Topic 17 - Population Cycles Competition (BIOL 2300)

intraspecific competition

an interaction between individuals of the same species brought about by a shared requirement for a resource in limited supply (demand > supply)

interspecific competition

an interaction between individuals of different species

negative effect on both species - each species contributes to the ______ of the other _______ as well as its own

regulation, population

fundamental niche

full range of conditions and resources needed by a species to grow, survive and reproduce

• competition restricts a species to a portion of its fundamental niche

realized niche

portion of the fundamental niche a species actually uses as a result of competition

• may/may not occupy the part of fundamental niche allowing highest growth/reproduction (fitness)

niche overlap

when 2+ species use a portion of same resource (e.g. food, habitat) simultaneously

• amount of overlap ~ degree of potential competition

3 possible outcomes of competition (when one species is introduced to an area where another species exists)

1. coexistence without competition (not limited)

2. coexistence with competition (moderately limited) - results in reduction in one or both pops. 

3. one species is eliminated (very limited)

asymmetrical competition

one species is more strongly affected

• competitively dominant - species least affected by competiton

resource competition

each species uses a different portion of same resource → can reduce competition among co-occurring species

competitive exclusion principle

two species with the same resource requirements cannot coexist when those resources are limited (supply < demand)

Lotka-Volterra model for Interspecific Competition

• extension of the logistic equation

• differential equations (dN/dt) express the rate of non-linear growth of populations of competing species