The Information Value of Non-Genetic Inheritance in Plants and Animals
Figure 1
Inheritance pathways and model framework.
A. Different pathways of inheritance, including (a) direct germline transmission between germ cells (GC) across generations (e.g inheritance of DNA or DNA methylation marks due to incomplete resetting); (b) effect of parental phenotype on germ cells of next generation (e.g. environmentally-induced changes in methylation status in early embryos); (c) effect of parental phenotype on offspring phenotype (e.g. large mothers producing large offspring); (d) effects of parental phenotype on offspring environment (dotted box) (modified in part from [11]). B. The model framework: evolution of a developmental switch that can respond to three sources of input, genetic loci (G), maternal phenotype (M), and environment (E). All three sources of input can carry information as follows (left hand side, from top to bottom). First, at the outset, G arises by a random process (e.g. mutation from Gā ā G) and leads to, and correlates with, phenotype Pi; after one or several rounds of selection, G correlates both with Pi and with some environmental factor(s) experienced by the offspring ES in virtue of which G was selected. Second, the maternal phenotype can carry correlational information about the selective regime in ES if it correlates with G and/or if the maternal environment that influences the expression of M (EM) shows autocorrelation with the environment of the offspring at the time of selection (ES). Finally, the environment of development (ED) can carry correlational information about the environment of selection (ES). Note that figure B omits additional links arising from, for example, niche construction, where ancestors affect Es directly [5] and genetic differences that cause variation in parental contribution to offspring (e.g. [83]). All three sources of input can affect the liability of a developmental switch (thick black arrows), which in response can produce a range of phenotypes (grey arrows), Pi (here i = 2). Phenotypes are subject to selection (dashed box) as a result of variation in the environment (ES). Thus, adaptive evolution of the developmental switch is expected to increase the match between phenotype, Pi, and the selective environment, ES, by modifying the response to genetic, maternal, or environmental input.