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Fig. 8 | Biology Direct

Fig. 8

From: Tradeoff between robustness and elaboration in carotenoid networks produces cycles of avian color diversification

Fig. 8

Hypothetical scenarios for historical association between elongation and robustness in carotenoid pathways. Biochemical scope is the total biochemical space (in compounds) potentially reachable from a dietary carotenoid based on its chemical connectivity, measured in the number of consecutive reactions (numbered nodes in circles above; Methods). The metabolic elaboration scenario (left) predicts stepwise colonization of biochemical scope and continuous elongation of metabolic pathway from the same dietary carotenoid within a lineage. Dietary entry points differ among lineages (Species 1-5), such that elaboration occurs within a biochemical scope of a particular dietary compound. The exploration of dietary vicinity scenario (middle) predicts limited elongation (small occupancy of biochemical scope) around dietary carotenoids. This scenario also predicts lineage-specific biochemical scope, but with less metabolic elongation. The coevolution of elaboration and robustness scenario (right) predicts that acquisition of additional dietary paths enables ongoing elaboration, such that within a lineage, longer pathways should be associated with sequentially gained paths to new dietary carotenoids, so that greater elongation is associated with greater diversity of biochemical scopes that contributes to it, even within a lineage

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