Does variation in genome sizes reflect adaptive or neutral processes? New clues from Passiflora

Area of Science:

• Genomic evolution
• Plant evolutionary biology
• Phylogenetics

Background:

• Genomic evolution presents a paradox with abundant repetitive DNA, often deemed non-functional.
• Understanding genome size (GS) variation's role in adaptation versus neutral processes is crucial.

Purpose of the Study:

• Investigate adaptive vs. neutral genome size (GS) variation in 50 Passiflora species.
• Compare GS and flower diameter (FD) across Passiflora and Decaloba subgenera.
• Examine evolutionary tempo, mode, and trait correlations.

Main Methods:

• Comparative phylogenetic analyses.
• Phylogenetic tree construction for 50 Passiflora species.
• Estimation of genome size (GS) and flower diameter (FD).
• Inference of trait evolution and correlations using current and phylogenetically independent contrasts.

Main Results:

• Significant correlations found between GS and FD in the complete dataset and Passiflora subgenus.
• No significant correlations observed between GS and FD within the Decaloba subgenus.
• Evidence suggests adaptive evolution of GS in Passiflora.

Conclusions:

• Genome size (GS) evolution in Passiflora appears to be adaptive.
• A minimum genome size may constrain GS evolution and phenotypic plasticity.
• These findings offer insights into the drivers of genomic diversity in plants.