Changing climate mediates sapsucker (Aves: Sphyrapicus) hybrid zone movement

Area of Science:

• Evolutionary Biology
• Ornithology
• Climate Change Ecology

Background:

• Hybrid zones offer insights into climate's role in reproductive isolation and species adaptation.
• The Red-naped (Sphyrapicus nuchalis) and Red-breasted (Sphyrapicus ruber) sapsucker hybrid zone in the Pacific Northwest has been studied for over a century.
• Museum specimens and historical data provide a baseline for tracking phenotypic shifts.

Purpose of the Study:

• To investigate how climate change impacts the distribution and overlap of Red-naped and Red-breasted sapsuckers.
• To predict the future movement and potential contraction of their hybrid zone under various climate scenarios.
• To understand the implications of these changes for reproductive isolation and genetic introgression.

Main Methods:

• Utilized museum collection data to infer historical phenotypic shifts.
• Employed species distribution models (Random Forests) to predict historical, current, and future distributions.
• Quantified climate change effects on sapsucker distributions and hybrid zone dynamics.

Main Results:

• Observed distribution shifts over the past 100 years are strongly linked to climate change.
• Future climate scenarios predict continued expansion of Red-breasted Sapsuckers and substantial contraction of Red-naped Sapsuckers.
• The climate niche of the hybrid zone is predicted to disappear, potentially reducing genetic introgression.

Conclusions:

• Climate change is a significant driver of sapsucker distribution shifts and hybrid zone dynamics.
• Future climate change may lead to decreased overlap between the two sapsucker species.
• The predicted disappearance of the hybrid zone's climate niche could substantially reduce gene flow, impacting evolutionary trajectories.