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88 Cards in this Set

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  • Back
What is evolution?
The process of change and adaptation leading to the development of new life forms and genetic diversity
What did jean Lamarck formulate?
The concept of use and disuse
What did that say?
Organs that are used extensively develop, while organs that are not used atrophy
What did Lamarck theorize about newer species?
He said that newer, more complex species arise from older and simpler species through the accumulation and modification of acquired characteristics
What are the basic agents leading to evolutionary change outlined by Darwin?
He said organisms produce offspring, very few of which survive to reproductive maturity.
What did he say about chance variations?
He said there are chance variations between individuals in any given population, some of which are inheritable.
What do variations that five the organism a slight advantage do?
They allow it to survive better, and they are called favorable variations
What does this imply about individuals who inherit favorable variations?
He said they are likely to live longer and produce more offspring than others
What is this process referred to as?
Natural selection
What does natural selection gradually lead to?
It gradually leads to variations that differentiate organisms into groups and ultimately into distinct species
What is fitness?
It is measured in terms of reproductive success and the relative genetic contribution of an individual to the future of the population
What is natural selection the driving force behind?
What is differential reproduction?
Individuals with favorable genes produce more offspring
What does this result in?
After many generations, these favorable genes have become pervasive in the gene pool
What is the gene pool?
It consists of all of the genes of all individuals in a population at a given time
What is the model of punctuated equilibrium?
It was contended that evolutionary changes occur in spurts
What does this contrast?
It contrast Dawin’s model, that proposes that evolutionary changes accumulate gradually and evenly over time
What is paleontology?
It is the study of the fossil record
What is biogeography?
It refers to the distribution of life forms throughout the globe
What are homologous structures?
They are similar in structure and share a common evolutionary origin
What is a classic example of homologous structures?
The forelimbs of mammals
What are analogous structures?
They contrast homologous structures in that they share a functional similarity but arose from different evolutionary origins
What is an example of this?
The wings of insects and birds are both adaptations for flight, but they evolved from separate lines of descent
What are vestigial structures?
They are remnants of organs that have lost their ancestral functions, and are evidence of evolutionary forces at work
What are examples of this?
Vestiges of limb bones in the adult python, and the appendix and vestiges of the tail bone (coccyx) in man
What is comparative embryology?
It studies the stages of embryological development in closely related organisms
What is the Hardy-Weinberg Equilibrium?
It states that evolution can be viewed as a result of changing gene frequencies within a population
What is gene frequency?
It is the relative frequency of a particular allele
What happens when the gene frequencies of a population are not changing?
The gene pool is stable, and thus the population does not evolve
What is this contingent upon?
This is true only in ideal situations where some conditions are met
What are the five conditions?
Large population size. There are no mutations. Mating between individuals is random. There is no net migration of individuals into or out of a population. The genes in the population are all equally successful at reproducing
What occurs under these conditions?
Certain equilibrium will exist between all of the genes in the gene pool, which is described by the Hardy Weinberg equation
What is the equation?
For a gene locus with only two alleles, T and t, p = the frequency of allele T, and q = the frequency of allele t
By definition this means what?
For a given gene locus, p + q = 1, since the combined frequencies of the alleles must total 100%
Thus, the actual equation is?
p2 + 2pq + q2 = 1. Where p2 = frequency of TT. 2pq = frequency of Tt. q2 = frequency of tt
Do the above conditions actually exist in nature?
What re the agents of micro evolutionary change?
Natural selection, mutation, assertive mating, genetic drift, and gene flow
When does genetic drift tend to be more pronounced?
In small populations
What is this referred to as?
The founder effect
What is assertive mating?
If mates are not randomly chosen, but rather selected according to criteria such as phenotype and proximity, the relative genotype ratios will be affected
What are the three different modes of natural selection?
Stabilizing selection, directional selection, and disruptive selection
What is stabilizing selection?
It maintains a well-adapted uniform character in a population by eliminating deviations from the norm
What does this process reduce?
The frequency of extreme phenotypes, thereby reducing variation
What is an example of this?
Stabilizing selection maintains human birth weights within a very narrow range
What is directional selection?
It produces an adaptive change over time, with an increase in the proportion of individuals with an extreme phenotype
When does this occur?
When organisms must adapt to a changing environment
What is an example of this?
The emergence of the DDT-resistant mosquito
How did this work?
The introduction of DDT produced a selectional advantage for those mosquitoes possessing the mutant gene for DDT resistance
What occurred after a period of time because of this?
The population of mosquitoes all possessed the gene for DDT resistance
What is disruptive selection?
It favors variants of both phenotypic extremes over the intermediates
What does this lead to?
The existence of two or more phenotypic forms within a population
What is this known as?
What is altruistic behavior?
It is behavior that benefits one individual at the expense of another
What is an example of this?
In bee societies in which worker bees are sterile but labor for the benefit of the hive
What is group selection?
It is the now-discredited hypothesis that certain individuals within a population inherit a gene for not reproducing, thus controlling population size at an advantageous level
Why is this hypothesis flawed?
Because such a gene could not be passed on by its nonreproducing carriers
What did this lead to the development of?
The theory of kin selection, which holds that natural selection, can lead to behavior that does not improve survival of an individual but does improve the survival of his near kin
What is inclusive fitness?
It describes fitness as the number of an individual’s alleles that are inherited by the next generation
What is speciation?
The evolution of a new species, which are groups of individuals who can interbreed freely with each other, but not with members of other species
What is genetic isolation?
It often results from the geographic isolation of a population into two groups
What does different selection pressures do?
They act upon the gene pools of each group, causing them to evolve independently
What happens eventually?
If the isolating mechanisms persist, the populations will become sufficiently different from each other as to become reproductively isolated
What are they considered then?
A distinct species
What are the two types of mechanisms called?
Prezygotic mechanisms or postzygotic mechanisms
What are prezygotic isolating mechanisms?
Temporal isolation, ecological isolation, and behavioral isolation
What is temporal isolation?
It is when two species may breed during different seasons, or during different times of the day, thus preventing interbreeding
What is ecological isolation?
It is when two species live in the same territory but in different habitats that rarely meet, and therefore, rarely mate
What is behavioral isolation?
It is when members of two species are not sexually attracted to each other due to differences in such things as pheromones or courtship displays
What is reproductive isolation?
It is when the genitalia of two species are incompatible
What about gametic isolation?
It is when intercourse can occur, but fertilization cannot
What are some postzygotic isolating mechanisms?
Hybrid inviability, hybrid sterility, and hybrid breakdown
What is hybrid inviability?
It is when genetic incompatibilities between two species abort hybrid zygote development, even if fertilization does occur
What is hybrid sterility?
It is when the offspring are sterile
What is hybrid breakdown?
It is when first-generation hybrids are viable and fertile, but second generation hybrid offspring are inviable and or infertile
What is adaptive radiation?
It is the emergence of a number of lineages from a single ancestral species
What is a niche?
A distinct lifestyle
What are patterns of evolution?
Convergent evolution, divergent evolution, and parallel evolution
What is convergent evolution?
It refers to the independent development of similar characteristics in two or more lineages not sharing a recent common ancestor
What is an example of this?
Fish and dolphins have come to resemble one another physically, although they belong to different classes of vertebrates. They evolved certain similar features in adapting to the conditions of aquatic life
What is divergent evolution?
It refers to the independent development of dissimilar characteristics in two or more lineages sharing common ancestry
What is an example of this?
Seals and cats are both mammals belonging to the order Carnivora, yet differ markedly in general appearance
What is parallel evolution?
It refers to the process whereby related species evolve in similar ways for long periods of time in response to analogous environmental selection pressures
When did the earliest evidence of primitive prokaryotic life appear?
3.5 billion years ago
What are microspheres?
They are abiotically produced polymers in an aqueous solution that spontaneously assemble into tiny proteinaceous droplets
What do they do?
They have a selectively permeable membrane that separates them from their surroundings and maintains an independent internal chemical environment
What are colloidal droplets called?
What are they capable of?
They are capable of carrying out enzymatic activity within their membrane if enzymes and substrate are present
Are they living cells?