DSSS - The mechanisms and their evolvability: linking the micro- to macroevolutionary biology

Our understanding of evolution focuses either on small modifications, segregating within a population, or on large differences, only observed among higher taxa. How the former transform into the latter remains a largely unsolved question.

The potential for evolutionary change is anchored in the amount and the pattern of viable heritable variation that organisms can produce, and thus in how genetic changes translate into phenotypic change, the GP map. The GP map's structure and its consequences are well-studied conceptually; studies of modularity or robustness are good examples. We also know that GP map structure evolves over longer time spans, changing the patterns of variation that can be produced. Yet even modeling these, crossing the divide from micro to macro is not obvious. More empirical input on GP maps appears necessary.

Here, I will show that drawing on knowledge of developmental and physiological system structures, we can derive that the GP map is not unitary across traits but rather a mosaic of maps with distinct evolvabilities. This insight helps accommodate both variable and conserved processes and, in particular, offers a way to consider their interaction. The latter is crucial, as the conserved processes impose boundaries on the evolvability of variable ones, and a change in variability requires a change of those boundaries. While this approach is far from being mathematically operationalized, I will illustrate how we employ these principles in thinking about the reproductive evolution of mammals.