Lecture 19 Flashcards
types of interactions
- trophic
- reproductive
- habitat-related
interspecific competition
competition between individuals of different species
intraspecific competition
competition between individuals of the same species
resource limitation
limited supply of food, space, etc, leads to interference and exploitative competition
interference competition
direct aggressive interaction between individuals
exploitative competition
competition to secure resources first
example of competition: self-thinning in plants
Over time there is competition for resources of nutrients –> less dense group of plants but on average each plant is larger because they were able to out-compete the others
example of competition: song sparrows
males of middle ages most likely to be challenged by “floaters” - way of looking at competition in terms of behaviour of individuals rather than morphological traits
why competition is more common in plants
- plants exist in higher densities
2. plants can’t move out of the way
competitive exclusion principle
2 species with the same niche cannot coexist indefinitely –> occupy different realized niches –> alter dimensions of fundamental niche
2 times when competitive exclusion doesn’t occur
- when disease and predation are bigger limiting factors
2. in extreme or highly variable environments (like lakes)
Tansley G. saxatile and G. pumilum experiment
when alone both species can grow in acidic or basic soil, together one outcompeted in acidic and other in basic - evidence for competitive exclusion
character displacement
changes in the physical characteristics of a species’ population as a consequence of natural selection for reduced interspecific competition
example of character displacement: stickleback
Broad range of gill rake lengths in lakes with multiple species, each species has a different distribution when existing together
