Plant evolution

It includes the study of genetic change and the consequent variation that often results in speciation, one of the most important types of radiation into taxonomic groups called clades.

One major difference is the totipotent nature of plant cells, allowing them to reproduce asexually much more easily than most animals.

[2] However, the ecosystem structure is significantly rearranged, with the abundances and distributions of different groups of plants changing profoundly.

[2] During embryogenesis, plants and animals pass through a phylotypic stage that evolved independently[3] and that causes a developmental constraint limiting morphological diversification.

Unexpected ancient genome duplications have recently been confirmed in mustard weed/thale cress (Arabidopsis thaliana) and rice (Oryza sativa).

Cyanobacteria remained principal primary producers throughout the Proterozoic Eon (2500–543 Ma), in part because the redox structure of the oceans favored photoautotrophs capable of nitrogen fixation.

[citation needed] Green algae joined blue-greens as major primary producers on continental shelves near the end of the Proterozoic, but only with the Mesozoic (251–65 Ma) radiations of dinoflagellates, coccolithophorids, and diatoms did primary production in marine shelf waters take modern form.

[21] Charles Darwin in his 1878 book The Effects of Cross and Self-Fertilization in the Vegetable Kingdom[22] at the beginning of chapter XII noted “The first and most important of the conclusions which may be drawn from the observations given in this volume, is that generally cross-fertilisation is beneficial and self-fertilisation often injurious, at least with the plants on which I experimented.” Flowers emerged in plant evolution as an adaptation for the promotion of cross-fertilisation (outcrossing), a process that allows the masking of deleterious mutations in the genome of progeny.