Species compete for almost every conceivable kind of resource, and the same two species may compete for different resources in different environments. Hole-nesting birds compete for tree holes, plant species compete for pollinators and seed dispersers, and male birds compete for preferred sites to defend as territories for attracting females. Species may compete for many resources simultaneously, but often one resource, called the limiting resource because it limits the population growth of each species, is the focus of competition. Moreover, the ways in which species compete vary with the resources. In some cases, species compete by capturing resources faster than their competitors (exploitation competition). Some plant species, for example, are able to extract water and nutrients from the soil faster than surrounding species. In other cases, the two species physically interfere with one another (interference competition) by aggressively attempting to exclude one another from particular habitats.
Transfer-of-energy-through-an-ecosystemFigure 2: Transfer of energy through an ecosystem. At each trophic level only a small proportion of …[Credits : Encyclopædia Britannica, Inc.]
Generalized-aquatic-food-webFigure 1: Generalized aquatic food web. Parasites, among the most diverse species in the food web, …[Credits : Encyclopædia Britannica, Inc.]
Male-resplendent-quetzal-or-resplendent-trogonMale resplendent quetzal, or resplendent trogon (Pharomachrus mocinno).[Credits : Michael & Patricia Fogden]
Parasitoids-which-parasitize-other-arthropods-by-depositing-eggs-in-theFigure 2: Parasitoids, which parasitize other arthropods by depositing eggs in the pupae, larvae, …[Credits : Encyclopædia Britannica, Inc.]
DOrbignys-round-eared-bat-capturing-a-katydid-in-flightD’Orbigny’s round-eared bat (Tonatia silvicola) capturing a katydid in flight.[Credits : © Merlin D. Tuttle, Bat Conservation International—Photo Researchers, Inc.]
Silky-anteater-extending-its-long-narrow-tongue-which-it-usesSilky anteater (Cyclopes didactylus) extending its long, narrow tongue, which it uses to …[Credits : Gunter Ziesler/Bruce Coleman Ltd.]
Coevolution-between-the-yucca-moth-and-the-yucca-plantCoevolution between the yucca moth and the yucca plant. (Top) A female yucca moth …[Credits : Photographs, © Robert and Linda Mitchell]Coevolution between the yucca moth and the yucca plant. (Top) A female yucca moth …[Credits : Photographs, © Robert and Linda Mitchell]
Coevolution-of-one-species-with-many-speciesCoevolution of one species with many species. (Top) European cuckoo (Cuculus canorus) …[Credits : John Markham/Bruce Coleman Ltd.]Coevolution of one species with many species. (Top) European cuckoo (Cuculus canorus) …[Credits : John Markham/Bruce Coleman Ltd.]
We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.
Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.