Dragonflies community assembly in artificial habitats: Glimpses from field and manipulative experiments

Abstract

Several factors act on community structure, so determining species composition and abundance patterns. Core processes operating at local scales, such as species-environment matching and species interactions, shape observed assemblages. Artificial habitats (simplified structure) are useful systems for assessing the main factors affecting community composition and disentangling their assembly rules. Drinking troughs (brickwork tanks for free-ranging cattle watering) are widespread in Italy and represent a suitable aquatic habitat for colonization by various aquatic organisms. Dragonflies larvae are usually found in drinking troughs and often exhibit strong species interactions and striking community assembly patterns. Our primary aim was to search for Odonata communities exhibiting non-random co-occurrence/segregation patterns in drinking troughs. We performed null-model analyses by measuring a co-occurrence index (C-score) on larval Odonata assemblages (13 species from 28 distinct troughs). Overall, we found a non-random structure for the studied dragonfly assemblages, which, given their fast generation time, must have been generated by short-term ecological processes (i.e. interspecific interactions). We thus analyzed potential competition/predation among and within ecological guilds. From the field data, we speculated that interactions within the sprawlers’ guild is likely among the main drivers structuring the studied assemblages, especially the effect of intraguild predation between C . erythraea and Sympetrum spp larval stages. We then experimentally tested these interactions in laboratory and demonstrated that intraguild predation among larvae at different development stages may result in an effective exclusion/negative impact on density pattern, representing one of the processes to take into consideration when studying dragonfly assemblages.

If you build it, they will come: rapid colonization by dragonflies in a new effluent-dependent river reach

“…We focused our surveys on odonates for several reasons. First, they tend to be strong dispersers and are known to colonize novel anthropogenic habitats (Corbet, 1999;Prescott & Eason, 2018;Cerini, Bologna & Vignoli, 2019). Second, diverse assemblages of odonates have been found in urban water bodies in many cities (Willigalla & Fartmann, 2012;Goertzen & Suhling, 2015;Holtmann et al, 2018).…”

Patterns of co‐occurrence and body size in dragonflies and damselflies (Insecta: Odonata) in preserved and altered Amazonian streams

“…However, other factors (e.g. environmental filtering) may also have been a possible mechanism underlying the chessboard distributions observed in Zygoptera, mainly in preserved streams (Cerini et al 2019;Dallas et al 2019). Sympatric congener species tend to differ at a microhabitat scale, given that they usually exploit food resources in a similar fashion (Johannsson 1978), resulting in the exclusion of the least competitive species (Khelifa et al 2013).…”

“…Although the deterministic theory on the distribution of species in the community prevails in community ecology (Grant 1972;Diamond 1975;Stone & Roberts 1990), many papers have shown that well-defined distribution patterns are absent in many communities (Volkov et al 2003;McGill et al 2006). As few studies have elucidated the role of competition in structuring odonate communities, the competition between closely related species would be expected to be more intense and likely to cause habitat segregation (Pires et al 2017;Cerini et al 2019).…”

Peer Review #3 of "If you build it, they will come: rapid colonization by dragonflies in a new effluent-dependent river reach (v0.1)"

“…We focused our surveys on odonates for several reasons. First, they tend to be strong dispersers and are known to colonize novel anthropogenic habitats (Corbet, 1999;Prescott & Eason, 2018;Cerini et al, 2019). Second, diverse assemblages of odonates have been found in urban water bodies in many cities (Willigalla & Fartmann, 2012;Goertzen & Suhling, 2015;Holtmann et al, 2018).…”