EVOLUTION OF THE INSECTA

REFERENCES:

DeSalle, R. et al. 1992. DNA sequences from a fossil termite... Science. 257: 1933-1936.

Emerson, M. and F. Schram. 1990. The origin of crustacean biramous appendages and the evolution of arthropoda. Science. 250: 667-669.

Jeram, A. et al. 1990. Land animals in the Silurian: arachnids and myriapods from Shropshire, England. Science. 250: 658-661

Kukalova-Peck, Jarmila. 1992. Canadian Journal of Zoology 70: 236-255.

Labandeira, C. et al. 1988. Early insect diversification: evidence from a Lower Devonian bristletail from Quebec. Science. 242: 913-916.

Labandeira, C. and J. Sepkoski. 1996. Insect diversity in the fossil record. Science 261: 310-315.

Morell, V. 1992. 30-million-year-old DNA boosts an emerging field. Science. 257: 1860-1862.

Robinson, R. 1990. Earliest-known uniramous arthropod. Nature. 343: 163-164.

Shear, W. 1992. End of the uniramia taxon. Nature. 359: 477-478.

Question - what group are insects most closely allied to?

collembola and (doubtful?) microcoryphia known along with arachnids from Devonian

oldest insect fossils (about 350,000,000 years old) already have wings and are fully insects

upper Carboniferous (300,000,000 years ago): modern groups are found, including giant roaches

Permian: modern groups and paleodictyopteroids are dominant (280,000,000 yrs. ago), including first holometabolous insects

Meganeuron the largest insect ever at 75cm wingspan, lived then

Mezozoic: only few orders not found today survived

Cretaceous: (65,000,000 yrs. ago) nearly all modern orders known, many modern families and even genera: New Jersey amber

Cenozoic: nearly all fossils assignable to extant families

 

Evidence from modern relationships

Arthropods closest in appearence to Annelida and Onycophora

Arthropods show

  1. sclerotization

  2. cephalization

  3. tagmatization

  4. no subdivision of body cavity

  5. open circulation

  6. respiration by tracheae

Relations within Arthropoda

Theories of insect origin have included attempts to derive insects from Onychophora, Annelida, Trilobites, larvae of Crustacea, and Chilopods.

R. J. Tillyard did embryological work to establish Chilopods as most likely group, but no living forms could be ancestral. [Tillyard known for his mystical streak; claimed once to have visited the Permian??]

Tiegs and Manton established idea of Uniramia, distinct from biramous Crustacea and chelicerates

Kukalova-Peck, looking at fossils, hypothesized a common origin for all appendages in Crustacea-Myriapoda-Insecta, from an initially 11-segmented condition

Molecular studies seem to imply a close relation of Insecta-Crustacea, but put Myriapods closer to Chelicerata-Trilobita

Molecular studies from recent work by Kjer, et al at Rutgers

Relations within Insecta

See Tree of Life and Phylogeny web sites

EVOLUTION OF WINGS AND FLIGHT

REFERENCES:

Brodsky, A.K. 1994. The Evolution of Insect Flight. Oxford Univ. Press. 248pp.

Carle, Frank. 1982. Thoughts on the origin of insect flight. Ent. News 93: 159-172.

Kaiser, J. 1994. A new theory of insect wing origin takes off. Science. 266: 363-.

Kukalova-Peck, Jarmila. 1992. Canadian Journal of Zoology 70: 236-255.

Lewin, R. 1985. On the origin of insect wings. Science. 230: 428-429.

Marden, J. and M. Kramer. 1994. Surface-skimming stoneflies: a possible intermediate stage in insect flight evolution. Science. 266: 427-430.

Marden, J and M. Kramer. 1995. Locomoter performance of insects with rudimentary wings. Nature 377: 332-334

Matsuda, R. 1981. The origin of insect wings. Int. J. Insect Morphol. & Embryol. 10:387-398

Truman, J. and L. Riddiford. 1999. The origins of insect metamorphosis. Nature 401: 447-452.

Will, Kipling. 1995. Plecopteran surface-skimming and insect flight evolution. Science 270: 1684-1685

response: Marden and Kramer. Science 270: 1685.

How did insects evolve wings?

What part of insect body evolved into wings?

  1. Outgrowths of pleura (side of thoracic segment) possibly used as gills
  2. Paranotal lobes (top sclerite of thoracic segment) Seen on T1-T3 in some early fossils
  3. Portions of segmental appendage (leg)
    Style on sub coxa, possibly used as a gill
    Branch of a basal segment above the spiracle (Kukulova-Peck 1992)
  4. Fossils not yet discovered to solve this problem

What was original function of wings before flight was possible?

  1. Gills - explains tracheae and hemocoel in wings
    muscles might have been used to increase flow over gills
    wing pads may act as supplemental gills in some extant forms
  2. Sex display or Defense - startle displays
    more effective if moved
    early wing fossils show patterns
    doesn’t explain tracheae or hemocoel
  3. Thermoregulation
    doesn’t explain origin of wing muscles
    transition from thermoregulation to flight has been shown to be possible in theory, if insect body size had changed from other causes (Lewin, 1985)
  4. Water skimming

seen in modern stoneflies, mayflies
allows wings to be useful even if small (as little as 20% of wing length)
could be derived from ventilatory movements of gill plates

Where did flight evolve?

  1. Carle (1982) suggests in seepage streams
  2. paleozoic landscape before forests would be wetter
    unshaded springs very productive - many aquatic larvae
    adults would have laid eggs on land
  3. adaptation to counter downstream drift of larvae
  4. gills might have become adapted to surface skimming; this would gradually lead to take-off

How many times did flight evolve?

  1. some investigators regard winged insects as polyphyletic (Matsuda, 1981)
  2. majority favor monophyletic origin
  3. Marden and Kramer (1995) defend idea flight could have evolved more than once

How did insect metamorphis evolve?

See Truman, J. and L. Riddiford. 1999.

  1. "pronymph (hatchling)" = larva
  2. nymph = pupa
  3. adult = adult
  4. based on endocrinlogy