Seed-dispersing animals

Signal compounds to attract pollinating and seed dispersing animals... 

In some instances, additional functions are the attraction of pollinating or seed-dispersing animals, for example, by colored compounds such as betalains (within the Centrospermae), anthocyanins, carotenoids, and flavonoids or by fragrances such as terpenes, amines, and aldehydes 15,17). Physiological roles, such as UV protection [by fiavonoids or cou-marins 4,17)], nitrogen transport or storage 14,36,37), or photosynthesis (carotenoids), may be an additional function. 

Apocarotenoids also act as chemoattractants, repellants, and growth effectors in plants and cyanobacteria. They attract pollinators to plants through the use of color similar to full-length carotenoids. Their aromas are thought to be attractants for animals and insects to facilitate in seed dispersal and pollination. Small volatile apocarotenoids lure pollinators and levels of apocarotenoids... 

Secondary compounds produced by plants may have other significant survival roles, such as signals to attract insects, birds, or other animals to enhance pollination or seed dispersal. In addition to any potential functions, secondary compounds may concomitantly serve a physiologic function, such as protection against ultraviolet (UV) light or frost, or provide a function in nitrogen transport and storage. In several instances, compounds can serve multiple functions in the same plant. Anthocyanins or monoterpenes can be... 

The flavonoids are a remarkable group of plant metabolites. No other class of secondary product has been credited with so many — or such diverse — key functions in plant growth and development. Many of these tasks are critical for survival, such as attraction of animal vectors for pollination and seed dispersal, stimulation of Rhizobium bacteria for nitrogen fixation. 

The widest diversity in the manner of seed dispersal is exhibited by the dry fruits. These include the windborne types such as dandelion parachutes or sycamore keys . Mechanical scattering is exhibited by many of the legumes, whose seed pods, when fully ripened and dried out, can split with explosive force to scatter their contents in readiness for a follow-on crop. Another type is made up of those fruits, such as cleavers or dock-buns , that possess small hooks whereby the fruit is caught up in the fur of animals for transportation. 

Carotenoids involved in photosynthesis are bound to and help stabilize chlorophyll-protein complexes, of which various types occur in the lamellar membranes of chloroplasts (Fig. 1-10). Carotenoids also are found in organelles known as chromoplasts, which are about the size of chloroplasts and are often derived from them. For instance, lycopene (red) is in tomato fruit chromoplasts, and a- and pi-carotenes (orange) occur in carrot root chromoplasts. A great diversity of carotenoids occurs in the chromoplasts of flower petals, which is important for attracting pollinators, and fruits, which aids in seed dispersal by attracting other animals. 

Awareness of the dose necessary is, as always, crucial. In Canada an OP insecticide called phosphamidon was used to control insect pests on conifer trees. Initially the use of this pesticide killed many birds as well as the insect pest, but the Canadians found that by reducing the amount of the chemical used they could control the insects without affecting the bird population. Problems have occurred in particular when OPs have been used to treat seeds and, while this reduces dispersion, animals that eat the seeds can then be poisoned. This has caused the deaths of large numbers of birds in some areas. 

The dog units were labeled furaneol units because this compound is found in large quantity in many fruits (26). Besides being intensely sweet, this compound also has a fragrant odor and is a character impact compound for many fruits. It is believed that this dog furaneol taste system is specific for fruit and is linked with the seed dispersing function of the dog. The presence of this taste system and its absence is readily detectable in the natural eating behavior of canines and felids. In a natural environment canines will supplement their small animal diet with fruit of the season, unlike felids. Nucleotide responsive units are relatively rare in taste systems. The only other vertebrate nucleotide taste system that has been described is in the puffer fish (27). This fish facial nerve taste system, like that in the cat, also responded to a wide variety of nucleotides and to inorganic phosphate compounds. In invertebrates, nucleotide taste systems have been described for blood sucking animals where they are common (28). 

This high elevation plant diversity harbors extended animal communities which have not been sufficiently well studied. However, in as much as cross pollination and non-wind seed dispersal are fundamental mechanisms for plant species survival, this fauna is of crucial importance to vascular plant life. Although animal life is beyond the scope of the present chapter, the interested reader might find some specific reports instruetive (e.g. Pefaur and Duellman, 1980 Pefaur and Diaz de Pascual, 1985 Vuilleumier, 1986 Hoffstetter, 1986 Cei, 1986 Reig, 1986 Holloway, 1986 Villwock, 1986 Durant et al., 1994 Diaz et al., 1997). As far as arthropods and their influence in secondary plant metabolism, their species diversity has been observed to decline with elevation in some places (e.g. Fleishman et al., 1998). Some exceptions exist as the case of mite s abundance and species diversity in the Appalachians illustrates (Lamoncha and Crossley, 1998). However, more important than species richness to herbivory pressure is the number of individuals forming a herbivore population, a subject that requires further attention in high elevations before a clear picture on their influence on secondary plant metabolism may be assessed properly. 

Anthocyanins are among the most important groups of plant pigments. They are present in almost all higher plants and are the dominant pigments in many fruits and flowers, giving red, violet, or blue color. They play a definite role in attracting animals in pollination and seed dispersal. They may also have a role in the mechanism of plant resistance to insect attack. 

Succulent edible fruits seeds dispersed by animals Fruit. 

Several secondary monosaccharides have a sweet taste. If present in higher concentration they attract animals involved for instance in pollination or seed dispersal (E 5.5.1 and E 5.5.2) as well as human beings (F 1). 

Volatiles emitted from fruits determine their overall aroma properties and flavor which are perceived through olfactory detection of multiple distinct sensory inputs processed to generate the overall sensation [12]. Thus, fruit volatiles could play a role in the attraction of animal seed dispersers. For example, fruit bats can detect and locate fruits, as well as assess their ripeness, based on odor alone [13, 14]. Olfactory cues emanating from the food source are especially important in food location for nocturnal foragers which have limited access to visual cues, as was suggested for night monkeys and lemurs [15-17]. 

Anthocyanins help to attract animals which lead to seed dispersal and pollination (Strack and Wray, 1994). There is evidence that anthocyanins may play a role in protecting plants against ultraviolet (UV)-induced damage (Bohm, 1998). They may also be beneficial to human health because of their possible role as dietary antioxidants and anti-inflammatory agents (Tsuda et al., 1994, 1998 Wang et al., 1997, 1999). 

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