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General Biology: Evolution and Development Concepts

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  • What is the role of Bicoid in development?

    Bicoid is a morphogen gradient; its concentration determines cell fate during early development.

  • What do Hox genes control?

    Hox genes control the body plan and contain a conserved DNA-binding domain called the homeobox.

  • What are toolkit genes in evo-devo?

    Toolkit genes are the same genes with different regulation, leading to different body plans across species.

  • What was Lamarck's theory of evolution?

    Lamarck proposed that acquired traits are passed on to offspring, which is incorrect.

  • What is Darwin's key idea about evolution?

    Darwin emphasized heritable variation and differential survival and reproduction as drivers of evolution.

  • List the 4 postulates of natural selection.
    1. Variation exists in populations
    2. Variation is heritable
    3. More offspring produced than survive
    4. Survival/reproduction is non-random and tied to heritable traits
  • What conditions must be met for Hardy-Weinberg equilibrium?

    No mutation, no selection, random mating, no genetic drift, and no gene flow.

  • What does violation of Hardy-Weinberg conditions indicate?

    Violation of any of the 5 conditions means evolution is occurring in the population.

  • Name the 4 evolutionary processes.
    1. Natural selection
    2. Genetic drift
    3. Mutation
    4. Gene flow
  • Describe stabilizing selection.

    Stabilizing selection reduces variation and favors intermediate phenotypes.

  • Describe directional selection.

    Directional selection shifts the population mean toward one extreme phenotype.

  • Describe disruptive selection.

    Disruptive selection favors both extremes and can split a population into two groups.

  • What is balancing selection?

    Balancing selection maintains multiple alleles in a population, such as through heterozygote advantage.

  • What is a population bottleneck?

    A bottleneck is a population crash where survivors are random, reducing genetic diversity.

  • What is the founder effect?

    The founder effect occurs when a small group colonizes a new area, reducing genetic diversity and fixing alleles randomly.

  • Define homology and homoplasy.

    Homology is shared ancestry; homoplasy is similarity due to convergent or analogous traits.

  • What is a synapomorphy?

    A synapomorphy is a derived trait shared by a clade, indicating common ancestry.

  • What principle does parsimony in phylogenetics follow?

    Parsimony favors the evolutionary tree with the fewest changes.

  • Name the three species concepts.
    1. Biological: reproductive isolation
    2. Morphological: form differences
    3. Phylogenetic: shared derived traits
  • What is allopatric speciation?

    Allopatric speciation occurs when geographic barriers cause populations to diverge.

  • What is sympatric speciation and a key mechanism in plants?

    Sympatric speciation occurs without geographic barriers; polyploidy is a common mechanism in plants.

  • What is reinforcement in speciation?

    Reinforcement is selection that strengthens prezygotic isolation in hybrid zones.

  • What biases exist in the fossil record?

    Fossil record biases include preservation of hard parts and over-representation of certain environments.

  • What is the molecular clock?

    The molecular clock uses mutation rates to estimate divergence times between species.

  • Define adaptive radiation.

    Adaptive radiation is rapid diversification of a single lineage into many ecological niches.

  • What was the Cambrian explosion?

    The Cambrian explosion (~539 million years ago) was a rapid appearance of most animal body plans.

  • What is the Phanerozoic eon?

    The Phanerozoic is the last 539 million years of geologic time, divided into Paleozoic, Mesozoic, and Cenozoic eras.