DAT bio chapter 13 evolution Flashcards
Evolution is the gradual development and
change of ______ (allele frequencies) in
populations over successive generations.
Evolution increases ______
heritable traits
biodiversity.
What is embyrology
embryological
similarities and differences between early
stages of related organisms. Eg. all chordates
have a gill slit during development.
what is comparative anatomy
compares different
body parts of different animals:
Homologous structures:
may or may not
perform the same function but have a
common ancestor. eg. forearm of bird and
forearm of human.
Analogous structures:
same function, do
not have a common ancestor. eg. bird
wings and bat wings.
Vestigial structures:
serve no purpose
but are homologous to functional
structures in other organisms eg. human
appendix and cow cecum.
Biochemical methods allow for waht
DNA sequence comparisons. Can see conserved DNA sequences (higher similarity = higher relatedness) and common conserved pathways (eg. Krebs cycle).
Who proposed catastrophism?
Cuvier
What is catastrophism
mass extinctions of species in areas. different
populations in different areas were shaped
by what catastrophes had occurred, and
what random organisms then survived and
populated that area.
Who proposed use and disuse and inheritance of acquired traits
lamark
What is use and disuse?
used body parts will
develop and unused ones are weakened,
leading to evolution.
what is Inheritance of acquired traits:
traits acquired through use and disuse are passed onto offspring (eg. giraffe stretching neck will cause its neck to develop, and produce long necked offspring). This is incorrect - acquired characteristics are generally not heritable.
What is natural selection?
gradual, non-random
process where allele frequencies change as a
result of environmental interaction.
What is survival of the fittest?
fittest occurs as individuals with greatest
fitness (ability to survive and produce viable
and fertile offspring) have greatest success, and
pass on more DNA to future generations
compared to less fit parents.
parents. Leads to the
evolution of the population (not individuals).
requirements for natural selection 1
Demand for resources exceeds supply:
results in competition for survival (fittest
survive to pass on genes).
requirements for natural selection 2
Difference in levels of fitness due to variation
in traits: differentiate ability to compete and
survive (eg. black peppered moths favored
over white moths during Industrial
Revolution).
requirements for natural selection 3
Variation in traits must be genetically-influenced (heritable) to be passed onto
offspring.
requirements for natural selection 4
Variation in traits must be significant for
reproduction and/or survival: genes
improving reproductive success/survival are
favored and increase over generations and
vice versa.
3 types of natural selection
stabilizing selection
directional selectin
disruptive selection
Stabilizing Selection:
mainstream (average)
is favored (eg. birth weight). Diagram follows
a standard bell curve.
directional selectin
one extreme favored
(eg. longest giraffe neck allows access to the
most leaves).
disruptive selection
Selection: rare traits favored,
mainstream is not. (eg. snails living in low
and high vegetation areas).
Sexual Selection:
non-random mating between
males and females. Females favor high quality
partners, males prefer high quantity of partners
to increase their number of offspring.
Note: traits selected for may be favorable for
reproduction but not for survival.
Artificial Selection:
carried out by humans to
selectively breed for specific traits (eg. dog
breeding).
What does hardy weinbery formula calculate?
calculates genetic frequency during genetic equilibrium (no change in gene frequencies). If both equations hold true, the population is under Hardy-Weinberg equilibrium.
Mnemonic for the requirements for hardy weinberg equilibrium
(Mnemonic: Large, Random, M&M)
● Large population: minimizes genetic drift.
● Random mating
● No mutation
● No natural selection
● No migration (gene flow): population must
be isolated.
When conditions are not met, evolution occurs.
What is microevolution?
process when gene
frequencies change within a population over
generations (favorable genes increase,
unfavorable decrease).
Factors Causing Microevolution
- Genetic Drift: allele frequencies change by
chance. Larger effects on small populations.
● Bottleneck effect: smaller gene pool,
some alleles may be lost (eg. disaster
killing majority of population).
● Founder effect: some individuals migrate
away from the population. - Non-random Mating: sexual selection,
outbreeding, inbreeding. - Mutations: can be dormant until
environmental change allows it to flourish. - Natural Selection: no luck involved
- Gene Flow: migration (non-random) moving
alleles between populations, leading to
variation through mixing.
Sources of genetic variation
- Mutation: must not be fatal.
- Sexual Reproduction: crossing over,
independent assortment and random joining
of gametes. - Balanced Polymorphism: maintains a
variety of phenotypes within a population.
● Heterozygote advantage (eg. sickle Cell
Anemia).
● Minority Advantage: rare phenotypes
offer higher fitness. Cycle between high
and low frequency. (eg. advantageous
against hunters’ search images).
● Hybrid Advantage: Two strains of
organisms produce more superior
offspring.
● Neutral Variations: may become
beneficial if the environment changes. - Polyploidy: plants have multiple copies of
alleles introducing more variety and
preserving different alleles. Can also mask
effects of a harmful recessive allele.
What is macroevolution?
is long-term and occurs at a
level at or higher than species.
Species are
reproductively isolated (via prezygotic and
postzygotic isolating mechanisms) resulting in a
lack of gene flow between species.
Prezygotic isolation (macroevolution)
prevents fertilization
from occuring between species.
Types of prezygotic isolation
Habitat Isolation: occupying different habitats. ● Temporal Isolation: reproducing at different times/seasons. ● Behavioral Isolation: different courtship rituals. ● Mechanical Isolation: male and female genitalia are not compatible. ● Gamete Isolation: gametes do not recognize / fertilize each other (eg. zona pellucida on mammalian oocytes).
Postzygotic Isolation: (macroevolution
Isolation: backup in case hybrid
zygote forms.
Types of postzygotic isolation
● Hybrid Mortality: hybrid zygote not-viable (often due to different chromosome numbers). ● Hybrid Sterility: hybrid zygote sterile. ● Hybrid F2 Breakdown: offspring of hybrids have decreased fitness.
Speciation is how species form, starting with
________, which leads to
interruption of _____between populations
that gradually develop into _______
reproductive isolation
gene flow
two species.
Allopatric Speciation: happens when
occurs due to a
geographical barrier.
Type of allopatric speciation
Adaptive Radiation: occurs when many species arise from one ancestor as they adapt differently to their environments. During adaptive radiation, species can specialize to fill different niches within the same environment.
Sympatric Speciation: happens when
occurs without a
geographical barrier.
Types of sympatric speciation
● Balanced Polymorphism: different phenotypes are isolated within the same area. ● Polyploidy: in plants results from nondisjunction during meiosis. (eg. Two 3n organisms - usually sterile - meet and are reproductively compatible). ● Hybridization: some hybrids are more fit than purebreds.
What is phyletic gradualism (theories of macroevolution)
evolution happened
gradually via accumulation of small
intermediary changes. Not likely to be true (not
supported by fossil evidence).
What is punctuated equilibrium? (theories of macroevolution)
short spurts of
evolutionary changes during periods of stasis
(supported by fossil evidence).
What is divergent evolution?
species diverge from
common ancestor.
What is Convergent Evolution (Homoplasy):
unrelated species adapt to similar
environments becoming more alike
(analogous structures).
What is parallel evolution?
species diverge from a
common ancestor but undergo similar
changes.
What is coevolution?
two species impart selective
pressure on each other.
Types of coevolution?
● Camouflage (cryptic coloration): match appearance to environment to avoid detection. ● Aposematic Coloration (warning coloration): vibrant coloration in poisonous animals to warn predators. ● Mimicry: evolving to resemble another species. In Batesian mimicry a non-harmful animal resembles a harmful one. In Mullerian mimicry, two poisonous animals resemble each other to warn their predator.
What is a phylogenetic tree?
branched diagram that
shows inferred evolutionary relationships
between different taxa. A clade is a cluster with
an ancestor and all its descendants.
What is Cladogenesis
refers to the splitting apart of evolutionary lineages (formation of new clades).
What is anagenesis?
describes the gradual evolution of
an interbreeding population without splitting.
What is parsimony?
means the simpler the evolutionary
explanation, the better. Phylogenetic trees
minimizing evolutionary reversals, convergent
evolution and parallel evolution are preferred.
Big bang timeline
14 billion
earth is how old
4.5 billion
prokaryotes are how old
3.5 billion
eukaryotes are how old
2 billion
earths current atmosphere has how much nitrogen oxygen and argon
● Nitrogen gas (most common) = 78%.
● Oxygen gas = 21%.
● Argon gas = 0.9%.
● Trace amounts of CO2
, methane, ozone.
Primordial earth p1
Earth’s primordial atmosphere consisted of
_____ and ______ - it was a
reducing environment.
inorganic compounds
no oxygen
Primordial earth p2
Earth cooled down, gases condensed to
form the _____
primordial sea
Primordial earth p3
Simple compounds became more _____,
organic compounds ____
complex
formed.
Primordial earth p4
Organic monomers became _____ to
form _____behave like proteins).
polymers
protenoids (
Primordial earth p5
______ arose: precursors to cells. Had
microsomes (membrane-like) and proteinoids.
Protobionts
Primordial earth p6-7
Heterotrophic prokaryotes form. 7. Autotrophic prokaryotes form (eg. cyanobacteria - can photosynthesize). ● Important: The development of autotrophs led to the \_\_\_\_\_\_ and its accumulation (oxidizing environment forms).
production of
oxygen
Primordial earth p 8
Oxygen accumulates, reacts with UV light to
form _____, which blocks UV. This
terminates _______.
ozone layer
abiotic chemical evolution
Primordial earth p 9
Primitive eukaryotes form ● \_\_\_\_\_\_\_ membrane-bound organelles (mitochondria, chloroplasts), once free-living, were phagocytosed by other prokaryotes and lived in symbiosis with them as organelles.
Endosymbiotic theory:
Primordial earth p 9
More _____ eukaryotes and multicellular
organisms begin to _____
complex
evolve.
What is the organic soup theory
believed that oxygen in the
primordial atmosphere must have been too
reactive for organic chemicals to be produced,
and therefore oxygen must have been lacking in
the primordial atmosphere. Strong energy (eg.
lightning, volcanic heat, UV radiation) drove
reactions that formed organic compounds.
Who proposed the organic soup theory
oparin and haldane
what experiment mimicked the reducing environment proposed by opain and haldane?
Miller Urey experiment
what was the miller urey experiment?
Set up a flask containing inorganic compounds
and simple organic compounds but no oxygen
(CH4
, NH3
, H2
, H2O) connected it to another flask
with electrodes (simulates lightning) and heated it
up (simulates high temperatures). Complex organic
compounds (amino acids, organic acids, but no
complete nucleic acids) were formed. Supports
the Organic “Soup” Theory.
