This is Dawkins' idea of "extended phenotype". Normally a gene's phenotype refers to its effects on the body of an individual organism posessing that gene, like hair colour or immune response.
A gene's extended phenotype includes effects external to particular organisms, like nests, deforestation, changes to the chemical makeup of the atmosphere, etc.
1) Trees are natural and trees create leaves with a solar efficiency of x
2) Humans are natural and we create solar panels with efficiency x + y