The Relationship Between Adult Size and Brooding in Marine Invertebrates

Greater brood care is associated with smaller adult size in co-occurring benthic marine invertebrates of many but not all taxa. A review of the literature suggests that the reverse trend is rare. 2. Varied hypotheses can be advanced for the association of small adult size with greater brood care. The hypotheses concern allometry of egg production and brood capacity, longevity with repeated reproduction and variable recruitment, and dispersal. The hypotheses are not mutually exclusive and more than one explanation could apply to most of the reported cases of smaller adults associated with greater brood care. 3. None of the explanatory hypotheses which have been advanced fits all reported cases of greater brooding with smaller adult size, and life history correlates of both adult size and brood care are numerous. Thus the trend may result from selection for different life history traits in different taxa.