**Distribution and Diversity**:
– Over 3,000 plant species globally exhibit myrmecochory.
– Present in all major biomes on all continents except Antarctica.
– Common in Australian dry heath, sclerophyll woodlands, and South African fynbos.
– Found in mesic forests in temperate regions and tropical forests.
– Estimated 11,000 to 23,000 myrmecochorous plant species worldwide.
**Evolutionary History**:
– Myrmecochory evolved independently multiple times in various plant families.
– Over 100 separate origins of myrmecochory in 55 flowering plant families.
– Elaiosomes evolved from diverse parent tissues due to strong selective pressure.
– Myrmecochory is a prime example of convergent evolution.
– Promotes diversification in multiple flowering plant lineages.
**Ecology and Benefits**:
– Myrmecochory classified as a mutualism with various benefits for plants.
– Plants benefit from increased dispersal distance and directed dispersal to nutrient-rich sites.
– Costs include energy for diaspore provision and protection from ant predation.
– Few studies on benefits to ants participating in myrmecochory.
– Combination of factors contributes to the viability of this mutualistic interaction.
**Dispersal Distance and Directed Dispersal**:
– Increasing dispersal distance reduces seed mortality from density-dependent effects.
– Ants transport seeds up to 180m, with an average of less than 2m.
– Many myrmecochores exhibit diplochory for increased dispersal distance.
– Ballistic dispersal distance can exceed ant transport in some cases.
– Ants disperse seeds to nutrient-rich or protected microsites for better germination.
**Threats and Invasive Species**:
– Argentine ant displaces native ant populations.
– Breakdown in myrmecochory mutualism due to invasions.
– Invasive ants like red fire ant can maintain seed dispersal.
– European fire ant acts as a high-quality disperser.
– Myrmecochorous plants can invade ecosystems, and native ants may aid spread of myrmecochorous invaders.
Myrmecochory (/mɜːrmɪˈkɒkɔːri/ (sometimes myrmechory); from Ancient Greek: μύρμηξ, romanized: mýrmēks ("ant") and χορεία khoreíā ("circular dance") is seed dispersal by ants, an ecologically significant ant–plant interaction with worldwide distribution. Most myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acids, or other nutrients that are attractive to ants. The seed with its attached elaiosome is collectively known as a diaspore. Seed dispersal by ants is typically accomplished when foraging workers carry diaspores back to the ant colony, after which the elaiosome is removed or fed directly to ant larvae. Once the elaiosome is consumed, the seed is usually discarded in underground middens or ejected from the nest. Although diaspores are seldom distributed far from the parent plant, myrmecochores also benefit from this predominantly mutualistic interaction through dispersal to favourable locations for germination, as well as escape from seed predation.
