Competition Flashcards
Define competition.
An interaction brought about by a shared requirement for a resource in limited supply.
Define a resource.
Something that may be used up or consumed. Can be renewable or unrenewable.
Define scramble/exploitative competition.
Indirect competition. Approximately equal resource division.
Define interference/contest competition.
Direct competition. Resource division can vary greatly.
Define apparent competition.
Competition between 2 organisms not mediated by a resource. For example a shared parasite/predator.
How do scramble competition and interference competition impact population dynamics?
Scramble competition causes boom-bust dynamics. Interference competition causes population stability.
What are some proximate effects of competition?
Lost food/mates/territory.
What are some ultimate effects of competition?
Reduced fecundity and survivorship.
Does intraspecific or interspecific competition result in extinction of a species?
Interspecific competition.
What are the 3 options for competing?
Move/Migrate, adapt or die (not recommended.
Define self-thinning.
Progressive decline in density but an increase in biomass of the remaining individuals.
What do plants compete for above ground?
Light, CO2, favourable temperatures and pollinators.
What do plants compete for below ground?
Minerals, nutrients and water.
What wavelength of light is used in photosynthesis?
400-700nm - Photosynthetically Active Radiation (PAR).
What % of PAR is reflected?
10%
What % of PAR is absorbed by the canopy?
79%
What % of PAR is absorbed by the middle layer?
7%
What % of PAR is absorbed by low vegetation?
2%
What % of PAR reaches the forest floor?
2%
What is the function of phytochromes?
They detect the ratio of red to far-red light and signal this to the plant.
What are the 2 responses to shading?
Shade avoidance and shade tolerance.
What are the signs of Shade Avoidance Syndrome (SAS)?
Delayed germination. Stem elongation. Petiole elongation. Narrow leaves. Early flowering.
What are the signs of shade tolerance?
Increasing leaf area.
Orientating leaves to intercept light.
Reducing leaf overlap.
High chlorophyll b content.
Does above or below ground competition impact plants more?
Below ground competition.
What is kin recognition in plants?
Roots of kin plants are less likely to be influenced by a neighbouring plant.
Define antibiosis.
An interaction where 1 participant is unaffected or benefits whilst the other is harmed by a toxin released by the first.
Define ammensalism.
An interaction where 1 participant is harmed and the other is unaffected.
Define allelopathy.
Direct or indirect inhibition by a plant producing chemicals.
Define allelochemicals.
Secondary compounds of plant origin that interact with their environment and possess allelopathic properties.
What is true type allelopathy?
Toxic compounds are released into the environment in the form they are produced in.
What is functional type allelopathy?
Substances are released into the environment that becomes toxic due to microorganism transformation.
What are the 4 mechanisms of allelopathy release?
Volatilisation, leaching, exudation and decomposition.
What are some methods of ‘attack’ and ‘defence’ in fungi?
Antagonism, hyphal interference, mycoparasitism and gross mycelial contact.
What does antagonism involve?
Upregulation of enzymes, the C + N metabolism and stress mitigation metabolites.
What are the 4 outcomes of fungal interactions?
Deadlock, replacement, partial replacement and mutual replacement.
What impacts fungal interaction outcomes?
Venue, microclimate, resource quantity/quality, other microorganisms and invertebrate grazing.
What are bacterivores?
Fungi that utilise bacteria as a major nitrogen source.
What is Gause’s principle?
“Two or more species having identical patterns of resource use cannot coexist. One species will be better adapted and will out-compete the other”
