Chapter 22

• What is a Organism?

  Living being that is made up of different organs
• What is a Population?

  Group of organisms of the same species that interact with each other in the same environment
• What is a community?

  All organisms that interact with each other in a environment
• What is a ecosystem?

  A community of living organisms and their physical environment, interacting as a system.
• Biosphere


  World wide ecosystem
• What does a biosphere include?

  Air, water bodies, the land and soil
• What is evolution a result of?


  Heritable change in one or more characteristics of a population from one generation to the next
• What does evolution result in?

  Some organisms are more successful at survival and reproduction
• Can evolution lead to new species?

  Yes
• What can members of the same species have in common?

  Similar characteristics and can interbreed
• What is micro evolution?

  Small-scale changes in the genetic makeup of a population over time.
• What can micro evolutions lead to?


  New sub species
• what is macro evolution?


  Formation of new species or groups of related species over long periods of time on a large scale
• Who hypothseized existing species evolve from preexisting ones?

  Charles Darwin
• Who created the modern day understanding of evolution?

  Charles Darwin
• what was one of Darwin’s theories?

  evolution occurs From generation to generation because of interacting factors of genetic variation and natural selection
• Did Darwin know about the genetic basis of traits?

  No
• Natural Selection


  Changes Populations from Generation to Generation
• Natural Selection


  • Genetic variation in traits may occur among individuals of a given species
  • The heritable traits are then passed from parents to offspring
  • Genetic variation is the result of genetic mutations
• Natural Selection


  • Individuals with heritable traits that make them better suited to their native environment tend to flourish and reproduce
  • Individuals less likely to survive and reproduce
• As a result of natural selection

  Certain traits that favor reproductive success become more prevalent in a population over time
• Natural Selection


  Changes populations from generation to generation
• Natural Selection


  • Not all members of a population necessarily have an equal chance of surviving and reproducing
  • By virtue of small phenotypic variations, some individuals are better adapted to their environment than are others
  • The better adapted individuals are more "fit" and tend to survive and reproduce, passing on their adaptations to the next generation in greater frequency than those adaptations of the less members of the population
• Survival of the fittest


  Alternative phrase to natural selection
• Less adapted individuals


  • Decrease their ability to survive and pass the "negative" trait(s) to their offspring
• Biological evolution has left marks of evidence to compare "relatedness" between organisms that supports the theory of evolution
• Evidence of Evolutionary Change


  • Different organisms evolve from previous forms via descent, and that all organisms are connected by the passage of genes along the branches of the phylogenetic tree that links all of life
  • Includes studies of natural selection, selective breeding, biogeography, convergent evolution, the fossil record, and homologies
• Homologies


  Anatomical, developmental, and molecular similarities between organisms that occur due to descent from a common ancestor
• Selective Breeding


  • Breeding programs and procedures designed to modify traits in domesticated species
  • Breeders choose desirable traits to pass on to offspring
• Patterns of past evolution are often found in the natural geographic distribution of related species
• Convergent Evolution


  Two different species from different lineages show similar characteristics because they occupy similar environments
• Convergent Evolution


  • Ruby-throated hummingbird and hummingbird moth both beat their wings rapidly as they hover at flowers and obtain nectar with a long, thin beak
  • Aerial rootlets found in English ivy and wintercreeper
  • Antifreeze proteins found in different fish that live in very cold water environments
• Fossils


  Preserved remains of past life that provide evidence of evolutionary change
• Homology

  Similarity between organisms that occurs due to descent from a common ancestor
• Homology

  • Similarities in the bone structure of the forelimbs of humans, whales, and snakes
  • Developmental homologies like the one found in the gill slits of human embryos and the gill slits of fish
• Molecular Homologies

  Similarities in the DNA, RNA, and protein sequences of organisms that indicate evolutionary relatedness
• The physical characteristics (phenotypes) of every organism is mainly determined by the proteins they possess</b>
• Closely related organisms generally have a high degree of similarities in the sequences of their DNA, RNA, and proteins, while distantly related organisms show a pattern of dissimilarity
• Evolution at the molecular level also occurs as a result of changes in chromosome structure and number
• Chromosome changes

  • Comparisons between the three largest chromosomes in humans and primates (chimpanzee, gorilla, and orangutan)
  • Humans have one large chromosome 2 while primates have it divided into two separate chromosomes
  • Chromosome 3 is very similar, but orangutans have a large inversion