Divergent natural selection has been shown to promote speciation in many taxa. However, although divergent selection often initiates the process of speciation, it often fails to complete it. Several time-based, geographic and genetic factors have been recognized to explain this variability in how far speciation proceeds. We review here recent evidence indicating that variability in the complete...

Where divergent ecological adaptation also leads to assortative mating between populations, speciation is facilitated. We have extensively studied two examples from among the Lepidoptera, in which ecologically selected traits have pleiotropic effects on the mating system. Based on our understanding of mating behaviour and pleiotropy derived from these empirical examples, we here review pleiotro...

Emerging diseases represent a growing worldwide problem accompanying global environmental changes. There is tremendous interest in identifying the factors controlling the appearance and spread of these diseases. Here, we discuss emerging fungal plant diseases, and argue that they often result from host shift speciation (a particular case of ecological speciation). We consider the factors contro...

The role of natural selection in promoting reproductive isolation has received substantial renewed interest within the last two decades. As a consequence, the study of ecological speciation has become an extremely productive research area in modern evolutionary biology. Recent innovations in sequencing technologies offer an unprecedented opportunity to study the mechanisms involved in ecologica...

Evolutionary biologists have often suggested that ecology is important in speciation, in that natural selection may drive adaptive divergence between lineages that inhabit different environments. I suggest that it is the tendency of lineages to maintain their ancestral ecological niche (phylogenetic niche conservatism) and their failure to adapt to new environments which frequently isolates inc...

The tropics contain far greater numbers of species than temperate regions, suggesting that rates of species formation might differ systematically between tropical and non-tropical areas. We tested this hypothesis by reconstructing the history of speciation in New World (NW) land birds using BAMM, a Bayesian framework for modelling complex evolutionary dynamics on phylogenetic trees. We estimate...

The health effects of aerosol depend on the size distribution and the chemical composition of the particles. Heavy metals of anthropogenic origin are connected to the fine aerosol fraction (PM2.5). The composition and speciation of aerosols can be variable in time, due to the time-dependence of anthropogenic sources as well as meteorological conditions. Synchrotron-radiation total-reflection X-...

Climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions. However, the impact climatic drying and subsequent tropical rainforest contraction had on speciation has been controversial because of inconsistent palaeoecological and genetic data. Despite the strong interest in examining the role of climatic change on speciation in the Neotropic...

Explosive speciation in ancient lakes has fascinated biologists for centuries and has inspired classical work on the tempo and modes of speciation. Considerable attention has been directed towards the extrinsic forces of speciation--the geological, geographical and ecological peculiarities of ancient lakes. Recently, there has been a resurgence of interest in the intrinsic nature of these radia...

Speciation as a process remains a central focus of evolutionary biology, but our understanding of the genomic architecture and prevalence of speciation in the face of gene flow remains incomplete. The Anopheles gambiae species complex of malaria mosquitoes is a radiation of ecologically diverse taxa. This complex is well-suited for testing for evidence of a speciation continuum and genomic barr...