Ecological Speciation (Oxford Series in Ecology and Evolution)

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After nasal surgery.After nasal surgery the inside of the nose and can often be left raw and sore. The mucus produced by the nose can become dry and form a crust. This drying can mean that healing is delayed and infection can develop Turner, T. L., Hahn, M. W. & Nuzhdin, S. V. Genomic islands of speciation in Anopheles gambiae. PLoS Biology 3, e285 (2005). doi:10.1371/journal.pbio.0030285 Nasal CPAP and oxygen therapy - nasal CPAP and oxygen therapy may cause nasal dryness or congestion. Flo Nozoil has been clinically trialled in CPAP therapy and shown to help alleviate nasal dryness and improve the comfort of CPAP treatment. There is abundant evidence in plants that crosses between ploidy levels are less successful than crosses within ploidy levels, due in large part to a mismatch between the ploidy of the developing embryo and the ploidy of the endosperm ( Ramsey and Schemske 1998). The fertility of progeny produced from between-ploidy crosses is also much reduced due to a high frequency of chromosomal duplications and deficiencies that render gametes inviable ( Ramsey and Schemske 1998; Husband and Sabara 2004). Furthermore, these reproductive barriers are present immediately following hybrid formation; hence, it is reasonable to conclude that such postzygotic isolation might cause speciation without ecological divergence. To illustrate this point, consider two allopatric populations experiencing divergent selection. If divergent selection based on habitat differences is strong, habitat isolation will begin to evolve first as effective geographic isolation becomes ecogeographic isolation. Other forms of reproductive isolation, such as mating isolation or intrinsic postzygotic isolation will eventually evolve, and the potential strength of these components will increase with time. It is important to note that the relative contribution of these forms of isolation depends largely on the geographical arrangement of populations in the future. If populations remain allopatric, most barriers (with the exception of ecogeographic isolation) will not be realized in nature. If populations become sympatric in the future, some portion of the potential strength of other barriers could be realized, and their contribution to total reproductive isolation would increase.

To assess the strength of ecogeographic isolation, the projected niche maps for two taxa can be overlaid and the degree of allopatry in projected niche models estimated. This can be done separately for the two taxa under consideration, as there will often be asymmetries in how much isolation each experiences. If a projected niche model shows that suitable habitat for taxa X and O is found only in their current ranges ( Fig. 4B), we would conclude that the current geographic separation between them, i.e., the effective geographic isolation, is a direct consequence of genetically based, ecological differences, and therefore ecogeographic isolation is 1. Alternatively, if historical processes were solely responsible for the effective geographic separation, niche models would show that equally suitable habitat for both species is found throughout each other's geographic range ( Fig. 4C). In this case, there is no ecogeographic isolation. In the third scenario, niche modeling shows that half of the geographic range of taxon X is suitable for taxon O, and vice versa. Therefore, the zone of overlap in projected niche models represents the region in which both taxa could live if not limited by dispersal, and ecogeographic isolation is estimated as 0.5 ( Fig. 4D). Ritchie, M. G. Sexual selection and speciation. Annual Review of Ecology, Evolution, and Systematics 38, 79–102 (2007). Whether we view polyploid speciation as ecological or nonecological is largely a semantic argument. If we recognize a polyploid as a new species at the time of its origin, regardless of its ability to persist, then polyploid speciation is nonecological. If instead, polyploids are regarded as new species only if they can establish a self-sustaining population that is reproductively isolated from its progenitor, then polyploid speciation is often ecological. SPECIATION BY GENETIC DRIFT

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van Doorn, S., Edelaar, P. & Weissing, F. J. On the origin of species by natural and sexual selection. Science 326, 1704–1707 (2009).

We consider speciation to be ecological when externally imposed selection results in reproductive isolation; therefore, speciation by drift is nonecological. Although factors that influence the magnitude of genetic drift, such as variation in population size or mating success, may often have an ecological basis, this does not imply that speciation mediated by genetic drift is also “ecological.” The ecological speciation perspective has rekindled interest in the critical role of ecological factors in speciation, so in this sense it has been extremely valuable. However, natural selection and ecological factors have been at the center of discussions about speciation mechanisms for many decades. Consider the classic studies of Dobzhansky and colleagues on mechanisms of reproductive isolation in Drosophila. Dobzhansky (1951) concluded that gene flow between Drosophila pseudoobscura and D. persimilis was prevented by at least seven different isolating mechanisms, including such ecological factors as differences in habitat, preferred foods, and activity periods. Hiesey et al. (1971) conducted landmark studies on two closely related species of monkeyflowers, Mimulus cardinalis and M. lewisii, and through extensive reciprocal transplant experiments, crossing studies, and physiological observations demonstrated unmistakably that ecology and natural selection were the major factors contributing to speciation. In birds, the extraordinary radiation of Hawaiian honeycreepers from a single common ancestor, with species differentially adapted for feeding on nectar, fruits, seeds, or insects ( Amadon 1950), must surely represent an irrefutable example of divergent natural selection as a major cause of reproductive isolation.

Flo Nozoil can be used in pregnancy and while breastfeeding. Can Flo Nozoil be used with other nasal medications? Divergent pollinator-selected style lengths in Mimulus cardinalis and M. lewisii lead to differentiated pollen tube lengths, reducing the amount of expected hybridization in mixed pollinations. Butlin, R. K., Galindo, J. & Grahame, J. W. Sympatric, parapatric or allopatric: The most important way to classify speciation? Philosophical Transactions of the Royal Society B: Biological Sciences 363, 2997–3007 (2008). Mayr (1942, 1947) judged ecological factors as the major drivers of speciation. In his classic paper “Ecological factors in speciation,” Mayr (1947) concluded that geographic isolation leads to the formation of segregated populations that experience different ecological conditions, leading to evolutionary divergence. In Animal Species and Evolution, Mayr (1963, p. 556) devoted an entire chapter to the role of ecology in speciation, and began the second paragraph as follows: “An exhaustive treatment of the indicated subject matter would require an entire book, for there is hardly an ecological factor that does not affect speciation directly or indirectly, actually or potentially.” Many other evolutionary biologists have also supported the notion that ecological divergence of populations is typically required for speciation. Simpson (1953, p. 234n) concluded “… speciation, the basic process of radiation, is normally adaptive,” and Grant (1981) provided numerous examples in which ecological factors are the primary isolating barriers between species.