Biodiversity and Pollination
Before we can go to the pollination party, we have to get ready by exploring why this topic should matter to us and our students. Don’t worry-- I’ll still give you time to get your party outfit ready!
Biodiversity is Earth’s living variety in all of its forms and interactions. Biodiversity spans across many levels of organisms, including genes, species, communities, and ecosystems, where interactions occur with the local physical environment. The interactions of all of these levels and environments in our local communities feed into global biodiversity. We seek to have classrooms that are “biodiverse” in composition because these are the strongest learning communities, giving our students windows and mirrors for deeper learning and understanding.3
We can see biodiversity out of our classroom window by looking at all the plants, animals, and other living organisms. The air we breathe, the water we drink, and the food we eat are all dependent on the robustness of our biodiversity. Studies of ecosystems show innumerable interactions from the tiniest of microbes to the largest of mammals that foster the sustainability of our living Earth.
One such system of interactions is pollination. Many plants use seeds as a means of reproducing and spreading new plants. Flowers use pollination to make their seeds. The process of pollination is a mutually beneficial interaction between flowering plants and pollinators. Pollination occurs between flowers that are of the same species. Insect pollinators seek nectar (i.e. carbohydrates) or pollen (i.e. protein) from flowers. While the pollinators eat, they contact pollen through specific behaviors or body structures which allow them to carry and share pollen between the flowers they visit.4
For example, bees perform a specific behavior to get pollen out of some flowers. Plants like tomatoes release their pollen through two smalls holes in each anther. To help the plants release the pollen, bees bite the anthers and buzz to shake out the pollen. The buzz is a middle C tone, which can shake free thousands of pollen granules from a flower in just one second. Bees also have structural adaptations that help them retrieve and carry pollen. Bees have tiny hairs that make them look fuzzy. The hairs are primarily on the bee’s abdomen and legs, which helps them collect pollen on their bodies. The bees transfer pollen between the flowers they visit when pollen falls off or sticks to their hairs. Bees also use these hairs to carry nectar and pollen back to their nests to feed the hive.5 These adaptations enhance bees’ pollination efforts.
But pollinators are not the only ones with adaptations. Plants and pollinators have been evolving together for millions of years, resulting in many physical adaptations. These adaptations help attract pollinators to the plants (see Figure 1).6
Figure 1. Shown are flowers with adaptations that attract pollinators.
Pansies, Azaleas, and Forget-Me-Nots are all examples of flowers that use their bright colors to attract pollinators. The colors of flowers often lead pollinators to the areas of nectar with patterns and pathways. Think of how common it is for the centers of flowers to be bright yellow—this is intentional attraction! Bees are particularly attracted to blue, violet, and purple flowers. It is no coincidence that flowers in the violet-blue shades make the highest amount of nectar. These flowers capitalize on bees’ unique and complex sight systems. Though humans can see more colors than bees, bees are able to see a broader range of vision, including ultraviolet light. Some of the patterns on flowers appear in ultraviolet light, making them invisible to humans’ naked eyes. For example, pansies have a nectar bullseye pattern but it is only visible in ultraviolet light. These patterns help pollinators easily find a plant’s source of pollen and nectar.7
Some plants use their smells (both good and very bad) to attract pollinators. Flowers release scents to let pollinators know that they are ready for pollination. The Moonflower releases a sweet, dreamy smell into the air to attract nighttime pollinators like moths and bats. Pawpaw flowers smell like rotting flesh, which attracts carrion flies and scavenger beetles to pollinate them. Peruvian Apple Cactus releases a sweet scent as well, but for one night only! Local bats or moths will make their way to this plant on one evening a year.
In addition to their patterns, colors, and smells, some flowers have physical structures that support pollinators landing on them. The center of flowers like a Daisy are an easy landing pad for pollinators. Salvia flowers have a special mechanism for distributing pollen to pollinators in which a stamen acts a lever. When the pollinator pushes into the flower’s lower lever arm, the stamen drops a pollen packet. This is then pressed onto the pollinator by the upper lever arm, and is usually dropped on the top of the pollinator or its head. Salvia attracts a range of pollinators including bees, butterflies, and hummingbirds. The trumpet flower is shared like a long bell, which is the perfect shape for the long skinny beak of a hummingbird to pollinate it.
Other ways that flowers have adapted in ways that support pollinators include the location where they grow, or the timing during which they bloom. Magnolia flowers bloom near the ground or on lower portions of the plant to attract beetles from the ground. Some pollinators like the monarch butterflies will travel thousands of miles in migration, following the location of milkweed growth north from Mexico. Rosemary is an important early source of nectar and pollen for many pollinators, blooming as early as midwinter in some places because it can withstand cold temperatures. It also continues to bloom throughout spring and summer, making it a reliable food source for pollinators across seasons.
Adaptations like these help plants attract the maximum number of pollinators to their flowers. The more times a plant is visited by a pollinator, the more chances it has to make seeds. But the plants are not alone in needing pollinators. Without pollinators, most flowers would be unable to fertilize their seeds, meaning that there would be no fruit or nuts to consume. This would significantly impact the food sources of both humans and animals alike. Pollinators are responsible for nearly 1/3 of the food on our human plate, covering over 140 different crop plants.8 Pollinators have an estimated market value of up to $577 billion USD annually, which represents about 10% of the global crop market.9 Produce like apples, almonds, oranges, avocados, peaches, pears, plums, cherries, alfalfa, blueberries, vanilla, cranberries, tomatoes, kiwi, figs, coffee, strawberries, blackberries, raspberries, lemons, limes, eggplants, kumquats, nectarines, grapes, and cacao all depend on pollinators.10 In regards to nutrients for health, pollinator-dependent plants contain more than 90% of the world’s vitamin C, 100% of lycopene, and almost all of antioxidants b-cryptoxanthin and b-tocopherol, most of the lipid (74%), vitamin A (>70%), and related cartenoids (98%), calcium (58%), fluoride (62%), and folic acid (55%). This data implies that declines in pollinator populations could increase preventable human diseases that are linked to nutrient-rich diets, especially in places already vulnerable to nutrient deficiencies.11
Despite the vital role of pollinators in biodiversity and their impact on global food supply, medicine, and more, human beings have not acted as a collective to prioritize pollinator health. Human development has caused damage to pollinator populations through habitat loss, monoculture farming, and pesticide use. Many urban conservation efforts focus on connecting people to nature, such as through outreach, recreation facilities, and education initiatives, but these have not resulted in the change needed to keep pollinators healthy.12 In my research of this topic, I observed that many of these programs also focus on one group of species, such as bees or butterflies. While I recognize the benefits of focusing on one core species, I wonder if are participants walking away with an understanding of the interdependencies that one species fosters? Ecosystems are critically interconnected, and can require changes across the entire system to create effective, healthy change. I work a second job as an outdoor educator for my local parks and recreation department, and I regularly observe that participants are excited to learn about nature, but there is often little follow through in connecting this learning to actionable efforts or changed behaviors in the local community. In other words, it isn’t enough. We need to be doing something more intentional, more impactful, and in my opinion, more actionable. And I think it requires community participation. Just like my classroom shows more learning growth when all students are participating, our collective goals can be accomplished if local citizens are actually participating in bettering community health.
Many of the connections between the animal, plant, and human world happen in invisible ways, which can make them challenging to teach. I have taught exceptional educations learners explicitly for the past 7 years and this challenge is only amplified for these students. Studies have shown that our students are not able to articulate scientific knowledge that is critical to understanding the ways that living organisms are interacting in systems like pollination.13 Our students make transparent and non-transparent choices every day that can impact their health. It is critical that we are teaching science in a way that makes it visible and relevant to students. If students are not able to understand processes like pollination, they are not able to make the most impactful changes in their communities to support pollinators.
In a study conducted on college students majoring in biology, students in the study frequently intermingled the separate processes of fertilization, pollination, and seed dispersal. Students were often unable to articulate how plants are pollinated, and were not able to show specific content knowledge about the topic.14 I reference this study in particular because the authors recommend implementing a Pollination Systems Knowledge Assessment (PKSA) to assess levels of pollination knowledge and to identify what parts of the pollination systems learner’s struggle to understand.15 The PKSA was designed to be adapted across grade levels so that educators can choose assessment components that relate to their content at an age-appropriate level. This is a first step towards helping teachers understand more concretely what their students do and do not know about pollination, which could lead to improved science instruction across education with coordinated efforts at data collection. Regardless of the broader impacts, we utilize pre- and post-assessments frequently in the classroom! Implementing more data-based instruction in science at my school is a high need based off students’ overall low science standards of learning assessment scores over the past five years of instruction.
I think it is important to also note here that even the experts aren’t exactly clear on what students really need to know—for example, the Entomological Society of America, the largest academic society of entomologists (aka people who study insects), has no formal criteria or standards for what students should know about pollination or pollination conservation. There is no systematic method for us to determine the success of implemented interventions in terms of pollination systems knowledge gains, nor to identify learners’ misconceptions regarding pollinator knowledge that may hinder pollinator conservation behaviors.16 And this just focuses on the bees! Even less is known about what students really know about other pollinators, like birds, bats, or moths.
A quick aside about answering their questions: please check the science! It is important that while I educate students on these topics to build their care in nature, I am also informing them of factual scientific knowledge. For example, I chose a book as a mentor text for this unit whose author included a set of references and research that she based her book on. Her sources include field guides, the US Forest Service, nature centers, and more. Kindergarteners are capable of learning about topics in detail, and trust me, they will have lots of questions! It is important that I am answering their questions to the best of my ability based on up to date, factual research.
Let me give you a fun mocktail fact to bring with you to the pollination party. Why do giraffes have long necks? (I’ll give you a second to think and hopefully you did not skim ahead like your favorite sparkler in the classroom always does). You probably said it’s because they need long necks to reach the tall trees in their environment, but you and I were both wrong. There is greater evidence that giraffes actually have long necks as an evolutionary adaptation related to reproduction; stronger and longer necks make male giraffes better fighters, when swinging their necks in battles to entice the attention of possible female-giraffe mates. You should go Google giraffe fights right now because if you were like me, you have never seen this before. I went to a few local bookstores after learning this to check out science books in the children’s section for this giraffe fact. Out of the ten books I picked up from the nonfiction section, all ten said giraffes have long necks to reach the leaves on tall trees. For me, this highlights the importance of doing content research; the reason you are reading this right now is to be an expert on these topics! It also points me towards making sure I am picking high-quality science or nonfiction texts to share with my students, where the science is accurate or most-reflective of current research.
Pollination is a very complex system, but there are ways to make it understandable for our students both in their real environment and through the use of visuals, like picture books, models, drawings, and photographs. Many of its structures are not visible to the naked eye and require specific scientific content knowledge to explain. I think it is important for me as a to discuss pollination in age-appropriate language, but I do not want to oversimplify it as a system for them. Building curious scientists starts in kindergarten!
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