| 1. |
- Kivelä, Sami M., et al.
(författare)
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Comparative analysis of larval growth in Lepidoptera reveals instar-level constraints
- 2020
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 34:7, s. 1391-1403
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Tidskriftsartikel (refereegranskat)abstract
- 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. 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. We studied ontogenetic changes and allometry in instar-specific characteristics of larval growth in 30 lepidopteran species in a phylogenetic comparative framework. 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 in both RMI and GD. 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.
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| 2. |
- Kjaersgaard, Anders, et al.
(författare)
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Weak sex-specific evolution of locomotor activity of Sepsis punctum (Diptera : Sepsidae) thermal experimental evolution lines
- 2023
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Ingår i: Journal of Thermal Biology. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0306-4565 .- 1879-0992. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- Elevated temperatures are expected to rise beyond what the physiology of many organisms can tolerate. Behavioural responses facilitating microhabitat shifts may mitigate some of this increased thermal selection on physiology, but behaviours are themselves mediated by physiology, and any behavioural response may trade-off against other fitness-related activities. We investigated whether experimental evolution in different thermal regimes (Cold: 15 degrees C; Hot: 31 degrees C; Intergenerational fluctuation 15/31 degrees C; Control: 23 degrees C) resulted in genetic differentiation of standard locomotor activity in the dung fly Sepsis punctum. We assessed individual locomotor performance, an integral part of most behavioral repertoires, across eight warm temperatures from 24 degrees C to 45 degrees C using an automated device. We found no evidence for generalist-specialist trade-offs (i.e. changes in the breadth of the performance curve) for this trait. Instead, at the warmest assay temperatures hot-selected flies showed somewhat higher maximal performance than all other, especially cold-selected flies, overall more so in males than females. Yet, the flies' temperature optimum was not higher than that of the cold-selected flies, as expected under the 'hotter-is-better' hypothesis. Maximal locomotor performance merely weakly increased with body size. These results suggest that thermal performance curves are unlikely to evolve as an entity according to theory, and that locomotor activity is a trait of limited use in revealing thermal adaptation.
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