A latitudinal phylogeographic diversity gradient in birds

Area of Science:

• Evolutionary Biology
• Biodiversity Science
• Ornithology

Background:

• High species diversity in the tropics is traditionally linked to long-term evolutionary dynamics.
• Intraspecific (within-species) genetic divergence is a potential early driver of latitudinal diversity gradients, but is poorly understood at large scales.
• Previous phylogeographic studies were limited to restricted geographic areas.

Purpose of the Study:

• To investigate if population-level diversification processes mirror large-scale latitudinal gradients in species diversity.
• To assess the role of intraspecific genetic diversity in shaping biodiversity patterns across hemispheres.
• To determine if ecological and life-history factors explain observed phylogeographic structures.

Main Methods:

• Collected genetic data from 210 New World bird species across a wide latitudinal range.
• Applied comparative phylogeography to analyze genetic variation and population divergence.
• Quantified phylogeographic diversity metrics and examined their relationship with latitude.

Main Results:

• Species at lower latitudes exhibited significantly higher intraspecific phylogeographic diversity compared to higher-latitude species.
• Evidence suggests greater persistence of genetic diversity in tropical populations.
• Species ecology, life history, and habitat explained minimal variation in phylogeographic structure.

Conclusions:

• Latitudinal gradients in species richness may originate, in part, from population-level diversification processes.
• Results support hypotheses linking biodiversity gradients to evolutionary age and environmental stability.
• Large-scale comparative phylogeography reveals connections between intraspecific processes and broad biodiversity patterns.