unit test 2 (Ch.18-20) Flashcards
What are taxons?
A way to classify the diversity of organisms
What do taxons include?
kingdom-King
Phylum-Phillip
Class-Cried
Order-Out
Family-For
Genus-Good
Specis-Sex
How was it determined that the earth was a lot older than originally thought (Think James Hutton)?
erosion work over long periods of time in geology
What did Malthus identify?
That the human population could outgrow their supply of food
what was a consequence of Malthus’ claim?
population growth was slowed
what did Lamarck propose?
organisms could change over time based on 2 principles
what are the 2 principles that Lamarck proposed about the changing of organisms?
-Use and disuse
-Inheritance of acquired traits
What is an example of use and disuse of an organisms physical properties?
A giraffe’s neck could elongate if a food source was out of reach
How did Darwin come up with his claim that the earth is much older than we think?
-geologicl processes occur very slowly
What did Darwin say about populations and their food?
if populations grew faster than their food supply, this applied to animals as well. This could influence subsequent generations to be more suited to their environments.
What did the inheritance of traits from 1 generation to the next imply?
Organisms become better suited to their environments as the environments themselves change
Where did darwin find most of his evidence for adaptations, ‘inheritance characteristics that improve survival in an environment and increase reproductive success’?
Galapagos islands
What was the 2 main ideas of Darwin’s theory?
-Natural selection
Descent with modification
What are the pressures that Darwin considered on organisms in an environment ?
-resources are finite and limit population growth (next generation won’t thrive)
-Limited resources can lead to organisms to struggle to survive (Organisms will fight for their life)
-Characteristics of individuals in a population vary greatly (no one is exactly the same in characteristics)
-Not all individuals in a pop. will reproduce succesfully (organisms better suited to their environment –> leave behind better offspring more suited to their environment = Fitness)
what does fitness mean in evolution?
Reproductive success of an individual
Greater fitness means that the organism will leave…
More offspring tha individuals that display less fitness
Over generations, traits providing adavantages in a given environment will accumulate in a population. What is this called?
natural selection = survival of the fittest
What does it mean when the generations are slightly different that the genrations before that?
descent with modification
does evolution work on individuals?
No only on populations
does evolution act on traits that aren’t heritable?
No only heritable traits
what is an example of evidence for evolution?
Soapberry bugs feed on fruit with the help of beak length
-If beak length is variable and heritable, we might expect beak length to vary in 2 populations (1 in south Florida and 1 in central Florida) which they do!
what is homology?
describes a characteristic that is similar between organisms as a result of common ancestry
What causes the characteristics of organisms to be no longer identical?
adaptive radiation
what is adaptive radiation?
where organisms evolve and adapt to new environments, causing modifications to original characteristics.
what is an example of adaptive radiation?
human, cats, whales and bats all display similar bones in their limbs; humerus, ulna, radius, carpals, metacarpals..
what is an example of homologous structures?
embyos of varius animal species;
embryos of fish, amphibians, reptiles and mammals display **similar structures early in development **which develop into homologous structures in adulthood
what are analogous structures?
characteristics that are similar between unrelated organisms
do analogous structures evolve from common ancestry?
no, they eveolve from similar selective **pressures **from their environment
What is an example of analogous structures?
the wings of bats, birds, and insects:
common ancestors of these organisms did not have wings but* selective pressures* in the environment caused them to evolve wings
What was Pangaea?
Supercontinent, all continents put together
what supports the theory of Pangaea?
Fossil record and carbon dating these fossil
what is a population?
all individuals of the same species that live in a particular place at the same time
do individuals in a population vary in their traits?
yes
how does variation occur in a population?
selective pressures from the environment and** inheritance of genes**
how is evolutionary change inherited?
1 generation to the next
what do individuals of a population share? (think genetics)
same number of genes
since there is a lot of variation in populations and individuals in a population share the same number of genes, what is an important cause of the variation which is linked to their genes?
alleles
what is a gene pool?
all alleles for all genes present in a population
True or False? diploid organisms can have 3 alleles for each gene
no, it can only have up to 2 alleles
do the 2 alleles of diploid organisms represent all the possible alleles for a gene?
no, there are more possible alleles for that gene
what is microevolution?
Includes
-creation of new alleles from mutations
-the change in proportions of alleles in a population’s gene pool from 1 generation to the next
what is a basic (easy) defenition of microevolution?
if proportion of individuals of any genotype changes from 1 generation to the next
what is genotype frequency?
proportion of a specific genotype in population
Ex: there are 490 individuals with the genotype AA in a population of 1000 so the genotype frequency is 0.49
what is an allele frequency?
proportion of a specific allele in a population
Ex:
-490 AA
-420 Aa
so 490 x2 + 420=1400
total number of alleles in this population is 2000 (All A & a’s)
allele frequency = 1400/2000= 0.7
What does it mean if the allele frequency is changing over generations?
evolution is occuring
how do allele frequencies change?
influence of outside factors
what does Hardy-Weinberg Principle explain?
if allele & genotype frequencies do NOT change over time, population is NOT evolving
what do we say if there is no change in allele or genotype frequency?
populaion is at equilibrium and NOT evolving
Is it rare for a population to be in Hardy-Weinberg equilibrium?
Yes, because microevolution includes ANY force or pressure that could CHANGE proportion of alleles or genotypes in 1 generation to the next
what could prevent a population from evolving? (5)
-no mutations
-Random mating
-No natural selection
-having an extremely large population size
-no migration (transfer of alleles from another population)
What does ‘p’ represent in H-W equation (p+q=1)
p= frequency dominant allele
what does ‘q’ represent in H-W equation (p+q=1)
q= frequency of recessive allele
Say there is
-320 C^RC^R
-160 C^RC^W
-20 C^WC^W
what is ‘p’ in H-W equation?
C^R is the dominant allele…
p= frequency of dominant allele
320x2 (C^RC^R)=640
+160(C^R)
=800/1000 (pop.)
=0.8 is ‘p’
what is p^2 in the H-W equation
(p^2 + 2pq + q^2 = 1)
p^2 = AA freq
(homozygous dominant)
what is ‘pq’ in H-W equation ?
(p^2 + 2pq + q^2 =1)
pq= Aa freq
(heterozygous)
what is ‘q^2’ in the H-W equation?
(p^2 + 2pq + q^2 =1)
q^2= aa freq
(homozygous recessive)
What equation do we use for the allele frequencies for a gene with only 2 alleles?
p + q =1
what type of equation do we use for expected genotype frequencies?
p^2 + 2pq + q^2 =1
what factors cause microevolution? (5) (think opp of what causes no variation through generations)
-Mutations
-Choice of mating partners
-natural selection
-Genetic drift
-Gene flow from migration
what do mutations cause?
changes in genetic sequences –> new alleles
what does natural selection cause?
selects best suited individuals (survival of the fittest)
What does fitt mean in evolution terms?
best suited individuals will often be chosen for mating because they create better offspring
what is the cause of genetic drift?
a random sample of a small group of organisms from a large population
what is the cause of gene flow?
flow of alleles into or out of a population VIA** migration**
what is sexual recombinations?
produces new combinations of alleles–> produce genetic variation that natural selection relies on
if in 1 generation the allelic frequency is 0.7 for genotype C^R and changes in generation 2 to 0.5 then to generation 3 being 1, what type of factor is causing this type of evolutionary change?
genetic drift
what are 2 examples of genetic drift?
-Bottleneck effect
-Founder’s effect
Both randomly change the frequency of alleles
true or false? Genetic drift simply randomly selects individuals from a larger population to continue perpetuating species
true
what is the bottleneck effect?
genetic drift example that happens when the number of individuals in a larger population is drastically reduced by a disaster.
what is the founder’s effect?
genetic drift example that happens when individuals become **isoalted from a larger population **
Does gene flow cause a population to gain alleles or lose?
Both. 1 population might gain some and the other might lose Vise-versa
In gene flow, what does the mixing of individuals from different populations result in?
reduces differences between populations over time
what is the only factor that can cause adaptive evolution?
**natural selection **leads to **adaptation **of an organism to it’s environment
what is macroevolution?
combination of positive mutations and natural selection
will natural selection create entirely new genotypes?
no, it will only increase the frequencies of certain genotypes
true or false? natural selection increases the frequency of beneficial alleles?
yes
how does natural selection increase the frequency of beneficial alleles?
1-beneficial alleles arise due to a mutation
2-natural selection occurs –> proportion of alleles in gene pool increase
3-Beneficial allele eventually replace all other alleles in a population
what is a negative selection?
natural selection that decreases frequency of harmful allele
what is a positive selection?
natural selection increases the frequency of a favorable allele
what effects can natural selection have on the distribution of phentoypes in a population? (3)
-directional selection
-disruptive selection
-stabilizing selection
what is directional selection?
-shifts a population’s phenotypic traits in 1 direction or the other of a curve
-population’s environment changes or members of a population migrate to new habitat.
an example of directional selection?
resistance of microbes to antibiotics: Antibiotics selects for microbes that already have resistance which make the bacteria multiply and thrive..not good
what is Disruptive selection?
when conditions favor individuals at both extremes of phenotypic range for example
small-billed birds feed on soft seeds but large-billed birds specialize in cracking hard seeds
What is stabilizing selection?
conditions act against both extreme phenotypes and **favours intermediate **variants
out of the 3 selections, which reduces variation?
stabilizing selection
what is speciation?
process of which 1 species **splits into 2 or more new species
what is marcoevolution?
evolutionary change above species level over long periods of time
what does evolutionary theory explain?
how new species originate in addition to how populations evolve
what is a species? (think a human and a cat)
individuals that can breed with eachother in nature to produce viable offspring
what does the biological species concept emphasize?
reproductive isolation
what causes memebers of common species to not be able to reproduce with eachother?
reproductive barriers
what are the 5 types of prezygotic barriers? (zygote never produced)
-habitat isolation
-temporal isolation
-behavioral isolation
-mechanical isolation
-gametic isolation
why can’t the common species mate if habitat isolation is implied? (prezygotic)
because the 2 species occupy different habitats so they can’t mate
why can’t 2 common species mate when temporal isolation is implied? (prezygotic)
the 2 species breed during different times of the day, month, years so the species can’t mate
why can’t 2 common species mate when behavioral isolation is implied?
because the 2 species mating calls/ rituals don’t attract eachother
why can’t 2 common species mate when mechanical isolation is implied?
the 2 species **cannot physically have sex **because of morphological differences.
why can’t 2 common species mate when gametic isolation is implied?
sperm of 1 species cannot fertilize eggs of another species
what are the 3 postzygotic barriers?
-reduced hybrid viability
-reduced hybrid fertility
-hybrid breakdown
what is reduced hybrid viability? (postzygotic)
genes of different parent species interact in ways that impair hybrid’s development or survival
what is reduced hybrid fertility?
hybrids are healthy but sterile (can’t reproduce)
what is hyrbid breakdown? (postzygotic)
1st generation hybrids= viable and fertile
but when they mate, they can’t produce offspring that will be able to reproduce
how can we define a species? (3)
-morphological species concept
-ecological species concept
-phylogenetic species concept
what does the morphological species concept define?
characterizes a species by it’s body shape, size and structural features
how does an ecological species concept define a species?
views species in terms of it’s ecological niche
how does phylogenetic species concept define a species?
phylogenetic history of organisms
how does speciation occur?
reduced gene flow
what are the 2 ways gene flow is reduced?
-allopatric speciation
-sympatric speciation
what is allopatric speciation?
geographic separation of populations which restricts gene flow (genes in and out of a population)
what is sympatric speciation?
geographically overlapping populations when biological factors like chromosomal changes and non random mating reduce gene flow.
is there physical separation in sympatric speciation?
no, a population experiences different selective pressures without physical separation.
how does sympatric speciation occur? (2 ways)
-change in behavior
-change in habitat (niche with same geographic area)
what does sexual selection help?
maximize reproductive success
what are the 3 types of sexual selection?
-intersexual selection
-intrasexual competition
-mate choice
what is intersexual selection?
selects features that make an organism more attractive to the opposite sex
what is intrasexual competition?
selects features that help an individual intimidate or** fight off same-sex rivals**
what is mate choice? (like a dating show)
selection of nonrandom process in which females select males based on a certain appearance
What is the handicap theory? (think of how hard it must be to raise a handicap kid)
they are indicator traits that suggest their features are condition-dependent and have a cost. If individuals can handle the cost, it can suggest superior genetic quality
What is the Hamilton-Zuk hypothesis?
an extension of the handicap theory that posits **sexual ornamnets **are indicators of parasite and **disease-resistance **
what gender is intrasexual competition more apparent in?
male-male features = competition for the female
can speciation cause major changes in physical appearances over time?
yes
can natural selection anticipate future environments by selecting for characters that will suit a future environment?
no,
what is evolutionary novelties?
changes in genetics lead to phenotype changes which lead to changes in adult phenotypes.
what can evolutionary novelties arise from?
-gradual refinement of existing structures
-major changes in body can result in developmental **genes **or genes that control spatial organization of body parts
how are mutations in genes that control spatial organization formed?
products of 1 class of genes; Hox genes = provide positional information in an animal embryo
what happens if Hox genes are duplicated?
1 gene will continue coding for proteins that regulate normal development
what could happen if further mutations were to happen to these hox genes?
can give rise to new physical features
