ch.6 evolution, ecology Flashcards
evolution
changes in populations, species or groups; changes in allele (traits) frequencies in populations over time
microevolution
the changes in allele frequencies that occur over time within a population due to mutation, selection, gene flow, gene drift, and nonrandom mating
macroevolution
the patterns of changes in groups of related species over broad periods of geologic time. patterns determine phylogeny (evolutionary relationships among species and groups of species). these patterns can be used to establish a phylogenetic tree
Lamarck Theory: use and disuse
body parts can develop with increased usage and unused parts are weakened
Lamarck Theory: inheritance of acquired characteristics
body features acquired during one’s lifetime can be passed down to offspring.
this is incorrect, since only changes in genetic material of cells can be passed down to offspring
natural transformation of species
organisms produce offspring with changes, transforming each consecutive generation to be slightly more complex. Lamarck did not believe in extinction or the splitting of creating more species. This is an incorrect idea!
natural selection
survival of the fittest without any luck. allele frequencies increase or decrease in order to adapt to the environment
Neo-Darwinism
synthetic theory of evolution that combines Darwin’s theory with the influence of genetics that Darwin was unaware of to propose mechanisms responsible for evolutionary patterns
descent with modification
coined by Darwin, this occurs via natural selection. over time and generations, traits providing reproductive advantage becomes more common within the populaion
paleontology
fossils reveal prehistoric existence of extinct species, and are often found in sediment layers. deepest fossils represent the oldest specimens. large, rapid changes produce new species
fossil types
actual remains, petrification, imprints, molds, and casts
biogeography
the geography that describes the distribution of species. unrelated species in different regions of the world look alike when found in a similar environment. the supercontinent Pangea slowly broke apart to 7 continents due to continental drift
embryology
similar stages of development among related species establishes evolutionary relationships. gill slits and tails are found in fish, chickens, pigs, and human embryos
ontogeny
the development of an organism
phylogeny
the evolutionary development and diversification of a species
homologous structures
body parts that resemble one another between different species that descended from a common ancestor. e.g., bat forelimbs vs. bird forelimbs
analogous structures
body parts that resemble one another between different species that evolved independently. they have similar structures as adaptations to similar environments. these structures are also called homoplasies. e.g., bat wings vs. bee wings
molecular biology
this field examines nucleotide and amino acid sequences of DNA and proteins from different species. more than 98% of nucleotide sequences in humans and chimpanzees are identical. amino acids in the protein cytochrome c are often compared
comparative biochemistry
organisms with a common ancestor mean they have common biochemical pathways
stabilizing selection
the bell curve favors an intermediate, like how the average height in humans is in the middle
directional selection
the favoring of traits that is at one extreme of the range. traits at opposite extremes are selected against
industrial selection
the selection of dark-colored, melanic, varieties in various species of moths, like the peppered moth, as a result of industrial pollution. this is a specific type of directional selection
disruptive selection
this selection occurs when the environment favors extreme or unusual traits while selecting against common traits. for example, a certain environment may favor short and tall heights while the average height is selected against
sexual selection
the differential mating of males or females in a population
intersexual selection
females choose superior males, which increases the fitness of the offspring. because females invest more energy into their offspring, they want to maximize the quality of their offspring by picking fit males
intrasexual selection
when males compete and fight with other males for better mating opportunities. males increase fitness of offspring by maximizing quantity. intrasexual selection favors traits like musculature, horns, large stature etc.
sexual dimorphism
the differences in appearance of males and females, which is a form of disruptive selection. this occurs because female choice leads to traits and behaviors in males that are favorable to females. male traits like colorful plumage or elaborate mating behavior will be selected for by females
artificial selection
this is a form of directional selection carried out by humans when they breed favorable traits, and it not natural selection
mutation
new alleles could be introduced to the population with genetic mutations
sexual reproduction
genetic recombination such as crossing over, independent assortment, and random joining of gametes can occur during sexual reproduction
diploidy
diploid organisms have two copies of each chromosome. in heterozygous conditions, the recessive allele is stored for later generations, and thus more variations are maintained in the gene pool
outbreeding
mating with unrelated partners results in mixing of different alleles and creating new allele combinations
hybrid vigor (heterosis)
the superior quality of offspring resulting from crosses between two different inbred strains, species, or varieties of organisms. hybrid superior quality results from reducing deleterious recessive homozygous conditions and increasing heterozygous advantage
frequency-dependent selection (minority advantage)
occurs when least common phenotypes have a selective advantage. common phenotypes are selected against. rare phenotypes will increase in frequency and will then be selected against, repeating the cycle. for example, predators use search images of common phenotypes and find prey, allowing prey with rare phenotypes to escape. the rare prey phenotype eventually becomes common, and then the cycle repeats
neutral variation
these are variations that are passed down without any selective value, such as fingerprints in humans
geographic variation
variation of a species is dependent on climate or geographic conditions. a graded variation of a phenotype due to this is known as a cline. variation from north to south environments is a north-south cline
natural selection
the increase and decrease of allele frequencies due to adaptations to the environment
gene flow
the introduction and removal of alleles from the population when individuals leave (emigration) or enter the population
genetic drift
the random increase and decrease of an allele by chance. genetic drift has a larger effect on small populations
founder effect
when a small group of individuals migrate to a new location, the gene pool of the small group will be less than the original population. after successive generations, the genetic makeup will be unique from the original population
bottleneck effect
occurs when the population undergoes a dramatic decrease in size due to natural catastrophes or other events. the population is now vulnerable to genetic drift, and the gene pool is much smaller
nonrandom mating
individuals choose mates based upon their particular traits
inbreeding - individuals mate with relatives, this changes genotype proportions but not allele frequency
sexual selection - females choose males based on superior traits
Hardy-Weinberg equation
p2 + 2pq + q2 = 1
p+q=1
requirements to be in Hardy-Weinberg equilibrium
- no mutations
- no natural selection - the environment is not impacting allele frequencies, so traits are neutral
- no gene flow
- large populations - this decreases the effects of genetic drift
- random mating
speciation
the formation of new species. when gene flow ceases, or is interrupted, between two sections of a population, speciation begins
species
a group of individuals capable of interbreeding
allopatric speciation
this speciation occurs when the population is divided by a geographic barrier. interbreeding between two resulting populations is prevented as a result. the gene frequencies in the population can now diverge due to natural selection, mutation, and genetic drift. if the gene pool sufficiently diverges, the separated populations will not interbreed when the barrier is removed. if they cannot interbreed, that means a new species has formed
dispersal
the group is isolated by being physically removed from the original location of the larger group
vicariance
the group is isolated by a geographic barrier but is in the same overall location of the larger group
sympatric speciation
this is the formation of new species without the presence of geographic barriers
balanced polymorphism
natural selection due to polymorphism
ex: only some insects can camouflage, the ones that cannot will be eaten. only insects with the advanatageous color will mate bc they survive, and are now isolated from other subpopulations
polyploidy
possessing more than the normal two sets of chromosomes, such as 3n or 4n. this can lead to reproductive isolation, such as in plants
autopolyploidy
when an organism has more than two sets of chromosomes, both of which are from the same parental species
allopolyploidy
when an organism has more than two sets of chromosomes, but they come from different species
hybridization
two different closely related species mate and produce a hybrid along a geographic boundary called a hybrid zone
can result in more genetic variation. this means the hybrid can live beyond the range of either parents
reinforcement
hybrids are less fit than either purebred species. the species continue to diverge until hybridization can no longer occur
fusion
reproductive barriers weaken until the hybrid and purebred species become one
stability
fit hybrids continue to be produced
adaptive radiation
the rapid evolution of many species from a single ancestor. this occurs when an ancestral species is introduced to an area where diverse geographic and ecological conditions are available for colonization
prezygotic isolation
prevents fertilization before mating is attempted, and so a zygote is not formed
habitat isolation
species do not encounter each other because they live in different habitats, even if they live in the same geographical area
temporal isolation
species reproduce at different seasons/times
behavioral isolation
some species will not reproduce with each other if they do not perform the correct courtship rituals
mechanical isolation
occurs when male and female genitalia are not compatible
gametic isolation
male and female gametes do not recognize each other. the male gametes also may not survive in the environment of the female gametes
postzygotic isolation
if a zygote does form
hybrid inviability
the zygote fails to develop properly and dies before reaching reproductive maturity
hybrid sterility
hybrids become functional adults but cannot reproduce
hybrid breakdown
hybrids produce offspring that have reduced viability/fertility. the hybrid’s children cannot reproduce
divergent evolution
this type of evolution occurs when two or more species that originated from a common ancestor become increasingly different over time as a result of speciation
convergent evolution
occurs when two unrelated species evolve to share more similar traits due to adapting to a similar environment (analogous traits)
parallel evolution
occurs when two unrelated species make similar evolutionary changes after their divergence from a common ancestor
coevolution
occurs between two species. each causes the other one to evolve, which results in the evolution of both species. an example of this is the coevolution of predators and prey, where the evolution of a more effective predator will cause the prey to evolve better ways to defend itself
phyletic gradualism
this theory says that evolution occurs by the gradual accumulation of small changes. however, this is unlikely to be valid because intermediate stages of evolution are missing in the fossil record
punctuated equilibrium
this theory says that evolutionary history consists of geologically long periods of stasis (stability) with little or no evolution follows by geologically short periods of rapid evolution. absence of fossils revealing intermediate stages of evolution is considered data that confirms rapid evolutionary events
Oparin & Haldane
these scientists proposed the organic soup theory. they said that if there was O2 in the primordial atmosphere, no organic molecules would have formed because oxygen is very reactive. Oparin’s hypothesis was that the early Earth’s environment was reducing which provides the chemical requirements to produce complex molecules from simple building blocks. an oxidizing environment would have broken the complex molecules apart
Stanley Miller
testes Oparin’s theory and produced organic molecules. Miller & Urey sealed ammonia, water, methane, and hydrogen in a flask and simulated lightning; they created a simulated environment of the primordial Earth. the experiement produced several organic molecules, amino acids, and starting materials. however, no nucleic acids were made!
vestigial structures
appear ti be useless but had ancestral function. for example, humans have vestigial appendixes and tails, horses have vestigial splints, and pythons have vestigial reduced leg bones
Mullerian mimicry
two or more harmful species that are not closely related but share one or more common predators, have come to mimic each other’s warning signals
Batesian mimicry
this is slightly different from Mullerian mimicry in that a harmless species has evolved to imitate the warning signals of a harmful species directed at a common predator
gene pool
all the alleles for any given trait in the population
parapatric speciation
occurs without a geographic barrier, so the population is continuous, but it still does not mate randomly. individuals more likely to mate with geographic neighbors than with an individual farther out, so divergence may happen due to reduced gene flow and because of varying selection pressures across the population’s range. a population may occupy different niches that are adjacent and not isolated, so parapatric speciation could occur
peripatric speciation
similar to allopatric speciation in that a population is isolated and prevented from exchanging genes from the “main” one, but one of the populations is much smaller than the other, so it is subject to accelerated genetic drift along with differing selection pressures
anagenesis/phyletic evolution
the gradual evolution of a species without any branching; it is a straight path of evolution
cladistics
a method of classification according to the proportion of measurable characteristics held in common between two organisms. the more characteristics they share, the more recently they diverged from common ancestor
clade
a group of species that include a common ancestor and all of its descendants. a clade is also known as a monophylum
sere
a particular stage of an ecosystem
mold
an organic matter that leaves an impression in rocks or in inorganic matter. later, the organic matter decays and leaves a negative impression
cast
a type of fossil formed when mold is filled in
deme
a small local population of the same species that regularly interbreed. for example, all the beavers along a specific portion of a river
autotrophic anaerobes
chemosynthetic bacteria
autotrophic aerobes
green plants and photoplankton
heterotrophic anaerobes
yeast
heterotrophic aerobes
amoebas, earthworms, and humans
symbiosis
a relationship between two species that can be:
1. mutualistic - beneficial to both species
2. commensalism - beneficial to one species and neutral to the other
3. parasitism - beneficial to one species but detrimental to the other
synapomorphies
shared traits derived from an evolutionary ancestor common to all members of a group
analogous traits
similar characteristics resulting from convergent evolution, therefore they are not derived from a common ancestor
law of parsimony
this is also known as Occam’s Razor, which states that the simplest explanation is most likely correct. phylogenetic trees are constructed using the Law of Parsimony. the fewest number of changes with respect to synapomorphies is likely the most correct representation of reality
monophyletic
the ancestral species and all its descendants
paraphyletic
the ancestral species and some but not all descendants
