Ch 41: Ecology Flashcards
Community
is an assemblage of species living close enough for potential interaction.
General things about interspecific
- Interspecific interactions can be positive of one species (+), negative (-), or neutral (0)
- Interspecific interactions include competition(only occurs when scarce resources), predation, and symbioses
- Interspecific (different species) Intraspecific ( same species)
- Interspecific competition can result in the elimination of one of the species. (a reproductive advantage in one species)
Interspecific competition
occurs when resources are in short supply, It is a -/- interaction between species involved
Competitive exclusion principle
When two species are vying for a resource, eventually the one with the slight reproductive advantage will eliminate the other. (resource partitioning)
An Ecological Niche
sum total of biotic and abiotic resources in its environment.
2 types of ecological niches
Fundamental niche and Realized niche
Fundamental niche
what a species potentially occupies
Realized niche
the portion of the fundamental niche the species actually occupies (because of comp)
How does competition occur?
When niches overlap competition occur
Predator prey interaction - or + or 0
prey interactions are +/- between two species
Cryptic coloration
camouflaged by coloring
Aposematic coloration
the poisonous animal is brightly colored as a warning
Batesian mimicry
nonpoisonous look like poisonous
Mullerian mimicry
Bad tastingresemble each other, predators avoid equally
Herbivory, - + 0
is also a +/- interaction, Herbivores eat only part of a plant or alga
Plant protective devices are
chemical toxins, spines, and thorns
Symbiosis
occurs when two or more species live in direct contact with one another
Parasitism
+/- interaction, the parasite derives its nourishment from the host. This decreases the survival, reproduction, and density of the host population
Mutualism
+/+ interaction, both species benefit,
Commensalism
+/0 interaction, one benefits the other is neither harmed nor benefits,
Species diversity
a measure of the number of different species in a community (species richness) and the relative abundance of each species
Trophic Structure
feeding relationships among organisms
Trophic levels
links in the trophic structure of a community
Flow of Energy is ?
Energy is transferred from the sun to plants to herbivores to carnivores and finally to decomposers.
Dominant Species
in a community the species with the highest biomass (all members of pop) or most abundant
Keystone Species
exert control on the community because of its important niche (a role it plays)
Ecosystem engineers
cause physical changes in the environment that affect community structure
The bottom-up model of community organization
proposes a unidirectional influence from lower to higher trophic levels
top-down model
proposes that control comes from the trophic level above
Biomanipulation
can help restore polluted communities
Disturbance and Diversity
Storm, fire, flood, drought, or human activity can be a disturbance and change a community by removing organisms or changing resource availability.
Intermediate disturbance hypothesis
moderate levels of disturbance create conditions that foster greater species diversity than low or high levels of disturbance
Ecological Succession
the transition in species composition
Primary Succession
Plants and Animals gradually invade region that was Lifeless (pioneer species)
Secondary Succession
The existing community has been cleared by a disturbance that leaves the soil intact (ex. Fire)
Stages of succession
- Early-arriving species and later-arriving species may be linked in one of three processes
- Early arrivals may facilitate the appearance of later species by making the environment favorable
- They may inhibit the establishment of later species
- They may tolerate later species but have no impact on their establishment
Two most important biogeographic factors
Latitude of the community and Area of the community
Latitude of the community
plants and animals are generally more abundant and diverse in the tropics and become less diverse as you move toward the poles
Area of the community
the larger the geographic area of a community the more species it has (if all other factors are held equal
Island biogeography
the study of “islands” is primarily by two factors
Rates of immigration and extinctions are influenced primarily by the ___and___ of the island from the mainland (source)
size and distance
Greater sizes of the island
higher the immigration rates and lower the extinction rates.
As the distance from the mainland increase,
the rate of immigration falls, extinction rate increases.
