Pollination By Other Mammals
Non-flying mammals (to distinguish them from bats) have been found to feed on the nectar of several species of plant. Though some of these mammals are pollinators, others do not carry or transfer enough pollen to be considered pollinators (Johnson 2001). This group of non-flying pollinators is mainly composed of marsupials, primates, and rodents (Johnson 2001). Well-documented studies of non-flying mammal pollination now involve at least 59 species of mammal distributed among 19 families and six orders (Carthewa 1997). As of 1997, there were 85 species of plants from 43 genera and 19 families which were visited by these mammals (Carthewa 1997). In many cases, a plant species is visited by a range of mammals. Two examples of multiple mammal pollinotion are the genus Quararibea which is visited by 12 species and Combretum which is visited by 8 (Carthewa 1997).
Plant species that feed non-flying mammals will often exhibit similar characteristics to aid in pollination. The flowers are often large and sturdy, or are grouped together as multi-flowered inflorescences. Many non-flying mammals are nocturnal and have an acute sense of smell, so the plants tend not to have bright showy colors, but instead excrete a pungent odor. Plants will often flower profusely and produce a large amount of sugar-rich nectar. These plants also tend to produce large amounts of pollen because mammals are larger than some other pollinators, and lack the precision smaller pollinators can achieve (Carthewa 1997). Animals with more precision, such as bees or other insects with a proboscis, can pollinate small flowers with less pollen necessary. This means that a plant will require more pollen for a larger mammal pollinator.
One example of a symbiotic relationship between a plant and its animal pollinators is the African Lily, Massonia depressa, and some rodent species of the Succulent Karoo region of South Africa. At least four rodent species, including two gerbil species, were found to be visiting M. depressa during the night (Johnson 2001). Traits of the M. depressa flowers support non-flying mammal pollination. It has dull-colored and very sturdy flowers at ground level, has a strong yeasty odor, and secretes copious amounts of sucrose-dominant nectar during the night (Johnson 2001). The nectar of M. depressa was also found to be 400 times as viscous, or resistant to flow, as an equivalent sugar solution. This jelly-like consistency of the nectar may discourage insect consumption while also facilitating lapping by rodents. It is assumed that M. depressa coevolved with its pollinators (Johnson 2001).
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