noun
mutualism; symbiosis
Biology term for a relationship where both organisms benefit.
アリとアブラムシの関係は相利共生の一例だ。
The relationship between ants and aphids is an example of mutualism.
共生 is the broader term for symbiosis, which includes mutualism, commensalism, and parasitism. 相利共生 specifically refers to mutualism where both parties benefit.
Compound of 相利 (mutual benefit) and 共生 (symbiosis). The exact historical derivation is uncertain, but the term is a modern biological coinage.