Ecology and evolution of plant–pollinator interactions | Annals of Botany | Oxford Academic
The truly spectacular diversity of plants that we know today wouldn't be possible without these complex interactions between plants, pollinators. We assessed how the associations between plant and pollinator the relationships between several measures of the composition of plant and. All is not well in the realm of pollinators. The age-old relationships between plants and pollinators is threatened, especially in urbanized and.
Current research, however, is revealing that herbivory has some potential benefits to plants. One example is canopy grazing by insects, which allows more light to penetrate into the lower layers of the forest. Gypsy moth grazing on canopy trees in some areas of Virginia's Blue Ridge Mountains, for instance, has resulted in more light penetration and therefore a more diverse and productive ground layer. Herbivores and Their Food Plants Bison, sheep, and other grazers - Succulent forbs, grasses, grass-like plants Deer and other ungulate browsers - Leaves and twigs of woody plants such as willows, arborvitaes, yews Beaver - Tree bark, young shoots, leaves Rodents - Succulent forbs, grasses, grass-like plants Rabbits - Succulent forbs, grasses, bark Voles - Roots, bark Caterpillars - Leaves; in some cases, of specific species Monarch butterfly - Milkweeds Gypsy moth - Oaks and other hardwoods Aphids - Plant juices; in some cases, of specific species Many birds - Seeds and fruits Locusts - All plants; seeds, leaves, and stems Plants and Their Pollinators Pollination is the transfer of the pollen from one flower to the stigma, or female reproductive organ, of another, which results in fertilization and, ultimately, the formation of seeds.
The earliest plants were pollinated by wind, and for some modern plants this is still the most expedient method. Many trees, all grasses, and plants with inconspicuous flowers are designed for wind pollination. Bright, showy flowers evolved for another purpose—to attract a pollinator. Many plants depend on animals for pollination. Insects, birds, even bats are important for perpetuating plants.
The flowers of these plants evolved in concert with their pollinators, and their form reflects the form and habits of their pollinators. Bee-pollinated plants are often irregular in shape, with a lip that acts as a landing pad to facilitate the bee's entry into the flower.
Butterfly-pollinated flowers are often broad and flat, like helicopter pads.
- Plant/Animal Relationships
The flowers of many plants are brightly colored to attract their insect pollinators, and many offer nectar as an enticement. Hummingbirds, with their long beaks, pollinate tubular flowers. Bats require open flowers with room for their wings, such as those of the saguaro cactus.
In the tropics, birds and bats take the place of insects as pollinators. Hummingbirds and honeycreepers, for example, have distinctive beaks that have evolved to exploit flowers.
Often, a beak may be so specialized that it is only effective on a small group of flowers. The pollinators, in turn, have evolved to take advantage of the flowers. A successful pollinator typically has good color vision, a good memory for finding flowers, and a proboscis, or tongue, for attaining nectar.
Animal pollination has obvious advantages for plants. Many pollinators cover great distances, which insures genetic diversity through outcrossing, or the transfer of pollen to unrelated individuals. The pollinator benefits as well by gaining access to a source of food. The relationship of pollinator plant is an example of mutualism. Imperiled Pollinators All is not well in the realm of pollinators.
The age-old relationships between plants and pollinators is threatened, especially in urbanized and agricultural regions. Habitat destruction and fragmentation, pesticide abuse, and disease all have taken their toll on pollinators. As more land is cleared for human habitation, bees, butterflies, bats, and birds are left homeless. Our gardens offer little to sustain them.
They need a constant source of nectar and pollen throughout the entire season. Because pollinators are species upon which the lives of so many other species depend they are regarded as "keystone species". Pollinators are thus essential to the stability of the global ecosystem itself. In fact without pollinators life on planet Earth would be very different. Not only are our native plants dependent upon pollinators for their continued existence but so are our crops.
Eighty percent of the world's crop species including food beverage medicine dye and fiber crops rely on animal pollinators. The critical importance of pollination has been recognized since humans first gave up nomadic lifestyles.
That great symbol of human-pollinator partnering beekeeping began long ago at least by B. The first beekeepers were most likely Egyptians who floated hives up and down the Nile to provide pollination services to floodplain farmers while simultaneously producing a honey crop. Domestic honey bees Apis mellifera introduced to North America from Europe in the mids now play a role in pollinating 80 percent of the crop varieties grown in the United States and a significant percentage in Canada.
However the story is complex. Because European honey bees have been introduced worldwide they now compete with native bees and other native insects around the world and it is now virtually impossible to find an area free of managed or feral honey bees.
Honey bees out-compete native insect pollinators by overwhelming them with their sheer numbers and superior ability to detect and direct one another to pollen and nectar sources. Further complicating the story at the same time that the almost the whole world has become dependent on domestic honey bees their populations are declining in many parts of the world including Canada due to exotic introduced bee parasites e.
The aggressive Africanized bees out-compete the European honey bees but do not pollinate all the same plants and crops. The direct competition between European and Africanized honey bees with native species is reducing the numbers of native pollinators and it is adding to the pollination crisis that the world faces today.
And most recently we have colony collapse disorder which does not seem to be impacting Canadian beekeepers at least not yet. Like many other animals on Earth pollinators today face growing threats of extinction.
Plant-Pollinator Relationships | Plant Ecology
The authors of the orchid study also suggest that the unpredictability of pollinators could have a been a significant hurdle to early flowering plants Aguiar et al. These questions may seem simple to those familiar with ecological concepts, but the ability to answer them explicitly is a central problem to the field of ecology.
Theoretical research attempting to model specific mechanisms of plant-pollinator dynamics has found that most competitive pollination interactions should lead to a loss of biodiversity Kunin and Iwasa Yet this is not the only result we observe. More recent models were able to show that such positive feedback loops can be circumvented by utilizing a classic form of competition avoidance: When specialization was high enough in pollinator competition models, relative ecosystem stability was possible however there are other, non-pollination-related stabilizing mechanisms currently known, but not modeled in the cited study.
Such specialists sacrifice the ability to respond to changing conditions for a unique place in a relatively stable ecosystem, and would not be very successful if disturbances or changing climate disrupted their pollinators and habitats. Indeed, we are currently witnessing disturbance-driven changes in ecosystems that are affecting diverse and specialized organisms most drastically Franzen and Oeckinger Many of these changes are caused directly or indirectly by humans, including habitat fragmentation and rapid climate changeand represent serious threats to pollination dynamics and thus biodiversity Phillips et al.People, Plants and Pollinators - Nat Geo Live
These topics will be discussed in upcoming posts on pollination ecology.