The role of pleiotropy and population structure in the evolution of altruism through the greenbeard effect.

Several empirical examples and theoretical models suggest that the greenbeard effect may be an important mechanism in driving the evolution of altruism. However, previous theoretical models rely on assumptions such as spatial structure and specific sets of pleiotropic loci, the importance of which for the evolution of altruism has not been studied. Here, we develop a population-genetic model that clarifies the roles of extrinsic assortment (e.

Senescence evolution under the catastrophic accumulation of deleterious mutations.

For aging to evolve, selection against mortality must decrease with age. This prevailing view in the evolutionary theory of senescence posits that mutations with deleterious effects happening late in life-when purging selection is weak-may become fixed via genetic drift in the germline, and produce a senescent phenotype. Theory, however, has focused primarily on growing populations and the fate of single deleterious mutations.

Negative Coupling: The Coincidence of Premating Isolating Barriers Can Reduce Reproductive Isolation.

Speciation can be mediated by a variety of reproductive barriers, and the interaction among different barriers has often been shown to enhance overall reproductive isolation, a process referred to as "coupling." Here, we analyze a population genetics model to study the establishment of linkage disequilibrium (LD) among loci involved in multiple premating barriers, an aspect that has received little theoretical attention to date. We consider a simple genetic framework underlying two distinct premating barriers, each encoded by a preference locus and its associated mating trait locus.

The interplay of local adaptation and gene flow may lead to the formation of supergenes.

Supergenes are genetic architectures resulting in the segregation of alternative combinations of alleles underlying complex phenotypes. The co-segregation of alleles at linked loci is often facilitated by polymorphic chromosomal rearrangements suppressing recombination locally. Supergenes are involved in many complex polymorphisms, including sexual, colour or behavioural polymorphisms in numerous plants, fungi, mammals, fish, and insects.

Structural Variants and Speciation: Multiple Processes at Play.

Research on the genomic architecture of speciation has increasingly revealed the importance of structural variants (SVs) that affect the presence, abundance, position, and/or direction of a nucleotide sequence. SVs include large chromosomal rearrangements such as fusion/fissions and inversions and translocations, as well as smaller variants such as duplications, insertions, and deletions (CNVs). Although we have ample evidence that SVs play a key role in speciation, the underlying mechanisms differ depending on the type and length of the SV, as well as the ecological, demographic, and historical context.