Ch. 54 Flashcards
What is a biological community?
biological community:
the assembly of various specie populations living close enough for potential interaction
Give an example of a biological community.
the animals and plants that surround a water hole in South Africa are part a savanna community
What are interspecific interactions?
relationships between species in a community;
they affect species survival and reproduction
Give some examples of interspecific interactions.
competition, predation, herbivory, symbiosis (parasitism, mutualism, and commensalism), and disease
What is the competitive exclusion principal?
that two species competing for the same limiting resources cannot coexist in the same place
What is interspecific competition?
when species compete for a resource in short supply; it can be detrimental to both species (–/–)
What is competitive exclusion?
the local elimination of competing species;
can occur as a result of strong competition
What is an ecological niche? (aka how does the specie survive?)
The total of a species’ use of biotic and abiotic sources
What is a fundamental niche?
A place where a species COULD survive
What is a realized niche?
A place where a species actually survives/resides
Are fundamental and realized niche always the same?
No, because of competition
Can similar species coexist in a community?
Yes, if there are one or more significant differences in their niches and with the help of resource partitioning
What is resource partitioning?
The differentiation of ecological niches; it enables similar species to coexist in a community
Predation
The interaction where one species, the predator, kills and eats the other species, the prey
What adaptations do prey species develop?
Defensive adaptions, or behavioral defenses; includes hiding, fleeing, self-defense, and alarm calls
What adaptations do predator species develop?
Feeding adaptations; includes claws, teeth, fangs, stingers, and poison
What are the four types of adaptations?
Defensive (prey), feeding (predator), morphological (structural), physiological defense (cells or tissues)
What trait do animals with effective chemical defense exhibit?
Aposematic coloration - bright warning coloration; makes predators cautious of them as preys
Herbivory
An interaction in which an herbivore eats part of a plant or alga; caused evolution of plant mechanical and chemical defenses, and the resulting adaptations by herbivores
Parasitism
Where one organism, the parasite, derives nourishment from another organism, the host, which is harmed in the process
Pathogens
Disease-causing agents that are typically bacteria, viruses, or protists
Mutualism (mutualistic symbiosis)
An interspecific interaction that benefits both species
Commensalism
Where one species benefits and the other is unaffected; not as common in nature
What is coevolution?
Evolutionary adaptations done in response to two interacting species; little evidence for this in most interspecific interactions
Name two fundamental features of a community structure.
Species diversity and feeding relationships
Species diversity
the variety of organisms that make up the community; has two parts - species richness and relative abundance
Species richness
the total number of different species in the community
Relative abundance
the proportion each species represents of the total individuals in the community
What is a monoculture
a community with no species diversity
True or False: if two species have the same species richness, they must have the same relative abundance
False, they can have different relative abundance
Trophic Structure
the feeding relationships between organisms in a community; a key factor in community dynamics; link by food chains from producers to top carnivores
What are the five levels of a general food chain? (smallest to largest)
Primary producers (plant)
primary consumers (herbivore)
secondary consumers (carnivore)
tertiary consumers (carnivore)
quaternary consumers (carnivore)
Food webs
a branching good chain with complex trophic (feeding) interactions
What is the arrow rule?
the arrows go the way the energy flows
Difference between a food chain and a food web?
Food web is the entirety of the energy transfers (through consuming) in a community, but a food chain is usually only a few links of a food web long
What is the energetic hypothesis?
says that length is limited by inefficient energy transfer
What is the dynamic stability hypothesis?
says that long food chains are less stable than short ones
Is there more data that supports the energetic hypothesis or the dynamic stability hypothesis?
the energetic hypothesis
Dominant species
those that are most abundant or have the highest biomass; they exert powerful control over the occurrence and distribution of other species; said to be most competitive in exploiting species and most successful at avoiding predators
Compare and contrast keystone and dominant species
Similarities: both exert strong control on a community
Differences: keystone species are not necessarily abundant in a community like dominant species are
_____ influences species diversity and composition.
disturbance
what is the nonequilibrium model
describes communities as constantly changing after being disrupted by disturbances
What is disturbance?
an event that changes a community, removes organisms from it, and alters resource availability; can often times be necessary
ex: fire
Intermediate disturbance hypothesis
suggests that moderate levels of disturbance can foster higher diversity than low levels of disturbance
Ecological succession
the sequence of community and ecosystem changes after a disturbance
Where does primary succession occur
where no soil exists when succession begins
Where does secondary succession occur
in an area where soil remains after a disturbance
Pioneer species
species that are early arrivals to the ecosystem and have remained there for long periods of time
Name three ways that pioneer species can affect later-arriving species
- can facilitate appearance of later species by making the environment favorable
- can inhibit establishment of later species
- can tolerate later species but have no impact on them
Areas with periodic fires are most likely to have what kind of succession?
secondary
Areas affected by a volcanic eruption are most likely to be have what kind of succession?
primary
Name 2 key factors correlated with a community’s species diversity
geographic location and size
