection over any generations ( Darwin )
What is punctuated equilibrium?
speciation happens rapidly followed by relatively long periods of stasis ( then no change )
What is abiogeneis?
idea that life arose from non-life more than 3.5 billion years ago, note: the first life forms were simple and through a gradual process became increasingly complex
A fossil is most likely to be fossilized if…?
- has a hard body
- was aquatic
- closer to inshore
- decomposing organisms are absent
What is the difference between relative and radiometric dating?
relative: stratigraphy
- can’t tell specific date it was fossilized
- can tell which came first, second, third, wtc
radiometric: focuses on looking closely at C-12 and C-14 which is then converted to N-14 as the organisms began to decay
Explain continental drift?
the land masses drifting on plates “floating” on hot mantle, the tectonic boundaries are locations for sites of earthquakes and volcanoes
What are the four steps that formed life?
- inorganic compounds
- organic monomers
- polymers
- membrane enclosed compartment
Describe Step 1
inorganic atmospheric gases ( CO2, N2, H, methane )
—> huge amounts of energy ( lightning, deep sea thermal vents and collisions )
organic molecules ( sugar, lipids )
Describe Step 2
organic acids ( nitrogenus bases, sugars ) ---> proteins ( enzymes, nucleic acid ) - RNA monomers produced spontaneously from simple molecules
Describe Step 3
- life reproduces: DNA molecules carry genetic info
- life requires energy: metabolism
- needs to seperate it self from the environment ( cell membrane )
Protocells = spontaneous formation of hollow lipid cells ( bi-layered structure )
Describe Step 4
first genetic matieral: RNA
- single stranded, fragile, self-replicating - can catalyze many different reactions - favoured by natural selection ( RNA World )
genetic matieral of all living organisms today: DNA
- double helix
- very stable structure
- more accurately replicated ( also favoured by
natural selection
Where did life originate?
hot, mineral ruch deep sea vents & clay
- where many of the earliest derivate prokaryotes live
What are some alternative theories?
- extraterrestial origin
- special creation
What did Miller mimick in his experiment?
tried to replicate conditions from early earth ( can’t reproduce the exact conditions ) but created the basic building blocks
