User:Kraft.119/sandbox

This is the Sandbox of Quentin Kraft. Email: kraft.119@osu.edu Class: EEOB 3310 Recitation: Thursday- 4:10

Annotated Bibliography Quentin Kraft Posed Question: Do animals adapt to plant chemical defenses?

Levin, D. (1976). The Chemical Defenses of Plants to Pathogens and Herbivores (Vol. 7, pp. 121-159). Annual Reviews.

This shows that plants do in fact use chemicals in defense to keep herbivores away and keep herbivores from feeding on them.

Wittstock, U. (2004). Successful herbivore attack due to metabolic diversion of a plant chemical defense. Proceedings of the National Academy of Sciences, 4859-4864.

This journal entry shows that herbivores (in this case, the cabbage white butterfly) have a means of benefitting from the chemical defenses shown by plants.

Rosenthal, G. (1991). Herbivores: Their interactions with secondary plant metabolites. (2nd ed., Vol. 2, pp. 450-455). San Diego: Academic Press.

This provides a study explicitly showing the back and forth coevolution between herbivores and plants.

Jongsma, M. (1997). The adaptation of insects to plant protease inhibitors. Journal of Insect Physiology, 43(10), 885-895.

This journal entry gives another prime example of herbivores (in this case insects) affected by a chemical defense (plant protease inhibitors), however the insect has adapted to not be affected in a negative way by this defense mechanism.

Mallet, J., & Porter, P. (1992). Preventing insect adaptation to insect-resistant crops: Are seed mixtures or refugia the best strategy? Department of Entomology, Mississippi State University, 165-169.

Although this source is attempting to show the best way to prevent the adaptations of insects (herbivores) to resistant plants, this no less shows the adaptations in which these insects undergo in the first place, to combat chemical defenses.

Wikipedia Assignment 2:

https://en.wikipedia.org/wiki/Parasitism Suggestion 1: Add to the fact that "host defenses coevolve in response to attacks by parasites". The article could suggest that parasites adapt in response to host defenses specifically. But the article should specify if they do. And if they do, how so? Suggestion 2: Although my main focus is primarily based on the defenses and evolutionary aspects of parasitism, after reading the page, there are some areas where examples should be given. An example of how "parasites evolve in responses to their host's defenses" may aid in presenting the information more clearly.

https://en.wikipedia.org/wiki/Herbivore_adaptations_to_plant_defense Suggestion 3: Under the "herbivore use of plant chemicals" category, the author of the Wiki-page should define and give examples of secondary metabolic products. This would describe this process to the reader more clearly.

Sentence+Citation: Several species of insects sequester and deploy plant chemicals for their own defense.

Final Draft: Adaptation of Animals in Response to Plant Chemical Defenses Over the course of time plants have evolved to develop many sorts of defenses to animal interactions with them. Symbiotic relationships between plants and animals can be seen everyday. A white-tailed deer will eat the apples off of apple trees, different species of birds use trees and cacti as their homes, and honey bees will use the pollen from a flower for its own consumption, and in the process pollinate other flowers. However, sometimes these relationships are harmful to the plant, establishing a parasitic relationship between the two. It is hypothesized that animals, which utilize the resources of plants for their own benefit, select for a plant that can give off a defensive response (Rhoades, 1985). With this, plants with different defensive mechanisms have evolved. Examples of plant defenses that can be seen today consist of chemical defenses such as the production of nitrogen compounds that can have inhibiting effects on enzymes in animals, mechanical defenses such as thorns on the stems of thorn bushes, and indirect defenses such as induced emission of volatiles upon herbivory (Levin, 1976). There is at least one kind of defense in almost all plants. The continuous evolution of plants and their defenses establishes a question of its own: Do animals, in turn, adapt to plant chemical defenses? It may not be as easy to tell whether this is occurring because plants aren’t attacking animals and forcing rapid evolution. If this type of evolution were to occur, it would most likely occur on a cellular scale and would have to be observed over periods of time. As stated in the text of Levin’s The Chemical Defenses of Plants to Pathogens and Herbivores, many types of plant defense mechanisms affect many animals, whether they are mechanical, chemical, or indirect (Levin, 1976). One example is the excretion of toxic compounds of some plants in defense against herbivorous mammals. Mammals that consume a plant and become poisoned by it learn not to eat from this plant, thus indicating success of the defense mechanism. However, there have been cases in which some species are able to oxidize poisonous compounds. These species are able to continue to consume the plant because they are unaffected by its excreted poisonous compounds. Likewise, herbivorous insects have been seen to detoxify toxins in a similar manner via oxidations, reductions and conjugations of the compounds (Levin, 1976). In other insects, detoxification of poisonous compounds does not take place, however the sequestering, or utilizing, of these compounds for their own defense takes place. One example of this is in the Chrysolina beetle. This beetle feeds on the Hypericum plant, which has developed a chemical defense in the form of polyphenol hypericin (Levin, 1976). This is a type feeding inhibitor. However, the beetle has been shown to store the polyphenol in the gut, which may in fact render it distasteful to predators of the beetle (Levin, 1976). The previous examples referring to the ability of animals to be unaffected by plant defense mechanisms may suggest this came to be by means of adaptation to these defense mechanisms by natural selection. If this were the case, the insects unaffected by plant defenses would be better suited for their environment than their ancestors or even other insects within the same environment. In order to show that this may be the case, the establishment of co-evolution between plants and animals must be established. In the text of Rosenthal’s Herbivores: Their interactions with secondary plant metabolites, Rosenthal shares the results of an experiment that tests the correlation of the insect-plant systems in California. The findings showed that many insect-plant systems show a positive correlation between the number of insect species associated with plant species within the plants geographical range (Rosenthal, G. 1991). Plants that were historically older in the geographical region had a higher correlation than plants that were more recently introduced to this region. These findings support that coevolution had occurred within this insect-plant system (Rosenthal, G. 1991). The previous coevolution between animals and plants can be better described by the ‘Red Queen’ hypothesis. The ‘Red Queen’ hypothesis states that competitive success and failure evolve back and forth through organizational learning. An organism facing competition with another organism, through selection, eventually has an increase in performance, which increases its competitive success and forces its competitor to increase its performance through selection as well, thus creating an “arms race” between the two (Barnett & Hansen). If animals were to evolve because of plant defenses, this would be because plants first had to increase their competitive performance due to animal competitive success. To add to this point, an experiment was performed on the Pieris rapae or cabbage white butterfly to see if it had evolved in correspondence to a plant defense mechanism. Glucosolinates are highly studied defensive compounds that are found in several plant families (Wittstock, 2004). They are present with another compound called myrosinases and together they are hydrolyzed by herbivorous insects. The two compounds are highly toxic. However, P. rapae larvae have redirected their digestive processes so the poisonous components are excreted through their feces. This allows the larvae to completely avoid the toxic effects of the compounds. Researchers found that the P. rapae alone had developed a nitrile-specifier protein as a counter-adaptation that allows for the avoidance of hydrolyzing the poisonous components when consuming it through plant consumption (Wittstock, 2004). This finding showed that animals could evolve in response to plant defense mechanisms and gives a perfect example of coevolution in the context of the ‘Red Queen’ hypothesis. A similar example to the circumvention of the effects of glucosolinates on insect herbivores is the ability for insect herbivores to be unaffected by protease inhibitors. Proteases are proteins present in the gut of all herbivore insects. Their major role is their ability to help digest food: plant tissue. On the other hand, most types of plants have protease inhibitors. Protease inhibitors are present within the plant tissues and they inactivate animal proteases. This leads to an array of issues for the insect, such as reduced feeding, weight gain, and prolonged larval developmental time. Protease inhibitors are reduced in tobacco plant tissue that has been unaffected by insect consumption. However, in young tissue and tissue that has been recently affected by insect consumption, the levels of protease inhibitors are very high. This is a signal of co-evolution between plants and the insects feeding on it. Tests on different kinds of herbivorous insects - S. exigua and L. decemlineata- took place, where they were provided diets containing protease inhibitors. Results proved that these insects had developed ways to counter the effects of the protease inhibitors (Jongsma, 1997). The insects had developed protease that was unaffected by plant inhibitors fed to the insects. The insects also gained the ability of proteolytic degradation of protease inhibitors in addition to the ability to acquire mutations rendering their protease to be less sensitive to protease inhibitors. The gene regulation of the protease inhibitor- insensitive proteases showed to be up-regulated to compensate for the inhibited proteases during this experiment (Jongsma, 1997). This shows that the effect of protease inhibitors selected for competitive success in the insects. Following coevolution and the ‘Red Queen’ hypothesis, the competitive success of the insects increased due to their adaptations. The coevolution of insects with plants is being studied a lot today when it comes to transgenic crops. Transgenic crops are genetically modified crop plants, which produce their own insecticide (Tabashnik, et al.). Even so, insects are evolving faster than ever before in the presence of insecticides and herbicides. Herbicide and insecticide resistance is a battle that scientists are trying to find the solution for. A study was performed to determine whether a larger decrease in insect resistance would result from planting the transgenic crops in ‘refugia’. The term refugia means the planting of plants with the insecticide in separate fields than plants without the insecticide present. In other words, plants with and without the insecticide were planted in the same field. This experiment displays the evolution of insects in response to plant defense mechanisms from a different perspective: what will make the insects adapt the least. In this case the strategy that resulted in the insects adapting the least was measured by which fields had the better survival rate. Just as with other compounds produced by the plants that inhibited the insects, this will lead to coevolution between both plant and insect. For the fields planted in ‘refugia’ there was an increase in number of generations of insects over time compared to that of the seed mixture (Mallet & Porter, 1992). However, adding toxin-free plants to a seed mix can hasten insect resistance (Mallet & Porter, 1992). This was found to counteract reduced selection, which will then lead to the adaptation to these insecticides. This being the case seed mixture is destined for failure if attempting to decrease amount of evolution of insects due to insecticides, because of the insects’ rapid evolution to plant defenses. After observing all of these experiments, it can be concluded that plants adapt to herbivore intervention, and at the same time, herbivores adapt to the chemical defense mechanisms of plants. Their symbiotic relationship creates a pattern of coevolution with one another. The Red Queen Hypothesis is seen all kinds of organisms on the globe and it seems to be taking affect between plants and animals as well. This coevolution leads to back and forth shift in competitive success, which in turn leads to evolution of either animals or plants in correspondence with the other. Ultimately one organism will be selected for based on its beneficial traits and genes. These could arise via mutation, genetic variation, and natural selection.

References Barnett, W., & Hansen, M. n.d. The red queen in organizational evolution. Strategic Management Journal. 139-157. Jongsma, M. 1997. The adaptation of insects to plant protease inhibitors. Journal of Insect Physiology. 43, 885-895. Levin, D. 1976. The Chemical Defenses of Plants to Pathogens and Herbivores. Annual Reviews. 7, 121-159. Mallet, J., & Porter, P. 1992. Preventing insect adaptation to insect-resistant crops: Are seed mixtures or refugia the best strategy? Department of Entomology. Mississippi State University. 165-169. Rhoades, D. 1985. Offensive-Defensive Interactions between Herbivores and Plants: Their Relevance in Herbivore Population Dynamics and Ecological Theory. The American Naturalist. 125, 205-238. Rosenthal, G. 1991. Herbivores: Their interactions with secondary plant metabolites. San Diego. Academic Press. 2, 450-455. Tabashnik, B., Rensburg, J., & Carrière, Y. n.d. Field-Evolved Insect Resistance to Crops: Definition. Theory, and Data. Journal of Economic Entomology. 2011-2025. Wittstock, U. 2004. Successful herbivore attack due to metabolic diversion of a plant chemical defense. Proceedings of the National Academy of Sciences. 4859-4864.

Wikipedia Page EDIT: https://en.wikipedia.org/wiki/Herbivore_adaptations_to_plant_defense

The coevolution that occurs between plants and herbivores that ultimately results in the speciation of both can be further explained by the Red Queen hypothesis. This hypothesis states that competitive success and failure evolve back and forth through organizational learning. The act of an organism facing competition with another organism ultimately leads to an increase in the organism's performance due to selection. This increase in competitive success then forces the competing organism to increase its performance through selection as well, thus creating an "arms race" between the two species. Herbivores evolve due to plant defenses because plants must increase their competitive performance first due to herbivore competitive success. An important enzyme produced by herbivorous insects is protease. The protease enzyme is a protein in the gut that helps the insect digest its main source of food: plant tissue. Many types of plants produce protease inhibitors, which inactivate proteases. Protease inactivation can lead to many issues such as reduced feeding, prolonged larval development time, and weight gain. However, many insects, including S. exigua and L. decemlineatu have been selected for mechanisms to avoid the effects of protease inhibitors. Some of these mechanisms include developing protease enzymes that are unaffected by the plant protease inhibitors, gaining the ability to degrade protease inhibitors, and acquiring mutations that allow the digesting of plant tissue without its destructive effects. One major example of herbivorous behavioral adaptations deals with introduced insecticides and pesticides. The introduction of new herbicides and pesticides only selects for insects that can ultimately avoid or utilize these chemicals over time. Adding toxin free plants to a population of transgenic plants, or genetically modified plants that produce their own insecticides, has been shown to minimize the rate of evolution in insects feeding on crop plants. But even so, the rate of adaptation is only increasing in these insects.