Caenorhabditisnematodes colonize ephemeral resource patches in neotropical forests

Abstract

Factors shaping the distribution and abundance of species include life‐history traits, population structure, and stochastic colonization–extinction dynamics. Field studies of model species groups help reveal the roles of these factors. Species of Caenorhabditis nematodes are highly divergent at the sequence level but exhibit highly conserved morphology, and many of these species live in sympatry on microbe‐rich patches of rotten material. Here, we use field experiments and large‐scale opportunistic collections to investigate species composition, abundance, and colonization efficiency of Caenorhabditis species in two of the world's best‐studied lowland tropical field sites: Barro Colorado Island in Panamá and La Selva in Sarapiquí, Costa Rica. We observed seven species of Caenorhabditis , four of them known only from these collections. We formally describe two species and place them within the Caenorhabditis phylogeny. While these localities contain species from many parts of the phylogeny, both localities were dominated by globally distributed androdiecious species. We found that Caenorhabditis individuals were able to colonize baits accessible only through phoresy and preferentially colonized baits that were in direct contact with the ground. We estimate the number of colonization events per patch to be low.

Widespread changes in gene expression accompany body size evolution in nematodes

“…Additionally, hermaphroditic species tend to have less complex and less sex-biased transcriptomes than gonochoristic species (when considering adults) (Thomas et al 2012), and a transgenic reporter construct survey with eight genes and four Caenorhabditis species revealed widespread spatial variation in gene expression (Barrière and Ruvinsky 2014). Notably, over half of the genes examined C. inopinata and C. elegans (Sloat et al 2022), this lends support to the view that developmental system drift in transcriptomes is common in this group. Regardless, future studies that capture a larger phylogenetic sample as well as a range of postembryonic stages will be required to disentangle these possibilities.…”

“…2021). As these species are far more closely related to each other than C. inopinata and C. elegans (Sloat et al . 2022), this lends support to the view that developmental system drift in transcriptomes is common in this group.…”

Diet can alter the cost of resistance to a natural parasite in Caenorhabditis elegans

“…We chose to measure fitness through population expansion because of the ecology of C. elegans . In the wild, one to a few nematodes colonize a transient microbial resource, reproduce rapidly, predominantly via self‐fertilization, then disperse to a new patch (Félix & Braendle, 2010 ; Richaud et al, 2018 ; Sloat et al, 2022 ). These microbial resources are highly ephemeral, so demes that reach large population sizes quickly are expected to produce more migrants to colonize new patches.…”

“…This result contrasts with prior studies that found a cost of resistance only in food-limited contexts (Boots, 2011;Kraaijeveld & Godfray, 1997) We chose to measure fitness through population expansion because of the ecology of C. elegans. In the wild, one to a few nematodes colonize a transient microbial resource, reproduce rapidly, predominantly via self-fertilization, then disperse to a new patch (Félix & Braendle, 2010;Richaud et al, 2018;Sloat et al, 2022).…”

Corrigendum

“…In the recent article by Sloat et al ( 2022 ), the following sentence was missed in the Acknowledgments section.…”