Herbivory is a form of predation in which an organism, known as a herbivore, consumes principally autotrophs[1] such as plants, algae and photosynthesizing bacteria. A deer is a Ruminant Mammal belonging to the family Cervidae. A heterotrophs, or chemoorganotrophy ( Greek heterone = (another and trophe = nutrition is an Organism that requires An autotroph (from the Greek autos = self and trophe = nutrition is an Organism that produces complex Organic compounds from simple Plants are living Organisms belonging to the kingdom Plantae. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have By that definition, many fungi, some bacteria, many animals, some protists and a small number of parasitic plants can be considered herbivores. A fungus (ˈfʌŋgəs is a eukaryotic Organism that is a member of the kingdom Fungi (ˈfʌndʒaɪ The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Protists (ˈproʊtɨst are a diverse group of eukaryotic Microorganisms Historically protists were treated as the kingdom Protista but this A parasitic plant is one that derives some or all of its sustenance from another plant However, herbivory is generally restricted to animals eating plants. Fungi, bacteria and protists that feed on living plants are usually termed plant pathogens. Microbes that feed on dead plants are saprotrophs. Flowering plants that obtain nutrition from other living plants are usually termed parasitic plants. A parasitic plant is one that derives some or all of its sustenance from another plant More generally, organisms that feed on autotrophs in general are known as primary consumers.
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Herbivores
A herbivore is an animal that is adapted to eat primarily plant matter (rather than meat). Leaf miner is a term used to describe the Larvae of many different species of Insect which live in and eat the Leaf tissue of plants Plants are living Organisms belonging to the kingdom Plantae. In modern English usage meat most often refers to Animal tissue used as food mostly Skeletal muscle and associated Fat, but it may also refer Although such animals are sometimes referred to as being vegetarian, this term is more properly reserved for humans who choose not to eat meat as opposed to animals that are unable to make such choices. Vegetarianism is the practice of a diet that excludes Meat (including game and slaughter by-products Fish (including Shellfish and other sea Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus The diets of some herbivorous animals vary with the seasons, especially in the temperate zones, where different plant foods are most available at different times of year.
There is a misperception that if an animal is herbivorous, it represents less danger to humans than a carnivore (or, sometimes, no danger at all). A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting This is not logically sound; few animals, even carnivores, will seek humans as a food source, but any animal will attack a human if necessary to defend itself. For example, in national parks such as the United States' Yellowstone Park, bison represent significantly more danger to humans than wolves, which are likely to avoid people. A national park is a reserve of land usually declared and owned by a national Government, protected from most Human development and pollution The United States of America —commonly referred to as the Of Africa's Big Five game (a term coined by hunters in Africa to refer to the five most dangerous animals to hunt: Rhinoceros, Leopard, Cape Buffalo, Elephant and Lion), three are herbivores. The phrase Big Five game was coined by Big-game hunters and refers to the five most difficult animals in Africa to hunt on foot Rhinoceros (raɪˈnɒsərəs often colloquially abbreviated rhino, is a name used to group five extant species of Odd-toed ungulates in the family The leopard (lɛpɚd Panthera pardus) is an Old World Mammal of the Felidae family and the smallest of the four roaring The African Buffalo or Cape Buffalo ( Syncerus caffer) is a large African bovid. Elephants ( family: Elephantidae) are large land Mammals of the order Proboscidea. The lion ( Panthera leo) is a member of the family Felidae and one of four Big cats in the Genus Panthera.
Herbivores form an important link in the food chain as they transform the sun's energy stored in the plants to food that can be consumable by carnivores and omnivores up the food chain. A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting Omnivores (from Latin omne all everything vorare to devour are species that eat both Plants and Animals as their primary As such, they are termed the primary consumers in the food chain.
Feeding strategies
Herbivores differ in the extent, specificity and nature of their feeding.
They can be grouped according to which part of the plant they eat: frugivores which eat mainly fruit; folivores, which specialize in eating leaves; nectarivores, which feed on nectar; among herbivorous insects and other arthropods, the level of feeding specialization can be far more fine-tuned, including seed-eaters ("granivores"), pollen-eaters ("palynivores"), plant fluid-feeders ("mucivores"), and those specialized to feed on wood ("xylophages") or roots ("rhizophages"). A frugivore is an Animal that feeds primarily or in some cases exclusively on Fruit. The term fruit has different meanings dependent on context and the term is not synonymous in Food preparation and Biology. In Zoology, a folivore is a Herbivore that specializes in eating Leaves. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. In Zoology, a nectarivore is an animal which eats the sugar-rich Nectar produced by Flowering plants Nectar is a Sugar -rich liquid produced by plants It is produced either by the Flowers in which it attracts pollinating animals or by extrafloral Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Arthropods are Animals belonging to the Phylum Arthropoda (from Greek ἄρθρον arthron, " Joint " In Zoology, a granivore is an Herbivorous animal which selectively eats the nutrient-rich Seeds produced by plants including those of Gymnosperms In Zoology, a palynivore is an Herbivorous animal which selectively eats the nutrient-rich Pollen produced by flowering plants including Gymnosperms Not to be confused with Xylophagia Xylophagy is a term used in Ecology to describe the habits of an Herbivorous animal In other animals, the degree of specialization is not so advanced, however, and many fruit- and leaf-eating animals also eat other parts of plants, notably roots and seeds. ROOT is an object-oriented program and library developed by CERN. A seed (in some plants referred to as a kernel) is a small embryonic Plant enclosed in a covering called the seed coat usually with some stored
The techniques used to get at the foodstuff are wide and varied, and include the "pierce and suck" technique, surface fluid feeding, hole feeding, margin feeding and skeletonisation. [2]
Evolution of herbivory
Our understanding of herbivory in geological time comes from three sources: fossilised plants, which may preserve evidence of defence (such as spines), or herbivory-related damage; the observation of plant debris in fossilised animal faeces; and the construction of herbivore mouthparts. A Coprolite is Fossilized animal dung Coprolites are classified as trace fossils as opposed to body fossils as they give evidence for the animal's behaviour (in [2]
Long thought to be a Mesozoic phenomenon, evidence for herbivory is found almost as soon as fossils which could show it. The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. Within under 20 million years of the first fossils of sporangia and stems towards the close of the Silurian, around , there is evidence that they were being consumed. [3] Animals fed on the spores of early Devonian plants, and the Rhynie chert also provides evidence that organisms fed on plants using a "pierce and suck" technique. The Rhynie chert is an Early Devonian Lagerstätte found near the village of Rhynie, Aberdeenshire, Scotland, containing exceptionally [2]
During the ensuing 75 million years, plants evolved a range of more complex organs - from roots to seeds. There is no evidence for these being fed upon until the middle-late Mississippian, . There was a gap of 50 to 100 million years between each organ evolving, and it being fed upon; this may be due to the low levels of O2 during this period, which may have suppressed evolution. [3] Further than their arthropod status, the identity of these early herbivores is uncertain. [3] Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period. [2]
Arthropods have evolved herbivory in four phases, changing their approach to herbivory in response to changing plant communities. [4]
Plant defences
Plant defence against herbivory include a range of adaptations evolved by plants to improve their survival and reproduction by reducing the impact of animals that eat them. Plant defense against herbivory or host-plant resistance (HPR includes a range of Adaptations evolved An adaptation is a characteristic of an Organism that has been favored by Natural selection and Plants have evolved an enormous array of mechanical and chemical defences against herbivores.
These defences include mechanical protections on the surface of the plant, production of complex polymers that reduce plant digestibility to animals, and the production of toxins that kill or repel herbivores. A polymer is a large Molecule ( Macromolecule) composed of repeating Structural units typically connected by Covalent Chemical bonds Digestion is the breaking down of chemicals in the body into a form that can be absorbed A toxin ( Greek:, toxikon, lit (poison for use on arrows is a Poisonous substance produced by living cells or organisms that is active at very low Defenses can either be constitutive, always present in the plant, or induced, produced or translocated by the plant following damage or stress. The term host plant resistance is also used by plant breeders to refer to these mechanisms.
Plants have also evolved features that enhance the probability of attracting natural enemies to herbivores. Specifically, they emit semiochemicals, odors that attract natural enemies, and provide food and housing to maintain the natural enemies’ presence. A semiochemical (semeon means a signal in Greek is a generic term used for a chemical substance or mixture that carries a message
A given plant species often has many types of defensive mechanisms, mechanical or chemical, constitutive or induced, which additively serve to protect the plant, and allow it to escape from herbivores.
In some cases, herbivory is actually encouraged by plants to assist in reproduction. A notable example is the production of nectar to attract bees, which are necessary for pollination.
Herbivore adaptations to defences
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. 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 In a broad sense biological co-evolution is "the change of a biological object triggered by the change of a related object" Herbivores 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. [5] 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. eVolution is the third Album by eLDee, it was due to be released in 2008 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. Natural selection is the process by which favorable Heritable traits become more common in successive Generations of a Population of Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as In cases where this relationship demonstrates “specificity” (the evolution of each trait is due to the other), and “reciprocity” (both traits must evolve), the species are thought to have coevolved. [6] 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. Speciation is the Evolutionary process by which new biological Species arise [7][8]
See also
References
- ^ Campbell, N. Grazing generally describes a type of Predation in which an Herbivore feeds on Plants (such as Grasses, or more broadly on a multicellular Pollination in angiosperms and Gymnosperms is the process that transfers pollen grains, which contain the male Gametes (sperm to where the female Biological dispersal refers to those processes by which a Species maintains ecosystem Seed predation includes any process inflicted on a Plant ’s seeds by an animal that results in the inviability of the Seed. A. (1996) Biology (4th edition) Benjamin Cummings, New York ISBN 0-8053-1957-3
- ^ a b c d Labandeira, C. C. (1998). "Early History Of Arthropod And Vascular Plant Associations 1". Annual Reviews in Earth and Planetary Sciences 26 (1): 329-377. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ a b c Labandeira, C. (2007). "The origin of herbivory on land: Initial patterns of plant tissue consumption by arthropods". Insect Science 14 (4): 259-275. doi:. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
- ^ Labandeira, C. C. (2006). "The four phases of plant-arthropod associations in deep time" (Free full text). Geologica Acta 4 (4): 409-438.
- ^ Karban, R. , and A. A. Agrawal. 2002. Herbivore offense. Annual Review of Ecology and Systematics 33:641 – 664.
- ^ Futuyma, D. J. and M. Slatkin. 1983. Introduction. Pages 1−13 in D. J. Futuyma and M. Slatkin, editors. Coevolution. Sinauer Associates Inc. , Sunderland, Massachusetts, USA.
- ^ Ehrlich, P. R. and P. H. Raven. 1964. Butterflies and plants: a study of coevolution. Evolution 18:586-608.
- ^ Thompson, J. 1999. What we know and do not know about coevolution: insect herbivores and plants as a test case. Pages 7–30 in H. Olff, V. K. Brown, R. H. Drent, and British Ecological Society Symposium 1997 (Corporate Author), editors. Herbivores: between plants and predators. Blackwell Science, London, UK.
Further reading
- Danell, K. , R. Bergström, P. Duncan, J. Pastor (Editors)(2006) Large herbivore ecology, ecosystem dynamics and conservation Cambridge, UK : Cambridge University Press. 506 p. ISBN 0521830052
- Crawley, M. J. (1983) Herbivory : the dynamics of animal-plant interactions Oxford : Blackwell Scientific. 437 p. ISBN 0632008083
- Olff, H. , V. K. Brown, R. H. Drent (editors) (1999) Herbivores : between plants and predators Oxford ; Malden, Ma. : Blackwell Science. 639 p. ISBN 0632051558
External links
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