Is earthworms' dispersal facilitated by the ecosystem engineering activities of conspecifics?

Abstract

short communicationInternational audienceIn this work, we documented the influence of earthworm's galleries on their speed of movements during dispersal events in the soil. We quantified, by using X-rays, the dispersal behaviour of earthworms in the soil. The observations were conducted in mesocosms in controlled conditions for 12 h. Our experiments revealed that during a dispersal sequence of a batch of individuals of the species Aporrectodea terrestris (Savigny 1826): (a) individuals used preferentially existing conspecifics' galleries, (b) individual velocity increased after each dispersal event and (c) the lag time before each dispersal event did not seem to be influenced by previous dispersers. Therefore, dispersal seems to be facilitated by conspecifics' activity, which strongly supports the hypothesis of a feedback between ecosystem engineers' activity and their dispersal spee

How good are epigeic earthworms at dispersing? An investigation to compare epigeic to endogeic and anecic groups

“…Nonetheless, to our knowledge, few studies have investigated the environmental factors that influence dispersal behaviour in earthworms. Caro et al (2013Caro et al ( , 2012 and Mathieu et al (2010) showed that low soil quality increased dispersal rate of Aporrectodea icterica, Allolobophora chlorotica, Aporrectodea caliginosa (endogeic species) and of Aporrectodea longa, Lumbricus terrestris and Aporrectodea giardi (anecic species) (Caro et al, 2013;Mathieu et al, 2010). Moreover, the absence of litter increased dispersal rate in Dendrobaena venata, an epigeic species (Mathieu et al, 2010).…”

“…Moreover, the amount of food in the environment is often limited; therefore, food availability per individual is negatively correlated with population density (Curry, 1998). Alternatively, population density may affect soil physical and chemical properties (Jones et al, 2010(Jones et al, , 1994Rillig et al, 2016), which may lead to facilitating mechanisms (Caro et al, 2012;Mathieu et al, 2010).…”

Pore structure, stability and water repellency of earthworm casts and natural aggregates in loess soil

“…Through the high levels of cast production, the earthworms control the changes in soil aggregation to much more extent than plant roots (e.g., Blanchart et al, 2004b) and are identified as the most important soil ecosystem engineers (Lavelle, 2011). The earthworm activities are highly variable depending on environmental conditions (Eijsackers, 2011;Caro et al, 2012) and enhanced more in areas previously burrowed than new habitats (Caro et al, 2012).…”

Landscape features impact connectivity between soil populations: a comparative study of gene flow in earthworms

“…; Caro et al . , ). The distribution of these restricted dispersers is known to be controlled by soil parameters at the field scale and by land use (forest, grassland and agricultural field), soil management, soil type and climatic conditions at scales exceeding the field level; studies at the landscape scale are thus challenging because fine‐scale heterogeneity and gradients affecting regional‐scale patterns have to be accounted for (Palm et al .…”

“…species living in the upper organo-mineral soil layers and forming horizontal nonpermanent burrows, Bouch e 1977) and anecic (i.e. species forming permanent or semi-permanent vertical burrows in the soil which open at the surface where the earthworm emerges to feed, Bouch e 1977) species (Mathieu et al 2010;Caro et al 2012Caro et al , 2013. The distribution of these restricted dispersers is known to be controlled by soil parameters at the field scale and by land use (forest, grassland and agricultural field), soil management, soil type and climatic conditions at scales exceeding the field level; studies at the landscape scale are thus challenging because fine-scale heterogeneity and gradients affecting regional-scale patterns have to be accounted for (Palm et al 2013).…”