where the green grass (and brown kiwis) grow

necklace by paula hayes ~ ring by AdornJewelry ~ terrarium by Greenbriar ~ charging station via iliketotallyloveit

i found a great article today (or rather, i read an article that i didn't realise i had in my endnote already) that just about made me pee my pants with excitement when i read this line:

"Furthermore, from these results it can be inferred that embryonic development is at least in part constrained by postnatal growth rate, so that any useful increase in assimilation can only be accomplished by a change in the pattern of organ development."

this not only supports some of my embryo results (or rather, my results support this statement), but should really boost my paper's relevancy in the whole grand scheme of things and add just that little bit of extra that i thought it was missing. at least i hope so!

the article compared embryological growth of two species with different patterns of postnatal growth and showed that these patterns became apparent even in early embryo stages. the early stages were thought to be conservative in that both altricial and precocial chicks start their growth in the same fashion and didn't diverge until later stages. however, so-called 'supply' organs, such as the digestive organs, grow faster in the early embryonic life of altricial birds in comparison to precocial birds. conversely, 'demand' organs, such as the locomotive organs, grow faster in precocials than altricials.

the article concedes that it is somewhat illogical to divide organs into 'supply' and 'demand' when they are all obviously necessary to survive. however, by dividing them as such, one can picture the competition between organs during embryological development and how this drives the developmental pattern in embryonic and postnatal life.

so not only does the postnatal growth rate (an inherent property of an organism) constrain embryonic growth, developmental mechanisms are also influenced by selection for late ontogenetic characters. the author points out that in kiwis and ostriches, who rely on their legs as their sole form of locomotion, the hindlimbs are longer than the forelimbs even in early development.

so basically, the size of the organs that characterise a precocial or altricial bird will dictate the way the embryo grows. i am interpreting this to mean that the relative importance of a feature in the chick will dictate the way it grows as an embryo, and this is why a highly specialised structure, like the kiwi's bill, grows very quickly even in relation to it's limbs.

...yeah... at least i think that's what's going on. better get it down on paper so the supervisors can check it out next week.
phyto purification bathroom via jeansnow


Popular Posts