Dispersal Ant Species

Ants are often involved in interactions with other species. Myrmecochory is the dispersal of seeds by ants. Plants species in this interaction have elaiosomes on their seeds that are lipid rich and act as a reward for the ant. Ant mediated seed dispersal are widespread and have evolved independently several times. It is mostly found in herbs in the northern hemisphere and sclerophyllous scrubs on low nutrient soils in Australia and South Africa. The number of effective seed dispersing ant species is around 100. Myrmecochory is asymmetrical; the interaction is obligate for the plant, but not for the ant.

Keywords: ant, asymmetric interactions, evolution, mutualism, myrmecochory, seed dispersal

Introduction

Ants interact with plants in many

The mode of dispersal is an important trait in a plant and vital for its fitness. The exploitation of new sites and reduced competition with closely related individuals are the general benefits with seed dispersal (Lengyel et al., 2010). There are several hypotheses about the specific benefits experienced from myrmecochory for the plant. Directed dispersal is one of them; the ants move the seeds to a place more suitable for the seed than if it were distributed at random, maybe because of high nutrient levels close to the ant nest or specific conditions in the nest. Predator avoidance is another; when the ants carry the seeds away and maybe bury them, seed predators will have a smaller chance of finding them. A third hypothesis is distance dispersal, which reduces competition. Fire avoidance can also be a benefit in some regions. Because the ants bury the seed they will have a greater possibility of surviving a fire (Giladi, 2006). Giladi, 2006 made a meta analysis of studies concerning these different hypothesis. Most of the studies used in the analysis found support for more than one of the hypotheses. The different advantages of myrmecochory are not excluding each other. There might be a positive interaction between the different benefits. An example is that, it was found that the positive effect of escaping predators and distance dispersal were only apparent after fire for a specific myrmecochorous

If the ants were predating on the seeds it would be an advantage for the plant to develop methods preventing this. Many ant species might be both predators and dispersers at the same time and will not fit the term entirely mutualistic or entirely antagonistic (Levey and Byrne, 1993). Certain conditions need to be fulfilled for ants to be beneficial seed disperser. They have to be present in high enough numbers and the seeds fitness should be directly influenced by being picked up by an ant. Seed traits that can manipulate the ants would then be very favourable (Lengyel et al.,