Charles G. Sibley
Bio: Charles G. Sibley is an academic researcher from American Museum of Natural History. The author has contributed to research in topics: Passerine & DNA–DNA hybridization. The author has an hindex of 34, co-authored 83 publications receiving 8414 citations. Previous affiliations of Charles G. Sibley include San Francisco State University & Cornell University.
Papers published on a yearly basis
01 Jan 1990
TL;DR: This supplement to Sibley and Monroe's "Distribution and Taxonomy of Birds of the World" presents changes in systematics that they have noted through May 1992, including a change in the total number of living species to 9702.
Abstract: The classification numbering system species accounts taxanomic approach species-group English names.
23 Jan 1991
TL;DR: Part 1: a brief history structure and properties of DNA gene structure and function genetic regulation DNA reassociation and thermal stability the sequence organization of the genome
Abstract: Part 1: a brief history structure and properties of DNA gene structure and function genetic regulation DNA reassociation and thermal stability the sequence organization of the genome the families of repeated DNA homology comparative DNA-DNA studies materials and methods data analysis tempo of evolution demographic factors and rates of DNA evolution a chronological survey of the classification of birds principles and methods of classification classification of birds based on DNA-DNA hybridization melting curves and dendrograms. Part 2: accounts of the groups of birds.
TL;DR: This work has compared the single-copy nuclear DNA sequences of the hominoid genera using DNA-DNA hybridization to produce a complete matrix of delta T50H values and shows that the branching sequence of the lineages was: Old World monkeys, gibbons, Orangutan, Gorilla, chimpanzees, and Man.
Abstract: The living hominoid primates are Man, the chimpanzees, the Gorilla, the Orangutan, and the gibbons. The cercopithecoids (Old World monkeys) are the sister group of the hominoids. The composition of the Hominoidea is not in dispute, but a consensus has not yet been reached concerning the phylogenetic branching pattern and the dating of divergence nodes. We have compared the single-copy nuclear DNA sequences of the hominoid genera using DNA-DNA hybridization to produce a complete matrix of delta T50H values. The data show that the branching sequence of the lineages, from oldest to most recent, was: Old World monkeys, gibbons, Orangutan, Gorilla, chimpanzees, and Man. The calibration of the delta T50H scale in absolute time needs further refinement, but the ranges of our estimates of the datings of the divergence nodes are: Cercopithecoidea, 27-33 million years ago (MYA); gibbons, 18-22 MYA; Orangutan, 13-16 MYA; Gorilla, 8-10 MYA; and chimpanzees-Man, 6.3-7.7 MYA.
TL;DR: In this article, the authors reported molecular estimates of divergence times that average about 50-90% earlier than those predicted by the classical hypothesis, and showed that the timing of these divergences coincides with the Mesozoic fragmentation of emergent land areas, suggesting that continental breakup may have been an important mechanism in the ordinal diversification of birds and mammals.
Abstract: THE classical hypothesis for the diversification of birds and mammals proposes that most of the orders diverged rapidly in adaptive radiations after the Cretaceous/Tertiary (K/T) extinction event 65 million years ago1–3. Evidence is provided by the near-absence of fossils representing modern orders before the K/T boundary4,5. However, fossil-based estimates of divergence time are known to be conservative because of sampling biases6, and some molecular/time estimates point to earlier divergences among orders7–10. In an attempt to resolve this controversy, we have estimated times of divergence among avian and mammalian orders with a comprehensive set of genes that exhibit a constant rate of substitution. Here we report molecular estimates of divergence times that average about 50–90% earlier than those predicted by the classical hypothesis, and show that the timing of these divergences coincides with the Mesozoic fragmentation of emergent land areas. This suggests that continental breakup may have been an important mechanism in the ordinal diversification of birds and mammals.
TL;DR: A ‘silver bullet’ strategy on the part of conservation planners, focusing on ‘biodiversity hotspots’ where exceptional concentrations of endemic species are undergoing exceptional loss of habitat, is proposed.
Abstract: Conservationists are far from able to assist all species under threat, if only for lack of funding. This places a premium on priorities: how can we support the most species at the least cost? One way is to identify 'biodiversity hotspots' where exceptional concentrations of endemic species are undergoing exceptional loss of habitat. As many as 44% of all species of vascular plants and 35% of all species in four vertebrate groups are confined to 25 hotspots comprising only 1.4% of the land surface of the Earth. This opens the way for a 'silver bullet' strategy on the part of conservation planners, focusing on these hotspots in proportion to their share of the world's species at risk.
TL;DR: A new statistical method for estimating divergence dates of species from DNA sequence data by a molecular clock approach is developed, and this dating may pose a problem for the widely believed hypothesis that the bipedal creatureAustralopithecus afarensis, which lived some 3.7 million years ago, was ancestral to man and evolved after the human-ape splitting.
Abstract: A new statistical method for estimating divergence dates of species from DNA sequence data by a molecular clock approach is developed. This method takes into account effectively the information contained in a set of DNA sequence data. The molecular clock of mitochondrial DNA (mtDNA) was calibrated by setting the date of divergence between primates and ungulates at the Cretaceous-Tertiary boundary (65 million years ago), when the extinction of dinosaurs occurred. A generalized least-squares method was applied in fitting a model to mtDNA sequence data, and the clock gave dates of 92.3 +/- 11.7, 13.3 +/- 1.5, 10.9 +/- 1.2, 3.7 +/- 0.6, and 2.7 +/- 0.6 million years ago (where the second of each pair of numbers is the standard deviation) for the separation of mouse, gibbon, orangutan, gorilla, and chimpanzee, respectively, from the line leading to humans. Although there is some uncertainty in the clock, this dating may pose a problem for the widely believed hypothesis that the pipedal creature Australopithecus afarensis, which lived some 3.7 million years ago at Laetoli in Tanzania and at Hadar in Ethiopia, was ancestral to man and evolved after the human-ape splitting. Another likelier possibility is that mtDNA was transferred through hybridization between a proto-human and a proto-chimpanzee after the former had developed bipedalism.
TL;DR: The number of prokaryotes and the total amount of their cellular carbon on earth are estimated to be 4-6 x 10(30) cells and 350-550 Pg of C (1 Pg = 10(15) g), respectively, which is 60-100% of the estimated total carbon in plants.
Abstract: The number of prokaryotes and the total amount of their cellular carbon on earth are estimated to be 4-6 3 10 30 cells and 350-550 Pg of C (1 Pg 5 10 15 g), respectively. Thus, the total amount of prokaryotic carbon is 60-100% of the estimated total carbon in plants, and inclusion of prokaryotic carbon in global models will almost double estimates of the amount of carbon stored in living organisms. In addition, the earth's prokaryotes contain 85-130 Pg of N and 9-14 Pg of P, or about 10-fold more of these nutrients than do plants, and represent the largest pool of these nutrients in living organisms. Most of the earth's prokaryotes occur in the open ocean, in soil, and in oceanic and terrestrial subsurfaces, where the numbers of cells are 1.2 3 10 29 , 2.6 3 10 29 , 3.5 3 10 30 , and 0.25-2.5 3 10 30 , respectively. The numbers of het- erotrophic prokaryotes in the upper 200 m of the open ocean, the ocean below 200 m, and soil are consistent with average turnover times of 6-25 days, 0.8 yr, and 2.5 yr, respectively. Although subject to a great deal of uncertainty, the estimate for the average turnover time of prokaryotes in the subsurface is on the order of 1-2 3 10 3 yr. The cellular production rate for all prokaryotes on earth is estimated at 1.7 3 10 30 cellsyyr and is highest in the open ocean. The large population size and rapid growth of prokaryotes provides an enormous capacity for genetic diversity. Although invisible to the naked eye, prokaryotes are an essential component of the earth's biota. They catalyze unique and indispensable transformations in the biogeochemical cy- cles of the biosphere, produce important components of the earth's atmosphere, and represent a large portion of life's genetic diversity. Although the abundance of prokaryotes has been estimated indirectly (1, 2), the actual number of pro- karyotes and the total amount of their cellular carbon on earth have never been directly assessed. Presumably, prokaryotes' very ubiquity has discouraged investigators, because an esti- mation of the number of prokaryotes would seem to require endless cataloging of numerous habitats. To estimate the number and total carbon of prokaryotes on earth, several representative habitats were first examined. This analysis indicated that most of the prokaryotes reside in three large habitats: seawater, soil, and the sedimentysoil subsur- face. Although many other habitats contain dense populations, their numerical contribution to the total number of pro- karyotes is small. Thus, evaluating the total number and total carbon of prokaryotes on earth becomes a solvable problem. Aquatic Environments. Numerous estimates of cell density, volume, and carbon indicate that prokaryotes are ubiquitous in marine and fresh water (e.g., 3-5). Although a large range of cellular densities has been reported (10 4 -10 7 cellsyml), the
TL;DR: The combination of these phylogenies with powerful new statistical approaches for the analysis of biological evolution is challenging widely held beliefs about the history and evolution of life on Earth.
Abstract: Phylogenetic trees describe the pattern of descent amongst a group of species. With the rapid accumulation of DNA sequence data, more and more phylogenies are being constructed based upon sequence comparisons. The combination of these phylogenies with powerful new statistical approaches for the analysis of biological evolution is challenging widely held beliefs about the history and evolution of life on Earth.
TL;DR: Analysis of variance of log K for all 121 traits indicated that behavioral traits exhibit lower signal than body size, morphological, life-history, or physiological traits, and this work presents new methods for continuous-valued characters that can be implemented with either phylogenetically independent contrasts or generalized least-squares models.
Abstract: The primary rationale for the use of phylogenetically based statistical methods is that phylogenetic signal, the tendency for related species to resemble each other, is ubiquitous. Whether this assertion is true for a given trait in a given lineage is an empirical question, but general tools for detecting and quantifying phylogenetic signal are inadequately developed. We present new methods for continuous-valued characters that can be implemented with either phylogenetically independent contrasts or generalized least-squares models. First, a simple randomization procedure allows one to test the null hypothesis of no pattern of similarity among relatives. The test demonstrates correct Type I error rate at a nominal α = 0.05 and good power (0.8) for simulated datasets with 20 or more species. Second, we derive a descriptive statistic, K, which allows valid comparisons of the amount of phylogenetic signal across traits and trees. Third, we provide two biologically motivated branch-length transformat...