Effects of shape variations on the energy metabolism of the sand cricket Gryllus firmus: a geometric morphometric analysis

Abstract

Respiration and energy metabolism are key processes in animals, which are severely constrained by the design of physical structures, such as respiratory structures. Insects have very particular respiratory systems, based on gas diffusion across tracheae. Since the effi ciency of the tracheal respiratory system is highly dependent on body shape, the pattern of morphological variation during ontogeny could have important metabolic consequences. We studied this problem combining through-fl ow respirometry and geometric morphometrics in 88 nymphs of the sand cricket, Gryllus fi rmus. After measuring CO 2 production in each individual, we took digital photographs and defi ned eight landmarks for geometric morphometric analysis. The analysis suggested that ontogenic deformations were mostly related to enlargement of the abdomen, compared to thorax and head. We found that (controlling for body size) metabolic variables and especially resting metabolism are positively correlated with a shape-component associated to an elongation of the abdomen. Our results are in agreement with the mechanics of tracheal ventilation in orthopterans, as gas circulation occurs by changes in abdominal pressures due to abdominal contractions and expansions along the longitudinal axis.

Metabolism, Growth, and the Energetic Definition of Fitness: A Quantitative Genetic Study in the Land SnailCornu aspersum

“…Today, few estimations of genetic (co)variances for bioenergetic traits in invertebrates are available, which contrasts with the complete picture of the heritable variation and fitness covariation of energy metabolism in vertebrates (see Nespolo et al 2005;Ronning et al 2007;Wone et al 2009 and references therein). In fact, we have been unable to find quantitative genetic studies of invertebrate energy metabolism other than in insects (Rantala and Roff 2006;Nespolo et al 2007Nespolo et al , 2011Ketola and Kotiaho 2009;Arnqvist et al 2010;Jumbo-Lucioni et al 2010;Artacho et al 2011;Piiroinen et al 2011), which indeed show low levels of additive genetic variation. This omission needs attention since noninsect invertebrates represent a vast proportion of multicellular animals inhabiting a broad array of habitats and, hence, exhibiting varied physiological adaptations.…”

High Repeatability of Anti-Predator Responses and Resting Metabolic Rate in a Beetle

“…Individuals with different body mass and body size have different lifehistory values (e.g. Krams et al 2011a;Nespolo et al 2011) and may thus differ in the expression of behaviors. Therefore, we excluded nearly 20 % consisting of the smallest and largest beetles from this time-consuming study and to be able collect a sufficient sample size study, which was restricted to male individuals only (n=60).…”

The tracheal system in post‐embryonic development of holometabolous insects: a case study using the mealworm beetle

“…; Contreras & Bradley, ; Moerbitz & Hetz, ; Nespolo et al. ; Sláma & Jedlička, ), the structure of the tracheal system remains poorly investigated. Earlier works addressing this issue were based on dissections and illustrated with handmade drawings (e.g.…”

“…Although the phenomenon of gas exchange is one of the major research trends in insect physiology Harrison et al 2005;Jõgar et al 2005;Lease et al 2006;Greenlee et al 2009;Contreras & Bradley, 2010;Moerbitz & Hetz, 2010;Nespolo et al 2011;Sl ama & Jedli cka, 2012), the structure of the tracheal system remains poorly investigated. Earlier works addressing this issue were based on dissections and illustrated with handmade drawings (e.g.…”