C.1 Species and communities Flashcards
What is a limiting factor?
A component of an ecosystem which limits the distribution or numbers of a population
What does a limiting factor define?
Optimal survival conditions according to its effect on a species when in deficiency or excess
What are the two types of limiting factors?
Biotic or abiotic
What do abiotic factors include?
Interactions between organisms
What do biotic factors include?
Environmental conditions
What is the law of tolerance?
Populations have optimal survival conditions within critical minimal and maximal thresholds
What happens as a population is exposed to the extremes of a particular limiting factor?
The rates of survival begin to drop
What are the three regions of the distribution of a species in response to a limiting factor?
Optimal zone
Zones of stress
Zones of intolerance
How is the distribution of a species in response to a limiting factor represented?
As a bell shaped curve with 3 regions
What is the optimal zone?
Central portion of curve which has conditions that favour maximal reproductive success and survivability
What is the zones of stress?
Regions flanking the optimal zone, where organisms can survive but with reduced reproductive success
What is the zones of intolerance?
Outermost regions in which organisms cannot survive
What do the zones of intolerance represent?
Extremes of the limiting factor
What are glycophytes?
Plant species that are not particularly salt tolerant
What does plant growth vary greatly in response to?
Concentrations of salt within the soil
What are halophytes?
Plant species that are salt tolerant
Are most types of plant species glycophytes or halophytes?
Glycophytes
What does the cultivation of land for agriculture cause? (salt concs)
The water table to rise and concentrates salt at the the roots
How does salt concentrating at the roots affect glycophytes?
It makes it harder to extract water from the soil
What is critically important for effective crop farming?
Understanding salt tolerance for different plant species
What are coral species which form connected reefs greatly impacted by?
Changes in oceanic temperature
How do coral polyps receive nutrition?
From an algae that lives in the polyps endodermis
How do increasing ocean temperatures cause coral bleaching?
The algae that feeds them cannot survive in low temperatures so when it increases they leave the coral tissue?
What is the typical optimal growth range in temperate waters?
20 - 30 C
What can quadrats and transects measure?
The distribution of a plant or animal species in response to an incremental abiotic factor
What are quadrats?
Rectangular frames of known dimensions that can be used to establish population densities
What are transects?
A straight line along an abiotic gradient from which population data can be recorded to determine a pattern
What can using quadrats and transect lines simultaneously help generate?
Population data
What will quadrats show about population data?
The changing distribution pattern of a species in response to a change in an abiotic variable
What can using population data from quadrats and transect lines help identify?
Optimal conditions, zones of stress and zones of intolerance
What are transects used to assess?
Species distribution in correlation with any abiotic factor that varies across a measurable distance
What is a kite graph used to represent?
Changes in species distribution
What does the relative width of each kite represent?
The abundance of an organism at a particular point along a transect
What is an ecological niche?
The functional position and role of an organism within its environment
What components will an ecological niche have?
The habitat
Activity patterns of the organism
Resources it obtains from the environment
The interactions that occur with other species in the community
What does an ecological niche consist of?
All physical and biological conditions which determine the organisms survival and reproductive prospects
What happens if two distinct species share an identical niche?
There will be interspecific competition for available space and resources
What will interspecific competition result in?
The fitness of one being lowered by the presence of the other
Why will the less well adapted species be eliminated from the niche?
As it will struggle to survive and reproduce
What are the two responses of interspecific competition?
Competitive exclusion and resource partitioning
What is competitive exclusion?
One species uses the resources more efficiently driving the other species to local extinction
What is resource partitioning?
Both species alter their use of the habitat to divide resources between them
Why will some species not be able to occupy their entire niche?
Due to the presence or absence of other species
So what happens if a species cannot occupy the entire niche?
They may occupy a smaller subset of their niche than is theoretically possible
What is a fundamental niche?
Where an organism could live
What is the fundamental niche also known as?
The theoretical habitat
Why may a species not live in all of their fundamental niche?
Due to presence of competing species
What is a realised niche?
Where an organism does live
What is a realised niche also referred to as?
The actual habitat
What is a keystone species?
A species that has a disproportionately large impact on the environment relative to its abundance
What are the three types of keystone species?
Predators
Mutualism
Engineers
What are predators?
They exert pressure on lower trophic levels to prevent them from monopolising certain resources
What are mutualists?
They can support the life cycle of a variety of species within a community
What are engineers?
They can refashion the environment in a manner that promotes the survival of other species
What is an example of a predator?
Sea stars prey on urchins and mussels preventing mussel overpopulation and coral reef distruction
What is an example of a mutualist?
Honey bees pollinate a wide variety of plant species continuing the plant life cycle
What is an example of an engineer?
Beavers build dams that transform the environment in a manner that allows certain other species to survive
What are keystone species not?
The dominant species
What do keystone species not have to be?
Apex predators
How can the interactions between species in a community be classified?
According to their effect on the organisms involved?
What is herbivory?
The act of eating only plant matter
What may herbivores employ?
Different feeding strategies
What are the two ways herbivory may affect the plant species?
It may be harmful or beneficial
What is an example of herbivory being damaging to the plant species?
Beetle may feed too hard on the leaves causing crop failure
What is an example of herbivory being beneficial to the plant species?
Fruit-eating animals spread the seeds from fruit in their poo promoting seed dispersal
What is predation?
A biological interaction where predator hunts and feeds on prey
Why are predators and preys population levels inextricably intertwined?
Because the predator relies on the prey as their food source
What happens if prey population drops?
Predator numbers will dwindle as intraspecific competition increases
What happens if the prey population increases?
Predator population increases due to the over abundance of a food source
What is symbiosis?
The close and persistent interaction between two species
What are the two types of symbiotic relationships?
Obligative or faculative
What are the three types of symbiotic relationships?
Mutualism
Commensalism
Parasitism
What is mutualism?
An ongoing interaction between two species whereby both species benefit from the interaction
What is an example of mutualism?
Plover birds pick food from between the jaws of crocodiles cleaning their teeth in the process
What is commensalism?
An ongoing interaction between two species where on benefits and the other is unaffected
What is an example of commensalism?
Remora attach to the underside of larger predatory fish and feed off the uneaten food scraps
What is parasitism?
The ongoing interaction between two species whereby one species benefits at the others expense
What is an example of parasitism?
Ticks infest the skin and fur of host animals feeding off the host and potentially causing disease
What do reef building coral form a symbiotic relationship with?
Zooxanthellae
What is zooxanthellae?
Photosynthetic unicellular algae
What are coral?
Colonial organisms made up of individual polyps connected by a layer of living tissue
Where does zooxanthellae live?
Within the cells of the corals endodermis
What does the coral provide zooxanthellae?
A protective environment and source of inorganic compounds
How does coral provide the algae with a protective environment?
It secretes calcium carbonate to build a skeleton which encases the polyps
How does the coral provide the algae with a source of inorganic compounds?
The coral recycles the algaes waste product and supplies carbon dioxide
How does the algae help the coral?
Provides the coral with a source of nutrition ( oxygen, glucose and other organic molecules?
Excluding nutrition, how else does the algae help the coral?
It removes waste products
What gives the coral its bright colour?
The algae
What happens when there is a large scale loss of zooxanthellae from the coral?
Bleaching coral
How does bleaching affect the coral?
The coral begins to starve and will dies unless the algae comes back
What three conditions can cause coral bleaching?
Changes in light availability
Temperature increases
Ocean acidification
