Testing for ecological limitation of diversification: a case study using parasitic plants

Area of Science:

• Evolutionary Biology
• Ecology
• Phylogenetics

Background:

• Phylogenetic diversity imbalances can arise from varying diversification rates or diversity limits.
• Parasitic plants often show reduced diversity compared to their non-parasitic relatives.

Purpose of the Study:

• To develop a method for differentiating between diversification rates and limits as causes of phylogenetic imbalance.
• To investigate the drivers of diversity asymmetry in parasitic plant lineages.

Main Methods:

• Sister-taxon comparisons to assess diversity differences between parasitic and autotrophic plant lineages.
• Correlation analysis between clade age and clade diversity using age estimates.
• Phylogenetic model fitting on well-sampled phylogenies, specifically the Ericaceae family.

Main Results:

• Parasitic plant lineages are consistently less diverse than their autotrophic sister lineages.
• Parasitic plant diversity shows no significant correlation with lineage age, unlike non-parasitic lineages.
• Model fitting for the Ericaceae pair suggests ecological limitation in parasitic Monotropoideae and unconstrained diversification in autotrophic Arbutoideae.

Conclusions:

• Differences in diversity between parasitic and autotrophic plants may result from a combination of ecological limitation and exponential diversification.
• Sister-taxon comparisons and phylogenetic modeling offer a robust approach to understanding lineage diversity asymmetry.