A study of scorpion ecomorphs

 

Ecomorphs are groups of organisms that share a set of morphological traits associated with specific ecological requirements. They are created and shaped by environmental changes and adaptions to these. Scorpions have been assigned to ecomorphs for many years (mainly based on the microhabitat they use), but this assignment have never been properly tested.

Pedro Coelho and co-workers have now published a study on existence of scorpion ecomorphs by quantifying the association between their morphology and ecology across several species from many families. The study confirmed the existence of scorpion ecomorphs by showing associations between ecology and morphology.

Here are the scorpion ecomorphs that have been used for scorpions:

Psammophilous: Sand fossorials.

Phytophilous (Corticolous): Under vegetation, leaf-litter and other passive shelters.

Pelophilous: Hard soil fossorials.

Lithophilous: Rock climbers.

Abstract:
Background: Ecomorphs create the opportunity to investigate ecological adaptation because they encompass organisms that evolved characteristic morphologies under similar ecological demands. For over 50 years, scorpions have been empirically assigned to ecomorphs based on the characteristic morphologies that rock, sand, vegetation, underground, and surface dwellers assume. This study aims to independently test the existence of scorpion ecomorphs by quantifying the association between their morphology and ecology across 61 species, representing 14 families of the Scorpiones order.
Results: Without a priori categorization of species into ecomorphs, we identified four groups based on microhabitat descriptors, which reflect how scorpion ecospace is clustered. Moreover, these microhabitat groups, i.e., ecotypes, have significantly divergent morphologies; therefore, they represent ecomorphs. These ecomorphs largely correspond with the ones previously described in the literature. Therefore, we retained the names Lithophilous, Psammophilous, and Pelophilous, and proposed the name Phytophilous for vegetation dwellers. Finally, we sought to map the morphology-ecology association in scorpions and found that the morphological regions most tightly associated with ecology are at the extremities. Moreover, the major trend in ecomorphological covariation is that longer walking legs and relatively slender pedipalps (pincers) are associated with sandy microhabitats, while the inverse morphological proportions are associated with rocky microhabitats.
Conclusions: Scorpion ecomorphs are validated in a naïve approach, from ecological descriptors and whole bod anatomy. This places them on a more solid quantitative footing for future studies of ecological adaptation in scorpions. Our results verify most of the previously defined ecomorphotypes and could be used as a current practice to understand the adaptive significance of ecological morphology.

Reference:
Coelho P, Kaliontzopoulou A, Sousa P, Stockmann M, van der Meijden A. Reevaluating scorpion ecomorphs using a naïve approach. BMC Ecol Evol. 2022;22(1):17 [Open Access]

Thanks to Pedro Coelho for sending me their article!