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Full-Text Articles in Life Sciences
Origin Of The Eumetazoa: Testing Ecological Predictions Of Molecular Clocks Against The Proterozoic Fossil Record, Kevin J. Peterson, Nicholas J. Butterfield
Origin Of The Eumetazoa: Testing Ecological Predictions Of Molecular Clocks Against The Proterozoic Fossil Record, Kevin J. Peterson, Nicholas J. Butterfield
Dartmouth Scholarship
Molecular clocks have the potential to shed light on the timing of early metazoan divergences, but differing algorithms and calibration points yield conspicuously discordant results. We argue here that competing molecular clock hypotheses should be testable in the fossil record, on the principle that fundamentally new grades of animal organization will have ecosystem-wide impacts. Using a set of seven nuclear-encoded protein sequences, we demonstrate the paraphyly of Porifera and calculate sponge/eumetazoan and cnidarian/bilaterian divergence times by using both distance [minimum evolution (ME)] and maximum likelihood (ML) molecular clocks; ME brackets the appearance of Eumetazoa between 634 and 604 Ma, whereas …
Reductionism And Holism, Chance And Selection, Mechanism And Mind, Ursula Goodenough
Reductionism And Holism, Chance And Selection, Mechanism And Mind, Ursula Goodenough
Biology Faculty Publications & Presentations
Despite its rich and deepening panoply of empirical support, evolutionary theory continues to generate widespread concern. Some of this concern can be attributed to misunderstandings of the original concept, some to unfamiliarity with its current trajectories, and some to strongly held fears that it strips the human of cherished attributes. In this essay I seek to deconstruct such misunderstandings, lift up current concepts of what evolution entails, and address some of the existential issues it generates.
Alfred Russel Wallace: Past And Future [Guest Editorial], Charles H. Smith
Alfred Russel Wallace: Past And Future [Guest Editorial], Charles H. Smith
DLPS Faculty Publications
The naturalist Alfred Russel Wallace (1823–1913) has for many years been standing in the shadow of his more famed co-discoverer of the principle of natural selection, Charles Darwin. Despite outward similarities between the two men’s formulation of the principle, Wallace had fit his appreciation of natural selection into views on evolution that were quite different from Darwin’s. A closer examination of what Wallace had in mind suggests a model of process in which natural selection per se acts as the negative feedback mechanism (actually, a ‘statespace’) in the relation between population and environment, and environmental engagement as made possible by …
Who Believes What? Clearing Up Confusion Over Intelligent Design And Young-Earth Creationism, Marcus R. Ross
Who Believes What? Clearing Up Confusion Over Intelligent Design And Young-Earth Creationism, Marcus R. Ross
Marcus R. Ross
The question of what differentiates young-Earth creationism (YEC) from Intelligent Design (ID) has resulted in inaccurate and confusing terminology, and hinders both understanding and dialogue. Though both YEC and ID groups have drawn distinctions between themselves, previous attempts to classify design-based positions on origins have been unable to adequately resolve their relationships. The Nested Hierarchy of Design, a multiple-character classification system, categorizes teleological positions according to the strength of claims regarding the reality, detectability, source, method, and timing of design, and results in an accurate and robust classification of numerous positions. This method avoids the philosophical and theological pitfalls of …
On The Enigmatic Distribution Of The Honduran Endemic Leptodactylus Silvanimbus (Amphibia: Anura: Lep Todactylidae), W. Ronald Heyer, Rafael O. De Sá, Sarah Muller
On The Enigmatic Distribution Of The Honduran Endemic Leptodactylus Silvanimbus (Amphibia: Anura: Lep Todactylidae), W. Ronald Heyer, Rafael O. De Sá, Sarah Muller
Biology Faculty Publications
Most species of the frog genus Leptodactylus occur in South America, and all authors who have treated the zoogeography of the genus have concluded that it originated somewhere in South America (e.g., Savage 1982). Savage (1982,518) summarized the historical herpetofaunal units of the Neotropics as follows: "All evidence points to an ancient contiguity and essential similarity of a generalized tropical herpetofauna that ranged over tropical North, Middle, and most of South America in Cretaceous-Paleocene times. Descendents of this fauna are represented today by the South and Middle American tracks (Elements). To the north of this fauna ranged a subtropical-temperate Laurasian …