Temperate grasslands are biomes at mid-latitude geographies. Grasslands have fertile soils, and grasses are the predominant species of vegetation, with areas often fragmented by the conversion of natural spaces to agriculture. Temperate grasslands generally have low precipitation (10-20 inches per year) and are impacted by both drought and fire conditions. The fauna of temperate grasslands is unique and the relationships between species include several instances of symbiosis.
General Symbiotic Relationships
Symbiotic relationships are close relationships between two or more different species, where one species' behavior influences the other species.There are three main types of symbiotic relationships. The first is mutualism, where both species experience positive benefits from the interaction. The second is commensalism, where one species benefits and the other species experiences no effect. The third is parasitism, where one species benefits and the other species experiences negative effects or harm.
Mutualism in Temperate Grasslands
Grasslands are cellulose-rich environments, since the dominant vegetation is grass. Cellulose is difficult for many species to break down. In grasslands, bacteria unique to ruminants that lives in the stomachs of large herbivores helps to break down cellulose. In this way, the bacteria thrives in the stomach of the herbivores and the herbivores are able to metabolize cellulose.
Commensalism in Temperate Grasslands
Cattle frequent grassland biomes. They graze on the short and long grasses present across the landscape. As they graze, they disturb insects in the surrounding areas. Cattle egrets have adapted to feed on the disturbed insects flushed from the grasses by the cattle. The cattle receive no benefit, but the cattle egrets benefit from the food source. For another example, nurseplants are found in many biomes. Large nurseplants provide protection for young seedlings growing under the leaves of the nurseplant. They protect young seedlings from grazing by herbivores, frost stress in the winter months and heat stress in the summer months, though the large nurseplants do not benefit.
Parasitism in Temperate Grasslands
Rattle is a genus of herb that is considered semiparasitic. Rattle lives on the roots of grasses and gains sustenance from feeding on the flow of nutrients and water through the roots. The presence of rattle reduces nutrient flow to the grasses and also reduces the competitive dominance of grasses, allowing other species such as herbs to grow in the grasslands. A parasitic animal, the brown-headed cowbird is native to both grassland and cropland environments. They are brood parasites, meaning that the brown-headed cowbirds lay eggs in the nests of other grassland birds and force the other species to hatch the eggs and raise the young. The advantage to the cowbird is the low investment in raising young while still passing genes to new generations, while the cost is passed on to the host species.
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- Interaction Assessment Worksheets; Symbiotic Relationships; Alan and Hui Meng; 2011.
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- Don't Want Something Bland, Come to the Temperate Grassland; Kevan Keelan; 2007.
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- University of Texas Press; Cowbird Parasitism in Grassland and Cropland in the Northern Great Plains; Rolf Koford, et al.; 2000.
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