Analysis of anchored hybrid enrichment (AHE) data under a variety of analytical parameters for a broadly representative sample of taxa (136 species representing all extant families) recovered a well-resolved and strongly supported tree for the higher phylogeny of Neuropterida that is highly concordant with previous estimates based on DNA sequence data. Important conclusions include: Megaloptera is sister to Neuroptera; Coniopterygidae is sister to all other lacewings; Osmylidae, Nevrorthidae and Sisyridae are recovered as a monophyletic Osmyloidea, and Rhachiberothidae and Berothidae were recovered within a paraphyletic Mantispidae. Contrary to previous studies, Chrysopidae and Hemerobiidae were not recovered as sister families and morphological similarities between larvae of both families supporting this assumption are reinterpreted as symplesiomorphies. Relationships among myrmeleontoid families are similar to recent studies except Ithonidae are placed as sister to Nymphidae. Notably, Ascalaphidae render Myrmeleontidae paraphyletic, again calling into question the status of Ascalaphidae as a separate family. Using statistical binning of partitioned loci based on a branch-length proxy, we found that the diversity of phylogenetic signal across partitions was minimal from the slowest to the fastest evolving loci and varied little over time. Ancestral character-state reconstruction of the sclerotization of the gular region in the larval head found that although it is present in Coleoptera, Raphidioptera and Megaloptera, it is lost early in lacewing evolution and then regained twice as a nonhomologous gula-like sclerite in distantly related clades. Reconstruction of the ancestral larval habitat also indicates that the ancestral neuropteridan larva was aquatic, regardless of the assumed condition (i.e., aquatic or terrestrial) of the outgroup (Coleopterida).
For nearly 100 million years, the India subcontinent drifted from Gondwana until its collision with Asia some 50 Ma, during which time the landmass presumably evolved a highly endemic biota. Recent excavations of rich outcrops of 50–52-million-year-old amber with diverse inclusions from the Cambay Shale of Gujarat, western India address this issue. Cambay amber occurs in lignitic and muddy sediments concentrated by near-shore chenier systems; its chemistry and the anatomy of associated fossil wood indicates a definitive source of Dipterocarpaceae. The amber is very partially polymerized and readily dissolves in organic solvents, thus allowing extraction of whole insects whose cuticle retains microscopic fidelity. Fourteen orders and more than 55 families and 100 species of arthropod inclusions have been discovered thus far, which have affinities to taxa from the Eocene of northern Europe, to the Recent of Australasia, and the Miocene to Recent of tropical America. Thus, India just prior to or immediately following contact shows little biological insularity. A significant diversity of eusocial insects are fossilized, including corbiculate bees, rhinotermitid termites, and modern subfamilies of ants (Formicidae), groups that apparently radiated during the contemporaneous Early Eocene Climatic Optimum or just prior to it during the Paleocene-Eocene Thermal Maximum. Cambay amber preserves a uniquely diverse and early biota of a modern-type of broad-leaf tropical forest, revealing 50 Ma of stasis and change in biological communities of the dipterocarp primary forests that dominate southeastern Asia today.
Insects are the most diverse lineage of all life in numbers of species, and ecologically they dominate terrestrial ecosystems. However, how and when this immense radiation of animals originated is unclear. Only a few fossils provide insight into the earliest stages of insect evolution, and among them are specimens in chert from Rhynie, Scotland's Old Red Sandstone (Pragian; about 396-407 million years ago), which is only slightly younger than formations harbouring the earliest terrestrial faunas. The most well-known animal from Rhynie is the springtail Rhyniella praecursor (Entognatha; Collembola), long considered to be the oldest hexapod. For true insects (Ectognatha), the oldest records are two apparent wingless insects from later in the Devonian period of North America. Here we show, however, that a fragmentary fossil from Rhynie, Rhyniognatha hirsti, is not only the earliest true insect but may be relatively derived within basal Ectognatha. In fact, Rhyniognatha has derived characters shared with winged insects, suggesting that the origin of wings may have been earlier than previously believed. Regardless, Rhyniognatha indicates that insects originated in the Silurian period and were members of some of the earliest terrestrial faunas.
The last 25 years of phylogenetic investigation into the three orders constituting the superorder Neuropterida-Raphidioptera, Megaloptera, and Neuroptera-have brought about a dramatic revision in our understanding of the evolution of lacewings, snakeflies, dobsonflies, and their diverse relatives. Phylogenetic estimations based on combined analyses of diverse data sources, ranging from adult and larval morphology to full mitochondrial genomic DNA, have begun to converge on similar patterns, many times in accordance with hypotheses put forth by Cyril Withycombe nearly a century ago. These data, in combination with information from the fossil record, have given a revised perspective on the historical evolution and classification of Neuropterida, necessitating an overhaul of their organization and providing focus and insight on fruitful future efforts for neuropterology.
The Eumetabola (Endopterygota (also known as Holometabola) plus Paraneoptera) have the highest number of species of any clade, and greatly contribute to animal species biodiversity. The palaeoecological circumstances that favoured their emergence and success remain an intriguing question. Recent molecular phylogenetic analyses have suggested a wide range of dates for the initial appearance of the Holometabola, from the Middle Devonian epoch (391 million years (Myr) ago) to the Late Pennsylvanian epoch (311 Myr ago), and Hemiptera (310 Myr ago). Palaeoenvironments greatly changed over these periods, with global cooling and increasing complexity of green forests. The Pennsylvanian-period crown-eumetabolan fossil record remains notably incomplete, particularly as several fossils have been erroneously considered to be stem Holometabola (Supplementary Information); the earliest definitive beetles are from the start of the Permian period. The emergence of the hymenopterids, sister group to other Holometabola, is dated between 350 and 309 Myr ago, incongruent with their current earliest record (Middle Triassic epoch). Here we describe five fossils--a Gzhelian-age stem coleopterid, a holometabolous larva of uncertain ordinal affinity, a stem hymenopterid, and early Hemiptera and Psocodea, all from the Moscovian age--and reveal a notable penecontemporaneous breadth of early eumetabolan insects. These discoveries are more congruent with current hypotheses of clade divergence. Eumetabola experienced episodes of diversification during the Bashkirian-Moscovian and the Kasimovian-Gzhelian ages. This cladogenetic activity is perhaps related to notable episodes of drying resulting from glaciations, leading to the eventual demise in Euramerica of coal-swamp ecosystems, evidenced by floral turnover during this interval. These ancient species were of very small size, living in the shadow of Palaeozoic-era 'giant' insects. Although these discoveries reveal unexpected Pennsylvanian eumetabolan diversity, the lineage radiated more successfully only after the mass extinctions at the end of the Permian period, giving rise to the familiar crown groups of their respective clades.
A hallmark of animals that are eusocial, or those with advanced sociality, is reproductive specialization into worker and queen castes. In the most derived societies, these divisions are essentially fixed and in some arthropods, include further specialization--a tripartite system with a soldier caste that defends the colony. Eusociality has originated numerous times among insects but is believed to have appeared first in the termites (Isoptera), in the Early Cretaceous. However, all termites known from the Cretaceous have, until now, only been winged reproductives (alates and dealates); the earliest soldiers and definitive workers were known from just the Miocene (ca. 17-20 million years ago [mya]). Here, we report six termite species preserved in Early Cretaceous (ca. 100 mya) amber from Myanmar, one described as Krishnatermes yoddha gen. et sp. nov., comprising the worker/pseudergate, winged reproductive, and soldier, and a second species, Gigantotermes rex gen. et sp. nov., based on one of the largest soldier termites yet known. Phylogenetic analysis indicates that Krishnatermes are in the basal "Meiatermes-grade" of Cretaceous termites. Workers/pseudergates of another four species are briefly described, but not named. One of these workers/pseudergates reveals that ants--the most serious enemies of modern termites--lived in close proximity to termites in the Burmese paleofauna. These discoveries demonstrate the Mesozoic antiquity of specialized termite caste systems and corroborate that among all social species, termites probably had the original societies.
A diverse insect assemblage of exceptionally preserved debris carriers is reported from Cretaceous Burmese, French, and Lebanese ambers.
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