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exam 1 study guide
| Question | Answer |
|---|---|
| Evolution | Descent with modification; the process by which species accumulate differences from their ancestors as they adapt to different environments over time; also a change in the genetic composition of a population from generation to generation. |
| Fossils | Preserved remnants or impressions of organisms that lived in the past. |
| Adaptation | An inherited characteristic that enhances an organism's survival and reproduction in a specific environment. |
| Natural Selection | A process in which individuals with certain inherited traits tend to survive and reproduce at higher rates because of those traits. |
| Artificial Selection | A process in which humans select and breed individuals that have desired traits. |
| Homology | Similarity in characteristics resulting from shared ancestry. |
| Homologous Structures | Structures in different species that are similar because of common ancestry; they may or may not have similar functions. |
| Convergent Evolution | Evolution of similar features in independent evolutionary lineages. |
| Analogous | Characteristics that are similar because of convergent evolution, not homology. |
| Biogeography | The study of the geographic distribution of species. |
| Darwin's Two Observations | Individuals in a population vary in their traits, and organisms tend to produce more offspring than the environment can support. |
| Darwin's Two Inferences | Individuals with advantageous inherited traits are more likely to survive and reproduce, and favorable traits become more common over generations. |
| Three Key Features of Natural Selection | Variation exists among individuals; variation is heritable; individuals with certain inherited traits leave more offspring than others. |
| Phylogeny | The evolutionary history of a species or group of related species. |
| Taxon | A named taxonomic unit at any level of classification. |
| Phylogenetic Tree | A branching diagram representing a hypothesis about the evolutionary history of a group of organisms. |
| Branch Point | A point on a phylogenetic tree representing the divergence of two or more taxa from a common ancestor. |
| Evolutionary Lineage | The sequence of ancestral organisms leading to a particular taxon; represented by a branch on a phylogenetic tree. |
| Sister Taxa | Groups that share an immediate common ancestor and are each other's closest relatives. |
| Rooted | A phylogenetic tree containing a branch point representing the most recent common ancestor of all taxa in the tree. |
| Basal Taxon | A taxon whose evolutionary lineage diverged early in the history of a specified group. |
| Shared Ancestral Character | A character shared by members of a clade that originated in an ancestor outside that clade. |
| Shared Derived Character | An evolutionary novelty unique to a particular clade. |
| Outgroup | A species or group that diverged before the lineage being studied and is closely related to the study group. |
| Ingroup | The species or group whose evolutionary relationships are being examined. |
| Maximum Parsimony | When multiple explanations are possible, first investigate the simplest explanation consistent with the facts. |
| Clade | A group containing an ancestral species and all of its descendants. |
| Monophyletic | A group consisting of a common ancestor and all of its descendants. |
| Paraphyletic | A group consisting of a common ancestor and some, but not all, of its descendants. |
| Polyphyletic | A group containing distantly related organisms but not their most recent common ancestor. |
| Molecular Clock | A method for estimating the time required for a given amount of evolutionary change based on genome regions that evolve at constant rates. |
| Horizontal Gene Transfer | Transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and possibly organismal fusions. |
| Microevolution | Evolutionary change below the species level; change in allele frequencies in a population over generations. |
| Genetic Variation | Differences among individuals in the composition of their genes or other DNA sequences. |
| Phenotypic Plasticity | Ability of an individual genotype to produce different phenotypes when exposed to different environmental conditions. |
| Neutral Variation | Genetic variation that provides neither a selective advantage nor disadvantage. |
| Adaptive Evolution | A process in which traits that enhance survival or reproduction tend to increase in frequency in a population over time. |
| Genetic Drift | Chance events causing unpredictable fluctuations in allele frequencies from one generation to the next; effects are strongest in small populations. |
| Founder Effect | Genetic drift occurring when a few individuals become isolated and form a new population whose gene pool is not representative of the original population. |
| Bottleneck Effect | Genetic drift occurring when population size is reduced, leaving a population that is typically no longer genetically representative of the original. |
| Gene Flow | Transfer of alleles from one population to another through movement of fertile individuals or their gametes. |
| Relative Fitness | The contribution an individual makes to the next generation's gene pool relative to other individuals. |
| Directional Selection | Selection in which individuals at one end of the phenotypic range survive or reproduce more successfully. |
| Disruptive Selection | Selection in which individuals at both extremes survive or reproduce more successfully than individuals with intermediate phenotypes. |
| Balancing Selection | Natural selection that maintains two or more phenotypic forms in a population. |
| Heterozygote Advantage | Greater reproductive success of heterozygous individuals compared with homozygotes; tends to preserve variation. |
| Gene Pool | The aggregate of all copies of every type of allele at all loci in every individual in a population. |
| Population | A group of individuals of the same species living in the same area and interbreeding to produce fertile offspring. |
| Hardy-Weinberg Equilibrium | A state in which allele and genotype frequencies remain constant from generation to generation when only Mendelian segregation and recombination are occurring. |
| p | Frequency of the dominant allele. |
| q | Frequency of the recessive allele. |
| p² | Frequency of homozygous dominant individuals. |
| 2pq | Frequency of heterozygous individuals. |
| q² | Frequency of homozygous recessive individuals. |
| p + q | 1. |
| p² + 2pq + q² | 1. |
| Five Hardy-Weinberg Conditions | No mutation, random mating, no natural selection, extremely large population size, and no gene flow. |
| Biological Species Concept | A species is a group of populations whose members can potentially interbreed in nature and produce viable, fertile offspring but cannot produce viable, fertile offspring with members of other groups. |
| Morphological Species Concept | Defines a species using measurable anatomical criteria. |
| Ecological Species Concept | Defines a species in terms of its ecological niche and how its members interact with living and nonliving parts of the environment. |
| Allopatric Speciation | Formation of new species in populations that are geographically isolated. |
| Sympatric Speciation | Formation of new species without geographic isolation. |
| Reproductive Isolation | Biological factors that prevent members of two species from producing viable, fertile offspring. |
| Prezygotic Barriers | Reproductive barriers that prevent mating or prevent fertilization if mating occurs. |
| Postzygotic Barriers | Reproductive barriers that prevent hybrid zygotes from developing into viable, fertile adults. |
| Hybrid | Offspring resulting from mating individuals from two different species or two true-breeding varieties of the same species. |
| Hybrid Zone | Geographic region where members of different species meet and mate, producing at least some offspring of mixed ancestry. |
| Speciation | Evolutionary process in which one species splits into two or more species. |
| Macroevolution | Evolutionary change above the species level. |
| Microevolution | Evolutionary change below the species level; change in allele frequencies in a population. |
| Punctuated Equilibria | Long periods of apparent stasis in the fossil record interrupted by relatively brief periods of sudden change. |
| Adaptive Radiation | A period of evolutionary change in which groups form many new species whose adaptations allow them to fill different ecological roles. |
| Mass Extinction | Elimination of a large number of species throughout Earth resulting from global environmental changes. |
| Pangaea | Supercontinent that formed near the end of the Paleozoic era when plate movements brought Earth's landmasses together. |
| Plate Tectonics | Theory that continents are part of large plates of Earth's crust that float on the hot underlying mantle; mantle movement causes continents to move over time. |
| Radiometric Dating | Technique used to determine the age of a fossil based on decay of radioactive isotopes. |
| Heterochrony | Evolutionary change in the timing or rate of an organism's development. |
| Paedomorphosis | Retention in an adult organism of juvenile features of its evolutionary ancestors. |
| Homeotic Genes | Master regulatory genes controlling the placement and spatial organization of body parts by controlling developmental fate of groups of cells. |
| Evolution Is Not Goal Oriented | Evolution does not work toward a predetermined goal. |
| Prokaryotes | Organisms with prokaryotic cells; an informal term for organisms in Bacteria or Archaea. |
| Protocells | Abiotic precursors of living cells with membrane-like structures that maintained internal chemistry different from their surroundings. |
| Pathogens | Organisms or viruses that cause disease. |
| Ribozymes | RNA molecules that function as enzymes. |
| Nucleoid | Non-membrane-enclosed region of a prokaryotic cell where its chromosome is located. |
| Plasmids | Bacterial DNA molecules that can carry genes such as antibiotic-resistance genes. |
| Transformation | Assimilation of external DNA by a cell; can result in horizontal gene transfer. |
| Transduction | Process in which phages carry bacterial DNA from one bacterial cell to another. |
| Conjugation | Direct transfer of DNA between two prokaryotic cells that are temporarily joined. |
| Four Steps for Origin of Simple Cells | Abiotic synthesis of small organic molecules → joining small molecules into macromolecules → packaging molecules into protocells → origin of self-replicating molecules. |
| Prokaryotic Genetic Recombination | Transformation, transduction, and conjugation. |
| Endosymbiont Theory | Theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by host cells; the engulfed cell and host evolved into one organism. |
| Endosymbiosis | A mutually beneficial relationship between two species in which one organism lives inside the cells of another organism. |
| Secondary Endosymbiosis | A process in which a heterotrophic eukaryotic cell engulfed a photosynthetic eukaryotic cell that survived symbiotically inside it. |
| Protists | An informal term for any eukaryote that is not a plant, animal, or fungus; most are unicellular, though some are colonial or multicellular. |
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808kadynt