Compared to those of their parents, are the traits of first-generation (F1) hybrids typically
intermediate, biased toward one parent, or mismatched for alternative parental phenotypes …

Partial prezygotic isolation is often viewed as more important than partial postzygotic
isolation (low fitness of hybrids) early in the process of speciation. I simulate secondary …

This study aims to identify selection pressures during the historical process of homoploid
hybrid speciation in three Helianthus (sunflower) hybrid species. If selection against intrinsic …

Early-generation hybrid fitness is difficult to interpret because heterosis can obscure the
effects of hybrid breakdown. We used controlled reciprocal crosses and common garden …

The process of natural hybridization may produce genotypes that establish new evolutionary
lineages. However, many authors have concluded that natural hybridization is of little …

Homoploid speciation generates species without a change in chromosome number via
introgressive hybridization and has been considered rare in animals. Heliconius butterflies …

Conditions for polymorphism at pleiotropic loci with antagonistic effects on fitness
components are investigated, under the assumptions of additivity and multiplicativity of …

Results from several physiologically based manipulations were synthesized to investigate
two selective trade-offs involving offspring number versus offspring quality and costs of …

How strong is phenotypic selection on quantitative traits in the wild? We reviewed the
literature from 1984 through 1997 for studies that estimated the strength of linear and …

Abstract In 1983, Russell Lande and Stevan Arnold published “The measurement of
selection on correlated characters,” which became a highly influential citation classic in …