# FACTORS AFFECTING DISTRIBUTION OF POPULATIONS. Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation.

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FACTORS AFFECTING DISTRIBUTION OF POPULATIONS

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. - Think about your own tolerance to temperature. For 3 mins, ask your neighbour what you think you would do in -1 degrees, 22 degrees, 30 degrees, and 35+ degrees.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. Same as before, discuss with your neighbour this situation: You have two fish tanks with four fish in each. In one tank you add a tablespoon of salt every day. What would happen?

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. 3. Geographical barrier: Simple – the populations can’t get there.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. 3. Geographical barrier: Simple – the populations can’t get there. Discuss some geographical barriers for populations.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. 3. Geographical barrier: Simple – the populations can’t get there. 4. Leibig’s law: Whatever essential environmental factor is present in the least favourable amount.

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. 3. Geographical barrier: Simple – the populations can’t get there. 4. Leibig’s law: Whatever essential environmental factor is present in the least favourable amount. What could this mean?

Factors affecting the distribution of populations 1. Tolerance: An organism’s ability to survive variation in environmental conditions. Death / Lower limit of tolerance / Physiological Stress / Optimum / Physiologcial Stress /Upper limit of tolerance / Death 2. Acclimation: change in tolerance if change is slow. 3. Geographical barrier: Simple – the populations can’t get there. 4. Leibig’s law: Whatever essential environmental factor is present in the least favourable amount. - Eg. Farms around here = cattle got ‘bush sickness’ because they were lacking an essential mineral – cobalt. Now they flourish.

Controls on a population  Abiotic -

Controls on a population  Abiotic – droughts, fire, flood, storms, pesticides etc.

Controls on a population  Abiotic – droughts, fire, flood, storms, pesticides etc. Density-independent =

Controls on a population  Abiotic – droughts, fire, flood, storms, pesticides etc. Density-independent = A fire will burn trees whether there are few or many. Density-dependent = space, water and substrate where the organism lives. Dependent because

Controls on a population  Abiotic – droughts, fire, flood, storms, pesticides etc. Density-independent = A fire will burn trees whether there are few or many. Density-dependent = space, water and substrate where the organism lives. Dependent because if there is a limited amount of space, there will be a limited number of organisms.

Controls on a population  Biotic -

Controls on a population  Biotic – living influences. Members of same species, members of another species.

Controls on a population  Biotic – living influences. Members of same species, members of another species. Density-dependent = hit harder when pop. numbers are high.

Controls on a population  Biotic – living influences. Members of same species, members of another species. Density-dependent = hit harder when pop. numbers are high. EG?

Regulating factors  What are some regulating facts on a population?

Regulating factors  Competition with species for limited resource:

Regulating factors  Competition with species for limited resource: same species = same requirements from environment.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food:

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space:

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year. Not fully understood, but can cause stress syndrome – lack of hormones released when crowded and reproductive organs can shrink and become useless....

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories:

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories: Spreads population out.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories: Spreads population out. Strongest = best territory.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories: Spreads population out. Strongest = best territory. No territory = no mating.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories: Spreads population out. Strongest = best territory. No territory = no mating. Heirachies = pecking order – top gets best food, shelter and mates. Ensures best genes mate with best genes.

Regulating factors  Competition with species for limited resource: same species = same requirements from environment. Survival of the fittest – best competitors for resource. This is INTRASPECIFIC competition.  Lack of food: limits re-productivity. EG. Flour beetles become cannibals!  Lack of space: Crowding – plants don’t grow well. EG. Gannets – No space = no breeding that year.  Territories: Spreads population out. Strongest = best territory. No territory = no mating. Heirachies = pecking order – top gets best food, shelter and mates. Ensures best genes mate with best genes.

Regulating Factors  Self-poisoning:

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out! Interesting: Fungi produce penicillin which kills bacteria, but it also slows down the fungi’s growth rate.

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out! Probably MORE interesting: yeast produce ethanol. However yeast will stop growing when the alcohol reaches 12% (wine). If CO2 is not allowed to escape, the yeasts are poisoned = homemade ginger beer is fizzy, but not very alcoholic.

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!  Disease:

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!  Disease: Closer animals are to eachother, easier it is for disease to spread.

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!  Disease: Closer animals are to eachother, easier it is for disease to spread. Also, high population = more potential for range of disease. (EG. Super bug / human population too big?)

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!  Disease: Closer animals are to eachother, easier it is for disease to spread. Also, high population = more potential for range of disease.  Parasitism:

Regulating Factors  Self-poisoning: bacteria. Wastes accumulate and kill before the food runs out!  Disease: Closer animals are to eachother, easier it is for disease to spread. Also, high population = more potential for range of disease.  Parasitism: Live off host, but don’t kill them = keep numbers in check.

Competition between dif. species  Usually results in

Competition between dif. species  Usually results in one population getting less until it DIES!

Competition between dif. species  Usually results in one population getting less until it DIES!  This is all to do with the Gause principle (we did this a few lessons ago)  Predation:

Competition between dif. species  Usually results in one population getting less until it DIES!  This is all to do with the Gause principle (we did this a few lessons ago)  Predation: if prey species rise, so do predator species. Makes sense!

Competition between dif. species  Usually results in one population getting less until it DIES!  This is all to do with the Gause principle (we did this a few lessons ago)  Predation: if prey species rise, so do predator species. More predators = less prey. This in turn lets the prey’s food source to recover (EG – more foxes = less rabbits = more grasses/plants)

Competition between dif. species  Usually results in one population getting less until it DIES!  This is all to do with the Gause principle (we did this a few lessons ago)  Predation: if prey species rise, so do predator species. More predators = less prey. This in turn lets the prey’s food source to recover (EG – more foxes = less rabbits = more grasses/plants) Then, the predators can decrease too if there is less prey.

Competition between dif. species  Usually results in one population getting less until it DIES!  This is all to do with the Gause principle (we did this a few lessons ago)  Predation: if prey species rise, so do predator species. More predators = less prey. This in turn lets the prey’s food source to recover (EG – more foxes = less rabbits = more grasses/plants) Then, the predators can decrease too if there is less prey.

Something to think about  In nature, parasites don’t kill their host, and predators don’t ‘wipe out’ the prey population.

Something to think about  In nature, parasites don’t kill their host, and predators don’t ‘wipe out’ the prey population.  Humans break all the laws when it comes to predator-prey relationships – we hunt things to near extinction (and in the past, actual extinction).

Something to think about  In nature, parasites don’t kill their host, and predators don’t ‘wipe out’ the prey population.  Humans break all the laws when it comes to predator-prey relationships – we hunt things to near extinction (and in the past, actual extinction).  EG. Whaling. There is little or no risk to the humans who hunt whales, yet the whale has certain death.

Something to think about  In nature, parasites don’t kill their host, and predators don’t ‘wipe out’ the prey population.  Humans break all the laws when it comes to predator-prey relationships – we hunt things to near extinction (and in the past, actual extinction).  EG. Whaling. There is little or no risk to the humans who hunt whales, yet the whale has certain death.  How is this fair in the balance of nature?

Emigration  Population can be reduced if some of the animals leave.

Emigration  Population can be reduced if some of the animals leave.  May be due to lack of food, crowds, too much competition.

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