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Flashcards

Speciation Definitions

Indi Taberner Biology NCEA Level 3 English 54 cards

Cards in this deck (54)

  1. 1Biological EvolutionThe process through which the characteristics of organisms change over successive generations, by means of genetic variation and natural selection. It is most commonly defined as "changes in gene frequencies in populations."
  2. 2SpeciesA group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding.
  3. 3SpeciationThe formation of new and distinct species in the course of evolution.
  4. 4PopulationA particular section, group, or type of people or animals living in an area or country.
  5. 5Gene PoolThe stock of different genes in an interbreeding population.
  6. 6AllelesAlternate forms of a gene which codes for the same characteristic but with a slightly different order of bases.
  7. 7DemeSub population of species with little to no gene glow with other population
  8. 8ClineSeries of demes down a geographical gradient (down a country) limited gene flow between, further down the gradient there is no gene flow
  9. 9Ring SpeciesWhen the cline is in a ring, connecting all the way around a country or land
  10. 10Genetic VariationDifferences/Variation in genetics
  11. 11Gene FlowGene flow is any movement of genes from one population to another and is an important source of genetic variation.
  12. 12ImmigrationImmigration is migration seen as the settling in one region (permanently or temporarily) of individuals coming from another region.
  13. 13EmigrationEmigration is migration seen as an the exit of individuals from one region (to another where they will settle permanently or temporarily).
  14. 14Genetic DriftOpposite of natural selection, is random where lots of individuals from the population die/are eliminated from gene pool, natural disaster, (bottleneck/founder effect are types), doesn't matter in big populations but is serious in small populations
  15. 15Bottleneck EffectA sharp reduction in the size of a population due to environmental events (such as earthquakes, floods, fires, disease, or droughts) or human activities
  16. 16Founder EffectThe reduced genetic diversity that results when a population is descended from a small number of colonizing ancestors.
  17. 17InbreedingBreeding between closely related animals over a long time
  18. 18OutbreedingBreeding from parents not closely related
  19. 19Natural SelectionThe process in which inheritable traits that make an individual more likely to survive long enough in its environment to reproduce become more common in the population over successive generations.
  20. 20Selection PressureAn agent of differential mortality or fertility that tends to make a population change genetically.
  21. 21Adaptive AdvantageOrganizations with an adaptive advantage achieve superior outcomes in a turbulent environment
  22. 22Stablising SelectionExtreme phenotypes are selected against and average phenotypes are selected for
    (The most common mode)
  23. 23Disruptive SelectionIndividuals at both extremes of the distribution are selected for simultaneously. Average phenotypes are at a disadvantage and are selected against.
  24. 24Directional SelectionA single phenotype is selected for and the allele frequency continually shifts in one direction. (e.g. breeders often select for one characteristic in animals)
  25. 25Sexual SelectionMales or females compete for partners, with the heritable characteristics of the winners being passed on. Members mating, choose traits, choose partners
  26. 26Gene MutationA main source of genetical variation - variation in a gene pool, random changes within individual genes that may result in the production of new alleles. Result from errors in DNA replication, or from external factors
  27. 27Chromosomal MutationA type of mutation that involve the structure of chromosomes and thus affect whole genes
  28. 28MutagenAn external factor that causes mutation eg. high energy radiation, groups of chemicals, viruses
  29. 29HaploidA single set of unpaired chromosomes. The number of chromosomes in the gametes (abbreviated to n)
  30. 30DiploidContaining two complete sets of chromosomes, one from each parent.
    The number of chromosomes in the zygote (abbreviated to 2n)
  31. 31PloidyThe number of chromosomes in a cell.
  32. 32PolyploidyEvery chromosome is represented three or more times so that instead of being diploid (2n), the individual is triploid (3n) or tetraploid (4n), hexaploid (6n), etc.
  33. 33AutopolyploidyInvolves the multiplication of the entire genome within a single species. Results from the failure of chromosomes to separate during cell division because the spindle doesn't function properly (during meiosis - nondisjunction)
  34. 34AllopolyploidyResults from hybridisation between species. Comes from different species - hybrid infertile doubles chromosome
  35. 35Instantaneous SpeciationThe production of an individual(s) that is reproductively isolated from its parent and is capable itself of reproduction and establishing a new population.
  36. 36Sympatric SpeciationClosely related species that live in the same geographic location. One species gives rise to two or more species without prior geographic separation.
  37. 37Allopatric SpeciationSpeciation that occurs due to a species' being separated by a geographical barrior
  38. 38Niche differentiationRefers to the process by which competing species use the environment differently in a way that helps them to coexist.
  39. 39Reproductive Isolating MechanismsA collection of mechanisms, behaviors and physiological processes that prevent the members of two different species that cross or mate from producing offspring, or which ensure that any offspring that may be produced are sterile.
  40. 40Prezygotic Isolating MechanismsPrezygotic isolation prevents the fertilization of eggs. Includes geographical, structural, ecological, temporal, behavioural and gametic isolation
  41. 41Postzygotic Isolating MechanismsPostzygotic isolation prevents the formation of fertile offspring.
    Sperm may fertilise eggs of different species to form a hybrid. Hybrids are usually prevented from producing viable offspring by postzygotic isolating mechanisms - hybrid inviability, hybrid sterility and hybrid breakdown
  42. 42Fossil EvidenceThe fossil record provides ancient DNA which allows genetic analyses of extinct populations and species that give insight into genetic differentiation, among other processes. If there are no intermediates found - Punctuated, If there are intermediates - Gradualism
  43. 43BiogeographyThe study of the geographic distribution of species; evidence of evolution is provides by the natural geographic distribution of related species, both past and present. Evidence of biogeographical relatedness is supported by fossil evidence and modern molecular analysis.
  44. 44Molecular ClockThe average rate at which a species' genome accumulates mutations, used to measure their evolutionary divergence and in other calculations.
  45. 45Mitochondrial DNAMitochondria are not subject to meiosis and their DNA does not undergo any recombination - changes in mtDNA are the result of gene mutation only. As gene mutations in mtDNA occur at a much more rapid rate and is more steady, it is best used as a molecular clock. Is exclusively passed on down the female line - doesn't recombine in mitosis.
  46. 46Phylogenetic TreeA diagram that show the relationship of different groups and the likely time of their divergence from a common ancestor. Shows their phylogeny—based upon similarities and differences in their physical or genetic characteristics.
  47. 47GradualismA model of evolution which theorizes that most speciation is slow, uniform and gradual. When evolution occurs in this mode, it is usually by the steady transformation of a whole species into a new one
  48. 48Punctuated EquilibriumOften involves the formation of many different species that are no longer closely related. There are a few transitional fossils, because the rapid pace of the change.
  49. 49Divergent EvolutionDivergence occurs when two or more species result from a common ancestor - typically by allopatric speciation. Caused by geographical barriers, the species have different evolutionary processes (RIMs). All evolutionary pathways diverge at the genetic level.
  50. 50Adaptive RadiationInvolves the rapid evolution of a large number of species from an ancestral group to occupy a variety of different ecological niches that may have become suddenly available. (Divergence at a very large scale)
  51. 51Homologous StructuresHave a common ancestral origin, but are now very different in function and form. (The similarity in structure indicates common ancestry, while difference in function indicates adaptation to different selection pressures due to different environments)
  52. 52Convergent EvolutionOccurs when two or more unrelated species evolve to resemble each other as a result of being subject to similar selection pressures. Convergence is purely phenotypic.
  53. 53Analogous StructuresStructures with different evolutionary origins that appear very similar because they carry out the same or very similar function.
  54. 54Co-evolutionTwo species each exert a selection pressure on each other; a change in a feature of one species acts as a selection pressure for change in a feature of another species. eg. cheetah kills slow antelope - selects for faster antelope - selects for faster cheetah, and so on.

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NCEA Level 3 Biology (Speciation) Flashcards on Speciation Definitions, created by Indi Taberner on 04/11/2016.
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Indi Taberner
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