S3 BGE BIOLOGY Part 1 BIODIVERSITY1G: Interdependence-Niche & Biotic Factors

You will study the following topic at Level’s 4 & 5. A. Biodiversity, Ecosystems & Investigating Abiotic Factors (L3/4/5) B. Biomes (L4/N4) C. Investigating Distribution of Organisms: Sampling Techniques (L3/4/5) D. Identifying Organisms which have been Collected: Keys (L3/5) E. Interdependence, Food Chains & Webs (L4/5) F. Energy in Ecosystems - Pyramids (L5) G. Interdependence -Niche & Biotic factors (L4/5)H. Impact of Population Growth on Biodiversity (L4/5)I. Impact of Natural Hazards on Biodiversity (L4)J. Conservation of Endangered Species (L4)

Interdependence: Niche & Biotic Factors Learning OutcomesL4 Learning Outcomes: You should be able to…o Describe the niche of an organismo Describe biotic factors and how they affect living species, these should include

food availability, predators, disease and competition.L5 Learning Outcomes: As well as the above you should be able to…o Know that niche also involves environmental conditions that it can tolerate

such as temperature.o Describe the differences between interspecific and interspecific competition to

include which form of competition is more intense.

(L4/5) DEFINITIONS TO LEARN – MAKE ME A FLASH CARDBiological term

Definition

Interdependen A term used to explain that all living things depend on each other

Level 5 Planet Earth: Biodiversity and interdependence SCN 5-01a; Topical Science SCN 5-20aNational 5: Unit 3: Key Area 3.1c Ecosystems

Key Area 3.1c: A niche is a role that an organism plays in its community. It involves competition and predation and the conditions it can tolerate such as temperature.

National 5: Unit 3: Key Area 3.1d Ecosystems Competition in ecosystems occurs when resources are in short supply. Interspecific

competition occurs amongst individuals of different species for one of a few resources. Intraspecific competition occurs amongst individuals of the same species and is for all resources required, this is more intense.

National 5: Unit 3: Key Area 3.2e Distributions of Organisms The effect of biotic factors on biodiversity and the distribution of organisms.

Level 4 Planet Earth: Biodiversity and interdependence SCN 4-01a; Topical Science SCN 4-20a Use the term niche correctlyNational 4: Unit 3: Key Area 3.1 Animal and plants species depend on each other. 3.1c Investigate various biotic factors, e.g. food availability, predators, disease & competition

ce for survivalSpecies A group of organisms with similar characteristics and the ability to

interbreed to produce fertile offspring.Community All the organisms living in a habitPopulation The members of a species living in a defined area of habitatNiche The role an organism plays within its communityBiotic Factor A factor related to living aspects of an ecosystem, such as

predation, disease and competitionMigration Seasonal movement of animals from one region to anotherPredation Where an organism, the predator, kills and eats another organism

(prey).Competition Competition happens when resources are in short supply.Intraspecific Competition

Intraspecific competition occurs amongst individuals of the same species and is for all resources required, this is more intense.

Interspecific Competition

Interspecific competition occurs amongst individuals of different species for one of a few resources

(L4/5) NicheEach species has its own ecological niche. This refers to the vital role the species play’s in its ecosystem. The term describes the species’ position in the community and refers to how it survives and reproduces there. It covers its whole way of life, all the interactions it has with the habitat and with other members of the communityIn L5 you must also be aware that an organism’s niche is also it’s ability to tolerate environmental factors (abiotic factors), such as extremes of temperature.

Red grouse in the moorland ecosystemo In the moorland ecosystem the red grouse has

a unique niche.o It feeds on feeds on heather shoots and builds

its nests under the cover of heather.o The grouse is prey for several predators,

including hen harrier and golden eagle.o Its droppings & moulted feathers drop into

soil. They are decomposed to keep the soil fertile.

(L4) Biotic factors for SurvivalLiving things depend on each other within the web of life. Competing for food and avoiding disease or being eaten are each important to the survival of living things.At level 4 there is four biotic factors1. Food2. Predation3. Disease 4. Competition

(L4) Food as a biotic factorThe survival of a population of animals in an ecosystem depends on there being enough food them. The availability of food can depend on the weather in a particular year (mixture of abiotic factors), the time of year and the time of day.

o KNOT: The knot is a wading bird which flock to Britain’s mudflats in winter when food (shellfish and worms) is abundant. However, they can only feed at specific times of the day…when the tide is low.

o BARNICLE GEESE: These birds spend the summer inside the Artic Circle where they can graze on grass during constant daylight while they raise their chicks. During autumn they migrate in huge numbers to Scotland to avoid the severe Artic winder. If they did not do this, they would starve when their food was buried beneath the snow and ice.

(L4) Predation as a biotic factorPredators are animals that catch and eat other animals (their

prey).o LEOPARDS: In Africa, leopards are ambush predators,

and they prey on different species of antelope and gazelle.

o RED DEER: Red deer is Scotland’s largest land mammal, but its population needs to be controlled by ‘culling’ as it no longer has any natural predators. In the days when lynx and wolves lived in Scotland, deer numbers were controlled naturally within the web of life.

(L4) Disease as a biotic factorDiseases that can be caused by bacteria and viruses lead to animals being unable to feed, compete, reproduce and survive. Plants are affected by disease too.

o POTATO BLIGHT: Is caused by a fungus. This was the cause of the Irish Potato Famine, also known as the Great Famine, which took place in Ireland between 1845 and 1852. It caused numerous deaths due to starvation and disease and led to mass emigration from the island

o GRASSES: Plants, such as grasses can are often infected with fungal diseases (e.g. rusts).

o Disease spreads more quickly through overpopulated species.

o Predators often take the opportunity to attack prey which has been weakened by disease.

o TICKS: can pass on disease (e.g. Lymes disease) between wild and domestic animals, or between livestock and humans.

o MYXOMATOSIS: This is a disease of rabbits caused by a type of pox virus. It is passed on by blood-sucking insects, such as fleas, ticks, mites and mosquitoes. It spreads rapidly among wild rabbit populations and can easily be passed on to domestic rabbits.

(L4/L5) Competition as a biotic factorCompetition happens when resources are in short supply.

o Animals compete for food, water shelter and access to mates.

o Plants compete for things they need to grow, light, water, nutrients and space.

(L4 -Basic definition, L5 more detail) There are two types of competition.

1.Interspecific competition.Occurs amongst individuals of different species for one or a few of the resources they require.

RED VERSUS THE GREY SQUIRRELThe introduction of the North American grey squirrel to Britain has resulted in the widespread decline (almost to extinction) of the red squirrel. Both animals occupy the same ecological niche in the woodland ecosystem. The grey squirrel is thought to have become so widely distributed and successful because it competes for food aggressively for food and is be able to make use of a wide variety of foodstuffs including acorns (high in tannins). The grey squirrel is therefore continuing to populate areas at the expense of the red squirrel which is more timid and whose digestive system cannot cope with large quantities of acorns and other seeds rich in tannins.

2.Intraspecific competition.Occurs amongst individuals of the same species and for ALL resources required. (L5) Intraspecific competition is therefore more intense than interspecific competition.

ROBINS: Territorial behaviourIntraspecific competition in animals often happens due the animal being territorial. Members of the same species fight for territory; this behaviour is specifically common in birds like the Robin. The male Robin will establish and live in a small area which contains enough food for himself and eventually for a mate and their young. Robins are one of only a few bird species that hold their territory all year round - males do not migrate in the winter. The use a high-pitched song and puff out their red breast initially to warn other robins off. Failing that a male robin will violently attack another robin, pecking it viciously and flapping wings vigorously against it.

(L5) Evolutionary effect of intraspecific competitionIntraspecific competition regulates the size of the population of the species affected. The weaker members are weeded out by NATURAL SELECTION. (Covered later in this unit!)