title: Developmental constraints in cave beetles.
abstract: In insects, whilst variations in life cycles are common, the basic patterns typical for particular groups remain generally conserved. One of the more extreme modifications is found in some subterranean beetles of the tribe Leptodirini, in which the number of larval instars is reduced from the ancestral three to two and ultimately one, which is not active and does not feed. We analysed all available data on the duration and size of the different developmental stages and compared them in a phylogenetic context. The total duration of development was found to be strongly conserved, irrespective of geographical location, habitat type, number of instars and feeding behaviour of the larvae, with a single alteration of the developmental pattern in a clade of cave species in southeast France. We also found a strong correlation of the size of the first instar larva with adult size, again regardless of geographical location, ecology and type of life cycle. Both results suggest the presence of deeply conserved constraints in the timing and energy requirements of larval development. Past focus on more apparent changes, such as the number of larval instars, may mask more deeply conserved ontogenetic patterns in developmental timing.
authors.affiliation: Museo Nacional de Ciencias Naturales (MNCN, CSIC), Madrid, Spain Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Maritim de la Barceloneta 37-49, Barcelona 08003, Spain a.cieslak@gmx.net.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Cieslak
authors.affiliation: Museu de Ciències Naturals (Zoologia), Barcelona, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Fresneda
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Passeig Maritim de la Barceloneta 37-49, Barcelona 08003, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Ribera
mesh_terms: D000220:Adaptation, Biological / Q000502:physiology*; D000818:Animals; D049628:Body Size; D059552:Caves; D001517:Coleoptera / Q000254:growth & development*; D017753:Ecosystem; D005247:Feeding Behavior; D005602:France; D007814:Larva / Q000254:growth & development*; D008018:Life Cycle Stages / Q000502:physiology*; D010802:Phylogeny; D058974:Phylogeography
keywords: developmental constraints; larval development; life cycle; subterranean environment