A marine dwelling eusocial organism: synalpheus regalis

Author: Esra Deniz Gumuser

Introduction

The major measure of success of an organism’s fitness is that the extent to which its genes are propagated through reproduction. Why, then, would an organism forgo the chance to spread copies of their genes by never reproducing? Several answers to this question have been formulated through experiments and observations of eusocial species found in the insect orders Hymenoptera and Isoptera (Wilson et al. 2005, Robinson 1992). One explanation is that ecological constraints create situations where eusociality is advantageous for both the reproductive individual and the non-reproducers (Buckle 1980). For instance, nests are difficult and dangerous to come by for most eusocial species, reducing the chances that a solitary individual could find another unoccupied nest, which is necessary for juveniles’ survival (Michener et al. 1974). Even if a nest is found, the solitary individuals are unable to defend their nests while foraging for food, resulting in a low survivorship of young due to predation (Batra 1966). In simple social species such as Liostenogaster flavolineata , adult worker females have a chance of becoming queen when the current one dies; thus becoming the sole reproductive individual (Bridge et al 2007). By remaining in natal nests to assist the development of juvenile siblings, adults forgo their opportunity to reproduce but still increase their fitness (copies of genes in future generations) through indirect measures and kin selection ( [link] ). Overall, in most social species including the sponge-dwelling shrimp Synalpheus regalis , eusociality arises due to ecological factors of limited food resources and shelter. These situations can be combated through the creation of castes that chiefly forage, defend, or reproduce—leading to the formation of eusociality (Crespi et al. 1995).