|
|
|
Abstract HISTORY OF THE SOCIAL SHRIMP DYNASTY: INSIGHTS FROM LONG-TERM RESEARCH AT THE SMITHSONIAN'S CARIBBEAN FIELD STATIONS J. Emmett Duffy1, Kenneth S. Macdonald
III2, Cheryl L. Morrison3, Rubén Ríos1,
and Eva Tóth4 Snapping shrimp in the genus Zuzalpheus (formerly Synalpheus, in part) are abundant and diverse residents of coral reef ecosystems worldwide and include the only marine animals known to live in eusocial colonies. Research conducted at the Smithsonian’s field stations at Carrie Bow Cay and in Caribbean Panama over nearly two decades has revealed much of the previously unknown natural history, ecology, and evolution of these unique and fascinating animals. We have described nine new species and a new genus of alpheids, documented host associations in detail, reconstructed the group’s phylogeny, observed behavior in captive colonies, and integrated these data to evaluate the ecological and evolutionary consequences of social life. Calibration of a molecular clock using three transisthmian species pairs suggests that Caribbean Zuzalpheus radiated rapidly ~6 Mya during closure of the Panama seaway. The improved taxonomy has shown that host associations of sponge-dwelling shrimp are much more specialized than previously believed. Comparative studies reveal that eusocial life has had pervasive consequences for shrimp morphological evolution, life history, and ecology. For example, after controlling for phylogenetic relatedness, eusociality is associated with smaller body size, and a switch in the direction of sexual dimorphism toward (paradoxically) relatively smaller females producing smaller clutches of eggs. Eusocial species also attain greater abundance and use a broader range of host sponges, supporting the hypothesis that sociality confers a competitive advantage in the crowded environment of the reef. Ongoing research uses social shrimp as a model for addressing general questions about animal social organization, focusing on how patterns of mating and dispersal influence the fine-scale genetic structure of social colonies, and how genetic relatedness in turn affects the balance between cooperation and conflict.
|