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Seed dispersal is the movement, spread or transport of
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
s away from the parent plant. Plants have limited mobility and rely upon a variety of
dispersal vector A dispersal vector is an agent of biological dispersal that moves a dispersal unit, or organism, away from its birth population to another location or population in which the individual will reproduce. These dispersal units can range from pollen to ...
s to transport their propagules, including both
abiotic
abiotic
vectors such as the wind and living (
biotic Biotics describe living or once living components of a community; for example organisms, such as animals and plants. Biotic may refer to: *Life, the condition of living organisms *Biology, the study of life *Biotic material, which is derived from l ...
) vectors like birds. Seeds can be dispersed away from the parent plant individually or collectively, as well as dispersed in both space and time. The patterns of seed dispersal are determined in large part by the dispersal mechanism and this has important implications for the demographic and genetic structure of plant populations, as well as
migration Migration, migratory, or migrate may refer to: Human migration * Human migration, physical movement by humans from one region to another ** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
patterns and species interactions. There are five main modes of seed dispersal:
gravity Gravity (), or gravitation, is a by which all things with or —including s, s, , and even —are attracted to (or ''gravitate'' toward) one another. , gravity gives to s, and the causes the s of the oceans. The gravitational attracti ...

gravity
, wind, ballistic, water, and by animals. Some plants are
serotinous Serotiny in botany simply means 'following' or 'later'. In the case of serotinous flowers, it means flowers which grow following the growth of leaves, or even more simply, flowering later in the season than is customary with allied species. Havi ...
and only disperse their seeds in response to an environmental stimulus. Dispersal involves the letting go or detachment of a diaspore from the main parent plant.


Benefits

Seed dispersal is likely to have several benefits for different plant species. First, seed survival is often higher away from the parent plant. This higher survival may result from the actions of density-dependent
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...
and seedling predators and
pathogens In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanism ...
, which often target the high concentrations of seeds beneath adults.
Competition Competition is a rivalry A rivalry is the state of two people or groups engaging in a lasting competitive relationship. Rivalry is the "against each other" spirit between two competing sides. The relationship itself may also be called "a ri ...
with adult plants may also be lower when seeds are transported away from their parent. Seed dispersal also allows plants to reach specific habitats that are favorable for survival, a hypothesis known as directed dispersal. For example, ''Ocotea endresiana'' (Lauraceae) is a tree species from Latin America which is dispersed by several species of birds, including the
three-wattled bellbird The three-wattled bellbird (''Procnias tricarunculatus'') is a Central American Bird migration, migratory bird of the cotinga family. The sexes are very dis-similar in appearance. The male has a white head and throat and the remaining plumage is c ...
. Male bellbirds perch on dead trees in order to attract mates, and often defecate seeds beneath these perches where the seeds have a high chance of survival because of high light conditions and escape from fungal pathogens. In the case of fleshy-fruited plants, seed-dispersal in animal guts (endozoochory) often enhances the amount, the speed, and the asynchrony of germination, which can have important plant benefits. Seeds dispersed by ants (
myrmecochory Myrmecochory ( (sometimes myrmechory); from grc, μύρμηξ, mýrmēks and ''khoreíā'' "circular dance") is seed dispersal Seed dispersal is the movement, spread or transport of seed A seed is an embryonic ''Embryonic'' is the twelf ...
) are not only dispersed short distances but are also buried underground by the ants. These seeds can thus avoid adverse environmental effects such as fire or drought, reach nutrient-rich microsites and survive longer than other seeds. These features are peculiar to myrmecochory, which may thus provide additional benefits not present in other dispersal modes. Finally, at another scale, seed dispersal may allow plants to colonize vacant habitats and even new geographic regions. Dispersal distances and deposition sites depend on the movement range of the disperser, and longer dispersal distances are sometimes accomplished through
diplochory Diplochory, also known as “secondary dispersal”, “indirect dispersal” or "two-phase dispersal", is a seed dispersal mechanism in which a plant's seed is moved sequentially by more than one dispersal mechanism or vector. The significance of ...
, the sequential dispersal by two or more different dispersal mechanisms. In fact, recent evidence suggests that the majority of seed dispersal events involves more than one dispersal phase.


Types

Seed dispersal is sometimes split into ''autochory'' (when dispersal is attained using the plant's own means) and ''allochory'' (when obtained through external means).


Long distance

Long-distance seed dispersal (LDD) is a type of spatial dispersal that is currently defined by two forms, proportional and actual distance. A plant's fitness and survival may heavily depend on this method of seed dispersal depending on certain environmental factors. The first form of LDD, proportional distance, measures the percentage of seeds (1% out of total number of seeds produced) that travel the farthest distance out of a 99% probability distribution. The proportional definition of LDD is in actuality a descriptor for more extreme dispersal events. An example of LDD would be that of a plant developing a specific dispersal vector or morphology in order to allow for the dispersal of its seeds over a great distance. The actual or absolute method identifies LDD as a literal distance. It classifies 1 km as the threshold distance for seed dispersal. Here, threshold means the minimum distance a plant can disperse its seeds and have it still count as LDD. There is a second, unmeasurable, form of LDD besides proportional and actual. This is known as the non-standard form. Non-standard LDD is when seed dispersal occurs in an unusual and difficult-to-predict manner. An example would be a rare or unique incident in which a normally-lemur-dependent deciduous tree of Madagascar was to have seeds transported to the coastline of South Africa via attachment to a mermaid purse (egg case) laid by a shark or skate. A driving factor for the evolutionary significance of LDD is that it increases plant fitness by decreasing neighboring plant competition for offspring. However, it is still unclear today as to how specific traits, conditions and trade-offs (particularly within short seed dispersal) effect LDD evolution.


Autochory

Autochorous plants disperse their seed without any help from an external vector, as a result this limits plants considerably as to the distance they can disperse their seed. Two other types of autochory not described in detail here are blastochory, where the stem of the plant crawls along the ground to deposit its seed far from the base of the plant, and herpochory (the seed crawls by means of
trichome Trichomes ( or ), from the Greek language, Greek τρίχωμα (trichōma) meaning "hair", are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, gland ...
s and changes in humidity).


Gravity

''Barochory'' or the plant use of gravity for dispersal is a simple means of achieving seed dispersal. The effect of
gravity Gravity (), or gravitation, is a by which all things with or —including s, s, , and even —are attracted to (or ''gravitate'' toward) one another. , gravity gives to s, and the causes the s of the oceans. The gravitational attracti ...

gravity
on heavier fruits causes them to fall from the plant when ripe. Fruits exhibiting this type of dispersal include
apple An apple is an edible fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this fie ...

apple
s,
coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family (biology), family (Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, t ...

coconut
s and
passionfruit ''Passiflora edulis,'' commonly known as passion fruit, is a vine A vine (Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication ...

passionfruit
and those with harder shells (which often roll away from the plant to gain more distance). Gravity dispersal also allows for later transmission by water or animal.


Ballistic dispersal

''Ballochory'' is a type of dispersal where the seed is forcefully ejected by
explosive dehiscence Dehiscence is the splitting of a mature plant structure along a built-in line of weakness in order to release its contents. This is common among fruit In botany Botany, also called , plant biology or phytology, is the science of plan ...
of the fruit. Often the force that generates the explosion results from
turgor pressure Turgor pressure is the force within the cell that pushes the plasma membrane cell membrane vs. Prokaryotes A prokaryote () is a single-celled organism A unicellular organism, also known as a single-celled organism, is an organism In b ...
within the fruit or due to internal tensions within the fruit. Some examples of plants which disperse their seeds autochorously include: '' Arceuthobium spp.'', ''
Cardamine hirsuta ''Cardamine hirsuta'', commonly called hairy bittercress, is an annual or biennial species of plant in the family Brassicaceae, and is edible as a salad green. It is common in moist areas around the world. Description Depending on the climate ...

Cardamine hirsuta
'', '' Ecballium spp.'', ''
Euphorbia heterophylla ''Euphorbia heterophylla'', also known under the common names of (Mexican) fireplant, painted euphorbia, Japanese poinsettia, desert poinsettia, wild poinsettia, fire on the mountain, paintedleaf, painted spurge, milkweed, and kaliko plant, is a ...

Euphorbia heterophylla
'', '''', ''
Impatiens spp. ''Impatiens'' is a genus of more than 1,000 species of flowering plants, widely distributed throughout the Northern Hemisphere and the tropics. Together with the genus ''Hydrocera'' (1 species), ''Impatiens'' make up the family (biology), family ...

Impatiens spp.
'', ''
Sucrea spp ''Sucrea'' is a genus of Brazilian plants in the Poaceae, grass family. ;Species # ''Sucrea maculata'' Soderstr. - Rio de Janeiro (state), Rio de Janeiro, Espírito Santo # ''Sucrea monophylla'' Soderstr. - Bahia # †''Sucrea sampaiana'' (Hitchc ...
'', '' Raddia spp.'' and others. An exceptional example of ballochory is ''
Hura crepitans ''Hura crepitans'', the sandbox tree, also known as possumwood and jabillo, is an evergreen tree of the spurge family (Euphorbiaceae The Euphorbiaceae, the spurge ''Euphorbia'' is a very large and diverse genus Genus (plural genera) is ...

Hura crepitans
''—this plant is commonly called the dynamite tree due to the sound of the fruit exploding. The explosions are powerful enough to throw the seed up to 100 meters.
Witch hazel Witch-hazels or witch hazels (''Hamamelis'') are a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining ( ...
uses ballistic dispersal without explosive mechanisms by simply squeezing the seeds out at 28 mph.


Allochory

Allochory refers to any of many types of seed dispersal where a vector or secondary agent is used to disperse seeds. These vectors may include wind, water, animals or others.


Wind

Wind dispersal (''anemochory'') is one of the more primitive means of dispersal. Wind dispersal can take on one of two primary forms: seeds or fruits can float on the breeze or, alternatively, they can flutter to the ground. The classic examples of these dispersal mechanisms, in the temperate northern hemisphere, include
dandelions ''Taraxacum'' () is a large genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxono ...

dandelions
, which have a feathery pappus attached to their fruits (
achenes An achene (; Greek ἀ, ''a'', privative + χαίνειν, ''chainein'', to gape; also sometimes called akene and occasionally achenium or achenocarp) is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocar ...
) and can be dispersed long distances, and
maple ''Acer'' is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining (Circumscription (taxonomy), circumscr ...

maple
s, which have winged fruits ( samaras) that flutter to the ground. An important constraint on wind dispersal is the need for abundant seed production to maximize the likelihood of a seed landing in a site suitable for
germination Germination is the process by which an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biolog ...

germination
. Some wind-dispersed plants, such as the dandelion, can adjust their morphology in order to increase or decrease the rate of germination. There are also strong evolutionary constraints on this dispersal mechanism. For instance, Cody and Overton (1996) found that species in the Asteraceae on islands tended to have reduced dispersal capabilities (i.e., larger
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
mass Mass is the quantity Quantity is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", "less", or "equal", or by assigning a numerical value ...
and smaller pappus) relative to the same species on the mainland. Also, '' Helonias bullata'', a species of perennial herb native to the United States, evolved to utilize wind dispersal as the primary seed dispersal mechanism; however, limited wind in its habitat prevents the seeds to successfully disperse away from its parents, resulting in clusters of population. Reliance on wind dispersal is common among many
weed A weed is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration, can late ...

weed
y or
ruderal A ruderal species is a plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert light energy into chemical energy that, through cellular respiration ...
species. Unusual mechanisms of wind dispersal include
tumbleweed A tumbleweed is a structural part of the above-ground anatomy of a number of species of plant Plants are predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transformation, convert ...
s, where the entire plant (except for the roots) is blown by the wind. ''
Physalis ''Physalis'' (, , , , from φυσαλλίς ''phusallís'' "bladder") is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific stu ...

Physalis
'' fruits, when not fully ripe, may sometimes be dispersed by wind due to the space between the fruit and the covering calyx which acts as an air bladder.


Water

Many
aquatic Aquatic means relating to water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphe ...
(water dwelling) and some
terrestrial Terrestrial refers to things related to land Land is the solid surface of Earth that is not permanently submerged in water. Most but not all land is situated at elevations above sea level (variable over geologic time frames) and consists main ...
(land dwelling) species use ''hydrochory'', or seed dispersal through water. Seeds can travel for extremely long distances, depending on the specific mode of
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...

water
dispersal; this especially applies to fruits which are waterproof and float on water. The is an example of such a plant. Water lilies' flowers make a
fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

fruit
that floats in the water for a while and then drops down to the bottom to take
root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + φυτά ''phutá'' 'plants'), form a large grou ...

root
on the floor of the
pond A pond is an area filled with water, either natural or Artificiality, artificial, that is smaller than a lake. Ponds are small bodies of freshwater with shallow and still water, marsh, and aquatic plants.Clegg, J. (1986). Observer's Book of ...

pond
. The seeds of
palm tree The Arecaceae is a family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territory, typica ...

palm tree
s can also be dispersed by water. If they grow near
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
s, the seeds can be transported by
ocean current An ocean current is a continuous, directed movement of sea water generated by a number of forces acting upon the water, including wind Wind is the natural movement of air or other gases relative to a planet's surface. Wind occurs on a rang ...
s over long distances, allowing the seeds to be dispersed as far as other
continent A continent is any of several large landmass A landmass, or land mass, is a large region In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of th ...

continent
s.
Mangrove A mangrove is a shrub A shrub (often called a bush) is a small- to medium-sized perennial A perennial plant or simply perennial is a plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Pl ...

Mangrove
trees grow directly out of the water; when their seeds are ripe they fall from the
tree In botany, a tree is a perennial plant with an elongated Plant stem, stem, or trunk (botany), trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only wood plants with se ...

tree
and grow
root In vascular plant Vascular plants (from Latin ''vasculum'': duct), also known as Tracheophyta (the tracheophytes , from Greek τραχεῖα ἀρτηρία ''trācheia artēria'' 'windpipe' + φυτά ''phutá'' 'plants'), form a large grou ...

root
s as soon as they touch any kind of soil. During low tide, they might fall in soil instead of water and start growing right where they fell. If the water level is high, however, they can be carried far away from where they fell. Mangrove trees often make little
island An island (or isle) is an isolated piece of habitat that is surrounded by a dramatically different habitat, such as water. Very small islands such as emergent land features on atoll An atoll (), sometimes known as a coral atoll, i ...

island
s as dirt and detritus collect in their roots, making little bodies of land.


Animals: epi- and endozoochory

Animals can disperse plant seeds in several ways, all named ''zoochory''. Seeds can be transported on the outside of vertebrate animals (mostly mammals), a process known as ''epizoochory''. Plant species transported externally by animals can have a variety of adaptations for dispersal, including adhesive mucus, and a variety of hooks, spines and barbs. A typical example of an epizoochorous plant is ''Trifolium angustifolium'', a species of
Old World The Old World consists of Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% o ...
clover Clover or trefoil are common names for plants of the genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of naming, defining ( ...

clover
which adheres to animal fur by means of stiff
hair Hair is a protein filament In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Ph ...

hair
s covering the
seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips released on October 13, 2009, on Warner Bros. Records, Warner Bros. The band's first double album, it was released to generally positi ...

seed
. Epizoochorous plants tend to be herbaceous plants, with many representative species in the families
Apiaceae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants The flowering plants, also known as Angiospermae (), or Magnoliophyta (), are the most diverse group of land plants The Embryophyta () or land plants are the most fami ...

Apiaceae
and
Asteraceae The family (biology), family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the Order (biology), order Asterales. Commonly referred to as the aster, daisy, composite, o ...

Asteraceae
. However, epizoochory is a relatively rare dispersal syndrome for plants as a whole; the percentage of plant species with seeds adapted for transport on the outside of animals is estimated to be below 5%. Nevertheless, epizoochorous transport can be highly effective if seeds attach to wide-ranging animals. This form of seed dispersal has been implicated in rapid plant migration and the spread of invasive species. Seed dispersal via ingestion by vertebrate animals (mostly birds and mammals), or ''endozoochory'', is the dispersal mechanism for most tree species. Endozoochory is generally a coevolved mutualistic relationship in which a plant surrounds seeds with an edible, nutritious
fruit In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...
as a good food resource for animals that consume it. Such plants may advertise the presence of food resource by using colour. Birds and mammals are the most important seed dispersers, but a wide variety of other animals, including turtles, fish, and insects (e.g. tree wētā and ), can transport viable seeds. The exact percentage of tree species dispersed by endozoochory varies between
habitats In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organism ...

habitats
, but can range to over 90% in some tropical rainforests. Seed dispersal by animals in tropical rainforests has received much attention, and this interaction is considered an important force shaping the ecology and evolution of vertebrate and tree populations. In the tropics, large animal seed dispersers (such as
tapirs A tapir ( ) is a large, herbivorous A herbivore is an animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system that ...
,
chimpanzees The chimpanzee (''Pan troglodytes''), also known simply as chimp, is a species of Hominidae, great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. The chimpanzee and ...
,
black-and-white colobus Black-and-white colobuses (or colobi) are Old World monkey Old World monkey is the common English name for a family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relat ...

black-and-white colobus
,
toucans Toucans (, ) are members of the Neotropical realm, Neotropical near passerine bird Family (biology), family Ramphastidae. The Ramphastidae are most closely related to the Capitonidae, American barbets. They are brightly marked and have large, of ...
and
hornbills Hornbills (Bucerotidae) are a family In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social territo ...

hornbills
) may disperse large seeds with few other seed dispersal agents. The extinction of these large
frugivore A frugivore is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance and ...
s from poaching and habitat loss may have negative effects on the tree populations that depend on them for seed dispersal and reduce genetic diversity. A variation of endozoochory is regurgitation rather than all the way through the digestive tract. The seed dispersal by birds and other mammals are able to attach themselves to the feathers and hairs of these vertebrates, which is their main method of dispersal. Seed dispersal by ants (''
myrmecochory Myrmecochory ( (sometimes myrmechory); from grc, μύρμηξ, mýrmēks and ''khoreíā'' "circular dance") is seed dispersal Seed dispersal is the movement, spread or transport of seed A seed is an embryonic ''Embryonic'' is the twelf ...
'') is a dispersal mechanism of many shrubs of the southern hemisphere or understorey herbs of the northern hemisphere. Seeds of myrmecochorous plants have a lipid-rich attachment called the
elaiosome Elaiosomes ( grc, ἔλαιον ''élaion'' "oil" + ''sóma'' "body") are fleshy structures that are attached to the seed A seed is an embryonic ''Embryonic'' is the twelfth studio album by experimental rock band the Flaming Lips releas ...
, which attracts ants. Ants carry such seeds into their colonies, feed the elaiosome to their larvae and discard the otherwise intact seed in an underground chamber. Myrmecochory is thus a coevolved mutualistic relationship between plants and seed-disperser ants. Myrmecochory has independently evolved at least 100 times in flowering plants and is estimated to be present in at least 11 000 species, but likely up to 23 000 or 9% of all species of flowering plants. Myrmecochorous plants are most frequent in the fynbos vegetation of the Cape Floristic Region of South Africa, the kwongan vegetation and other dry habitat types of Australia, dry forests and grasslands of the Mediterranean region and northern temperate forests of western Eurasia and eastern North America, where up to 30–40% of understorey herbs are myrmecochorous. Seed dispersal by ants is a mutualistic relationship and benefits both the ant and the plant. Seed predators, which include many rodents (such as squirrels) and some birds (such as jays) may also disperse seeds by hoarding the seeds in hidden caches. The seeds in caches are usually well-protected from other seed predators and if left uneaten will grow into new plants. In addition, rodents may also disperse seeds via seed spitting due to the presence of
secondary metabolites Secondary metabolites, also called specialised metabolite In biochemistry Biochemistry or biological chemistry, is the study of chemical process In a scientific Science (from the Latin Latin (, or , ) is a classical language bel ...
in ripe fruits. Finally, seeds may be secondarily dispersed from seeds deposited by primary animal dispersers, a process known as
diplochory Diplochory, also known as “secondary dispersal”, “indirect dispersal” or "two-phase dispersal", is a seed dispersal mechanism in which a plant's seed is moved sequentially by more than one dispersal mechanism or vector. The significance of ...
. For example, dung beetles are known to disperse seeds from clumps of feces in the process of collecting dung to feed their larvae. Other types of zoochory are ''chiropterochory'' (by bats), ''malacochory'' (by molluscs, mainly terrestrial snails), ''ornithochory'' (by birds) and ''saurochory'' (by non-bird sauropsids). Zoochory can occur in more than one phase, for example through ''diploendozoochory'', where a primary disperser (an animal that ate a seed) along with the seeds it is carrying is eaten by a predator that then carries the seed further before depositing it.


Humans

Dispersal by humans ('' anthropochory'') used to be seen as a form of dispersal by animals. Its most widespread and intense cases account for the planting of much of the land area on the planet, through agriculture. In this case, human societies form a long-term relationship with plant species, and create conditions for their growth. Recent research points out that human dispersers differ from animal dispersers by having a much higher mobility, based on the technical means of human transport. On the one hand, dispersal by humans also acts on smaller, regional scales and drives the dynamics of existing biological
population Population typically refers the number of people in a single area whether it be a city or town, region, country, or the world. Governments typically quantify the size of the resident population within their jurisdiction by a process called a ...

population
s. On the other hand, dispersal by humans may act on large geographical scales and lead to the spread of
invasive species An invasive species is an introduced organism that becomes overpopulated and negatively alters its new environment. Although their spread can have beneficial aspects, invasive species adversely affect the invaded habitat Ibex in an ...
. Humans may disperse seeds by many various means and some surprisingly high distances have been repeatedly measured. Examples are: dispersal on human clothes (up to 250 m), on shoes (up to 5 km), or by cars (regularly ~ 250 m, singles cases > 100 km). Seed dispersal by cars can be a form of unintentional transport of seeds by humans, which can reach far distances, greater than other conventional methods of dispersal. Cars that carry soil are able to contain viable seeds, a study by Dunmail J. Hodkinson and Ken Thompson found that the most common seeds that were carried by vehicle were (''Plantago major''), (''Poa annua''), rough meadow grass (''Poa trivialis''),
stinging nettle ''Urtica dioica'', often known as common nettle, stinging nettle (although not all plants of this species sting) or nettle leaf, or just a nettle or stinger, is a herbaceous Herbaceous plants are vascular plants that have no persistent wood ...

stinging nettle
] (''Urtica dioica'') and Matricaria discoidea, wild chamomile (''Matricaria discoidea''). Deliberate seed dispersal also occurs as seed bombing. This has risks, as unsuitable provenance may introduce genetically unsuitable plants to new environments.


Consequences

Seed dispersal has many consequences for the ecology and evolution of plants. Dispersal is necessary for species migrations, and in recent times dispersal ability is an important factor in whether or not a species transported to a new habitat by humans will become an invasive species. Dispersal is also predicted to play a major role in the origin and maintenance of species diversity. For example, myrmecochory increased the rate of diversification more than twofold in plant groups in which it has evolved because myrmecochorous lineages contain more than twice as many species as their non-myrmecochorous sister groups. Dispersal of seeds away from the parent organism has a central role in two major theories for how biodiversity is maintained in natural ecosystems, the Janzen-Connell hypothesis and recruitment limitation. Seed dispersal is essential in allowing forest migration of flowering plants. It can be influenced by the production of different fruit morphs in plants, a phenomenon known as heterocarpy.Gardocki, M. E., Zablocki, H., El-Keblawy, A., & Freeman, D. C. (2000). Heterocarpy in Calendula micrantha (Asteraceae): The effects of competition and availability of water on the performance of offspring from different fruit morphs. Evolutionary Ecology Research. 2(6):701-718 These fruit morphs are different in size and shape and have different dispersal ranges, which allows seeds to be dispersed for varying distances and adapt to different environments. In addition, the speed and direction of wind are highly influential in the dispersal process and in turn the deposition patterns of floating seeds in the stagnant water bodies. The transportation of seeds is led by the wind direction. This effects colonization situated on the banks of a river or to wetlands adjacent to streams relative to the distinct wind directions. The wind dispersal process can also affect connections between water bodies. Essentially, wind plays a larger role in the dispersal of waterborne seeds in a short period of time, days and seasons, but the ecological process allows the process to become balanced throughout a time period of several years. The time period of which the dispersal occurs is essential when considering the consequences of wind on the ecological process.


See also

*
Biological dispersal Biological dispersal refers to both the movement of individuals (animal Animals (also called Metazoa) are multicellular A multicellular organism is an organism In biology, an organism () is any organic, life, living system ...
* Biantitropical distribution *
Disturbance (ecology) In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms ...
*
Dormancy Dormancy is a period in an organism's life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the pr ...
– "dispersal in time" *
Gene flow In population genetics Population genetics is a subfield of that deals with genetic differences within and between s, and is a part of . Studies in this branch of examine such phenomena as , , and . Population genetics was a vital ingredient ...

Gene flow
*
Habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biop ...
*
Island hopping Leapfrogging, also known as island hopping, was a military strategy employed by the Allies of World War II, Allies in the Pacific War against the Empire of Japan during World War II. The key idea is to bypass heavily fortified enemy islands in ...

Island hopping
*
Landscape ecology Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizatio ...
*
Metapopulation A metapopulation consists of a group of spatially separated populations of the same species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodi ...

Metapopulation
*
Oceanic dispersal Oceanic dispersal is a type of biological dispersal Biological dispersal refers to both the movement of individuals (animal Animals (also called Metazoa) are organisms that form the Animalia. With few exceptions, animals , , are ...
*
Population ecology Population ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment (biophysical), environment, such as birth rate, birth and death rates, and by immigration and ...
*
Seed dispersal syndrome Seed dispersal syndromes are morphological characters of seeds correlated to particular seed dispersal agents.Clobert, J., Le Galliard, J.F., Cote, J., Meylan, S. & Massot, M. (2009). Informed dispersal, heterogeneity in animal dispersal syndromes a ...


References


Further reading

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External links


Fruit and seed dispersal images at bioimages.vanderbilt.edu
* ttps://www.youtube.com/watch?v=BaTFV0Jo26Y Secondary metabolites promote seed dispersal {{Authority control Seeds Ecology Articles containing video clips