Seed and pollen dispersal by animals: convergence in the ecology of contamination and sloppy harvest

Abstract

Seed dispersal and pollen movement by animals have very much in common, though we know so little of either that it is hard to be specific. The focus has been on animals at the fruit crop rather than the seed shadows that they generate (and the fate of those seeds), and on the animals that arrive at flowers rather than where they take the pollen obtained or whence came the pollen they are carrying. ‘Seed dispersal’ is a word that does not imply the fate of the seed; ‘pollination’ relates to the fate of the pollen grain, and therefore the two words are not of parallel meaning. In like manner, seeds (the zygote contained within, are different individuals from the parents while pollen is much more like the parent. The following areas are discussed with respect to how seed and pollen movement compare: ability of parent plant to assess success; gene flow; dependency of animals on seeds, pollen and bait; disruption by animal loss; secondary movements; fate of most seeds and pollen; syndromes; selection for maximization of movement; exclusion of ‘unwanted’ animals; adjustments to the needs of the animals; seeds and pollen as contaminants; necessity of dispersal and outcrossing. We need much more knowledge of what actually is happening in nature with seed and pollen shadows, and improved ability to think like a plant.