Mechanism of Evolutionary Change - Lecture 3

Cards (28)

  • Biological Diversity refers to the number and kinds of organisms living on Earth at a particular time.
  • Evolution is defined as a change over time, showing how present-day organisms have descended from ancient ones.
  • Natural Selection is a key factor for an organism to thrive and reproduce depends on how well suited it is to the environment.
  • Types of Natural Selection:
    • Directional Selection: occurs when a change in the environment causes a change in observable phenotypes, favoring those well-suited to the environment
    • Stabilizing Selection: intermediate phenotypes are more likely to survive in the environment
    • Disruptive or Diversifying Selection: extreme phenotypes are more likely to adapt to the environment
  • Artificial Selection:
    • Variation among organisms provided by nature, allowing humans to select useful variations through selective breeding
    • Breeders can produce a wide range of plants and animals using artificial selection
  • Nonrandom Mating:
    • Described as the selected probability of mating with another individual in the population
    • Inbreeding: individuals more likely to mate with close relatives, leading to potential inheritance of harmful recessive genes
    • Outbreeding: individuals select distant relatives as partners, leading to mating of similar phenotypes
  • Genetic Drift:
    • Caused by unpredictable changes in allele frequencies due to small population sizes
    • Population Bottleneck: sharp decline in population leading to reduction in genetic diversity
    • Founder Effect: loss of genetic variation due to migration of a small subgroup in a population
  • Mutation:
    • Change in gene structure caused by alterations in DNA sequence
    • Types of mutations: substitution, insertion, deletion, frameshift
    • Mutation may be neutral or beneficial
  • Gene Flow:
    • Also known as migration, involves transfer of genes from one population to another
    • Two types of migration: emigration and immigration
  • Biological Diversity includes questions about how organisms arose and how they are all related.
  • Fitness is an ability of an individual to survive and reproduce in a specific environment.
  • The concept of fitness is the central process of evolution by natural selection.
  • Natural Selection is when an individuals with characteristics that are not suited to the environment either die or live with few offspring, whereas individuals with characteristics that are very much suited to the environment survive and reproduce successfully.
  • Raphus cucullatus or the dodo bird is found on the small island of Mauritius in the Indian Ocean, east of Madagascar.
  • Dodo bird were nonflying, overweight, pigeon like birds that were allegedly unfit to the environment because they could not fly. This made them easy prey.
  • Their obesity, slowness and lack of intelligence of dodo bird are the common reasons cited by scientists for their extinction.
  • Dodo bird was present since the 1590s and was declared extinct in 1861.
  • Biological Diversity:
    • Refers to the number and kinds of organisms living on Earth at a particular time
    • Includes questions about how organisms arose and how they are related
  • Evolution:
    • Defined as a change over time, showing how present-day organisms descended from ancient ones
  • Natural Selection:
    • Key factor for an organism to thrive and reproduce, depending on how well suited it is to the environment
    • Fitness is the ability of an individual to survive and reproduce in a specific environment
    • Individuals with characteristics suited to the environment survive and reproduce successfully
  • Raphus cucullatus (Dodo bird):
    • Found on the small island of Mauritius in the Indian Ocean
    • Nonflying, overweight, pigeon-like birds that were allegedly unfit to the environment
    • Extinct since 1861 due to obesity, slowness, and lack of intelligence
  • Types of Natural Selection:
    • Directional Selection: Occurs when a change in the environment causes a change in observable phenotypes
    • Stabilizing Selection: Intermediate phenotypes are more likely to survive
    • Disruptive or Diversifying Selection: Extreme phenotypes are more likely to adapt to the environment
  • Artificial Selection:
    • Nature provides variation among organisms for humans to select useful variations
    • Done through selective breeding by farmers and breeders to produce desirable traits in offspring
  • Nonrandom Mating:
    • Described as the selected probability of mating with another individual in the population
    • Inbreeding: Mating with close relatives, leading to a higher chance of inheriting harmful recessive genes
    • Outbreeding: Mating with distant relatives, individuals with similar phenotypes are more likely to mate
  • Genetic Drift:
    • Mechanism of population change due to unpredictable changes in allele frequencies in small populations
    • Population Bottleneck: Sharp decline in population leading to reduced genetic diversity
    • Founder Effect: Loss of genetic variation due to migration of a small subgroup in a population
  • Mutation:
    • Change in the structure of a gene caused by alterations in the DNA sequence
    • Types of mutations include substitution, insertion, deletion, and frameshift
    • Mutations may be neutral or beneficial, affecting survival and reproduction
  • Causes of Mutation:
    • Mistakes in replication of genetic materials
    • Result of exposure to radiation or chemicals in the environment
  • Gene Flow:
    • Also known as migration, transfer of genes from one population to another
    • Two types of migration: emigration (gene leaves a population) and immigration (gene enters another population)