ch 13- evolution Flashcards
polytomy/ multifurcation
an internal node of a
phylogenetic tree that leads to more than two tips.
parsimony
means the simpler the evolutionary
explanation, the better. Phylogenetic trees
minimizing evolutionary reversals, convergent evolution and parallel evolution are preferred.
anagenesis
describes the gradual evolution of an
interbreeding population without splitting.
cladogenesis
refers to the splitting apart of
evolutionary lineages (formation of new clades).
internal node
An internal node is a branch point on a cladogram, and represents the splitting (divergence) of a single group into two descendant groups.
cladogram
type of phylogenetic tree that
shows such inferred evolutionary relationships
among various biological species.
monophyletic vs paraphyletic
Phylogenetic trees can either be monophyletic (an
ancestor and all its descendants) or paraphyletic
(ancestor and some but not all of its descendants).
phylogenic tree
A phylogenetic tree is a branched diagram that shows inferred evolutionary relationships between different taxa.
clade
cluster with an ancestor and all its descendants.
batesian mimicry
a non-harmful muanimal resembles a harmful one.
mullerian mimicry
two poisonous animals resemble each other to warn their predator.
aposematic coloration
(warning coloration): Vibrant coloration in poisonous animals to warn predators.
crypsis
Similar to camouflage, except
includes olfactory (smell) or auditory
methods of concealment (ex. scent masking, silencing).
camouflage
(cryptic coloration): Match
appearance to environment to avoid
detection. Strictly visual method of
concealment.
coevolution
Two species impart selective
pressure on each other. Classic examples are
hummingbirds and flowers.
parallel evolution
Species diverge from a
common ancestor but undergo similar changes.
convergent evolution- homoplasy
Unrelated species adapt to similar environments becoming
more alike (analogous structures).
divergent evolution
Species diverge from common ancestor.
sympatric speciation
Occurs without a
geographical barrier.
balanced polymorphism
polyploidy
hybridization
hybridization
Some hybrids are more fit
than purebreds.ol
polyploidy
In plants results from
nondisjunction during meiosis. (e.g., two 3n
organisms, usually sterile, meet and are
reproductively compatible).
balanced polymphormism
polymorphism: Different phenotypes are isolated within the same
area.
allopatric speciation
Occurs due to a
geographical barrier.
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.
phyletic graduation
Evolution happened
gradually via accumulation of small intermediary
changes. Not likely to be true (not supported by
fossil evidence).
punctuated equilibrium
Short spurts of
evolutionary changes during periods of stasis
(supported by fossil evidence).
speciation
is how species form, starting with
reproductive isolation, which leads to interruption
of gene flow between populations that gradually
develop into two species.
postzygotic isolation types
refers to barriers to
organism success after zygote has formed.
hybrid motality (inviability)
hybrid sterility
hybrid F2 breakdown: Hybrid F2 generation have reduced fitness compared to their parental generation.
prezygotic isolation
habitat isolation
temporal isolation
behavioural isolation
mechanical isolation
gamete isolation (incompatibility)
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.
what are the factors causing microevolution
is the process when gene
frequencies change within a population over
generations (favorable genes increase, unfavorable
decrease).
what are the factors causing microevolution
genetic drift
non random mating
mutations
natural selection
gene flow: migration- non random moving alleles between populations leading to variation through mixing
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.
sources of genetic variation
mutation
sexual reproduction
balanced polymorphism
polyploidy
balanced polymorphism
Maintains a variety of
phenotypes within a population.
● Heterozygote advantage (e.g., sickle cell
anemia): Two parents produce an offspring
that is more fit than either parent.
● Minority advantage: Rare phenotypes offer
higher fitness. Cycle between high and low
frequency (e.g., advantageous against
hunters’ search images).
● 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.
paleontology
is the study of fossils through
actual remains of the animal or their traces (ichnofossils). Petrification is the process by which living organisms turn into fossils. These fossils allow us to see the development of
species through time by comparing deepest
(oldest) fossils to shallowest (youngest).
what do chordates have during development
gill slits
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, e.g. bird wings and
bat wings.
vestigial structures
serve no purpose but
are homologous to functional structures in
other organisms, e.g. human appendix and
cow cecum.
cuvier
proposed catastrophism. Catastrophes
lead to mass extinctions of species in those areas. The different populations in different areas were shaped by what catastrophes had occurred, and what random organisms
lamrach
● Use and disuse: used body parts will develop and unused ones are weakened, leading to evolution.
● 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.
darwin
theory of natural selection
Natural selection is the gradual, non-random process where allele frequencies change as a result of environmental interaction. Survival of the 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.
Leads to the evolution of the population (not individuals).
what are the requirements for natural selection
- Demand for resources exceeds supply: results in
competition for survival (fittest survive to pass
on genes). - Difference in levels of fitness due to variation in
traits: differentiate ability to compete and
survive (e.g., black peppered moths favored over
white moths during Industrial Revolution). - Variation in traits must be genetically-
influenced (heritable) to be passed onto
offspring.
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.
.
types of natural selection
- Stabilizing selection: Mainstream (average) is
favored (e.g., birth weight). Diagram follows a
standard bell curve. - Directional selection: One extreme favored (e.g.,
longest giraffe neck allows access to the most
leaves). - Disruptive selection: Rare traits favored,
mainstream is not (e.g., snails living in low and
high vegetation areas).
artificial selection
Carried out by humans to
selectively breed for specific traits (e.g., dog breeding).
hardy weinberg formula
calculates genetic
frequency during genetic equilibrium (no change in
gene frequencies). If both equations hold true, the
population is under Hardy-Weinberg equilibrium.
p+1=1
p^2+ 2pq + q^2= 1
