Phenotypic diversification and island evolution of pipistrelle bats (Pipistrellus pipistrellus group) in the Mediterranean region inferred from geometric morphometrics and molecular phylogenetics

Abstract

Aim The Mediterranean Basin is a centre of radiation for numerous species groups. To increase our understanding of the mechanisms underlying speciation and radiation events in this region, we assessed the phenotypic variability within the Pipistrellus pipistrellus-pygmaeus-hanaki species complex. Although bats form the second largest mammalian order, studies of insular evolution in this group are scarce. We approached this problem from a microevolutionary perspective and tested for the recurrence of the insular syndrome.Location The Mediterranean Basin, with a special focus on isolated populations from Corsica, the Maghreb, Cyprus, Cyrenaica and Crete.Methods Phenotypic variability was assessed by cranial morphometrics using the coordinates of 41 3D landmarks and associated geometric-morphometric methods. We analysed 125 specimens representing all of the lineages in the species complex. Differences between taxa and between insular and continental populations in cranial size, shape, form and allometries were tested using analyses of variance and visualized using boxplots and canonical variate analysis. Relationships between molecular data from a previous study (cytochrome b sequences) and morphometric data were tested with co-inertia analyses (RV test) and multivariate regressions. ResultsThe three species were relatively well differentiated in cranial size and shape, and each species showed a significant amount of inter-population variability. Comparisons of pairs of insular versus continental populations revealed heterogeneities in cranial patterns among island phenotypes, suggesting no recurrent insular syndrome. Molecular and phenotypic traits were correlated, except for molecular and lateral cranium shape. Main conclusionsThe Pipistrellus pipistrellus-pygmaeus-hanaki species complex exhibits phenotypic variability as a result of the fragmentation of its distribution (especially on islands), its phylogenetic and phylogeographic history and, most probably, other evolutionary factors that were not investigated in this study. We found no recurrent pattern of evolution on islands, indicating that sitespecific factors play a prevailing role on Mediterranean islands. The correlation between molecular and phenotypic data is incomplete, suggesting that factors other than phylogenetic relationships, potentially connected with feeding ecology, have played a role in shaping cranial morphology in this species complex.

Cryptic diversity of Italian bats and the role of the Apennine refugium in the phylogeography of the western Palaearctic

“…The stepping‐stone dispersal between the Maghreb and the central Mediterranean region and a radiation zone of P. pipistrellus on islands of the Mediterranean Basin could be an example of such a strategy. Nascent phenotypic diversification within this species complex, presumably connected with selection, especially related to trophic niches, was revealed using geometric morphometrics (Evin, Horáček & Hulva, ). Elevated gene flow may be also demonstrated through broad sympatry, which has developed between both continental lineages of presumably Mediterranean origin ( P. pipistrellus and Pipistrellus pygmaeus ), and is mirrored in their demographic characteristics including star‐like phylogeny and other traces of population growth (Hulva et al ., ).…”

Photogrammetry: a useful tool for three-dimensional morphometric analysis of small mammals

“…Recently, some studies on the craniofacial form of different species of small mammals have employed 3D data (Evin et al. ; Cornette et al. ; Martínez‐Abadías et al.…”

An Analysis ofMyotis peninsularis(Vespertilionidae) Blending Morphometric and Genetic Datasets

“…In isolated areas, such as islands, bats may exhibit dwarfism in comparison with their continental counterparts (Case, 1978) in its morphological characters (Caumul and Polly, 2005;Evin et al, 2011;Marchán-Rivadeneira et al, 2012). The Baja Cali fornia group fits this pattern as a group with geographical isolation.…”

“…The Baja Cali fornia group fits this pattern as a group with geographical isolation. The geometric morphometrics of the skull shows that the specimens have a smaller size among other subspecies of M. velifer, as the Pipistrellus pipistrellus-pygmaeus-hanaki spe cies complex in the Mediterranean region (Evin et al, 2011).…”