The ecological species concept defines a species as a group of interrelated organisms that occupy or adapt to a single niche. For example, if a population of birds exploits two different food sources, it represents two d... More »

Symbiotic relationships on the tundra include nematode parasitism on caribou, bacterial mutualism with pitcher plants and nematode commensalism on black flies. Symbiosis is long-term dependence of one species on another ... More »

The phylogenetic species concept defines a species as a group of organisms that shares a common ancestor and can be distinguished from other organisms that do not share that ancestor. As an analogy, the phylogenetic spec... More »

The phrase "ontogeny recapitulates phylogeny" refers to a scientific theory that an organism's fetal development follows the species' previous evolutionary forms. This theory has been disproven. More »

Ecological balance is a theory stipulating that natural conditions, including numbers of various animal and plant species, remain stable on their own through variations over time. The theory, also known as balance of nat... More »

The scientific or botanical name of a flower depends on the specific type of flower and its species. For example, the genus for the rose is Rosa, and it belongs to the family called Rosaceae. More »

The biotic, or living, factors in the tropical rainforest include hundreds of thousands of species of plants, animals, bacteria and fungi. Rainforests are noteworthy for the incredible abundance of species that live in t... More »

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