premise: Animals with one copy of the mutant gene are physiologically normal, but when two such animals are mated, some of the embryos-embryos with two copies of the mutant gene-die in the womb.
hypothesis: Invertebrates (and higher animals) can also be placed in one of two groups based on how they develop as embryos.
hypothesis_graph_structure: Invertebrates (and higher animals<>can be placed<>$$$two groups<>based<>on how they develop as embryos$$$they<>develop<>