What are the 6 types of direct two-species intractions?
- Interspecific competition
- Commensalism
- Mutualism
- Predation
- Herbivory
- Parasitism
What is an habitat?
The kind of place that a species lives in
Whay is a community?
All the species in a particular habitat
How are community structure determined by? What are some factors that can affect them?
Species richness (how many species) and species evenness (relative abundance of each species).
Abiotic factors: climate (hot/cold) , sunlight intensity…
Biotic factors: direct or indirect species interactions.
How are different species in symbiosis with eachothers?
When 2 species interact closely together over long term and at least one benefits.
When does coevolution happen? And what does it do?
When 2 species interacts closely over the long term.
Evolutionary changes in one species directly affect the evolutionnary changes that occur in the other.
(one specie is depent on the presence of the other -> if one disappear, the other also will)
What is an ecological niche of a specie?
It is all the ressources that it needs to survive, in a specific area. (ex: where it lives, what it eats, how it moves, …)
What is interspecific competition?
Competition is when individuals compete for one or more limited ressources.
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- Alleles allowing an organism to be better at getting ressources from their environment are selected for.
The more overlap there is in the ecological niche of two species, the mo
How can competition becomes intense?
When a ressource becomes so limited that a population is in danger of going extinct locally.
What is competitive exclusion?
When the two species can’t share the same limited ressource indefinitly, the species that is the least able to get the ressources may go extinct locally.
What is it called when natural selection selects traits that allows an organism to use a limited ressources differently, and the two species can now coexist.
Resource partitioning
What does resource partitioning requires? And what is it?
Character displacement.
When the range of phenotypes for a trait changes to reduce competition.
What is commensalism?
When one species gains an advantaga because of the existence of a second species. The second species is not affected.
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What is mutualism? And how can it be?
When both species benefit from thei interaction.
+ / +
-> Alleles that allow individuals to obtain a ressource from the other species at minimal cost are selected for.
Obligate (when the two species have evolved so close together that they become dependend of eachothers) or facultative.
What is predation? What is herbivory?
Predation is when one species kills and consume another species.
Herbivory is specifically when an anmal eats a plant.
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-> Alleles allowing prey or plants to avoid being eaten are selected for. (leads to defensive adaptations such as mimicry, camouflage, …)
-> Alleles allowing predators to capture preay or herbivore to cinsume plants are selected for. (leads to special predator adaptations such as camouflage, adaptative tooth shapes, …)
Often results in coevolution
What is parasitism?
When one species benefits at the expense of a second species, without immediately killing it.
+ / -
The second species is knows as the host species.
Although parasites often don’t kill the host, they can still lower the size of the host population. (weaken the host by taking its nutrients)
-> Alleles allowing the parasite to avoid detection and cause the least harm to the host are selected for.
-> Alleles allowing the host to reduce the effects of the parasite are selected for.
What can the number and type of species be affected by?
Biological or physical disturbance.
What is the intermediate disturbance hypotheisis?
It states that the greatest biodiversity will result from disturbances that:
1. Happen moderatly frequantly
2. Are moderatly intense
-> Com. with + biod. will be + resilient to collapse from env. changes.
What happens if disturbances are too infrequent or too light?
The species that are the best adapted to the unchanging environment will drive most other species to local extinction.
-> Biodiversity will be low (only the best adapted species)
Dominant species will monopolize the space and eliminate weaker species
What happens if disturbances happen too often or are too intense?
Only some species will be able to survive and reproduce
-> Biodiversity will be low (only the species with just the right ecological niches)
Eliminates many species and only surviving one reproduces.
