Literature Review: Arthropod Evolution

by Carl Strang

If you’re a bug nerd you’ll enjoy the following notes on research from 2013. Especially significant were studies of butterflies and moths, and an eye-opening paper on periodical cicadas. This concludes my literature review until next winter.

Butterflies and moths had their origin in the Triassic Period according to recent studies, though the first ones were more like caddis flies than like this red-spotted purple.

Butterflies and moths had their origin in the Triassic Period according to recent studies, though the first ones were more like caddis flies than like this red-spotted purple.

Zhang, W, et al. 2013. New fossil Lepidoptera (Insecta: Amphiesmenoptera) from the Middle Jurassic Jiulongshan Formation of northeastern China. PLoS ONE 8(11): e79500. doi:10.1371/journal.pone.0079500  They found 15 species of early moths representing at least 3 families in Chinese deposits, and details of wing venation led to the conclusion that the Lepidoptera (moths and butterflies) diverged from the Trichoptera (caddis flies) by the early Jurassic Period.

Wahlberg, N, CW Wheat, C Peña 2013. Timing and patterns in the taxonomic diversification of Lepidoptera (butterflies and moths). PLoS ONE 8(11): e80875. doi:10.1371/journal.pone.0080875  They estimated timings of major episodes of speciation in the major groups of butterflies and moths. Their results point to a Triassic origin of Lepidoptera, around 215 million years ago. The timing of diversification episodes at least in some cases corresponds to times when plants were diversifying, and also after the end-Cretaceous mass extinction. Coevolution of lepidoptera with their larval food plants appears to be an important theme. They give origin ages for major Lepidoptera groups (in millions of years ago): Gracillarioidea 120, Yponomeutoidea 117, Glechioidea 106 (these first three are small moths, many of them leaf miners), Papilionoidea 104 (butterflies), Pyraloidea (including many local pyralid moths) 93, Bombycoidea (including sphinx moths) 84, Geometroidea (including inchworm moths) 83, Noctuoidea (the enormous owlet moth group) 82, Tortricoidea (including leaf-folding caterpillars) 68. All these groups are represented by local species.

The Chicago region’s 17-year periodical cicadas: Magicicada septendecim, left, and M. cassini.

The Chicago region’s 17-year periodical cicadas: Magicicada septendecim, left, and M. cassini.

Sota, Teiji, Satoshi Yamamoto, John R. Cooley, Kathy B.R. Hill, Chris Simon, and Jin Yoshimura. 2013. Independent divergence of 13- and 17-y life cycles among three periodical cicada lineages. Proc. Nat. Acad. Sci. 110:6919-6924. They sequenced a number of genes from nuclear and mitochondrial DNA from all known species and broods, and estimated divergence times based on general research that has been done on insect mitochondria. There are three species groups (referred to as Decim, Cassini, and Decula), each of which contains northern 17-year species and southern 13-year species. In any location, the species in the different groups emerge at the same time. The results clearly separated the three groups, and tied together the species within each group (e.g., 13-year Decim are more closely related to 17-year Decim than to 13-year Cassini). Furthermore, each species group is divided into eastern, central and western genetic clusters (this pattern has been documented in other organisms as well; for the most part, Illinois cicadas are in western clusters, Indiana ones in central clusters). Each cluster contains both 13- and 17-year species, “suggesting that life cycle divergence occurred independently in the three regions.” Analyses estimated that the western Cassini divergence of 13-year and 17-year species took place 23,000 years ago, 10,000 years for Decim. Population sizes for both Decim and Cassini groups appear to have been small during the last glacial period, but expanded greatly starting 10,000 years ago. The sequence appears to have been allopatric speciation of the 3 ancestral species, with the species later becoming sympatric and independently splitting into 13- and 17-year cicadas. “Surprisingly, however, the divergence of 13- and 17-y cicadas was asynchronous among the species groups and occurred repeatedly even within a species group.” The implication is “that the three Magicicada groups shared multiple refugia during the last glacial maximum.” The 13-/17-year splits occurred after the last glacial maximum, within the last 23,000 years, “suggesting that the life cycle divergence in Magicicada is closely associated with global climatic fluctuations and shorter growing seasons in the north versus the south.” However, the species groups themselves separated in the Pliocene, and their shared long lives suggest that this did not originate because of glacial climate influences. This shifting between 13- and 17-year life cycles suggests a common genetic basis among the species, and indicates a somewhat plastic nature of this trait. The coordination among species at a given location seems best explained by the selective advantage of low numbers of an invading species into the range of another, surviving best when sheltered by the established species’ numbers.

Zhao, Z, et al. 2013. The mitochondrial genome of Elodia flavipalpis Aldrich (Diptera: Tachinidae) and the evolutionary timescale of tachinid flies. PLoS ONE 8(4): e61814. doi:10.1371/journal.pone.0061814  Their genomic study traced the evolutionary relationships of the parasitic fly family Tachinidae, and molecular clock analysis calibrated to the fossil record points to the middle Eocene as the time of the family’s origin.

Brewer, MS, and JE Bond. 2013. Ordinal-level phylogenomics of the arthropod class Diplopoda (millipedes) based on an analysis of 221 nuclear protein-coding loci generated using next-generation sequence analyses. PLoS ONE 8(11): e79935. doi:10.1371/journal.pone.0079935  They place the ancestral millipedes at 510mya (million years ago), with major groupings established by 200mya.

Lucky, A, MD Trautwein, BS Guénard, MD Weiser, RR Dunn. 2013. Tracing the rise of ants – out of the ground. PLoS ONE 8(12): e84012. doi:10.1371/journal.pone.0084012     A phylogenetic analysis points to soil rather than leaf litter as the nesting habitat for the earliest ant species.

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Prehistoric Life 9

by Carl Strang

This year’s winter series is a review of the prehistoric life and geologic history of northeast Illinois. Each chapter will summarize current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert.

Pennsylvanian Period (320-286 million years ago)

The Pennsylvanian Period is named for the state of Pennsylvania (1891). This North American subdivision of the European Carboniferous Period is distinguished by many cyclic repeated advances and retreats of the sea, as indicated by alternating rock layers.

Life on Earth. This was the time of the coal forests, when the growing land area provided the home for forests of lycopsids (club mosses, the most abundant trees), sphenopsids (the group containing today’s scouring rush, horsetails and other members of genus Equisetum), ferns (including tree ferns), and seed ferns. There were early conifers as well. These were vascular but not flowering plants. Most coal was produced during this period because fungi, critical to decomposition, had not yet developed that ability to a significant extent. Dead plant tissue piled up without breaking down, ultimately was buried and fossilized into coal. As a result, oxygen built in the atmosphere to an all time high of 30% (Science 316:557).

You can see a life-sized reconstruction of a Pennsylvanian forest at the Field Museum in Chicago. Here are some model sphenopsids.

The earliest Amniota (the terrestrial egg-bearing group ultimately including reptiles, birds and mammals) appeared and diverged in the Pennsylvanian, producing the cotylosaurs (and other anapsid reptiles, a group represented by turtles and tortoises today; fossil cotylosaurs have been found as close to Illinois as Nova Scotia), synapsids (also known from N.S. and the group from which mammals ultimately evolved; the basal synapsids are referred to as pelycosaurs), and the diapsids, a reptile group that evolved into lizards, snakes, dinosaurs, birds and crocodiles.

Winged insects (including the first mayflies and enormous primitive dragonflies) first appeared in the Pennsylvanian, as did cockroaches, grasshoppers and crickets. The earliest beetle was reported from Illinois fossil material in 2009 (J. Paleont. 83:931). Some invertebrates, such as the dragonflies and certain millipedes, reached giant sizes (thanks at least in part to the elevated oxygen levels).

Local landscape. In Illinois, the sea continued its advance and retreat cycling, so that our area alternated between marine and land, often low and swampy. Our area remained just south of the equator, and the climate was warm and humid.  It is thought that alternating periods of glaciers forming and thawing on the southern Gondwana supercontinent (at that time drifting over the South Pole) caused the rises and falls of sea level that produced the local advances and retreats of the sea. Over geologic time, glacial episodes typically are associated with a continental mass at one of the poles (Antarctica in recent times).

Tree ferns still exist today. This one in Tasmania had a thick stem more than 10 feet tall.

The North American continent was beginning to collide with Europe and Africa as the sea that had begun to appear between them closed, forming the northern supercontinent of Laurasia. This event is what lifted our part of the world above the sea for good.

The nearest Pennsylvanian bedrock to Chicago is the Mazon Creek area (much of Illinois’ bedrock is Pennsylvanian), except for some bits in the Des Plaines Disturbance.

Local life. Coal forests dominated Illinois during the Pennsylvanian. Not only was coal left (itself fossil plant material), but remains of a variety of plant and animal fossils can be found just a little south of us in the world-famous Mazon Creek deposits of Middle Pennsylvanian age, just a little southwest of Joliet. Seed-fern leaves such as Medullosa, Neuropteris inflata, N. scheuchzeri, N. ovata and N. rarinerus are especially abundant (note: names of these plants are confusing, because different names are given to different parts such as leaves, stems and reproductive parts). There also were the giant sphenopsid Calamites, the smaller weedy horsetail Sphenophyllum, the tree fern Psaronius, small ferns (Pecopteris, Sphenopteris, Alloiopteris), the conifer relative Cordaites, giant club moss relatives Cyperites, Lepidodendron, Lepidophloios, and Sigillaria (up to 6 feet in diameter!), and other, smaller club mosses (Lycopodites, Bothrodendron).

Here are some giant club mosses in the Field Museum exhibit.

Most bizarre among the diverse aquatic animals was the Tully monster (Tullimonstrum gregarium), first found by amateur fossil collector Francis Tully, Illinois’ state fossil, and only known from this area. There were horseshoe crabs (Palaeolimulus, Euproops), freshwater fish (Rhabdoderma oxiguum, Conchopoma edesi, Elonichthyes peltigerus, Platysomus circularis), and mollusks, as well as a lamprey-like fish, Actinopterygian fishes (Elonichthys pettigerus, Platysomus circularis), polychaete worms (Astreptoscolex anasillosus, Escorites zelus, and others), shrimps (Belotelson sp., Kallidecthes richardsoni, Acanthotelson stimsoni, and others), a sea cucumber (Achistrum sp.), a nematode (Nemavermes mackeei), a chiton (Glaphurochiton concinnus), ribbon or priapulid worms (Archisymplectes rhothon, Priapulites konecniorum), the arrow worm Paucijaculum samamithion, the spoonworm (phylum Echiura) Coprinoscolex ellogimus, jellyfish (Essexella asherae, Octomedusa pieckorum, Anthracomedusa turnbullii), cephalopods, brachiopods (Lingula sp.), the scallop Aviculopectin mazonensis, as well as several “mystery animals” of unknown affinities. 

The Field Museum model forest includes a millipede you could put a saddle on!

Land animals included centipedes, millipedes (the giant millipede Arthropleura cristata was a flat species, 16” wide and more than 6 feet long), scorpions, cockroaches (Platymylacris paucineruis) and their relatives (Gerarus danielsi, G. vetus), and spider-like arachnids. There were amphibians (Amphibamus grandiceps, A. yelli).

The upland trees, less well known, were different from those in the swamps, and included the genera Megalopteris and Lesleya. An upland animal was the scorpion Labriscorpio alliedensis.

Prehistoric Life 7

by Carl Strang

This year’s winter series is a review of the prehistoric life and geologic history of northeast Illinois. Each chapter will summarize current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert.

Devonian Period (408-360 million years ago)

The Devonian Period was named in 1837 for Devonshire, where fossils were first found intermediate between those of Silurian and Carboniferous periods. Its beginning formally is defined by the first appearance of the graptolite Monograptus uniformis. For DuPage County, with a single exception, the geological deposits end with the Silurian, and do not resume until the relative eyeblink of the past 12,000 years.

Life on Earth. In some ways the Devonian period continued much as the Silurian had, with reefs and their associated life forms continuing to develop and diversify. Petoskey stone, the Michigan state rock, is a middle Devonian massive colonial tabulate coral, Hexagonaria percarinata. Brachiopods remained diverse in the Devonian, but then began their decline. Trilobites remained diverse. Crabs were a new marine arthropod group in the Devonian. A significant new group of cephalopod mollusks, the ammonites, appeared. There was a massive extinction of marine forms in the late Devonian, marking the beginning of a long period where there were no large reefs until the mid-Triassic. This mass extinction coincided with a big drop in atmospheric oxygen (Science 316:557).

Today’s bluegill are members of Osteichthyes, the first of which appeared in the Devonian.

Fishes diversified, and the Devonian has been described as the “Age of Fishes.” There were 4 groups of jawed fishes: placoderms (armored; almost entirely limited to the Devonian), acanthodians (“spiny sharks,” some of which were abundant, small school-forming fishes), Chondrichthyes, and Osteichthyes. The latter two groups, which dominate today’s fishes, both first appeared in the Devonian, including both the lobe-finned (coelacanth, lungfish) and ray-finned branches of Osteichthyes, and the first true sharks (Chondrichthyes). Lampreys likewise first showed in the Devonian fossil record. These fishes were diverse ecologically as well, with plankton feeders, bottom feeders, and mobile predators.

In 2006 paleontologists described a fossil lobe-finned fish from northern Canada, 375 million years old, that is the most clearly intermediate example to date between fish and terrestrial vertebrates. Tiktaalik roseae had “fins better engineered for standing than swimming.” Also, it had lost gill cover plates, and possessed a shoulder girdle largely separated from the skull (i.e., the fish had a neck). They probably were both poor crawlers and poor swimmers, but in their river delta environment they could escape aquatic predators (Science 312:33).

The diversification of fishes and sharks as well as shell-crushing arthropods in the “Middle Paleozoic Marine Revolution” of the Silurian and Devonian Periods had a measurable impact on some of their prey (Science 305:1453). Crinoid arm regeneration increased and antipredator morphologies became more common as this time passed. Crinoids “developed more spines, thicker calyx plates, and reduced viscera.” Regenerating crinoid arms in fossils increased from less than 5% in the Ordovician and Silurian to more than 10% in the Devonian to Pennsylvanian. Close study of another group of marine invertebrates, rugose corals, has shown that the Earth was spinning faster then, so that days were 21 hours long.

Land plants were similar all over the world, implying a uniform warm climate. Early vascular land plants were small, and mainly consisted of branching stems with spore producing structures. True leaves appeared in the Devonian. The first forests emerged by the late Devonian, the trees belonging to groups called progymnosperms and seed ferns. The seeds contain spores, and the leaves are fernlike fronds. They were the ancestors of more modern plants that appeared in the Mesozoic, the cycads and flowering plants or angiosperms. There were also giant club mosses, and the first true ferns. The Devonian also produced the first lichens.

Terrestrial invertebrates diversified, producing the first millipedes, centipedes, pseudoscorpions, spiders, harvestmen (daddy long-legs), mites, and insects (springtails being a group that has persisted to the present day).

The first, labyrinthodont, amphibians appeared in the late Devonian. At least some did come out on land, and were predators. They were sufficiently widespread that they occurred in both Greenland and Australia, which even then were well separated.

Local landscape. In the early Devonian, our area is thought to have become low land as the sea retreated, the result of crustal warping, and still was a little south of the equator. The area subsided later in the period to become a shallow sea in which limestone again was deposited. The second phase of the Appalachian mountain building occurred with the Acadian orogeny in the late Devonian, as continental plates collided to the east. Then, muds eroding from uplifted lands to the east produced the Devonian New Albany shale that forms the bed of Lake Michigan. Some of that shale was gouged out, ground up, transported and deposited by the latest continental glacier to form DuPage County’s clay soil. The nearest Devonian bedrock therefore is just east of our area. However, cracks in the upper surface of the Silurian dolomite in an Elmhurst quarry contained clay that was deposited during the Devonian (or, possibly, Mississippian).

Local life. The mud-bottomed sea was contiguous in the late Devonian from here to northern Iowa, where there were forms ranging from a lobe-finned lungfish to an ammonite along with various stromatoporoids, corals, clams, snails, brachiopods and bryozoans. Horn corals and tabulate forms were diverse and abundant.

This enormous arthrodire fossil can be seen at the Field Museum.

The fierce looking arthrodires, the most diverse placoderms, were widely distributed across North America in the middle and late Devonian. The shark-like Cladoselache, of the Chondrichthyes, is known from Ohio. Falls of the Ohio State Park at Jeffersonville, Indiana, also has middle Devonian fossiliferous limestone and shale deposits. The limestone has more than 600 species of corals, sponges, brachiopods, mollusks, echinoderms, and others.

The Devonian or Mississippian clay found in Elmhurst actually contained some fossil shark teeth. Central Illinois Devonian fossils include the branching coral Alveolites, tabulate corals Hexagonaria and Pachyphyllum, the horn coral Zaphrentis, brachiopods Schizophoria, Douvillina, Cyrtina, Atrypa, Spinocyrtia, Schuchertella, and Strophodonta, and trilobites Odontocephalus and Phacops.

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