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Fighting/ competition Breeding Predator/ Symbiosis prey Different species compete for space or resources Causes animals to shift niches, adapt, evolve, migrate, or go extinct Animals become more specialized in what they eat/ where they live, when they are active Resource partitioning Character displacement Resource partitioning: Species evolve ways to share limited resources Different times of day/ year Different uses Different places Resource Partitioning in 5 species of Warbler 9-5 Resource partitioning via specialized feeding niches: Black skimmer seizes small fish at water surface Flamingo feeds on minute organisms in mud Brown pelican dives for fish, which it locates from the air Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Louisiana heron wades into water to seize small fish Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Herring gull is a tireless scarialavenger Ruddy turnstone searches under shells and pebbles for small invertebrates Knot (a sandpiper) picks up worms and small crustaceans left by receding tide Reduces competition and allows sharing of limited resources Piping plover feeds on insects and tiny crustaceans on sandy beaches Character displacement: Organisms change physical characteristics to become specialized Finches develop different size and shape beaks to reduce competition Predator eats prey species Predators often feed on the old/ sickly/ weak/ least fit This reduces competition among prey Predators control prey populations Problem: both hypotheses assume too much. Top-down- that lynx only eat rabbits and rabbits are only eaten by lynx Bottom-up- that only rabbits eat veggies Says that predators control prey pops Ex: Lynx eat rabbits so rabbits decrease. Rabbits decrease so there is less food for the lynx so the lynx crash. Less lynx means less predators so rabbits increase which allows the lynx to increase. Food sources influence population Ex: Rabbits eat too much vegetation so there isn’t enough food. Rabbits crash. Veggies grow back and then rabbits increase. Pursuit: Fast runners, ability to see from above, hunt cooperatively in packs Ambush: use camouflage to hide in plain sight and surprise their prey Chemical into prey warfare: bite and inject venom Run, swim, fly fast Highly developed sight/ smell/ hearing Protective shells/ bark/ spines Change colors Mimicry Camouflage Chemical warfare Mimicry Behaviors Plants develop many defense chemicals Pepper, caffeine, cyanide, cocaine, opium, strychnine, peyote, nicotine, rotenone, mustard, nutmeg, oregano, cinnamon, mint One organism lives on or in another organism and lives off of it Some parasites have a different host for each life stage Two species acting together so both benefit Pollination: bees and flowers Nutritional: coral and zooxanthellae Food + protection: ox pecker birds and rhinos Gut inhabitation: bacteria in termites/ humans to aid in digestion Two species interact and one benefits while the other is basically unaffected Species that are normally found in a particular area and they thrive in that environment A species that is not originally found in that location Some are harmful, others are benign, others are helpful A non-native species that DOES NOT harm it’s new environment Usually plants Ex: Goldfish Any non-native specie of plants, animals, etc that: Is harmful to native critters Negatively affects it’s new environment Can hurt new environment economically Examples: zebra mussels, brown anoles, African bees, Kudzu Zebra mussels (Great Lakes): Released via ship ballasts (1988) Filter out nearly all the phytoplankton (and small zooplankton) Bad and good 2004! Asian green mussels in Tampa Bay African bees: Introduced into the wild in South America (1956). The Africanized bee escaped and began to dominate honey bee. Kudzu (from Japan) Can be on purpose or on accident Monitor lizards and Burmese Pythons in South Florida/ Everglades Pets that are released when they get too big to handle safely Lionfish in the FL Keys Accidentally introduced during Hurricane Andrew Massive efforts are underway to curb the population Fishing, “delicacy” at restaurants, cookbooks Species that serve as an early warning system for damage/ danger/ pollution for a community Birds and butterflies Sensitive to environmental changes Both bird and butterfly populations are declining worldwide… Great indicator species Super vulnerable to environmental disruption at different points in their life cycles Eat bugs (pesticides), no shell on eggs (UV radiation), thin permeable skin that easily absorbs pollutants from the water and air Not just one thing Declining in every region of the world Habitat loss, prolonged drought, pollution, increase in UV radiation, increased parasitism, & overhunting 1. 2. 3. Tells us environmental conditions are degrading Amphibians are important parts of ecosystems They might have genetic secrets humans want for Rx Have great effect on ecosystems Loss can lead to population crashes or even extinction of other species Pollinators- bees, hummingbirds, butterflies, bats Top predators- wolves, sharks, bears, alligators Waste management- dung beetles Play a major role in shaping the community or habitat Benefits other species Ex: elephants knock down trees which allow grasses to grow. Antelopes eat the grass… Physical appearance/ distribution of species Species diversity (Species richness and evenness) Niche structure (how many and similarity) What does it mean if you say there is high species richness but low species evenness? Latitude Highest near equator Pollution Net (aquatic systems) primary productivity Habitat disturbance Time Species Equilibrium Model Rate at which new species immigrate and established species go extinct affects the number of different species found on an island Two factors influence the extinction and immigration rates: Size of the island- smaller island = fewer species therefore it has low immigration and high extinction rates Distance from nearest mainlandAssuming equal rate of extinction on two islands, one closer to mainland will have higher immigration rates Rate of immigration or extinction High Low Equilibrium number Number of species on island (a) Immigration and extinction rates Rate of immigration or extinction High Low Small island Large island Number of species on island (b) Effect of island size Immigration (near island) Rate of immigration or extinction Extinction Immigration (far island) Low Far island Near island Number of species on island (c) Effect of distance from mainland What is a niche? What is a fundamental niche? What is a realized niche? What is a generalist species? What is a specialist species? Communities change over time due to disturbances and changing ecological conditions This gradual change is known as ECOLOGICAL SUCCESSION Two types: primary and secondary Gradual establishment of biotic communities on nearly lifeless ground Takes a very long time Needs soil! Pioneer species- first species attach to bare rock, soil begins to gather Lichens, mosses Decompose and breakdown rock Patches of soil build up Early successional plant species: Small annuals (live only for 1 year) Small perennial grasses (live for at least 2 years) Thrive in harsh conditions, grow quickly Lichens and mosses are eliminated Hundreds to thousands of years later… Soil becomes deeper an contains more nutrients Midsuccessional plant species Herbs, Trees grasses, low shrubs Trees grow up and make lots of shade Late successional plant species Mostly trees Must be able to tolerate shade Can occur in small ponds Influx of sediments can allow plants to invade Turns into a marsh and then dry land Natural community has been disturbed somehow Soil still remains Much faster than primary succession Abandoned farmlands, cut/ burned forests, polluted streams, land that was dammed or flooded Any change in environmental conditions that disrupts a community Fire, drought, flooding, mining, clear-cutting, pesticides, invasion, etc… Not always bad Plants begin to grow back quicker because of the soil already present 3 factors that affect the rate of succession Facilitation- one species makes area habitable for other species Inhibition- early species hinder growth of later species Tolerance- late successional species are unaffected by earlier species Study of how populations change in SIZE, DENSITY, and AGE DISTRIBUTION Clumping Most populations live in clumps Why live in clumps? Resources vary from place to place Living in a herd/ flock/ school provides protection from predators Predators are almost guaranteed a meal Some form temporary groups for mating purposes Uniform- allows species to maximize limited resources Random- very few species are randomly distributed What four factors determine change in population size? Hint: pop change= (? + ?) – (? + ?) Pre-reproductive Reproductive Post-reproductive Remember the population pyramids? Intrinsic rate of increase (r) Rate a population would grow at if it had unlimited resources Biotic potential Capacity for growth Environmental conditions within species range of tolerance Generalists Easily adapt to change Resistance to disease and predators Enough food Ability to migrate and live in other areas Individuals: Reproduce early Reproduce often Have a lot of babies each time Have short generation times Populations cannot grow indefinitely Environmental resistance- all the factors that act to control population growth Environmental conditions outside of range of tolerance Low reproductive rate Specialists Not enough food/ resources Too many predators/ competition Unsuitable habitat Unable to change K Maximum number of individuals of a given species that can be sustained indefinitely in a given space Growth slows down as population reaches K Population grows at a fixed rate Grows slowly at first then growth explodes Creates a J-shaped population graph Rapid exponential population growth followed by decline until population levels off What happens when growth exceeds K? Overshoot- happens when population exceeds K Due to a reproductive time lag Birth rate must fall and death rate must rise Dieback or crash UNLESS organisms can change to another resource Density- INDEPENDENT population controls Affect population size regardless of density Floods, fires, freezes, hurricanes, tornadoes, pollution, habitat destruction, pest control Density-DEPENDENT population controls Greater effect with higher density Competition, predation, parasitism, and infectious disease EX: Black Plague in Europe & Citrus canker Stable Size population size fluctuates only slightly above and below carrying capacity Ex: species found in rain forests Irruptive Short period of explosive growth Followed by a crash Short-lived, rapid reproducers Ex: seasonal bugs Cyclic Have fluctuations periods of up and down over a longer amount of time Lemmings 3-4 year cycles Lynx and snowshoe hares 10 year cycles Irregular No patterns distinct pattern Not really understood why Only 1 organism needed Offspring are exact genetic clones Usually smaller, simpler, singlecelled organisms Budding, binary fission 97% of organisms Need 2 organisms Sex cells (gametes) combine to create one new, genetically unique organism with DNA from both parents Men don’t give birth. Women must produce 2 kids to replace both parents. Increased chance of genetic defects during meiosis Courtship & mating rituals can be time consuming and dangerous Genetic diversity is an advantage when environments change Males can gather food and protect the women and children 2 types Depends on where you find them on the S-shaped population curve Basic characteristics of reproduction Have capacity for high-rate of pop increase (r) Reproduce early Make lots of eggs/ have lots of babies Little to no parental care Produce so many to ensure some survive Ex: bugs, algae, bacteria,rodents Tend to be opportunists Able to take over after a disturbance Can easily crash Reproduce later in life Few babies that develop inside mom Live longer Born large, develop slowly Parental care until they reach reproductive age Called K-selected because they do well in competition near their carrying capacity Typically follow logistic growth Prone to extinction Most mammals, birds of prey, and large/ long lived plants Individuals tend to have different life expectancies Can show this on a survivorship curve 100 Percentage surviving (log scale) Late Loss 10 1 0 Early Loss 0.01 Age Percentage surviving (log scale) 100 10 1 0 Early Loss: Survivorship is low early in life, lots of babies die, only a few adults age and make it through adulthood 0.01 Age Percentage surviving (log scale) 100 10 Constant Loss: constant death rate among all ages Ex: song birds 1 0 0.01 Age Percentage surviving (log scale) 100 10 1 Late Loss: High survivorship to a certain age then very high mortality 0 0.01 Age Founder Genetic effect: diversity is limited when a few individuals colonize a new habitat Geographically isolated from old pop Demographic Only bottleneck: a few individuals survive a catastrophic disturbance like a hurricane or human disturbances (hunting, deforestation) Genetic drift: Random changes in gene frequencies that allow certain individuals to breed more which makes their genes more dominant Inbreeding: Individuals in a very small pop breed with each other Can increase frequency of defective genes