Molecular phylogenetics of Elateriformia (Coleoptera): evolution of bioluminescence and neoteny

Abstract

Phylogenetic relationships in the coleopteran Series Elateriformia (click beetles, jewel beetles, fireflies and allies) were investigated using > 3800 nucleotides of partial nuclear (small and large subunit rRNA genes) and mitochondrial (large subunit rRNA and cytochrome oxidase subunit I) gene sequences. The Elateriformia includes several soft-bodied lineages, some of which retain larviform features in the adult stage (neoteny), and several major bioluminescent groups, including the families Lampyridae (fireflies), Phengodidae and Rhagophthalmidae whose relationships have been contentious. All recognized superfamilies (Elateroidea, Cantharoidea, Byrrhoidea, Buprestoidea, Dascilloidea, Scirtoidea) and 28 of the 37 families, represented in 112 individuals, were included in the analysis. Sequence alignment was based on static and dynamic homology assignments and partial removal of sequences of uncertain homology. Alignment variable regions caused a great deal of uncertainty but also contributed much of the phylogenetic signal that was insufficient to resolve deep relationships when these were removed. The main features of most analyses were the monophyly of Elateroidea + Cantharoidea (¼ Elateroidea sensu lato), with Omethidae + Telegeusidae frequently occupying the basal node in this group; the affinities of Dascilloidea, Buprestoidea and a (broadly paraphyletic) Byrrhoidea, with unclear relationships among them; and the monophyly of Scirtoidea (including Decliniidae) as a rather distant outgroup to all others. When mapped on the resulting trees, soft-bodied lineages were polyphyletic, contradicting the former Cantharoidea that had been united by this trait. Transitions to neoteny were either simultaneous with, or subsequent to, the origin of soft-bodiedness in a minimum of seven lineages. The bioluminescent groups Lampyridae (including the enigmatic genus Drilaster) and the tightly allied Phengodidae + Rhagophthalmidae were never monophyletic. The former showed close relationship to the species-rich, soft-bodied families Lycidae and Cantharidae, while the latter grouped with poorly resolved lineages at the base of Elateridae (click beetles). Hence, although key features as soft-bodiedness, neoteny and bioluminescence in Coleoptera are largely confined to the Elateriformia, they appear to result from multiple origins, showing the propensity of closely related lineages to acquire similar features independently.

The discovery of Iberobaeniidae (Coleoptera: Elateroidea): a new family of beetles from Spain, with immatures detected by environmental DNA sequencing

“…Lissominae has a tendency to group with Lycidae [25], and close relatives of Mastinocerus (e.g. Rhagophthalmus) were never found with Lycidae in all previous analyses [8,13,25]. No morphological character of Lissominae or Mastinocerus supports a close relationship to Lycidae and Iberobaenia.…”

Multiple ancient origins of neoteny in Lycidae (Coleoptera): consequences for ecology and macroevolution

“…The origin of these strategies for predator evasion clearly preceded the shift to extreme neoteny. Together with slow locomotion and soft-bodiedness (which may in fact constitute a basic form of neoteny; Bocakova et al 2007), their highly efficient defence mechanism may have provided the evolutionary settings where neoteny became advantageous. It is unlikely that the cause-effect relationship is reversed, i.e.…”

Taxonomy of the Brazilian firefly Cladodes illigeri (Coleoptera, Lampyridae): morphology and new records

“…The type genus Vesta Laporte, 1833 has south-east Asiatic and south-American distribution, whilst other genera of the subtribe (Cladodes, Ledocas Olivier, 1885, Dodacles Olivier, 1885, and Dryptelytra Laporte, 1833 are exclusively Neotropical. While Asiatic fireflies have recently been studied (Sagegami-Oba et al, 2007;Bocakova et al, 2007), phylogenetic relationships of South-American fireflies are still ambiguous, both at the generic and the species level. This is also true for Cladodes, where the majority of the species is known only from the type specimens.…”