Phylogenetic relationships of Western Mediterranean subterranean Trechini groundbeetles (Coleoptera: Carabidae)

Abstract

Faille, A., Casale, A. & Ribera, I. (2010). Phylogenetic relationships of Western Mediterranean subterranean Trechini groundbeetles (Coleoptera: Carabidae). —Zoologica Scripta, 40, 282–295. Carabid beetles of tribe Trechini (Coleoptera) are one of the main groups of insects that colonized the subterranean environment. Many species of this group have developed similar morphological modifications related to the subterranean life, resulting in a characteristic Aphaenops‐like phenotype that obscures their phylogenetic relationships (depigmented, blind, elongated body and appendages, narrow head and pronotum). We present here the result of a molecular study using a combination of nuclear (small ribosomal unit, large ribosomal unit) and mitochondrial (cox1, cyb, rrnL, trnL, nad1) genes to investigate the phylogenetic placement of the highly modified subterranean genera of the tribe Trechini from the west Mediterranean area (France, Spain, Morocco and Sardinia). Our results confirm the multiple independent origin of troglomorphism among these genera, and reveal a pattern largely determined by geographical proximity. We discuss the validity of some groups proposed on the base of morphological features, and provide estimates of divergence between subterranean genera and other groups of Trechini, including epigean species of the same area. We compare the estimated age for the origin of the main groups resulting from two different calibrations, using one the standard mitochondrial mutation rate (2.3% divergence per Myr) and the other the separation between Sardinia and mainland 33 Ma. Under the first scenario, the main groups of genera would have a late Miocene origin, with a subsequent colonization of north Africa at the Pliocene–Pleistocene boundary. The assumption that the main groups originated through vicariance due to the separation of the Sardinian plate in the Oligocene results in a Messinian origin of the north African subterranean taxa, and a global mitochondrial rate reduced to 1% divergence per Myr.

Life-history specialization was not an evolutionary dead-end in Pyrenean cave beetles

“…We found clear geographical structuring within the Leptodirini, in agreement with previous results for the same group and for other subterranean organisms [11,14,15,31]. Even if within each of these geographically restricted lineages there were species known to have a modified life cycle, the required minimum number of independent transitions according to our phylogeny was surprisingly low.…”

X-ray microscopy reveals endophallic structures in a new species of the ground beetle genus Trechus Clairville, 1806 from Baltic amber (Coleoptera, Carabidae, Trechini)

“…Both species were identified as representatives of Trechus sensu auctorum which, based on molecular data, is a non-monophyletic assemblage (see Faille et al 2010, 2011, 2013). Due to the absence of male genital characters (the type of Trechus balticus is a female; the type of Trechus eoanophthalmus is a male but insufficiently preserved) it was argued that the taxonomic position of both fossil species within Trechus sensu lato cannot be assessed with certainty (Schmidt and Faille 2015, Schmidt et al 2016).…”

Climate change and its impact on epigean and hypogean carabid beetles

“…In the genus Abax the appearance of some allopatric species (e. g.: continuus and parallelus) can be explained only in terms of ice age climate dynamics (25). A strong evidence for post-Pliocene species divergence has given also for west-Mediterranean troglobitic Trechines studied by Faille et al (26), or alpine Trechine clades in the Plio-Pleistocene period (Faille et al, 27).…”

“…This highly dynamic picture relates to a temperature lowering of 8-10°C, as mostly assumed for the late glacial conditions of Eurasia or Northern America, and corroborated, at least in a first moment, Coope's idea of a marked evolutionary stability of the species involved. Recent population genetics research on short winged or apterous forms of carabids living in the alpine belt of North America (1), or bound to the more stable habitats of central and southern European mountains (23,26,27), demonstrates that a part of actual taxa are the result of late Pliocene or Quaternary splittings. This idea was in fact normally accepted by botanists and zoologists working on the Alps and in the Mediterranean countries.…”