Detail A Cambrian Peak in Morphological Variation Within Trilobite Species   Oleh:  Webster, Mark Jenis: Article from Bulletin/Magazine Dalam koleksi: SCIENCE (keterangan: ada di Proquest) vol. 317 no. 5837 (Jul. 2007), page 499. Topik: Reports Ketersediaan Perpustakaan FK Nomor Panggil: S01.K.2007.07 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel Morphological variation within species is a raw material subject to natural selection. However, temporal change in morphological diversity has usually been studied in terms of variation among rather than within species. The distribution of polymorphic traits in cladistic character-taxon matrices reveals that the frequency and extent of morphological variation in 982 trilobite species are greatest early in the evolution of the group: Stratigraphically old and/or phylogenetically basal taxa are significantly more variable than younger and/or more derived taxa. Through its influence on evolutionary tempo, high intraspecific variation may have played a major role in the pronounced Cambrian diversification of trilobites. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

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