Ancestral state reconstruction of body size in the Caniformia (Carnivora, Mammalia): The effects of incorporating data from the fossil record
Ancestral state reconstruction of body size in the Caniformia (Carnivora, Mammalia): The effects of incorporating data from the fossil record
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DOI：
10.1080/10635150500541698
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发表时间：
2006-04-01
影响因子：
6.5
通讯作者：
Flynn, JJ
中科院分区：
文献类型：
--
作者：
Finarelli, JA;Flynn, JJ
最近的哺乳动物食肉目的分子系统发育暗示大的身体尺寸作为祖先条件的犬科亚支Arctoidea使用物种平均身体尺寸之间的分布生活类群。“现存的类群”的方法，如这些折扣的特征状态观察化石成员的生活分支，并完全忽略了数据从灭绝的血统。为了更严格地重建犬形目内祖先形式的身体大小，收集了149个现存和367个灭绝分类群的身体大小和首次出现的数据。身体大小重建四个祖先节点使用加权平方变化简约的对数转换的体重数据。基于现存分类群的重建，对于犬形目和熊总科最后的共同祖先来说，更倾向于大型体型（大约10到50公斤）。与此相反，结合化石数据的重建支持这些分支的祖先体型较小（< 5公斤）。当与化石数据相关的时间信息被丢弃时，身体大小重建变得模糊不清，这表明将化石分类群的特征状态和时间信息结合起来明确支持一个小的祖先身体大小，从而伪造了仅来自现存分类群的假设。犬形目，Arctoidea和Musteloidea的身体大小重建不敏感的潜在错误引入的不确定性的位置灭绝的谱系相对于分子拓扑结构，或失踪的身体大小数据灭绝的成员的整个主要分支（水生鳍足）。将化石记录中的特征状态观察和时间信息转化为假设检验，对重建祖先特征的能力有重大影响，并限制了特征进化的潜在假设范围。这里的化石数据提供的证据，可靠地记录的趋势，增加和减少身体的大小在几个犬形分支。更一般地说，在这样的分析中包括化石结合了方向趋势的证据，从而产生更可靠的祖先特征状态重建。
A recent molecular phylogeny of the mammalian order Carnivora implied large body size as the ancestral condition for the caniform subclade Arctoidea using the distribution of species mean body sizes among living taxa. "Extant taxa-only" approaches such as these discount character state observations for fossil members of living clades and completely ignore data from extinct lineages. To more rigorously reconstruct body sizes of ancestral forms within the Caniformia, body size and first appearance data were collected for 149 extant and 367 extinct taxa. Body sizes were reconstructed for four ancestral nodes using weighted squared-change parsimony on log-transformed body mass data. Reconstructions based on extant taxa alone favored large body sizes (on the order of 10 to 50 kg) for the last common ancestors of both the Caniformia and Arctoidea. In contrast, reconstructions incorporating fossil data support small body sizes (< 5 kg) for the ancestors of those clades. When the temporal information associated with fossil data was discarded, body size reconstructions became ambiguous, demonstrating that incorporating both character state and temporal information from fossil taxa unambiguously supports a small ancestral body size, thereby falsifying hypotheses derived from extant taxa alone. Body size reconstructions for Caniformia, Arctoidea, and Musteloidea were not sensitive to potential errors introduced by uncertainty in the position of extinct lineages relative to the molecular topology, or to missing body size data for extinct members of an entire major clade (the aquatic Pinnipedia). Incorporating character state observations and temporal information from the fossil record into hypothesis testing has a significant impact on the ability to reconstruct ancestral characters and constrains the range of potential hypotheses of character evolution. Fossil data here provide the evidence to reliably document trends of both increasing and decreasing body size in several caniform clades. More generally, including fossils in such analyses incorporates evidence of directional trends, thereby yielding more reliable ancestral character state reconstructions.