Folivore

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Elephants are an example of a mammalian folivore. Elephant mother.jpg
Elephants are an example of a mammalian folivore.

In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds. [1] For this reason, folivorous animals tend to have long digestive tracts and slow metabolisms. Many enlist the help of symbiotic bacteria to release the nutrients in their diet. Additionally, as has been observed in folivorous primates, they exhibit a strong preference for immature leaves which tend to be easier to masticate, are higher in energy and protein, and lower in fibre and poisons than more mature fibrous leaves. [1]

Contents

Evolution

Herbivory has evolved several times among different groups of animals. The first vertebrates were small fish that consumed protists and invertebrates. After these fish, the next group of vertebrates to evolve were piscivores, then insectivores, carnivores and finally herbivores. [2] Since a complex set of adaptations was necessary for feeding on highly fibrous plant materials (structural modifications to the teeth, jaws, and digestive tract) and only a small proportion of extant tetrapods are obligate herbivores, it could be that early tetrapods made the transition to fully fledged herbivory by way of omnivory. [2]

Folivory and flight

A hoatzin Opisthocomus hoazin.jpg
A hoatzin

It has been observed that folivory is extremely rare among flying vertebrates. [3] Morton (1978) attributed this to the fact that leaves are heavy, slow to digest, and contain little energy relative to other foods. [3] The hoatzin is an example of a flighted, folivorous bird. There are, however, many species of folivorous flying insects.

Some bats are partially folivorous; their method of deriving nourishment from leaves, according to Lowry (1989), is to chew up the leaves, swallowing the sap and spitting out the remainder. [4]

Arboreal folivores

A brown-throated three-toed sloth Bradypus.jpg
A brown-throated three-toed sloth

Arboreal mammalian folivores, such as sloths, koalas, and some species of monkeys and lemurs, tend to be large and climb cautiously. [5] Similarities in body shape and head- and tooth-structure between early hominoids and various families of arboreal folivores have been advanced as evidence that early hominoids were also folivorous. [5]

Primates

Standard ecological theory predicts relatively large group sizes for folivorous primates, as large groups offer better collective defense against predators and they face little competition for food among each other. It has been observed that these animals nevertheless frequently live in small groups. Explanations offered for this apparent paradox include social factors such as increased incidence of infanticide in large groups. [6]

A howler monkey Alouatta-caraya ppia-m01b.jpg
A howler monkey

Folivorous primates are relatively rare in the New World, the primary exception being howler monkeys. One explanation that has been offered is that fruiting and leafing occur simultaneously among New World plants. However a 2001 study found no evidence for simultaneous fruiting and leafing at most sites, apparently disproving this hypothesis. [7]

Examples

Examples of folivorous animals include:

An okapi Okapi2.jpg
An okapi

See also

Related Research Articles

<span class="mw-page-title-main">Primate</span> Order of mammals

Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians. Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dexterous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs 30 g (1 oz), to the eastern gorilla, weighing over 200 kg (440 lb). There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and six in the 2020s.

<span class="mw-page-title-main">Herbivore</span> Organism that eats mostly or exclusively plant material

A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, and other tough plant material.

<span class="mw-page-title-main">Hoatzin</span> Species of bird in South America

The hoatzin or hoactzin is a species of tropical bird found in swamps, riparian forests, and mangroves of the Amazon and the Orinoco basins in South America. It is the only extant species in the genus Opisthocomus which is the only extant genus in the Opisthocomidae family under the order of Opisthocomiformes. The taxonomic position of this family has been greatly debated by specialists, and is still far from clear.

<span class="mw-page-title-main">Howler monkey</span> Genus of mammals

Howler monkeys are the most widespread primate genus in the Neotropics and are among the largest of the platyrrhines along with the muriquis (Brachyteles), the spider monkeys (Ateles) and woolly monkeys (Lagotrix). The monkeys are native to South and Central American forests. They are famous for their loud howls, which can be heard up to three miles away through dense rain forest. Fifteen species are recognized. Previously classified in the family Cebidae, they are now placed in the family Atelidae. They are primarily folivores but also significant frugivores, acting as seed dispersal agents through their digestive system and their locomotion. Threats include human predation, habitat destruction, illegal wildlife trade, and capture for pets or zoo animals.

<span class="mw-page-title-main">Colobinae</span> Subfamily of Old World monkeys

The Colobinae or leaf-eating monkeys are a subfamily of the Old World monkey family that includes 61 species in 11 genera, including the black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split the colobine monkeys into two tribes, while others split them into three groups. Both classifications put the three African genera Colobus, Piliocolobus, and Procolobus in one group; these genera are distinct in that they have stub thumbs. The various Asian genera are placed into another one or two groups. Analysis of mtDNA confirms the Asian species form two distinct groups, one of langurs and the other of the "odd-nosed" species, but are inconsistent as to the relationships of the gray langurs; some studies suggest that the gray langurs are not closely related to either of these groups, while others place them firmly within the langur group.

<span class="mw-page-title-main">Atelinae</span> Subfamily of New World monkeys

The Atelinae are a subfamily of New World monkeys in the family Atelidae, and includes the various spider and woolly monkeys. The primary distinguishing feature of the atelines is their long prehensile tails, which can support their entire body weight.

A generalist species is able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources. A specialist species can thrive only in a narrow range of environmental conditions or has a limited diet. Most organisms do not all fit neatly into either group, however. Some species are highly specialized, others less so, and some can tolerate many different environments. In other words, there is a continuum from highly specialized to broadly generalist species.

<span class="mw-page-title-main">Colombian red howler</span> Species of monkey

The Colombian red howler or Venezuelan red howler is a South American species of howler monkey, a type of New World monkey, found in the western Amazon Basin in Venezuela, Colombia, Ecuador, Peru and Brazil. The population in the Santa Cruz Department in Bolivia was split off as a separate species, the Bolivian red howler, in 1986, and more recently, splitting off the population in northeastern South America and Trinidad as the Guyanan red howler has occurred. All howler monkeys belong to the family Atelidae and the infraorder Platyrrhini.

<span class="mw-page-title-main">Brown howler</span> Species of New World monkey

The brown howler, also known as brown howler monkey, is a species of howler monkey, a type of New World monkey that lives in forests in southeastern Brazil and far northeastern Argentina (Misiones). It lives in groups of two to 11 individuals. Despite the name "brown howler", it is notably variable in colour, with some individuals appearing largely reddish-orange or black.

<span class="mw-page-title-main">Mantled howler</span> Species of New World monkey

The mantled howler is a species of howler monkey, a type of New World monkey, from Central and South America. It is one of the monkey species most often seen and heard in the wild in Central America. It takes its "mantled" name from the long guard hairs on its sides.

<i>Suminia</i> Extinct genus of therapsids

Suminia is an extinct genus of basal anomodont that lived during the Tatarian age of the late Permian, spanning approximately from 268-252 Ma. Suminia is recognized the youngest non-dicynodont anomodont. Its fossil localities are primarily derived from the Kotel’nich locality of the Kirov Oblast in Russia. However, there have been some isolated specimen found in a few different localities, all from eastern European regions of Russia.

Herbivores are dependent on plants for food, and have coevolved mechanisms to obtain this food despite the evolution of a diverse arsenal of plant defenses against herbivory. Herbivore adaptations to plant defense have been likened to "offensive traits" and consist of those traits that allow for increased feeding and use of a host. Plants, on the other hand, protect their resources for use in growth and reproduction, by limiting the ability of herbivores to eat them. Relationships between herbivores and their host plants often results in reciprocal evolutionary change. When a herbivore eats a plant it selects for plants that can mount a defensive response, whether the response is incorporated biochemically or physically, or induced as a counterattack. In cases where this relationship demonstrates "specificity", and "reciprocity", the species are thought to have coevolved. The escape and radiation mechanisms for coevolution, presents the idea that adaptations in herbivores and their host plants, has been the driving force behind speciation. The coevolution that occurs between plants and herbivores that ultimately results in the speciation of both can be further explained by the Red Queen hypothesis. This hypothesis states that competitive success and failure evolve back and forth through organizational learning. The act of an organism facing competition with another organism ultimately leads to an increase in the organism's performance due to selection. This increase in competitive success then forces the competing organism to increase its performance through selection as well, thus creating an "arms race" between the two species. Herbivores evolve due to plant defenses because plants must increase their competitive performance first due to herbivore competitive success.

<span class="mw-page-title-main">Mexican howler</span> Subspecies of New World monkey

The Mexican howler is a subspecies of the mantled howler, A. palliata. This subspecies is found predominantly in forests between south eastern Mexico and north eastern Peru. Typical of its species, the Mexican howler monkey has a prehensile tail, a deep jaw, and a large pharynx which it uses to make characteristically deep and resonating howls. Mantled howler monkeys are known for forming unusually large cohorts averaging 14 members and sometimes extending to 40 members.

<span class="mw-page-title-main">Tufted gray langur</span> Species of Old World monkey

The tufted gray langur, also known as Madras gray langur, and Coromandel sacred langur, is an Old World monkey, one of the species of langurs. This, like other gray langurs, is mainly a leaf-eating monkey. It is found in southeast India and Sri Lanka. It is one of three Semnopithecus species named after characters from The Iliad, S. hector and S. ajax being the others. In Sinhala it is known as හැලි වදුරා.

<span class="mw-page-title-main">Subfossil lemur</span> Lemurs from Madagascar that are represented by recent (subfossil) remains

Subfossil lemurs are lemurs from Madagascar that are represented by recent (subfossil) remains dating from nearly 26,000 years ago to approximately 560 years ago. They include both extant and extinct species, although the term more frequently refers to the extinct giant lemurs. The diversity of subfossil lemur communities was greater than that of present-day lemur communities, ranging to as high as 20 or more species per location, compared with 10 to 12 species today. Extinct species are estimated to have ranged in size from slightly over 10 kg (22 lb) to roughly 160 kg (350 lb). Even the subfossil remains of living species are larger and more robust than the skeletal remains of modern specimens. The subfossil sites found around most of the island demonstrate that most giant lemurs had wide distributions and that ranges of living species have contracted significantly since the arrival of humans.

Ficus yoponensis is a species of fig tree found in Central and South America. It can grow to heights of 40–50 metres (130–160 ft) tall, having a trunk diameter of 1 metre (3.3 ft). The trunk is buttressed, light grey in colour and reasonably smooth. Its petioles are 1–2.5 centimetres (0.39–0.98 in) long, the stipules are straight and 3–5 centimetres (1.2–2.0 in) long. The leaves and stems are hairless. The leaves are 6–11 centimetres (2.4–4.3 in) long and 2.5–4 centimetres (0.98–1.57 in) wide, but larger in juveniles, being up to 28 centimetres (11 in) long and 5 centimetres (2.0 in) wide. The time at which they flower varies between individuals, but each tree tends to flower at a similar time each year. As in all figs, the flowers are enclosed inside the fig and can only be accessed by fig wasps, which enter to pollinate the flowers and lay their own eggs. The resulting fruit grows to 1.8 centimetres (0.71 in) in diameter and turns from green to purple with maturity. On average in Panama, F. yoponensis produce a new flush of leaves every 20 weeks and flower every 25 weeks. The species is similar in appearance to Ficus insipida but has smaller leaves, stipules and fruits and only occurs in primary forest whereas F. insipida is also found in secondary forest.

Hindgut fermentation is a digestive process seen in monogastric herbivores. Cellulose is digested with the aid of symbiotic bacteria. The microbial fermentation occurs in the digestive organs that follow the small intestine: the large intestine and cecum. Examples of hindgut fermenters include proboscideans and large odd-toed ungulates such as horses and rhinos, as well as small animals such as rodents, rabbits and koalas. In contrast, foregut fermentation is the form of cellulose digestion seen in ruminants such as cattle which have a four-chambered stomach, as well as in sloths, macropodids, some monkeys, and one bird, the hoatzin.

Lepidosaur herbivory describes herbivorous lepidosaurs. Living non-avian reptiles form a paraphyletic group that consists of over 9,000 species of crocodiles, turtles, and lepidosaurs. The most diverse group, Lepidosauria, is first known from the Middle Triassic fossils, but likely originated in the Permian. Living lepidosaurs, which include snakes, lizards, and rhynchocephalians, occupy a wide range of environments and niches. The lepidosaurs have many similar anatomical morphology like transverse cloaca, distal tongue, superficial teeth attachment, fused pelvic bones etc. Though widely viewed as obligate carnivores, a small number of lepidosaurs are known to consume plant material. For example, there are roughly 3,300 species of living lizards and approximately 3% of them eat at least some plants. Though the exact definition of herbivory varies significantly between scientists, most define herbivorous lepidosaurs as those that consume plants for approximately 70-90% of its diet.

Sivaladapis is a genus of adapiform primate that lived in Asia during the middle Miocene.

References

  1. 1 2 Jones, S., Martin, R., & Pilbeam, D. (1994) The Cambridge Encyclopedia of Human Evolution. Cambridge: Cambridge University Press
  2. 1 2 Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica". Geology. 38 (12): 1079–1082. doi:10.1130/G31182.1.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. 1 2 Do the Power Requirements of Flapping Flight Constrain Folivory in Flying Animals? R. Dudley, G. J. Vermeij Functional Ecology, Vol. 6, No. 1 (1992), pp. 101-104
  4. Folivory in Bats: An Adaptation Derived from Frugivory by T. H. Kunz and K. A. Ingalls; Functional Ecology, Vol. 8, No. 5 (Oct., 1994), pp. 665-668
  5. 1 2 Cautious climbing and folivory: a model of hominoid differentation E. E. Sarmiento1 in Human Evolution Volume 10, Number 4, August, 1995
  6. Competition and group size in Thomas's langurs (Presbytis thomasi): the folivore paradox revisited R. Steenbeek and Carel P. van Schaik: Behavioral Ecology and Sociobiology Volume 49, Numbers 2-3 / January, 2001; Print ISSN   0340-5443; Online ISSN   1432-0762
  7. Heymann, Eckhard W. (2001). "Can phenology explain the scarcity of folivory in New World primates?". American Journal of Primatology. 55 (3): 171–175. doi:10.1002/ajp.1050. ISSN   1098-2345. PMID   11746280. S2CID   8344876.
  8. "The Diet of a Generalized Folivore: Iguana iguana in Panama". www.anapsid.org. Retrieved 2024-02-05.