Adaptive Radiation

14,000,000 Leading Edge Experts on the ideXlab platform

Scan Science and Technology

Contact Leading Edge Experts & Companies

Scan Science and Technology

Contact Leading Edge Experts & Companies

The Experts below are selected from a list of 24303 Experts worldwide ranked by ideXlab platform

Jonathan B. Losos - One of the best experts on this subject based on the ideXlab platform.

  • Ecological Opportunity and Adaptive Radiation
    Annual Review of Ecology Evolution and Systematics, 2016
    Co-Authors: James T. Stroud, Jonathan B. Losos
    Abstract:

    The process of Adaptive Radiation—the proliferation of species from a single ancestor and diversification into many ecologically different forms—has been of great interest to evolutionary biologists since Darwin. Since the middle of the last century, ecological opportunity has been invoked as a potential key to understanding when and how Adaptive Radiation occurs. Interest in the topic of ecological opportunity has accelerated as research on Adaptive Radiation has experienced a resurgence, fueled in part by advances in phylogenetic approaches to studying evolutionary diversification. Nonetheless, what the term actually means, much less how it mechanistically leads to Adaptive diversification, is currently debated; whether the term has any predictive value or is a heuristic useful only for post hoc explanation also remains unclear. Recent recognition that evolutionary change can occur rapidly and on a timescale commensurate with ecological processes suggests that it is time to synthesize ecological and evo...

  • Adaptive Radiation, Ecological Opportunity, and Evolutionary Determinism
    The American Naturalist, 2010
    Co-Authors: Jonathan B. Losos
    Abstract:

    Abstract: Adaptive Radiation refers to diversification from an ancestral species that produces descendants adapted to use a great variety of distinct ecological niches. In this review, I examine two aspects of Adaptive Radiation: first, that it results from ecological opportunity and, second, that it is deterministic in terms of its outcome and evolutionary trajectory. Ecological opportunity is usually a prerequisite for Adaptive Radiation, although in some cases, Radiation can occur in the absence of preexisting opportunity. Nonetheless, many clades fail to radiate although seemingly in the presence of ecological opportunity; until methods are developed to identify and quantify ecological opportunity, the concept will have little predictive utility in understanding a priori when a clade might be expected to radiate. Although predicted by theory, replicated Adaptive Radiations occur only rarely, usually in closely related and poorly dispersing taxa found in the same region on islands or in lakes. Continge...

  • lizards in an evolutionary tree ecology and Adaptive Radiation of anoles
    2009
    Co-Authors: Jonathan B. Losos
    Abstract:

    Adaptive Radiation, which results when a single ancestral species gives rise to many descendants, each adapted to a different part of the environment, is possibly the single most important source of biological diversity in the living world. One of the best-studied examples involves Caribbean Anolis lizards. With about 400 species, Anolis has played an important role in the development of ecological theory and has become a model system exemplifying the integration of ecological, evolutionary, and behavioral studies to understand evolutionary diversification. This major work, written by one of the best-known investigators of Anolis, reviews and synthesizes an immense literature. Jonathan B. Losos illustrates how different scientific approaches to the questions of adaptation and diversification can be integrated and examines evolutionary and ecological questions of interest to a broad range of biologists.

  • Adaptive Radiation: contrasting theory with data.
    Science, 2009
    Co-Authors: Sergey Gavrilets, Jonathan B. Losos
    Abstract:

    Biologists have long been fascinated by the exceptionally high diversity displayed by some evolutionary groups. Adaptive Radiation in such clades is not only spectacular, but is also an extremely complex process influenced by a variety of ecological, genetic, and developmental factors and strongly dependent on historical contingencies. Using modeling approaches, we identify 10 general patterns concerning the temporal, spatial, and genetic/morphological properties of Adaptive Radiation. Some of these are strongly supported by empirical work, whereas for others, empirical support is more tentative. In almost all cases, more data are needed. Future progress in our understanding of Adaptive Radiation will be most successful if theoretical and empirical approaches are integrated, as has happened in other areas of evolutionary biology.

  • testing the island effect in Adaptive Radiation rates and patterns of morphological diversification in caribbean and mainland anolis lizards
    Proceedings of The Royal Society B: Biological Sciences, 2008
    Co-Authors: Gabriel Silva Pinto, Luke J. Harmon, Luke D Mahler, Jonathan B. Losos
    Abstract:

    Many of the classic examples of Adaptive Radiation, including Caribbean Anolis lizards, are found on islands. However, Anolis also exhibits substantial species richness and ecomorphological disparity on mainland Central and South America. We compared patterns and rates of morphological evolution to investigate whether, in fact, island Anolis are exceptionally diverse relative to their mainland counterparts. Quite the contrary, we found that rates and extent of diversification were comparable—Anolis Adaptive Radiation is not an island phenomenon. However, mainland and Caribbean anoles occupy different parts of morphological space; in independent colonizations of both island and mainland habitats, island anoles have evolved shorter limbs and better-developed toe pads. These patterns suggest that the two areas are on different evolutionary trajectories. The ecological causes of these differences are unknown, but may relate to differences in predation or competition among mainland and island communities.

Dolph Schluter - One of the best experts on this subject based on the ideXlab platform.

  • ecological character displacement in Adaptive Radiation
    The American Naturalist, 2000
    Co-Authors: Dolph Schluter
    Abstract:

    abstract: I give an overview of the observational and experimental evidence for ecological character displacement in Adaptive Radiation. Sixty‐one published cases of character displacement involving closely related species (congeners) make up the observational data set. All cases involve divergence, even though parallel and convergent displacement are theoretically possible. Character ratios in sympatry were greatest when displacement was symmetric (mean 1.54) and least when asymmetric (mean 1.29), perhaps because the most symmetric resource distributions are also the broadest. Carnivores are vastly overrepresented in the data compared with other trophic groups, with herbivores the next most common category. I consider five hypotheses to explain this pattern, including the possibility that the likelihood of divergence via competition depends on position in food webs. Overall, the quality and completeness of observational data has improved in recent years, as judged by the extent to which individual cases ...

  • Introduction to the Symposium: Species Interactions and Adaptive Radiation
    The American Naturalist, 2000
    Co-Authors: Dolph Schluter
    Abstract:

    The purpose of this supplement is to explore the effects of interactions between species on the evolution of diversity, with an emphasis on lineages undergoing Adaptive Radiation. By “Adaptive Radiation,” I mean the relatively rapid proliferation of new species from a single ancestor accompanied by expansion to new resources and environments and by divergence in phenotypic traits used to exploit those environments. The process may have many causes, but here we focus on the role of interactions between members of the diversifying lineage. Adaptive Radiation is a good place to center an inquiry into the evolutionary consequences of species interactions because so much of ecological diversity, perhaps even most of it, has arisen by Adaptive Radiation. Species interactions, especially competition, have also been regarded as important causes of phenotypic differentiation in Adaptive Radiation. Finally, interactions play an important role in several ecological theories of speciation, especially sympatric speciation.

  • the ecology of Adaptive Radiation
    2000
    Co-Authors: Dolph Schluter
    Abstract:

    1. The origins of ecological diversity 2. Detecting Adaptive Radiation 3. The progress of Adaptive Radiation 4. The ecological theory of Adaptive Radiation 5. Divergent natural selection between environments 6. Divergence and species interactions 7. Ecological opportunity speciation 8. The ecological basis of speciation 9. Divergence along genetic lines of least resistance 10. The ecology of Adaptive Radiation

  • ecological causes of Adaptive Radiation
    The American Naturalist, 1996
    Co-Authors: Dolph Schluter
    Abstract:

    According to the naturalists of the first half of this century, Adaptive Radiation is the outcome of three ecological processes: phenotypic differentiation of populations by resource-based divergent natural selection, phenotypic differentiation through resource competition (ecological opportunity and divergent character displacement), and ecological speciation (speciation as a consequence of adaptation to different resource environments). Despite a recent surge of interest in the phenomenon, especially in phylogenetic histories of Radiations, we know too little about the ecology of most Radiations to assess the roles of the three processes. I summarize our own efforts to test the theory with a Radiation of three-spined sticklebacks apparently still in its early stages. The role of divergent selection is supported by a strong relationship among populations and species in mean morphology, feeding performance, habitat use, and growth rate. Trade-offs in feeding performance and growth rate between habitats ar...

  • experimental evidence that competition promotes divergence in Adaptive Radiation
    Science, 1994
    Co-Authors: Dolph Schluter
    Abstract:

    Interspecific competition driving divergence in Adaptive Radiation has not previously been tested experimentally. Natural selection on a morphologically variable species of stickleback fish was contrasted in the presence and absence of a close relative. Selection was nondirectional when the target species was alone, whereas addition of the second species favored individuals most different from it morphologically and ecologically. Disproportionately severe competition between similar phenotypes indicates frequency-dependent selection, verifying a crucial element of theory of competition and character divergence. The findings help resolve outstanding debates on the ecological causes of diversification and the evolutionary consequences of competitive interactions.

Ole Seehausen - One of the best experts on this subject based on the ideXlab platform.

  • The coincidence of ecological opportunity with hybridization explains rapid Adaptive Radiation in Lake Mweru cichlid fishes
    Nature Communications, 2019
    Co-Authors: Joana I. Meier, Catherine E. Wagner, Rike B. Stelkens, Domino A. Joyce, Salome Mwaiko, Numel Phiri, Ulrich K. Schliewen, Oliver Selz, Cyprian Katongo, Ole Seehausen
    Abstract:

    The process of Adaptive Radiation was classically hypothesized to require isolation of a lineage from its source (no gene flow) and from related species (no competition). Alternatively, hybridization between species may generate genetic variation that facilitates Adaptive Radiation. Here we study haplochromine cichlid assemblages in two African Great Lakes to test these hypotheses. Greater biotic isolation (fewer lineages) predicts fewer constraints by competition and hence more ecological opportunity in Lake Bangweulu, whereas opportunity for hybridization predicts increased genetic potential in Lake Mweru. In Lake Bangweulu, we find no evidence for hybridization but also no Adaptive Radiation. We show that the Bangweulu lineages also colonized Lake Mweru, where they hybridized with Congolese lineages and then underwent multiple Adaptive Radiations that are strikingly complementary in ecology and morphology. Our data suggest that the presence of several related lineages does not necessarily prevent Adaptive Radiation, although it constrains the trajectories of morphological diversification. It might instead facilitate Adaptive Radiation when hybridization generates genetic variation, without which Radiation may start much later, progress more slowly or never occur. Recent studies have suggested that hybridization can facilitate Adaptive Radiations. Here, the authors show that opportunity for hybridization differentiates Lake Mweru, where cichlids radiated, and Lake Bangweulu, where cichlids did not radiate despite ecological opportunity in both lakes.

  • A Combinatorial View on Speciation and Adaptive Radiation
    Trends in Ecology and Evolution, 2019
    Co-Authors: David Alexander Marques, Joana I. Meier, Ole Seehausen
    Abstract:

    Speciation is often thought of as a slow process due to the waiting times for mutations that cause incompatibilities, and permit ecological differentiation or assortative mating. Cases of rapid speciation and particularly cases of rapid Adaptive Radiation into multiple sympatric species have remained somewhat mysterious. We review recent findings from speciation genomics that reveal an emerging commonality among such cases: reassembly of old genetic variation into new combinations facilitating rapid speciation and Adaptive Radiation. The polymorphisms in old variants frequently originated from hybridization at some point in the past. We discuss why old variants are particularly good fuel for rapid speciation, and hypothesize that variation in access to such old variants might contribute to the large variation in speciation rates observed in nature.

  • Upward Adaptive Radiation Cascades: Predator Diversification Induced by Prey Diversification
    Trends in Ecology and Evolution, 2017
    Co-Authors: Jakob Brodersen, David M. Post, Ole Seehausen
    Abstract:

    The value of biodiversity is widely appreciated, but we are only beginning to understand the interplay of processes that generate biodiversity and their consequences for coevolutionary interactions. Whereas predator–prey coevolution is most often analyzed in the context of evolutionary arms races, much less has been written about how predators are affected by, and respond to, evolutionary diversification in their prey. We hypothesize here that Adaptive Radiation of prey may lead to diversification and potentially speciation in predators, a process that we call an upwards Adaptive Radiation cascade. In this paper we lay out the conceptual basis for upwards Adaptive Radiation cascades, explore evidence for such cascades, and finally advocate for intensified research.

  • Ecological opportunity and sexual selection together predict Adaptive Radiation
    Nature, 2012
    Co-Authors: Catherine E. Wagner, Luke J. Harmon, Ole Seehausen
    Abstract:

    Adaptive Radiation of cichlid fishes in the African Great Lakes is predictable, but only when species traits and environmental factors are jointly considered. African cichlid fish provide a classic example of Adaptive Radiation, the rapid diversification of a lineage into a separate species adapted to exploit a new habitat or resource. Cichlids have evolved in this way in about 30 known cases, but, even for them, Adaptive Radiation is not the norm and there are more than one hundred instances in which it has not occurred. This study compares 656 cichlid species in 46 lakes in a search for factors that might govern whether Radiation occurs. Adaptive Radiation is found to be more likely in deeper, older and sunnier lakes, and where species show high levels of sexual selection. A fundamental challenge to our understanding of biodiversity is to explain why some groups of species undergo Adaptive Radiations, diversifying extensively into many and varied species, whereas others do not1,2. Both extrinsic environmental factors (for example, resource availability, climate) and intrinsic lineage-specific traits (for example, behavioural or morphological traits, genetic architecture) influence diversification, but few studies have addressed how such factors interact. Radiations of cichlid fishes in the African Great Lakes provide some of the most dramatic cases of species diversification. However, most cichlid lineages in African lakes have not undergone Adaptive Radiations. Here we compile data on cichlid colonization and diversification in 46 African lakes, along with lake environmental features and information about the traits of colonizing cichlid lineages, to investigate why Adaptive Radiation does and does not occur. We find that extrinsic environmental factors related to ecological opportunity and intrinsic lineage-specific traits related to sexual selection both strongly influence whether cichlids radiate. Cichlids are more likely to radiate in deep lakes, in regions with more incident solar Radiation and in lakes where there has been more time for diversification. Weak or negative associations between diversification and lake surface area indicate that cichlid speciation is not constrained by area, in contrast to diversification in many terrestrial taxa3. Among the suite of intrinsic traits that we investigate, sexual dichromatism, a surrogate for the intensity of sexual selection, is consistently positively associated with diversification. Thus, for cichlids, it is the coincidence between ecological opportunity and sexual selection that best predicts whether Adaptive Radiation will occur. These findings suggest that Adaptive Radiation is predictable, but only when species traits and environmental factors are jointly considered.

  • African cichlid fish: a model system in Adaptive Radiation research
    Proceedings of The Royal Society B: Biological Sciences, 2006
    Co-Authors: Ole Seehausen
    Abstract:

    The African cichlid fish Radiations are the most diverse extant animal Radiations and provide a unique system to test predictions of speciation and Adaptive Radiation theory. The past few years have seen major advances in the phylogenetics, evolutionary biogeography and ecology of cichlid fish. Most of this work has concentrated on the most diverse Radiations. Unfortunately, a large number of small Radiations and 'non-Radiations' have been overlooked, potentially limiting the contribution of the cichlid system to our understanding of speciation and Adaptive Radiation. I have reviewed the literature to identify 33 intralacustrine Radiations and 76 failed Radiations. For as many as possible I collected information on lake size, age and phylogenetic relationships. I use these data to address two questions: (i) whether the rate of speciation and the resulting species richness are related to temporal and spatial variation in ecological opportunity and (ii) whether the likelihood of undergoing Adaptive Radiation is similar for different African cichlid lineages. The former is a key prediction of the ecological theory of Adaptive Radiation that has been presumed true but remains untested for cichlid Radiations. The second is based on the hypothesis that the propensity of cichlids to radiate is due to a key evolutionary innovation shared by all African cichlids. The evidence suggests that speciation rate declines through time as niches get filled up during Adaptive Radiation: young Radiations and early stages of old Radiations are characterized by high rates of speciation, whereas at least 0.5 Myr into a Radiation speciation becomes a lot less frequent. The number of species in cichlid Radiations increases with lake size, supporting the prediction that species diversity increases with habitat heterogeneity, but also with opportunity for isolation by distance. Finally, the data suggest that the propensity to radiate within lakes is a derived property that evolved during the evolutionary history of some African cichlids, and the appearance of which does not coincide with the appearance of proposed key innovations in morphology and life history.

R. Craig Maclean - One of the best experts on this subject based on the ideXlab platform.

  • Adaptive Radiation in microbial microcosms.
    Journal of Evolutionary Biology, 2005
    Co-Authors: R. Craig Maclean
    Abstract:

    It has often been argued that evolutionary diversification is the result of divergent natural selection for specialization on alternative resources. I provide a comprehensive review of experiments that examine the ecology and genetics of resource specialization and Adaptive Radiation in microbial microcosms. In these experiments, resource heterogeneity generates divergent selection for specialization on alternative resources. At a molecular level, the evolution of specialization is generally attributable to mutations that de-regulate the expression of existing biosynthetic and catabolic pathways. Trade-offs are associated with the evolution of resource specialization, but these trade-offs are often not the result of antagonistic pleiotropy. Replicate Adaptive Radiations result in the evolution of a similar assemblage of specialists, but the genetic basis of specialization differs in replicate Radiations. The implications of microbial selection experiments for evolutionary theory are discussed and future directions of research are proposed.

  • Resource competition and Adaptive Radiation in a microbial microcosm
    Ecology Letters, 2004
    Co-Authors: R. Craig Maclean, Alison Dickson, Graham Bell
    Abstract:

    Theory predicts that competition for shared resources in a monomorphic population generates divergent selection for adaptation to alternative resources. Experimental tests of this hypothesis are scarce. We selected populations of the bacterium Pseudomonas fluorescens in spatially homogeneous microcosms containing a complex mixture of resources. Initially, all populations consisted of two isogenic clones. The outcome of selection was the evolution of a diverse community of genotypes within each population. Sympatric genotypes exhibited differentiation in metabolic traits related to resource acquisition and frequency-dependent trade-offs in competitive ability, as we would expect if different genotypes consumed different resources. These results are consistent with the hypothesis of Adaptive Radiation driven by resource competition. Reconciling the results of this study with those of earlier experiments provides a new interpretation of the ecological causes of Adaptive Radiation in microbial microcosms.

  • Divergent evolution during an experimental Adaptive Radiation.
    Proceedings of The Royal Society B: Biological Sciences, 2003
    Co-Authors: R. Craig Maclean, Graham Bell
    Abstract:

    How repeatable a process is evolution? Comparative studies of multicellular eukaryotes and experimental studies with unicellular prokaryotes document the repeated evolution of Adaptive phenotypes during similar Adaptive Radiations, suggesting that the outcome of Adaptive Radiation is broadly reproducible. The goal of this study was to test this hypothesis by using phenotypic traits to infer the genetic basis of adaptation to simple carbon-limited environments in an extensive Adaptive Radiation. We used a clone of the bacterium Pseudomonas fluorescens to found two sets of experimental lines. The first set of lines was allowed to adapt to one of 23 novel environments for 1100 generations while the second set of lines was allowed to accumulate mutations by drift for 2000 generations. All lines were then assayed in the 95 environments provided by Biolog microplates to determine the phenotypic consequences of selection and drift. Replicate selection lines propagated in a common environment evolved similar Adaptive components of their phenotype but showed extensive variation in non-Adaptive phenotypic traits. This variation in non-Adaptive phenotypic traits primarily resulted from the ascendance of different beneficial mutations in different lines. We argue that these results reconcile experimental and comparative approaches to studying adaptation by demonstrating that the convergent phenotypic evolution that occurs during Adaptive Radiation may be associated with radically different sets of beneficial mutations.

  • Experimental Adaptive Radiation in Pseudomonas.
    The American Naturalist, 2002
    Co-Authors: R. Craig Maclean, Graham Bell
    Abstract:

    Abstract: We studied the importance of selection and constraint in determining the limits of Adaptive Radiation and the consequences of Adaptive Radiation in an experimental system. We propagated four replicate lines of the bacterium Pseudomonas fluorescens derived from a single ancestral clone in 95 environments, where growth was limited by the availability of a single carbon source for 1,000 generations. We then assayed the growth of the ancestral clone and the evolved lines in all 95 environments. Evolved lines increased their performance in almost every selection environment and invaded 70% of the novel environments as a direct response to selection. Direct responses tended to be larger in environments where growth was initially poor. Although evolved lines lost the ability to grow on about three substrates that their ancestor could readily grow on, the correlated response to selection was, on average, positive. The correlated response allowed all of our evolved populations to expand their niches and ...

Graham Bell - One of the best experts on this subject based on the ideXlab platform.

  • Resource competition and Adaptive Radiation in a microbial microcosm
    Ecology Letters, 2004
    Co-Authors: R. Craig Maclean, Alison Dickson, Graham Bell
    Abstract:

    Theory predicts that competition for shared resources in a monomorphic population generates divergent selection for adaptation to alternative resources. Experimental tests of this hypothesis are scarce. We selected populations of the bacterium Pseudomonas fluorescens in spatially homogeneous microcosms containing a complex mixture of resources. Initially, all populations consisted of two isogenic clones. The outcome of selection was the evolution of a diverse community of genotypes within each population. Sympatric genotypes exhibited differentiation in metabolic traits related to resource acquisition and frequency-dependent trade-offs in competitive ability, as we would expect if different genotypes consumed different resources. These results are consistent with the hypothesis of Adaptive Radiation driven by resource competition. Reconciling the results of this study with those of earlier experiments provides a new interpretation of the ecological causes of Adaptive Radiation in microbial microcosms.

  • Divergent evolution during an experimental Adaptive Radiation.
    Proceedings of The Royal Society B: Biological Sciences, 2003
    Co-Authors: R. Craig Maclean, Graham Bell
    Abstract:

    How repeatable a process is evolution? Comparative studies of multicellular eukaryotes and experimental studies with unicellular prokaryotes document the repeated evolution of Adaptive phenotypes during similar Adaptive Radiations, suggesting that the outcome of Adaptive Radiation is broadly reproducible. The goal of this study was to test this hypothesis by using phenotypic traits to infer the genetic basis of adaptation to simple carbon-limited environments in an extensive Adaptive Radiation. We used a clone of the bacterium Pseudomonas fluorescens to found two sets of experimental lines. The first set of lines was allowed to adapt to one of 23 novel environments for 1100 generations while the second set of lines was allowed to accumulate mutations by drift for 2000 generations. All lines were then assayed in the 95 environments provided by Biolog microplates to determine the phenotypic consequences of selection and drift. Replicate selection lines propagated in a common environment evolved similar Adaptive components of their phenotype but showed extensive variation in non-Adaptive phenotypic traits. This variation in non-Adaptive phenotypic traits primarily resulted from the ascendance of different beneficial mutations in different lines. We argue that these results reconcile experimental and comparative approaches to studying adaptation by demonstrating that the convergent phenotypic evolution that occurs during Adaptive Radiation may be associated with radically different sets of beneficial mutations.

  • Experimental Adaptive Radiation in Pseudomonas.
    The American Naturalist, 2002
    Co-Authors: R. Craig Maclean, Graham Bell
    Abstract:

    Abstract: We studied the importance of selection and constraint in determining the limits of Adaptive Radiation and the consequences of Adaptive Radiation in an experimental system. We propagated four replicate lines of the bacterium Pseudomonas fluorescens derived from a single ancestral clone in 95 environments, where growth was limited by the availability of a single carbon source for 1,000 generations. We then assayed the growth of the ancestral clone and the evolved lines in all 95 environments. Evolved lines increased their performance in almost every selection environment and invaded 70% of the novel environments as a direct response to selection. Direct responses tended to be larger in environments where growth was initially poor. Although evolved lines lost the ability to grow on about three substrates that their ancestor could readily grow on, the correlated response to selection was, on average, positive. The correlated response allowed all of our evolved populations to expand their niches and ...