Chapter 37-38 - Community and Ecosystem Ecology Flashcards
What is a biological community?
All of the populations of organisms living close enough for potential interaction. Described by their species composition/biodiversity.
What do community ecologists study?
How abiotic factors and interactions between populations affect the composition and distribution of communities.
Biodiversity depends on __________ ___________ and ______________ ________________ .
Species richness and relative abundance.
What is species richness? What is relative abundance?
Species richness: the number of different species.
Relative abundance: the proportional representation of a species in a community.
What are the benefits of greater species richness and more even the relative abundance?
Communities with these characteristics are more stable, healthy, and able to respond/adapt to change better.
Does modern agriculture have high or low biodiversity? What are some side effects of this?
Low biodiversity making plants susceptible to pathogens and insects which leads to increased use of chemicals.
What are interspecific interactions? What are 3 types that we looked at?
Relationships between individuals of different species. May be helpful or harmful. i.e. competition, predation and herbivory.
What is an ecological niche?
The sum of a species use of the biotic and abiotic resources in its environment (its “role” or “occupation”).
What is interspecific competition? Is it helpful or harmful to the individuals involved?
Where 2 species ecological niches overlap and they compete for the same resources. Both species are negatively affected (harmed).
What is competitive exclusion?
When one species outcompetes and eliminates the competitor from its niche. i.e. arctic and red fox.
What is intraspecific competition?
Competition for resources between individuals of the same species.
What is predation? Is it helpful or harmful to the individuals involved?
When one species (predator) kills and eats another species (prey). Helpful to predators, harmful to prey.
What is herbivory? Is it helpful or harmful to the individuals involved?
The consumption of plant parts or algae by animals. Helpful to animals, harmful to plants.
How can predation and herbivory lead to changes in the species involved?
It leads to adaptations!
i.e. camouflage, mechanical/physical defences or chemical defences which predators/animals then adapt to.
What is co-evolution?
A series of reciprocal evolutionary adaptations in 2 species. A change in one species acts as a new selective force on another species.
What are 5 levels of the trophic structure and their role?
Primary producers (autotrophs)
Primary consumers (herbivores)
Secondary consumers (eat primary consumers)
Tertiary consumers (eat secondary consumers)
Quaternary consumers (often the highest level)
What are scavengers, detritivores, and decomposers and why are they important?
Scavengers – large animals that feed on carcasses/carrion.
Detritivores – eat decaying organic material.
Decomposers – secrete enzymes to digest dead organic material.
They breakdown molecules and provide raw materials for producers.
What is a food web?
A network of interconnecting food chains that more realistically show how species are connected (compared to food chains).
What is a keystone species and some examples?
A species whose impact on its community is much larger than its biomass or abundance would indicate. Occupies a niche that holds the rest of its community in place.
i.e. wolves, beavers, otters in kelp communities.
What is a trophic cascade?
When removal of a predator has effects at more than one trophic level (because predators are often keystone species).
What is symbiosis?
The long-term association of two different species within a community. Can be helpful or harmful to the species involved.
What are 3 types of symbiosis and are they helpful or harmful to the species involved?
Mutualism (helpful to both).
Parasitism (helpful to one, harmful to the other).
Commensalism (helpful to one, neutral to the other).
What are some common disturbances to communities?
Fires, storms, floods, droughts, development, deforestation, agriculture, etc. Can be natural and human influenced.
What is ecological succession?
The replacement of species within a given area over time.
