Award: OCE-1850837

Intellectual Merit The project investigated the environmental cues that induce cloning in echinoderms. We investigated the effects of a number of inductive cues on larval cloning in seastars, brittlestars, sea urchins and sand dollars and found that cloning was common in seastars and brittlestars but rare or absent in sea urchins and sand dollars. While previous reports suggest predatory cues my induce cloning, we found that other environmental factors like temperature and food supply were more likely to induce cloning. In addition, cloning appears to be a feature, rather than a bug, of development in many species, occurring even in the absence of any known cue. We examined the consequences of larval cloning in sea stars, where cloning via fission (splitting of the animal perpendicular to the anterior/posterior axis) is most common. In this case, both portions of the cloned animal are capable of regeneration and completion of the life cycle through metamorphosis. In addition, it appears that the limiting factor in regeneration success is a signal to begin the process. If absent, animals will survive but never regenerate. If present, all animals that began regeneration were able to successfully complete the process and metamorphose into a juvenile. This result will lead to future collaborations examining the molecular signals that induce regeneration to occur in these animals. We also found that there are previously unknown modes of cloning in brittlestars that reveal a hidden level of complexity in the life cycle of these animals. In particular, the larval arms of brittlestar larvae are able to be autotomized by the animal during development and a significant proportion of these arms will regenerate into an entirely new animal. The likelihood of regeneration of arms appears related to both temperature and population of origin, with animals from WA more likely to regenerate than those from ME and with both populations more likely to regenerate under cooler temperatures. The existence of this additional mode of cloning is an important addition to the life cycle of brittlestars and, when combined with prior studies of larval cloning in these animals, suggests a 'hypercomplex' life cycle (see figure) in these animals that goes well beyond what has been previously understood. Broader Impacts Completion of the work included the training of dozens of undergraduate students over the life of the grant, including several honors students. Many of these students are now enrolled in graduate schools (M.S. and Ph.D. programs) based in part on their accomplishments as part of our research team. In addition, the grant helped support the development of a new course for students on Marine Conservation Ecology that trained 18 students in the principles of marine ecology and conservation biology. Significant outreach was also accomplished through publication of our work in peer reviewed journals, regular presentations at the annual meeting of the Society for Integrative and Comparative Biology and multiple presentations to local and regional groups of concerned citizens through public lectures at, for example, a natural history museum and a land trust. Last Modified: 09/29/2023 Submitted by: Jonathan D Allen