Ecology! Flashcards
Define population ecology
The study of factors affecting the size of a population and how it changes over time.
What patterns for the stability of populations can emerge - name three
- Reaching a stable size and staying there 2. Fluctuating regularly 3. Rising and falling in regular cycles.
Define population
A group of individuals of a single species living in the same general area.
True or false: Populations cannot be defined by physical boundaries.
False - e.g. islands.
Name the two types of competition and describe them.
INTRAspecific competition - members of the SAME species competing. INTERspecific competition - members of DIFFERENT species competing.
Name the three important population concepts
1.Populations have structure 2. Populations are regulated 3. Populations are dynamic over time.
How do birth and death affect populations?
Births add members to a population and death removes them.
Describe Type 1 organisms in terms of their mortality patterns. Give an example.
They have their highest mortality rates in the older population. Tend to be species with a long life span who live in stable environments. E.g. primates.
Describe Type 2 organisms in terms of their mortality patterns.
They have a constant mortality rate throughout the stages of life. Tend to be species who live for a medium amount of time who live in relatively stable environments. E.g squirrels.
Describe Type 3 organisms in terms of their mortality patterns.
Have their highest mortality rates in juveniles. Tend to be species who live for short lengths of time in unpredictable environments. E.g many fish.
True or false: A species can only show one type of survivorship.
False - animals can show multiple types of survivorship throughout different life stages.
name three types of spatial organisations a species can show
Random, uniform and clumped.
When does random dispersion occur?
In the absence of strong competition or a constant distribution of key necessary factors.
Give two examples of uniform dispersion.
Planted crops, territorial animals.
When would clumped dispersion occur?
When there are certain areas of high resource availability, mating behaviours need to occur, the presence of strong predators.
When would you see exponential growth of a population?
When ideal conditions allow for all individuals to have an abundance of critical resources and reproduce at physiological capacity
Describe the Logistic Growth Model
The per capita rate of a population growth approaches zero (meaning the the population size is at capacity.
When would conservation biologists use the logistic growth model?
When predicting the rate of recovery for small populations and when estimating the critical size below which a population is at risk of extinction.
name two density dependent factors
Competition for resources, territoriality, disease, toxic waste etc
Name a density independent factor
Extreme weather conditions.
Define Ecosystem services
The processes by which natural ecosystems help sustain human life
Why is genetic diversity important?
Larger genetic diversity increases the fitness of offspring and therefore allows more to survive/ have the ability to reproduce.
True or false: Species richness does not alter by varying altitude.
False - Species at very low or high altitude are less abundant.
What are the four major threats to biodiversity?
Habitat loss, overharvesting, introduced species, and global change.
Define invasive species.
Animals, plants and other organisms which have been introduced to areas they are not normally found. They have negative effects on that new environment.
Define overharvesting
The harvesting of organisms at a rate which exceeds the ability of their population to reproduce.
Name three examples of global change which effect biodiversity
Climate change, Atmospheric temperature change, and major ecosystem changes.
What is a biodiversity hotspot?
A relatively small area with numerous endemic , threatened or endangered species.
Why do movement corridors help conserve biodiversity?
They allow for separated habitats to be re-joined, allowing for a larger range of species to interact.
Name three ways in which biodiversity can be conserved
Increase of protected areas, safeguarding of existing protecting areas and the conservation of habitats.
What does conservation biology integrate? Name three areas.
ecology, physiology, molecular biology, evolutionary biology, genetics.
Define ecology
The study of interactions between organisms and their environment.
Name the 6 levels of ecological organisation
- Biosphere 2. Biome 3. Ecosystem 4. Community 5. Population 6. Individual
True or false: Distribution of threatened species is not similar for different taxonomic groups
True
Offer a likely explanation for why there are more species closest to the equator.
Stability of habitat/seasons, greater abundance of food.
Name some factors which could suggest why global patterns in ecology vary.
Temperature, rainfall, area of habitat, size and closeness of islands to main lands, immigration and extinction rates.
Offer an explanation as to why we see a pattern of larger/longer mammals and birds further away from the equator
The animals at the equator need to lose heat and the animals further away need to conserve it e.g. foxes in cold climates have much larger coats than those living in tropics
What process do primary producers use to make energy?
Photosynthesis
What is the Gross Primary Production?
The total amount of energy generated by autotrophs in an ecosystem
What is the Net Primary Production?
Gross Primary Production - respiration by autotrophs
Name three limiters of Net Primary Production
Energy available, water availability, and nutrients available.
In food chains, name the four trophic levels
Primary producers, primary consumers, secondary consumers, tertiary consumers
Roughly what percentage of energy is retained at each level of a food chain?
A tenth
Why is the biomass pyramid used?
Because different levels of the food chain will have different biomasses depending on abundance, but still pattern of energy loss remains
What does it mean if an ecosystem is driven by its input?
That the increase in energy at all levels stems from the abundance of the autotrophs i.e. more grass means more zebras and lions.
What does it mean if an ecosystem is driven by “top-down” control
That herbivore numbers are limited by the presence of predators, not by the abundance of autotrophs
How can dominant species be described in relation to an ecosystem?
As the most common, biggest species present in an ecosystem.
What is special about keystone species
They may not be more numerous than other species within the ecosystem, but play a pivotal roll because of their niche.
What does it mean if a species is an “ecosystem engineer?”
They change the environment in someway which opens up the possibility for new niches i.e. beavers building a damn.
define bioaccumulation
Increasing concentrations of pollutants and other non-metabolised molecules up the food chain.
What causes competition between organisms?
Lack of resources
What is the competitive exclusion principle?
If two species compete for exactly the same resource, one will drive the other to local extinction
Define an organism’s ecological niche
The position of a species within the ecosystem
What can the “fundamental” niche of an organism be defined as?
The niche which could potentially be occupied by a species
What is the “realised” niche of an organism?
The niche the species is actually able to occupy
What is a main factor in stopping species from occupying their fundamental niches?
Competition e.g. the presence of another species in the same area limits availability for the first species
What does “sympatry” refer to in terms of interspecies relationships?
When they coexist
What does “allopatry” refer to in terms of interspecies relationships?
When two species live separatly
Define Character displacement
A tendency for characteristics to be more divergent in sympatric populations of two species than in allopatric populations
What does character displacement result in?
Reduced competition due to organisms differing more
Describe the “evolutionary arms race”
Predators develop a method of capturing prey, and as a result the prey develop a method of evasion. This cycle repeats and drives evolution.
What are the two types of mutualistic relationship and what do these mean?
Facultative = an optional mutualistic relationship. Obligate = At least one of the two species involved cannot survive without the other
