Many hexapod groups originated earlier and withstood extinction events better than previously realized: inferences from supertrees

Abstract

Comprising over half of all described species, the hexapods are central to understanding the evolution of global biodiversity. Direct fossil evidence suggests that new hexapod orders continued to originate from the Jurassic onwards, and diversity is presently higher than ever. Previous studies also suggest that several shifts in net diversification rate have occurred at higher taxonomic levels. However, their inferred timing is phylogeny dependent. We re-examine these issues using the supertree approach to provide, to our knowledge, the first composite estimates of hexapod order-level phylogeny. The Purvis matrix representation with parsimony method provides the most optimal supertree, but alternative methods are considered. Inferring ghost ranges shows richness of terminal lineages in the order-level phylogeny to peak just before the end-Permian extinction, rather than the present day, indicating that at least 11 more lineages survived this extinction than implied by fossils alone. The major upshift in diversification is associated with the origin of wings/wing folding and for the first time, to our knowledge, significant downshifts are shown associated with the origin of species-poor taxa (e.g. Neuropterida, Zoraptera). Polyneopteran phylogeny, especially the position of Zoraptera, remains important resolve because this influences findings regarding shifts in diversification. Our study shows how combining fossil with phylogenetic information can improve macroevolutionary inferences.

The fossil record and macroevolutionary history of the beetles

“…Indeed, 38 beetle families (approx.18%) have their first occurrences as inclusions within amber deposits. While biases in the record do exist, the ability to capture such a high percentage of extant beetle groups in the fossil record suggests that future studies which use phylogenetic approaches to study beetle biodiversity, would indeed benefit from the inclusion of fossil occurrences [6].…”

“…The role of the beetle fossil record to understand their historical patterns of diversification has been reduced to merely supplying a handful of calibration points for these analyses. This relatively insignificant role of the fossil record may be due, in part, to a general misperception that insects do not have a high potential for preservation [6], or that it is biased by exceptional deposits [7] (e.g. ambers), and otherwise is hopelessly incomplete (e.g.…”

Evidence for an Earliest Late Carboniferous Divergence Time and the Early Larval Ecology and Diversification of Major Holometabola Lineages

“…2), based on characters and taxonomic assignments from the respective descriptions. Accordingly, the earliest occurrences of many holometabolous clades had to be moved downward, earlier in time, to accommodate not only long-known Early Permian fossils, but also the four earlier holometabolous occurrences mentioned herein (also see Davis et al, 2010). The latter four taxa are reillustrated (Fig.…”

“…Under hemimetabolous development, an egg directly hatches into a series of discrete nymphal stages that largely resemble and give rise to the adult stage, which also can be compared to the ametabolous condition characterized by minimal developmental change. Insects with holometabolous development currently are the most diverse clade of multicellular organisms, consisting of approximately 766,100 described living species (Davis et al, 2010), although the total number is probably a several-fold multiple of that figure (Kristensen, 1999). The Holometabola presently constitute about 82.7 percent of all insects, and probably have been the dominant clade of insects since the mid Triassic.…”

The earliest earwigs in amber (Dermaptera): A new genus and species from the Early Cretaceous of Lebanon

“…Nonetheless, the order is morphologically and biologically diverse, and challenging to place among lower Neoptera (e.g., Grimaldi & Engel 2005 ;Davis et al 2010 ). Earwigs are moderately ancient, with relatively typical-looking species as old as the Late Jurassic, and putative records of earlier forms from as long ago as the Late Triassic (e.g., Jarzembowski 1999 ;Wappler et al 2005 ).…”