Postprint version. Published in Biophysical Journal, Volume 58, Issue 2, August 1, 1990, pages 549-555.
The definitive version is available at https://doi.org/10.1016/S0006-3495(90)82398-5.
The relative numbers of North-seeking and South-seeking polarity types in natural populations of magnetotactic bacteria were determined at sites on the coast of Brazil. These sites were South of the geomagnetic equator and had upward geomagnetic inclinations of 1–12°. For upward inclinations >6°, South-seeking cells predominated over North-seeking cells by more than a factor of 10. For upward inclinations