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16.9: Adaptive Evolution - Biology

16.9: Adaptive Evolution - Biology


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Natural selection only acts on the population’s heritable traits: selecting for beneficial alleles and thus increasing their frequency in the population, while selecting against deleterious alleles and thereby decreasing their frequency—a process known as adaptive evolution. Natural selection acts at the level of the individual; it selects for individuals with greater contributions to the gene pool of the next generation, known as an organism’s evolutionary (Darwinian) fitness.

Fitness is often quantifiable and is measured by scientists in the field. However, it is not the absolute fitness of an individual that counts, but rather how it compares to the other organisms in the population. This concept, called relative fitness, allows researchers to determine which individuals are contributing additional offspring to the next generation, and thus, how the population might evolve.

There are several ways selection can affect population variation: stabilizing selection, directional selection, diversifying selection, frequency-dependent selection, and sexual selection. As natural selection influences the allele frequencies in a population, individuals can either become more or less genetically similar and the phenotypes displayed can become more similar or more disparate.

Stabilizing Selection

If natural selection favors an average phenotype, selecting against extreme variation, the population will undergo stabilizing selection (Figure). In a population of mice that live in the woods, for example, natural selection is likely to favor individuals that best blend in with the forest floor and are less likely to be spotted by predators. Assuming the ground is a fairly consistent shade of brown, those mice whose fur is most closely matched to that color will be most likely to survive and reproduce, passing on their genes for their brown coat. Mice that carry alleles that make them a bit lighter or a bit darker will stand out against the ground and be more likely to fall victim to predation. As a result of this selection, the population’s genetic variance will decrease.

Directional Selection

When the environment changes, populations will often undergo directional selection (Figure), which selects for phenotypes at one end of the spectrum of existing variation. A classic example of this type of selection is the evolution of the peppered moth in eighteenth- and nineteenth-century England. Prior to the Industrial Revolution, the moths were predominately light in color, which allowed them to blend in with the light-colored trees and lichens in their environment. But as soot began spewing from factories, the trees became darkened, and the light-colored moths became easier for predatory birds to spot. Over time, the frequency of the melanic form of the moth increased because they had a higher survival rate in habitats affected by air pollution because their darker coloration blended with the sooty trees. Similarly, the hypothetical mouse population may evolve to take on a different coloration if something were to cause the forest floor where they live to change color. The result of this type of selection is a shift in the population’s genetic variance toward the new, fit phenotype.

Link to Learning

In science, sometimes things are believed to be true, and then new information comes to light that changes our understanding. The story of the peppered moth is an example: the facts behind the selection toward darker moths have recently been called into question. Read this article to learn more.

Diversifying Selection

Sometimes two or more distinct phenotypes can each have their advantages and be selected for by natural selection, while the intermediate phenotypes are, on average, less fit. Known as diversifying selection (Figure 1), this is seen in many populations of animals that have multiple male forms. Large, dominant alpha males obtain mates by brute force, while small males can sneak in for furtive copulations with the females in an alpha male’s territory. In this case, both the alpha males and the “sneaking” males will be selected for, but medium-sized males, which can’t overtake the alpha males and are too big to sneak copulations, are selected against. Diversifying selection can also occur when environmental changes favor individuals on either end of the phenotypic spectrum. Imagine a population of mice living at the beach where there is light-colored sand interspersed with patches of tall grass. In this scenario, light-colored mice that blend in with the sand would be favored, as well as dark-colored mice that can hide in the grass. Medium-colored mice, on the other hand, would not blend in with either the grass or the sand, and would thus be more likely to be eaten by predators. The result of this type of selection is increased genetic variance as the population becomes more diverse.

In recent years, factories have become cleaner, and less soot is released into the environment. What impact do you think this has had on the distribution of moth color in the population?

Frequency-dependent Selection

Another type of selection, called frequency-dependent selection, favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection). An interesting example of this type of selection is seen in a unique group of lizards of the Pacific Northwest. Male common side-blotched lizards come in three throat-color patterns: orange, blue, and yellow. Each of these forms has a different reproductive strategy: orange males are the strongest and can fight other males for access to their females; blue males are medium-sized and form strong pair bonds with their mates; and yellow males (Figure 2) are the smallest, and look a bit like females, which allows them to sneak copulations. Like a game of rock-paper-scissors, orange beats blue, blue beats yellow, and yellow beats orange in the competition for females. That is, the big, strong orange males can fight off the blue males to mate with the blue’s pair-bonded females, the blue males are successful at guarding their mates against yellow sneaker males, and the yellow males can sneak copulations from the potential mates of the large, polygynous orange males.

In this scenario, orange males will be favored by natural selection when the population is dominated by blue males, blue males will thrive when the population is mostly yellow males, and yellow males will be selected for when orange males are the most populous. As a result, populations of side-blotched lizards cycle in the distribution of these phenotypes—in one generation, orange might be predominant, and then yellow males will begin to rise in frequency. Once yellow males make up a majority of the population, blue males will be selected for. Finally, when blue males become common, orange males will once again be favored.

Negative frequency-dependent selection serves to increase the population’s genetic variance by selecting for rare phenotypes, whereas positive frequency-dependent selection usually decreases genetic variance by selecting for common phenotypes.

Sexual Selection

Males and females of certain species are often quite different from one another in ways beyond the reproductive organs. Males are often larger, for example, and display many elaborate colors and adornments, like the peacock’s tail, while females tend to be smaller and duller in decoration. Such differences are known as sexual dimorphisms (Figure 3), which arise from the fact that in many populations, particularly animal populations, there is more variance in the reproductive success of the males than there is of the females. That is, some males—often the bigger, stronger, or more decorated males—get the vast majority of the total matings, while others receive none. This can occur because the males are better at fighting off other males, or because females will choose to mate with the bigger or more decorated males. In either case, this variation in reproductive success generates a strong selection pressure among males to get those matings, resulting in the evolution of bigger body size and elaborate ornaments to get the females’ attention. Females, on the other hand, tend to get a handful of selected matings; therefore, they are more likely to select more desirable males.

Sexual dimorphism varies widely among species, of course, and some species are even sex-role reversed. In such cases, females tend to have a greater variance in their reproductive success than males and are correspondingly selected for the bigger body size and elaborate traits usually characteristic of males.

The selection pressures on males and females to obtain matings is known as sexual selection; it can result in the development of secondary sexual characteristics that do not benefit the individual’s likelihood of survival but help to maximize its reproductive success. Sexual selection can be so strong that it selects for traits that are actually detrimental to the individual’s survival. Think, once again, about the peacock’s tail. While it is beautiful and the male with the largest, most colorful tail is more likely to win the female, it is not the most practical appendage. In addition to being more visible to predators, it makes the males slower in their attempted escapes. There is some evidence that this risk, in fact, is why females like the big tails in the first place. The speculation is that large tails carry risk, and only the best males survive that risk: the bigger the tail, the more fit the male. This idea is known as the handicap principle.

The good genes hypothesis states that males develop these impressive ornaments to show off their efficient metabolism or their ability to fight disease. Females then choose males with the most impressive traits because it signals their genetic superiority, which they will then pass on to their offspring. Though it might be argued that females should not be picky because it will likely reduce their number of offspring, if better males father more fit offspring, it may be beneficial. Fewer, healthier offspring may increase the chances of survival more than many, weaker offspring.

Link to Learning

In 1915, biologist Ronald Fisher proposed another model of sexual selection: the Fisherian runaway model, which suggests that selection of certain traits is a result of sexual preference.

In both the handicap principle and the good genes hypothesis, the trait is said to be an honest signal of the males’ quality, thus giving females a way to find the fittest mates— males that will pass the best genes to their offspring.

No Perfect Organism

Natural selection is a driving force in evolution and can generate populations that are better adapted to survive and successfully reproduce in their environments. But natural selection cannot produce the perfect organism. Natural selection can only select on existing variation in the population; it does not create anything from scratch. Thus, it is limited by a population’s existing genetic variance and whatever new alleles arise through mutation and gene flow.

Natural selection is also limited because it works at the level of individuals, not alleles, and some alleles are linked due to their physical proximity in the genome, making them more likely to be passed on together (linkage disequilibrium). Any given individual may carry some beneficial alleles and some unfavorable alleles. It is the net effect of these alleles, or the organism’s fitness, upon which natural selection can act. As a result, good alleles can be lost if they are carried by individuals that also have several overwhelmingly bad alleles; likewise, bad alleles can be kept if they are carried by individuals that have enough good alleles to result in an overall fitness benefit.

Furthermore, natural selection can be constrained by the relationships between different polymorphisms. One morph may confer a higher fitness than another, but may not increase in frequency due to the fact that going from the less beneficial to the more beneficial trait would require going through a less beneficial phenotype. Think back to the mice that live at the beach. Some are light-colored and blend in with the sand, while others are dark and blend in with the patches of grass. The dark-colored mice may be, overall, more fit than the light-colored mice, and at first glance, one might expect the light-colored mice be selected for a darker coloration. But remember that the intermediate phenotype, a medium-colored coat, is very bad for the mice—they cannot blend in with either the sand or the grass and are more likely to be eaten by predators. As a result, the light-colored mice would not be selected for a dark coloration because those individuals that began moving in that direction (began being selected for a darker coat) would be less fit than those that stayed light.

Finally, it is important to understand that not all evolution is adaptive. While natural selection selects the fittest individuals and often results in a more fit population overall, other forces of evolution, including genetic drift and gene flow, often do the opposite: introducing deleterious alleles to the population’s gene pool. Evolution has no purpose—it is not changing a population into a preconceived ideal. It is simply the sum of the various forces described in this chapter and how they influence the genetic and phenotypic variance of a population.

Section Summary

Because natural selection acts to increase the frequency of beneficial alleles and traits while decreasing the frequency of deleterious qualities, it is adaptive evolution. Natural selection acts at the level of the individual, selecting for those that have a higher overall fitness compared to the rest of the population. If the fit phenotypes are those that are similar, natural selection will result in stabilizing selection, and an overall decrease in the population’s variation. Directional selection works to shift a population’s variance toward a new, fit phenotype, as environmental conditions change. In contrast, diversifying selection results in increased genetic variance by selecting for two or more distinct phenotypes.

Other types of selection include frequency-dependent selection, in which individuals with either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection) are selected for. Finally, sexual selection results from the fact that one sex has more variance in the reproductive success than the other. As a result, males and females experience different selective pressures, which can often lead to the evolution of phenotypic differences, or sexual dimorphisms, between the two.

Additional Self Check Questions

  1. In recent years, factories have become cleaner, and less soot is released into the environment. What impact do you think this has had on the distribution of moth color in the population?
  2. Give an example of a trait that may have evolved as a result of the handicap principle and explain your reasoning.
  3. List the ways in which evolution can affect population variation and describe how they influence allele frequencies.

Answers

  1. Moths have shifted to a lighter color.
  2. The peacock’s tail is a good example of the handicap principle. The tail, which makes the males more visible to predators and less able to escape, is clearly a disadvantage to the bird’s survival. But because it is a disadvantage, only the most fit males should be able to survive with it. Thus, the tail serves as an honest signal of quality to the females of the population; therefore, the male will earn more matings and greater reproductive success.
  3. There are several ways evolution can affect population variation: stabilizing selection, directional selection, diversifying selection, frequency-dependent selection, and sexual selection. As these influence the allele frequencies in a population, individuals can either become more or less related, and the phenotypes displayed can become more similar or more disparate.

Try It

adaptive evolution: increase in frequency of beneficial alleles and decrease in deleterious alleles due to selection

directional selection: selection that favors phenotypes at one end of the spectrum of existing variation

diversifying selection: selection that favors two or more distinct phenotypes

evolutionary fitness: (also, Darwinian fitness) individual’s ability to survive and reproduce

frequency-dependent selection: selection that favors phenotypes that are either common (positive frequency-dependent selection) or rare (negative frequency-dependent selection)

good genes hypothesis: theory of sexual selection that argues individuals develop impressive ornaments to show off their efficient metabolism or ability to fight disease

handicap principle: theory of sexual selection that argues only the fittest individuals can afford costly traits

honest signal: trait that gives a truthful impression of an individual’s fitness

relative fitness: individual’s ability to survive and reproduce relative to the rest of the population

sexual dimorphism: phenotypic difference between the males and females of a population

stabilizing selection: selection that favors average phenotypes


Adaptive Landscapes by Erik Svensson

Adaptive landscapes hold a central and special position in evolutionary theory, particularly in population and quantitative genetics, but also in some models of macroevolution. An adaptive landscape shows the relationship between fitness (vertical axis) and one or several traits or genes (horizontal axes). An adaptive landscape can therefore be viewed as a form of response surface, describing how a dependent variable (fitness) is causally influenced by one or several predictor variables (traits or genes). Evolution by natural selection in the context of an adaptive landscape can be viewed as a hill-climbing process, in which populations climb upwards to the trait or gene combination with the highest fitness, which are called “adaptive peaks.” In between the adaptive peaks, there are typically regions in phenotype or genotype space of low fitness (fitness valleys). Fitness valleys can also be thought of as the genetic combinations generating low-hybrid fitness when two incipient species meet and mate with each other, which generates a natural link between the adaptive landscape concept and speciation theory. In the original form and in the pre-computer era, adaptive landscapes were typically visualized as three-dimensional surface plots with only two traits (or genes). Adaptive landscapes did, in in their early days, mainly serve a heuristic function for qualitative reasoning, but over the last decades and with the development of evolutionary quantitative genetic theory and increasing computer power, they have now become a more quantitative tool for evolutionary biologists, including both theoreticians and empiricists. Whereas adaptive landscapes have become a part of mainstream evolutionary biology, they have also generated considerable controversy and confusion, as well as criticisms, mainly from philosophers. Some of these criticisms point to real conceptual problems, whereas others are based on misunderstandings of what the adaptive landscape actually is and what it can be used for.


Abstract

The notion that large body size confers some intrinsic advantage to biological species has been debated for centuries. Using a phylogenetic statistical approach that allows the rate of body size evolution to vary across a phylogeny, we find a long-term directional bias toward increasing size in the mammals. This pattern holds separately in 10 of 11 orders for which sufficient data are available and arises from a tendency for accelerated rates of evolution to produce increases, but not decreases, in size. On a branch-by-branch basis, increases in body size have been more than twice as likely as decreases, yielding what amounts to millions and millions of years of rapid and repeated increases in size away from the small ancestral mammal. These results are the first evidence, to our knowledge, from extant species that are compatible with Cope’s rule: the pattern of body size increase through time observed in the mammalian fossil record. We show that this pattern is unlikely to be explained by several nonadaptive mechanisms for increasing size and most likely represents repeated responses to new selective circumstances. By demonstrating that it is possible to uncover ancient evolutionary trends from a combination of a phylogeny and appropriate statistical models, we illustrate how data from extant species can complement paleontological accounts of evolutionary history, opening up new avenues of investigation for both.

The idea that large size confers some intrinsic advantage has lingered in the psyche of biologists for centuries. Researchers have proposed that bigger body sizes can increase tolerance to environmental extremes (1), reduce mortality (2), and enhance predation success (3), among other advantages. In support of these conjectures, analyses from a range of different taxonomic groups demonstrate that larger individuals within populations have significantly enhanced survival, fecundity, and mating success (4, 5). If these advantages are general and have played out over long time scales, they could explain the existence of Cope’s rule (6): a broad trend toward increasing size through time (4, 5, 7).

Mammals evolved from a relatively small common ancestor over 165 Ma (8 ⇓ –10) and went on to form one of the largest and most successful vertebrate radiations in Earth’s history. Mammals vary greatly in size, spanning almost eight orders of magnitude. This variation implies that some groups have experienced much greater evolutionary change in size from the ancestral form than others. Indeed, the mammalian fossil record provides the clearest evidence in support of Cope’s rule over long evolutionary time scales (6, 11, 12).

Despite the paleontological support, evidence for Cope’s rule remains elusive from studies of extant data alone (13 ⇓ –15), including studies of the mammals (16). A possible reason for the discrepancy between paleontological and extant data might be that conventional comparative methods for studying trends within extant data implicitly assume homogeneous evolutionary patterns and processes. When these assumptions are violated, it renders the homogeneous modeling approach incomplete at best and at worst, a source of potential bias in the study of historical evolutionary change for example, reconstructions of probable ancestral values can be biased toward average or intermediate values (17, 18), which would thereby mask long-term evolutionary trends that are apparent from the fossil record.

Previously, we have shown that rates of body size evolution in mammals routinely violate the assumption of homogeneity (19), but how these rate changes might be related to size itself has not been studied. If changes toward larger size in the mammals have consistently occurred at rates that differ from changes toward smaller size, then reconstructed ancestral states accounting for these rate differences may track more closely the observed fossil record. Such a pattern would allow the detection of size-related evolutionary trends from extant data (Fig. S1).

Here, we apply a statistical phylogenetic approach for reconstructing mammalian evolutionary history that allows the rate of evolution to vary throughout a phylogenetic tree without prior knowledge or specification of where and when rate shifts occurred. We use this method to test for size-related biases in rates of morphological change and ask whether accounting for any such bias allows us to predict a generalized pattern of size increase in the mammals in line with the generalized pattern of size increase observed in the fossil record. Finally, we consider whether a size-related bias in the rate of morphological evolution can help to choose among the several macroevolutionary processes that have been suggested to give rise to Cope’s rule.


Directional Selection

When the environment changes, populations will often undergo directional selection ([link]), which selects for phenotypes at one end of the spectrum of existing variation. A classic example of this type of selection is the evolution of the peppered moth in eighteenth- and nineteenth-century England. Prior to the Industrial Revolution, the moths were predominately light in color, which allowed them to blend in with the light-colored trees and lichens in their environment. But as soot began spewing from factories, the trees became darkened, and the light-colored moths became easier for predatory birds to spot. Over time, the frequency of the melanic form of the moth increased because they had a higher survival rate in habitats affected by air pollution because their darker coloration blended with the sooty trees. Similarly, the hypothetical mouse population may evolve to take on a different coloration if something were to cause the forest floor where they live to change color. The result of this type of selection is a shift in the population’s genetic variance toward the new, fit phenotype.


In science, sometimes things are believed to be true, and then new information comes to light that changes our understanding. The story of the peppered moth is an example: the facts behind the selection toward darker moths have recently been called into question. Read this article to learn more.


Non-conventional hosts – implications of ecological niches and genetic network architecture

Mesophilic organisms such as E. coli and S. cerevisiae have inherent properties that limit their use in certain applications, e.g. high temperature processes. Therefore, non-conventional microbial species play an important role in biotechnology [164–168].

Currently, limited data on the physiology of such organisms still represent a significant obstacle towards rational host cell engineering. Although there are many similarities in the biochemical networks across most microbial hosts, it is well documented that species and environmental niche-specific differences evolved. Whereas core sub-networks and pathways tend to be well conserved, the up- and downstream connections to other cellular networks vary significantly among different species and lead to species-specific differences of stress resistance in adverse environments [169, 170] (Figure 2). The evolutionary mechanisms described in the preceding sections are crucial towards the development of such specializations [130, 156, 171]. They allow anticipatory and foraging behavior in pro- and eukaryotic microbial cells [172–174]. In fact, a recent study in S. cerevisiae indicated that anticipatory gene regulatory patterns can evolve under cycling salt and oxidative stress conditions on a laboratory time scale within 300 generations and that cross-stress protection against salt and oxidative stress is strikingly asymmetrical, with oxidative stress protecting against salt stress but not vice versa[120]. Another recent study in E. coli showed that, by using increased genotypic diversity leveraged by a transposon library, evolutionarily ‘old’ anticipatory responses can be rapidly decoupled [172].

Species-specific differences in gene regulatory networks. Species-specific network properties allow for anticipatory behavior of the environment and consequently species-specific fitness trade-offs, in case that environmental stresses do not occur as in their natural order. Ultimately, these network properties may lead to distinct trade-offs among non-conventional host organisms during laboratory evolution.

Certain functions such as overflow metabolism in S. cerevisiae may have evolved in order to provide an evolutionary advantage in specific environments and to protect carbon resources from other competing species [175]. Consequently, there are differences in the regulatory blueprints of different species [169, 176, 177], which can ultimately lead to distinct evolutionary stress trade-offs during selection. Towards this end, a recent study with S. cerevisiae and Saccharomyces paradoxus showed that the evolutionary rescue (ER) frequency was positively correlated with stress concentration during 100 generations of evolution in S. cerevisiae but negatively correlated in S. paradoxus[44].

It can be concluded that insights into the adaptive cross-stress dependencies of one organism cannot infer the dependencies in a second organism with a distinct evolutionary background. As such, biotechnologists have to be aware that different (evolved) microbial hosts are likely to show distinct trade-offs during process-related stress exposure.


Acknowledgements

We are indebted to many people for providing images of specimens: James Clark, Roger Smith, Gert Wörheide, Oliver Rauhut, Neil Clark, Chris Brochu, Melanie Vovchuk, Juan Porfiri, Jeremías Taborda, Judith Babot, Hugo Carrizo, Diego Pol, Caitlin Syme, Rodolfo Salas-Gismondi, Lucy Souza, Jeremy Martin, Jessica Cundiff, Thomas Smith, Suresh Singh and the late Jon Tennant and Jaime Powell. We thank Eoin Gardiner for discussions about Cenozoic crocodylomorph evolution. Cranial silhouettes in the figures are by Haley O'Brien, Paul Gignac (used with permission) and T.L.S. jaw silhouettes are by T.L.S. Body silhouettes are modified from Stubbs et al. [22] and Ballell et al. [28], or artwork by Deverson da Silva, Nobu Tamura and Dmitry Bogdanov (available at http://phylopic.org/). This work was carried out using the computational facilities of the Advanced Computing Research Centre, University of Bristol - http://www.bris.ac.uk/acrc/.


Sexual Selection

Males and females of certain species are often quite different from one another in ways beyond the reproductive organs. Males are often larger, for example, and display many elaborate colors and adornments, like the peacock’s tail, while females tend to be smaller and duller in decoration. We call such differences sexual dimorphisms (Figure 5), which arise in many populations, particularly animal populations, where there is more variance in the male’s reproductive success than that of the females. That is, some males—often the bigger, stronger, or more decorated males—obtain the vast majority of the total matings, while others receive none. This can occur because the males are better at fighting off other males, or because females will choose to mate with the bigger or more decorated males. In either case, this variation in reproductive success generates a strong selection pressure among males to obtain those matings, resulting in the evolution of bigger body size and elaborate ornaments to attract the females’ attention. Females, however, tend to achieve a handful of selected matings therefore, they are more likely to select more desirable males.

Sexual dimorphism varies widely among species, and some species are even sex-role reversed. In such cases, females tend to have a greater variance in their reproductive success than males and are correspondingly selected for the bigger body size and elaborate traits usually characteristic of males.

Figure 5. Sexual dimorphism is observed in (a) peacocks and peahens, (b) Argiope appensa spiders (the female spider is the large one), and in (c) wood ducks. (credit “spiders”: modification of work by “Sanba38”/Wikimedia Commons credit “duck”: modification of work by Kevin Cole)

We call the selection pressures on males and females to obtain matings sexual selection. It can result in developing secondary sexual characteristics that do not benefit the individual’s likelihood of survival but help to maximize its reproductive success. Sexual selection can be so strong that it selects traits that are actually detrimental to the individual’s survival. Think, once again, about the peacock’s tail. While it is beautiful and the male with the largest, most colorful tail is more likely to win the female, it is not the most practical appendage. In addition to greater visibility to predators, it makes the males slower in their attempted escapes. There is some evidence that this risk is why females like the big tails in the first place. The speculation is that large tails carry risk, and only the best males survive that risk: the bigger the tail, the more fit the male. We call this the handicap principle .

The good genes hypothesis states that males develop these impressive ornaments to show off their efficient metabolism or their ability to fight disease. Females then choose males with the most impressive traits because it signals their genetic superiority, which they will then pass on to their offspring. Although one may argue that females should not be picky because it will likely reduce their number of offspring, if better males father more fit offspring, it may be beneficial. Fewer, healthier offspring may increase the chances of survival more than many, weaker offspring.

In both the handicap principle and the good genes hypothesis, the trait is an honest signal of the males’ quality, thus giving females a way to find the fittest mates— males that will pass the best genes to their offspring.


Many emerging invasive species display evidence of rapid adaptation. Contemporary genetic studies demonstrate that adaptation to novel environments can occur within 20 generations or less, indicating that evolutionary processes can influence invasiveness. However, the source of genetic or epigenetic variation underlying these changes remains uncharacterised. Here, we review the potential for rapid adaptation from standing genetic variation and from new mutations, and examine four types of evolutionary change that might promote or constrain rapid adaptation during the invasion process. Understanding the source of variation that contributes to adaptive evolution in invasive plants is important for predicting future invasion scenarios, identifying candidate genes involved in invasiveness, and, more generally, for understanding how populations can evolve rapidly in response to novel and changing environments.

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Author information

Affiliations

Quantitative Biology Center (QBiC), RIKEN, 6-2-3 Furuedai, Suita, Osaka, 565-0874, Japan

Takaaki Horinouchi, Shingo Suzuki & Chikara Furusawa

Department of Bioengineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan

Graduate School of Information Science and Technology, Osaka University, 1-5 Yamada-oka, Suita, Osaka, 565-0871, Japan

Takashi Hirasawa, Tetsuya Yomo, Hiroshi Shimizu & Chikara Furusawa

Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan

Graduate School of Frontier Biosciences, Osaka University, 1-5 Yamada-oka, Suita, Osaka, 565-0871, Japan


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