sustentative

These causes may be conveniently divided as in the above diagram, into sustentative and non-sustentative.

They are the victims of lethal natural selection, nearly always of the non-sustentative type.

But it must not be supposed that lethal, non-sustentative selection works only through forms of infant mortality.

For this reason alone the non-sustentative form of selection might be expected to be the predominant kind.