Morphology of dragonfly larvae along a habitat gradient: interactions with feeding behaviour and growth (Odonata: Libellulidae)

Abstract

It has been shown that life history, behavioural as well as morphological traits vary with the habitats occupied by odonate larvae. Here we ask the following questions:(1) Are the morphological traits, which are associated with perception and foraging, related to the larval habitat? (2) Do these traits influence foraging success and growth rate? We analysed the morphology of species pairs belonging to the genera Crocothemis, Orthetrum and Trithemis; one species in each pair occurring in perennial spring-fed streams, the other able to develop in temporary waters. A PCA reveals four principal components of morphological characters which may be expressed as PC1: prey handling, PC2: visual perception, and PC3 and PC4: density of long and short setae on the feet. The variances of PC1, PC2 and PC3 were affected by phylogeny. PC1, PC2 and PC4 differed between habitats. Species of perennial springs had larger values for visual perception. These waters are clear and larger eyes should be beneficial. But, a high PC2 value was associated with low growth rate and did not affect foraging success. We therefore conclude that investment in better sight made by perennial water species may reflect the need of avoiding predators. Development in temporary waters mainly requires rapid growth and species may not be capable to invest also in visual perception. PC1 was negatively correlated with foraging behaviour and PC3 was positively so. This indicates the importance of prey capture mode to foraging success, which may, however, not translate into a higher growth rate.

Useful biometric variables in Iberian exuviae of Boyeria irene (Fonscolombe, 1838) (Odonata: Aeshnidae)

“…However, less attention has been paid to the intraspecific biometric variation in odonate larvae. In this sense, larval morphological characters vary with the habitat type occupied (Sahlén et al, 2008). Larvae living on the bottoms of streams, as is the case with B. irene (Velasco et al, 2018), may invest less in direct foraging organs (Giacomini & De Marco, 2008) and more in an effective system for reducing predation risk.…”

“…There are numerous variables that can be measured in exuviae and larvae (Doucet, 2010), and their selection will depend on the species being analyzed. So, for example, the lateral or back spines are measured for the purposes of studying their antipredator function (Sahlén et al, 2008;McCauley et al, 2008;Leipelt et al 2010;Johansson et al, 2017), while their prementum length can be measured to study their effectiveness in capturing prey (Lagrue et al, 2011).…”

Distribution Patterns of Odonate Assemblages in Relation to Environmental Variables in Streams of South Korea

“…Sampling sites in cluster F were mostly from agricultural and urban land areas with low canopy coverage and high turbidity. These environmental characteristics were well characterized by the indicator species O. albistylum which is a tactile predator [50] and is tolerant to physicochemical pollution [44]. As they are more competitive than visual predators in turbid environments, they may dominate in these sampling sites.…”

Biometric differences across three populations of Boyeria irene from the southern Iberian Peninsula (Odonata: Aeshnidae)

“…Nearby populations within around 300 km only show size range differences in several anatomical structures, especially in female larvae. The Sierra de Córdoba population has been characterized by being that with the longest lateral abdominal spines and paraproct; perhaps an effective system for reducing predation risk (Mikolajewski et al 2006;Giacomini & De Marco 2008;Sahlén et al 2008). According to Tennessen (2019) and Nunes et al (2021a), a better knowledge of the morphological differences between populations would help to improve management and conservation of the various Odonata species.…”