A phylogenetic framework for evolutionary study of the nightshades (Solanaceae): a dated 1000-tip tree

Area of Science:

• Botany
• Evolutionary Biology
• Phylogenetics

Background:

• The Solanaceae family holds significant economic importance, encompassing crops like tomato and potato.
• Existing phylogenetic research lacks a robust, dated molecular framework for the entire family.
• This study addresses the need for a comprehensive evolutionary history of Solanaceae.

Purpose of the Study:

• To construct a densely-sampled, time-calibrated molecular phylogeny for the Solanaceae family.
• To investigate molecular divergence times and evolutionary relationships within Solanaceae.
• To provide a robust evolutionary framework for future research on the family.

Main Methods:

• Utilized a densely-sampled species-level phylogeny.
• Reviewed the fossil record to establish robust calibration points.
• Estimated divergence times using an uncorrelated relaxed molecular clock model.

Main Results:

• Strong support for previously identified clades within Solanaceae and relationships between major clades, especially within Solanum.
• The Tomato clade is sister to section Petota; the Regmandra clade is the first branching member of the Potato clade.
• Estimated divergence times: tomato and potato split ~8 Ma, Solanum and Capsicum ~19 Ma, Solanum and Nicotiana ~24 Ma.

Conclusions:

• The time-calibrated phylogeny represents a significant advancement in understanding Solanaceae evolution, including age estimates for the family.
• The chronogram includes 40% of known species and is highly resolved, representing one of the best-sampled angiosperm family phylogenies.
• Increased resolution and species sampling will facilitate numerous biological investigations using Solanaceae as a model system.