BIO 130 Flashcards
Theory
An explanation for a broad class of phenomena that is supported by a wide body of evidence. A theory serves as a framework for the development of new hypotheses.
Evolution
(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection, genetic drift, gene flow, and mutation. (2) Any change in the genetic characteristic of a population over time, especially a change in allele frequencies.
Population Thinking
A way of thinking that emphasizes the importance of variation among individuals in a population; the opposite of typological thinking, which ignores variation or considers it unimportant.
Descent with modification
The phrase used by Darwin to describe how species that lived in the past are the ancestors of species existing today, and that species change through time.
Extant Species
a species that is living today
Transitional feature
A trait that is intermediate between a trait observed in ancestral species and the homologous trait observed in derived species
Vestigial Trait
A reduced or incompletely developed structure that has no function, or reduced function, but is nearly similar to functioning organs or structures in ancestral or closely related species.
Homology
Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity are said to be homologous.
Genetic Homology
Similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor
Developmental homology
A similarity in embryonic form or developmental processes that is due to inheritance from a common ancestor
Structural Homology
Similarities in adult organismal structures that are due to inheritance from a common ancestor
Morphology
The overall shape and appearance of an organism and its component parts
Artificial Selection
Deliberative manipulation by humans, as in animals and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits to reproduce
Natural Selection
The process by which individual with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution. The only evolutionary process that produces adaptation.
Fitness
The ability of an individual to produce viable offspring relative to others of the same species
Acclimatization
A change in an individuals phenotype that occurs in response to a change in natural environmental conditions.
Acclimation
A change in a study organisms phenotype that occurs in response to laboratory conditions
Fitness trade-off
In evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously.
Genetic Correlation
A type of evolutionary constraint in which selection on one trait causes a change I another trait as well; may occur when the same gene affect both traits.
Population genetics
The branch of evolutionary biology responsible for investigating processes that cause changes in allele and genotype frequencies in populations.
Natural Selection
Increases the frequency of certain alleles-the ones that contribute to reproductive success in a particular environment
Genetic Drift
Causes allele frequencies to change randomly. In some cases, drift may cause alleles that decrease fitness to increase in frequency
Gene flow
Occurs when individuals leave one population, join another, and breed. Allele frequencies may change when gene flow occurs, beaus arriving individuals introduce alleles to their new population and departing individuals remove alleles from their old population
Mutation
Modifies allele frequencies by continually introducing new alleles. The alleles created by mutation may be beneficial, deleterious(detrimental), or neutral in their effects on fitness.
Gene pool
All the alleles of all the genes in a certain population
Hardy-Weinberg Principle
A principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes and nonrandom mating
Hardy-Weinberg Equilibrium
A state of agreement between observed allele frequencies in a population and allele frequencies predicted by the Hardy-Weinberg principle.
Random Mating
The model assumes that gates from the gene pool combine a random. Individuals are not allowed to choose a mate.
No natural Selection
The model assumes that all members f the parental generation survive and contribute equal numbers of gametes to the gene pool, no matter what their genotype.
No genetic Drift
The model assumes that alleles are picked in their exact frequencies p and q, and nit at different frequencies caused by chance-that is, the model behaves as though the population is infinitely large.
No gene flow
The model assumed that no new alleles are added by immigration or lost through emigration. As a result, all of the alleles in the offspring population come from the original population’s gene pool.
No mutation
The model assumes that no new alleles are introduced into the gene pool.
Inbreeding Depression
The decline ion average fitness that takes place when homozygosity increases and heterozygosity decreases in a population due to inbreeding; results from the exposure if deleterious recessive alleles to selection.
Sexual Selection
A type of natural selection that favors individuals with traits that increase their ability to obtain mates or choose good mates. Compare with ecological selection.
Directional Selection
A mode of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population. Compare with disruptive selection and stabilizing selection.
Purifying Selection
Selection that lowers the frequency of, or even eliminates, deleterious alleles.
Stabilizing Selection
A mode of natural selection that favors phenotypes near the middles of the range of phenotypic variation. Reduces overall genetic variation in a population. Compare with disruptive selection and directional selection.
Disruptive Selection
A mode of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Increases overall genetic variation in a population. Compare with stabilizing selection and directional selection.
Purifying Selection
Selection that lowers the frequency of, or even eliminates, deleterious alleles.
Stabilizing Selection
A mode of natural selection that favors phenotype near the middle of the range of phenotypic variation. Reduces overall genetic variation in a population. Compare with disruptive selection and directional selection.
Balancing Selection
A mode of natural selection in which no single allele is favored over time and across locations, on average. An overall balance of fitness and frequency is maintained among alleles.
Heterozygote Advantage
A pattern of natural selection that favors heterozygous individuals compared with homozygous. Tends to maintain genetic variation in a population and thus is a form of balancing selection.
Frequency-dependent Selection
A pattern of selection in which certain alleles are favored only when they are rare; a form of balancing selection.
Inter Sexual Selection
A type of sexual selection in which an individual of one sex chooses a particular individual of the other sec for mating. (Often the mate that offers more chooses)
Intra Sexual Selection
A type of sexual selection driven by competition among members of one sex(usually male-male) for an opportunity to mate.
Sexual Dimorphism
Any trait that differs between males and females
Sexual Polymorphism
Any trait that occurs in two or more forms among females and males in a population.
Genetic Drift
Any change in allele frequencies due to chance. Causes allele frequencies to drift up an down randomly over time, and eventually can lead to the fixation or loss of alleles.
Sampling error
The selection of a non representative sample from some larger population, due to chance; not a type of mistake in measurement.
Genetic Bottleneck
A reaction in the diversity of alleles in a population resulting from a sudden decrease in the size of that population due to a random event
Gene Flow
The movement of alleles between populations; occurs when individuals leave one population, Join another, and breed.
Speciation
The evolutionary of two or more distinct species from a single ancestral species
Gene Isolation
occurs when some sort of barrier to gene flow isolates two populations within a species. Recall that gene flow makes allele frequencies more similar among populations-so the absence of gene flow means that alleles are no longer exchange.
Genetic Divergence
Occurs when mutation, natural selection, and genetic drift occur in each of the isolated populations- meaning that the populations begin to evolve independently of each other. If isolated populations diverge sufficiently, distinct species form.
Biological Species Concept
The definition of species as a population or group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species.
Prezygotic isolation
Reproductive isolation resulting from any combination of several mechanisms that prevent individuals of two different species from mating.
Postzygotic isolation
Reproductive isolation resulting from mechanisms that operate after mating of individuals of two different species occurs. The most common mechanisms are the death of hybrid embryos or reduced fitness of hybrids.
Morphospecies concept
The definition of species as a population that have measurably different anatomical features from other groups. Also called morphological species concept. Compare with biological species concept and phylogenetic species concept.
Polymorphic species
A species that has two or more distinct phenotypes in the same interbreeding population at the same time.
Cryptic Species
A species that cannot be distinguished from similar species by easily identifiable morphological traits.
Phylogenetic species concept
The definition of a species as the smallest monophyletic group in a phylogenetic tree. Compare with biological species concept and morphospecies concept.
Monophyletic group
An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage. Compare with paraphyletic group and polyphyletic group.
Clade
An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage. Compare with paraphyletic group and polyphyletic group.
Lineage
An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage. Compare with paraphyletic group and polyphyletic group.
Synapomorphy
A shared, derived trait found in two or more taxa that is present in the most recent common ancestor but is mission in more distant ancestors. Useful for inferring evolutionary relationships.
Systematics
The sub discipline of biology that characterizes and classifies the relationship among all organisms on earth.
Taxonomy
The branch of biology concerned with describing, naming and classifying groups of organisms.
Polymorphic Species
A species that has two or more distinct phenotypes in the same inbreeding population at the same time.
Cryptic Species
A species that cannot be distinguished from similar species by early identifiable morphological traits.
Allopatry
Condition in which two or more populations live in different geographic area.
Allopatric Specieation
Speciation that occurs when populations of the same species become geographically isolated, often due to dispersal or vicariance.
Dispersal
The movement of individuals from their place of origin to the location where they live and breed as adults.
Vicariance
The physical splitting of a population into smaller, isolated populations by a geographical barrier.
Sympatry
Condition in which two or more populations live in the same geographical area, or close enough to permit interbreeding.
Sympatric Speciation
The divergence of populations living within the same geographical area into different species as the result of their genetic isolation.
Niche
The range of resources that a species can use and the range of conditions that it can tolerate. More broadly, the role that a species plays in its ecosystem.
Autopolyploid
The state of having more than two full sets of chromosomes due to a mutation that doubled the chromosome number. All the chromosomes come from the same species.
Allopolyploid
The state of having more than two full sets of chromosomes due to the hybridization between species.
Reinforcement
In evolutionary biology, the natural selection for traits that prevent interbreeding between recently diverged species.
Hybrid Zone
A geographic area where interbreeding occurs between two species, sometimes producing fertile hybrid offspring.
Phylogeny
The evolutionary history of a group of organisms.
Phylogenetic tree
A branching diagram that depicts the evolutionary relationship among species or other taxa.
Systematics
The sub discipline of biology that characterizes and classifies the relationship among all organisms on earth.
Taxa
Any named group of organisms at any level of a classification system.
Branch
A line representing a species or other taxon through time.
Root
The most ancestral branch in the tree
Tip
Endpoint of a branch; represents a living or extinct species or other taxon.
Outgroup
A taxon that diverged before the taxa that are the focus of the study; helps to root the tree
Node(fork)
A point within the tree where a branch splits into two or more branches; the node represents the most recent common ancestor of the descendant groups.
Polytomy
A node that depicts an ancestral branch dividing into three or more descendant branches; usually indicates that insufficient data were available to resolve which taxa are more closely related.
Sister Groups
Two lineages that are each other’s closest relatives, represent by two branches emerging from a node in a phylogenetic tree.
Character
Any heritable genetic, morphological, physiological, developmental, or behavioral characteristic of an organism to be studied.
Trait
Any observable characteristic at any level of observation of an individual
Ancestral Trait
A trait found in the ancestors of a particular group
Derived trait
A trait that is a modified form of an ancestral trait, found in a descendant.
Synapomorphy
A shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors. Useful for inferring evolutionary relationships.
Homology
Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity are said to be homologous.
Homoplasy
Similarity among organisms of different species due to reasons other than common ancestry, such as convergent evolution.
Parsimony
The principle that the most likely explanation of a phenomenon is the most economical or simplest. When applies to comparison of alternative phylogenetic trees, it suggests that the one requiring the fewest character changes is most likely.
Bioinformatic
A discipline at the intersection of biology, computer science, and statistics concerned with the storage, analysis, and presentation of biological data, particularly with nucleotide and Aino acids sequences in the field of genomics.
Convergent Evolution
The independent evolution of similar traits in different species due to adaptation to similar environmental conditions and a similar way of life.
Precambrian
The interval between the formation of the Earth, about 4.6 billion years ago, and the appearance of most animal groups about 541 million years ago. Unicellular organisms were dominant for most of this era, and oxygen was virtually absent for the first 2 billion years.
