B1 - Species Interactions
1) Understand the difference between direct, indirect, and cascading effects of interactions and be able to tell examples.
direct effects: Impact of the presence(or change in abundance) of species A on species B in a two species interaction.
indirect effects: Impact of the presence(or change in abundance) of species A on species C via an intermediary species. (A—>B—>C)
cascading effects: Impacts extend across three or more trophic levels and can be top-down.(predator—> herbivore—>plant) or bottom-up(plant—>herbivore—>predator)
2) Understand the concept of keystone, foundation, and indicator species and be able to tell examples.
keystone species: Profoundly affect other species in the community. No or limited functional redundancy.
foundation species: Define and structure certain forest ecosystems. Typically physically modify the environment.
indicator species: Measure of environmental conditions.
3) Tell examples for each of the following types of positive or neutral interaction:
mutualism: [Mutualism, ++]
Ants and acacia trees
Ants and aphids
Yucca moths and yucca
fungus and photosynthetic species
commensalism: [Commensalism, +0]
Epiphytes on trees
Species A using an abandoned nest from Species B
E-coli in human gut.
facilitation: [Facilitation, 0+]
Plants associating with N-fixing organisms
Woodpeckers makes a cavity, purple martins move in
4) Give examples for each of these types of interactions that are positive for one species and
negative for the other:
competition: [+-], [-,-]
both partners negatively affected (not necessarily to the same degree) because attempt to use same scarce resource.
predation: [+-]
consumption of one species by another species that’s usually larger.
Mammals eating smaller animals, herbivory, eating fruit….
plants not killed, partial “predation”.
parasitism:[+-]one benefits, the other (which is usually larger) is harmed.
Includes pathogens, which are usually fungi, bacteria, and viruses.
inhibition:[+-]
one species inhibits (hurts) the growth of another
Allelopathy: chemical inhibition of one plant by another.
5) Understand mechanisms how species interacts, how species and plant communities respond to interactions and tell examples.
Mechanisms:
physical interactions: ex- ferns and lichens on trunks and branches, damage when tree falls.
biochemical interactions: ex- change in water, nutrient availability
Responses:
Resource substitution: ex- change diet, N fixation
Spacial separation: ex- tree spacing, root depth.
Temporal differentiation: ex- ephemeral understory
Changes in single plants: phenology, plant shape. ex - sun leaves instead of shade leaves, height/diameter ratio.
Changes in plant communities: ex- different species after a disturbance, patchiness that reflect soil moisture, or nutrient patterns.
B1 - Species Interactions
1) Understand the difference between direct, indirect, and cascading effects of interactions and be able to tell examples.
direct effects: Impact of the presence(or change in abundance) of species A on species B in a two species interaction.
indirect effects: Impact of the presence(or change in abundance) of species A on species C via an intermediary species. (A—>B—>C)
cascading effects: Impacts extend across three or more trophic levels and can be top-down.(predator—> herbivore—>plant) or bottom-up(plant—>herbivore—>predator)
2) Understand the concept of keystone, foundation, and indicator species and be able to tell examples.
keystone species: Profoundly affect other species in the community. No or limited functional redundancy.
foundation species: Define and structure certain forest ecosystems. Typically physically modify the environment.
indicator species: Measure of environmental conditions.
3) Tell examples for each of the following types of positive or neutral interaction:
mutualism: [Mutualism, ++]
Ants and acacia trees
Ants and aphids
Yucca moths and yucca
fungus and photosynthetic species
commensalism: [Commensalism, +0]
Epiphytes on trees
Species A using an abandoned nest from Species B
E-coli in human gut.
facilitation: [Facilitation, 0+]
Plants associating with N-fixing organisms
Woodpeckers makes a cavity, purple martins move in
4) Give examples for each of these types of interactions that are positive for one species and
negative for the other:
competition: [+-], [-,-]
both partners negatively affected (not necessarily to the same degree) because attempt to use same scarce resource.
predation: [+-]
consumption of one species by another species that’s usually larger.
Mammals eating smaller animals, herbivory, eating fruit….
plants not killed, partial “predation”.
parasitism:[+-]one benefits, the other (which is usually larger) is harmed.
Includes pathogens, which are usually fungi, bacteria, and viruses.
inhibition:[+-]
one species inhibits (hurts) the growth of another
Allelopathy: chemical inhibition of one plant by another.
5) Understand mechanisms how species interacts, how species and plant communities respond to interactions and tell examples.
Mechanisms:
physical interactions: ex- ferns and lichens on trunks and branches, damage when tree falls.
biochemical interactions: ex- change in water, nutrient availability
Responses:
Resource substitution: ex- change diet, N fixation
Spacial separation: ex- tree spacing, root depth.
Temporal differentiation: ex- ephemeral understory
Changes in single plants: phenology, plant shape. ex - sun leaves instead of shade leaves, height/diameter ratio.
Changes in plant communities: ex- different species after a disturbance, patchiness that reflect soil moisture, or nutrient patterns.
