Related Experiment Video
Updated: Jul 31, 2026
07:49
Creating and Applying a Reference to Facilitate the Discussion and Classification of Proteins in a Diverse Group
Published on: August 16, 2017
Character analysis in morphological phylogenetics: problems and solutions
1Section of Amphibians and Reptiles, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania 15213-4080, USA. wiensj@carnegiemuseums.org
Systematic Biology
|July 16, 2002
Summary
This study proposes coding morphological characters as continuous quantitative traits to address issues in phylogenetic analysis. This new method, applied to hoplocercid lizards, reveals significant phylogenetic structure in quantitative data.
Area of Science:
- Systematics
- Evolutionary Biology
- Phylogenetics
Background:
- Morphological phylogenetics faces theoretical controversies and practical inconsistencies in empirical studies.
- Most morphological variation is fundamentally quantitative, irrespective of qualitative or quantitative coding by systematists.
Purpose of the Study:
- To propose a unified solution for defining, delimiting, and ordering morphological character states.
- To introduce a novel parsimony method for analyzing quantitative traits as continuous variables in phylogenetic reconstruction.
Main Methods:
- Coding morphological characters as continuous quantitative traits.
- Implementing a new parsimony method: step-matrix gap-weighting, a modification of Thiele's approach.
- Reviewing and describing three solutions for scaling or weighting quantitative characters.
Main Results:
- Application of the new coding method to hoplocercid lizard data.
- Demonstrated sensitivity of phylogenetic conclusions to different scaling methods.
- Quantitative data, when coded using the new approach, exhibit significant phylogenetic structure and comparable homoplasy to qualitative data.
Conclusions:
- Coding morphological characters as continuous quantitative traits offers a potential solution to fundamental problems in character analysis.
- The proposed method successfully analyzes quantitative data, revealing phylogenetic structure and homoplasy.
- Despite some objections, continuous quantitative characters can contain significant phylogenetic information.
Related Concept Videos
01:23Phylogeny
Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire...
03:21Phylogenetic Trees
Phylogenetic trees come in many forms. It matters in which sequence the organisms are arranged from the bottom to the top of the tree, but the branches can rotate at their nodes without altering the information. The lines connecting individual nodes can be straight, angled, or even curved.The length of the branches can depict time or the relative amount of change among organisms. For instance, the branch length might indicate the number of amino acid changes in the sequence that underlies the...
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
02:54Evolutionary Relationships through Genome Comparisons
Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is that if two species share a common feature, it is likely encoded by the DNA sequence conserved between both species. The advent of genome sequencing technologies in the late 20th century enabled scientists to understand the concept of conservation of domains between species and helped them to deduce evolutionary relationships across diverse...
03:21Phylogenetic Trees
Phylogenetic trees come in many forms. It matters in which sequence the organisms are arranged from the bottom to the top of the tree, but the branches can rotate at their nodes without altering the information. The lines connecting individual nodes can be straight, angled, or even curved.The length of the branches can depict time or the relative amount of change among organisms. For instance, the branch length might indicate the number of amino acid changes in the sequence that underlies the...
01:28Microbial Phylogeny
Understanding the evolutionary relationships among microorganisms is fundamental to microbial ecology and taxonomy. Phylogenetic trees are essential tools for inferring these relationships, relying primarily on comparative analyses of molecular sequences such as DNA, RNA, or proteins. In microbial studies, these trees typically depict the evolutionary paths of diverse bacterial and archaeal species by mapping genetic differences accumulated over time.Phylogenetic trees are composed of tips,...