I love varigated plants and have a ton of them. I’m continually amazed at what leaves manage to survive if they’re not completely white, and sometimes those white leaves just hang on longer than they should. Please ELI5, someone how these zombie creatures survive and flourish?
Took me 2 years to notice this post, but I had a look at some of the literature…
For a 5 year old… I would probably tell them that a plant is not in a natural environment to begin with, and that the amount of light that it is exposed to in a house is not necessarily the amount of light that it is adapted for. Yet, it can survive. Perhaps the optimal conditions make it grow better and produce stronger seeds, but the plant can still survive if the conditions are not optimal. The same might happen with a leaf - parts of the leaf might not absorb as much light, but it can still survive. If something helps it reproduce - maybe humans like them more and breed them, or insects eat them less in nature, the plant can survive even if it is less efficient in collecting light.
… But, for a 6 year old, I would point them to some examples in the literature that describe at least 4 types of variegation - some due to a difference in the amount of chloroplast-containing layers, others with a difference in chloroplast content within those layers, others that look variegated not due to less chloroplast but due to having a higher reflectance over the full visible spectrum due to larger air pockets within the larger cells, and some due to having additional (often anthocyanin) pigments.
It is sometimes the case that photosynthetic efficiency is lower, but not actually always the case. In the cases when photosynthetic efficiency is lower, the loss in efficiency is balanced by some selective pressure. For example, a slower growth may be acceptable if the variegation deters leaf miner insects from depositing eggs (because the leaf looks as if the leaf has already been mined), or the leaf may naturally grow in an environment in which the decrease in photosynthetic efficiency is actually desired.
This info comes primarily from: The fine structure and photosynthetic cost of structural leaf variegation
I found another case in Arabidopsis. This paper talks about a mutation in Arabidospsis that basically destroys chloroplasts due to redox damage: Photosynthetic Redox Imbalance Governs Leaf Sectoring in the Arabidopsis thaliana Variegation Mutants immutans, spotty, var1, and var2
