色彩斑紋特徵是親緣關係重建上的雜訊或是可靠的訊息？

Abstract

涉及強烈色彩對比的顏色特徵，如擬態或警戒，相對於非顏色特徵而言，由於牽涉到生物整體的色彩斑紋呈現，通常在親緣關係的重建上被視為較不獨立或較受限制的特徵，認為會造成與其他特徵的衝突。本論文取樣六十筆近期發表之以形態特徵為依據的親緣關係文獻，以先驗性假設進行兩次文獻分組策略，再對文獻中所使用的特徵區分為色彩斑紋組與非色彩斑紋組，進行加權測試，以探討色彩斑紋特徵在親緣關係重建上所扮演的角色。我們發現無涉警戒或擬態的色彩斑紋特徵，即使為隱蔽色或逢機分布的特徵，亦可能誤導親緣關係之重建；我們也發現具有警戒色的生物其色彩斑紋特徵近似於隨機地在演化樹上出現，因此其資訊往往與非色彩斑紋特徵相衝突；至於涉及擬態類群的顏色斑紋特徵在親緣關係重建上之表現，則不見得如前人研究結果所述的不佳，其原因可能是用以重建親緣關係的顏色特徵事實上並未參與形成擬態或警戒性。總結而言，我們建議在使用形態特徵進行親緣關係研究時，不要預先對顏色斑紋特徵存有偏見；若要探討某些特徵的影響，則應將矩陣區分為兩個互相獨立的部份，再以本研究之方法進行評估；或另以分子資料做出親緣關係樹後，再將形態資料映象到樹形圖上進行特徵分布之討論。Colour characters involved in strongly conserved patterns, such as aposematism or mimicry, are considered to be more phylogenetically constrained due to their direct relationship with the whole colour pattern which may show strongly structured evolution possibly causing phylogenetic opinions in conflict with the signal of other morphological characters. We investigated the impact of colour/pattern characters on phylogenetic reconstruction using 60 recently published datasets and performed 2 dataset partitioning strategies based on a priori postulation. We found that colour/pattern characters not involving mimicry or aposematism, even cryptic or randomly distributed characters, may also mislead phylogenetic reconstruction. The colour/pattern characters involved in aposematism tend to be distributed randomly on phylogeny so that the information being provided may cause conflicting pattern with that based on non-colour/pattern characters. The mimetic colour/pattern characters are not that bad in phylogenetic reconstruction as previous studies suggested because the colour/pattern characters brought into phylogenetic analysis may actually not participate in any aposematism or mimicry phenomenon. In conclusion, we suggest that it is unnecessarily to give peculiar judgments to C/P characters before reconstruct phylogenetic trees.