Test Guide Unit 9 Ecology

Ecology ❖ Ecology - study of how organisms interact with each other/their environment ❖ Basic Vocab: ➢ Population - group of individuals (same species) that live in the same area; can breed + interact with one another ➢ Community - all organisms that live in same area ➢ Ecosystem - all organisms + nonliving (abiotic) factors that they interact with ➢ Abiotic factors - nonliving (ex. Soil, rocks, wind, water, temperature, sunlight) ➢ Biotic factors - all organisms that a certain organism can react with (ex. Birds, parasites, insects, prey, predators) ➢ Biosphere - ecosystem on a global scale ➢ Niche - what organism eats/needs for survival Population Properties ❖ Size - total # individuals in population (limited by # of births, # of deaths, immigration, emigration) ❖ Density - # of individuals per unit area/volume; sampling techniques (ex. Mark and recapture) are used to count them ❖ Dispersion - how individuals are spaced out in the area the population lives in, Three types are: ➢ Clumped - most common pattern (ex. Schools of fish) ➢ Uniform - evenly spaced out ➢ Random spacing - happens when nothing pressures individuals to live in groups/along (ex. Trees in forest) Population Growth ❖ Population grows exponentially until carrying capacity (max that environment is able to support) is reached ➢ Carrying capacity sometimes changes when the changes happen in the environment itself Strategies of Reproduction ❖ R-strategists: ➢ Lots of small young ➢ Little/no parenting ➢ Matures rapidly ➢ Reproduces only once ➢ Ex. insects ❖ K-strategists: ➢ Fewer but larger young ➢ More nurturing/involved parenting ➢ Matures slowly ➢ Reproduces multiple times ➢ Ex. mammals Community Structure & Interactions between Populations ❖ Communities are various populations and their interactions with each other/the environment ❖ 3 main categories of interactions: ➢ Competition - G. F. Gause made the competitive exclusion principle (states that 2 species cannot exist together in a community if they compete for the same resources) ■ Two possible outcomes for competition of same resources within community: ● Extinction/evolution by natural selection (resource partitioning) ● Divergence in evolution to avoid competition (character displacement) ➢ Predation ■ Is when animal eats animal or animal eats plant ■ Prey evolved defense mechanisms to protect themselves from predators ● Plants - spines, thorns, poisonous chemicals ● Animals - active defense (hiding, running) and passive defense (camouflage or mimicking poisonous animals) ➢ Feeding - relationships between organisms based on feeding ■ Mutualism - (+/+) relationship; beneficial to both organisms (ex. Gut bacteria and humans) ■ Commensalism - (+/o) relationship; beneficial to one organism, neutral to the other (ex. Whales and barnacles) ■ Parasitism - (+/-) relationship; beneficial to one organism, harmful to the other (ex. Tapeworms and humans) Food Chain ❖ Food chain - sequence of organisms where energy is transferred from trophic/feeding level → another level ❖ Energy moves through food chain from producers → herbivores → carnivores ➢ ~10% of energy in a trophic level changes to organic matter in trophic level that follows (shown in food pyramid) ➢ Producers ■ Convert light into chemical energy + have largest biomass ■ Ex. phytoplankton, photosynthetic algae, green plants ➢ Primary Consumers ■ Consume producers (are herbivores) ■ Ex. zooplankton, grasshoppers ➢ Secondary Consumers ■ Consume herbivores/primary consumers (are carnivores) ■ Ex. small fish, frogs ➢ Tertiary Consumers ■ Consume secondary consumers (are carnivores) ■ Have least biomass; unstable population size ■ Ex. hawk ❖ Productivity - how fast producers make organic matter ➢ Gross primary productivity: amt. of energy changed to chemical energy per unit time ➢ Net primary productivity: gross primary productivity − energy used (for respiration) ❖ Biological Magnification - more accumulated toxins in organisms at top of food chain than in lower organisms ❖ Decomposers - bacteria + fungi; break down organic material so nutrients can be recycled Ecological Succession - when disturbed ecosystem is rebuilt ❖ Primary ecological succession - no life or soil; pioneer organisms (lichens) arrive first to a disturbed ecosystem; soil building is also seen in this type of succession ➢ When ecosystem becomes stable again, is the climax community ❖ Secondary succession - disturbed ecosystem but still has soil Biomes - large areas that are classified by amt. of rainfall + temperature ❖ Marine ➢ Largest + most stable biome ➢ Responsible for majority of food/oxygen on Earth ➢ Further subdivided based on amt. of sunlight, depth, etc. ❖ Desert ➢ < 10 inches rainfall annually ➢ Very extreme temperature difference between day and night ➢ Many plants are drought resistant + often have shallow roots ■ Ex. cacti, mesquite, sagebrush ■ Some plants only grow after rain and die soon after ➢ Many animals move around during night, early morning, or late afternoon to avoid extreme heat ■ In the daytime, they stay underground/in shade ■ Ex. snakes, lizards, rodents, insects ❖ Tropical Rain Forest ➢ Near equator where there is lots of rain (humid) + have stable temperatures all year long ➢ 4% of land on Earth, but 20% of food production on Earth ➢ Extremely diverse; contain the most species of plants and animals ➢ Tall trees create canopy at the top ❖ Temperate Deciduous Forest ➢ Located in North America (northeast direction) ➢ More plant species diversity than taiga ➢ Trees here lose their leaves in winter ■ Decomposing fallen leaves create fertile soil ➢ Animal examples: squirrels, foxes, bears, deer ❖ Temperate Grasslands ➢ Large areas of land in tropical + temperate zones ➢ Low/unstable rainfall, so trees can’t survive ➢ Grazing mammals (bison) and burrowing mammals (prairie dogs) live here ❖ Conifer Forest (Taiga/Boreal Forest) ➢ Located in northern Canada + other northern regions ➢ Largest land biome ➢ Have some evergreen forests + lakes/ponds ➢ Lots of rainfall, extremely cold in winter (snows a lot) ➢ More animal species diversity than tundra ❖ Tundra ➢ Located even farther north in North America, Europe, Asia ➢ Very little rainfall; very cold (ground is frozen) ➢ No trees, many lakes/ponds ➢ Many insects, which attract birds in summer Chemical Cycles ❖ The Water Cycle ➢ Water evaporates from oceans, lakes, or plants through transpiration ➢ Water vapor forms clouds which causes water to rain down again ➢ Some water becomes groundwater, other water enters rivers/lakes/oceans ❖ The Carbon Cycle ➢ Cell respiration releases carbon dioxide and uses up oxygen ➢ Burning fossil fuels releases carbon dioxide ➢ Carbon dioxide is removed from atmosphere and oxygen is released by plants (photosynthesis) ❖ The Nitrogen Cycle ➢ Nitrogen-fixing bacteria live in roots (legumes) + convert free nitrogen to ammonium ions (NH4+) ➢ Nitrifying bacteria change ammonium ions into nitrites (NO2-) and finally into nitrates (NO3-) ■ Plants absorb nitrates and are eaten by animals ➢ Denitrifying bacteria change nitrates back into free nitrogen ➢ Decomposers break down organic matter into ammonia (NH4+) Impact of Humans on the Biosphere ❖ Humans disturbed/destroyed/changed countless ecosystems through ➢ Deforestation ➢ Depleting/contaminating groundwater ➢ Destroying habitats ➢ Minimizing biodiversity ➢ Destroying ozone layer ➢ Climate change ➢ Acid rain ➢ Invasive species/toxins