Contrasting biogeographic and diversification patterns in two Mediterranean-type ecosystems.

Area of Science:

• Evolutionary Biology
• Biogeography
• Plant Systematics

Background:

• Mediterranean regions host significant plant biodiversity (20% of known vascular plants) on <5% of land.
• The Cape Floristic Region and Mediterranean Basin are key biodiversity hotspots with limited comparative evolutionary studies.
• The Hyacinthaceae family is a predominant and diverse group in both regions.

Purpose of the Study:

• To investigate the biogeographic and diversification processes shaping plant evolution in the Cape and Mediterranean Basin.
• To understand the historical relationships between these two major Mediterranean biodiversity hotspots.
• To analyze the evolutionary history of the Hyacinthaceae family in these regions.

Main Methods:

• Phylogenetic analysis using a large plastid data set for the Hyacinthaceae family.
• Application of state-of-the-art biogeographic and diversification methods.
• Comparative evolutionary analysis of plant families in Mediterranean regions.

Main Results:

• Hyacinthaceae originated in sub-Saharan Africa around the Paleocene-Eocene boundary.
• Both the Cape and Mediterranean Basin exhibit high diversification rates but possess contrasting biogeographic histories.
• The Cape's diversity is linked to sub-Saharan Africa; the Mediterranean Basin's diversification was isolated by Saharan aridification.

Conclusions:

• The Mediterranean Basin significantly contributed to the diversity of Northern Europe and the Middle East post-isolation.
• The Cape acted as a biogeographical 'cul-de-sac' with limited outward dispersal to sub-Saharan Africa.
• The study provides a framework for understanding evolutionary histories in major plant biodiversity repositories.