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 nutritional composition of fruits. Frugivores can benefit or hinder fruit-producing plants by either dispersing or destroying their seeds through digestion. When both the fruit-producing plant and the frugivore benefit by fruit-eating behavior the interaction is a form of mutualism.

Frugivore seed dispersal

Seed dispersal In Spermatophyte plants, seed dispersal is the movement, spread or transport of seeds away from the parent plant. Plants have limited mobility and rely upon a variety of dispersal vectors to transport their seeds, including both abiotic vectors ...

is important for plants because it allows their progeny to move away from their parents over time. The advantages of seed dispersal may have led to the evolution of fleshy

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

s, which entice animals to consume them and move the plant's seeds from place to place. While many fruit-producing plant species would not disperse far without frugivores, their seeds can usually

germinate Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

even if they fall to the ground directly below their parent. Many types of animals are seed dispersers. Mammal and bird species represent the majority of seed-dispersing species. However, frugivorous tortoises, lizards, amphibians, and even fish also disperse seeds. For example, cassowaries are a keystone species because they spread fruit through digestion, many of the seeds of which will not grow unless they have been digested by the animal. While frugivores and fruit-producing plant species are present worldwide, there is some evidence that tropical forests have more frugivore seed dispersers than the temperate zones.

Ecological significance

Frugivore seed dispersal is a common phenomenon in many ecosystems. However, it is not a highly specific type of plant–animal interaction. For example, a single species of frugivorous bird may disperse fruits from several species of plants, or a few species of bird may disperse seeds of one plant species. This lack of specialization could be because fruit availability varies by season and year, which tends to discourage frugivore animals from focusing on just one plant species. Furthermore, different seed dispersers tend to disperse seeds to different habitats, at different abundances, and distances, depending on their behavior and numbers.

Plant adaptations to attract dispersers

There are a number of fruit characteristics that seem to be adaptive characteristics to attract frugivores. Animal-dispersed fruits may advertise their palatability to animals with bright colors and attractive smells (mimetic fruits). Fruit pulp is generally rich in water and

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...

s and low in

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

and

lipid Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids includ ...

s. However, the exact nutritional composition of fruits varies widely. The seeds of animal-dispersed fruits are often adapted to survive digestion by frugivores. For example, seeds can become more permeable to water after passage through an animal's gut. This leads to higher germination rates. Some mistletoe seeds even germinate inside the disperser's intestine.

Frugivore adaptations for fruit consumption

Many seed-dispersing animals have specialized digestive systems to process fruits, which leave seeds intact. Some bird species have shorter intestines to rapidly pass seeds from fruits, while some frugivorous bat species have longer intestines. Some seed-dispersing frugivores have short gut-retention times, and others can alter intestinal enzyme composition when eating different types of fruits.

Plant mechanisms to delay or deter frugivory

Since plants invest considerable energy into fruit production, many have evolved to encourage mutualist frugivores to consume their fruit for seed dispersal. Some have also evolved mechanisms to decrease consumption of fruits when unripe and from non-seed-dispersing predators. Predators and parasites of fruit include seed predators, insects, and microbial frugivores. Plants have developed both chemical and physical

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...

s: Physical deterrents: * Cryptic coloration (e.g. green fruits blend in with the plant leaves) *Unpalatable textures (e.g. thick skins made of anti-nutritive substances) *Resins and saps (e.g. prevent animals from swallowing) *Repellent substances, hard outer coats, spines, thorns Chemical deterrents: *Chemical deterrents in plants are called

secondary metabolite Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norma ...

s. Secondary metabolites are compounds produced by the plant that are not essential for the primary processes, such as growth and reproduction. Toxins might have evolved to prevent consumption by animals that disperse seeds into unsuitable habitats, to prevent too many fruits from being eaten per feeding bout by preventing too many seeds being deposited in one site, or to prevent digestion of the seeds in the gut of the animal. Secondary chemical defenses are divided into three categories:

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

-based,

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...

-based

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ...

s, and carbon-based phenolics. Examples of secondary chemical defenses in fruit: *

Capsaicin Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) ( or ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a chemical irritant for mammals, including humans, and produces a sensation of burnin ...

is a carbon-based

phenolic Phenolic is an adjective and a substantive (noun) that may apply to : * Phenol (or carbolic acid), a colorless crystalline solid and aromatic compound * Phenols, a class of chemical compounds that include phenol * Phenolic content in wine * Phenol ...

compound only found in plant genus ''

Capsicum ''Capsicum'' () is a genus of flowering plants in the nightshade family Solanaceae, native to the Americas, cultivated worldwide for their chili pepper or bell pepper fruit. Etymology and names The generic name may come from Latin , me ...

'' (chili and bell peppers). Capsaicin is responsible for the pungent, hot "flavor" of peppers and inhibits growth of microbes and invertebrates. *

Cyanogen Cyanogen is the chemical compound with the formula ( C N)2. It is a colorless and highly toxic gas with a pungent odor. The molecule is a pseudohalogen. Cyanogen molecules consist of two CN groups – analogous to diatomic halogen molecu ...

glycoside In chemistry, a glycoside is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycoside ...

s are nitrogen-based compounds and are found in 130 plant families, but not necessarily in the fruit of all the plants. It is specifically found in the red berries of the genus ''

Ilex ''Ilex'' (), or holly, is a genus of over 570 species of flowering plants in the family Aquifoliaceae, and the only living genus in that family. ''Ilex'' has the most species of any woody dioecious angiosperm genus. The species are evergreen o ...

'' (holly, an evergreen woody plant). It can inhibit

electron transport An electron transport chain (ETC) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples thi ...

cellular respiration Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor such as oxygen to produce large amounts of energy, to drive the bulk production of ATP. Cellular respiration may be des ...

, induce

vomiting Vomiting (also known as emesis and throwing up) is the involuntary, forceful expulsion of the contents of one's stomach through the mouth and sometimes the nose. Vomiting can be the result of ailments like food poisoning, gastroenteri ...

diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...

, and mild

narcosis Narcosis may refer to: In science * Carbon dioxide narcosis, carbon dioxide retention leading to a reduction in the hypoxic drive * Hydrogen narcosis, an effect of diving deep with hydrogen * Nitrogen narcosis, an effect of diving deep with nit ...

in animals. *

Emodin Emodin (6-methyl-1,3,8-trihydroxyanthraquinone) is a chemical compound, of the anthraquinone family, that can be isolated from rhubarb, buckthorn, and Japanese knotweed ('' Reynoutria japonica'' syn. ''Polygonum cuspidatum''). Emodin is particula ...

is a carbon-based

compound in plants like rhubarb. Emodin can be

cathartic In medicine, a cathartic is a substance that ''accelerates'' defecation. This is similar to a laxative, which is a substance that ''eases'' defecation, usually by softening feces. It is possible for a substance to be both a laxative and a catha ...

or act as a

laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, lubri ...

in humans, kills

dipteran Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced m ...

larvae, inhibits growth of bacteria and fungi, and deters consumption by birds and mice. * Starch is a polysaccharide that is slowly converted to fructose as the fruit ripens.

Frugivorous animals

Avian species

Birds are a main focus of frugivory research. An article by Bette A. Loiselle and John G. Blake, "Potential Consequences of Extinction of Frugivorous Birds for Shrubs of a Tropical Wet Forest", discusses the important role frugivorous birds have on ecosystems. The conclusions of their research indicate how the extinction of seed-dispersing species could negatively affect seed removal, seed viability, and plant establishment. The article highlights the importance that seed-dispersing birds have on the deposition of plant species. Examples of seed-dispersing birds are the hornbill, the

toucan Toucans (, ) are members of the Neotropical near passerine bird family Ramphastidae. The Ramphastidae are most closely related to the American barbets. They are brightly marked and have large, often colorful bills. The family includes five g ...

, the

aracari An aracari or araçari ( , , ) is any of the medium-sized toucans that, together with the saffron toucanet, make up the genus ''Pteroglossus''. They are brightly plumaged and have enormous, contrastingly patterned bills. These birds are reside ...

, the

cotinga The cotingas are a large family, Cotingidae, of suboscine passerine birds found in Central America and tropical South America. Cotingas are birds of forests or forest edges, that are primary frugivorous. They all have broad bills with hooked t ...

(ex.

Guianan cock-of-the-rock The Guianan cock-of-the-rock (''Rupicola rupicola'') is a species of cotinga, a passerine bird from South America. It is about in length and weighs about . It is found in tropical rainforests, near its preferred habitat of rocky outcrops. The ...

), and some species of

parrot Parrots, also known as psittacines (), are birds of the roughly 398 species in 92 genera comprising the order Psittaciformes (), found mostly in tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittacoide ...

s. Frugivores are common in the

temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

, but mostly found in the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

. Many frugivorous birds feed mainly on fruits until nesting season, when they incorporate protein-rich insects into their diet. Facultatively-baccivorous birds may also eat bitter berries, such as juniper, in months when alternative foods are scarce. In North America, red mulberry (''

Morus rubra ''Morus rubra'', commonly known as the red mulberry, is a species of mulberry native to eastern and central North America. It is found from Ontario, Minnesota, and Vermont south to southern Florida, and west as far as southeastern South Dakota, ...

'') fruits are widely sought after by birds in spring and early summer; as many as 31 species of birds were recorded visiting a fruiting tree in

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...

. Prior to 1980, most reports of avian frugivory were made in the tropics. From 1979–1981, a number of studies recognized the importance of fruits to fall temperate assemblages of

passerine A passerine () is any bird of the order Passeriformes (; from Latin 'sparrow' and '-shaped'), which includes more than half of all bird species. Sometimes known as perching birds, passerines are distinguished from other orders of birds by t ...

migrants. The earliest of these field studies were conducted in the fall of 1974 in

upstate New York Upstate New York is a geographic region consisting of the area of New York State that lies north and northwest of the New York City metropolitan area. Although the precise boundary is debated, Upstate New York excludes New York City and Long Is ...

by Robert Rybczynski & Donald K. Riker and separately by John W. Baird in

New Jersey New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...

, each documenting ingestion of fruits in stands of fruit-bearing shrubs by mixed species assemblages dominated by migrant

white-throated sparrow The white-throated sparrow (''Zonotrichia albicollis'') is a passerine bird of the New World sparrow family Passerellidae. Etymology The genus name ''Zonotrichia'' is from Ancient Greek (, ) and (, ). The specific ''albicollis'' is from Lati ...

Mammals

Mammals are considered frugivorous if the seed is dispersed and able to establish. One example of a mammalian frugivore is the

maned wolf The maned wolf (''Chrysocyon brachyurus'') is a large canine of South America. It is found in Argentina, Brazil, Bolivia, Peru, and Paraguay, and is almost extinct in Uruguay. Its markings resemble those of foxes, but it is neither a fox nor a w ...

, or ''Chrysocyon brachyurus'', which is found in South America. A study by José Carlos Motta-Junior and Karina Martins found that the maned wolf is probably an important seed disperser. The researchers found that 22.5–54.3% of the diet was fruit. 65% of the diet of

orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...

s consists of fruit. Orangutans primarily eat fruit, along with young leaves, bark, flowers, honey, insects, and vines. One of their preferred foods is the fruit of the durian tree, which tastes somewhat like sweet custard. Orangutans discard the skin, eat the flesh, and spit out the seeds. Other examples of mammalian frugivores include

fruit bat Megabats constitute the family Pteropodidae of the order Chiroptera (bats). They are also called fruit bats, Old World fruit bats, or—especially the genera '' Acerodon'' and ''Pteropus''—flying foxes. They are the only member of the ...

s and the

gray-bellied night monkey The gray-bellied night monkey (''Aotus lemurinus''), also called the grey-legged douroucouli

"Owl monkeys are frugivores and supplement their diet with flowers, insects, nectar, and leaves (Wright 1989; 1994). They prefer small, ripe fruit when available and in order to find these, they forage in large-crown trees (larger than ten meters 2.8 ft (Wright 1986). Seasonal availability of fruit varies across environments. Aotus species in tropical forests eat more fruit throughout the year because it is more readily available compared to the dry forests where fruit is limited in the dry season and owl monkeys are more dependent on leaves."

Conservation

Since

seed dispersal In Spermatophyte plants, seed dispersal is the movement, spread or transport of seeds away from the parent plant. Plants have limited mobility and rely upon a variety of dispersal vectors to transport their seeds, including both abiotic vectors ...

allows plant species to disperse to other areas, the loss of frugivores could change plant communities and lead to the local loss of particular plant species. Since frugivore seed dispersal is so important in the tropics, many researchers have studied the loss of frugivores and related it to changed plant population dynamics. Several studies have noted that even the loss of only large frugivores, such as monkeys, could have a negative effect, since they are responsible for certain types of long-distance seed dispersal that is not seen with other frugivore types, like birds. However, plant species whose seeds are dispersed by animals may be less vulnerable to fragmentation than other plant species. Frugivores can also benefit from the invasion of exotic fruit-producing species and can be vectors of exotic invasion by dispersing non-native seeds. Consequently, anthropogenic habitat loss and change may negatively affect some frugivore species but benefit others.