Evolution of wing shape in geometrid moths: phylogenetic effects dominate over ecology.

Locomotory performance is an important determinant of fitness in most animals, including flying insects. Strong selective pressures on wing morphology are therefore expected. Previous studies on wing shape in Lepidoptera have found some support for hypotheses relating wing shape to environment-specific selective pressures on aerodynamic performance. Here, we present a phylogenetic comparative study on wing shape in the lepidopteran family Geometridae, covering 374 species of the northern European fauna. We focused on 11 wing traits including aspect ratio, wing roundness, and the pointedness of the apex, as well as the ratio of forewing and hindwing areas. All measures were taken from images available on the internet, using a combination of tools available in Fiji software and R. We found that wing shape demonstrates a phylogenetically conservative pattern of evolution in Geometridae, showing similar or stronger phylogenetic signal than many of its potential predictors. Several wing traits showed statistically significant associations with predictors such as body size, phenology, and preference for forest habitats. Overall, however, all of these associations remained notably weak, with no wing shape being excluded for any value of the predictors, including body size. We conclude that, in geometrids, wing traits do not readily respond to selective pressures optimizing aerodynamic performance of the moths in different environments. Selection on wing shape may nevertheless operate through other functions of the wings, with the effectiveness of crypsis at rest being a promising candidate for further studies.

Contrasting patterns at interspecific and intraspecific levels in scorpion body size across a climatic gradient from rainforest to dryland vegetation.

Body size is believed to be one of the most fundamental functional traits in animals and is evolutionarily conserved in order to guarantee the survival of the species. Besides the phylogenetic backgrounds, body size patterns might be a product of environmental filters, especially within fine taxonomic levels (i.e., within species or geographical lineages). Here, we evaluated the responses of scorpion body size at different organizational levels (inter and intraspecific) along a dry-wet climatic gradient in Brazilian forests. Scorpions were collected from 20 localities in northeastern Brazil, covering 12 sites of dry forests and eight sites in rainforest environments. As a proxy for body size, we measured the carapace length of 368 adult scorpions belonging to 11 species and applied linear mixed-effects models to investigate the potential effects of climatic features and geographical tendencies in this trait at inter- and intraspecific levels. Our findings suggest the existence of a longitudinal pattern of body size in scorpions with species becoming larger in an east-west direction (i.e., towards the continent); such geographical tendency was also detected for one of the three species analyzed at the population level. In addition, the warmer temperature had a negative effect on body size in scorpions at inter- and intraspecific levels. Based on these findings, we assert that body size in scorpions is not affected solely by their phylogenetic history, but also by the physiological constraints imposed by the environment, which becomes more evident across climatic gradients.