Impact of transition to a subterranean lifestyle on morphological disparity and integration in talpid moles (Mammalia, Talpidae)

Abstract

Background Understanding the mechanisms promoting or constraining morphological diversification within clades is a central topic in evolutionary biology. Ecological transitions are of particular interest because of their influence upon the selective forces and factors involved in phenotypic evolution. Here we focused on the humerus and mandibles of talpid moles to test whether the transition to the subterranean lifestyle impacted morphological disparity and phenotypic traits covariation between these two structures. Results Our results indicate non-subterranean species occupy a significantly larger portion of the talpid moles morphospace. However, there is no difference between subterranean and non-subterranean moles in terms of the strength and direction of phenotypic integration. Conclusions Our study shows that the transition to a subterranean lifestyle significantly reduced morphological variability in talpid moles. However, this reduced disparity was not accompanied by changes in the pattern of traits covariation between the humerus and the mandible, suggesting the presence of strong phylogenetic conservatism within this pattern.

Decoupling Functional and Morphological Convergence, the Study Case of Fossorial Mammalia

“…We built synthetic phylogenies, presented in Supplementary Figure S2, in Mesquite 3.02 (Maddison and Maddison, 2015). The stratigraphic range and phylogenetic position have been derived from the most updated literature (Piras et al, 2015;Sansalone et al, 2019). Supplementary Table S1 includes the complete literature corpus employed to build the phylogenetic trees.…”

“…Supplementary Table S1 includes the complete literature corpus employed to build the phylogenetic trees. We built two different phylogenies because of the lack of agreement between molecular and morphological data for talpids (see Sansalone et al, 2019, for an extensive discussion about the topic). For Mesoscalops, we used the data presented by Gunnel et al (2008) and Barnosky (1981).…”

“…Fossorial mammals have often been reported as a textbook example of convergent evolution (Nevo, 1979;Hildebrand et al, 1985). The subterranean environment is relatively predictable in time, and requires a high degree of specialization, which in turn can lead to comparable morphological forms (Nevo, 1979;Marcy et al, 2016;Sansalone et al, 2019). Moreover, locomotion underground requires extreme morphological specialization and digging kinematic is likely to have a strong impact on other functional traits (Piras et al, 2012(Piras et al, , 2015Sansalone et al, 2018).…”

Myoglobin primary structure reveals multiple convergent transitions to semi-aquatic life in the world’s smallest mammalian divers

“…Finally, semi-fossorial shrews, solenodons, and shrew moles exhibit specializations inbetween that of terrestrial and fossorial lineages, often retaining pointed mouse-like snouts yet possessing forelimbs that are oriented downwards and backwards to facilitate digging (Gorman and Stone 1990;Nowak 1999). While the lifestyle of extant eulipotyphlan mammals is easily predicted based on external morphological features alone (e.g., Woodman and Gaffney 2014;Sansalone, et al 2016;Sansalone, et al 2019), definitive assignments of transitional evolutionary stages have remained elusive due to an incomplete, fragmentary fossil record (Hickman 1984;Sá nchez-Villagra, et al 2006;Piras, et al 2012;Hooker 2016). Additionally, because morphological specializations coincide with lifestyle across the different clades of eulipotyphlan mammals, it has been difficult to discern whether fossorial and semi-aquatic specializations found in Eurasian and North American moles arose in a common ancestor or are due to convergent evolution (Schwermann and Thompson 2015;He, et al 2017).…”

Current Options for Visualization of Local Deformation in Modern Shape Analysis Applied to Paleobiological Case Studies

“…GM is being routinely used to address a wide spectrum of hypotheses. In particular, the use of shape analysis has been fruitfully coupled with phylogenetic comparative methods in order to explore patterns of convergence/divergence (Stayton, 2015;Castiglione et al, 2019), morphospace occupation (Santos et al, 2019), morphological integration (Piras et al, 2014;Sansalone et al, 2019), functional hypothesis (Oxnard and O'Higgins, 2009), and developmental growth (Angulo-Bedoya et al, 2019;Colangelo et al, 2019). All these studies share the same basic source of phenomenological interpretation: the shape change studied via shape analysis (very often GM).…”