台灣產東方果實蠅 (雙翅目：果實蠅科) 之形態多樣性及表型可塑性

在許多生物中，都可發現形態的多樣性，此現象可因基因或環境的差異而產生，然而，這兩者常常在同一時間作用於同一個體。表型可塑性 (phenotypic plasticity) 即代表僅環境因子所造成的形態變異，此一環境依變的現象常常在演化過程中扮演重要的角色，也因此，在某些時候，此現象有助於研究者更貼近分類上所面臨的困難。在此研究中，我們檢視臺灣的野外東方果實蠅 (Bactrocera dorsalis) 族群的形態變異，包括後頭區的黑色色斑、胸部板塊上的黃褐色斑、翅基後肩剛毛的位置及腹部背板上的黑色色斑，經分析後發現，利用這些變異特徵，樣本存在季節性的差異，於是，我們進一步假設東方果實蠅的這些特徵會受其中一項環境因子｢溫度｣所影響。經由在六個不同溫度下飼養的結果發現，在中胸背板、後小楯板、中背板及腹部背板上的黑色斑紋會明顯受蟲體生長環境的溫度所影響，而影響的趨勢與大部分其他昆蟲雷同：高溫會驅使較少的黑色斑紋表現，而低溫則會讓蟲體表現較多的黑色斑紋，而且，除了花蓮以外，臺北、臺中、屏東及蘭嶼皆發現這些色斑的比例在夏天與冬天有著顯著性的差異。此外，在實驗室內飼養的結果也顯示，在不同的溫度下生長的東方果實蠅，其翅膀的形狀有著漸進式的改變，表示溫度亦會影響蟲體的翅形，然而，除了臺中與蘭嶼外，大部分的野外樣本並無夏天與冬天的差異。相較於上述的兩個主要特徵，位於脛節上的短錐形感覺毛數量在不同溫度飼養及不同季節的蟲體上，並無明顯差異。根據我們的實驗結果，斑紋與翅形皆受溫度所影響，但是，這兩個具表形可塑性的特徵卻是長期以來用於區分東方果實蠅種群內幾個多食性、具高度經濟重要性物種的分類特徵，所以，我們認為，以這類特徵做為分類依據並不適當。此外，類似的情形是否也存在東方果實蠅種群的其他物種當中，以及表型可塑性在這些昆蟲的快速分化中所扮演的意義，均須要更多其他物種的研究結果來討論。

關鍵字

東方果實蠅；表型可塑性；溫度；黑化；翅形；形態測量

並列摘要

Morphological polymorphism could be induced by either genetic or environmental variations. However, they usually worked together at the same time. The phenomenon of environmental effects on morphological change is called phenotypic plasticity, which plays an important role in evolution. In some cases, this phenomenon could help researchers exploring taxonomic problem in more detail. In current study, we investigated the morphological polymorphism on Bactrocera dorsalis in Taiwan including the color pattern on occiput, thoracic brown patterns, the position of intra-alar bristles, and the black patterns on the abdominal tergites. These color patterns showed seasonal variations in the wild-type flies. Therefore, one of the environmental factors, temperature, was selected for further analysis. In the laboratory populations, we found that the temperature-dependent variations of melanism on scutum, subscutellum, mediotergite, and abdomen do exist in oriental fruit flies (B. dorsalis). The reaction norm that higher melanism happened under lower temperature was similar to those in other insects. Besides, temperature also affected wing shape in rearing populations according to our geometric morphometric results, while no obvious pattern was found in the field samples. Contrast to those characters mentioned above, the sensilla numbers on tibiae have no difference under different seasons or rearing temperature. According to the results, we suggest that both the color patterns and wing shape of the fly could be affected by temperature. However, most of them were considered diagnostic taxonomic morphological characters used to divide different species in B. dorsalis complex. Therefore, further studies on environmentally-induced morphological changes in other species in dorsalis complex need to be conducted, which might provide another explanation on these phytophagous sibling species with high morphological similarity.

並列關鍵字

Bactrocera dorsalis ； phenotypic plasticity ； temperature ； melanism ； wing shape ； geometric morphometrics

參考文獻

Hsu J-C, Liu P-F, Hertlein M, Mau RFL, Feng H-T. 2010. Greenhouse and field evaluation of a new male annihilation technique (MAT) product, SPLAT-MAT spinosad ME (TM), for the control of oriental fruit flies (Diptera: Tephritidae) in Taiwan. Formosan Entomol 30: 87-100.

Aketarawong N, Bonizzoni M, Thanaphum S, Gomulski LM, Gasperi G et al. 2007. Inferences on the population structure and colonization process of the invasive oriental fruit fly, Bactrocera dorsalis (Hendel). Mol Ecol 16: 3522-3532.

Ansari SA, Knowles K, Zbikowski R. 2008. Insectlike flapping wings in the hover part 2: effect of wing geometry. Journal of Aircraft 45: 1976-1990.

Barnes AI, Siva-Jothy MT. 2000. Density-dependent prophylaxis in the mealworm beetle Tenebrio molitor L. (Coleoptera: Tenebrionidae): cuticular melanization is an indicator of investment in immunity. Proc R Soc Lond B Biol Sci 267: 177-182.

Berry RJ. 1990. Industrial melanism and peppered moths (Biston betularia (L.)). Biol J Linn Soc 39: 301-322.

國際替代計量

台灣產東方果實蠅 (雙翅目：果實蠅科) 之形態多樣性及表型可塑性

全文下載

主題瀏覽