Ecological Communities Flashcards
what holds communities together and determines their nature and stability
species interactions
Exploitative interactions
Interactions where one member exploits another for its own gain
examples of exploitative interactions
- predation
- paraistism
- herbivory
7 main categories of species interactions
- competition
- predation
- paratisim
- communalism
- Mutualism
- Herbivory
- Amensalism
competition
occurs when resources are limited
describe the effect of competition on two species
each species has a NEGATIVE effect on the OTHER species as each takes resources away from the other
describe the effect of PREDATIOn on two species
negative effect on one species while a positive effect on the other
describe the effect of parasitism on two species
negative effect on one species and positive on the other
describe the effect of herbivory on two species
negative effect on one species and positive on the other
describe the effect of mutualism on two species
both species benefit from the interaction
describe the effect of commensalism on two species
One species benefits while the other is not affected
Amensalism
Variation of competitive relationship where one organisms in harmed and the other is unaffected (not benefiting)
intraspecific competition vs interspecific competition
intraspecific:
Competition between members of the same species
interspecific:
Competition between members of different species
which type of competition can lead to competition exclusion
interspecific competition
competition exclusion
If one species is a better competitor than the other, they might exclude another species from using the resource entirely
how does competition create species coexistence
○ When neither competing species fully excludes the other and they can live side by side at a certain ratio of population size
○ Species adjust to their competitors to minimize competition between them
fundamental vs realized niche
fundamental:
the full niche of the species
realized:
Individual that plays only part of its role because of competition or other species interactions
Resource partitioning
The species in an area divide or partition the resources they use in common by specializing in different ways
what can lead to character displacement in species
resource partitioning
character displacement
○ Competition species evolve physical characteristics that reflect their reliance on the portion of the resource they use
○ Becoming more different = reduced competition
Predation
Process where individuals of one species (predators) hunt and consume other species (prey)
what species interaction structure food webs and influence community composition
predation
Evolutionary ramifications of predation
○ Predators that are more adept in capturing prey will likely live longer, healthier lives and provide better for offspring
○ Evolutionary adaptions that lead predators to be better hunters
*Prey face selective pressures to avoid predators
Parasitism
Relationship where one organisms (the parasite) depends on another (the host) for nourishment, support… While harming the host organism
Parasitoids
Insect parasites on other insects which kills them in the process
which species interaction results in coevolution
parasitism
coevolution
Host and parasite repeatedly evolve new responses to the other’s latest advancement
Herbivory
Occurs when animals feed on the tissues of plants
how does herbivory affect plants
Often does not kill a plant outright but instead affect its growth and reproduction
Mutualism
Relationship where two or more species benefit from interacting with each other
example of mutualism
symbiosis (Mutualism occurring between organisms that live physically close together)
Commensalism
Interaction where one species benefits and the other is unaffected
Community
Group of populations of organisms that live in the same area at the same time
Ecological communities relates to
Which species coexist
how they relate to one another
how communities change through time
trophic Levels
Rank in the feeding hierarchy of a food chain where organisms at a higher level consume those found at a lower level
where does the energy that drives interactions like predation ultimately come from
the sun via photosynthesis
first trophic level
producers/autotrophs
second trophic level
primary consumers (Consumers that eat producers; herbivores)
third trophic level
secondary consumers (Consumers that prey on primary consumers)
higher trophic levels (above third)
Tertiary consumers (Predators that eat secondary consumers which eat primary consumers like owls)
Detritivores vs decomposers
Detritivores ; Scavenge the waste products or the dead bodies of other community members
decomposers ; Break down leaf litter and other nonliving matter further into simpler constituents that can be taken up and used by plants
what are detritivores and decomposers known as
saprotrophs
where is most of the energy consumed in trophic levels
First trophic level with the producers contain a large amount of energy
______ amounts of energy is transferred to higher trophic levels
small
which trophic level contains the least amount of energy
tertiary level
why is the trophic levels shown in a Trophic pyramid diagram
Pyramid shape because biomass, energy and number of individuals decrease upward through the trophic levels
food webs vs food chains
food web:
a visual map of feeding relationships and energy flow that shows the many paths energy passes among organisms as they consume each other
food chain ;
a linear series of feeding relationships
which focuses on the movement of energy and distribution of biomass in the system
Keystone species
Species that has a particular strong or far-reaching impact where their removal from an ecosystem will alter a large portion of the food web
Trophic cascade
Where the disappearance of a top predator leads to dramatic changes at lower trophic levels
resistance vs resilience
resistance ;
When a community resists change and remain stable despite major disturbances
resilience ;
The community does change in response to the disturbance but returns to it’s original state quickly
Succession
A disturbance is sever enough to eliminate all or most of the species in a community that results in a series of changes in the composition and structure of a community
importance of pioneer species
Species that arrive first at a primary succession site and colonize the new ground
best pioneer species
lichen (part fungi and part algae)
Climax community
A community that remains in place with little modification until some disturbance restarts succession
two types of succession
primary succession and secondary succession
primary succession vs secondary succession
primary succession ;
Follows a disturbance that no vegetation or soil life remains from the community meaning It starts with a clean slate and the biotic community is built from scratch
(like with volcanic deposits)
secondary succession ;
A disturbance dramatically alters an existing community but does not destroy all living things or organic matter in the soil (like a fire or flood)
Invasive species
A species that spread widely and rapidly becomes dominant in a community and interferes with the community’s normal functioning after being introduced to an ecosystem - it is not native
when do invasive species become pests
Invasive species where their negative impacts outweigh the benefits
Two main characteristics of invasive species
- ability to spread rapidly and unimpeded in the new environment
- The negative impact on the native species, communities and ecosystems
What role does Natural selection play in predation
has led to adaptions in both prey and predator populations (venom, camouflage, mimicry, chemical detection…)
