Evidence of positive selection on six spider developmental genes

Abstract

Spiders constitute more than 49,000 described species distributed all over the world, and all ecological environments. Their order, Araneae, is defined by a set of characteristics with no parallel among their arachnid counterparts (e.g., spinnerets, silk glands, chelicerae that inoculate venom, among others). Changes in developmental pathways often underlie the evolution of morphological synapomorphies, and as such spiders are a promising model to study the role of developmental genes in the origin of evolutionary novelties. With that in mind, we investigated changes in the evolutionary regime of a set of six developmental genes, using spiders as our model. The genes were mainly chosen for their roles in spinneret ontogeny, yet they are pleiotropic, and it is likely that the origins of other unique morphological phenotypes are also linked to changes in their sequences. Our results indicate no great differences in the selective pressures on those genes when comparing spiders to other arachnids, but a few site‐specific positive selection evidence were found in the Araneae lineage. These findings lead us to new insights on spider evolution that are to be further tested.

Molecular and Developmental Signatures of Genital Size Macro-Evolution in Bugs

“…This is consistent with a scenario where the majority of changes in genital size have been possible due to a relaxation of purifying selection in developmental genes rather than by persistent positive selection. In fact, this scenario is probably more often the rule then the exception due to the highly pleiotropic nature of the morphogenetic genes ( Partha et al 2017 ; Womack et al 2018 ; Mariano-Martins et al 2022 ). From our dataset, illustrative examples are the transcription factors escargot , cabeza , and homothorax .…”

Biomedical applications of silk and its role for intervertebral disc repair

“…Many insects and arachnids produce silk biopolymers as a protective shield during their life, such as the silkworms (Insecta: Lepidoptera: Bombycidae), 24 spiders (Chelicerata: Arachnida), 25 mites (Chelicerata: Arachnida: Acari: Tetranychidae), 26 and wasps (Insecta: Hymenoptera). 27 The most popular type of silk, mulberry silk, accounts for most silks produced globally (about 95%) (Figure 1 ).…”