test 1 Flashcards
a structure that has no apparent function in one species, yet it is homologous to a functional organ in another (human embryos tails that disintegrate before birth)
vestigial
effects of gene flow
a new individual will add new alleles to the original population, reducing genetic differences between the two groups
how many mass extinctions have we seen in the past 500 million years?
5
used to assign an age to a fossil by testing either the fossil itself or the sediments above and below the fossil, either way, the dates are usually expressed in relation to the present
absolute dating
hybrid inviability (hybrid embryo may die before reaching reproductive maturity), hybrid breakdown (some species produce hybrid offspring that are fertile when those hybrids produce their offspring may have abnormalities), hybrid infertility (some hybrids are infertile)
postzygotic barrier examples
t or f: Mendel was also studying inheritance at the same time as Darwin but neither of them knew of each other
true
hypothesis on how life developed from single-cell to multi-cell
the origin of multicellularity ushered in the possibility of specialized cells, which allowed for new features such as attachment to a surface or an upright orientation
population, or group of populations, whose members can interbreed and produce fertile offspring
how Mayr described biological species
occurs when extreme phenotypes are less fit than the optimal intermediate phenotype
stabilizing selection
describes the evolutionary tree that requires the fewest steps to construct from a set of observations
parsimonious tree
occurs when all members of a species have died, if speciation is the birth of a species extinction represents its death
extinction
how do environmental changes affect natural selection?
as the environments changes, organisms have to change with it in order to continue their bloodline, the phenotype that is “best” depends entirely on the time and place
theory that life’s history has been characterized by bursts of rapid evolution interrupting long periods of little change
punctuated equilibrium
recognize adaptation from an evolutionary perspective
individuals with the best adaptations to their existing environment are most likely to reproduce and pass their advantage to their offspring
when did life first form on earth and what were they?
prokaryotic cells 4.2-3.8 BYA
produces similar adaptations in organisms that do not share the same evolutionary lineage (desert plants)
convergent evolution
which period is known as the age of amphibians?
Carboniferous (354-290 MYA) (Paleozoic era)
the members of one sex choose their mates from among multiple individuals of the opposite sex (female birds choosing pretty male birds)
intersexual selection
two or more extreme phenotypes are fitter than the intermediate phenotype
disruptive selection
selective breeding strategy in which a human allows only organisms with desired traits to reproduce
artificial selection
number of individuals of one genotype, divided by the number of individuals in the population
genotype frequency
which era is known as the age of mammals?
Cenozoic era (65-.01 MYA) includes Paleogene, Neogene, and Quaternary
part of a population enters a new habitat bordering the range of the parent species
parapatric speciation
t or f: reproductive barriers can lead to three types of speciation, allopatric, parapatric, and sympatric
true
a large-scale evolutionary change
macroevolution
how did people respond to Darwin’s ideas?
some people embraced them, but others with religious domination had a clash with their beliefs and others may just have not liked the idea that humans were just another species competing for resources
calculated as the number of copies of that allele, divided by the total number of alleles in the population (the rate at which a specific allele appears within a population)
allele frequencies
who proposed a theory of uniformitarianism?
James Hutton
suggests that genetic mutations create heritable variation and that this variation is the raw material upon which natural selection acts
modern evolutionary synthesis
what are the levels of groups (taxa) used in the hierarchical system by Linnaeus
domain, kingdom, phylum, class, order, family, genus, species
inherited attributes that resemble those of the ancestor of a group
ancestral characters
a single species gives rise to multiple specialized forms in a relatively short time
adaptive radiation
held that evolution proceeds in small, incremental changes over many generations
gradualism
occurs when a populations size drops rapidly over a short period; randomly eliminates many alleles that were present in the larger ancestral population
bottleneck effect
When did the largest mass extinction occur?
at the end of the Paleozoic era, in the Permian
the time it takes for half of the atoms in a sample of a radioactive substance to decay (if an isotopes ____ is one year, 50% of the radioactive atoms in a sample with have decayed in a year, in another year, half of the remaining radioactive atoms will decay, leaving 25% and so on
half-life
- the biological species concept cannot apply to asexually reproducing organisms (bacteria, archaea, and many fungi and protists)
- it is impossible to apply the biological species definition to extinct organisms known only from fossils
- some types of organisms have the potential to interbreed in captivity, but they do not do so in nature
- reproductive isolation is not always absolute
problems with Linnaeus’s biological species definition (did not consider the role of evolutionary relationships)
reduce the fitness of a hybrid offspring if fertilization does occur
postzygotic reproductive barrier
what was the name of Darwin’s book and what impact did it have?
Darwin’s book was 490 pages and was called “On the Origin of Species by Means of Natural Selection, or Preservation of Favoured Races in the Struggle for Life, and it would form the underpinning of modern life science
t or f: fossils became abundant at the start of the Phanerozoic
true
the theory that suggests that a series of brief, violent, global upheavals such as enormous floods, volcanic eruptions, and earthquakes were responsible for most geological formations
catastrophism
t or f: natural populations often violate HW equilibrium
true
what are the three domains of life?
archaea, bacteria, and eukarya
- biological evolution explains the origin of life
- evolution is a random process
- in a changing environment, all individuals in a population simultaneously develop beneficial adaptations
misconceptions of natural selection
who was the first to openly suggest that closely related species arose from a common ancestor and were changing?
George-Louis Buffon
a phylogenetic system that defines groups based on characters that indicate shared ancestry
cladistics
- the vast majority of organisms never leave a fossil trace
- erosion (movement of earth’s continental plates) has destroyed many fossils that did form
- scientists are unlikely to ever discover the many fossils that must be buried deep in the Earth or submerged underwater
reasons why the fossil record is incomplete
what are the two HW equations?
p + q =1
p2 + 2pq + q2 = 1
a change in allele frequencies that occurs purely by chance, tends to eliminate alleles from a population
genetic drift
who was convinced of catastrophism and used his knowledge of anatomy to identify fossils and describe the similarities amongst organisms? As well as being the first to recognize the principle of superstition.
Georges-Cuvier
t or f: natural selection is an evolutionary mechanism
true
the study of the evolutionary relationship among species
phylogenetics
the theory that suggested that processes of erosion and sedimentation that act in modern times have also occurred in the past, producing profound changes in the earth over time
uniformitarianism
to or f: low genetic diversity in small populations can increase chance of extinction
true
T or F: populations evolve, not individuals alone
true
interbreeding members of the same species occupying the same region
population
which era is known as the age of reptiles?
The Mesozoic era (248-65 MYA) includes Triassic, Jurassic, and Cretaceous
phylogenetic (evolutionary) trees
phylogenies
temporal isolation (two species that share a habitat will not mate because they are active at different times or reach reproductive maturity at different times), behavioral isolation (behavioral differences may prevent two species from mating), mechanical isolation (any change in the shape of the gamete delivering or receiving structure may prevent interbreeding), gametic isolation (sperm cannot fertilize an egg cell), ecological isolation (difference in habitat preference separates two pops.)
prezygotic barrier examples
deep water trench that separated the islands of Borner + Java and Sulawesi
Wallace’s line
the small, generation-by-generation changes to a population’s gene pool
microevolution
t or f: adaptive radiation is common on islands
true
t or f: natural selection acts on existing mutation, and only heritable mutations affect evolution
true
when did homo sapiens appear
200,000 years ago
type of natural selection resulting from variation in the ability to obtain mates, and it occurs in two forms
sexual selection
t or f: natural selection eliminates poorly adapted phenotypes
true
a new species arise while living in the same physical area as its parent species
sympatric speciation
earth’s surface consists of several rigid layers, called tectonic plates, that move in response to forces acting deep within the planet
theory of plate tectonics
is the science of describing, naming, and classifying species
taxonomy
some parts of an organism’s body may appear superficially similar in structure and function but they evolved independently of one another (wings of birds and butterflies, same function but not the same materials or organization)
analogous
when a great number of species disappeared in a relatively short time
mass extinction
which era did the age of fish and amphibians occur?
the Paleozoic era
t or f: natural selection requires limited resources and genetic diversity
true
a highly unlikely situation where allele frequencies and genotype frequencies do not change from one generation to the next
Hardy-Weinberg Equilibrium
what were Lyell’s ideas about the age of Earth and fossils?
Lyell believed that the gradual changes in some organisms could be represented in successive fossil layers
the study of fossil remains or other clues to past life
paleontology
the greater the similarity between two modern species, the closer their evolutionary relationship
assumption of molecular evolution
- every genome has limited potential, imposed by its evolutionary history
- no population contains every allele needed to confront every possible change in the environment
- disasters like floods and volcanic eruptions can eliminate the best alleles combinations, simply by chance
- some harmful genetic traits are out of natural selection’s reach like Huntingtons disease
factors that limit natural selection
describes how self-replicating RNA may have been the first independent precursor to life on earth
RNA world
the members of one sex compete among themselves for access to the opposite sex (male ox beetles fight during mating season)
intrasexual selection
how are humans contributing to a 6th possible mass extinction
destroying and polluting habitats, introducing alien species that compete with the native species, and harvesting species faster than they can reproduce
the study of the distribution of species across the planet
biogeography
suggests that meteorites or comets have crashed to Earth, sending dust, soot, and other debris into the sky, blocking sunlight and triggering extinctions in a deadly chain reaction. without sunlight the plants died, the animals likewise died without good and shelter
impact theory
places a fossil into a sequence of events without assigning it a specific age
relative dating
contrast natural and artificial selection
natural selection is something that happens naturally along with changes in the environment, causing the best attributes to be further reproduced; artificial selection is when humans selectively breed other animals in order to benefit them, in nature these attributes would not have ever happened if not for human intervention
features that provide a selective advantage because they improve an organism’s ability to survive and reproduce
adaptations
a difference in appearance between males and females (one sex may be much larger or more colorful)
sexual dimorphism
what are the five assumptions of the HW Equilibrium?
- natural selection does not occur
- mutations do not occur
- the population is indefinitely large
- individuals mate at random
- individuals do not migrate into or out of the population
a group at any rank
taxon
how can cytochrome c be used to study molecular evolution
the more recent the shared ancestor with humans, the fewer the differences in the amino acid sequence for the respiratory protein cytochrome c
- few individuals may colonize a new habitat that simultaneously selects for different phenotypes, eventually leading to reproductive isolation
- a new adaptation may contribute to reproductive success in a wide variety of environments
- after a catastrophe wipes out many species, the survivors diversify as they exploit the changed environment
three ways adaptive radiation can occur
when fossils of all major phyla of animals appeared within a few million years of one another in the Cambrian seas
Cambrian Explosion
basis for comparison in a cladistics analysis that consists of comparator organisms that are not part of the group being studied
outgroup
moves alleles from one population to another (doesn’t require the movement of entire individuals [wind carrying plant seeds])
gene flow
when did mammals and flowering plants arise?
the Mesozoic
the location of earth’s continents has changed with time, due to shifting tectonic plates
continental drift
was the first investigator to give every species a two-word name (genus [broader classification] and a second word that designates the species)
Carolus Linnaeus
define evolution in terms of allele frequencies
evolution is a change in the frequency of an allele in a population
t or f: multicellularity arose independently in multiple lineages of protists and fungi
true
what do p2, 2pq, and q2 represent in HW equation?
represents the genotype frequencies of homozygous dominant (p2), heterozygous (2pq), and homozygous recessive (q2)
population, or group of populations, whose members can interbreed and produce fertile offspring
speciation
over many generations, a population’s characteristics can change by natural selection, even giving rise to new species
descent with modification
uses of the HW equilibrium
we can use the HW equations to estimate allele frequencies based on the known frequency of one genotype
any evidence of an organism from more than 10k years ago (end of Pleistocene epoch)
fossil
when did earth originate?
4.6 billion years ago
uses DNA sequences to estimate the time when multiple organisms diverged from a common ancestor
molecular clock
t or f: photosynthesis using water led to O2 accumulation on earth
true
What likely caused the Cretaceous mass extinction?
an asteroid impact near the Yucatan peninsula, photosynthesis was non-existent for 3 years
multiple alleles of a gene persist indefinitely in the population at more or less constant frequencies indefinitely (the persistence of multiple alleles in a population)
balanced polymorphism
what were Darwin’s three observations? what did he infer?
- individuals in a species are different from one another, and at least some of this variation is heritable
- essential sources such as food and space are limited in every habitat
- in every population, more offspring are born than can survive
he inferred that organisms engage in a struggle for existence, they must compete for resources; he also inferred that those individuals with the most adaptive traits would be most likely to win the competition; his last inference was that over many generations, natural selection could change a population or give rise to a new one
genes that encode proteins that regulate development (when mutated, leads to organisms with structures in the wrong places)
homoeotic genes
t or f: new species arise due to reproductive isolation because they can no longer breed and produce fertile offspring with the rest of the population
true
who renewed the argument for uniformitarianism, suggesting that natural processes are slow and steady and that Earth is much older than 6000 years? (one conclusion from his contribution is that gradual changes in some organisms could be represented in successive fossil layers
Charles Lyell
which period is known as the age of fishes?
Devonian (417-354 MYA) (Paleozoic era)
what does it mean for a trait to be selectively neutral?
they neither increase nor decrease reproductive success
what were the observations from Darwin on his journey?
heritable variations (no two individuals in a species are exactly alike, some of this variation is heritable), limited resources, and overproduction of offspring (more individuals are born that survive to reproduce)
when did eukaryotic cells arise?
1.5 BYA
when individuals with certain genotypes—those that are best suited to the environment—have greater reproductive success than other individuals
natural selection
t or f: natural selection does not have a goal
true, natural selection does not have a goal
occurs when a small group of individuals leaves its home population and establishes a new, isolated settlement individuals
founder effect
a new species forms when a geographical barrier physically separates a population into two groups that cannot interbreed, barrier may be a river, desert, glacier
allopatric speciation
example of heterozygote advantage
sickle cell disease
why are mutations the raw material for evolution?
because genes contribute to phenotypes, and natural selection acts on phenotypes
the idea that lower layers of rock (and the fossils they contain) are much older than those above them
principle of superstition
t or f: changes in regulatory DNA can affect body features
true
descent [inheritance] with modification [changes from gen. to gen.]
evolution
t or f: sexual reproduction amplifies variability in a species
true
since evolution can explain how populations become different over time, Wallace’s observation led to the prediction that the regions must have been separated for a long time; later, a deep trench was discovered that separated the island even when sea levels fell, preventing gene flow between organisms on each side
this is why marsupials of Australia are diverse and restricted to mainly Australia
results from the steady, gradual loss of species due to normal evolutionary processes
background extinction rate
choosing mates based on location, physical traits, or other factors
nonrandom mating
How did Wallace propose natural selection?
he had observed the diverse animals of South America and Southeast Asia, and his manuscript independently proposed that natural selection was the driving force of evolution
who was the taxonomic hierarchy developed by
Linnaeus
has features that are different from those found in the group’s ancestor
derived characters
examples of artificial selection
humans breed dogs to look a specific way, also selectively breeding farm animals like cows, chickens, pigs, etc
the three eras of the Phanerozoic
Paleozoic, Mesozoic, and Cenozoic
how do microevolutionary changes lead to genetic divergence
mutations, natural selection, and genetic drift are microevolutionary changes that can lead to divergence with the accumulation of enough differences in their gene pools, they can no longer produce fertile offspring
the entire collection of genes and alleles
gene pool
study of the classification, therefore, incorporates two interrelated specialties: taxonomy and phylogenetics
systematics
t or f: genetic drift is more likely to affect small populations
true
what lines of evidence are used to form phylogenetic trees?
anatomical features of fossils and existing organisms, also behaviors, physiological adaptations, and molecular sequences
(occurs when the number of sets of chromosomes increases) sometimes arises when gametes from two different species fuse, and can also occur when meiosis fails [rare in animals, common in plants]
polyploidy
what are the lines of evidence of evolution?
fossils and biogeographical studies provided the original evidence but comparisons of embryonic development and anatomical structures provided additional supporting data
large-scale evolutionary events, such as the appearance of a new species
macroevolution
prevent the formation of a zygote
prezygotic reproductive barrier
what were Lamarck’s ideas about the origin of the species?
organisms that used one part of their body repeatedly would increase their abilities, conversely, disuse would weaken an organ until it disappeared
how does natural selection apply to the diversity of finches on the islands?
natural selection applies to the finches because on different islands there are different environments in which some attributes may be more qualified than others to live on that island which is why the finches had different beak shapes based on where they were on the island and what kind of food they could consume
similar in structure or position because of common ancestry (homologous forelimbs in humans, lions, and birds)
homologous
one extreme phenotype is fittest, and the environment selects against others
directional selection
occurs when an individual with two different alleles for a gene (heterozygotes) has greater fitness than those whose two alleles are identical (homozygotes)
heterozygote advantage
proposes that mitochondria and chloroplasts originated as free-living bacteria that began living inside other cells
endosymbiotic theory
a treelike diagram built using shared derived characters
cladogram
refers to an organisms genetic contribution to the next generation
fitness
t or f: microevolution can lead to macroevolution
true
how did thomas malthus inspire Darwin’s work?
Malthus wrote an essay that stated that food availability, disease, and war limit the size of the human population, which made Darwin believe the same could happen to other organisms
what do p and q represent in HW equation?
represent the allele frequencies (p = dominant; q = recessive)
evidence of the impact theory
iridium on earth, rare on earth but common in meteorites
who proposed the first scientifically testable evolutionary theory? reasoning that organisms that used one part of their body repeatedly would increase their abilities, conversely, disuse would weaken an organ until it disappeared
Jean Baptiste de Lamarck
t or f: development reveals homology
true
t or f: fitness depends on reproduction
true
