. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. COLONY GROWTH OF POLYCLINUM 95 6000 -i I S 4000 - o B _O O U 2000 - 0 - = 12 18 24 Colony Age (months) Figure 8. The relationship between colony age and colony size for Polvcliinim planum collected in May 1992 (n = 77 colonies). The solid line indicates the linear regression, which was significant at « = (1989) that this is a nonfragmenting species and means that each P. planum colony represents an entire genet. As such, the loss of a P. planum colony is a greater loss, in an evolutionary sense, than if it were
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. COLONY GROWTH OF POLYCLINUM 95 6000 -i I S 4000 - o B _O O U 2000 - 0 - = 12 18 24 Colony Age (months) Figure 8. The relationship between colony age and colony size for Polvcliinim planum collected in May 1992 (n = 77 colonies). The solid line indicates the linear regression, which was significant at « = (1989) that this is a nonfragmenting species and means that each P. planum colony represents an entire genet. As such, the loss of a P. planum colony is a greater loss, in an evolutionary sense, than if it were only one of several physiologically isolated ramets. P. planum has conse- quently developed growth-related adaptations that in- crease the chances of colony survivorship even in physi- cally stressful intertidal environments. The most obvious ecological risk to erect, though flex- ible, intertidal colonies of P. planum is dislodgement by water-flow forces. Denny el al. (1985) demonstrated how such forces can dislodge or limit the size of intertidal or- ganisms living in wave-impacted environments. Since intertidal P. planum colonies are subjected to those kinds of water flow forces, it is not surprising that this species exhibits growth-related adaptations for dealing with stresses associated with water flow. The pattern of P. pla- num colony growth reveals two strategies for mitigating the effects of water flow: (1) an attenuating pattern of growth; and (2) allometric expansion of the zooid-bear- ing lobe into a laterally flattened structure. Attenuating growth, like that demonstrated by P. pla- num (see Fig. 2), is common among colony-forming modular organisms such as corals (Hughes and Connell, 1987; Karlson, 1988;Lasker, 1990),bryozoans(Hughes, 1990; Kauffman. 1981). and ascidians (Ryland el al, 1984; Stoner, 1989; Stocker, 1991). In the case of P. pla- num, it appears that environmental stress limits colony size. The general pattern of P. planum's attenuating growth is se
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
