Phenotypic plasticity in pre-feeding larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius

Abstract

Experimental studies showed that in echinoids egg size of a species affects magnitude of phenotypic plasticity in larvae of the species. Here we tested whether any difference in magnitude of plasticity exists in pre-feeding larvae of two sea urchins, Mesocentrotus nudus (A. Agassiz, 1864) and Strongylocentrotus intermedius (A. Agassiz, 1864). These species are closely related by their phylogenetic position, have overlapping ranges, and differ by size of their eggs. Our results indicate that by the end of pre-feeding development (4 d after fertilization) the larvae from high algae treatment (8 000 cells 1 ml-1) had shorter post-oral arms as compared to their siblings of the same age from no algae treatment (0 cells 1 ml-1). In spite the egg volume of M. nudus was approximately 2-times bigger than that in S. intermedius, relative difference in post-oral arms length in no algae and high algae conditions in S. intermedius was approximately 1.5 times larger. Our results support the assumption that the degree of phenotypic plasticity in the larvae, developing from smaller eggs with lower maternal investment, is higher than in the larvae, developing from bigger eggs. We propose that pre-feeding larvae of S. intermedius are more phenotypically plastic than the larvae of M. nudus.

Effect of dopamine on early larvae of sea urchins, Mesocentrotus nudus and Strongylocentrotus intermedius

“…Many studies of phenotypic plasticity in echinoid larvae assumed that when developing in food-limited environment the larvae invest Earlier we found that larvae of these sea urchins differed from one another in the magnitude of post-oral arm growth depending on concentration of microalgae in the water. Our results (Kalachev et al, 2018) indicate that M. nudus larvae grown under low-and high-algae conditions had shorter post-oral arms by 5% and 9%, respectively, as compared with their siblings from the no-algae group. On the contrary, S. intermedius larvae grown under low-and high-algae condition had their post-oral arms by 2% and 13% shorter, respectively, than those in the larvae from the no-algae group (Kalachev et al, 2018).…”

“…Our results (Kalachev et al, 2018) indicate that M. nudus larvae grown under low-and high-algae conditions had shorter post-oral arms by 5% and 9%, respectively, as compared with their siblings from the no-algae group. On the contrary, S. intermedius larvae grown under low-and high-algae condition had their post-oral arms by 2% and 13% shorter, respectively, than those in the larvae from the no-algae group (Kalachev et al, 2018).…”

“…For details on the number of animals used for crossing in each replicate, see Table 1. Larvae were reared as described earlier by Kalachev et al (2018). In brief, 24-h-old embryos were partitioned into 5-L glass beakers with filtered and aerated sea water at a density of 1 embryo per 1 ml.…”

Bacterial Exposure Mediates Developmental Plasticity and Resistance to Lethal Vibrio lentus Infection in Purple Sea Urchin (Strongylocentrotus purpuratus) Larvae

“…Morphological plasticity is well-described in echinoderm larvae (36,37,39) [Reviewed in (34,35)]. In this study, we found that the sizes of multiple larval structures were associated with differences in bacterial exposure during development.…”

“…Planktotrophic larvae tend to undergo a plastic response to fluctuating food availability. Specifically, under low-food conditions, the lengths of the larval arms, used for feeding, are increased relative to larval body length, while overall gut volume is reduced (35)(36)(37)(38)(39). Recently, Carrier and Reitzel (28) correlated feeding-induced plasticity with structural changes in the associated bacterial microbiota of three confamilial sea urchins (S. purpuratus, S. droebachiensis, and Mesocentrotus franciscanus), underscoring a role for microbes in larval development (19,31).…”