This paper shows that, contrary to long-held ideas, the intensity of competition (density of direct, physical spatial contests) differs little with latitude. However, the severity of competition (contests with a win/loss outcome, leading to the loser’s death) is much lower at the poles.
Barnes & Neutel (2016) examined competition for space between bryozoans (sessile, colonial, suspension feeding animals) and other encrusting life in coastal shallow waters across the globe. When one colony grows into contact with another, fierce battles take place resulting in either a winner and loser, or a tie.
The authors explain the shift towards less severe competition at the poles by looking at the taxonomic relatedness of the competitors. By far the most polar competition was between same-species competitors whereas the majority of lower latitude contests were between species of different families.
The results are important for our understanding of climate change effects. At the poles, only a few opportunistic species can cope with the severe disturbance of iceberg scour. They dominate in abundance, and hence the many intra-specific encounters. With increasingly frequent storms to be expected in tropical waters, this disturbance may also lead to more opportunistic species and less severe competition in the tropics.
Severity of seabed spatial competition decreases towards the poles
Barnes, D.K.A.; Neutel, A.M
Current Biology, 26 (8). R317-R318. 10.1016/j.cub.2016.03.012