Variation among tripsacum populations of Mexico and Guatemala

摘要: Seven species of the genusTripsacum, one with a well marked subspecies, are indigenous to Mexico and Guatemala. Two diploids,T. zopilotense andT. maizar, restricted western southwestern Mexico. The typical diploid form third species,T. latifolium, occurs in south central eastern Guatemala; atypical tetraploid forms this found Four tetraploids,T. dactyloides, T. dactyloides ssp.hispidum, lanceolatum, pilosum, have ranges extending from northwestern southeastward into seventh is highly sterile tetraploid,T. laxum, doubtful occurrence wild. It readily propagated vegetatively has been widely distributed Latin America West Indies as forage plant. Field studies range variation 80 Mexican Guatemalan populations included an evaluation 16 definitive morphological characteristics average approximately six individuals each population. Seventy-three were allopatric, these, 50 classed typical, 13 atypical, ten intermediates. Thirty-nine tetraploid, 11 diploid. Of 23 intermediate populations, 17 Fifty-eight which ofT. comprised inclusive intergrading series having different combinations distinguishing two very dissimilar mizar zopilotense. This was interpreted support for hypothesis Randolph & Hernandez (1950), that originated alloploid derivatives these or closely related species. some not seen either putative parental noted, possibility other taxa also might involved their origin under investigation. In addition 73 allopatric survey there seven sympatric mixed associations taxa. Among hybrids various differentiating associated populations. These effectively obscured differences between taxa, thus creating syngameon complex genetic recombinants observed spread recently disturbed habitats neighboring areas. From such direct evidence, existing interrelationships among it concluded tetraploidTripsacum variants, involved, continuing involve, complexes, those encountered examples.