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speciation_and_plasticity [2013/02/14 13:01] – [Background and general question] mkoppspeciation_and_plasticity [2019/03/21 09:21] (current) – external edit 127.0.0.1
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   * Here, we propose to develop mathematical models that will shed light on a topic of much recent interest: Whether speciation -- and, in particular, speciation with gene-flow, can be facilitated by phenotypic plasticity.   * Here, we propose to develop mathematical models that will shed light on a topic of much recent interest: Whether speciation -- and, in particular, speciation with gene-flow, can be facilitated by phenotypic plasticity.
  
-  * A species is most commonly defined as a group inter-fertile individuals that cannot reproduce with members of other species (Mayr 1942). Thus, understanding speciation requires understanding the evolution of reproductive isolation. +  * A **species** is most commonly defined as a group inter-fertile individuals that cannot reproduce with members of other species (Mayr 1942). Thus, understanding speciation requires understanding the evolution of reproductive isolation. 
   * According to the traditional view, speciation almost always requires a geographic barrier separating the range of an ancestral species (allopatric speciation). Two independently evolving subpopulations will then diverge between the nascent species (allopatric speciation) and become more and more incompatible, until they are recognized as separate species.   * According to the traditional view, speciation almost always requires a geographic barrier separating the range of an ancestral species (allopatric speciation). Two independently evolving subpopulations will then diverge between the nascent species (allopatric speciation) and become more and more incompatible, until they are recognized as separate species.
   * However, there is mounting evidence for the opposing view that speciation is also without a strict geographic barrier (parapatric or sympatric speciation). Such "speciation with gene-flow" (Smadja and Butlin 2011?) is theoretically challenging, because migration and hybridisation will counter-act genetic divergence, and because genetic recombination tends to destroy associations between sets of genes or characters. Most models of speciation with gene-flow assume a prominent role for divergent ecological selection pressures (Nosil 2012).     * However, there is mounting evidence for the opposing view that speciation is also without a strict geographic barrier (parapatric or sympatric speciation). Such "speciation with gene-flow" (Smadja and Butlin 2011?) is theoretically challenging, because migration and hybridisation will counter-act genetic divergence, and because genetic recombination tends to destroy associations between sets of genes or characters. Most models of speciation with gene-flow assume a prominent role for divergent ecological selection pressures (Nosil 2012).  
  
- +  * **Phenotypic plasticity** is the ability of organisms with identical genotype to produce different phenotypes in response to different environments (e.g. West-Eberhard 2003). It is pervasive in nature, and often is crucial in helping organisms cope with variable environments. 
-  * Phenotypic plasticity is the ability of organisms with identical genotype to produce different phenotypes in different environments. It is a general feature of all living beings, and in many cases is adaptive, because it helps organisms to cope with variable environments. +
   * Recently, plasticity has been advertised by some as a centerpiece of an "extended evolutionary synthesis" (West-Eberhard 2003, Piggliucci and Müller 2009?), which aims to unify traditional population genetics with evolutionary developmental biology.    * Recently, plasticity has been advertised by some as a centerpiece of an "extended evolutionary synthesis" (West-Eberhard 2003, Piggliucci and Müller 2009?), which aims to unify traditional population genetics with evolutionary developmental biology. 
-  * General thrust: Plasticity plays a leading role in (guiding) phenotypic evolution, including "evolutionary novelties" and diversification ("genes follow development") +  * The main argument is that plasticity plays a leading role evolution ("genes follow development"), including diversification and evolutionary novelties (West-Eberhard 2003). 
-  * In the context speciation, plasticity is thought to facilitate phenotypic/ecological divergence as well as evolution of RI. Suggested mechanisms include ... In particular, several of the proposed empirical examples (arctic charr etc.) imply speciation with gene flow. +  * In the context speciation, plasticity is thought to facilitate phenotypic/ecological divergence as well as the evolution of reproductive isolation (West-Eberhard 2003, Pfennig et al. 2010, Pfenning and McGhee 2010, Fitzpatrick 2012). [Suggested mechanisms include ...] In particular, several of the proposed examples imply speciation with gene flow (e.g., ...). 
   * However, many proposed scenarios rely on verbal models, and many details remain unclear. This is particularly true for scenarios involving plasticity in an ecological adaptation trait (but see Thibert-Plante and Hendry 2011).    * However, many proposed scenarios rely on verbal models, and many details remain unclear. This is particularly true for scenarios involving plasticity in an ecological adaptation trait (but see Thibert-Plante and Hendry 2011). 
   * Open questions include:   * Open questions include: