En Sci MT

• Evolution


  • All species descended from earlier ancestral species
  • Changing genetic make-up in a population over time
  • Accepted scientific explanation of how animals adapt and survive
• Big bang - Earth: hot and disorganized
• Macroevolution


  • Long term, large scale changes in the population
• Microevolution


  • Small genetic changes in the population
• Gene pool


  All genes in a population
• Mutation


  • Random change in structure of DNA
  • Generally, a mutation is beneficial for survival (i.e. adaptation)
• Natural selection


  Individuals that have traits that benefit survival
• Microevolution


  Changes in the gene pool of a population over time that result in changes to the varieties of individuals in a population such as a change in a species' coloring or size
• Macroevolution


  If the changes are over a very long time and are large enough that the population is no longer able to breed with other populations of the original species, it is considered a different species
• Natural selection


  • Genetic variability in a trait within population
  • Trait is heritable
  • Differential reproduction - some individuals leave more offspring than do others due to traits that favor survival
• Adaptive (heritable) trait


  Helps survival and reproduction under current environmental conditions
• Ecological niche


  • Role of organism in the ecosystem
  • Includes interaction with biotic and abiotic factors
• Habitat


  Physical location
• Stratification of niches, habitats allows many different species to coexist. This is biodiversity.
• Generalist species


  • Broad niche
• Specialist species


  • Narrow niche
• Environmental conditions consistent - favors specialists. Fewer competitors, food plentiful
• Rapidly changing environmental conditions - favors generalists. More adaptable
• Speciation


  Different environmental conditions lead to evolution into 2 different species
• Reproductive isolation leads to speciation
• Arctic fox and gray fox are different species due to geographic isolation
• Extinction


  When environmental changes occur, species must evolve to adapt. Otherwise...
• Types of extinction


  • Background extinction: normal and slow rates
  • Mass extinction: quick, involving many species at once
  • Mass depletion: higher than mass extinction
• 99% of species that have existed on earth are now extinct
• Changes in biodiversity has leveled off during the last 1.8 million years
• Adaptive radiation - after mass extinctions, numerous new species evolve to fill vacated niches
• It takes 1-10 million years for adaptive radiation to rebuild biodiversity
• Human impacts have accelerated extinction
• Artificial selection


  • Artificially selecting superior genetic traits
• Artificial selection


  • Agriculture
  • Hatcheries
  • Pets
• Genetic engineering


  • Gene splicing
  • Species creation in laboratories
  • Takes less time than artificial selection
• Genetic engineering has a 1% success rate and concerns about leading to more abortions and only being available to the wealthy
• Biomes


  Major vegetation types on land based on different climates and atmospheric conditions
• Biomes


  • Forests
  • Grasslands
  • Deserts
• Aquatic life zones


  • Saltwater (coastal zone, open ocean, estuary, coral reefs and mangrove forests)
  • Freshwater (standing water, flowing water)
• 71% of the Earth is covered by saltwater
• Coastal zone has the majority of marine species (90%) and most commercial fisheries and interaction with land and humans
• Open ocean covers 90% of the ocean area
• Estuaries are where rivers meet the ocean
• Precipitation and temperature are the two most important factors influencing vegetation in the formation of biomes