. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 284 M. ILAN AND V. LOYA. Figure 3. Chalinula sp. adull allografts, made by placing together the mesohyl of two fragments from different individuals and viewed through a scanning electron microscope, (a) Two allogeneic fragments. Arrow indicates the grafted area (scale bar = 1 mm), (b) Fragments A and B with a gap at the contact zone (scale bar = 100 ^m). (c) Higher magnification, reveals spicules erected toward the contact zone, presumably due lo cell disappearance from this area (scale bar = 100 ^m). (d) Formation of a pina
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 284 M. ILAN AND V. LOYA. Figure 3. Chalinula sp. adull allografts, made by placing together the mesohyl of two fragments from different individuals and viewed through a scanning electron microscope, (a) Two allogeneic fragments. Arrow indicates the grafted area (scale bar = 1 mm), (b) Fragments A and B with a gap at the contact zone (scale bar = 100 ^m). (c) Higher magnification, reveals spicules erected toward the contact zone, presumably due lo cell disappearance from this area (scale bar = 100 ^m). (d) Formation of a pinacoderm (P) layer by each fragment at the contact zone (scale bar = 30 ^m). time to onset of reproduction, which they have already started. We suggest, therefore, that the nonfusion of adult Chalinula sp. evolved because the disadvantages and risks involved are not outweighed by the chimeric benefits of larger total size. Considering the costs of participating in a chimera, we first assume that an organism acts to maintain its integrity, in order to pass on its genotype to the next generation. Several potential deleterious consequences of creating chimeras were proposed in the literature. Buss (1982, 1983) suggested a possible parasitism by one member of a chimera on the other: by differentiating its germ cells to gametes, it would take advantage of the other member's investment in somatic tissues for maintenance. Other workers have demonstrated oriented translocation of ma- terial in coral chimeras (Rinkevich and Loya, 1983), pos- sible transmission of pathogens (Buss, 1982), or in an as- cidian, total resorption of one member's soma by its part- ner, under laboratory mariculture (Rinkevich and Weissman, 1987. 1989). In this study, although all the chimeras survived at least 17 days, the fate of the cells of each partner was not determined. Chalinula sp. larval fusion has been observed exper- imentally in this study in the laboratory. However, its frequency in nature is unknown
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
