Skip to main content
Indietro

General Biology: Natural Selection and Evidence for Evolution

I pulsanti di controllo sono stati cambiati in modalità "navigazione".
1/20

Termini in questo insieme (20)

  • Typological thinking

    Typological thinking views each species as an unchanging, perfect type; individual differences are unimportant.

  • Darwinian evolution

    Darwinian evolution explains species change through time by natural selection acting on heritable variation within populations.

  • Evidence for evolution: Fossil record

    The fossil record shows a change in life over time, including extinct species and transitional features linking ancestors to descendants.

  • Vestigial traits

    Vestigial traits are structures with no apparent modern function, like the human tailbone, indicating evolutionary history.

  • Homology

    Homology refers to shared ancestral traits among species, supporting common ancestry.

  • Darwin's four postulates of natural selection

    1) Variation exists in a population. 2) Some variation is heritable. 3) More offspring are produced than survive. 4) Survival and reproduction are nonrandom.

  • Fitness

    Fitness is an individual's ability to survive and reproduce relative to others in the population.

  • Adaptation

    An adaptation is a heritable trait that increases fitness in a specific environment compared to individuals without it.

  • Natural selection acts on individuals but evolution occurs in populations

    Selection determines which individuals survive and reproduce, but evolutionary change is seen as changes in trait frequencies in populations over generations.

  • Physiological change vs evolutionary change

    Physiological changes occur within an individual's lifetime and are not inherited; evolutionary changes occur across generations and involve changes in allele frequencies.

  • Example of physiological change: altitude acclimatization

    Increased red blood cell production at high altitude is a physiological change in an individual, not evolution.

  • Example of evolutionary change: Tibetan highlanders

    Tibetan populations have a high frequency of an EPAS1 allele that helps cope with low oxygen, an evolutionary adaptation.

  • Natural selection is not goal-directed

    Mutations occur randomly; natural selection sorts existing variation without foresight or planning.

  • Replica plating experiment

    Showed antibiotic resistance mutations exist before exposure, disproving the idea that bacteria mutate 'in order to' resist antibiotics.

  • Constraints on natural selection producing perfect organisms

    Constraints include history, trade-offs, limited variation, and changing environments.

  • Historical constraint example

    Human airway and food pipe cross in the throat, inherited from fish-like ancestors, causing choking risk.

  • Trade-off example: finch beak size

    Beak size favored in drought years differs from wet years, showing adaptation trade-offs depending on environment.

  • Variation constraint

    Natural selection can only act on existing heritable variation; no variation means no evolutionary response.

  • Changing environments constraint

    Organisms are adapted to past conditions; rapid environmental changes can outpace natural selection.

  • Summary of natural selection

    Natural selection increases frequency of heritable traits that improve fitness in the current environment but does not produce perfect organisms or work with foresight.