Biology Exam 4

• Biotic factors


  • competition
  • predation
  • disease
  • presence/absence of pollinators
• Abiotic factors


  • geographic barriers
  • temperature
  • water
  • sunlight
  • nutrients
  • salinity
  • pressure
  • wind
  • pH
  • soil
• Temperature and water


  • The most influential abiotic factors, changes in temperature can affect biological processes
• Low temperatures


  Frost is the most important factor limiting geographic distribution of tropical and subtropical plants and reptiles
• High temperatures


  Can lead to coral bleaching
• The higher the elevation and more north the latitude


  The less precipitation
• Water's impact on distribution

  • important driver of biological composition as different plants are adapted to different water sources, and animals are adapted to those plants. Changes in water levels can cause plants and other organisms can drown with excess water or desiccate with too little
• Sunlight's impact on distribution

  • plants need light to survive although some are adapted to grow under dark conditions. In aquatic environments, water absorbs light which prevents photosynthesis at depths greater than 100 m. Too much light can damage DNA and proteins
• Photic zone


  An aquatic zone where there is enough light for photosynthesis
• Salinity's impact on distributions

  • freshwater animals gain water and have to constantly eliminate it, marine animals lose water and must drink water to compensate. Most plants are tolerant to salt while some coastal plants are adapted to salt, a rise in sea level can kill plants near the shore
• pH's impact on distribution

  • Can have large impacts on plants
• Global warming impacts include...


  geographical shifts in species ranges, extinction, ecosystem level effects (coral bleaching), and shifts of timing of seasonal traits/phenology (spring blooms, mating season, and migration)
• Global warming


  Human activities that increase the greenhouse effect
• Greenhouse effect


  The concentrations of atmospheric gases known as water vapor, CO2, and methane trap solar radiation near earth
• Ecology


  The study of interactions among organisms and between organisms and their environment
• Climate


  Average weather conditions in an area over a long period of time. Climate determines the occurrence of different biomes
• Weather


  Short-term environmental patterns such as temperature, precipitation, wind, and light
• Biome


  A group of ecosystems that share similar climates and typical organisms
• Abiotic


  Non-living factors
• Biotic


  Living factors
• Ectotherm


  An animal whose body temperature varies with the temperature of its surroundings
• Endotherm


  An animal whose body controls and regulates its temperature by controlling internal heat it produces
• Species range


  The geographical area within which a species can be found
• Species distribution


  Areas of the world in which a species lives
• Calculating per-generation growth rate using net productive rate (Rº)

  Take the sum of all lx * mx, where lx is the survival rate and mx is the number born per individual
• Predicting population growth over time using per capita growth rate r


  r = [(number of births ÷ total number of that organisms) - (number of deaths ÷ total number of that organism) x total number of that organism]
• Factors regulating populations


  • Density-dependent factors
  • Density-independent factors
• Density-dependent factors


  Influence varies with the density of the population, e.g. parasitism, predation, and competition
• Density-independent factors


  Influence is not affected by changes in the population size or density, e.g. physical factors such as weather, drought, flood, and fire
• Populations cannot grow exponentially forever
• Logistic growth


  A pattern where growth slows down as it approaches carrying capacity, K
• Exponential growth


  A pattern where growth of a population in an ideal environment is represented by a J-shaped curve when population size is plotted over time, r determines the slope
• As populations grow, resources become limited and population growth slows
• 1. r-selected species

  Have a high rate per capita population growth, but poor competitive ability, e.g. weeds
• 1. k-selected species

  Are more or less stable populations that are adapted to exist at or near carrying capacity
• Age structure


  The relative number of individuals in a defined age group that helps to predict future population growth
• Total fertility rate


  The number of offspring per female, the average of 2.3 offers zero population growth
• Ecological footprint of a human population


  Influences the earth's carrying capacity for humans, without enough land for survival in a sustainable world, the carrying capacity decreases since resources are scarce
• Population


  A group of interbreeding individuals occupying the same habitat at the same time
• Carrying capacity


  The largest number of individuals of a population that an environment can support