Introduction ....................................................................................................................................283 DeÞning a Species and Symbiont..................................................................................................284 Wolbachia as a Model System for Symbiont-Induced Speciation................................................285 Abund...

When John Maynard Smith (1966) wrote on sympatric speciation more than 35 years ago, he acknowledged that the argument “whether speciation can occur in a sexually reproducing species without effective geographical isolation” was an old problem and voiced his opinion that the “present distribution of species is equally consistent either with the sympatric or the allopatric theory.” Yet, from the...

This research describes the development of a dual preservationand field-speciation technique for As(III) and As(V) speciation of a sample preserved with ethylenediaminetetraacetic acid (EDTA) and acetic acid (HAc). The new method was compared with existing preservationand field-speciation methods and was shown to be accurate and precise in spite of possible interference from ferrous iron in the...

Studies of hybrid inviability, sterility and 'speciation genes' in Drosophila have given insight into the genetic changes that result in reproductive isolation. Here, I survey some extraordinary and important advances in Drosophila speciation research. However, 'reproductive isolation' is not the same as 'speciation', and this Drosophila work has resulted in a lopsided view of speciation. In pa...

The hypothesis of punctuated equilibrium proposes that most phenotypic evolution occurs in rapid bursts associated with speciation events. Several methods have been developed that can infer punctuated equilibrium from molecular phylogenies in the absence of paleontological data. These methods essentially test whether the variance in phenotypes among extant species is better explained by evoluti...

Sympatric speciation requires coexistence of the newly formed species. If divergence proceeds by small mutational steps, the new species utilize almost the same resources initially, and full speciation may be impeded by competitive exclusion in stochastic environments. We investigate this primarily ecological problem of sympatric speciation by studying the population dynamics of a diverging ase...

The extraordinary species richness of teleost fishes has attracted much research on mechanisms and modes of speciation. We here review research on speciation in freshwater fish in light of speciation theory, and place this in a context of knowledge about broad-scale diversity patterns in freshwater fishes. We structure our review around the major axes of divergence during speciation in freshwat...

To understand speciation, we first need to know what species are. Yet debates over species concepts have seemed endless, with little obvious relevance to the study of speciation. Recently, there has been progress in resolving these debates, favoring a lineage-based, evolutionary species concept. This progress calls for reconsideration of the study of speciation. Traditional speciation research ...

A remarkable suite of forms of genomic conflict has recently been implicated in speciation. We propose that these diverse roles of genomic conflict in speciation processes can be unified using the concept of 'conflictual speciation'. Conflictual speciation centers on the evolution of reproductive isolation as a byproduct of antagonistic selection among genomic elements with divergent fitness in...

The tradition of classifying cases of speciation into discrete geographic categories (allopatric, parapatric and sympatric) fuelled decades of fruitful research and debate. Not surprisingly, as the science has become more sophisticated, this simplistic taxonomy has become increasingly obsolete. Geographic patterns are now reasonably well understood. Sister species are rarely sympatric, implying...