Unit 3 Flashcards
Why does species distribution occur?
The distribution of any given species is
the result of evolutionary forces having
shaped its ecological interactions.
What are the two factors that species can interact with?
Abiotic factors (non-living), Biotic factors (Other living things)
What is population distribution?
Where the animals are found
What is population abundance?
How dense a population is
What is demography?
Age structure of the population
What is the definition of a population?
It is a group of individuals of a
single species living in the same
general area at the same time.
These individuals rely on the same
resources, are influenced by similar
environmental factors, and are likely
to interact and breed with one
another.
What is the range of a population?
The range of a species is the area where it is found during its lifetime
and includes areas where individuals may migrate or hibernate.
What determines the range of a said species?
abiotic factors and positive and negative interactions with biotic
factors define the range of a species.
What are some examples of positive and negative biotic factors?
Predators, parasites, disease, and competitors act as negative interactors, while prey and food sources act positive interactors.
What are some examples of abiotic factors?
Temperature, water availability, salinity,
sunlight, soil.
How do we calculate population density?
Density is the number of individuals
within a population per unit area or
volume.
How to we define dispersion in a population?
Dispersion is the pattern of spacing
among individuals within the
boundaries of the population.
What are metapopulations?
Metapopulations consist of a group of spatially separated populations of the same species which interact at some level.
Are ecosystems homogenous in space and time? Are they completely appropriate to all species? What does this cause?
No they are not. This causes fluctuation in densities and influences migration patterns.
What three distributions we often see in populations?
A clumped distribution, a uniform distribution and a random distribution.
What is a condition necessary for populations to uphold if subpopulation are part of a metapopulation.
There must be gene flow between subpopulations.
What can reduced gene flow cause?
Allopatric speciation or sympatric speciation.
What is a life table?
A life table includes age-specific data
of the survival and reproductive
patterns of a population.
What is a survivorship curve?
A survivorship curve displays the proportion or numbers in a cohort still
alive at each age
How is change in population size calculated?
Birth+immigrants-(death and emigrants)
When this number is positive, the population is growing
When ressources are unlimited, what theoretically happens to growth?
Unlimited growth occurs
Why does unlimited growth never occur for a long period of time?
Resource availability or access
decreases as a population grows, which makes it harder for a population to grow.
How is growth rate calculated?
Difference in population over difference in time.
What function does population growth look like when the population appears in a new environment or numbers have been greatly reduced?
Exponential curve
What factors appear to influence a population as its density grows?
Density dependant factors
What is intraspecific competition?
It is a type of interaction where individuals in a population compete for limited resources. (if variation exists within the population, the better competitors will outcompete the others and lead to the death of the poorer competitors.)
What is the influence of increased population density on immigration?
It causes reduced immigration, as there are less ressources available for new individuals.
What is threshold host density?
Threshold host density refers to the minimum concentration of individuals necessary to sustain a given disease.
Why does increased density mean for easier spread of disease.
Disease spread easier when individuals are close to each other. Therefore, in a dense population, disease will spread easier as the Individuals are closer to each other.
What is carrying capacity?
It is defined as the maximum
population size that a particular
environment can sustain. (number at which the population stops growing because of density dependant factors.
What are some examples of limiting ressources?
Energy, shelter/refuge, nutrients,
water, and nesting sites.
What is the logistical growth model?
It is a mathematical model that incorporates
the change in growth rate as the
population size nears the carrying
capacity
What happens to the growth of a population as the population increases?
It goes down
What is a community?
A community is an association of populations of different species that live and interact in the same place at the same time.
What is a metacommunity?
A metacommunity is defined as a set of local communities that are linked by dispersal.
What is interspecific competition? Is it a win win interaction, a lose win or a lose lose interaction?
It is species competing for a specific resource. It occurs when different species compete for a particular resource that is in short supply. It is lose lose.
What are some consequences of interspecific competition?
Interspecific competition can lead to lead to competitive exclusion; the local
elimination (extirpation) of one of the two competing species if it is too strong. It can also cause the organism’s niche to change over time.
What is the competitive exclusion principle (Gause’s law)?
It states that two species cannot coexist in a community if their niches are identical.
What is an ecological niche?
An ecological niche is the total of an organism’s use of the biotic and
abiotic resources in its environment. (what they need to survive)
What is a fundamental niche?
A fundamental niche is the range of conditions that allows a species to
survive and reproduce. (occurs in the absence of competition) (So it is the theoretical span where a species can thrive)
What is a realized niche?
A realized niche is the range of conditions under which a species actually occurs in natural communities. (Real span over which a species can thrive)
What is ressource partitioning?
It is the differentiation of niches, via
natural selection, that enables similar
species to coexist in a community.
How can competition influence evolution?
It can cause animals that share the same niche to evolve towards a different niche than competitors to be better suited for the environment.
What usually causes more character change: allopatric conditions or sympatric conditions?
Sympatric conditions (in allopatric conditions, competition is absent, so character displacement isn’t necessary)
What is predation? What is a consequence of this interaction?
Refers to a carnivorous interaction
where one species, the predator, kills
and eats the other, the prey.
Predator-prey interactions help shape evolution via natural selection.
What are the adaptations predation brings about?
Feeding adaptations of predators
(include claws, teeth, fangs, stingers, and poison)
Defensive adaptations of prey (include hiding, running, camouflage, and
poison.)
What are some predator strategies?
Chasing prey, camouflage or mimicry to
avoid notice by their prey, and
structures that attract prey.
What are some prey strategies?
Prey strategies against predation
include fleeing, hiding, living in groups, mechanical defences, special coloration, mimicry.
What is mimicry?
It is the close external resemblance of an animal or plant (or part of one) to another animal, plant, or inanimate object. (Serves to mislead other organisms).
What are the two types of colouration and what purpose do they serve?
- Aposematic coloration. It provides a
warning to predators, who will
tend to avoid prey with bright
coloration because it signifies
chemical defences. - Cryptic coloration. It provides
camouflage, making a prey
harder to see.
What is batesian mimicry?
batesian mimicry occurs as a palatable or harmless species evolves to
mimic an unpalatable or harmful species.