Ecosystems Section 4.2/pg.62 Biology 309 Chapter 4 What determines where an organism can live? Every species has its own range of tolerance ability to survive and reproduce under a range of environmental factors A habitat is the general place where an organism lives (including biotic and abiotic factors that affect it). A niche is the physical and biological conditions in which an organism lives AND the way in which it uses them. Life Beneath a Log Centipede: eats beetles. Worm: eats organic material from the soil. Millipede: eats decaying leaves. These organisms share the same habitat but each have a different niche. What kind of interactions occur within a habitat? 1. Predation: when one animal (the predator) captures and feeds on another animal (the prey). 2. Herbivory: when one animal (the herbivore) feeds on producers (such as plants). Predators can affect where prey populations can survive. Herbivores can help determine where certain populations of plants can survive. 3. Keystone species: when changes in a single species cause dramatic changes in the structure of a community Sea otters eat sea urchins which eat kelp. What do you think happened? Populations of Sea urchins increased, kelp population decreased and nearly vanished. This affected many other species as well. Without kelp to provide habitat, many other animals, including sea birds disappeared. Sea otters were a keystone species. 1
Any relationship in which two species live closely together is called symbiosis. Mutualism is a type of symbiotic relationship where both species benefit. Parasitism is a type of symbiotic relationship where one organisms lives in/on another organism and harms it. Commensalism is a type of symbiotic relationship where one organism benefits and the other is neither helped not harmed. Biomes Chapter 4.4 Chapter 4.4 2
What is a biome? Biomes are described in terms of abiotic factors and biotic factors. Each biome is associated with seasonal patterns of temperature and precipitation. Major Biomes: Tropical Rain Forest Average Temperature: 20 C - 34 C. Almost 2 meters of rain falls a year! Due to quick turnover of organic matter nutrients are not readably available in the soil. Tropical Rain Forest High level of competition for sunlight and nutrients. Canopy vs understory High turnover of organic matter. Vines Epiphytic plants Orchids, bromeliads, tropical ferns Tropical Rain Forest Active year round Adaptations for climbing, jumping, and/or flight. Many species have some sort of camouflage to hide from predators Parrots, monkeys, chimpanzees, gorillas, large insects, spiders, anaconda, emerald tree boa, jaguars, giant anteaters. Tropical Savanna Average Temperature: 16 C - 34 C. Also called tropical grassland, shrubland, or savanna Seasonal rain fall (monsoon season = 6 months). Soil is compact, dry, porous, and low in nutrients. 3
Tropical Savanna Adaptations: waxy leaf coverings, seasonal leaf loss, high silica content. Grasses grow from the bottom (not their tips) Tall grasses Acacia Trees Tropical Savanna Migratory animals Smaller animals burrow during dry season. Giraffe, elephant, zebra, wildebeest, lions, hyenas, vultures, meerkats. Temperate Forest Average Temperature: 6C - 28 C. Fertile soil, rich in humus (material formed from decaying leaves and organic matter). Four seasons Adequate rainfall to support tree growth (75-125 cm a year) Temperate Forest Mostly made up of deciduous and evergreen coniferous trees. Deciduous = falling off at maturity coniferous = seed bearing cones Oaks, pecan, maples, hickories, willows. Temperate Forest Animals must cope with changing weather. Hibernation Migrate Camouflaged from the winter Squirrels, rabbits, white-tailed deer, songbirds, wild hogs, fox raccoon, coyotes, bears. Taiga (Boreal Forest) Average Temperature: -10 C - 14 C. Boreal = north Soil is low in nutrient and acidic Winters are bitterly cold, summers are mild. Moderate precipitation (35cm-75cm) 4
Tagia (Boreal Forest) Conifers are well suited for this environment. Conical shape sheds snow, wax-covered needles, dark green color absorbs heat energy. Pines, cedars, spruce, fir tree Tagia (Boreal Forest) Staying warm is a major challenge Small extremities, fat layers, downy feathers, migration. Moose, hares, geese, migratory waterfowl, bears, wolves, lynx Temperate Grassland Average Temperature: 0 C - 25 C. Nutrient rich top soil (good for farming) Warm to hot summers and cool to cold winters Wet and dry seasons (25cm-75cm precipitation) Temperate Grassland Grassland plants (grow from the bottom) are resistant to grazing and fire. Wind dispersal of seeds. Lush perennial grasses, few scattered trees. Temperate Grassland Predation is a constant threat Deer, prairie dogs, buffalo, wolves, coyotes, badgers, grizzly bears, armadillo. Desert Average Temperature: 7 C 38 C. Very dry all year long (less than 25 cm precipitation) Hot during the day, cold at night. Dry, sandy soil, low in nutrients 5
Desert Many plants store water in their tissues Small leaf surface area Special form of photosynthesis that enables them to open their leaf pores only at night. Cacti, succulents, creosote bushes Desert Many get the water they need from their food. Many are nocturnal Large elongated ears and extremities help to regulate body temperature. Lizards, tortoises, mule, deer, camels, roadrunners, peccary, rattlesnakes, kit fox. Tundra Average Temperature: -26 C 12 C. Dry all year (less than 25cm precipitation) Strong, cold winds, short soggy summers Permafrost Nutrient poor soil Tundra By hugging the ground plants can avoid strong winds. Plants are adapted for poor soil Nitrogen-fixing bacteria attached to roots Grasses, sedges, moss, lichens Tundra Migration Adaptations for year round animals Natural antifreeze, small extremities, varied diet Lemmings, caribou, musk oxen, snowy owls, artic foxes, migratory birds. 6
Populations Section 5.1 Biology 309 Chapter 5 What is a population? A population is a group of organisms that are the same species and live in the same area. Healthy populations should grow and die at a relatively steady rate. Unless the population runs out of water, food, space, or is attacked by disease or a predator, it will continue to grow. What makes populations change? Births organisms being born Deaths organisms dying Immigration when individuals move into a population Emigration when individuals move out of the range 7
# organisms Population Size 9/22/2014 How do populations grow? Populations of organisms do not experience linear growth. What is exponential growth? Exponential growth is when the individuals in a population reproduce at a constant rate. Occurs when a population of organisms has all the food and space it needs, protection from predators and disease, and all waste products removed. Time The larger the population gets the more quickly it grows. Time Exponential Growth What is logistic growth? Logistic growth is when a populations growth rate slows or stops following a period of exponential growth. Shaped like an S-curve Carrying Capacity Logistic Growth with Carrying Capacity The largest number of individuals of a population that could be supported by a given environment. 8
Can a population grow forever? Section 5.2 Populations have the capacity to grow exponentially, but they are eventually limited by resources. A limiting factor is something that causes the growth of a population to decrease. Limiting factors determine the carrying capacity of a population. Density-Dependent Factors Limiting factor that depends on population size. Competition (Ex: availability of food) Disease can spread at exponential rates Predator/prey relationships Overcrowding Density-Independent Factors Limiting factor that affects all populations in similar ways, regardless of population size. Hurricanes, blizzards, fires, droughts, etc. 9