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Early Radiation (early + radiation)
Selected AbstractsA new tooth-plated lungfish from the Middle Devonian of Yunnan, China, and its phylogenetic relationshipsACTA ZOOLOGICA, Issue 2009Tuo Qiao Abstract A new genus and species of tooth-plated lungfish, Sinodipterus beibei gen. et sp. nov., is described from the Qujing Formation (Middle Devonian, late Eifelian) of Zhaotong, Yunnan, China. The new form resembles Dipterus in the skull table, but differs in its tooth-plate: cosmine-like tissue absent near the midline, tooth rows fewer in number (7 to 8) and less divergent radiating, and no reparative dentine layers. Phylogenetic analysis of Devonian lungfish based on a dataset of 150 characters and 33 taxa indicates that the new taxon is more crownward than Dipterus and the clade comprising Adololopas, Sorbitorhynchus and Pillararhynchus. Our results agree broadly with previous cladistic solutions. Diabolepis is placed as a sister group to all other Devonian lungfish. The species referred to Chirodipterus fail to form a monophyletic group. The result shows a large number of convergences corresponding to early radiation of lungfish compressed in time. [source] Patterns of speciation in endemic Mexican Goodeid fish: sexual conflict or early radiation?JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2005M. G. RITCHIE Abstract Currently there is much interest in the potential for sexual selection or conflict to drive speciation. Theory proposes that speciation will be accelerated where sexual conflict is strong, particularly if females are ahead because mate choice will accentuate divergence by limiting gene flow. The Goodeinae are a monophyletic group of endemic Mexican fishes with an origin at least as old as the Miocene. Sexual selection is important in the Goodeinae and there is substantial interspecific variability in body morphology, which influences mate choice, allowing inference of the importance of female mate choice. We therefore used this group to test the relationship between sexual dimorphism and speciation rate. We quantified interspecific variation in sexual dimorphism amongst 25 species using a multivariate measure of total morphological differentiation between the sexes that accurately reflects sexual dimorphism driven by female mate choice and also used a mtDNA-based phylogeny to examine speciation rates. Comparative analyses failed to support a significant association between sexual dimorphism and speciation rate. In addition, variation in the time course of speciation throughout the whole clade was also examined using a similar tree containing 34 extant species. A constant rates model for the growth of this clade was rejected, but analyses instead indicated a decline in the rate of speciation over time. These results support the hypothesis of an early expansion of the group, perhaps due to an early radiation influenced by the key innovation of live bearing, or the prevalence of Miocene volcanism. In general, support for the role of sexual selection in generating patterns of speciation is proving equivocal and we argue that vicariance biogeography and adaptive radiations remain the most likely determinants of major patterns of diversification of continental organisms. [source] First partial face and upper dentition of the Middle Miocene hominoid Dryopithecus fontani from Abocador de Can Mata (Vallès-Penedès Basin, Catalonia, NE Spain): Taxonomic and phylogenetic implicationsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Salvador Moyà-Solà Abstract A well-preserved 11.8-million-years-old lower face attributed to the seminal taxon Dryopithecus fontani (Primates, Hominidae) from the Catalan site ACM/C3-Ae of the Hostalets de Pierola area (Vallès-Penedès Basin, Catalonia, NE Spain) is described. The new data indicate that D. fontani is distinct at the genus level from Late Miocene European taxa previously attributed to Dryopithecus, which are here reassigned to Hispanopithecus. The new facial specimen also suggests that D. fontani and the Middle Miocene Pierolapithecus catalaunicus are not synonymous. Anatomical and morphometric analyses further indicate that the new specimen shows a combination of lower facial features,hitherto unknown in Miocene hominoids,that resembles the facial pattern of Gorilla, thus providing the first nondental evidence of gorilla-like lower facial morphology in the fossil record. Considering the current evidence, the gorilla-like facial pattern of D. fontani is inferred to be derived relative to previously known stem hominids, and might indicate that this taxon is either an early member of the Homininae or, alternatively, a stem hominid convergent with the lower facial pattern of Gorilla. The biogeographic implications of both alternatives are discussed. This new finding in the Hostalets de Pierola section reinforces the importance of this area for understanding the elusive question of the Middle Miocene origin and early radiation of great apes. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Phylogeny of the Eucoilinae (Hymenoptera: Cynipoidea: Figitidae)CLADISTICS, Issue 2 2002F.M. Fontal-Cazalla The Eucoilinae are a diverse and important group of parasitoids of Diptera, particularly in the tropics, but they are poorly known systematically and their generic classification is partly chaotic. Here, we present the first comprehensive cladistic analysis of higher eucoiline relationships. The analysis is based on 148 skeletal characters of adults documented in more than 1100 digital images available in an Internet-accessible database. The characters were coded for 45 taxa representing 35 eucoiline genera, spanning the entire diversity of the group, and 7 outgroup genera. Relationships were partly difficult to resolve and parsimony analysis under implied weights performed considerably better than analysis under uniform weights. The results support the monophyly of the Eucoilinae and show that eucoilines are most closely related to the figitid subfamilies Emargininae and Pycnostigminae, but are ambiguous concerning the exact relationships among these three lineages. Of the 6 eucoiline genus groups recognized by Nordlander in 1982 (Entomol. Scand. 13, 269,292), only 2 are supported as monophyletic: the Trybliographa and Kleidotoma groups. The Gronotoma group is a paraphyletic assemblage of two different basal clades of eucoilines. The Rhoptromeris group is unnatural and only the 2 core genera, Rhoptromeris and Trichoplasta, form a monophyletic lineage. The data are ambiguous concerning the Ganaspis group, which appears to be paraphyletic, and the Chrestosema group, which may be a good clade. Based on the results we propose a modified system of informal genus groups in the Eucoilinae and discuss putative synapomorphies supporting each genus group. The proposed relationships imply that the first eucoilines were parasitoids of leaf-mining agromyzids. The earliest split in the group was apparently between an Afrotropical and a Neotropical lineage, and much of the early radiation of the group occurred in these regions, particularly in the Neotropics. [source] | ||||||||||