Decoding the evolution of species

Self-evolving materials based on metastable-to-stable crystal transition of a polymorphic polyolefin

Living organisms can self-evolve with time in order to adapt to the natural environment. Analogically, self-evolving materials also show similar properties based on non-equilibrium structural transformation. The common design of these materials tends to rely on solutions and hydrogels, yet only little attention has been paid to dry materials. To break this limitation, a new principle for developing self-evolving materials from a commercialized polymorphic polyolefin via programmable crystal transition is proposed. The self-evolving materials can encode information on patterns and morphing by the metastable crystal phase. Dynamically, this phase transforms to the stable crystal phase so that the encoded information self-evolves with time, displaying the autonomous characteristic. Moreover, this process can be interrupted at an arbitrary time through solvent-induced recrystallization. These advantages have been demonstrated by fabricating an edible period indicator and imitating sophisticated human body language. It is believed that this work may inspire future research studies on self-evolving materials based on the non-equilibrium process of dry materials.

A functional enrichment test for molecular convergent evolution finds a clear protein-coding signal in echolocating bats and whales

Distantly related species entering similar biological niches often adapt by evolving similar morphological and physiological characters. How much genomic molecular convergence (particularly of highly constrained coding sequence) contributes to convergent phenotypic evolution, such as echolocation in bats and whales, is a long-standing fundamental question. Like others, we find that convergent amino acid substitutions are not more abundant in echolocating mammals compared to their outgroups. However, we also ask a more informative question about the genomic distribution of convergent substitutions by devising a test to determine which, if any, of more than 4,000 tissue-affecting gene sets is most statistically enriched with convergent substitutions. We find that the gene set most overrepresented (q-value = 2.2e-3) with convergent substitutions in echolocators, affecting 18 genes, regulates development of the cochlear ganglion, a structure with empirically supported relevance to echolocation. Conversely, when comparing to nonecholocating outgroups, no significant gene set enrichment exists. For aquatic and high-altitude mammals, our analysis highlights 15 and 16 genes from the gene sets most affected by molecular convergence which regulate skin and lung physiology, respectively. Importantly, our test requires that the most convergence-enriched set cannot also be enriched for divergent substitutions, such as in the pattern produced by inactivated vision genes in subterranean mammals. Showing a clear role for adaptive protein-coding molecular convergence, we discover nearly 2,600 convergent positions, highlight 77 of them in 3 organs, and provide code to investigate other clades across the tree of life.