How Species Interact with Each Other Environmental Science Spring 2011

Objectives Explain the difference between niche and habitat Give examples of parts of a niche Describe the five major types of interactions between species Explain the difference between parasitism and predation Explain how symbiotic relationships may evolve

Niche Niche: the unique role of a species within an ecosystem Includes: Species’ physical home Environmental factors necessary for species’ survival All of species’ interactions with other organisms

Species Interactions 5 major species interactions: Competition Predation Parasitism Mutualism Commensalism

Competition Competition: different individuals or populations attempt to use the same limited resources Can occur within and between species

Competition Indirect Competition: Species can compete even if they never come into direct contact Using the same plant for food at different times of the day

Competition Adaptations to Competition: When 2 species with similar niches are placed together, one species will usually be more successful Better adapted species would be able to use more the resources Adaptations that decrease competition will also be advantageous for species whose niches overlap

Competition Adaptations to Competition: Niche restriction occurs when each species uses less of the niche than it is capable of using Closely related species that use the same limited resources within habitat

Predation Predation: predator, prey interactions Predator: organism that feeds on another organism Prey: organism that is fed on Most organisms have evolved some mechanisms to avoid or defend against predators When predators only eat specific types of prey the sizes of each population tend to increase and decrease in linked patterns

Parasitism Parasitism: relationship between parasite and host Parasite: organism that lives in or on another organism and feeds on it Host: organisms the parasite takes its nourishment from Parasites usually do not kill their hosts Advantage if lets host live for a long time

Mutualism Mutualism: close relationship between two species n which each species provides a benefit to the other Ex. Humans and bacteria

Commensalism Commensalism: relationship in which one species benefits and the other species is neither harmed nor helped Ex. Birds nesting in trees

Symbiosis and Coevolution Symbiosis: relationship in which two species live in close association Many types of species interactions are considered symbiotic Often used to describe a relationship in which at least one species benefits

Symbiosis and Coevolution Coevolution: species in close relationships evolve together May evolve adaptations that reduce harm or improve the benefit of the relationship Ex. Flowering plants and their pollinators

Types of Interactions Between Two Species InteractionSpecies ASpecies BDescription CompetitionHarmed Each species negatively affects the other PredationBenefitedHarmedSpecies A feeds on species B ParasitismBenefitedHarmedSpecies A feeds on species B MutualismBenefited Each species is helpful to the other CommensalismBenefitedUnaffectedSpecies A benefits from species B, but species B is unaffected

Review Assignment Create a book that includes the 5 species interactions. 1 species interaction per page, title page For each interaction include: If species A and B are harmed, benefited, or unaffected (2 points) A description of the interaction (4 points) An example with picture (2 points) Unique or extra information (2 points) 5 points for neatness, creativity, organization Total points = 55 points