The evolution of endosymbiont genomes is likely influenced by the ecological interactions with their hosts. Here, we studied the evolution of Spiroplasma genomes detected within Morpho butterflies sampled in the wild. Spiroplasma was detected in 4 out of the 11 Morpho species studied and displayed a 3 times larger genome size as compared to Spiroplasma genomes documented in other hosts. This inflation in genome size is caused by massive and recent expansion of various mobile genetic elements and by the acquisition of new genes stemming from prophages. In particular, we documented the peculiar evolution of the toxin genes in plasmids that may enhance host resistance to parasites. Phylogenetic comparisons with Spiroplasma extracted from other host point at a unique origin of Spiroplasma in Morpho , and strong divergence from Spiroplasma found in other Lepidoptera. Resequencing data obtained for multiple populations of the two sister-species M. helenor and M. achilles living in sympatry over the majority of their distribution revealed a opposite prevalence (97% in M. achilles and 3% in M. helenor ), suggesting contrasted ecological interactions with these two host-species. Reconciliation analysis of the phylogenetic relationships of Morpho mitochondrial genomes and Spiroplasma genomes was then consistent with a predominant vertical transfer of the endosymbiont. Altogether, our results suggest a key role of ecological interactions with the host in the evolution of endosymbiont genomes and point at a putative interaction of Spiroplasma with reproductive isolation between sympatric species of butterflies. ### Competing Interest Statement The authors have declared no competing interest.

The fundamental value of universal nomenclatural systems in biology is that they enable unambiguous scientific communication. However, the stability of these systems is threatened by recent discussions asking for a fairer nomenclature, raising the possibility of bulk revision processes for "inappropriate" names. It is evident that such proposals come from very deep feelings, but we show how they can irreparably damage the foundation of biological communication and, in turn, the sciences that depend on it. There are four essential consequences of objective codes of nomenclature: universality, stability, neutrality, and transculturality. These codes provide fair and impartial guides to the principles governing biological nomenclature and allow unambiguous universal communication in biology. Accordingly, no subjective proposals should be allowed to undermine them.

La presente publicación que la Universidad Nacional de San Martín (UNSM) se complace en editar, constituye uno de los mejores esfuerzos por acercar el conocimiento especializado sobre un taxón cuya diversidad ha sido objeto de asombro, tanto de neófitos como entomólogos de reconocida trayectoria en el mundo. De entrada , los autores nos hacen una singular revelación: en el norte del Perú se encuentra la región más rica de Morpho “de toda la América tropical, con 15 especies y 25 subespecies presentes en un área formada por tan sólo los departamentos de San Martín y Amazonas”.

Assessing the relative importance of geographical and ecological drivers of evolution is paramount to understand the diversification of species and traits at the macroevolutionary scale. Here, we use an integrative approach, combining phylogenetics, biogeography, ecology and quantified phenotypes to investigate the drivers of both species and phenotypic diversification of the iconic Neotropical butterfly genus Morpho. We generated a time-calibrated phylogeny for all known species and inferred historical biogeography. We fitted models of time-dependent (accounting for rate heterogeneity across the phylogeny) and paleoenvironment-dependent diversification (accounting for global effect on the phylogeny). We used geometric morphometrics to assess variation of wing size and shape across the tree and investigated their dynamics of evolution. We found that the diversification of Morpho is best explained when considering variable diversification rates across the tree, possibly associated with lineages occupying different microhabitat conditions. First, a shift from understory to canopy was characterized by an increased speciation rate partially coupled with an increasing rate of wing shape evolution. Second, the occupation of dense bamboo thickets accompanying a major host-plant shift from dicotyledons towards monocotyledons was associated with a simultaneous diversification rate shift and an evolutionary 'jump' of wing size. Our study points to a diversification pattern driven by punctuational ecological changes instead of a global driver or biogeographic history.