Interspecific Interactions

Interspecific Interactions

Ecology-Interspecific Interactions
Introduction
The niche is one of the most important concepts in ecology. In essence, an organism’s niche is how it makes a living: the environmental conditions it tolerates, the important resources it needs to survive, and its ways of obtaining those resources. In obtaining energy, nutrients, etc., populations of one species frequently interact with populations of other species. This leads us to discuss specific types of interactions between species.




Neutralism is the most common type of interspecific interaction. Neither
population affects the other.  Any interactions that do occur are indirect or
incidental.
Amensalism is when one species suffers and the other interacting species
experiences no effect.  This is sometimes viewed as a very asymmetric form of
competition.
Mutualism in an interspecific interaction between two species, that benefits both
members.  Populations of each species grow, survive and/or reproduce at a higher
rate in the presence of the other species.  Mutualisms are widespread in nature,
and occur among many different types of organisms.
Commensalism is an interspecific interaction where one species benefits and the
other is unaffected.  They are ubiquitous in nature.  For example, birds nesting in
trees are commensal.  Commensal organisms frequently live in the nests, or on the
bodies, of the other species.
Predators, parasites, parasitoids, and herbivores obtain food at the expense of
their hosts or prey.

• Predators tend to be larger than their prey, and consume many prey during their lifetimes.
• Parasites and pathogens are smaller than their host.  Parasites may have one or many hosts during their lifetime.  Pathogens are parasitic microbesmany generations may live within the same host.  Parasites consume their host either from the inside (endoparasites) or from the outside (ectoparasites).
• Parasitoids hunt their prey like predators, but lay their eggs within the body of a host, where they develop like parasites.
• Herbivores are animals that eat plants.  This interaction may resemble predation, or parasitism.

Competition occurs when organisms in the same community seek the same
limiting resource.  This resource may be prey, water, light, nutrients, nest sites,
etc.

• Competition among members of the same species is intraspecific.
• Competition among individuals of different species is interspecific.  

Individuals experience both types of competition, but the relative importance of the two types of competition varies from population to population and species to species
Types of Competition
Exploitation competition occurs when individuals use the same limiting
resource or resources, thus depleting the amount available to others.
Interference competition occurs when individuals interfere with the
foraging, survival, or reproduction of others, or directly prevent their
physical establishment in a portion of a habitat.