由貝類觀察表型變化的環境適應作用

文蛤是一種固著性生物，一個群體內便有多樣的表型變化。本研究探討這非基因的機制在這受環境變遷威脅下的世界中之重要性，這項是根據對文蛤的觀察。第一個要驗證的假說是適應度取決於表型特徵與環境因素的相互作用。這項假說的驗證乃依據大量觀察的結果，文蛤樣品依色澤（coloration）、圖案（patterning）及結晶組織分成三種表型。適應度由尺寸及腹緣（ventral margin）潔白度（whiteness）來判定。另外隨著表形而變的光澤、抗破裂強度、存活率、及適應機制都有重要意涵。淡顏色的表型A之平均尺寸最大，殼變厚經常發生在此表型中。有輻射狀條紋圖案的表型B之存活率最低。深顏色的表型C之光澤及抗破裂強度最高。第二個假說是適應度的差異主要由結晶組織的不同而來，外在的特徵會影響碳酸鈣的結晶組織，這是因為殼皮（periostracum）作為結晶的基板（matrix）。結晶組織也與發育可塑性有關，表型影響適應度的相關資訊可用來選擇環境監控的指標。保持表型多樣性可以增加群體永續性及對環境變化的抵抗力。

關鍵字

表型變化；適應度；結晶組織；發育可塑性

並列摘要

Hard clams, an immobile sessile animal, display great phenotypic variation in a population. This work studies the significance of this non-genetic mechanism in a world threaten by environmental changes through observation on hard clams. The first hypothesis to be verified is that fitness is dependent on the interaction between phenotypic traits and environmental factors. A large number of clam samples have been examined for the verification. Clams can be divided into three phenotypes based on coloration, pigmentation patterning, and organization of crystals. Fitness is evaluated by size and the whiteness at the ventral margin. Other phenotype-dependent traits like glossiness, fracture resistance, survival rate, and developmental plasticity also provide important information. In average, light-colored phenotype A has the largest size. Shell thickening often occurs in phenotype A. Stripe-decorated phenotype B has the lowest survival rate. Dark-colored phenotype C has the highest glossiness and fracture resistance. The second hypothesis is that the variation of fitness is mainly caused the difference in crystal organization. External traits affect the crystal organization since the periostracum serves as a matrix for crystallization. Crystal organization is also related to developmental plasticity. Information about phenotype-dependent fitness can be used in selecting indicators for monitoring environmental effects. Maintaining phenotypic diversity can improve community sustainability and tolerance to changing environment.

並列關鍵字

phenotypic variation ； fitness ； crystal organization ； developmental plasticity

參考文獻

[19] An-Chin Lee, The Effect of Temperature and Components of Artificial Seawater on Digging Ability of Hard Clam (Meretrix lusoria), J. Fish. Soc. Taiwan, 31(4): (2004), 251-262.

[2] Colin Brownlee, Alison R Taylor, Algal Calcification and Silification, ENCYCLOPEDIA OF LIFE SCIENCES, (2002).

[3] T.A. McConnaughey, J.F. Whelan, Calcification generates protons for nutrient and bicarbonate uptake, Earth-Science Reviews 42 (1997), 95-117.

[4] Allegra M. Small, Walter H. Adey, Reef corals, zooxanthellae and free-living algae: a microcosm study that demonstrates synergy between calcification and primary production, Ecological Engineering 16 (2001), 443–457.

[5] Bambach, R.K.; Knoll, A.H. & Wang, S.C., Origination, extinction, and mass depletions of marine diversity, Paleobiology (2004) 30(4): 522–542, doi:10.1666/0094-8373(2004)030 <0522:OEAMDO>

國際替代計量

由貝類觀察表型變化的環境適應作用

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