Transcript Natural selection and predator –prey interactions

Natural selection
predator–prey interactions
Ecological interactions between organisms
1) Competition(-/-)
two organisms using the same resources
-Interspecific competition : Competition between members of two or more
species.
-Intraspecific competition : Competition among members of a single species.
2) Predator-prey (+/-) (including herbivores/plants, parasite/host )
benefit itself while harming another
3) Mutualism(+/+)
Both participants benefit from an interaction
4) Commensalism(+/0)
One participant benefit while is unaffected
5) Amensalism(0/-)
One participant is harmed but the other is unaffected
Natural selection
(Adaptation)
•
Organisms interactions involve reciprocal changes over time. This kind of evolutionary is
termed co evolution. Change in one organism is selective force for counter adaptation by
the other such as predator prey interaction. Predators increase when prey are abundant, the
prey population decreases due to predation, as a result, the predators decline and the prey
populations begin to increase.
•
Traits( genetic makeup) that confer superiority in survival and reproduction to their owner.
•
Fitness- success among genotypes within population.Genes that benefit the population
spread quickly because those that carry them have greater reproductive success, leading
to changes in frequency of allele (evolution ).
Natural selection
* Fitness formula for predator
Wi= Ci/C
Ni/N
*Fitness formula for prey
Wi= ei/e
ni/ n
* 3 predator morph (same sp) and 4 prey sp
* 2 min capture period