Transcript CS-Bio
CHAPTER 46 Community Structure and Biodiversity: A Summary AP Biology Spring 2011 WHICH FACTORS SHAPE COMMUNITY STRUCTURE? Where a species resides is its habitat whereas a niche is its role in the community Factors influencing niche of plant: soil, light, water, etc. WHICH FACTORS SHAPE COMMUNITY STRUCTURE? Species relationships: Commensalism: one species in the relationship is benefited and the other is unaffected WHICH FACTORS SHAPE COMMUNITY STRUCTURE? Species relationships: Mutualism: both species in a relationship benefit WHICH FACTORS SHAPE COMMUNITY STRUCTURE? Species relationship: Predation and parasitism: one species benefits at the other species’ expense MUTUALISM Mutualistic relationships are common in the environment Insects serve as pollinators, while plants provide nectar for the insect Legumes change nitrogen into a usable form and plants provide nutrition In lichen, fungi serves to soak up water while plant again provides nutrition Anemone fish protects the anemone and the anemone provide defense for the fish in the form of nematocysts Perhaps mitochondria where bacteria that sought protection in cells while providing energy to the cell COMPETITION INTERACTIONS Competition between species may result in evolution by natural selection When two species of paramecium were in the same environment, one thrived and one died When two species of salamanders were together in the same area, both populations decreased due to competition COMPETITION INTERACTIONS Species may be able to survive together if they partition their resources In a study of finches in the Galapagos Islands, one species of finch developed a smaller beak so that they could utilize a different sized seed as a food source Minimize the competition PREDATOR-PREY INTERACTIONS The numbers of prey can influence the quantity and types of predators Type 1 response: fairly constant number of prey are killed Amount of prey killed depends on their density Ex. Spiders, filter feeders PREDATOR-PREY INTERACTIONS Type 2 response: number of prey killed depends on the skill level of the predator Initially, there are many more kills, but eventually it slows down since predators can only eat so much Ex. Large animals like tigers, wolves, etc. PREDATOR-PREY INTERACTIONS Type 3 response: number of prey killed increases at a slow rate, then quickly and finally levels off Could be due to predator switching to a different type of prey Predator could be learning more effective ways of hunting prey The rapid rise in kills could involve the prey running out of hiding places PREDATOR-PREY INTERACTIONS EVOLUTIONARY ARMS RACE Prey develop various defenses for survival Some have natural camouflage to hide from predators Some have warning colouration to alert predator to bad taste or possible stinging Ex. Bittern birds, caterpillars, lithops plants Ex. Yellow jacket Some illustrate mimicry where an organism appears like another organism that is dangerous or distasteful Ex. Viceroy butterfly mimicking monarch and other insects resembling yellow jackets EVOLUTIONARY ARMS RACE Predators develop various adaptations Some develop better hunting methods Ex. Swift cheetah Some utilize camouflage to ambush prey Ex. Undetectable scorpion fish and polar bear PARASITE-HOST INTERACTIONS A parasitic lifestyle benefits the parasite and usually harms the host Parasites may weaken the host or cause sterility A successful parasite should not destroy the host Often parasites utilize a vector to deliver the parasite to a suitable host organism Vectors include insects and other arthropods PARASITE-HOST INTERACTIONS A parasitoid is a parasite that lays eggs in an insect’s body and destroys it Parasites can be used as biological controls in an attempt to eliminate an undesirable organism STRANGERS IN THE NEST Social parasites are those that take advantage of another animal’s behavior Ex. Cowbird who lays its eggs in another bird’s nest so that the other bird serves as a foster parent ECOLOGICAL SUCCESSION Primary succession: when an area lacking soil is originally colonized Lichens and mosses settle first because they can inhabit an area with little or no soil Soil is developed from plant liter and other species settle ECOLOGICAL SUCCESSION Secondary succession: relates to an area’s recovery from a fire or natural disaster ECOLOGICAL SUCCESSION The factors that relate to the organisms that occur during succession are sometimes unpredictable Factors that determine the species population during succession are soil composition, climate and often chance events The intermediate disturbance hypothesis states that the number of species inhabiting an area is highest when the disturbances are less drastic ECOLOGICAL SUCCESSION SPECIES INTERACTIONS AND COMMUNITY INSTABILITY Keystone species: one that has an overwhelming effect on the environment Ex. Periwinkle snails, beavers, sea star SPECIES INTERACTIONS AND COMMUNITY INSTABILITY Geographic dispersal: when residents of established communities move out of their home range and successfully take up residence elsewhere Over a number of generations, population might expand its home range by slowly moving to outlaying regions Due to jump dispersal, organism may be moved far from its native habitat (rapidly transported across great distances) May be moved by continental drift, slow pace over long time period EXOTIC INVADERS Some exotic imported species may upset the natural balance in the new environment Common algae present in fish tanks can dominate natural waterways Kudzu plant from Japan is extremely is extremely fast growing and difficult to control in the US Australia attempts to control a rabbit infestation Hearty grey squirrels introduced to Europe out survive the native red squirrels BIOGEOGRAPHIC PATTERNS IN COMMUNITY STRUCTURE Biogeography: studies the natural location of species The greatest number of species settles close to the equator This is due to the amount of rainfall, temperature and the fact that tropical environments are well-established communities BIOGEOGRAPHIC PATTERNS IN COMMUNITY STRUCTURE Newly formed islands are an excellent habitat for studying speciation The equilibrium model of island biogeography attempts to predict the amount of speciation on an island The amount of speciation can be estimated by the land area of the island and its distance from the mainland