What do we need to know about speciation? (original) (raw)
Related papers
Ecological speciation: Ecological speciation
Ecology Letters, 2005
Ecological processes are central to the formation of new species when barriers to gene flow (reproductive isolation) evolve between populations as a result of ecologically-based divergent selection. Although laboratory and field studies provide evidence that Ôecological speciationÕ can occur, our understanding of the details of the process is incomplete. Here we review ecological speciation by considering its constituent components: an ecological source of divergent selection, a form of reproductive isolation, and a genetic mechanism linking the two. Sources of divergent selection include differences in environment or niche, certain forms of sexual selection, and the ecological interaction of populations. We explore the evidence for the contribution of each to ecological speciation. Forms of reproductive isolation are diverse and we discuss the likelihood that each may be involved in ecological speciation. Divergent selection on genes affecting ecological traits can be transmitted directly (via pleiotropy) or indirectly (via linkage disequilibrium) to genes causing reproductive isolation and we explore the consequences of both. Along with these components, we also discuss the geography and the genetic basis of ecological speciation. Throughout, we provide examples from nature, critically evaluate their quality, and highlight areas where more work is required.
Ecology Letters, 2005
Ecological processes are central to the formation of new species when barriers to gene flow (reproductive isolation) evolve between populations as a result of ecologically-based divergent selection. Although laboratory and field studies provide evidence that Ôecological speciationÕ can occur, our understanding of the details of the process is incomplete. Here we review ecological speciation by considering its constituent components: an ecological source of divergent selection, a form of reproductive isolation, and a genetic mechanism linking the two. Sources of divergent selection include differences in environment or niche, certain forms of sexual selection, and the ecological interaction of populations. We explore the evidence for the contribution of each to ecological speciation. Forms of reproductive isolation are diverse and we discuss the likelihood that each may be involved in ecological speciation. Divergent selection on genes affecting ecological traits can be transmitted directly (via pleiotropy) or indirectly (via linkage disequilibrium) to genes causing reproductive isolation and we explore the consequences of both. Along with these components, we also discuss the geography and the genetic basis of ecological speciation. Throughout, we provide examples from nature, critically evaluate their quality, and highlight areas where more work is required.
A framework for comparing processes of speciation in the presence of gene flow
Molecular Ecology, 2011
How common is speciation-with-gene-flow? How much does gene flow impact on speciation? To answer questions like these requires understanding of the common obstacles to evolving reproductive isolation in the face of gene flow and the factors that favour this crucial step. We provide a common framework for the ways in which gene flow opposes speciation and the potential conditions that may ease divergence. This framework is centred on the challenge shared by most scenarios of speciation-withgene-flow, i.e. the need for coupling among different components of reproductive isolation. Using this structure, we review and compare the factors favouring speciation with the intention of providing a more integrated picture of speciation-with-gene-flow.
Ecological divergence promotes the evolution of cryptic reproductive isolation
Proceedings of the Royal Society B: Biological Sciences, 2006
Speciation can involve the evolution of 'cryptic' reproductive isolation that occurs after copulation but before hybrid offspring are produced. Because such cryptic barriers to gene exchange involve post-mating sexual interactions, analyses of their evolution have focused on sexual conflict or traditional sexual selection. Here, we show that ecological divergence between populations of herbivorous walking sticks is integral to the evolution of cryptic reproductive isolation. Low female fitness following between-population mating can reduce gene exchange between populations, thus acting as a form of cryptic isolation. Female walking sticks show reduced oviposition rate and lower lifetime fecundity following between-population versus within-population mating, but only for mating between populations using different host-plant species. Our results indicate that even inherently sexual forms of reproductive isolation can evolve as a byproduct of ecological divergence and that post-mating sexual interactions do not necessarily evolve independently of the ecological environment.
Ecological Divergence and the Origins of Intrinsic Postmating Isolation with Gene Flow
International Journal of Ecology, 2011
The evolution of intrinsic postmating isolation has received much attention, both historically and in recent studies of speciation genes. Intrinsic isolation often stems from between-locus genetic incompatibilities, where alleles that function well within species are incompatible with one another when brought together in the genome of a hybrid. It can be difficult for such incompatibilities to originate when populations diverge with gene flow, because deleterious genotypic combinations will be created and then purged by selection. However, it has been argued that if genes underlying incompatibilities are themselves subject to divergent selection, then they might overcome gene flow to diverge between populations, resulting in the origin of incompatibilities. Nonetheless, there has been little explicit mathematical exploration of such scenarios for the origin of intrinsic incompatibilities during ecological speciation with gene flow. Here we explore theoretical models for the origin of intrinsic isolation where genes subject to divergent natural selection also affect intrinsic isolation, either directly or via linkage disequilibrium with other loci. Such genes indeed overcome gene flow, diverge between populations, and thus result in the evolution of intrinsic isolation. We also examine barriers to neutral gene flow. Surprisingly, we find that intrinsic isolation sometimes weakens this barrier, by impeding differentiation via ecologically based divergent selection.
On The Topic of Species and Speciation in Biology
After a long period of static species concept, followed modern times with new technologies of investigations and wider vision of most systematists who accepted the dynamic species outlook. Adopting population thinking, it was also accepted importance of intra-and interpopulation variation due to geographical and other forms of isolation. The key words-reproductive isolation are referring to the way of a community or part of a population are becoming genetically very different from other populations; it is so called genetic incompatibility of interbreeding. Thus, appeared the meaning of biological species concept (BSC). Because deep differences arise in a long time and in a certain area, the scientists are underlining the historical, geographical, natural and objective character of the biological species. In details there are many types of speciation, but finally the species is considered as the main unit of evolution. In case of allopatric speciation, the size of population, the spread and colonization of new areas as well as potential effect of genetic drift are very important. Underground habitats, the unique ecological conditions of ocean depth, orogenetic movements (e.g. mountain rising) and glaciations, were additional factors that determined speciation and endemism phenomenon. Mutual relations or co-speciation also play an important role in opening new evolutionary lines.