Abnormal spores and possible interspecific hybridization as a factor in the evolution of Early Devonian land plants

Abstract

Abnormal meiosis occurred in some land plants around 410 million years ago as witnessed by Early Devonian fossil spores from England. The spores have identical sculpture but occur in tetrad, triad, dyad and monad configurations. In that the same spore configurations occur in Ceratopteris and other modern fern hybrids the presence of similar variation in fossils may indicate the presence of hybridization amongst some Early Devonian plants. If so reticulate evolution, interspecific hybridization followed by polyploidy, may have played a significant role in the evolution of terrestrial plants in the early critical phases of their development.