Biology Evolution

• Adaptation


  A process that helps an organism survive and produce in a particular environment
• Types of adaptation


  • Structural
  • Behavioral
  • Physiological
• Physiological adaptation


  Does it without thinking, can't stop it (e.g. hibernation)
• Structural adaptation


  Physical characteristics (e.g. long legs to swim better for aquatic organisms)
• Behavioral adaptation


  Does it deliberately (e.g. migration)
• Mimicry


  Structural adaptation where a harmless species resembles a harmful species
• Batesian mimicry


  Shares similar traits from the model but isn't actually harmful (e.g. colorful frog resembles poisonous frog)
• Mullerian mimicry


  Two or more species have similar characteristics and they are also actually harmful
• English peppered moth


  • Flecked moths could camouflage well amongst trees in clean air, but when air became polluted, black moths increased
• Variation


  Offspring have a combination of genetic material from both parents, causing variation in each offspring's genetic makeup
• Mutation


  Permanent variations that can happen continuously in the DNA of any living organism
• Mutagens


  Environmental agents that can cause mutations
• Characteristics of mutations


  • Cells would die, malfunction, or multiply more than they should
  • Some mutations can be beneficial
• Mutations in gamete cells

  If a mutation alters the gamete, the DNA may be passed onto the offspring
• Selective advantage


  Genetic advantage that improves an organism's chance of survival
• Rapid reproduction


  Ability to reproduce really fast, increasing the chance of a new allele forming from a random mutation
• Antibiotic resistant bacteria


  • When antibiotics destroy bacteria, some bacteria with random mutations survive and pass on the resistance
• Development of adaptations


  Adaptations are an accumulation of gradual changes that help an organism survive and reproduce, resulting from random heritable mutations in DNA
• Adaptations over multiple generations

  Adaptations are developed to increase an organism's biological fitness in a specific environment, allowing organisms with these adaptations to survive longer and reproduce, passing them on to the next generation
• Natural selection


  Characteristics of a population change over many generations, as adaptations are created in response to their environment, giving them increased biological fitness to pass on to offspring
• Selective pressure


  Biotic factors that influenced a species' adaptations to their environment, contributing to natural selection
• Natural selection is situational


  Natural selection doesn't have foresight, it is entirely a response to changing environments, not a plan for the future
• Biological fitness


  How well an organism can survive in their environment and if they can survive long enough to reproduce
• Artificial selection


  When humans choose which organisms to breed together to get the offspring with the most desirable traits
• Gene banks


  Contain the genetic information of early ancestors of a species, serving as a "backup" in the event of disasters that wipe out the majority of a gene pool
• Georges-Louis Leclerc was one of the first to publicly challenge the idea that life forms are unchanging (evolving)
• Similarities between apes and humans made Leclerc speculate they might have a common ancestor
• Paleontology


  Study of ancient life through fossil analysis
• Fossils


  Preserved remains of once living organisms, contributing to the study of evolution
• Georges Cuvier


  Credited with developing paleontology, discovered that each layer of rock (stratum) had a unique group of fossils, and that the deeper the stratum, the more contrast there was between the species and modern life
• Cuvier's idea


  Catastrophes like natural disasters periodically destroyed species living in a particular region, after which species from other regions would repopulate the area
• Charles Lyell


  Rejected Cuvier's idea of natural disasters, proposed that geological processes operate at the same rate as they do today (uniformitarianism), and suggested that slow subtle changes could happen over time and result in substantial differences
• Jean Baptiste Lamarck


  Observed a "line of progression" where a series of fossils from older to recent result in a modern version of the species, and believed that as species increased complexity, over time they would achieve a level of perfection
• Lamarck's theory


  Inheritance of acquired characteristics - characteristics/traits acquired during an organism's lifetime could be passed on to their offspring (false)
• Charles Darwin


  Developed comprehensive theory explaining population changes, proposed that all life descended from some unknown organism, and that descendants of this organism spread out over different regions and developed traits that helped them survive better in their respective environments
• Darwin's theory of natural selection

  • Organisms produce more offspring than the environment can support, individuals that have traits that make survival easier are more likely to pass these traits to offspring, competition for resources means only the "fittest" survive and pass on their traits
• Natural selection doesn't demonstrate progress and has no set direction, it results from species that are better adapted to their environment surviving longer and producing offspring with the same trait, eventually spreading to the entire species
• Descent with modification


  Changes are slow and gradual, natural selection doesn't plan ahead but is a response to changing environments
• Fossil record


  Sedimentary rocks provide a fossil record showing the history of life and the species that were alive in the past

  
• Key events in the fossil record

  • 3.8 billion years ago: Prokaryotic cells first appear
  • 3.5 billion years ago: Fossils of primitive cyanobacteria first appear
  • 2.5-2 billion years ago: Eukaryotic cells appear
  • 1.5 billion years ago: Multicellular eukaryotic organisms first appear