My Home is Yonder: Where I am
Epigenetics is showing us that we are bound to our environment
Atree maintains a memory of its origin, helping it to adapt to its local conditions. Each tree seed contains DNA, the genetic blueprint of the tree, along with carbohydrates for the developing embryo and a seed coat for protection. DNA is not the only factor in determining what the tree will look like: chemicals bound to the DNA also influence how the tree looks and functions. These chemicals are the ‘epigenome,’ and they turn genes on or off like a light-switch.
The epigenome maintains a ‘record’ of inherited experiences. The ‘position’ of the DNA switch, whether ‘on’ or ‘off,’ is passed on to offspring. As trees cannot run from bad environments, and spend a great deal of energy reproducing to disperse their offspring to better novel environments. In this way, trees are masters at adaptation.
This DNA blueprint was noticeable in a recent Norwegian spruce tree reforestation programme culminating in around 2013 trees were copied through grafting from northern Norway to orchards in the south of the country , and the new grafts were planted into the new southern location. After the trees matured, seeds were collected and planted back in the original northern area. Unexpectedly, the growth rhythms of the seeds from the new southern orchards were more in tune with the day lengths and temperatures of the southern environment, and accordingly were not suitable for planting in the northern part of the country.
The genes of the spruce trees had been trumped by the effects of the epigenome, a concrete example of epigenetics working alongside natural selection to provide an additional mechanism for trees to adapt to their environment. In a new climate, seeds received environmental cues that allowed them to adjust to their ability to grow.
This meant, and means that when replanting seeds there is only a limited area in which the planting might work in the long-term, and taking seed outside of these climatic and geographical zones is not conducive to a successful forestation programme.
a place like home
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