Granivores

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 may involve different strategies and requirements and have different implications at the individual and population level. Nevertheless, regardless of timing, seed predation has great implications for plant population dynamics. To counterbalance effects of predation, plants have evolved defenses such as seed morphology (size, shape, toughness) and chemical defenses (secondary compounds such as tannins and alkaloids) to defend against their seed predators. However, as plants have adapted defenses to seed predation (e.g., chemical compounds), so have seed predators adapted to plant defenses (e.g., ability to detoxify chemical compounds). Thus, many interesting examples of coevolution arise from this dynamic relationship.

Most humans are predominantly granivores, even if they eat a wide variety of other foods.

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 from seed predators. Plants may allocate resources toward physical or chemical defenses. 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.

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