Ecology

• Abiotic factors are nonbiological components of an environment, such as temperature, moisture, soil chemistry, and other physical factors
• Biotic factors are the biological components of an environment, or all the organisms in an ecosystem
• Macroclimate is the climate that includes all the abiotic factors and may not effect organisms directly always
• Microclimate is the climate that immediately surrounds organisms that has the greatest effect on them
• How does latitude affect sunlight intensity?

  Earth's spherical shape causes the intensity of incoming solar radiation to vary from the equator to the poles
• What causes the seasons?

  Earth is tilted on its axis at a fixed position of 23.5 degrees perpendicular to the plane on which it orbits the sun (changes illumination and thus seasons based on hemisphere)
• Adiabatic cooling is when warm air holds more water vapor than solid air which causes rising air near the equator to carry moisture upward, and then release it as rain once the air expands and cools
• Explain how mountains affect rainfall

  When warm, moist air moves inland and is blocked by a mountain range, the air rises to cross the mountains, which then cools and releases heavy rainfall on the windward side, but forms a rain shadow on the leeward side
• Lake Zonation

  A) littoral zone

  B) limnetic zone

  C) aphotic zone

  D) photic zone

  E) benthic zone

  
• Marine Zonation

  A) intertidal zone

  B) continental shelf

  C) neritic zone

  D) oceanic zone

  E) benthic zone

  F) photic zone

  G) pelagic zone

  H) aphotic zone

  I) abyssal zone

  
• Lakes undergo a seasonal turnover, which exchanges oxygen-rich, nutrient-poor surface waters with oxygen-poor, nutrient-rich deep water
• Wetlands occur at the borders of freshwater environments, such as marshes and swamps, which hold a diverse array of microorganisms, algae, plants, invertebrates, and vertebrates
• Streams and rivers start as seeps that flow downhill and collect into streams, which then merge into rivers. They contain 3 habitats: riffles, pools, and runs.
• Estuaries are coastal bodies of water with access to both the ocean and fresh water from rivers, often contain low salinity on river enters, and high salinity where the ocean enters
• Intertidal zones are the regions of shoreline between low and high tides, and are often alternately submerged and exposed by tides
• Ocean pelagic biomes are the water-filled regions, made up of the neritic zone that is the shallow water above continental shelves, and the oceanic zone that is the deep water beyond them
• Coral reefs exist primarily in the tropics, and are some of the most productive ecosystems, and are typically found in the neritic zone
• The marine benthic zone is the ocean floor and bottom sediments
• Tropical forests:

  • Tropical rain forests
  • annual rainfall exceeds 250 cm
  • mean temp is at least 25°C
  • humidity is above 80%
  • the most diverse terrestrial habitats in the world
  • Tropical deciduous forests
  • winter drought reduces photosynthesis
  • most trees drop their leaves
  • Tropical montane forests
  • productivity is limited by low temps, high humidity, and sunlight-blocking clouds
• Deserts form where rainfall averages less than 25 cm per year, and contain sparse vegetation but abundant small animals
• Savannas are grasslands with few trees, typically adjacent to tropical deciduous forests
• Chaparrals are a scrubby mix of short trees and low shrubs, and most plants are dormant during hot, dry summers, causing lightning to spark frequent fires
• Temperate grasslands include prairies, steppes, pampas, and veldt that often have drought-tolerant perennials, and large grazing mammals, burrowing mammals, and predators
• Coniferous forests often expanse circumporally into taigas (boreal forests), that have large herbivorous and carnivorous, small mammals, and flying insects
• Temperate broadleaf forests grow at low to mid-altitudes with warm summers and cold winters, and have plants that shed leaves in winter, with predominantly small mammals
• Tundra:

  • arctic tundra
  • stretches from the boreal forests to the polar ice cap in Europe, Asia, and North America
  • anaerobic conditions and low temperatures retard decomposition, causing wet detritus to accumulate
  • alpine tundra
  • occurs on high mountaintops throughout the world
  • photosynthetic activity is low
• Populations are groups of individuals of the same species that live together
• Population density is the number of individuals per unit or per unit volume of habitat
• Population dispersion is the spatial distribution of individuals within the geographical range
• Immigration is movement into a population
• Emigration is movement out of a population
• 3 patterns of dispersion:

  • random dispersion
  • individuals are distributed unpredictability within a uniform habitat
  • clumped dispersion
  • individuals group together due to patchy areas, social groups, or reproductive patterns
  • uniform dispersion
  • individuals repel each other and tend to be evenly spaced because resources are scarce
• Demography is the statistical study of the processes that change a population's size and density through time
• Life tables summarize the demographic characteristics of a population
• Survivorships curves show the rate of survival for individuals over the species' average life span
• Life history describe the lifetime patterns of growth, maturation, and reproduction of an organism
• Type I survivorship curves reflect high survivorship until late in life, typical of large animals that produce few young
• Type II survivorship curves show a constant rate of mortality in all age classes, seen in small animals subject to predation
• Type III survivorship curves reflect high juvenile mortality, followed by a period of low mortality once offspring reach a critical size
• The logistic model of population growth assumes that a population per capital growth rate, r, decreases as the population gets larger (approaches carrying capacity), assuming the population grows most when N = K/2, when N is population size and K is carrying capacity