When It's All Take And No Give

In many relationships in nature, being needy is okay.

A new study finds that relationships in which one species depends heavily on another, but not vice-versa, help create community stability and promote biodiversity.

Researchers analyzed species that have evolved together in different parts of the world. One example was the bluetit Parus caeruleus (shown above), which robs the flowers of a Kniphofia hybrid for nectar in a garden in Denmark. The researchers found that such networks are dominated by weak, uneven interactions in which one partner depends strongly on another, while the other is only weakly dependent.

The study, led by Jordi Bascompte and Pedro Jordano from the Estación Biológica de Doñana, CSIC in Spain, was detailed in the April 21 issue of the journal Science.