Expanding the View of Emergence in Individuals, Populations, and Species of Stipoid Grasses: A Comparison Including Achnatherum occidentale

In our ongoing studies of emergent properties at different hierarchical levels in the grass tribe Stipeae, an additional species, Achnatherum occidentale, is included to broaden the comparison. The degree of emergence seen parallels that of previous studies, an increasing trend from populations to individuals and species to related groups of species. The degree of emergence in species pairs that hybridize, A. hendersonii and A. lemmonii, or A. occidentale and A. lemmonii, is lower than in non-hybridizing species pairs of Achnatherum, including the closely related pair of A. wallowaensis and A. hendersonii. The degree of emergence assesses the relationship among variables. This relationship, in turn, is the end product of integrated developmental pathways; a lower degree of emergence reveals similar responses among developmental pathways. Similar developmental responses may facilitate hybridiz a-