REVIEW Carrying capacity Population dynamics Fecundity Biotic potential

REVIEW • Carrying capacity • Population dynamics • Fecundity • Biotic potential • Calculating Population change • Open population • Closed population • Three general survivorship patterns • 3 growth models

• Date of next test • May 22 nd – C-D, 23 rd A-B

Pike Perch game answers • 1. ) Graph

• 2. ) Since pike eat a lot of perch there needs to be many more perch than pike in order for the pike to survive. • 3. ) The pike population responds to the population of perch. This means that an increase in perch population will cause an increase in pike populations and vice versa.

• 4. ) If there are no predators, the prey’s population would continue to increase until they run out of food or die from stress due to over-crowding or disease • 5. ) Predators are beneficial to prey because they can help control its population and prevent disease or over-crowding.

• Read through population dynamics graphs and complete it.

Some key words used to describe population graphs • S Curve (Sigmoid) / logistic growth – Lag Phase – Log phase – Stationary phase/ Equilibrium • • Exponential growth Limiting factors Density dependent/independent Carrying capacity

• Date of next test • May 22 nd – C-D, 23 rd A-B

REVIEW • Carrying capacity • Population dynamics • Fecundity • Biotic potential • Calculating Population change • Open population • Closed population • Three general survivorship patterns • 3 growth models

Factors Affecting Population Change & Interactions Within Communities

Density-Dependent Factors • Density-Dependent Factors – Play a greater role in limiting population growth as the population increases in size – Ex. competition, predation, disease

• Intraspecific competition – When the individuals of a population of the same species compete for the same resources

Density-Dependent Factors: • Predation – A predator catches, kills and consumes prey (of another species). • Helps to regulate the number of prey

Density-Dependent Factors • Disease – In dense or overcrowded populations, pathogens are able to pass more easily from host to host

Density-Dependent Factors • Allee Effect – When the population density is so low that the species cannot reproduce.

Density-Dependent Factors • Minimum viable population size – The smallest number of individuals needed to ensure a population can continue for a given period of time

Density-Independent Factors • Density-Independent Factors – Play a role in limiting population growth regardless of population size – Ex. extreme weather, human intervention

Density-Independent Factors • Limiting Factor – Any essential resource that is in short supply or unavailable – Determines how much the individual or population can grow (affects the biotic potential) – Ex. light, space, water, nutrients

• Complete p. g. 9 and first part of 10.

• Bring laptops next class. • Test May 22 nd/ 23 rd

Review • Density-Dependent Factors – Intraspecific competition – Predation – Disease • • Allee Effect Minimum viable population size Density-Independent Factors Limiting Factor

• Using your textbook (P. g. 675 -684) and classmates help, come up with definitions to the following words for your notes.

Interactions Within Communities • • • Community Interspecific competition Ecological Niche Fundamental Niche Realized Niche Symbiosis

• Community – Made up of all populations of different species within an ecosystem • Interspecific competition – When the individuals of different species compete for the same resources – Restricts population growth – A driving force for populations of species to evolve adaptations to continue to use resources

• Ecological Niche (organism’s “occupation”) – An organism’s biological characteristics, including the use of, and interaction with abiotic and biotic resources in its environment • Fundamental Niche – An organism’s biological characteristics and the set of resources individuals in the population are theoretically capable of using under ideal conditions • Ex. If resources were abundant and no competition existed • Realized Niche – An organism’s biological characteristics and the set of resources individuals in the population actually use under existing environmental conditions

• Symbiosis – Two species maintain a close, usually physical association – At least one of the species benefits – Includes mutualism, commensalism and parasitism

Interactions Within Communities • Types of Symbiotic Relationships: – Mutualism (+/+) • Both organisms benefit • Neither organism is harmed • Obligatory mutualism: neither species can survive without the other

Interactions Within Communities – Commensalism (+/0) • One organism benefits and the other organism is unaffected

– Parasitism (+/-) • One organism (parasite) benefits at the expense of the other organism (host) • Host is harmed but is usually not killed • ~1/4 animal species is thought to be a parasite

• Symbiosis worksheet

Interactions Within Communities • Types of Interspecific Competition – I. Interference competition: fighting over shared resources

• II. Exploitative competition: consumption of shared resources

Interactions Within Communities • Interspecific Competition – Niche overlap means more competition. – Competition declines because: • Population size of the weaker competitor declines • One species may adapt. • Migration

Interactions Within Communities • Resource partitioning – Avoidance of, or reduction in, competition for similar resources by individuals of different species occupying different non-overlapping ecological niches – Ex. Anolis lizards – Ex. plants

Interactions Within Communities • Predation – interspecific interaction If other prey is available, it alters this cyclical relationship

Interactions Within Communities • Canadian lynx-snowshoe hare cycle (10 years)

• Complete first ½ of p. g. 10, matching

Defense Mechanisms

Interactions Within Communities • Defence Mechanisms – Plants: morphological defences (thorns, hooks, spines, needles) and chemical defences (distasteful, toxic) – Insects: some use chemicals produced by their food as protection from their predators (ex. monarch butterfly)

Interactions Within Communities • Passive Defence Mechanisms – Ex. Hiding – Ex. Camouflage – Ex. Visual warning to predators of chemical defences (poisons) – Ex. Mimicry • Batesian: a harmless species mimics a harmful species

Interactions Within Communities • Active Defence Mechanisms – Ex. Fleeing from predators – Ex. Alarm calls – More costly in terms of energy required

Interactions Within Communities • Introduction of Exotic (non-indigenous) Species – Can disrupt ecosystems’ dynamic equilibrium and displace indigenous species to such a degree that they impact on the biodiversity in that ecosystem – Since non-indigenous species often have few predators in that area, they can reduce or eliminate indigenous species by outcompeting them for food and habitat, or by preying on them

• Complete pages 10 – 11 in your population ecology package.