Macroevolution
Under Macro Evolution is understood evolutionary bulk transitions that occur across species and also lead to the emergence of new taxa such as genera, families, orders, classes or tribes. These documented descent processes have taken place at the level of complex -built organisms or aquatic protozoa.
Terminology
Evolutionary biologists generally go on the assumption that most of the operations of macroevolution run on the same principles as those of micro-evolution, which describes evolutionary processes within or at the level of species. It is therefore in the macroevolution complex creatures built a continuation mikroevolutiver processes over long periods of time ( millions of years ). While some evolutionary biologists, the term " macroevolution " to use when referring to the evolutionary emergence of new " body plans " (eg by fossil sequences occupied transition from predatory dinosaurs to birds in the Mesozoic ), most people reject the differentiation of macro-and microevolution, since it suggests a non- real-world difference. Some biologists - including Richard Goldschmidt - have tried to explain key events of macroevolution with larger mutation jumps, for which there is currently no convincing evidence. Experiments on homeotic genes have revived these ideas but partly (see section: research findings and hypotheses). At the level of aquatic unicellular new cell plans can cell fusion processes ( symbiogenesis ) in one step (eg, a source of marine phytoplankton ).
Research results and hypotheses
The study of the phylogeny of organisms is an interdisciplinary agenda at the next biologists and scientists from other disciplines collaborate (eg, paleontologists, see evolutionary biology ). Thus, for example, provide geology, stratigraphy and geochemistry datings for the first occurrence of new fossil -documented species, genera, and orders (eg reptiles to mammals ). The mechanisms of this gradual plan transformations are still the subject of research. Important significance for the macro-evolution of multicellular organisms, insofar as it is associated with greater changes in the basic morphology of the respective populations, have the Hox genes. So could in experiments with the fruit fly Drosophila melanogaster and the brine shrimp, by relatively simple mutations within the Hox genes, the body structure can be changed so much that this development sechsfüßiger insects from cancerous ancestors is explainable.
Another concept of macro- evolution research is to, inter alia, by Andrew H. Knoll represented " permissive Ecology " (Eng. " tolerant Ecology "). In certain situations, such as for global environmental disasters, large potential habitats for a Massenextinktion for re-colonizing other populations are free. Unlike in an environment where their ecological niches are already occupied by well-adapted species, in such situations, even -matched individuals with different characteristics of the population have a high survival and reproductive opportunity. In this configuration, an accelerated evolution with large phenotypic changes and significant variations in morphology is possible; these processes are referred to as adaptive radiations. AR Knoll suggests this before as an explanation for the Cambrian explosion species, since after the end of a global glaciation wide areas must be vacated.
Early impetus for this hypothesis have been since the beginning of the 1960s and Others Ernst Mayr and Stephen Jay Gould, and in the 1980s, Elisabeth Vrba.
Alternative concepts
Representatives of the controversial, religion-based positions creationism and intelligent design advocate the distinction between macro and micro evolution. While they accept microevolution here as an empirically confirmed by evolutionary biology mechanism, they reject massive blueprint transformations within the meaning of macroevolution from as an explanation for the evolution of species. Creationists represent a basic type concept based on divine or personal creation and subsequent depletion of the gene pool and selection.
They find that sufficient evidence supporting the plan transformations that have led to the emergence of new genres would still stand. Previous findings of research on macro-evolution - as the fossil documented plan transformations, as evidenced by cell and molecular biological analysis cell fusion processes and the observed transformations of the body structure of insects due to mutated Hox genes - they do not accept as sufficient evidence. Critics such as the human biologist Eugenie C. Scott and Glenn Branch contact the philosopher therefore, that this objection the structure of an argumentum ad ignorantiam ( Latin for " argument that appeals to the ignorance" ) plays (cf. Intelligent design). They refer in turn to the lack of empirical falsifiability principle of creationism and intelligent design. The plant physiologist and evolutionary biologist Ulrich Kutschera accuses creationists and representatives of Intelligent Design to operate pseudoscience.