Thorson's rule

Ecogeographical rule describing reproductive strategies of marine invertebrates

Thorson's rule is an ecogeographical rule which states that benthic marine invertebrates at low latitudes tend to produce large numbers of eggs developing to pelagic and widely dispersing larvae, whereas at high latitudes such organisms tend to produce fewer and larger lecithotrophic (yolk-feeding) eggs and larger offspring, often by viviparity or ovoviviparity, which are often brooded.

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