Reticulate or tree-like chloroplast DNA evolution in Sileneae (Caryophyllaceae)?
1Department of Systematic Botany, Evolutionary Biology Centre, Uppsala University, Norbyv 18D, SE-75236 Uppsala, Sweden. per.erixon@ebc.uu.se
Molecular Phylogenetics and Evolution
|May 21, 2008
Summary
Phylogenetic analysis of Sileneae using chloroplast DNA revealed high homoplasy and rapid radiation, hindering resolution. However, new insights suggest potential homoploid hybrid origins and paraphyly within the Silene genus.
Area of Science:
- Plant evolutionary biology
- Molecular phylogenetics
- Systematics of the Caryophyllaceae family
Background:
- Phylogenetic relationships within the Sileneae tribe remain poorly resolved despite extensive chloroplast DNA (cpDNA) sequencing.
- Previous studies have faced challenges due to rapid radiation and substitution rate heterogeneity, leading to low support for key phylogenetic nodes.
Purpose of the Study:
- To investigate the phylogenetic relationships within the Sileneae tribe using a large cpDNA dataset.
- To identify the causes of poor phylogenetic resolution and evaluate alternative evolutionary models, such as chloroplast recombination.
- To re-evaluate the monophyly of the genus Silene based on new molecular evidence.
Main Methods:
- Sequencing of up to 25kb of chloroplast DNA from 24 species within the Sileneae tribe.
- Phylogenetic analyses to infer evolutionary relationships.
- Evaluation of phylogenetic incongruence and assessment of alternative evolutionary models like homoplasy and ancient interspecific recombination.
Main Results:
- High levels of homoplasy were observed in the cpDNA data, contributing to poor resolution among closely related species.
- Several major phylogenetic relationships were confidently resolved, including the grouping of *S. cryptoneura* and *S. sordida*, suggesting a possible homoploid hybrid origin.
- The genera *S. atocioides* and *S. aegyptiaca* were resolved as a sister group to *Lychnis* and the remainder of *Silene*, indicating potential paraphyly of the genus *Silene*.
Conclusions:
- Rapid radiation and substitution rate heterogeneity, coupled with high homoplasy, present significant challenges for robust phylogenetic inference in Sileneae using cpDNA.
- The study provides strong evidence for previously unrecognized phylogenetic relationships, including potential homoploid hybrid origins and suggests that *Silene* may be paraphyletic.
- Further research incorporating nuclear DNA data and advanced phylogenetic methods is warranted to fully resolve the evolutionary history of Sileneae.
Related Concept Videos
01:08The Anatomy of Chloroplasts
Green algae and plants, including green stems and unripe fruit, harbor specialized organelles called chloroplasts to carry out photosynthesis. They coordinate both stages of photosynthesis — the light-dependent reactions and the light-independent reactions. The light-dependent reactions use sunlight to release oxygen and produce chemical energy in the form of ATP and NADPH, and the light-independent reactions capture CO2 and use ATP and NADPH to produce sugar.
Structure of Chloroplasts
A...
Structure of Chloroplasts
A...
02:26Non-vascular Seedless Plants
The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.
02:16Comparing Mitochondrial, Chloroplast, and Prokaryotic Genomes
The present-day mitochondrial and chloroplast genomes have retained some of the characteristics of their ancestral prokaryotes and also have acquired new attributes during their evolution within eukaryotic cells. Like prokaryotic genomes, mitochondrial and chloroplast genomes neither bind with histone-like proteins nor show complex packaging into chromosome-like structures, as observed in eukaryotes. Unlike mitotic cell divisions observed in eukaryotic cells, mitochondria and chloroplasts...
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...
01:29Non-nuclear Inheritance
Most DNA resides in the nucleus of a cell. However, some organelles in the cell cytoplasm—such as chloroplasts and mitochondria—also have their own DNA. These organelles replicate their DNA independently of the nuclear DNA of the cell in which they reside. Non-nuclear inheritance describes the inheritance of genes from structures other than the nucleus.
02:38Asexual Reproduction
Asexual reproduction allows plants to reproduce without growing flowers, attracting pollinators, or dispersing seeds. Offspring are genetically identical to the parent and produced without the fusion of male and female gametes.