title: The effect of positive selection on a sexual reproduction gene in Thalassiosira weissflogii (Bacillariophyta): results obtained from maximum-likelihood and parsimony-based methods.
abstract: Maximum-Likelihood-based and parsimony-based methods were used to test for potential effects of positive selection on the sexually induced gene 1 (Sig1) in Thalassiosira weissflogii. The Sig proteins are thought to play a role in mediating sperm-egg recognition during the sexual reproduction phase. The results obtained from parsimony-based analyses showed that none of the amino acid sites were influenced by positive selection. Maximum-likelihood analyses indicated that positive selection was affecting a maximum of seven and a minimum of four amino acid sites in the polypeptide derived from Sig1. It was concluded that the results obtained from the maximum-likelihood-based method are more reliable than those obtained from the parsimony-based approach. This is apparently the first study that has shown that reproductive proteins in unicellular eukaryotes are influenced by positive selection.
authors.affiliation: Department of Biology and Health Services, Edinboro University of Pennsylvania, USA. usorhannus@edinboro.edu
authors.forename: Ulf
authors.initials: U
authors.lastname: Sorhannus
mesh_terms: D000465:Algorithms; D000818:Animals; D003062:Codon / Q000235:genetics*; D017377:Diatoms / Q000235:genetics* / Q000502:physiology; D019143:Evolution, Molecular; D014644:Genetic Variation; D016013:Likelihood Functions; D010802:Phylogeny; D011506:Proteins / Q000032:analysis / Q000235:genetics*; D015800:Protozoan Proteins; D012098:Reproduction / Q000235:genetics; D012641:Selection, Genetic
chemical_list: D003062:Codon; D011506:Proteins; D015800:Protozoan Proteins; C121131:Sexually induced protein 1, Thalassiosira weissflogii