Midterm 1 Flashcards
recondite
understood only by experts or requiring detailed specialized knowledge to be understood only by experts. dealing with difficult material
incredulous
unwilling to belive or unconvinced by something showing or characterized by disbelief
idolent
lethargic and not showing interest or making any effort
Boor
rude obnoxious, ill mannered, crass person
stultify
to diminish somebodies interest and lively state of mind being repetitive tedious or boring
iconoclast
one who challenges traditional belief, customs or values or goes against established practice
salubrious
beneficial to ones health
Nihilist
someone who believers that nothing is worthwhile or that life is pointless and all human values are worthless, completely disregards established conventions, rules or believes
lurird
sickening, horrifying or shocking: sensational, with graphic horror , devastation or violence
desultory
pointless or aimlessly passing for one thing or place or than other, random
parable
a simple story to illustrate a moral or spiritual lesson
redolent
strongly suggestive of smell, having a well defined odor
lilliputian
a person or thing that is unusually small
incorrigible
impossible to change or correct, often referring to someone who is unruly and impossible to manage
purulent
contain or excluding puss
inveterate
fixed in habit or practice or firmly establishes and of long lasting
ingrate
an ungrateful person; somebody who does not show gratitude
venerable
high respected, revered
gesticuate
an expression/gesture with your hands
magnanimous
noble-spirited, generous, kind and forgiving
imprecate
cures, to put something or someone down, to call harm on something or someone
nefarious
completely wicked and immoral
egregious
bad to an extraordinary and outrageous degree
evolution
decent with modification, changes in population allele frequency
homology
similarity resulting from common ancestry, often despite differences in function
analogy
similarity in function but not having the same evolutionary origin
can selective breading lead to evolution?
by selectively breeding mice for the ability to run over 24 generations, the results show that the selected group ran 2.78 times as far than the control
microevolution
small evolutionary changes within species or populations
speciation
lineages split and diverge an ancestral species can give rise to two or more dependent or daughter species
macoevolution
referring to larger phenotypic changes sufficient to place an organism in a different higher taxon. over time microevolution results in both speciation and macroevolution
incipient species
finishing the final stages of speciation
vestigial structures
useless in one species but is important in an ancestor species
explain the case of vestigial features in the Stickleback fish
the marine form is fully armoured. a lake was poisoned to remove all the fish and the marine form was able to move into the lake. the lake favoured the lightly armoured fish b/c it allowed more energy to be used for reproduction
define species
species are groups of interbreeding natural populations that are reproductively isolated from other such groups - individuals within a species resemble each other due to gene flow resulting from interbreeding
what are ring species
a connected series of neighbouring populations where adjacent populations are still able to inter breed. but there are at least two populations of the “ends” of the “ring” that are unable to interbreed - The Siberian Greenish Warbler
the law of succession
fossils in a given geographic region are more closely related to the extant fauna of that region than they are to organisms in a different geographic region
evidence for homology
studies in comparative anatomy, embryology, physiology, and genetics revealed strong similarities across organisms
how did developmental homology resulted in male hernias
in the embryo the testes are positioned high up and eventually descend into the scrotal sac, this leaves a weakening in the abdominal wall where the intestine and protrude
principle of superposition
younger geological layers sit on top of older ones
principle of original horizontality
lava and sedimentary rocks were originally laid down in the horizontal position
principle of cross cutting relationships
rocks the intrude into other rocks are younger than the host rocks
principle of inclusion
boulders or other fragments found in a rock body are older than their host rocks
principle of Faunal succession
more recent fossils are more similar to existing life forms than older fossils
natural selection
differences in the survival and reproduction of phenotypes, leading to differences in their contribution to the next generation, resulting a change in frequency of heritable phenotypic variations.darwin was not the first one to propose evolution. he developed a mechanism that explains how evolution can occur
components of natural selection
living things produce more offspring than can be supported, there is constant struggle for life, individuals in a population vary in their phenotypes, some of this variation is heritable, those individuals who are best adapted to the current conditions are most likely to survive and reproduce, if these adaptions are heritable they will be passed on to offspring. natural selection acts on phenotypes but only if there is a change in allele frequencies not population genotype frequency
evolutionary fitness
refers to an individuals contribution to the next generation in terms of number of offspring, the more offspring an individual contributes to the next generation, the greater the individuals evolutionary fitness
what is contributes to fitness
viability or mortality selection: an individuals ability to survive and reach reproductive age
sexual selection: an individuals ability to procure a mate
fecundity selection: family size, which is usually measured as the number of female gametes/eggs are produced
adaption
is a trait or characteristic that increases an individuals fitness, in comparison to individuals that do not have that trait
natural selection results in adaptive evolution
what are darwin’s four postulates
- individuals within species are variable
- some of these variations are heritable
- more offspring are produced than survive, some are more successful at survival and reproduction
- the survival and reproduction of individuals is not random, those who reproduce the most are those with the most favourable variations and are naturally selected
how did the introduction of the cane toad evoke natural selection
toads had skin glands that make toxic substances, predators that were able to eat the frogs dies off in large numbers.
snakes with large jaws and stout bodies ate the toad and dies, snakes with smaller jaws and slandered bodies could not and survived .
there was a decrease in law sizw and increase in slenderness
how does natural selection operate
NA acts on individuals but consequences are in the populations
nNS acts on phenotypes but evolution consists of changes in allele frequ.
NS id backwards looking, can produce new trains in conjunction with mutation,
NS does not lead to perfection, is nonrandom but not progressive,
acts on individuals not groups
antagonistic selection
when one component of fitness is at adds with another. ex: male peacock feathers are large and require a lot of energy, they they weigh organism down making them easy targets
human induces selection regimes
harvesting practices can impose selection on populations unintentionally
ex: sheep with horns greater then a specified size can be hunted, typically males with large horns are killed prior to breeding giving them a reduced fitness
directional selection for smaller horn sizes
evolution of antibiotic resistance
When individuals don’t complete their dose leaves microbs that hare more resistance to antibiotic - those go off and reproduce making large populations of resistant
types of variation
genetic variation: can possess different phenotypes as a result of genetic differences/ different genotypes
environmental: different phenotypes as a result of exposure to different environment despite identical genotypes
genotype by environment interactions: different phenotypes as a result of the interactions of their genotype with the environment
example of environment integration producing variation
in many reptiles sex is determined by the temp. at which the egg develops. individuals at warm or cool tend to be female while at intermediate temps tend to be male
example of environmental variation
when genetically identical Daphnia were places in habitats with and without phantom midge predation the individuals exposed to predation developed defences
phenotypic plasticity
refers to the fact that genetically identical individuals can have different phenotypes in different environmental conditions
reaction norm
refers to the patter or range of phenotypes that the same genotype can posses as a result of different environments
mutation
any heritable change in the genetic material. is the ultimate source of all genetic variation, provides the raw material for other evolutionary forces such as NA and genetic drift to act on.
point mutations
single base pair changes, transitions are more common than transversions
can be synonymous (dont change AA) or non-synoymous
indels
refer to the insertion or deletion of one or more nucleotides in a DNA sequence, and frequency, result in frameshift
neutral mutations
have no effect on fitness
deleterious mutations
reduce fitness
beneficial or advantageous mutations
increases the fitness
lethal mutations
a deleterious mutation that results in the organisms death before reproduction
example of heterozygote superiority
those heterozygous for the sickle cell and normal are resistant to malaria, homozygous for normal allele are susceptible to malaria.
heterozygote superiority
the heterozygote has a greater fitness than the homozygotes
is the mutation rate subjected to NS
mutation rate is heritable, mutations in DNA pol can effect these rates as can mutations in the genes responsible for repairing BP mismatches.
high mutation rates is beneficial in poorly adapted environments. if individuals are well adapted most mutations will be deleterious
gene duplication
result in loci that retain their function, gain a new function or become a pseudogene and importantly, has also resulted in the evolution of gene families
caused by unequal crossing over.
inversion mutations
result from ionizing radiation and typically involve large regions of chromosomes, affect linkage and gene order
genetic cline
an increase of decrease in the frequency of a gene over geographic distance
polyploidy
large scale mutations- duplication of entire sets of chromosomes. occurs in organisms that can self fertilize or when different species hybridize.
caused by errors in meiosis resulting in diploid gametes
why is polyploidy important
it can result in new species being found
doubled chromosomes can gain new functions allowing adaption
important source of genetic variation in natural populations - in flowering plans polyploid formations occur as commonly as point mutations
what is the classical hypothesis
populations contain very little variation, selection maintains a single best allele at any locus, and heterozygotes are rare. heterozygotes occur as a result of rare deleterious mutations that are quickly eliminated by selection
what is the balance hypothesis
individuals are heterozygous at many loci and balancing selection maintains lots of genetic variability
define balancing selection
any form of selection that results in the maintenance of genetic variability
evidence for the balancing model
protein electrophoretic studies revealed substantial genetic variation
what is the selection hypothesis
balancing selection results in the maintenance of high genetic variability - heterozygotes tend to have a higher fitness
what is the neutral hypothesis
most alleles in natural populations are neutral and dod not affect fitness
define genotype frequency
of individuals of a genotype/N - must add up to 1
how to calculate allele frequ.
2(AA) + (AB) / N
2(BB) + (AB) / N
what is the hardy - weinberg principle
shows us how allele and genotype frequ. behave in natural populations if there are no violations and the population is randomly mating - allows us to predict genotype frequ. from allele
what is a panmictic population
a sexually reporducing populations where each male has an equal probability of mating with each female and each female has an equal probability of mating with with each male
modeling random mating
assuming that genotype frequ. are the same among male ands female and the population is infinitely large , the probability for a given individual to mate with one of a certain genotype is equal to the genotype frequ.
what is the probability that two gametes unite
is equal to the product of the allele frequ.
p^2 qp q^2
what are the assumptions of the HW principle
no selection, no mutation, no migration, infinitely large with panmictic mating, population is diploid, population is reproducing sexually
what does HW teach us
- is a population is out of equilibrium, it will take a single generation of random mating to restore equilibrium
- if there are no violations, the HW principle shows that the genotype and allele frequ. will not change
rejecting the null hypothesis
is the calculated X^2 is less than critical value there is no statistical evidence to reject the null
what is heterozygote deficit
if the observed heterozygosity is less then expected
what are the modes of selection
directional: increase or decrease of the mean, reduced variation
stabilizing: those at both extremes have low survival, no effect on the mean decrease in variation
disruptive: individuals at extremes have a high survival, no effect on mean, increases variation
explain the case of the goldenrod gall
stabilizing selection, if the gall is too small it parasitized by wasps if too big birds
why do natural populations exhibit significant variation and why is it maintained
- populations are not in evolutionary equilibrium with respect to directional or stabilizing selection
- in most populations there is a balance b/w mutation and selection
- disruptive selection may be more common than thought
what is the effect of mutation on HW
mutation will not result in disequilibrium b/c as long as there is random mating mutated gametes will unite and the zygotes will in equilibrium based on the new frequency
has a small impact on allele frequ.
selective sweep
the rapid fixation of a beneficial allele by selection
migration
geen flow, movement of alleles b/w populations after migration there is a change in allele frequ. and the genotype frequ. arnt consistent with HW
in the case of the banded snakes, what is the effect of migration?
the island favours the unbanded, but migration maintains the banded population,
tends to homogenize population in terms of allele frequ
what is F_st
the fixation index, measure of how much a population differ in allele frequ. when equal to 0 the frequ are equal at 1 there are no common alleles
What is genetic drift
the chance fluctuations in an allele frequ. as a result of random sampling gametes b/c zygotes are produced from a random sample of gametes from the initial pool, allele frequ. can change as a consequence of this sampling error.
does genetic drift result in disequilibrium
no, as long as mating is still random the new pool of gametes will randomly unite to form zygotes in equilibrium based on the new allele frequ. most influential when population size is small
what is the probability that one allele will go to fixation?
the chance of fixation is equal to the allele frequ.
what are the effects of random fixation
allelic diversity in a population decreases and the population heterozygosity will decrease over time. the effect of GD is greater when population size is small and the faster the heterozygosity will decline
can limit a population’s ability to evolve in changing environment
the founder effect
when a new population is founded by some colonists, the allele frequ. in this population can differ substantially from those in the parent population
population bottleneck
a sharp decline in population size that can dramatically change the allele frequ. by initial sampling error and subsequent genetic drift
how does the founder effect and bottlenecks effect HW equil.
results in dis equilibrium
after one round of random mating it will be restored
genetic drift and migration
opposite forces, drift increases divergence and F_st but migration decrease
it take little migrations to counter the effects of the drift
what are the effects of non-random mating
can indirectly effect evolution, but does not change allele frequ.
inbreeding
mating among closely related, results in deviation from HWE, increase in homozygosity or decrease in heterozygote deficit
affects all loci
how does inbreeding effect allele frequ.
causes changes in genotype frequ. but not allele frequ.
creates a heterozygote deficit or homozygote excess
not a mechanism for evolution on its own
what is inbreeding depression
a reduction in the average fitness among individuals within a population due to inbreeding - recessive deleterious alleles will occur in homozygotes more often and decrease overall population fitness
outbreeding
the opposite of inbreeding - causes heterozygote excess, doesnt change allele frequ. and on its own isnt a mechanism for evolution affects all loci
assortative mating
positive - individuals with similar phenotypes mate
negative - individuals with dissimilar phenotypes mate
both cause disE with heterozygote deficits in positive and excesses in negative but only at those loci involved in the traits
why is small population is a concern for 3 reasons
- GD will be strong and will reduce heterozygote by randomly fixing alleles removing variation and adaptive potential
- drift can overpower natural selection
- the probability of mating among close relatives increases in small population sized resulting in inbreeding depression
what is the genetic rescue effect
an increase in the average population fitness as a result of an increase in genetic diversity, by introducing individuals which mitigates then negative effects of inbreeding and genetic drift
what are linkage corridors
they connect fragmented and isolated habitats creating a larger habitat where the negative effects of small population size will be less pronounced
where does natural selection apply in the life cycle
Migration - anywhere
Mutation - during gametogenesis
Genetic drift - gametes b/c only a sample forms zygotes - the sampling event is during the gametes
Inbreeding - the non-random union of gametes
Assortative mating - gametes b/c it is non-random mating
Population bottle neck - can occur any where
Founder effect - any can form the founders of a new population
idealisum
all natural phenomena are imperfect representation of true essences of an ideal unseen world
aristotle
further elaborated on idealisum where a deity had creased fixed essences
lamarck
species changed over time - inheritance of acquired characteristics
erasmus
grandfather of darwin, proposed that species are modified decedents of earlier forms
cuvier
catastrophism -earth features had been primarily modeled by catastrophes
hutton
principle of uniformitarianism - geological processes that we see today are the same as those of the past
lyell
presented evidence for uniformitarianism ended catastrophism
wallace
independently arrived to a similar conclusion as darwin
Dawin’s evolutionary theory
- all species, living and extinct, have descended without interruption from one or a few original forms of life
- theory of natural selection
modern synthesis or neo-darwininan synthesis
the mathematical description of the way in which genes behave.
a heterozygote deficit can be causes by
positive assortative mating, inbreeding, selection (heterozygotes have inferior fitness), migration,
and asexual reproduction.
a heterozygote excess can result from
selection, outbreeding, negative assortative mating, migration or asexual reproduction
