Intraspecific variation and plasticity in mitochondrial oxygen binding affinity as a response to environmental...

Area of Science:

• Physiology
• Evolutionary Biology
• Environmental Science

Background:

• Mitochondrial function is linked to aerobic performance and tolerance limits.
• Previous research focused on maximum mitochondrial capacity, overlooking oxygen kinetics.

Purpose of the Study:

• Investigate mitochondrial oxygen kinetics' role in local adaptation and thermal plasticity.
• Compare two Atlantic killifish subspecies (Fundulus heteroclitus) across temperature acclimation.

Main Methods:

• Measured mitochondrial O2 P50 (oxygen affinity) in two subspecies acclimated to 5, 15, and 33°C.
• Assessed whole-blood Hb O2-P50 to evaluate oxygen delivery differences.
• Correlated mitochondrial and blood oxygen kinetics with thermal tolerance.

Main Results:

• Southern subspecies showed lower mitochondrial O2 P50 (higher O2 affinity) than the northern subspecies.
• Thermal acclimation altered mitochondrial O2 P50 in both subspecies.
• No significant differences in whole-blood Hb O2-P50 were found between subspecies.

Conclusions:

• Mitochondrial oxygen kinetics, specifically O2 affinity, contribute to subspecies differences in aerobic performance and thermal tolerance.
• Mitochondrial O2 kinetics play a key role in species' adaptation to environmental change.
• Oxygen delivery via hemoglobin does not explain subspecies differences in thermal tolerance.