Seed dispersal syndrome
Similar to the term syndrome, a diaspore is a morphological functional unit of a seed for dispersal purposes.
[6] Characteristics for seed dispersal syndromes are commonly fruit colour, mass, and persistence.
Therefore, seed dispersal syndromes will evolve in a plant when the trait benefit outweighs the cost.
[10] For example, birds put strong selection pressure on seeds for colour of fruits because of their enhanced vision.
He describes the morphology of interactions between fruits and flowers, and classifies dispersal in invertebrates, fish, reptiles, birds, mammals, ants, wind, water and the plant itself.
They looked at bird-dispersal and mammal-dispersal and how the fruits differed in dispersal syndromes such as colour and size.
These scientists began the theory and ideas behind seed dispersal syndromes that are crucial to the evolution of reproduction in plants.
Common dispersal syndromes of anemochory are wing structures[8] and brown or dull coloured seeds without further rewards.
[8] Anemochory is commonly found in open habitats,[14] canopy trees,[10] and dry season deciduous forests.
Endozoochory syndromes have evolved to be ingested by animals and later bypassed in a new environment so the seed can germinate.
[16] Synzoochory should possess hard skins to protect seeds from damage of mouthparts; for example, sharp beaks on animals such as birds or turtles.
These syndromes are highly associated with animals that have fur,[13] while burrs would be lacking on seeds that are dispersed by reptiles because of their smooth skin.
[18] Animal-dispersed seeds ripen in rainy season when foraging activity is high, resulting in fleshy diaspores.
[2][10][12] Mammals consume fruits whole or in smaller pieces,[11] which explains the larger seed syndromes.
Common syndrome characteristics include small fleshy fruits with bright colours and without husks.
Birds have a weak sense of smell, therefore ornithochory syndromes would specialize more in colour than scent,[13] in comparison to mammalochory.
Jordano (1995) states that the evolution of fruit traits for seed dispersal success is only dependent on diameter.
Colour and olfaction are other common seed dispersal syndromes tested and discussed in scientific literature, with equivocal results.
[11] It is possible that there has not been enough research to test these characteristics or they do not play a role in seed dispersal syndromes.
The following are problems areas or directions research can continue on the study of seed dispersal syndromes.
[1][12] Research in this area would assist in the understanding of why particular dispersers are selected by plants to enhance reproductive success.
There is limited knowledge about the presence of elaisomes and ant behaviour affecting seed dispersal, and how ant-plant interactions evolved under various plant traits.
Micro and macroevolutionary processes are needed to determine the effects of biological dispersal of seeds.
[16] Using genetics could help clarify if these syndromes were formed at random or if they correspond to evolution of seed dispersal.
Understanding these relationships would clarify the confusion about seed dispersal syndromes and if they are true examples of evolution increasing plant reproductive success or if they have developed without selective pressures.
