Related Experiment Videos
Weighting and congruence: a case study based on three mitochondrial genes in pitvipers
1Service de Systématique moléculaire (CNRS GDR 1005), Laboratoire d'Ichtyologie générale et appliquée, Muséum National d'Histoire Naturelle, 43 rue Cuvier, Paris Cedex 05, 75231, France.
Molecular Phylogenetics and Evolution
|July 21, 1998
Summary
This study suggests removing incongruent substitutions, not homoplasy, to improve phylogenetic analysis congruence in pitvipers. Analyzing mitochondrial genes revealed distinct incongruence patterns across codon positions.
Area of Science:
- Evolutionary biology
- Phylogenetics
- Molecular evolution
Background:
- Phylogenetic analyses often employ weighting strategies to minimize homoplasy and enhance data partition congruence.
- Incongruence, particularly within and between mitochondrial genes of pitvipers (Crotalinae), poses challenges for accurate evolutionary reconstruction.
- Codon positions within genes exhibit varying degrees of incongruence, with third positions showing distinct patterns across genes.
Purpose of the Study:
- To investigate incongruence patterns within and between mitochondrial genes in pitvipers.
- To evaluate the effectiveness of removing incongruent substitutions versus homoplasy in phylogenetic analysis.
- To clarify the phylogenetic positions of key pitviper genera and biogeographic groupings.
Main Methods:
- Utilized the Farris et al. incongruence test on three mitochondrial genes from pitvipers.
- Partitioned data by codon position for coding genes to assess positional incongruence.
- Applied a novel approach advocating for the removal of incongruent substitutions.
Main Results:
- Incongruence between codon positions within a gene can be more significant than incongruence between analogous positions in different genes.
- Third codon positions display divergent incongruence patterns across genes, despite similar saturation trends.
- The genera Calloselasma and Hypnale represent the most basal lineages within Crotalinae.
- Asiatic pitvipers were found to be paraphyletic, whereas American pitvipers formed a monophyletic group.
Conclusions:
- Removing incongruent substitutions is a more effective strategy for improving phylogenetic congruence than removing homoplasy.
- Mitochondrial gene data reveal complex incongruence patterns that necessitate careful analytical approaches.
- The phylogenetic framework supports the basal divergence of Calloselasma and Hypnale and clarifies the paraphyletic nature of Asiatic pitvipers versus the monophyletic American pitvipers.