Directional selection is the primary cause of phenotypic diversification.

@article{citeulike:500247, abstract = {Selection is widely accepted as the principal force shaping phenotypic variation within populations. Its importance in speciation and macroevolution has been questioned, however, because phenotypic differences between species or higher taxa sometimes appear to be nonadaptive. Here, we use the quantitative trait locus (QTL) sign test to evaluate the importance of directional selection in phenotypic divergence. If a trait has a history of directional selection, QTL effects should be mostly in the same direction; otherwise QTLs with antagonistic effects should be common. Analysis of QTL effects for 572 traits from 86 studies revealed significantly fewer antagonistic QTLs than expected under neutrality, a result that validates Darwin's claim that phenotypic diversification is caused mainly by selection. Moreover, interspecific trait differences were more strongly or consistently selected than intraspecific differences, strengthening a growing consensus among students of speciation that directional selection is the primary cause of speciation. Contrary to studies of selection in contemporary populations, life history traits appear to be selected more strongly than morphological traits, but traits related to the timing of development are weakly selected relative to most other traits.}, address = {Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA. lriesebe@indiana.edu}, author = {Rieseberg, L. H. and Widmer, A. and Arntz, A. M. and Burke, J. M. }, citeulike-article-id = {500247}, doi = {10.1073/pnas.192360899}, issn = {0027-8424}, journal = {Proc Natl Acad Sci U S A}, keywords = {directional-selection, diversification}, month = {September}, number = {19}, pages = {12242--12245}, posted-at = {2007-11-15 05:56:15}, priority = {2}, title = {Directional selection is the primary cause of phenotypic diversification.}, url = {http://dx.doi.org/10.1073/pnas.192360899}, volume = {99}, year = {2002} }

TY - JOUR ID - citeulike:500247 L3 - citeulike-article-id:500247 TI - Directional selection is the primary cause of phenotypic diversification. JF - Proc Natl Acad Sci U S A VL - 99 IS - 19 SP - 12242 EP - 12245 AD - Department of Biology, Indiana University, Bloomington, IN 47405-3700, USA. lriesebe@indiana.edu SN - 0027-8424 N2 - Selection is widely accepted as the principal force shaping phenotypic variation within populations. Its importance in speciation and macroevolution has been questioned, however, because phenotypic differences between species or higher taxa sometimes appear to be nonadaptive. Here, we use the quantitative trait locus (QTL) sign test to evaluate the importance of directional selection in phenotypic divergence. If a trait has a history of directional selection, QTL effects should be mostly in the same direction; otherwise QTLs with antagonistic effects should be common. Analysis of QTL effects for 572 traits from 86 studies revealed significantly fewer antagonistic QTLs than expected under neutrality, a result that validates Darwin's claim that phenotypic diversification is caused mainly by selection. Moreover, interspecific trait differences were more strongly or consistently selected than intraspecific differences, strengthening a growing consensus among students of speciation that directional selection is the primary cause of speciation. Contrary to studies of selection in contemporary populations, life history traits appear to be selected more strongly than morphological traits, but traits related to the timing of development are weakly selected relative to most other traits. KW - directional-selection KW - diversification AU - Rieseberg, LH AU - Widmer, A AU - Arntz, AM AU - Burke, JM PY - 2002/09/17/ UR - http://dx.doi.org/10.1073/pnas.192360899 ER -