Allometric growth of two species of Ephemeroptera from Neotropical mountains streams

Abstract

-The present study evaluated the relative growth and allometry of Massartella brieni Lestage and Thraulodes sp. (Leptophlebiidae: Ephemeroptera). The morphometric analysis was based on 23 measurements and was conducted using a multivariate approach. Throughout postembryonic ontogeny, all of the head measurements, including those of the mouthparts, exhibited negative allometric growth. The mesothorax and wing pad exhibited positive allometric growth. The hind legs lengths in M. brieni and the fore and hind legs lengths in Thraulodes sp. exhibited positive allometry. The abdominal length in these two species exhibited positive allometric growth. Positive allometry was also observed along the abdomen width for M. brieni, and isometry was observed for Thraulodes sp. The relative strengthening of the thorax (in preparation for the winged stage) and the relative increase in the abdomen (which may be related to the development of the reproductive structures) during growth indicate that many of the structures that exhibit positive allometric growth are related to the transition from the aquatic to the adult stage of development.

Allometry of exaggerated mandibular tusks in the burrowing mayfly Rhoenanthus coreanus (Ephemeroptera: Potamanthidae)

“…Indeed, de Paula et al (2012 even reported that "according to size-grain hypothesis, natural selection would favor smaller legs in small individuals and larger legs in large individuals." The size-grain hypothesis states that smaller legs are more efficient for interstitial movement, whereas larger legs facilitate fossorial behavior or locomotion across obstacles (de Paula et al 2012). Interestingly, the analysis of EL yielded much different results.…”

“…(Painting & Holwell 2013). However, in other mayflies without exaggerated tusks, such as members of the genus Thraulodes (Leptophlebiidae), legs have been reported to exhibit positive allometry (de Paula et al 2012). Indeed, de Paula et al (2012 even reported that "according to size-grain hypothesis, natural selection would favor smaller legs in small individuals and larger legs in large individuals."…”

“…allometry). As such, insect growth is generally considered allometric, and the diversity of species phenotypes is mostly determined by allometry and shape variations (de Paula et al 2012). Interestingly, insect growth can sometimes progress disproportionately and, thus, result in the generation of exaggerated traits (i.e.…”

Neither silverfish nor fowl: the enigmatic Carboniferous Carbotriplura kukalovaeKluge, 1996 (Insecta: Carbotriplurida) is the putative fossil sister group of winged insects (Insecta: Pterygota)

“…According to Kukalová-Peck (1978), wing pads in Paleozoic insect nymphs were growing gradually in posterolateral direction throughout larval development. Even if we assume a positive allometric growth of wing pads like in modern mayfly nymphs (Maxwell & Benson, 1963;de Paula Paciencia et al, 2012), this specimen with an extraordinary body length of already 10 cm (!) excluding terminal filaments would need to develop into an adult much larger than any other Paleozoic insect discovered so far.…”

A geometric morphometric approach to establish body-shape trait criteria for aquatic insects

“…Traditional morphometric approaches (sensu Rohlf and Marcus 1993) rely on measurements of distances between morphological features, including specific body regions or lengths of structures, to describe shape and infer ecological or evolutionarily relationships. Measurement-based approaches have been applied to a limited number of larval (Sheldon 1980, Funk et al 2008, Giacomini and de Marco 2008, de Paula Paciencia et al 2012 and adult (Hogue and Hawkins 1991, Ribera and Nilsson 1995, Müller-Peddinghaus and Hering 2013 aquatic insect taxa. A geometric morphometrics (GM) approach for describing organismal shape uses configurations of key morphological points or landmarks to delineate the shape of individual structures (e.g., animal skulls; Rohlf et al 1996) or entire body forms (e.g., Haas et al 2010, Farré et al 2013.…”