Biology subjects

Barden, P.

Publications and source records attributed to Barden, P..

4 recordsLinked to original sources

bioRxiv2022

The first fossil replete ant worker establishes living food storage in the Eocene

Worker specialization extends the behavioral and ecological repertoire of ant colonies. Specialization may relate to colony defense, brood care, foraging, and, in some taxa, storage. Replete workers swell the crop and gaster to store liquid food, which can be accessed by other colony members through trophallaxis. This storage ability, known as repletism, has independently evolved across several ant lineages, but the temporal history of this trait has not yet been investigated. Here, we describe the first fossil replete in the extinct species Leptomyrmex neotropicus Baroni Urbani, 1980 preserved in Miocene-age Dominican amber. Together with new evidence of repletism in L. neotropicus extant sister species, L. relictus Boudinot et al., 2016, we reconstruct the pattern of acquisition and descent in this storage-linked trait. Our ancestral state reconstruction suggests that Leptomyrmex acquired replete workers in the Eocene and may therefore represent the earliest instance of so-called "honeypot" ants among all known ants, both living and extinct.

evolutionary biology↗

bioRxiv2022

Trait-based paleontological niche prediction demonstrates deep time parallel ecological occupation in specialized ant predators

Understanding the paleoecology of species is fundamental to reconstructions of paleoecological communities, analyses of changing paleoenvironments, and the evolutionary history of many lineages. One method of establishing paleoecology is through comparing the morphology of extant analogs to extinct species; this method has been applied to many vertebrate groups using predictive linear models, but has been rarely applied using invertebrate taxa or non-linear frameworks. The ant fossil record, which frequently preserves specimens in three-dimensional fidelity, chronicles putative faunal turnover during the Late Cretaceous and into Cenozoic. The earliest fossil species comprise enigmatic stem-groups that underwent extinction concomitant with crown ant diversification. Here, we apply a wide-ranging extant ecomorphological dataset to demonstrate the utility of Random Forest machine learning classification in predicting the ecology of stem-group "hell ants". We reconstruct a predicted ecomorphological assemblage of this phenotypically aberrant group of extinct ants, and compare predicted hell ant ecologies to the ecological occupations of their closest living analogs, lineages of solitary predators with highly specialized mandibular morphology. In contrast to previous hypotheses, we find that hell ants were primarily leaf litter or ground-nesting and foraging taxa, and that the ecological breadth of this unusual lineage mirrored that of living groups. Results suggest ecological coherence between the Mesozoic and modern communities, even as the earliest occupants of predatory niches were phylogenetically and morphologically distinct.

ecology↗

bioRxiv2022

Evolution and systematics of the Aculeata and kin (Hymenoptera),with emphasis on the ants (Formicoidea: {dagger}@@@idae fam. nov., Formicidae).

Fossils provide unique opportunity to understand the tempo and mode of evolution and are essential for modeling the history of lineage diversification. Here, we interrogate the Mesozoic fossil record of the Aculeata, with emphasis on the ants (Formicidae), and conduct an extended series of ancestral state estimation exercises on distributions of tip-dated combined-evidence phylogenies. We developed and illustrated from ground-up a series of 576 morphological characters which we scored for 144 extant and 431 fossil taxa, including all families of Aculeata, Trigonaloidea, Evanioidea, and {dagger}Ephialtitoidea. We used average posterior probability support to guide composition of a target matrix of 303 taxa, for which we integrated strongly filtered ultraconserved element (UCE) data for 115 living species. We also implemented reversible jump MCMC (rjMCMC) and hidden state methods to model complex behavioral characters to test hypotheses about the pathway to obligate eusociality. In addition to revising the higher classification of all sampled groups to family or subfamily level using estimated character polarities to diagnose nodes across the phylogeny, we find that the mid-Cretaceous genera {dagger}Camelomecia and {dagger}Camelosphecia form a clade which is robustly supported as sister to all living and fossil Formicidae. For this reason, we name this extinct clade as {dagger}@@@idae fam. nov. and provide a definition for the expanded Formicoidea. Based on our results, we recognize three major phases in the early evolution of the ants: (1) origin of Formicoidea as ground-adapted huntresses during the Late Jurassic in the "stinging aggressor" guild (Aculeata) among various lineages of "sneaking parasitoids" (non-aculeate Vespina); (2) the first formicoid radiation during the Early Cretaceous, by the end of which all major extant linages originated; and (3) turnover of the Formicoidea at the end-Cretaceous leading to the second formicoid radiation. We conclude with a concentrated series of considerations for future directions of study with this dataset and beyond.

evolutionary biology↗

bioRxiv2019

Fossil amber reveals springtails’ longstanding dispersal by social insects

Dispersal is essential for terrestrial organisms living in disjunct habitats and constitutes a significant challenge for the evolution of wingless taxa. Springtails (Collembola), the sister-group of all insects (with dipluran), are reported since the Lower Devonian and thought to have originally been subterranean. The order Symphypleona is reported since the early Cretaceous with genera distributed on every continent, implying an ability to disperse over oceans although never reported in marine water contrary to other springtail orders. Despite being highly widespread, modern springtails are generally rarely reported in any kind of biotic association. Interestingly, the fossil record has provided occasional occurrences of Symphypleona attached by the antennae onto the bodies of larger arthropods. Here, we document the case of a ~16 Ma old fossil association: a winged termite and ant displaying not some, but 25 springtails attached or closely connected to the body. The collembola exhibit rare features for fossils, reflecting their courtship and phoretic behaviors. By observing the modes of attachment of springtails on different arthropods, the sex representation and ratios in springtail antennal anatomies in new and previously reported cases, we infer a likely mechanism for dispersal in Symphypleona. By revealing hidden evidence of modern springtail associations with other invertebrates such as ants and termites, new compelling assemblages of fossil springtails and the drastic increase of eusocial insects’ abundance over Cenozoic (ants/termites comprising more than the third of insects in Miocene amber), we stress that attachment with winged casts of ants and termites may have been a mechanism for the worldwide dispersal of this significant springtail lineage. Moreover, by comparing the general constraints applying to the other wingless soil-dwelling arthropods known to disperse through phoresy, we suggest biases in the collection and observation of phoretic Symphypleona related to their reflexive detachment and infer that this behavior continues today. The specific case of tree resin entrapment represents the (so far) only condition uncovering the actual dispersal mechanism of springtails - one of the oldest terrestrial arthropod lineages living today. Associations with soil-dwelling social insects over time would have been at the origin of this behavioural specialization.View Full Text

paleontology↗