Stratophenetic tracing of phylogeny using SIMCA pattern recognition technique: a case study of the late Neogene planktic foraminifera Globoconella clade
Stratophenetic tracing of phylogeny using SIMCA pattern recognition technique: a case study of the late Neogene planktic foraminifera Globoconella clade
复制标题
使用 SIMCA 模式识别技术进行系统发育平流追踪：以新近纪晚期浮游有孔虫 Globoconella 分支为例
作者：
K. Wei
深海钻探项目588站点上更新世gloorotalia (Globoconella) puncticulata-inflata进化支浮游有孔虫序列，时间为4.36 ~ 0.05 Ma，记录了G. inflata谱系从原始G. puncticulata谱系的分支历史。这种分化的层次性和巨大的形态变异引起了人们对这一分支的分类学和系统发育的不同看法。采用模式识别技术——类相似物的软独立建模（SIMCA）作为一种客观定量的层析方法来重建系统发育历史。在2.76 Ma的地层水平上鉴定出了2种典型的标本，即点棘棘藓和膨胀棘藓。利用SIMCA建立主成分模型，表征两种形态的形态计量模式。根据模型对下一层和上一层的Globoconella标本进行了评价，并将其划分为两种形态之一。然后，新分类的标本分别用于建立新的模型，以进一步追踪下部和上部剖面的谱系。通过地层间隔的这种训练和分类程序的进展导致了两个谱系的进化模式的重建。进化发生在3.5 Ma左右产生了G. inflata后代系。这两个共存的物种，即膨胀和点棘棘，仅在大小上有所不同，在分化之初，它们在大多数性状上表现出相似性。后来，其他的性格开始以不同的速度分化。在上新世晚期，浮游和底栖有孔虫的δ18O值梯度呈持续上升趋势。在同一时间内，从斑马鱼到膨胀鱼的演替与地表水温度的垂直分层逐渐增加有关。2.35 Ma时，温度梯度进一步升高，对应于北半球大范围冰期的开始。
The Plio-Pleistocene planktic foraminiferal sequence of the Globorotalia (Globoconella) puncticulata-inflata clade in Deep Sea Drilling Project Site 588, dated at 4.36 Ma to 0.05 Ma, records the branching history of the G. inflata lineage from the ancestral G. puncticulata lineage. The gradational nature of the divergence and the enormous morphological variability inherent in the G. inflata lineage have elicited different views on taxonomy and phylogeny of this clade. A pattern recognition technique, soft independent modeling of class analog (SIMCA), was used as an objective quantitative stratophenetic methodology to reconstruct the phylogenetic history. Typical specimens of two species, G. puncticulata and G. inflata, were identified from a stratigraphic level dated at 2.76 Ma. Principal component models were built to characterize the morphometric patterns of the two morphotypes using SIMCA. The Globoconella specimens of the next lower and higher adjacent stratigraphic levels were evaluated against the models and classified into one of the two morphotypes. The newly classified specimens were then used to build new models for further tracing of lineages in lower and upper sections, respectively. Progression of such training and classification procedures through stratigraphic intervals resulted in a reconstruction of the evolutionary patterns of the two lineages. Cladogenesis gave rise to the descendant lineage, G. inflata, at about 3.5 Ma. The two co-existing species, G. inflata and G. puncticulata, differ only in size and show similarity in most characters at the beginning of their divergence. Other characters began to diverge later, at various rates. The gradients between planktic and benthic foraminiferal δ18O values show a continuous increase during the late Pliocene. The succession from G. puncticulata to G. inflata during the same time correlates with the progressively increased vertical stratification in temperature of surface waters. Globorotalia puncticulata became extinct at 2.35 Ma when the temperature gradient further increased, corresponding to the onset of extensive glaciation in the Northern Hemisphere.