Gradual Versus Punctuated Equilibrium Evolution in the Turkana Basin Molluscs: Evolutionary Events or Biological Invasions?

Bocxlaer, Bert Van; Damme, Dirk Van; Feibel, Craig S.

doi:10.1111/j.1558-5646.2007.00296.x

Cited by 55 publications

(44 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For instance it had been thought that the Turkana Basin in Africa had perfectly-preserved documentation of mollusc evolution over a few hundreds of thousands to a few million years (Williamson 1981). This has been questioned recently by Van Bocxlaer et al (2008) who provide evidence that the Turkana Basin may not be geologically continuous and had, during its formation, been subject to invasions of molluscs from outside, interfering with phylogenetic records.…”

Section: Discussionmentioning

confidence: 93%

Flatfishes, Turtles, and Bolyerine Snakes: Evolution by Small Steps or Large, or Both?

Frazzetta

2011

Evol Biol

View full text Add to dashboard Cite

Step size in evolution is rapidly becoming a major subject of interest to biologists. Traditionally, small changes alone were seen as significant in evolution, and any large differences between an ancestor and its descendant could be explained entirely by the accumulation of many small steps. Whether the evolution of major adaptations is mainly a matter of amassing such small increments of change, or if a significant proportion occurs through the inclusion of one or more large steps, is vital to the understanding of how evolution works. This paper begins by examining four ''classic'' examples of animalsflatfishes, turtles, bolyerine snakes, and gastropod molluscs-each of which has seemed difficult to interpret as resulting from a continuous series of tiny increments. Recently, however, arguments have appeared to contradict those views, and to propose instead that each of these animal groups arose through continuous adaptive modifications. While some of these arguments are more plausible than others, the view of the present author is that in none of them is there convincing evidence to conclude that the groups arose solely through gradual changes. More specifically, there is no basis to reject an evolutionary origin of the major traits in each group that included at least one principal inovation, occurring in a large, discontinuous step, preceded and followed by relatively small, more gradual changes. The broader question of how discontinuous evolution may occur is addressed through several means. These include considerations of epigenetic (sensu Waddington) development, comparative embryology, population genetics, and other approaches. Overall the phenomenon of adaptive accommodation is seen as of major importance, and its implications for ameliorating possible deleterious attributes of novel phenotypes are discussed. In the course of these analyses the doctrine that all adaptive evolution is driven by external environmental change is reviewed. It is suggested that while small adaptive changes are often closely related to shifts in specific environmental facets, the modifications associated with more major adaptations may be less so.

show abstract

Section: Discussionmentioning

confidence: 93%

Flatfishes, Turtles, and Bolyerine Snakes: Evolution by Small Steps or Large, or Both?

Frazzetta

2011

Evol Biol

View full text Add to dashboard Cite

show abstract

“…The subsequent reconstitution of habitats may have triggered new faunal radiations that are considerably younger than lineages that have experienced long-term stability. East African examples of this second extreme are Lake Victoria that desiccated completely during the Late Pleistocene Stager & Johnson 2008), and the palaeolacustrine systems in the Turkana Basin (Brown & Feibel 1991;Van Bocxlaer et al 2008).…”

Section: Introductionmentioning

confidence: 99%

“…Such aquatic systems may permit the study of consecutive evolutionary phases in the process of adaptive radiation, thus providing additional insights into speciation processes and how they are affected by the abiotic setting. A candidate for this intermediate type is Lake Malawi ( Van Bocxlaer 2005;Seehausen 2006), the southernmost African Great Lake. At present, the lake (maximum depth 706 m; Spigel & Coulter 1996) largely fills the Malawi Rift, which started to develop approximately 8.6 Myr ago (Ebinger et al 1987(Ebinger et al , 1989Delvaux 1995;Ring & Betzler 1995).…”

Section: Introductionmentioning

confidence: 99%

Old fossils–young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi

et al. 2009

Self Cite

View full text Add to dashboard Cite

Studies on environmental changes provide important insights into modes of speciation, into the (adaptive) reoccupation of ecological niches and into species turnover. Against this background, we here examine the history of the gastropod genus Lanistes in the African Rift Lake Malawi, guided by four general evolutionary scenarios, and compare it with patterns reported from other endemic Malawian rift taxa. Based on an integrated approach using a mitochondrial DNA phylogeny and a trait-specific molecular clock in combination with insights from the fossil record and palaeoenvironmental data, we demonstrate that the accumulation of extant molecular diversity in the endemic group did not start before approximately 600 000 years ago from a single lineage. Fossils of the genus from the Malawi Rift, however, are over one million years older. We argue that severe drops in the lake level of Lake Malawi in the Pleistocene offer a potential explanation for this pattern. Our results also challenge previously established phylogenetic relationships within the genus by revealing parallel evolution and providing evidence that the endemic Lanistes species are not restricted to the lake proper but are present throughout the Malawi Rift.

show abstract

“…However, several statistical analyses of fossils have failed to reveal that natural selection had a strong influence on the evolution of phenotypic traits. For instance, the gradual change in shell morphology in the Pliocene-Holocene Turkana Basin malacofauna may reflect biological invasions, but no traces of a ''struggle for life'' are apparent in these fossils (Van Bocxlaer et al 2008). Hence, some paleobiologists are not convinced that directional selection was the causative agent which shaped the phenotype and life cycle in some welldocumented groups of fossil organisms (Hunt et al 2008).…”

Section: Directional Natural Selection In the Fossil Recordmentioning

confidence: 98%

Symbiogenesis, natural selection, and the dynamic Earth

Kutschera

2009

Theory Biosci.

View full text Add to dashboard Cite

One century ago, Constantin S. Mereschkowsky introduced the symbiogenesis theory for the origin of chloroplasts from ancient cyanobacteria which was later supplemented by Ivan E. Wallin's proposal that mitochondria evolved from once free-living bacteria. Today, this Mereschkowsky-Wallin principle of symbiogenesis, which is also known as the serial primary endosymbiosis theory, explains the evolutionary origin of eukaryotic cells and hence the emergence of all eukaryotes (protists, fungi, animals and plants). In 1858, the concept of natural selection was described independently by Charles Darwin and Alfred R. Wallace. In the same year, Antonio Snider-Pellegrini proposed the idea of shifting continents, which was later expanded by Alfred Wegener, who published his theory of continental drift eight decades ago. Today, directional selection is accepted as the major cause of adaptive evolution within natural populations of micro- and macro-organisms and the theory of the dynamic Earth (plate tectonics) is well supported. In this article, I combine the processes and principles of symbiogenesis, natural selection and the dynamic Earth and propose an integrative 'synade-model' of macroevolution which takes into account organisms from all five Kingdoms of life.

show abstract

Gradual Versus Punctuated Equilibrium Evolution in the Turkana Basin Molluscs: Evolutionary Events or Biological Invasions?

Abstract: A running controversy in evolutionary thought was Eldredge and Gould

Cited by 55 publications

References 41 publications

Flatfishes, Turtles, and Bolyerine Snakes: Evolution by Small Steps or Large, or Both?

Flatfishes, Turtles, and Bolyerine Snakes: Evolution by Small Steps or Large, or Both?

Old fossils–young species: evolutionary history of an endemic gastropod assemblage in Lake Malawi

Symbiogenesis, natural selection, and the dynamic Earth

Contact Info

Product

Resources

About