BSC2011 Unit 1 Vocab

  1. Natural Selection - survival/reproduction of the fittest



  1. Variation - any difference between organisms which has a genetic basis



  1. Adaptation - any heritable trait that helps an organism’s survival and reproduction in its PRESENT environment



  1. Convergent Evolution - similar phenotypes occur in distantly related lineages due to similar selective pressures



  1. Divergent Evolution - Lineages become increasingly different from each other as a result of different selective pressures



  1. Species - a group of organisms that are able to breed, and produce fertile, viable offspring



  1. Hybrids - the reproduction between organisms that would not normally breed with each other



  1. Reinforcement - hybrids are not good causing the parents to continue separately

  2. Fusion - hybrids are very good causing the parent species to eventually become one

  3. Stability - hybrids and parent species can both coexist and continue to be produced



  1. Gene Flow - the movement of alleles within and between populations



  1. Allopatric Speciation - physical separation of the two new populations from the parent population, then subsequent speciation



  1. Dispersal - when a few members of a population move to a new area

  2. Vicariance - when geographic barriers physically divide the population



  1. Adaptive Radiation - the relatively rapid evolution of many species from a single ancestor (drop fish into fishless river)



  1. Sympatric Speciation - occurs when both new populations inhibit the same geographical range as the parent species (can be caused by temporal/behavioral reproductive isolation)



  1. Gradual Speciation - species diverge gradually over time and changes occur in small intermediate steps



  1. Punctuated Equilibrium - new species diverge quickly from the parent species and then remain unchanged for long periods of time



  1. Gene - unit of dna, transmits genetic information, codes for a specific protein



  1. Phenotype - observable trait of an individual, determined by genotype



  1. Genotype - Specific alleles present in an individual



  1. Diploid - 2n, 2 copies of each chromosome, somatic (body) cells, mitosis produces two diploids from one diploid parent cell



  1. Haploid - n, 1 copy of each chromosome, gametes (egg & sperm), meiosis produces four haploid cells from one diploid parent cell



  1. Microevolution - small-scale changes in allele frequency of a population, changes within a gene pool,  from one generation to the next (dogs, wolves, foxes, etc!)



  1. Macroevolution - large-scale changes in allele frequency of a population, extends over a long period of time, gives rise to new species (fish thing to humans!)



  1. Allele Frequency - the rate at which a specific allele occurs in a population



  1. Genotype Frequency - the rate at which a specific genotype occurs in a population



  1. Population Genetics - measures the effect of natural selection on allele and genotype frequencies in a population



  1. Gene Pool - the sum of all alleles present within a population



  1. Hardy-Weinberg Equilibrium - no gene flow, natural selection mutation, or genetic drift, with random mating



  1. Genetic Drift - when allele frequencies change rapidly with no apparent advantage



  1. Founder Effect - individuals leave their parent population to inhabit new areas (lost!)



  1. Bottleneck Effect - an event that drastically reduces population size and only certain individuals survive



  1. Gene Flow - the flow of alleles in and out of a population due to migration



  1. Adaptive Evolution - when natural selection selects for beneficial traits/phenotypes, and against deleterious traits/phenotypes



  1. Stabilizing Selection - selective pressure for the average phenotype



  1. Directional Selection - selective pressure for one extreme phenotype



  1. Disruptive/Diversifying Selection - selective pressure for both extreme phenotypes



  1. Frequency Dependant Selection - see below



  1. Positive - selection for common phenotypes

  2. Negative - selection for rare phenotypes



  1. Sexual Selection - occurs when males’ ability to mate is more variable than females (ex. Bigger or prettier males have a better chance)



  1. Sexual Dimorphism - when males and females of a species exhibit phenotype differences beyond reproductive organs (ex. color)

  2. Handicap Principle/Good Genes Hypothesis - phenotype is such a disadvantage that only the fittest males can survive without it, honestly signalling to females of the male’s superior genetic quality



  1. Taxonomy - the international classification system used to name organisms in a hierarchical manner (order from most to least inclusive: Domain, Kingdome, Phylum, Class, Order, Family, Genus, Species) (Dear King Philip Came Over For Good Soup)



  1. Phylogeny - evolutionary history of organisms and their relationships to other organisms



  1. Rooted - single common ancestor, “root” of phylogenetic tree



  1. Branch Point - indicates a single lineage that evolved from the common ancestor



  1. Basal Taxon - an unbranched lineage that evolved from the common ancestor



  1. Sister Taxa - two lineages stemming from same branch point (node)



  1. Polytomy - a branch with three or more lineages



  1. Homologous Structures - physical or genetic traits that are similar due to common ancestry



  1. Analogous Structures - similar physical or genetic traits that evolved separately in two (or more) organisms that do not share a common ancestor



  1. Shared Derived Characters - a novel evolutionary character not present in an ancestor, only descendants



  1. Shared Ancestral Characters - a character that originated in an ancestor of the taxon



  1. Apomorphy - a novel derived character



  1. Synapomorphy - character shared by the last common ancestor 

  2. Autapomorphy -  novel character present in only one group, not present in most recent common ancestor



  1. Plesiomorphy - shared ancestral character, present in ancestor and descendants



  1. Monophyletic - consists of a common ancestor and all descendants



  1. Paraphyletic - consists of an ancestral species and some, but not all, descendants



  1. Polyphyletic - includes distantly related species but does not include their most recent common ancestor