THE INFLUENCE OF TEMPERATURE ON THE KINETICS OF ALLOGRAFT REACTIONS IN A TROPICAL SPONGE AND A REEF CORAL

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Abstract
Many tropical sponges and reef-building corals demonstrate highly discriminating transplantation immunity when grafted with allogeneic tissue. The speed of rejection changes seasonally, and therefore the role of temperature was investigated. Replicate parabiotic allografts of a Hawaiian sponge, Callyspongia diffusa, and a reef-coral, Montipora verrucosa, were exposed to 3 different temperature regimens; approximately 23.degree., 25.degree. and 27.degree. C. The primary allograft reactions were extremely temperature dependent in both species; the median reaction times (MRT) for the 1st-set grafts at summer temperatures (27.degree. C) were approximately 1/2 the winter temperature (23.degree. C) MRT. Significantly accelerated 2-set reactions in the coral were similarly affected by temperature; maximally accelerated 2-set reactions in the sponge were similar at all 3 temperatures. The primary mean reaction times for replicate grafts varied significantly among the individual genotypic combinations brought into parabiosis. Different genotypic combinations responded to temperature changes with qualitatively distinctive reaction trends and different reaction times. Parabiotic allografts mimic intraspecific interactions that are a consequence of natural contact through growth of sedentary marine animals. The influence of temperature on the outcome of intraspecific competition suggests that temperature fluctuations could maintain high levels of genetic polymorphism within individual populations of sponges and corals.