The Wiegmann Lab

Dipteran Molecular Systematics at North Carolina State University

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- Matt Bertone -

Degree Program: Ph.D.

CV

Research Interests:

'Nematocera' Family Relationships

I am using molecular techniques to investigate the evolutionary relationships of lower/nematocerous flies, historically referred to as the Diptera suborder Nematocera. Nematocerous flies are considered the oldest group within the Diptera. This 'suborder' includes some familiar fly families [Culicidae (mosquitoes), Tipulidae (crane flies), Chironomidae (non-biting midges), Bibionidae (march flies), etc.] in addition to several small, enigmatic families [Nymphomyiidae, Axymyiidae, Deuterophlebiidae (mountain midges), etc.]. Many are economically important as disease vectors (mosquitoes, black flies, biting midges and sand flies) or crop pests (gall midges). Also included in this group is the family of flies with the most described species (Tipulidae; 15,000+ species). Ecologically diverse, the nematocerous Diptera occupy various habitats (fully aquatic, semi-aquatic, wood-boring, desert dwelling, etc.) and trophic levels (predators, herbivores, fungivores, detritivores and parasites).

Morphologically, nematocerous flies differ from their more derived relatives, the Brachycera, in several ways:

- as their name implies, nematocerous ("thread-horned") flies have long antennae composed of multiple antennomeres; Brachycera ("short-horn") usually have antennae composed of three, compact antennomeres

- all larvae of nematocerous flies have four instars; the number of instars in the larvae of Brachycera varies, but in most derived flies there are only 3 instars

- larvae of nematocerous flies usually have a well-developed head capsule (with mandibles that move on a horizontal plane); larvae of the Brachycera have a reduced/absent head capsule (with slender mandibles that move parallel to each other on a vertical plane)

Though these differences have traditionally been adaquate enough to merit sub-ordinal ranks for both a 'Nematocera' and a Brachycera, mounting phylogenetic evidence points toward a paraphyletic 'Nematocera' with Brachycera arising from one of its main lineages.

While the paraphyly of the 'Nematocera' is not a new nor highly contested idea, there are still many questions about this ancient group of flies. Previous hypotheses on the relationships among families (and infraorders) in this group have differed substantially. My research aims at answering some of the major questions about early dipteran evolution through gene sequence data. These questions include:

- Which extant lineage was the first to develop within the Diptera (presumably from a Mecoptera-like ancestor)?

- Which families are closely related?

- What infraorders can we group families into, and how are they related?

- From what group (infraorder) did the Brachycera radiate from?

- Are any traditional nematocerous families paraphyletic?

Tipulidae or Tipuloidea?

My other project involves inferring the higher-level relationships within the family Tipulidae sensu lato (s.l.). This large family (15,000+ species) contains the familiar crane flies: large, fragile insects that are often mistaken for mosquitoes. Crane flies are ecologically diverse, living as larvae in aquatic, semi-aquatic and terrestrial habitats. Larval crane flies are diverse in feeding habits (predators, detritivores and herbivores), while the adults are mainly non-feeding (some take nectar).

This family is often separated into 4 families (Pediciidae, Limoniidae, Cylidrotomidae and Tipulidae) known collectively as the superfamily Tipuloidea. The Pediciidae appear to be the most basal group among these flies, possessing the plesiomorphic character of setae between the ommatidia of their eyes. The Limoniidae is the largest of the four families, containing 11,000+ species. Limoniid diversity is extensive and the family has been divided into several poorly defined subfamilies, whose relationships are unclear. The Cylindrotomidae are represented by 70 + species, and are apparently closely related to the Tipulidae sensu stricto (s.s.). The Tipulidae s.s. are a large family of 4,000+ species. They are the most commonly encountered of the Tipuloidea, due to their large size.

Phylogenetically little is known about this group of flies. The taxonomy of this group is somewhat unclear, and the inter-realtionships among crane fly families and genera are almost wholly unknown. In a collaborative effort to remedy the current state of Tipuloid systematics, Matt Petersen (Ph.D. student, Iowa State University) and I are collecting both molecular and morphological data to determine (a) the status of these four 'families', (b) the status of the limoniid subfamilies, and (c) the relationships between genera of Tipuloidea.

LIST OF TRADITIONAL NEMATOCEROUS FLY FAMILIES

Anisopodidae (wood gnats) [sometimes divided into two families including Mycetobiidae and Anisopodidae s.s.]

Axymyiidae

Bibionidae (march flies) [sometimes divided into three families including Pleciidae, Hesperinidae and Bibionidae s.s.]

Blephariceridae (net-winged midges)

Cecidomyiidae (gall midges)

Ceratopogonidae (biting midges)

Corethrellidae [sometimes a subfamily of Chaoboridae]

Chaoboridae (phantom midges)

Chironomidae (non-biting midges)

Culicidae (mosquitoes)

Deuterophlebiidae (mountian midges)

Dixidae

Mycetophilidae (fungus gnats) [sometimes including Sciaridae or divided into several families including Bolitophilidae, Diadocidiidae, Ditomyiidae, Keroplatidae, Lygistorrhinidae and Mycetophilidae s.s.]

Nymphomyiidae

Pachyneuridae [sometimes divided into two families Cramptonomyidae and Pachyneuridae s.s.]

Perissommatidae

Psychodidae (moth & sand flies)

Ptychopteridae (phantom crane flies)

Scatopsidae (black scavenger flies)

Sciaridae (dark-winged fungus gnats) [sometimes a subfamily of the Mycetophilidae or divided into two families Rangomaramidae and Sciaridae s.s.]

Simuliidae (Black flies)

Canthyloscelidae (=Synneuridae)

Tanyderidae (primitive crane flies)

Tipulidae (crane flies) [sometimes divided into up to four families including Pediciidae, Limoniidae, Cylindrotomidae and Tipulidae s.s.]

Trichoceridae (winter crane flies)

Thaumaleidae

Other Interests:

Dung beetle (Scarabaeidae & Geotrupidae) biology (Master's thesis work)

scientific and other illustrations (traditional & computer generated), music, movies, PS2 games

Links:

- Catalogue of the Crane Flies of the World (Pjotr Oosterbroek)

- The Crane Flies of Pennsylvania (Chen Young)