Flashcards in LEC 22 Deck (57):
all of the different popula&ons of organisms (including bacteria) that live within a designated area
Community ecology focuses on:
–factors around community assembly –autecology* of specific residents in the context of the community – interac&ons among the organisms
The study of an individual organism or a single species
Species respond ______ to environmental gradients, not as a group: Species respond so composition of communities along a continuum will vary: one species may be present in several communities, some only in one.
a region of transition between two biological communities.
Places between abrupt environmental changes
then also change abruptly, not gradually, though there are some species
The totality of ways a species uses resources or responds to condi&ons of its environment: food consumed, space used, temperature and moisture requirements, etc.
can be visualized as an n-‐dimensional hyperspace defined by n axes (axes would include all physiological, morphological, behavioral, environmental, etc. condi&ons relevant to the niche)
Axes that define niche space may involve physiological, morphological, behavioral, environmental and other types of traits/conditions
The intersection of niche spaces occupied by tropical and temperate tree species as defined by
and specific leaf area (SLA)
One of many factors that canmodify niche space.
•Niches are restricted because other species share the same limited resource(s)
types of interspecific competition
In _____, organisms use up resources directly. Once used, the resource is no longer available for other species to use.
In ____, one organism prevents other organisms from using the resource.
Of the two mechanisms, exploitation competition is the more common
refer to the environmental position that species occupy in an ecosystem
fundamental and realized niche
represent all the environmental conditions where a species is able to live
is where the species actually lives
Species with the exact same niche cannot co-exist indefinitely when resources are limiting. One species will eventually drive the other to extinction.
Gause’s Law of Competitive Exclusion:
Some possible environmental niche axes for plants:
–Soil moisture and root depth
–Soil nutrient par&&oning, maybe through microbial symbionts
theory is a framework to understand how competitor traits can maintain species diversity and stave-off competitive exclusion even among similar species living in ecologically similar environments.
Growth patterns of plant competion
–Grow taller, wider, denser (light and space)
in time or space, may allow co-existence.
partitioning of resources
When species divide a niche to avoid competition
partitioning of resources
How plants compete (or not) with each other : PLant competition
a. Growth patterns
b. Sequestration of critical resources
c. Liebig's Law of the Minimum
d. Retreat from competition
Sequestration of critical resources
–Accumulate, sequester cri&cal resources and deny competitors their use •Brachypodiumbinpinnatum and phosphorous •Opposite strategy: CA na&ves and nitrogen
It states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor)
leibig's law of minimum
–Develop tolerance for harsh condi&ons
retreat from competition
determine annual grassland species composi&on in a given year
Niches defined, in part, by ____ and _____
seed dynamics and species phenology
Facilitated by combination of shorter- and longer-lived annual seed banks in combination withvarying weather conditions in different years that favor different species
facilitated by different species being favored in different years
____ each respond differently to timing, pattern of rainy season
Grasses, forbs, and clovers
germina&on and flowering of some species occur late in season
Other factors of species coexistance in california annual grasslands Other factors:
slope/aspect, soils, livestock and fire disturbance, gopher/ground squirrel activity
predator and prey
Herbivory responses by plants:
(secondary metabolites), makes plants toxic or taste bad
prickles, thorns, spines, sclereids, barbed hairs, gummy saps
fold up parts so they are less vulnerable
structures that deter aWack, such as fake eggs and mimicking of rocks
mimicry or camouflage
–Mustard family (Brassicaceae) and cabbage buWerflies – larvae blend in with mustard leaves AND are able to digest mustard oils
–Monarch buWerflies and milkweed (Ascepiadaceae) family: consuming cardiac glycosides of milkweeds make them undesirable prey
Coevolutionary responses by herbivores
2 or more organisms interact in more or less permanent rela&onships due to coevolu,on
mutually responsive adapta&on between two species. Myriad examples in pollinators or parasites.
Interac,ons between species influence and CHANGE the gene pools and traits of BOTH species.
n fixing bacteria
Mutualism: mycorrhizal rela&onships
“mushrooms” and “toadstools” are the frui&ng body of mycorrhizal fungi
a partnership between a fungus and an alga. (Mutualism
dodder on pickleweed
External plant parasite
world’s biggest flower? Because it is a parasite on a large vine.
n association between two organisms in which one benefits and the other derives neither benefit nor harm.
help sometimes benign
s the process of change in the species structure of an ecological community over time, nothing remains the same habitats are constantly changing
s the series of community changes which occur on an entirely new habitat which has never been colonized before. For example, a newly quarried rock face or sand dunes.