Bullock Co-evolutionary design techniques are discussed Janzen Ehrlich and Raven (1) This is coevolution, a term that was originally coined by Ehrlich and Raven after observing plant-herbivore interactions. (2) The term is usually attributed to Ehrlich and Raven's study of butterflies on plants (1964) but the term was used by others prior to 1964 and the idea was very present in the Origin of Species. Ehrlich and Raven documented the association between species of butterflies and their host plants noting that plants' secondary compounds (noxious compounds produced by the plant) determined the usage of certain plants by butterflies. The implication was that the diversity of plants and their "poisonous" secondary compounds contributed to the generation of diversity of butterfly species. (3) Ehrlich, P. R. &. P. H. Raven (1964). Butterflies and plants: a study in coevolution. Evolution 18, 586-608. First discussion of gcoevolutionh, however, without explicit definition, and lists butterfly and host plant associations. Postulates an evolutionary arms race creating new chemical defense/diversification in plants. === (1) === http://www.geology.ucdavis.edu/ The Department of Geology University of California Davis (UCDavis), California => http://www.geology.ucdavis.edu/~cowen/HistoryofLife/evolutionlinks.html Introduction This series of pages is designed to expand your knowledge and interest in the biology of organisms and their evolutionary history. Increasingly, as biology departments expand their curricula toward cellular and molecular biology and genetics, the biology of organisms gets short-changed. Certainly there are exciting, fundamental, and money-making advances in cellular and molecular biology, but that does not mean that organismal biology is stagnant or uninteresting. => http://www.geology.ucdavis.edu/~cowen/HistoryofLife/coevolutionadv.html Coevolution Species evolve in ways that improve (or at least maintain) their viability. Communities, it seems, do not have the same process: there is no evolution of a community or ecosystem as a unit. But species may evolve in ways that are primarily influenced by ecology: by their relationship with one or a few other species, and in turn these others evolve also. <> There are variations within coevolution: one species may converge evolutionarily on another that changes little (for example, in some forms of mimicry). Two species may diverge until they no longer interact (character displacement, maybe driven by niche partitioning). Species may respond to such a broad range of other species that "coevolution" is diffused into a general reaction to the biotic environment, or "evolution": examples here include the response of herbivores to the whole ecosystem represented in the word "savanna," or the intricate ways of life that have evolved within "reef" ecosystems. Nevertheless, the concept of coevolution is very important, and in a broad sense may underlie some major adaptive radiations. Models of rapid speciation depends heavily on the chance events that split off isolated populations. These events, by their very nature, tend to be aspects of the physical environment, such as changes in climate or topography. But organisms interact with other organisms, which form part of their biotic environment. Would our view of the evolutionary process change if we considered biotic aspects too? There are two broad categories of coevolution: antagonistic and mutualistic. (Enlarging on this theme: for each there must be a balance or an asymmetry such that one species is evolutionarily the "prey" and the other is the "pursuer", except in the case of runaway selection for mutual advantage. It would be to the advantage of the "prey" or "target" species to escape by quantum speciation, except that I don't see at the moment how the species could accomplish that. In most cases of very strongly linked biotic coevolution, one species is likely to track another very closely. Thus in coevolution, there is probably a built-in bias toward gradual evolution, in both or all species involved. Now it depends how coevolutionarily linked any given community is: there's no need to suppose that the links are simple. Perhaps in a biotically interlinked community with strong internal biotic relationships, the dominant style of evolution could be coevolutionary and gradual. Perhaps evolution could be more punctuated in loosely linked communities. Maybe it depends whether biotic interactions or physical changes are dominant for particular groups of organisms at particular times and in particular ecosystems.) If a major selective force on a species is its relationship with another species, then one can envisage an process in which they evolve toward a mutual evolutionary stability. In fact, if the relationship is adversary, such as a predator-prey relationship, or a parasite-host relationship, achieving mutual stability is necessary for their continued coexistence. The mutual stability might take the form of character divergence so that there is no longer a coevolutionary relationship. ANTAGONISTIC COEVOLUTION Predator-prey relationships Asymmetry. There is an asymmetrical pay-off in those predator-prey relationships where the prey is killed. The predator pays for failure by short-term lack of food: it gets a second chance, usually. The prey pays for failure with its life. This asymmetry, with corresponding direct feedback into fitness, might possibly produce more visible and extreme adaptations in prey species than in predators. Bakker, in an attempt to show that coevolution is imperfect, documents an apparent failure by early Cenozoic predators to "keep up" with the advanced locomotory systems of early Cenozoic herbivores. Arms races. There is bound to be dynamic coevolution between any predators and prey that coexist for a while. One would then predict "arms races" as a natural consequence, especially in those cases where the prey is not killed (e.g. in many plant-herbivore interactions). Thus defenses may take the form of toxins, and herbivores will endeavor to "crack" the code of the toxins to make them into metabolites. If successful they may then use the toxins (monarch butterflies, opisthobranch gastropods). CASE STUDIES Grasses, silica, and hypsodonty Dinosaur body structure tracks prevalent plant height (Bakker) Insect herbivory as an impetus toward the angiosperm condition The great Cenozoic brain race (Jerison); perhaps also the great Mesozoic brain race? (Hopson). The rise of shelled organisms and the mysterious Cambrian predators The mid-Paleozoic rise of shell-crushers (Signor and Brett) The Mesozoic faunal revolution The defenses posed by shells (Kitchell) Mimicry, camouflage, and code-breaking by predators FOR FURTHER EXAMINATION The size of herbivores: other things being equal, creatures move faster at large size, and become predator-proof at larger size. (Is this the underpinning of Cope's Law? Because if the suggestion is true, predator size should then track prey size too, and most things are either predators, or prey, or both.) What is the role of predation in evolution? Stanley supposed that predation acted to promote diversity, misusing Paine's work on keystone species: actually, predation merely maintains diversity. Vermeij made a much better case for predation encouraging diversity. Lost races? Trilobites vs. fishes and/or cephalopods? Competition - often at one trophic level Character displacement and niche partitioning as an escape Convergence in characters for functional reasons Competition for parameters other than food: arms races may result CASE STUDIES The particular problems of plants, which only do one thing (Knoll) Fishes vs. cephalopods Thecodonts vs. therapsids The Great American Interchange Mammals vs. birds for carnivorous niches: Diatryma, phorusrhacids Early primates vs. rodents vs. multituberculates Competitive overgrowth on substrates Trophic amensalism (Thayer) Marine mammals vs. birds for nesting sites (Lindberg) Mimicry : is subtly antagonistic. The result is that mimics never come to outnumber their models. But by the same process, a model that is once mimicked may never be able to escape except by its own extinction. Although code-breaking takes place, we're looking at an asymmetrical evolutionary race again. Parasitism . MUTUALISTIC COEVOLUTION Mutualism must have its origins in antagonism. Pollination. Examples are birds, bats, insects, mammals. The question of the function of flowers - as dominantly male organs (Bell). Seed dispersal By all the above, plus dung beetles; larger animals and birds than make good pollinators. The dodo and the tambalocoque. Amazonian fishes. Non-human agriculture, and seduction by plants. Attine ants, acacia ants, ants and aphids. Worms and gastropods: many more suspension-feeders? Symbiosis as a modification of antagonism The savanna ecosystem. The concept of guilds of organisms. The cohesiveness of communities as a coevolutionary phenomenon (Roughgarden). Algal symbiosis as a special case underlying the whole series of reef ecosystems through time. The corollary that breakdown means BREAKDOWN. The fruits the gomphotheres ate. Return to Evolution topics Return to Geology Department home page === (2) === COEVOLUTION -------------------------------------------------------------------------------- First some definitions: coevolution is a change in the genetic composition of one species (or group) in response to a genetic change in another. More generally, the idea of some reciprocal evolutionary change in interacting species is a strict definition of coevolution. At first glance (or thought), it might seem that everything is involved in coevolution. This assumption might stem from the fact that virtually all organisms interact with other organisms and presumably influence their evolution in some way. But this assumption depends entirely on ones definition of the term Coevolution. The term is usually attributed to Ehrlich and Raven's study of butterflies on plants (1964) but the term was used by others prior to 1964 and the idea was very present in the Origin of Species. Ehrlich and Raven documented the association between species of butterflies and their host plants noting that plants' secondary compounds (noxious compounds produced by the plant) determined the usage of certain plants by butterflies. The implication was that the diversity of plants and their "poisonous" secondary compounds contributed to the generation of diversity of butterfly species. Here we have a very general observation of one group of organisms having an influence on another group of organisms. Is this coevolution? Some would argue that it is not good evidence for coevolution because the reciprocal changes have not been documented clearly. Like the issue of defining an adaptation, we should not invoke coevolution without reasonable evidence that the traits in each species were a result of or evolved from the interaction between the two species. Lets consider plants and insects: there is little evidence to determine whether plants' secondary compounds arose for the purpose of preventing herbivores from eating plant tissue. Certain plants may have produced certain compounds as waste products and herbivores attacked those plants that they could digest. Parasites and hosts: when a parasite invades a host, it will successfully invade those hosts whose defense traits it can circumvent because of the abilities it caries at that time. Thus presence of a parasite on a host does not constitute evidence for coevolution. These criticisms are quite distinct from the opportunity for coevolution once a parasite has established itself on a host. The main point is that any old interaction, symbiosis, mutualism, etc. is not synonymous with coevolution. In one sense there has definitely been "evolution together" but whether this fits our strict definition of coevolution needs to be determined by careful 1) observation, 2) experimentation and 3) phylogenetic analysis. The classic analogy is the coevolutionary arms race: a plant has chemical defenses, an insect evolves the biochemistry to detoxify these compounds, the plant in turn evolves new defenses that the insect in turn "needs" to further detoxify. At present the evidence for these types of reciprocal adaptations is limited, but the suggestive evidence of plant animal interactions is widespread. An important point is the relative timing of the evolution of the various traits that appear to be part of the coevolution. If the presumed reciprocally induced, sequential traits actually evolved in the plant (host) before the insect (parasite) became associated with it, we should not call it coevolution. See different example figs. 22.6-22.7, pgs. 621-622 + text. There are a variety of different modes of coevolution. In some cases coevolution is quite specific such as those between two cellular functions. The endosymbiont theory proposes that current day mitochondria and chloroplasts were once free-living unicellular individuals. These cells entered the cytoplasm of other cells, an example of the general phenomenon of endosymbiosis. Current-day mitochondrial and chloroplast genomes are much smaller than the genome sizes of their presumed free-living ancestors. Some of this reduction in genome size is due to the transfer of genes from organelle genomes to the nuclear genome. Thus, being in the cellular environment has influenced the evolution of organelle genomes. There is evidence that the faster rate of evolution of animal mitochondrial DNA has accelerated the rate of evolution of some of the nuclear genes that function in the mitochondria. Thus there is some evidence for reciprocal phenomena Other modes of coevolution involve competitive interaction between two specific species. The Plethodon salamander study is a good example: two species are competing: in the Great Smoky mountains the two species compete strongly as evidenced by the fact that each species will increase population size if the other is removed. Here there is a clear reciprocal interaction between the two populations (species), each affecting the other. [The role of competition between species, the coevolutionary responses to this competition and the consequences for the evolution of communities is illustrated in the Anolis lizard fauna of the Caribbean. There is coevolution because the competitive interactions between resident and invading species of Anolis involve reciprocal responses in the evolution of body size. These affect the structure of the lizard community as evidenced by the general pattern of there being a single species of lizard on each island.] Character displacement also provides and example of a pattern we might interpret as the result of coevolution. Mud snails show pattern of character displacement in sympatry due presumably to competition for food items (don't confuse this with reinforcement; the selective agent here is not reduced hybrid fitness). We might call this co evolution because both species show a shift when compared to allopatric samples of each species (mean of both ~ 3.2 in allopatry vs. ~ 4.0 and ~ 2.8 in sympatry). If only one species exhibited character displacement and you were a really picky evolutionist you might not be convinced of a reciprocal response. Another strong case is the Ant - Acacia mutualism. Here specific traits in each species appear to have evolved in response to the interaction. The ant (Pseudomyrmex species) depends on the Acacia plant for food and housing; acacia depends on ant for protection from potential herbivores (species that eat plant tissue). Specific characters of the plant appear to have evolved for the maintenance of this mutualism: 1) swollen, ~ hollow thorns (= ant home), 2) extra-floral nectaries (source of nectar outside the flower [i.e., the usual location] providing ants with food), 3) leaflet tips = Beltian bodies (= 99% of solid food for larval/adult ants). Specific characters in the ant that have evolved for the maintenance of this mutualism: 1) defense against herbivores 2) removal of fungal spores from Beltian body break-point (prevents fungal pathogens from invading plant tissues). The main point is that there are traits in both the ant and the acacia that are traits not normally found in close relatives of each that are not involved in similar mutualisms: mutualistic traits have evolved for the interaction in reciprocal fashion. See another example : fig. 22.1 & table 22.1, pg. 611. Coevolution may be considered among broad groups of taxa, so called diffuse coevolution (such as the general coevolution between plants and insects [assuming it is real]). A nice idea, but in fact the real action must be going on between pairs of species from each group. It is true that the Pierid butterflies (family Pieridae) are associated with the plant family Cruciferae, so there may be something general about each taxon that allows the coevolution to proceed. But the true reciprocal events must be mediated at the host species-insect species level. Mimicry presents a context were coevolutionary phenomena should be evident. Generally, we would expect that Mullerian mimicry would be more likely to exhibit reciprocal evolutionary patterns since both species involved are unpalatable and therefore have an opportunity to affect the evolution of each other's color patters. This does not mean that Batesian mimicry (one unpalatable model) will not involve coevolutionary phenomena, but the evolution of warning coloration is certainly going to be more asymmetrical since the palatable species will show a greater response to the state of the model than will the model show to the evolving state of the mimic. The Mullerian mimics Heliconius erato and H. melpomene. illustrate both the frequency dependent nature of mimicry and the fact that each can influence the evolution of the other. One would expect that the more abundant species would be the model in a mullerian system, since it is what the selective agent (predation) is cueing on. In general H. erato is the more abundant of the two species and H. melpomene mimics the wing patterns of H. erato. In one area of overlap of the two species, H. melpomene is the more abundant and H. erato assumes the hindwing band pattern of H. melpomene (see figure below). Thus depending on local conditions, both species are influencing the adaptive responses of the other and thus fits strict definition of coevolution. A crucial component of coevolution is phylogenetic analysis. If the cladograms of the host and the cladograms of the parasite are congruent (e.g., figs. 22.2 - 22.3, pg. 612-613) this certainly suggests coevolutionary phenomena. But again, be careful and think about it: cospeciation is just "association by descent". Have there been reciprocal phenomena?; maybe just the speciation of the host induced the speciation of the parasite and there was not parasite induced speciation of the host. One needs to know the evolutionary history before we can make firm statements about "co"evolution. === (3) === http://userwww.sfsu.edu/~efc/classes/theoretical/biblio/lowbib.htm THEORETICAL ECOLOGY Spring 2000 CANDACE LOW Perspectives on the Coevolution of Insect-Plant Interactions Armbuster, W. S. (1992). Phylogeny and the Evolution of Plant-Animal Interactions. Bioscience 42, 12-20. O Discusses the importance of historical perspectives of ecological relationships and gecophylogenetich studies. Parsimony analysis is useful but homoplasy is a natural occurrence, so how do you determine pattern association? The stronger the selective association, the less likely we can detect causality and the presence of pattern does not prove that the hypothesis is true. This article discusses the aforementioned problem and other risks and methods of testing. Berenbaum, M. R. (1983). Coumarins and caterpillars: a case for coevolution. Evolution 37, 163-179. O Discusses evolution of furanocoumarins, toxicity to insects, plant radiation into a new adaptive zone, and specialist lepidopterans that have physiological immunity and behavioral adaptations to this chemical. Examines coevolutionary mechanism between insect herbivores and plants with biosynthetic pathway of hydroxycoumarin production. This study supports the concept of reciprocal evolutionary interactions between insects and secondary plant chemistry. Berenbaum, M. R. & Zangerl, A. R. (1998). Chemical phenotype matching between plant and its insect herbivore. Proceedings of the National Academy of Sciences. USA 95, 13743-13748. O A continuation of Berenbaum (1983). The insect herbivore is the parsnip webworm, Depressaria pastinacella, and the plant host is the wild parsnip, Pastinaca sativa. Compares an "escalating arms race" model to "stable cycling" in the evolution of resistance traits of the plants. Berenbaum, M. R. & Passoa, S. (1999). Generic Phylogeny of North American Depressariinae (Lepidoptera: Elachistidae) and Hypotheses About Coevolution. Entomological Society of America 92, 971-986. O Cladistic analysis showed no evidence of congruent cladogenesis within Depressariinae. However, host shifts between unrelated host plant families, and reversions to host plant ancestors are abundant. Explanation of sequential colonization of related plant groups. Congruent cladogenesis most likely occurs within genera, not at the family or subfamily level. Ehrlich, P. R. &. P. H. Raven (1964). Butterflies and plants: a study in coevolution. Evolution 18, 586-608. O First discussion of gcoevolutionh, however, without explicit definition, and lists butterfly and host plant associations. Postulates an evolutionary arms race creating new chemical defense/diversification in plants. Faeth, S. H. (1988). Plant-Mediated Interactions between Seasonal Herbivores: Enough for Evolution or Coevolution? In Chemical Mediation of Coevolution (ed. K. C. Spencer), pp. 391-414. Academic Press, New York. O Overview of perspectives on the evolution of insect-plant interactions mediated by the host plant. Farrell, B. D., C. Mitter, and D. J. Futuyma. (1992). Diversification at the insect-plant interface. Bioscience 42, 34-42. O Reviews the following questions: What aspects of insect host use are evolutionary conservative? How old are the associations between extant insect taxa and plant? Is there evidence for the escape-and-radiation steps (Ehrlich and Raven)? To what extent does the macroevolution determine the current diversity and structure of insect-plant associations? Futuyma, D. J. (1983). Evolutionary interactions among herbivorous insects and plants. In Coevolution (ed. D. J. Futuyma and M. Slatkin), pp. 207-231. Sinauer Associates Inc., Sunderland, MA. O An informative chapter on the usefulness of phylogenetics and concepts on the history of insects and their host plants. Hunter, A. F. (1995). Ecology, Life History, and Phylogeny of Outbreak and Nonoutbreak Species. In Population Dynamics: new approaches and synthesis (ed. N. Cappuccino and P. W. Price), pp. 41-64. Academic Press, San Diego. O Uses the basis of phylogenetic relationships to compare life-history and ecological traits to answer an ecological question about outbreak and nonoutbreak insect species. Janz, N. & Nylin, S. (1998). Butterflies and plants: a phylogenetic study. Evolution 52, 486-502. O Focuses on mechanisms behind host shifts. Their results confirm that related butterflies feed on related plants (gevolutionary conservatismh). Janzen, D. H. (1980). When is it coevolution? Evolution 34, 611-612. O Redefines gcoevolutionh (Ehrlich and Raven 1964) explicitly and emphasizes the importance of reciprocity in coevolutionary relationships. Jaremo, J., Tuomi, J., Nilsson, P. & Lennartsson, T. (1999). Plant adaptations to herbivory: mutualistic versus antagonistic coevolution. Oikos 84, 313-320. O FORUM article discussing the fitness criteria in determining mutualisms in plant-herbivore systems. Explores 3 cases of plant-animal relations: mutualism, antagonism, and in between in the context of plant overcompensation Jermy, T. (1984). Evolution of host/plant relationships. American Naturalist 124, 609-630. O Discusses validity of plant-insect studies and outlines new points of view to explain evolution of various insect/host plant relationships. Makes point that many authors treat recent insect/host plant relationships as a result of coevolutionary processes, but therefs no evidence that the insect species played a role in the evolution of their plant hosts. Discusses the premises of the classic theory of insect-plant coevolution. Mathews, J. N. A. (1994). The benefits of overcompensation and herbivory: the difference between coping with herbivores and liking them. American Naturalist 144, 528-533. O Critically examines the overcompensation models of Vail (1992). Says that Vailfs predictions are conditional on the assumption that late plant reproduction depends on prior herbivory. However, the value of Vail's models is in the assumptions. Miller, J. S. & Wenzel, J. W. (1995). Ecological characters and phylogeny. Annual Review of Entomology 40, 389-415. O Supports use of phylogenetics in insect ecology to elucidate insect-host plant interactions and the evolution of mimicry and mutualisms. Describes methods, weaknesses, and alternative scenarios of cladistic results. Focuses on evolutionary scenarios of insect-plant interactions (e.g. cospeciation, colonization). Owen, D. F. & Wiegert, R. G. (1987). Leaf eating as mutualism. In Insect Outbreaks (ed. P. a. S. Barbosa, J.C.), pp. 81-95. Academic Press. O Overview of ideas on plant-herbivore relationships. Presents alternative view that plants arenft always on the defensive and that leaf-eating may be a co-evolved mutualism between plants and their herbivores. Powell, J. A. (1980). Evolution of larval food preferences in Microlepidoptera. Annual Review of Entomology 25, 135-159. O A detailed summary of Microlepidopteran larval food preferences; a precursor to Powell, et al. Powell, J.A., C. Mitter, and B. Farrell (1999). Evolution of larval food preferences in Lepidoptera, pp. 403-422. In, N.P. Kristensen (ed.) Lepidoptera, Moths and Butterflies Volume 1. Evolution, Systematics, and Biogeography. Handbook of Zoology Volume IV Arthropoda: Insecta. Walter deGruyter: Berlin. O Uses established phylogenies to map larval feeding habits and explores the patterns. Focuses on answering questions about the origin of feeding specializations and the parallel cladogenesis of host plant lineages and the insects. Roskam, J. C. (1985). Evolutionary patterns in gall midge-host associations (Diptera, Cecidmyiidae). Tidschr. Entomol. 128, 193-213. O Interesting study of host plant associations of gall midges. The radiation of this group of specialized endophytophagous insects may be the result of sequential evolution and is demonstrated with a phylogenetic analysis. Roughgarden, J. (1983). The theory of coevolution. In Coevolution (ed. D. Futuyma and M. Slatkin). Sinauer Associates Inc., Sunderland MA. O General discussion Thompson, J. N. (1983b). The use of ephemeral plant parts on small host plants: how Depressaria leptotaeniae (Lepidoptera: Oecophoridae) feeds on Lomatium grayi (Umbelliferae). Journal of Animal Ecology 52, 281-291. O Presents an analysis of how the moth utilizes an herbaceous host plant and consequences of restricting larvae to a single plant part. Uses a paired experiment to test how the larvae fared when confined to a single umbel or to a single leaf. Specialization of phytophagous insect is expected if the resources on a single plant part are sufficient for it to complete development. Asks: When does natural selection favor small size and restriction to a single plant part? Thompson, J. N. (1985). Patterns in coevolution. In Coevolution and Systematics (Ed. by A.R. Stone and D. L. Hawksworth). Clarendon Press, Oxford. O Discusses five patterns of coevolution of Umbelliferae and insects: Ehrlich-Raven; cospeciation; mixed process coevolution; arms race analogy; and population dynamics Thompson, J. N. (1989). Concepts in coevolution. Trends in Ecology and Evolution 4, 179-183. O General discussion; Presents modes of coevolution and the kinds of species interactions associated with them Vail, S. G. (1992). Selection for overcompensatory plant responses to herbivory: a mechanism for the evolution of the plant-herbivore mutualism. American Naturalist 139, 1-8. O Presents two models to test the idea of a herbivore-driven gbet-hedgingh reproductive strategy. Weintraub, J., Lawton, J. H. & Scoble, M. J. (1995). Lithinine moths on ferns - a phylogenetic study of insect-plant interactions. Biological Journal of the Linnean Society 55, 239-250. O First study where pteridophagous Lepidoptera are analysed in a phylogenetic context and contrasts the evolutionary scenarios of Mitter, et al., Thompson, Jermy. Their observed patterns support a scenario of host shifting following a single colonization event resulting in a lack of parallel cladogenesis between moth and fern phylogenies. --- PDF] Evolutionary Economic Theories of Sustainable Development ... Originally, mass balance was studied in the context of a general equilibrium framework (Ayres and Kneese 1969 ... This has been coined gco-evolutionh (Norgaard 1994; Gowdy 1994 ... SUSTAINABLE DEVELOPMENT 121 Co-evolution has become widely accepted in biology, and can be considered the result of merging ...