Adapative and Non Adaptive Evolution

• What is non-adaptive evolution known to cause?

  Evolutionary change
• How does non-adaptive evolution affect allele frequencies?

  It changes allele frequencies
• What is the impact of non-adaptive evolution on population fitness?

  It does not increase population fitness
• What are the processes involved in non-adaptive evolution?

  Mutations, genetic drift, and gene flow
• What is the role of mutations in non-adaptive evolution?

  They create new gene versions and change existing genes
• How does genetic drift affect allele frequencies?

  It changes allele frequencies due to random chance

  
• What is the effect of genetic drift on genetic diversity?

  It decreases genetic diversity

  
• How does population size influence genetic drift?

  It is weak in large populations and strong in small populations
• What are the two main types of genetic drift effects?

  1. Founder effect: Small groups start new populations
  2. Bottleneck effect: High mortality leads to loss of genetic diversity

  
• What is an example of the founder effect in genetic drift?

  Native mice in New York separated by urban developments

  
• What is the bottleneck effect in genetic drift?

  It is a reduction in genetic diversity due to high mortality

  
• What happened to the greater prairie chicken population from the 1800s to 1993?

  It decreased from millions to less than 50

  
• How did the population of N. Elephant seals change from the 1700s to 1890?

  It decreased from millions to 30
• What is gene flow in the context of evolution?

  It is the movement of individuals between populations
• What can barriers to gene flow lead to?

  They can lead to inbreeding
• What is adaptive evolution and its main mechanism?

  • Natural selection is adaptive
  • Traits that improve survival and reproduction develop and spread
  • Species become better suited to their environment
• What are the three classic patterns of selection in adaptive evolution?

  Directional, diversifying, and stabilizing selection
• What is directional selection?

  It favors one extreme trait version, decreasing diversity
• What is diversifying selection?

  It favors both extreme trait versions, increasing diversity
• What is stabilizing selection?

  It favors the intermediate trait version, decreasing diversity
• What is heterozygote advantage?

  It allows heterozygotes to resist harmful effects of recessive alleles
• What are the negative health impacts of inbreeding observed in Florida panthers?

  Weakened immune systems, cardiac defects, and decreased fertility
• What was done to address inbreeding depression in Florida panthers?

  Eight females were introduced from Texas in 1995
• What are the effects of inbreeding depression in purebred cats and dogs?

  • Weakened immune systems
  • Breathing problems
  • Tremors
  • Cancers
• What limits the action of inbreeding on allele frequency?

  It does not change allele frequency or diversity
• What does inbreeding increase in a population?

  It increases homozygosity
• What can inbreeding show in terms of traits?

  It can show unusual traits