Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores (seed predators) feed on the seeds of plants as a main or exclusive food source, in many cases leaving the seeds damaged and not viable. Granivores are found across many families of vertebrates (especially mammals and birds) as well as invertebrates (mainly insects); thus, seed predation occurs in virtually all terrestrial ecosystems. Seed predation is commonly divided into two distinctive temporal categories, pre-dispersal and post-dispersal predation, which affect the fitness of the parental plant and the dispersed offspring (the seed), respectively. Mitigating pre- and post-dispersal predation may involve different strategies. To counter seed predation, plants have evolved both physical defenses (e.g. shape and toughness of the seed coat) and chemical defenses (secondary compounds such as tannins and alkaloids). However, as plants have evolved seed defenses, seed predators have adapted to plant defenses (e.g., ability to detoxify chemical compounds). Thus, many interesting examples of coevolution arise from this dynamic relationship.
Plant seeds are important sources of nutrition for animals across most ecosystems. Seeds contain food storage organs (e.g., endosperm) that provide nutrients to the developing plant embryo (cotyledon). This makes seeds an attractive food source for animals because they are a highly concentrated and localized nutrient source in relation to other plant parts.
Seeds of many plants have evolved a variety of defenses to deter predation. Seeds are often contained inside protective structures or fruit pulp that encapsulate seeds until they are ripe. Other physical defenses include spines, hairs, fibrous seed coats and hard endosperm. Seeds, especially in arid areas, may have a mucilaginous seed coat that can glue soil to seed hiding it from granivores.
Some seeds have evolved strong anti-herbivore chemical compounds. In contrast to physical defenses, chemical seed defenses deter consumption using chemicals that are toxic or distasteful to granivores or that inhibit the digestibility of the seed. These chemicals include toxic non-protein amino acids, cyanogenic glycosides, protease and amylase inhibitors, and phytohemaglutinins. Plants may face trade-offs between allocation toward defenses and the size and number of seeds produced.
Plants may reduce the severity of seed predation by making seeds spatially or temporally scarce to granivores. Seed dispersal away from the parent plant is hypothesized to reduce the severity of seed predation. Seed masting is an example of how plant populations are able to temporally regulate the severity of seed predation. Masting refers to a concerted abundance of seed production followed by a period of paucity. This strategy has the potential to regulate the size of the population of seed predators.
Adaptations to defend seeds against predation can impact seeds' ability to germinate and disperse. Thus anti-predator adaptations often occur in a suite of adaptations for a particular seed life history. For example, chili plants selectively deter mammal seed predators and fungi using capsaicin, which does not deter bird seed dispersers because bird taste receptors do not bind with capsiacin. Chili seeds in turn have higher survival if they pass through a bird's stomach than if they fall to the ground.
Seed predation can occur both before and after seed dispersal.
Pre-dispersal seed predation takes place when seeds are removed from the parent plant before dispersal, and it has been most often reported in invertebrates, birds, and in granivorous rodents that clip fruits directly from trees and herbaceous plants. Post-dispersal seed predation arises once seeds have been released from the parent plant. Birds, rodents, and ants are known to be among the most pervasive postdispersal seed predators. Furthermore, postdispersal seed predation can take place at two contrasting stages: predation on the "seed rain" and predation on the "seed bank". Whereas predation on the seed rain occurs when animals prey on released seeds usually flush with the ground surface, predation on the seed bank takes place after seeds have been incorporated deeply into the soil. Nevertheless, there are important vertebrate pre-dispersal predators, especially birds and small mammals.
Post-dispersal seed predation is extremely common in virtually all ecosystems. Given the heterogeneity in both resource type (seeds from different species), quality (seeds of different ages and/or different status of integrity or decomposition) and location (seeds are scattered and hidden in the environment), most post-dispersal predators have generalist habits. These predators belong to a diverse array of animals, such as ants, beetles, crabs, fish, rodents and birds. The assemblage of post-dispersal seed predators varies considerably among ecosystems. A dispersed seed is the first independent life stage of a plant, thus post-dispersal seed predation is the first potential mortality event and one of the first biotic interactions in a plant's life cycle.
Both pre- and post-dispersal seed predation are common. Pre-dispersal predators differ from post-dispersal predators in most often being specialists, adapted to clustered resources (on the plant). They use specific cues like plant chemistry (volatile compounds), color, and size to locate seeds, and their short life cycles often match the production of seeds by the host plant. Insect groups containing many pre-dispersal seed predators are Coleoptera, Hemiptera, Hymenoptera and Lepidoptera.
The complex relationship between seed predation and plant demography is an important topic of plant-animal interactive studies. Plant population structure and size over time is closely associated with the effectiveness at which seed predators locate, consume, and disperse seeds. In many cases this relationship depends on the type of seed predator (specialist vs. generalist) or the particular habitat in which the interaction is taking place. The role of seed predation on plant demography may be either detrimental or in particular cases actually beneficial to plant populations.
The Janzen-Connell model concerns how seed density and survival respond to distance from the parent tree and differential rates of seed predation. Seed density is hypothesized to decrease as distance from the parent tree increases. Where seeds are most abundant under the parent tree, seed predation is predicted to be at its highest. As distance from the parent tree increases, seed abundance and thus seed predation are predicted to decrease as seed survival increases.
The degree to which seed predation influences plant populations may vary by whether a plant species is safe site limited or seed limited. If a population is safe site limited it is likely that seed predation will have little impact to the success of the population. In safe site limited populations increased seed abundance does not translate into increased seedling recruitment. However, if a population is seed limited, seed predation has a better chance of negatively affecting the plant population by decreasing seedling recruitment. Maron and Simms found both safe site limited and seed limited populations depending on the habitat in which the seed predation was taking place. In dune habitats seed predators (deer mice) were limiting seedling recruitment in the population, thus negatively affecting the population. However, in grassland habitat the seed predator had little effect on the plant population because it was safe site limited.
In many cases seed predators support plant populations by dispersing seeds away from the parent plant, in effect supporting gene flow between populations. Other seed predators collect seeds and then store or cache them for later consumption. In the case that the seed predator is unable to locate the buried or hidden seed there is a chance that it will later germinate and grow, supporting the species dispersal. Generalist (vertebrate) seed predators may also aid the plant in other indirect ways, for instance by inducing top-down control on host-specific seed predators (termed "intra-guild predation"), and as such negating Janzen-Connell type effects and so benefiting the plant in competition with other plant species.
The beetle subfamily Aulacoscelidinae (sometimes misspelled "Aulacoscelinae") is a small, uncommonly-encountered group presently classified within the family Orsodacnidae, historically placed as a subfamily of Chrysomelidae, or sometimes classified as a separate family Aulacoscelidae. There are only 19 species, mostly Neotropical in distribution, and their larval habits are unknown.Cape spiny mouse
The Cape spiny mouse (Acomys subspinosus) is a murid rodent found in the Western Cape Province of South Africa. They have a dorsal covering of spiny hairs with dark grey-brown coloration, and a white underbelly. The Cape Spiny Mouse has large eyes and ears and a scaly, nearly bald tail that is brittle and can break off readily either as a whole or in part if it is caught. Their total length is 17 cm, with an 8 cm tail, and they typically weigh 22g.Coleophora triplicis
Coleophora triplicis is a moth of the family Coleophoridae. It is found in Canada, including New Brunswick and Nova Scotia. This species has also been recorded on Prince Edward Island in a salt marsh ecosystem. In Prince Edward Island, it was observed as a predator of the predispersed seeds of the Gulf of Saint Lawrence aster (Symphyotrichum laurentianum Fernald).The larvae feed on the seeds of Solidago sempervirens. They create a trivalved, tubular silken case.Defaunation
Defaunation is the global, local or functional extinction of animal populations or species from ecological communities. The growth of the human population, combined with advances in harvesting technologies, has led to more intense and efficient exploitation of the environment. This has resulted in the depletion of large vertebrates from ecological communities, creating what has been termed "empty forest". Defaunation differs from extinction; it includes both the disappearance of species and declines in abundance. Defaunation effects were first implied at the Symposium of Plant-Animal Interactions at the University of Campinas, Brazil in 1988 in the context of neotropical forests. Since then, the term has gained broader usage in conservation biology as a global phenomenon.It is estimated that more than 50 percent of all wildlife has been lost in the last 40 years. in 2020 it is estimated that 68% of the world's wildlife will be lost. In South America, there is believed to be a 70 percent loss.In November 2017, over 15,000 scientists around the world issued a second warning to humanity, which, among other things, urged for the development and implementation of policies to halt "defaunation, the poaching crisis, and the exploitation and trade of threatened species."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 multiple dispersal steps on the plant fitness and population dynamics depends on the type of dispersers involved. In many cases, secondary seed dispersal by (typically granivorous) invertebrates or rodents moves seeds over a relatively short distance and a large proportion of the seeds may be lost to seed predation within this step. Longer dispersal distances and potentially larger ecological consequences follow from sequential endochory by two different animals, i.e. diploendozoochory: a primary disperser that initially consumes the seed, and a secondary, carnivorous animal that kills and eats the primary consumer along with the seeds in the prey’s digestive tract, and then transports the seed further in its own digestive tract.
More than one dispersal vector (abiotic or biotic) is thought to be involved in the majority of seed dispersal events (on average 2.15 dispersal vectors in Dutch ecosystems).
Seeds may be transported in turn by various animal or abiotic mechanisms such as wind or water.Dipterocarpus intricatus
Dipterocarpus intricatus (Khmer: tra:ch, tra:ch sa, tra:ch snaèng, tra:ch sra:, Thai: yang-krat) is a species of tree in the family Dipterocarpaceae found in Thailand, Cambodia, Laos and Vietnam. The tree, itself deciduous, is found in dense deciduous forests and clear forests. It is often met in pure stands in deciduous, periodically flooded lowland forests, but can also be found in dense forest at up to 1300m altitude. In Thailand it sometimes occurs growing gregariously with D. obtusifolious, D. tuberculatus, Shorea robusta and S. siamensis, sometimes in pure stands forming the climatic dry deciduous dipterocarp forest. This forest type covered a large area of eastern, north-eastern and northern Thailand, from peneplain at 150-300m elevations to slope and ridges up to 1300m above sea level. It does also occur in Lowland dipterocarp forest (0-350m) in Thailand. In Vietnam, it is described as common in dry forests. The tree prefers poor, sandy and lateritic soils derived from granitic and sandstone formations. Seedlings develop hardy rootstock and thick rough bark on the stout stem, affording fire-protection in the ground-fire prone early hot dry season. Coppicing occurs freely up to a moderate size. In Thailand leaves are shed from November, defoliation is complete by February, with leaf starting at this time, or sometimes a little before. Flowering occurs from February to April, fruiting from April to May, though in certain areas or some years with a late rainy season these periods start up to 3 months earlier. The species grows from 15 to 30m tall.The fruit has 2 prominent, elongated, netted wings, 6–8 cm long x 1.5–2 cm wide, on top of an ovoid or ellipsoid fruit-body, 1.5–2 cm long x 1-1.5 cm wide, with undulate ribs, 2-3mm wide.In Cambodia the resin is mainly used in torch-preparation, while the red-brown wood is "appreciated" for cart and house construction. Sold as "fancy wings" in the potpourri tradeThe genus Nanophyes is associated with seed predation of D. intricatus.Ecology of Banksia
The ecology of Banksia refers to all the relationships and interactions among the plant genus Banksia and its environment. Banksia has a number of adaptations that have so far enabled the genus to survive despite dry, nutrient-poor soil, low rates of seed set, high rates of seed predation and low rates of seedling survival. These adaptations include proteoid roots and lignotubers; specialised floral structures that attract nectariferous animals and ensure effective pollen transfer; and the release of seed in response to bushfire.
The arrival of Europeans in Australia has brought new ecological challenges. European colonisation of Australia has directly affected Banksia through deforestation, exploitation of flowers and changes to the fire regime. In addition, the accidental introduction and spread of plant pathogens such as Phytophthora cinnamomi (dieback) pose a serious threat to the genus's habitat and biodiversity. Various conservation measures have been put in place to mitigate these threats, but a number of taxa remain endangered.Empty forest
Empty forest is a term coined by Kent H. Redford's article "The Empty Forest" (1992), which was published in BioScience. An "empty forest" refers to an ecosystem that is void of large mammals. Empty forests are characterized by an otherwise excellent habitat, and often have large, fully grown trees, although they lack large mammals as a result of human impact. Empty forests show that human impact can destroy an ecosystem from within as well as from without.Many of the large mammals that are disappearing, such as deer and tapirs, are important for seed dispersion. Many tree species that are very localized in their dispersion rely on mammals rather than the wind to disperse their seeds. Furthermore, when seed predation is down, trees with large seeds begin to completely dominate those with small seeds, changing the balance of plant life in an area.Predatory large mammals are important for increasing overall diversity by making sure that smaller predators and herbivores do not become overabundant and dominate. An absence of large predators seems to result in uneven densities of prey species. Even though certain animals may not have become completely extinct, they may have lowered in numbers to the point that they have suffered an ecological extinction. The animals that have most likely suffered an ecological extinction in neotropical forests are the ones who are the most important predators, large seed dispersers, and seed predators.The defaunation of large mammals can be done by direct or indirect means. Any type of human activity not aimed at the animals in question that results in the defaunation of those animals is indirect. The most common means of indirect defaunation is habitat destruction. However, other examples of indirect means of defaunation of large mammals would be the over-collection of fruits and nuts or over-hunting of prey that large mammals need for food. Another example of an indirect means of the defaunation of large mammals is through the by-products of modern human activities such as mercury and smoke, or even noise pollution.There are two categories of direct defaunation. They include subsistence hunting and commercial hunting. The most common species of animals hunted are typically the largest species in their area. The large mammals in an area are often represented by only a few species, but make up a major part of the overall biomass. In areas with only moderate hunting, the biomass of mammalian game species decreases by 80.7%. In areas with heavy hunting, the biomass of mammalian game species can decrease by 93.7%.Epicephala
Epicephala (leafflower moths) is a genus of moths in the family Gracillariidae.
Epicephala is of note in the fields of pollination biology and coevolution because many species in this genus are pollinators of plants in the genera Glochidion, Phyllanthus, and Breynia (Phyllanthaceae). These pollinating Epicephala actively pollinate the flowers of their host plants—thereby ensuring that the plants may produce viable seeds—but also lay eggs in the flowers' ovaries, where their larvae consume a subset of the developing seeds as nourishment. This relationship is similar to other specialized pollinating seed-predation mutualisms such as those between figs and fig wasps and yuccas and yucca moths.
Other species of Epicephala consume the seeds of species of Phyllanthus or Flueggea (Phyllanthaceae) as larvae, but do not pollinate their host plants as adults. At least some of these species have evolved from pollinating ancestors.Grevillea kennedyana
Grevillea kennedyana is a sprawling shrub of the genus Grevillea. It is only found in a small part of Australia, with a natural range less than 100 km. It is considered a vulnerable under federal and state legislation. G. kennedyana is also known as the flame spider-flower.Harvester ant
Harvester ant, also known as harvesting ant, is a common name for any of the species or genera of ants that collect seeds (called seed predation), or mushrooms as in the case of Euprenolepis procera, which are stored in the nest in communal chambers called granaries. They are also referred to as Agricultural ants. Seed harvesting by some desert ants is an adaptation to the lack of typical ant resources such as prey or honeydew from hemipterans. Harvester ants increase seed dispersal and protection, and provide nutrients that increase seedling survival of the desert plants. In addition, ants provide soil aeration through the creation of galleries and chambers, mix deep and upper layers of soil, and incorporate organic refuse into the soil.Liberian mongoose
The Liberian mongoose (Liberiictis kuhni) is a small carnivoran belonging to the mongoose family (Herpestidae). It is the only member of the genus Liberiictis. Phylogenetic analysis shows it is closely related to other small, social mongooses and that the banded mongoose is its closest relative.It was discovered in Liberia in 1958. Little was known about the animal, except what local natives related. They typically forage in packs consisting of 3-8 individuals, but larger groups have been observed. Their diet consists of earthworms and various insects. The exact distribution is unknown, but may extend from Sierra Leone to Côte d'Ivoire. Confirmed sightings are restricted to forests in Liberia and the Tai National Park in Côte d'Ivoire. Human activity such as mining, agriculture, hunting and logging has displaced the Liberian mongoose from its previous range. A live specimen was exhibited at the Toronto Zoo, but civil war in Liberia has prevented further study. Due to its limited range and the fact that it is heavily hunted, the Liberian mongoose is considered endangered.The Liberian mongoose has a primarily dark brown body, with a darker stripe on the neck and shoulders. This stripe is bordered by smaller stripes that are white. Compared with other mongoose species, the Liberian mongoose has rather long claws and an elongated snout with small teeth relative to the size of the skull. It has a bushy tapering tail, that is less than half of the length of the head and body. This is likely an adaptation of their specialized diet of earthworms. One of the few specimens ever seen alive was found in a burrow close to a termite nest. The animal's physical characteristics, and its preferred locality to insects, has led experts to suggest that the Liberian mongoose is primarily insectivorous. The few observers that have witnessed this species in the wild have reported that the animal lives primarily in the trunks of trees. Indeed, some of the better-known mongoose species live in tree during the rainy season and occupy burrows only during hotter weather. The collection of juveniles at the end of July and a lactating female at the beginning of August suggests that breeding coincides with the rainy season, when there is an increase in food availability.This species is extremely rare, and has been listed by the IUCN as endangered. Human destruction of their habitat and human hunting are the primary threats to Liberian mongooses. Owing to their rarity, they were not described until 1958, with the first complete specimens discovered as recently as 1974. An attempt to study them in 1988 yielded only one animal, which had already been killed by a hunter. The specimen that lived at the Toronto Zoo has since died. This rarity also limited what is understood about the Liberian mongoose's interaction with other aspects of the ecosystem. Recent work has shown that they may act as an ecosystem engineer by maintaining the heterogeneity of the forest floor. Through field observations and radio-tracking, a group of mongooses was followed for a period of three months, with a record of their foraging traces being kept. As they forage, they disturb the leaf litter and soil, with an estimate that they may be able to overturn the entire forest floor in a period of 8 months. This altering of the litter environment indirectly affects seed predation and germination. The Liberian mongoose is also host to a species of Mallophaga (chewing louse) known as Felicola liberiae. Political unrest in the areas in which they live has made further studies difficult in recent years.Mast (botany)
Mast is the "fruit of forest trees like acorns and other nuts". The term "mast" comes from the old English word "mæst", meaning the nuts of forest trees that have accumulated on the ground, especially those used historically for fattening domestic pigs, and as food resources for wildlife. In the aseasonal tropics of South-East Asia, entire forests including hundreds of species are known to mast at irregular periods of 2–12 years.More generally, mast is considered the edible vegetative or reproductive part produced by woody species of plants, i.e. trees and shrubs, that wildlife species and some domestic animals consume. Mast is found in two forms. Mast is generated in large quantities during mast seeding events (or masting, mast events). Mast seeding is a population-level phenomenon that is hypothesized to be driven by economies of scale, weather, and resources. These pulses of resources drive ecosystem-level functions and dynamics.Myrmecochory
Myrmecochory ( (sometimes myrmechory); from Ancient Greek: μύρμηξ, romanized: mýrmēks and χορεία khoreíā "circular dance") is seed dispersal by ants, an ecologically significant ant-plant interaction with worldwide distribution. Most myrmecochorous plants produce seeds with elaiosomes, a term encompassing various external appendages or "food bodies" rich in lipids, amino acid, or other nutrients that are attractive to ants. The seed with its attached elaiosome is collectively known as a diaspore. Seed dispersal by ants is typically accomplished when foraging workers carry diaspores back to the ant colony after which the elaiosome is removed or fed directly to ant larvae. Once the elaiosome is consumed the seed is usually discarded in underground middens or ejected from the nest. Although diaspores are seldom distributed far from the parent plant, myrmecochores also benefit from this predominantly mutualistic interaction through dispersal to favourable locations for germination as well as escape from seed predation.Parthenocarpy
In botany and horticulture, parthenocarpy is the natural or artificially induced production of fruit without fertilisation of ovules, which makes the fruit seedless. Stenospermocarpy may also produce apparently seedless fruit, but the seeds are actually aborted while they are still small. Parthenocarpy (or stenospermocarpy) occasionally occurs as a mutation in nature; if it affects every flower the plant can no longer sexually reproduce but might be able to propagate by apomixis or by vegetative means.
However, parthenocarpy of some fruits on a plant may be of value. Up to 20% of the fruits of wild parsnip are parthenocarpic. The seedless wild parsnip fruit are preferred by certain herbivores and so serve as a "decoy defense" against seed predation. Utah juniper has a similar defense against bird feeding. The ability to produce seedless fruit when pollination is unsuccessful may be an advantage to a plant because it provides food for the plant's seed dispersers. Without a fruit crop, the seed dispersing animals may starve or migrate.
In some plants, pollination or another stimulation is required for parthenocarpy, termed stimulative parthenocarpy. Plants that do not require pollination or other stimulation to produce parthenocarpic fruit have vegetative parthenocarpy. Seedless cucumbers are an example of vegetative parthenocarpy, seedless watermelon is an example of stenospermocarpy as they are immature seeds (aborted ones).
Plants that moved from one area of the world to another may not always be accompanied by their pollinating partner, and the lack of pollinators has spurred human cultivation of parthenocarpic varieties. Some parthenocarpic varieties have been developed as genetically modified organisms.Phyllary
In botanical terminology, a phyllary, also known an involucral bract or tegule, is a single bract of the involucre of a composite flower. The involucre is the grouping of bracts together. Phyllaries are reduced leaf-like structures that form one or more whorls immediately below a flower head.Predation
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as a seed predator is both a predator and a herbivore.
Predators may actively search for prey or sit and wait for it. When prey is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation, sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it.
Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate and invertebrate, have sharp claws or jaws to grip, kill, and cut up their prey. Other adaptations include stealth and aggressive mimicry that improve hunting efficiency.
Predation has a powerful selective effect on prey, and the prey develop antipredator adaptations such as warning coloration, alarm calls and other signals, camouflage, mimicry of well-defended species, and defensive spines and chemicals. Sometimes predator and prey find themselves in an evolutionary arms race, a cycle of adaptations and counter-adaptations. Predation has been a major driver of evolution since at least the Cambrian period.Pyrogenic flowering
Pyrogenic flowering is the fire-stimulated flowering of plants in heathland and other fire-prone habitats. It is associated with species which have transient seed banks, as opposed to canopy or persistent soil seed banks. These species are mostly monocots, but it is also observed in several species of woody dicots.One of the most well known species to display this life cycle are those in the Waratah (Telopea) genus. With Telopea speciosissima being the floral emblem of the Australian state of New South Wales.Wrinkle-faced bat
The wrinkle-faced bat (Centurio senex) is a species of bat in the family Phyllostomidae and the only identified member of the genus Centurio. These bats are found in various countries in and around Central America. They eat fruit but are not classified within the fruit bats. They are classified as a leaf-nosed bat but do not have a leaf nose. They have an unusually shaped skull which is thought to allow them to eat a wider range of foods than other bats.