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 22nd – C-D, 23rd 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 22nd – C-D, 23rd 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 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 Growth rate slows as the population increases Can reduce the number of offspring born
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. Mates are difficult to find since there are so few individuals Population usually does not survive; especially harmful to threatened species
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 Population can cope with variations in natality and mortality, as well as environmental changes or disasters Population maintains enough genetic variation amongst its members
Density-Independent Factors Play a role in limiting population growth regardless of population size Ex. extreme weather, human intervention Ex. Thrips (insect) have lower reproductive success at lower temperatures Insecticide application (can result in death directly or through biomagnification)
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 22nd/ 23rd
Review Density-Dependent Factors Allee Effect Intraspecific competition Predation Disease Allee Effect Minimum viable population size Density-Independent Factors Limiting Factor 1.)Play a greater role in limiting population growth as the population increases in size Ex. competition, predation, disease 2.) When the individuals of a population of the same species compete for the same resources 3.)A predator catches, kills and consumes prey (of another species). Helps to regulate the number of prey 4.)In dense or overcrowded populations, pathogens are able to pass more easily from host to host 5.) When the population density is so low that the species cannot reproduce. 6.) Play a role in limiting population growth regardless of population size Ex. extreme weather, human intervention 7.) The smallest number of individuals needed to ensure a population can continue for a given period of time 8.) 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
Using your textbook (P. g 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
Interspecific competition 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 Ex. bacteria in our intestinal tract (they get nutrients from the food we consume and produce vitamins that we need) Ex. pollination (insects and animals ingest pollen/nectar, and pollen stuck to bodies of insects and animals gets spread to other flowers)
Interactions Within Communities Commensalism (+/0) One organism benefits and the other organism is unaffected Ex. remora (small fish) attach themselves to sharks and feed on small pieces of the shark’s prey and get free transportation
Host is harmed but is usually not killed 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 Ex. Plasmodium (malaria), tapeworms, fleas, lice Social parasite: manipulates the social behaviour of their hosts to complete their life cycle (ex. cowbirds use nests of smaller birds and these smaller bird newborns are usually killed)
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 One species may change its behaviour so that it survives on different resources Individuals of one population may migrate to another habitat where resources are more plentiful
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 Ex. Anolis lizards partition their tree habitats by occupying different perching sites Ex. plants differing in their root systems to allow them to acquire water and mineral ions from the same environment
Interactions Within Communities Predation interspecific interaction If other prey is available, it alters this cyclical relationship Population density of one species (predator) increases while the population density of the other species (prey) decreases
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 Ex. European rabbit in Australia (page 686) Ex. West Nile virus (from Uganda) is believed to have been introduced into North America accidently via an exotic frog species
Complete pages 10 – 11 in your population ecology package.