A number of lines of evidence suggest that the rate of molecular evolution in birds is slower than in other vertebrates. This hypothesis was tested by measuring the extent of amino-acid sequence divergence in albumin among species of parrots by means of microcomplement fixation. This group was chosen because its modern distribution is strongly suggestive of a Gondwanan origin. The results show that the intercontinental albumin distances are well below those expected for a Gondwanan group. These data are in accord with the hypothesis that birds have a slower rate of molecular evolution, although other explanations are possible.
SummarySummaryChristidis, L. (1987). Phylogeny and systematics of estrildine finches and their relationships to other seed-eating passerines. Emu 87, 119–123.A cladistic analysis of chromosomal and electrophoretic data provided the basis for a phylogeny and revision of estrildine finches. The results indicate that estrildines are best treated as a subfamily, Estrildinae, within the Passeridae. The Estrildinae themselves comprise three natural tribal assemblages: Poephilini (grassfinches), Lonchurini (mannikins) and Estrildini (waxbills). Of these, the Lonchurini appear to be the most recently evolved. The Red-browed Finch Aegintha temporalis and Plum-headed Finch Aidemosyne modesta are each other's closest relatives and, together with the Star Finch Neochima ruficauda and Crimson Finch N. phaeton, constitute a single genus. The currently recognised genera, Poephila, Emblema and Lonchura are split into several smaller genera.
Taxa that are known as great speciators are characterised by a rare combination of a potential to disperse coupled with a tendency not to, because extensive dispersal leads to gene fl ow counteracting differentiation, and too little dispersal leads to an inability to colonise new areas. Here we investigate the phylogenetic history of the genus Aerodramus, a group of echolocating swiftlets that has diversifi ed throughout the Indo-Pacifi c region, to gauge the level of differentiation and ascertain if traditional taxonomy provides an accurate assessment of species diversity, and fi nd several phylogenetic relationships that challenge traditional taxonomy, especially within the A. vanikorensis species complex. We also suggest that the genus may be considered a great speciator, which has undergone a recent rapid radiation involving the colonisation of most islands in the Indian and Pacifi c oceans. * corresponding author)
Abstract In a recently published paper, Taylor and colleagues discussed different approaches and interpretations of mammalian taxonomy and their bearing on more general issues such as conservation and evolutionary biology. We fully endorse the fundamental importance of taxonomy and its being grounded on scientific principles. However, we also deplore a lack of awareness in the literature of the fact that taxonomy is a twofold enterprise that encompasses not only (i) the scientific description and quantitative analysis of biodiversity but also (ii) an executive decision as to how the results of (i) are translated into names. This has serious ramifications for the conservation of our planet’s dwindling biodiversity and when taxonomic names are used as raw data for ecological and evolutionary analyses.
Abstract Background: Trophic shifts from one dietary niche to another have played major roles in reshaping the evolutionary trajectories of a wide range of vertebrate groups, yet its consequences for morphological disparity and species diversity differs among groups. Methods: Here, we use phylogenetic comparative methods to examine whether the evolution of nectarivory and other trophic shifts have driven predictable evolutionary pathways in Australasian psittaculid parrots in terms of ecological traits such as body size, beak shape, and dispersal capacity. Results: Rates of lineage diversification appear to be constant over time and we find no evidence for an ‘early-burst’ scenario of morphological diversification. The best-fitting models indicate that trait evolution in this group is characterized by abrupt phenotypic shifts (evolutionary jumps), with no sign of multiple phenotypic optima correlating with different trophic strategies. Thus, our results point to the existence of weak directional selection and suggest that lineages may be evolving randomly or slowly toward adaptive peaks they have not yet reached. Conclusions: This study adds to a growing body of evidence indicating that the relationship between avian morphology and feeding ecology may be more complex than usually assumed and highlights the importance of adding more flexible models to the macroevolutionary toolbox.
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