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

Abstract

Neoteny, the maintenance of larval features in sexually mature adults, is a radical way of generating evolutionary novelty through shifts in relative timing of developmental programmes. While controlled by the environment in facultative neotenics, retention of larval features is obligatory in many species of Lycidae (net-winged beetles). They are studied here as an example of how developmental shifts and ecology interact to produce macroevolutionary impacts. We conducted a phylogenetic analysis of Lycidae based on DNA sequences from nuclear (18S and 28S rRNA) and mitochondrial (rrnL, cox1, cob and nad5) genes from a representative set of lineages (73 species), including 17 neotenic taxa. Major changes of basal relationships compared with those implied in the current classification generally supported three independent origins of neotenics in Lycidae. The southeast Asian Lyropaeinae and Ateliinae were in basal positions indicating evolutionary antiquity, also confirmed by molecular clock estimates, unlike the neotropical leptolycines nested within Calopterini and presumably much younger. neotenics exhibit typical K-selected traits including slow development, large body size, high investment in offspring and low dispersal. This correlated with low species richness and restricted ranges of neotenic lineages compared with their sisters. Yet, these factors did not impede the evolutionary persistence of affected lineages, even without reversals to fully metamorphosed forms, contradicting earlier suggestions of recent evolution from dispersive non-neotenics.

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

“…Convergences in these traits have to be seen in the context of miniaturization of males, i.e. sexually linked body size differentiation [34,35] and hypothesized to be a result of the K-and r-strategy of the respective sexes [4]. Miniaturization is linked to the absence of the pronotal carinae and elytral costae as strengthening structures.…”

“…Thus, the Iberobaeniidae may represent another example of an ancient neotenic lineage, despite being species-poor. Equally, various neotenic lineages of Lycidae and Omalisidae exhibit high endemism and relict occurrence [4,36], as found in Iberobaeniidae. Neotenic females are apterous and short-lived during the adult stage, and thus due to their limited dispersal, population persistence is predicted to require geological and climatic stability [35,39].…”

“…R. Soc. B 283: 20152350 are placed deeply in the tree and have undergone diversification, albeit at a low rate [4]. Thus, the Iberobaeniidae may represent another example of an ancient neotenic lineage, despite being species-poor.…”

“…These groups, with few exceptions, exhibit females that are neotenic (retaining juvenile traits) to various degrees, and are either completely larviform, show a metamorphosed head but with the rest of the body larviform, or retain larval traits only in the abdomen. Soft-bodiedness and loosely connected abdominal sclerites resembling larval morphology possibly represent an initial stage of ontogenetic modifications [4]. Owing to the morphological similarities, families with these characteristics were traditionally grouped into a separate superfamily of soft-bodied lineages, the Cantharoidea ( [5]; figure 1b) or as a monophylum within Elateroidea [7].…”

Phylogeography of Poorly Dispersing Net-Winged Beetles: A Role of Drifting India in the Origin of Afrotropical and Oriental Fauna

“…Further, lineages with an uninterrupted long-term diversification are preferable to avoid confounding impacts of extinctions. The metriorrhynchine beetles are a highly diverse Palaeotropical lineage with ∼1400 species and their origin was hypothesized in the Late Cretaceous [10], [11]. Low dispersal ability of net-winged beetles is due to strong dependence on rain forest habitats, weak short-distance flight, short adult life span, and the presence of geographically limited aposematic patterns [12], [13].…”