Biology 2.6 - Ecology “The study of how organisms interact with each other and their physical environment”
Definitions • Biosphere: The area (on Earth) where life is found • Species: Organisms with similar characteristics that are able to interbreed to produce fertile offspring. eg cockles • Population: A group of organisms of the same species that live in the same area at the same time. eg mud crabs at Warrington • Community: All the populations of different species living and interacting in an area. eg bush community at Ross Creek • Ecosystem: A community and the environment that it is found in. eg a mudflat ecosystem • Biotic: The living factors of an environment. eg food supply • Abiotic: The non-living factors of an environment. eg rainfall • Habitat: The place where an organism lives. eg rock pools
Biosphere The area (on Earth) where life is found - ocean floor to upper atmosphere
Species • Organisms with similar characteristics that are able to interbreed to produce fertile offspring. eg cockles Austrovenus stutchburyi
Male Donkey Female Horse Mule (sterile)
Male horse Hinny (sterile) Mule vs Hinny Mule more common “equine hybrid is easier to obtain when the lower chromosome count, the donkey, is in the male” - Wikipedia Hinny smaller (due to smaller donkey uterus?), mane & head different… no difference also argued. Female donkey
Population • A group of organisms of the same species that live in the same area at the same time. eg barnacles at St Clair
Community • All the populations of different species living and interacting in an area. eg bush community at Ross Creek Ecosystem • A community and the environment that it is found in. eg a mudflat ecosystem
Environmental Factors Biotic Factors - The living factors of an environment. eg food supply Organisms affect each other as: • Parasites • Pathogens • Symbionts • Predators • Herbivores • Competitors • Food supply…………..
Environmental Factors Abiotic Factors - The non-living factors of an environment. eg temperature Also: • Rainfall • Humidity • pH • Salinity • Light intensity………..
Environmental Factors on a Blue Cod Competition Wave action Predators Food supply Dissolved oxygen parasites Human influence Water temperature salinity pH
Biotic Abiotic Environmental Factors in a Rock Pool
Abiotic (Physical) Factors of soil in the School Garden: • Temperature • Moisture • Salinity • pH • Soil profile • Infiltration • Aeration • Soil fertility • Soil particle size, organic matter content, microbes, density, minerals
Physical Gradients • Most abiotic factors change with distance across an environment (this creates different habitats and microclimates)
Habitat • The place where an organism lives. eg rock pools Habitat is defined by the abiotic and biotic factors found there
Forest Floor Biotic: Feed on dead wood Abiotic: Cool temps Moist soil High humidity Wood Ear Fungus Habitat
Liebig’s Law of the Minimum* “In most habitats there is one factor that determines how a species is distributed. This is the Limiting Factor and determines the distribution and numbers of a species” Eg, in the outback the number of plants and how close they are is related to availability of water
Activity • Nocturnal – active at night. eg morepork • Diurnal – active during day. eg sheep • Crepuscular – active at dawn/dusk. eg rabbit
Feeding • Producer (autotroph): organism that makes own food, usually photosynthetic (usually plants, algae, some bacteria). • Consumer (heterotroph): feeds on other organisms or dead matter. • Carnivore: consumes animals. Wolf • Herbivore: consumes producers. Sheep • Omnivore: consumes producers & animals. Possum • Scavenger: consumes (large) dead organic matter Slater, Worm, Crab • Decomposer or Detritivore or Saprophyte: breaks down dead organic matter (more completely than scavengers). Fungi, Bacteria
Adaptations Inherited features that help an organism to survive in its habitat !Different to adapting – this means getting used to environment (eg your hairs stand on end when you are cold) • Structural: physical structures. eg Waxy cuticle on leaves reduces water loss • Physiological (functional): processes an organism carries out. eg Intestinal cells secrete enzymes to digest food. • Behavioural: the way an organism acts (individually or corporately). eg Spiders spin web to catch food.
Adaptations of a Rabbit S: widely spaced eyes S: powerful hind legs P: High reproductive rate P: Short gestation P: Many young in a litter B: Freezes when startled B: Stamps feet when startled
Ecological Niche • The ‘functional position’ of an organism in its environment • Ecological Niche Includes: • Habitat • Feeding type • Activity times • Adaptations ?
Sealion Ecological Niche • Feeding Type: Carnivore • Activity: Diurnal • Habitat: Coastal marine • Adaptations: Fast swimmer, tolerates cold water…..
Slater (Porcellio scaber)Ecological Niche(from research and experiments) • Habitat • Biotic • Abiotic • Feeding type • Activity • Adaptations • Physiological • Structural • Behavioural
Slater Adaptations Behavioural • Clumping • Avoid light • Curls when touched • Freezes when touch Physiological • Excrete ammonia • Aerobic respiration • Cold blooded (ectothermic) • Haemolymph (blood) can carry oxygen • Dozens of young Structural • Hard Exoskeleton • Jointed, flexible exoskeleton • Many legs • Dark slater • Oval, thin shape • Gills • Antennae • Hooks on legs • Excrete directly thru exoskeleton • Uropods (two feet at back) take up water
Task: Describe a Plant’s Niche • Choose a plant from the school grounds. • Name it, describe it’s ecological niche • Habitat • Include the abiotic and biotic factors found there and measure them or describe them • Feeding • Adaptations • At least 1 structural, physiological, behavioural… Hebe Rhododendron
Task: Ecological Niche Poster • Pick an organism • Name it, describe it’s ecological niche by giving its: • Habitat • Include the abiotic and biotic factors found there and measure them or describe them • Feeding type / method • Activity times • Adaptations • At least 1 structural, physiological, behavioural… • Include 1 captioned picture Type your name. Print to colour, print enlarge to A3 by: click printer properties, paper, tick both print on a3 AND fit to print size. Best posters go to the pool room
Tolerance For each abiotic factor (eg pH) each organism has the following: • Optimum Range: where it functions best • Tolerance Range: where it survives • Zone of Stress: processes (eg respiration affected) • Zone of Death: must move on or die!
Gause’s Principle “Organisms occupying the same niche cannot co-exist because they compete for the same resources” Eg flax caterpillars Georgii Frantsevich Gause 1910–1986
Flax looper Nocturnal feeder Scrapes off flax, near midrib (leaves translucent ‘windows’ Flax notch Nocturnal feeder Bite off edge of flax (leaves notches) Gause’s Principle eg Flax Caterpillars
Gause’s Principle “Organisms occupying the same niche cannot co-exist because they compete for the same resources” Aka – Competitive Exclusion Principle Eg flax caterpillars – at first seem to be in direct competition, but actually occupy slightly different habitats.
Testing Gause’s Principle • Aim: to determine if flax looper and notch caterpillars do occupy different microhabitats • Hypothesis: I predict that the caterpillars do/not occupy different microhabitats • Equipment: flax leaves with evidence of both caterpillars, ruler • Method: • 1. Measure distance from mid rib of leave to middle of each feeding location. • 2. Record as either looper or notch. • 3. Collate class data, analyse
Results Conclusions The results show… because…
Niche Size… • The full range of environmental conditions an organism can live in is the fundamental niche • But, because it faces competition from other organisms it has to occupy a narrower set of conditions (to which it is best adapted). This is the realised niche (kite graph OHT)
Population Features Population: a group of organisms of the same species living in the same area at the same time
Features of Populations • Density • Distribution • Population Size • Migration • Sex ratios • Population Fertility • Age Structure • Population Growth Rate • Natality • Mortality
Population Size • Number of organisms in population (abundance) • How many penguins in the picture…? • Direct Count • Sampling • Mark & Recapture
Population Density • Number of organisms per unit area Low: territorial? solitary? High: colonial? social?
Population Distribution • Clumped – around resource, protection • Uniform – evenly spaced • Random – no pattern (plants, rare in animals)
Migration • Immigration – individuals entering population • Emigration – individuals leaving population • Both can affect: density + distribution, sex ratio, pop fertility, age structure (Immigration – IN, Emigration – EXit)