Ecology-Option G IB Biology 2 Van Roekel

G.1 – Community Ecology G.1.1 Outline the factors that affect the distribution of plant species, including temperature, water, light, soil pH, salinity and mineral nutrients. G.1.2 Explain the factors that affect the distribution of animal species, including temperature, water, breeding sites, food supply and territory. G.1.3 Describe one method of random sampling, based on quadrat methods, that is used to compare the population size of two plant or two animal species. G.1.4 Outline the use of a transect to correlate the distribution of plant or animal species with an abiotic variable. G.1.5 Explain what is meant by the niche concept, including an organism’s spatial habitat, its feeding activities and its interactions with other species. G.1.6 Outline the following interactions between species, giving two examples of each: competition, herbivory, predation, parasitism and mutualism. G.1.7 Explain the principle of competitive exclusion. G.1.8 Distinguish between fundamental and realized niches. G.1.9 Define biomass. G.1.10 Describe one method for the measurement of biomass of different trophic levels in an ecosystem.

What is a community? Community - A group of interdependent organisms, or different populations, living and interacting with each other in the same habitat. interdependent organisms habitat Distribution of organisms is affected by abiotic and biotic factors

Factors Affecting Distribution of Plant Species Temperature Water Light Soil pH Salinity Mineral Nutrients

Temperature & Water Foredune: High temps, little water  less variety of plants – Marram Grass: long roots, long narrow leaves that curl, both features help find/save water and resist heat Mature Dune: Cooler temps, moist condition  numerous variety of plants – Ferns: survive in low temps and moist conditions

Light Marram grass requires constant sunlight, found in sunny areas of dune – Long narrow leaves reduce water loss, poor ability to capture sunlight Ferns found in shady areas of mature dune – Wide leaves captures small amount of light

Marram Grass & Ferns

Soil pH Soil pH changes in different locations, allows for different plant life – Marram grass in pH of 7.5 of Foredune & Yellow Dune – Grey Dunes have lower, more acidic pH, Heather plants thrive here

Salinity Foredunes catch salt spray from ocean – Marram grass and Lyme grass can live in salty environments Grey dunes as less salty – Shrubs, mosses, and lichens live here

Mineral Nutrients Mineral nutrients refer to the minerals and nutrients found in the soil – Mature dunes contain the most because soil has been building up for hundreds of years, support large trees and variety of organisms – Grey dunes contain some mineral nutrients supports small shrubs, mosses, and lichens – Foredune and yellow dunes contain little mineral nutrients

Factors affecting distribution of animal species Temperature Water Breeding sites Food Supplies Territory -

Temperature Animals have different adaptations to live in hot and cold environments – Sand Wolf Spider: lives in foredune, can survive hot temps by burrowing in sand – Woodland Spider: lives in mature dune, can survive cooler temps, but would die in foredune

Water Animals can be specifically adapted to live in wetlands – Necessary for survival: laying eggs, food, etc.. – Blue Heron hunts in wetlands Animals do not need wetlands/abundance of water for survival – Woodpeckers, found in mature dunes and eat insects living in trees

Breeding Sites Wetlands necessary for Blue Heron to breed – Food source – Protection from sun and wind Mature Dunes and trees necessary for woodpeckers to breed – Branches used for nesting sites – Food source

Food Supply Some animals adapt to feed on specific food, others are more wide-ranging and can travel to find variety of food sources – Raccoons go anywhere on dune where food is – Rabbits build burrows in foredune and live near Marram grass, which they eat

Territory Some animals live in specific areas and remain separated from each other – Use variety of mechanisms to mark territory – Coyotes mark territory by urination, which separates different groups of coyotes – Studies have shown that territories do not overlap

Random Sampling Used to compare populations of different species in a community Take a random sample and use it to estimate total number of organisms Samples must come from all around habitat KEY TERM: Random Sample – each organism has an equal chance of being selected for the count

Quadrat Method Quadrat method – – Map entire area (dune example) – Determine size of the quadrats – Place a grid with numbers around entire area – Choose which squares to use to make sample – Count number of “whatever” in sample quadrant – Count number of “whatever else” – Calculated averages of each then multiply average by total number of quadrants

Transect Method Most commonly used for studying how the distribution of plants in an ecosytstem is affected by abiotic factors Looking at Sand Dunes, dunes nearest sea are youngest, dunes farthest inland are oldest

Transect Method Right angle from sea, lay tape all they way up the dunes Ever meters, mark out a quadrat Identify and could plant species of interest in each quadrat Measure abiotic features (temp, light, etc…) Determine pattern of distribution from youngest to oldest dune and examine correlations

The Niche Concept Organisms have particular roles, or niches, in their ecosystem The niche concept includes: – Spatial Habitat: where the organism lives, every organism has a particular space in the ecosystem that is its spatial habitat – Feeding Activities: What an organism eats affects the ecosystem by keeping other populations in check – Interactions w/ others: Include competition, herbivory, predation, parasitism, and mutualism

Interactions between Species Competition: Occurs when two species rely on the same limited resource in an ecosystem 1 species will be better adapted than the other to benefit from resource – Coyotes and Red foxes both eat small rodents and bird. Expanded farming has led to overlapping environments and more competition between the two – Natterjack toad (Bufo calamita) competes with the common toad (Bufo bufo) for resources in coastal dunes in the UK

Interactions between Species Herbivory: occurs when a herbivore (primary consumer) feeds on a producer (plants). Interaction between plants and animals: – Rabbits eat Marrum Grass – Monarch butterfly larvae eat leaves of milkweed plant

Interactions between Species Predation: predator (consumer) eats another consumer. Interaction between two animals, the predator and the prey, each of which affects the other – Canadian Lynx preys on arctic hare, changes in numbers of either population are followed by changes in the other – Blue Heron is a predator on frogs

Interactions between Species Parasitism: occurs when one organism lives on or in a host and depends on the host for food. The host is harmed by parasite – Plasmodium is a parasite that causes malaria in humans. Reproduces in liver and red blood cells and uses mosquitos as vectors to transmit from humans to humans – Leeches are parasites in ponds that puncture the skin of host and secrete an enzyme that prevents clotting. Hosts are humans or other mammals.

Interactions between Species Mutualism: occurs when both organisms benefit from the relationship – Lichens (fungi) have mutualistic relationships with algae. Algae photosynthesize and make carbohydrates, fungi absorb mineral ions needed by algae – Rhizobium is a nitrogen fixing bacteria that lives in the roots of leguminous plants such as beans and peas. Bacteria fixes nitrogen that the plant uses to make proteins, the plant makes carbohydrates that bacteria use for food

Mutualism Clownfish and sea anemones live together. Clownfish live in area of tentacles of poisonous anemone. Clownfish is covered with mucus that protects from sting of anemone and lure other fish to tentacles of anemone. Clownfish eat remains of fish and nibble off remains of dead sea anemone tentacles

The Principle of Competitive Exclusion States that no two species in a community can occupy the same niche When two species have a similar need for the same resources, one will be excluded One species will die out and the other will survive

The Principle of Competitive Exclusion Demonstrated by Russian ecologist G.F. Gause in 1934 Use 2 species of paramecium, P. aurelia and P. caudatum – When two were kept separate both survived equally well – When in the same culture, P. caudatum died out and P. aurelia survived – P. aurelia out-competed P. caudatum

Fundamental and Realized Niche Fundamental Niche: the potential mode of existence, given the adaptations of a species Realized Niche: the actual mode of existence, which results from adaptations and competition with other species Red Fox fundamental niche is the edge of a forest and all organisms it interacts with. Its realized niche is narrower because of the disappearing forests and differing species, as well as increased competition

Biomass Biomass: the total mass of organic matter, with consists of compounds such as carbs, lipids, and proteins Measured as dry mass of organic matter of living organisms in grams per meter squared per year [(g * m -2 )/ y]

Measuring Biomass Measure total area of ecosystem Divide are into small plots Choose one plot to sample Measure size of each plant species (height and diameter) including trees and low growing vegetation. Cut down all vegetation on that plot. Dry all samples in drying oven Use mathematical model to show relationship between each plant species and its biomass Sample other plots by measuring size and height of plants Apply mathematical formula to find biomass Set traps for animals in plot to weigh and measure organisms Use tables to determine their biomass Average data for all species per plot Multiply average per plot by number of plots Repeat seasonally or yearly to study changes in a community over time