Time Explains Regional Richness Patterns within Clades More Often than Diversification Rates or Area

Area of Science:

• Ecology
• Evolutionary Biology
• Biogeography

Background:

• Organisms inhabit multiple regions with varying species counts.
• Regional species richness is influenced by speciation, extinction, and dispersal rates.
• Potential drivers include colonization time, frequency, and diversification rates.

Purpose of the Study:

• To investigate the primary factors explaining regional species richness patterns.
• To test the influence of colonization time, colonization frequency, and diversification rates across diverse clades.
• To compare findings with existing literature on biodiversity patterns.

Main Methods:

• Analysis of species richness patterns in 15 diverse plant and animal clades.
• Statistical modeling to assess the explanatory power of time, area, and diversification rates.
• Systematic review of 15 additional relevant studies.

Main Results:

• Colonization time was the most significant factor explaining regional species richness in 13 out of 15 clades.
• Time explained 72% of the variance in species richness across regions.
• Region area was found to be relatively unimportant; time's importance increased with clade age and size.
• A systematic review supported time over diversification rates in 13 out of 14 comparable studies.

Conclusions:

• Colonization time is a major determinant of regional species richness patterns.
• Historical factors, particularly the timing of colonization, play a more critical role than regional attributes like area.
• Findings highlight the importance of temporal dynamics in understanding biodiversity gradients.