Each of the three rounds demonstrates a different concept. There is ample possibility for this game to be modified to illustrate additional concepts in ecology and evolution, particularly incorporating the fitness effects on pollinators see Table 1 for key concepts and definitions. Students in the flower group aim to receive as many pollen grains as possible, and students in the pollinator group aim to give away all their pollen grains.
Pollinators are each given five yellow circles that represent pollen grains, and an assigned pollinator type e. Discussion questions and answers for each round of the game are provided at the end of each round. Students receive pollen grains. Students hand out one pollen grain during each round of the game. Flower signs for approximately half the students Figure 1A ; flowers can be printed in the number or color equivalent to the number of types of candy used [see below] or colored in class, before Round 3.
Pollen grains and pollinator type e. Score cards for each student Figure 2. Score card for keeping track of individual and population classroom fitness achieved during each round of the Pollination Game. Pollinators are given a short time 30 seconds to 1 minute to visit flowers. On each visit a pollinator can give only one pollen grain to an individual flower.
Tally the score. Each flower and pollinator marks on their score sheet how many pollen grains they received or gave. Note: It is possible for flowers to acquire more than five pollen grains. On their score cards, students record the class average for pollen grains received or donated. Answer: The pollen grains represent the male fitness component of flowering plants in nature because pollinators transport the male reproductive unit, pollen; whereas the flower represents the female fitness component that receives the pollen.
In nature, most flowering plants will optimize female and male fitness by both receiving and donating as many pollen grains as possible. Plants that had flowers with the most pollen grains had the highest female fitness. Answer: The more pollen grains a flower received, the more ovules that could be fertilized to make seeds. The plant with the most seeds will pass on its genes more and have high fitness. Pollinators that gave away all their pollen grains had higher plant male fitness than those that did not give away all their pollen grains.
Answer: In this exercise, pollinators represent the male side of plant fitness, and plants that donate all their pollen grains to receptive flowers fertilize more ovules. They are more likely to pass their genes on through the seeds and therefore have higher fitness than those plants that do not donate all their pollen grains. Reset the game. Each flower now pairs up with a pollinator. With an odd number of students, someone can become the observer.
While the flower will want to collect as many pollen grains as possible, the pollinator will have the goal of delivering all five pollen grains during the action phase. First, students are given a short time 2—5 minutes to strategize ways to maximize fitness. The team should also think about the best way for the pollinator to deliver pollen grains efficiently. They should write short notes about their strategy on their scorecards. Once everyone is ready, pollinators are given about 2 minutes to visit flowers.
On each visit, a pollinator can give only one pollen grain to an individual flower. Each flower and pollinator team gets back together and tallies their score on their score sheet. The class as a whole should calculate the average of all the team scores; this will serve as a comparison to the average score when accounting for only one component of fitness. Why did the flower and pollinator teams combine scores? Answer: This more accurately represents fitness in nature — the female component via seeds that will be formed after receiving pollen grains and the male component via pollen donation to sire seeds.
Many flowering plants are actually hermaphroditic, and therefore individuals are capable of achieving fitness through male and female success. Many worms, mollusks, and fish are hermaphroditic as well Barrett, Did students optimize fitness by visiting or being visited by near neighbors, or did pollinators move around the room a lot? Why might this matter?
Answer: In nature, near neighbors of sessile organisms are more likely to be related. By exchanging genetic material with neighbors, the chance of inbreeding is very high. Inbreeding has negative consequences due to inbreeding depression. With inbreeding, rare deleterious alleles can be expressed that have severe negative impacts on fitness.
Thinking about the last question: What could happen if a pollinator visited the flowers with pollen from a completely different population? Would this increase or decrease the fitness of the flowers that the pollinator visited?
Answer: It could be either. Pollen from another population could introduce novel genetic variation through gene flow that would benefit the offspring of any seeds that it sires. On the other hand, pollen from another population may introduce genes that are not adapted to the conditions that this population is experiencing.
For example, the pollen could contain genes that are better adapted to cold conditions, and the present population may be in a warm environment. Now, all the flowers whose team has a high score greater than the average score for the class should raise their hands.
What if all of the plants with these flowers also carried a gene that resulted in smaller leaves? What would the next generation look like, and what natural evolutionary concept does this exemplify? Answer: The next generation would have a greater proportion of individuals with small leaves. This is an example of indirect selection , whereby the gene that changed in frequency was not under direct selection but increased in prevalence due to an association to a trait that was under direct selection.
Flowers are asked to pick a spot in the room and remain stationary. After the flowers are given candy, the pollinator types are each assigned a candy color preference. For example: bats prefer green, bees prefer yellow, and hummingbirds prefer red. Just make sure each pollinator has a single color preference. Pollinators are given 2 minutes to visit flowers with a reward of their color preference. On each visit, a pollinator can give only two pollen grains to an individual flower.
But in exchange for pollen grains, the flowers can give the pollinators one piece of candy per pollen grain. As a class, students calculate the average number of pollen grains received by color reward type and pollen grains donated by pollinator type.
Did some plants achieve much higher female fitness through the flowers in this round than in the other rounds? Answer: Pollinators showed preference for certain flowers because they offered rewards. In this game, the candy is analogous to flowers that offer different kinds of nectar in nature.
Flowers that offered no reward may not have been visited much or at all. If flowers that offered one type of reward e. Answer: There would be a great proportion of flowers that offered that reward, because more of those genes were passed on to the offspring. Plants offering that reward would have much higher female fitness.
Pollinator preference acts as a selective force for flowers with certain floral rewards. What would happen if only one type of pollinator was present? Answer: If the pollinator had a strong preference as in this exercise , the flowers with that type of reward would receive more pollen grains and those individuals would have greater female fitness. If plants with flowers that have more rewards to offer can achieve high fitness, then why don't all flowers offer lots and lots of the best rewards?
Answer: There is a resource trade-off between generating rewards like nectar and also having enough resources to produce viable seeds. This is known as resource allocation. When setting up this added level of complexity, the instructor should carefully consider how individual pollinators can learn to associate floral rewards with specific floral traits versus the population of pollinators evolving in response to plant-mediated selection e. This scenario would provide an excellent opportunity to discuss the difference between learned and inherited traits in terms of pollinator evolution.
This will likely result in this pollinator type easily donating lots of pollen grains. Discuss the trade-offs between generalizing or specializing from the plant perspective: Generalist pollinators are often less efficient pollinators than specialists, which can lead to the evolution of floral traits and rewards for specialist pollinators that thereby monopolize those rewards Larsson, Give out candy to flowers again, but greatly skew the proportions of colors that are given to the students.
Or give some flowers far more candy or multiple types of candy. All these setups will create scenarios in which the next generation will be influenced by the pollinator preference. This exercise is best done in groups but will work for pairs or individuals as well.
Students are asked to synthesize the concepts learned in the game to develop hypotheses on what combinations of flowers and their associated pollinator s would result in high fitness for the flowering-plant population. Students should consider resources needed to supply rewards or maintain showy, large flowers. For each flower, students should consider: How many ovules seeds can it produce? What is the habitat of the population? Are there other species competing for pollen or helping to attract pollinators?
After creating the flower and pollinator combination, each group can present its rationale to the class. Students can then debate the pros and cons of each scenario and even run the exercise again to test these hypotheses the next week and collect data to present results on their hypotheses.
Recipient s will receive an email with a link to 'Population Evolution: The Pollination Game' and will not need an account to access the content. Sign In or Create an Account. User Tools. Sign In. Skip Nav Destination Article Navigation. Close mobile search navigation Article navigation.
Volume 78, Issue 2. Previous Article Next Article. Pollination Biology as an Example. Game Setup. The Pollination Game. Most modern angiosperms are classified as either monocots or eudicots, based on the structure of their leaves and embryos. Basal angiosperms, such as water lilies, are considered more ancestral in nature because they share morphological traits with both monocots and eudicots.
Angiosperms produce their gametes in separate organs, which are usually housed in a flower. Both fertilization and embryo development take place inside an anatomical structure that provides a stable system of sexual reproduction largely sheltered from environmental fluctuations.
With about , species, flowering plants are the most diverse phylum on Earth after insects, which number about 1,, species. Flowers come in a bewildering array of sizes, shapes, colors, smells, and arrangements. Most flowers have a mutualistic pollinator, with the distinctive features of flowers reflecting the nature of the pollination agent. The relationship between pollinator and flower characteristics is one of the great examples of coevolution. Following fertilization of the egg, the ovule grows into a seed.
The surrounding tissues of the ovary thicken, developing into a fruit that will protect the seed and often ensure its dispersal over a wide geographic range. Like flowers, fruit can vary tremendously in appearance, size, smell, and taste. Tomatoes, green peppers, corn, and avocados are all examples of fruits. Along with pollen and seeds, fruits also act as agents of dispersal.
Some may be carried away by the wind. Many attract animals that will eat the fruit and pass the seeds through their digestive systems, then deposit the seeds in another location. Cockleburs are covered with stiff, hooked spines that can hook into fur or clothing and hitch a ride on an animal for long distances.
The cockleburs that clung to the velvet trousers of an enterprising Swiss hiker, George de Mestral, inspired his invention of the loop and hook fastener he named Velcro. Phylogeny is the science that describes the relative connections between organisms, in terms of ancestral and descendant species. Phylogenetic trees, such as the plant evolutionary history shown in Figure , are tree-like branching diagrams that depict these relationships.
Species are found at the tips of the branches. Each branching point, called a node, is the point at which a single taxonomic group taxon , such as a species, separates into two or more species. Phylogenetic trees have been built to describe the relationships between species since the first sketch of a tree that appeared in Darwin's Origin of Species. Traditional methods involve comparison of homologous anatomical structures and embryonic development, assuming that closely related organisms share anatomical features that emerge during embryo development.
Some traits that disappear in the adult are present in the embryo; for example, an early human embryo has a postanal tail, as do all members of the Phylum Chordata. The study of fossil records shows the intermediate stages that link an ancestral form to its descendants. However, many of the approaches to classification based on the fossil record alone are imprecise and lend themselves to multiple interpretations.
As the tools of molecular biology and computational analysis have been developed and perfected in recent years, a new generation of tree-building methods has taken shape. The key assumption is that genes for essential proteins or RNA structures, such as the ribosomal RNAs, are inherently conserved because mutations changes in the DNA sequence could possibly compromise the survival of the organism. DNA from minute samples of living organisms or fossils can be amplified by polymerase chain reaction PCR and sequenced, targeting the regions of the genome that are most likely to be conserved between species.
Once the sequences of interest are obtained, they are compared with existing sequences in databases such as GenBank, which is maintained by The National Center for Biotechnology Information. A number of computational tools are available to align and analyze sequences. Sophisticated computer analysis programs determine the percentage of sequence identity or homology.
Sequence homology can be used to estimate the evolutionary distance between two DNA sequences and reflect the time elapsed since the genes separated from a common ancestor. Molecular analysis has revolutionized phylogenetic trees. In some cases, prior results from morphological studies have been confirmed: for example, confirming Amborella trichopoda as the most primitive angiosperm known. However, some groups and relationships have been rearranged as a result of DNA analysis.
Seed plants appeared about one million years ago, during the Carboniferous period. Two major innovations were seeds and pollen. Seeds protect the embryo from desiccation and provide it with a store of nutrients to support the early growth of the sporophyte. Seeds are also equipped to delay germination until growth conditions are optimal.
Pollen allows seed plants to reproduce in the absence of water. The gametophytes of seed plants shrank, while the sporophytes became prominent structures and the diploid stage became the longest phase of the life cycle. In the gymnosperms, which appeared during the drier Permian period and became the dominant group during the Triassic, pollen was dispersed by wind, and their naked seeds developed in the sporophylls of a strobilus. Angiosperms bear both flowers and fruit. Flowers expand the possibilities for pollination, especially by insects, who have coevolved with the flowering plants.
Fruits offer additional protection to the embryo during its development, and also assist with seed dispersal. Angiosperms appeared during the Mesozoic era and have become the dominant plant life in terrestrial habitats. Which of the following structures widens the geographic range of a species and is an agent of dispersal? The Triassic Period was marked by the increase in number and variety of angiosperms.
Insects also diversified enormously during the same period. Can you propose the reason or reasons that could foster coevolution? Both pollination and herbivory contributed to diversity, with plants needing to attract some insects and repel others. What role did the adaptations of seed and pollen play in the development and expansion of seed plants?
Seeds and pollen allowed plants to reproduce in absence of water. This allowed them to expand their range onto dry land and to survive drought conditions. Student View. Preview Copy. Save Please log in to save materials. Show More Show Less. Plant timeline. Various plant species evolved in different eras.
Seed fern leaf. This fossilized leaf is from Glossopteris , a seed fern that thrived during the Permian age — million years ago. Schmidt, USGS Fossil records indicate the first gymnosperms progymnosperms most likely originated in the Paleozoic era, during the middle Devonian period: about million years ago. This boreal forest taiga has low-lying plants and conifer trees. Pollen fossils. The pollen is magnified 1, times.
Ficus imprint. This leaf imprint shows a Ficus speciosissima , an angiosperm that flourished during the Cretaceous period. Plant phylogeny. This phylogenetic tree shows the evolutionary relationships of plants. Show Hint Hint: D. Show Hint Hint: A.
In which of the following geological periods would gymnosperms dominate the landscape? Carboniferous Permian Triassic Eocene present. Show Hint Hint: C. Show Hint Hint: Both pollination and herbivory contributed to diversity, with plants needing to attract some insects and repel others.
Show Hint Hint: Seeds and pollen allowed plants to reproduce in absence of water. Forgot password? Show password.
Купить Подробнее 300,00 грн. Купить Подробнее 815,00 грн. Бесплатная доставка от 400 грн.
Купить Подробнее 1 350,00. Интернет магазин косметики, тестера 78-30-263 063 304-35-75 Продуктов в корзине: пожаловать в веб магазин грн. Купить Подробнее 300,00 грн. Интернет магазин 25,00 грн. Купить Подробнее 25,00 грн.