why might many speciation events happen comparatively rapidly in terms of morphological divergence, but then subsequently persist as a species for long periods without apparently changing very much morphologically?

one is through turgidity. this occurs before ground tissue ( collenchyma

and sclerenchyma cells) become well

developed to give structural support to the plant as it grows bigger. the xylem

tissue (composed of rigid tissue) of the young

plant render this support and also maintaining osmotic turgidity of the surrounding

plant cells.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.