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Comparative analysis of larval growth in Lepidoptera reveals instar-level constraints

Citation

Kivelä, Sami et al. (2020), Comparative analysis of larval growth in Lepidoptera reveals instar-level constraints, Dryad, Dataset, https://doi.org/10.5061/dryad.p2ngf1vmz

Abstract

1. Juvenile growth trajectories evolve via the interplay of selective pressures on age and size at maturity, and developmental constraints. In insects, the moulting cycle is a major constraint on larval growth trajectories. 2. Surface area to volume ratio of a larva decreases during growth, so renewal of certain surfaces by moulting is likely needed for the maintenance of physiological efficiency. A null hypothesis of isometry, implied by Dyar’s Rule, would mean that the relative measures of growth remain constant across moults and instars. 3. We studied ontogenetic changes and allometry in instar-specific characteristics of larval growth in 30 lepidopteran species in a phylogenetic comparative framework. 4. Relative instar-specific mass increments (RMI) typically, but not invariably, decreased across instars. Ontogenetic change in RMIs varied among families with little within-family variation. End-of-instar growth deceleration (GD) became stronger with increasing body size across instars. Across-instar change in GD was conserved across taxa. Ontogenetic allometry was generally non-isometric both in RMI and GD. 5. Results indicate that detailed studies on multiple species are needed for generalizations concerning growth trajectory evolution. Developmental and physiological mechanisms affecting growth trajectory evolution show different degrees of evolutionary conservatism, which must be incorporated into models of age and size at maturation.

Methods

Phenotypic data were collected by measuring growing larvae under controlled laboratory conditions. Data have been converted in a format that can be used in statistical analyses.

Funding

Suomen Kulttuurirahasto

Emil Aaltosen Säätiö

Eesti Teadusagentuur, Award: PUT1474

Stockholms Universitet, International fellowship program

Academy of Finland, Award: 314833

Academy of Finland, Award: 319898

Academy of Finland, Award: 277984

Institutional research funding IUT*, Award: IUT20-33

Estonian Ministry of Education

Stockholms Universitet, Bolin Centre for Climate Research

Vetenskapsrådet, Award: VR 2017-04500

Stockholms Universitet, International fellowship program

Institutional research funding IUT, Award: IUT20-33

Estonian Ministry of Education

Stockholms Universitet, Bolin Centre for Climate Research