FN ISI Export Format VR 1.0 PT J AU Clabaut, C Salzburger, W Meyer, A TI Comparative phylogenetic analyses of the adaptive radiation of Lake Tanganyika cichlid fish: Nuclear sequences are less homoplasious but also less informative than mitochondrial DNA SO JOURNAL OF MOLECULAR EVOLUTION DE adaptive radiation; cichlid species flocks; explosive speciation; nuclear DNA phylogeny; NADH dehydrogenase subunit II; RAG1; C-lineage ID PROTEIN-CODING GENES; EXPLOSIVE SPECIATION; POPULATION-STRUCTURE; HAPLOCHROMINE FISH; ELEMENTS SINES; SPECIES FLOCK; EAST-AFRICA; EVOLUTION; VICTORIA; MALAWI AB Over 200 described endemic species make up the adaptive radiation of cichlids in Lake Tanganyika. This species assemblage has been viewed as both an evolutionary reservoir of old cichlid lineages and an evolutionary hotspot from which the modern cichlid lineages arose, seeding the adaptive radiations in Lakes Victoria and Malawi. Here we report on a phylogenetic analysis of Lake Tanganyika cichlids combining the previously determined sequences of the mitochondrial ND2 gene (1047 bp) with newly derived sequences of the nuclear RAG1 gene (similar to 700 bp of intron 2 and similar to 1100 bp of exon 3). The nuclear data-in agreement with mitochondrial DNA-suggest that Lake Tanganyika harbors several ancient lineages that did not undergo rampant speciation (e.g., Bathybatini, Trematocarini). We find strong support for the monophyly of the most species-rich Tanganyikan group, the Lamprologini, and we propose a new taxonomic group that we term the Clineage. The Haplochromini and Tropheini both have an 11-bp deletion in the intron of RAG1, strongly supporting the monophyly of this clade and its derived position. Mapping the phylogenetically informative positions revealed that, for certain branches, there are six times fewer apomorphies in RAG1. However, the consistency index of these positions is higher compared to the mitochondrial ND2 gene. Nuclear data therefore provide, on a per-base pair basis, less but more reliable phylogenetic information. Even if in our case RAG1 has not provided as much phylogenetic information as we expected, we suggest that this marker might be useful in the resolution of the phylogeny of older groups. PD NOV PY 2005 VL 61 IS 5 BP 666 EP 681 UT ISI:000232980100011 ER PT J AU Kozak, KH Larson, AA Bonett, RM Harmon, LJ TI Phylogenetic analysis of ecomorphological divergence, community structure, and diversification rates in dusky salamanders (Plethodontidae : Desmognathus) SO EVOLUTION DE adaptive radiation; Appalachian highlands; community ecology; comparative method; North America; phylogeography; speciation ID LIFE-HISTORY EVOLUTION; TESTING SPECIES BOUNDARIES; MITOCHONDRIAL-GENE TREES; ADAPTIVE RADIATION; BODY-SIZE; MOLECULAR PHYLOGENETICS; BEHAVIORAL INTERACTIONS; SOUTHERN APPALACHIANS; INFERRING PHYLOGENIES; MTDNA VARIATION AB An important dimension of adaptive radiation is the degree to which diversification rates fluctuate or remain constant through time. Focusing on plethodontid salamanders of the genus Desmognathus, we present a novel synthetic analysis of phylogeographic history, rates of ecomorphological evolution and species accumulation, and community assembly in an adaptive radiation. Dusky salamanders are highly variable in life history, body size, and ecology, with many endemic lineages in the southern Appalachian Highlands of eastern North America. Our results show that life-history evolution had important consequences for the buildup of plethodontid-salamander species richness and phenotypic disparity in eastern North America, a global hot spot of salamander biodiversity. The origin of Desmognathus species with aquatic larvae was followed by a high rate of lineage accumulation, which then gradually decreased toward the present time. The peak period of lineage accumulation in the group coincides with evolutionary partitioning of lineages with aquatic larvae into seepage, stream-edge, and stream microhabitats. Phylogenetic simulations demonstrate a strong correlation between morphology and microhabitat ecology independent of phylogenetic effects and suggest that ecomorphological changes are concentrated early in the radiation of Desmognathus. Deep phylogeoggraphic fragmentation within many codistributed ecomorph clades suggests long-term persistence of ecomorphological features and stability of endemic lineages and communities through multiple climatic cycles. Phylogenetic analyses of community structure show that ecomorph o logical divergence promotes the coexistence of lineages and that repeated, independent evolution of ruicrohabitat-associated ecomorphs has a limited role in the evolutionary assembly of Desniognathus communities. Comparing and contrasting our results to other adaptive radiations having different biogeographic histories, our results suggest that rates of diversification during adaptive radiation are intimately linked to the degree to which community structure persists over evolutionary time. PD SEP PY 2005 VL 59 IS 9 BP 2000 EP 2016 UT ISI:000232259300014 ER PT J AU Von Rintelen, T Glaubrecht, M TI Anatomy of an adaptive radiation: a unique reproductive strategy in the endemic freshwater gastropod Tylomelania (Cerithioidea : Pachychilidae) on Sulawesi, Indonesia and its biogeographical implications SO BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY DE molecular phylogeny; reproduction; species flock; systematics; viviparity; zoogeography ID AFRICAN CICHLID FISHES; LAKE TANGANYIKA; PHYLOGENETIC-RELATIONSHIPS; THALASSOID GASTROPODS; MOLECULAR PHYLOGENY; BAYESIAN-INFERENCE; DARWINS FINCHES; SPECIES FLOCK; ANCIENT LAKES; EAST-AFRICA AB The patterns of adaptive radiations in ancient lakes provide valuable clues to mechanisms of speciation and adaptation. In contrast to vertebrate radiations, for instance in fishes or finches, invertebrate species flocks have been largely neglected. While the increase in molecular data narrows this gap, the anatomical basis for interpreting these data against the background of evolutionary hypotheses is still widely lacking. Here we evaluate anatomical findings in the live-bearing pachychilid freshwater gastropod Tylomelania, which has radiated extensively in ancient lakes in the Indonesian island, Sulawesi; we have aimed at reconciling these data with recently obtained molecular phylogenetic evidence. Discovered more than a century ago, the speciose and phenotypically diverse species flock with 34 currently described taxa was only occasionally cited as an example of adaptive radiation in ancient lakes, while anatomical data were entirely lacking. Our study of anatomical characters reveals very low qualitative variation at the species level. Thus, contrary to earlier views we suggest the existence of a single monophyletic lineage endemic to this island. The most conspicuous feature of Tylomelania is its uterine brooding strategy, i.e. retaining eggs and embryos in the pallial oviduct. This is unique among South-East Asian pachychilids. Within the uterine brood pouch the offspring is surrounded by considerable amounts of nutritive material produced by a very large albumin gland, and the embryos are produced continuously. The shelled juveniles of some species are the largest known so far in viviparous gastropods, measuring almost 2 cm in length when hatching. This combination of reproductive features in Tylomelania, characterized by a high amount of maternal investment, is considered to be ovoviviparous, rendering its brooding strategy unique also among other gastropods. In addition, our data reject a previously assumed close relationship to other South-East Asian pachychilids and instead suggest the North Australian Pseudopotamis as sister group to Tylomelania. These findings have significant consequences for the phylogenetic interpretation of morphological characters of Tylomelania in an evolutionary and biogeographical context, leading to the hypothesis that the common ancestor of both genera originated somewhere on the northern Australian continental margin. (c) 2005 The Linnean Society of London. PD AUG PY 2005 VL 85 IS 4 BP 513 EP 542 UT ISI:000231057700010 ER PT J AU Howarth, DG Baum, DA TI Genealogical evidence of homoploid hybrid speciation in an adaptive radiation of Scaevola (goodeniaceae) in the Hawaiian Islands SO EVOLUTION DE adaptive radiation; Hawaiian Islands; homoploid; hybridization; nuclear introns; Scaevola; speciation ID POTENTIAL PHYLOGENETIC UTILITY; RBCL SPACER REGION; NITRATE REDUCTASE; CHARACTER EXPRESSION; SILVERSWORD ALLIANCE; GENETIC COMPOSITION; NATURAL HYBRIDS; WILD SUNFLOWERS; NUCLEAR GENE; EVOLUTION AB Although homoploid hybrid speciation is increasingly recognized as an important phenomenon in plant evolution, its role in adaptive radiations is poorly documented. We studied a clade of seven extant species of Scaevola that are endemic to the Hawaiian Islands and show substantial ecological and morphological diversity. We estimated the genealogies for alleles isolated from multiple accessions of each species at four nuclear loci: the ITS region, and the introns of three nuclear genes, LEAFY (LFY), NITRATE REDUCTASE (NIA), and GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE (G3PDH). For five of the seven species, there was complete concordance among the genealogies estimated from the four loci and, when all four regions were combined, the relationships among these five species were fully resolved. Inclusion of alleles from the remaining two species, S. procera and S. kilaueae, resulted in incongruence among loci, which appears to reflect a history of hybridization. Based on the distribution of alleles, we infer that S. procera is the result of a homoploid hybrid speciation event between S. gaudichaudii and S. mollis and that S. kilaueae is probably the result of hybrid speciation between S. coriacea and S. chamnissoniana. In each case the inferred hybridization is consistent with morphological, ecological, and geographic information. We conclude that homoploid hybrid speciation may be more common than is perceived and may play a role in generating novel combinations of adaptive traits that arise during island radiations. PD MAY PY 2005 VL 59 IS 5 BP 948 EP 961 UT ISI:000229456800003 ER PT J AU Joyce, DA Lunt, DH Bills, R Turner, GF Katongo, C Duftner, N Sturmbauer, C Seehausen, O TI An extant cichlid fish radiation emerged in an extinct Pleistocene lake SO NATURE ID VICTORIA; AFRICA; EVOLUTION; DESICCATION; ORIGIN; MODEL AB The haplochromine cichlid fish of the East African Great Lakes represent some of the fastest and most species-rich adaptive radiations known(1), but rivers in most of Africa accommodate only a few morphologically similar species of haplochromine cichlid fish. This has been explained by the wealth of ecological opportunity in large lakes compared with rivers. It is therefore surprising that the rivers of southern Africa harbour many, ecologically diverse haplochromines. Here we present genetic, morphological and biogeographical evidence suggesting that these riverine cichlids are products of a recent adaptive radiation in a large lake that dried up in the Holocene. Haplochromine species richness peaks steeply in an area for which geological data reveal the historical existence of Lake palaeo-Makgadikgadi(2,3). The centre of this extinct lake is now a saltpan north of the Kalahari Desert, but it once hosted a rapidly evolving fish species radiation, comparable in morphological diversity to that in the extant African Great Lakes. Importantly, this lake seeded all major river systems of southern Africa with ecologically diverse cichlids. This discovery reveals how local evolutionary processes operating during a short window of ecological opportunity can have a major and lasting effect on biodiversity on a continental scale. PD MAY 5 PY 2005 VL 435 IS 7038 BP 90 EP 95 UT ISI:000228864600044 ER PT J AU Salzburger, W Mack, T Verheyen, E Meyer, A TI Out of Tanganyika: Genesis, explosive speciation, key-innovations and phylogeography of the haplochromine cichlid fishes SO BMC EVOLUTIONARY BIOLOGY ID MITOCHONDRIAL-DNA SEQUENCES; AFRICAN RIFT SYSTEM; LAKE-TANGANYIKA; ADAPTIVE RADIATION; PHYLOGENETIC-RELATIONSHIPS; SYMPATRIC SPECIATION; POPULATION-STRUCTURE; MOLECULAR EVOLUTION; DIVERGENCE TIMES; SEXUAL SELECTION AB Background: The adaptive radiations of cichlid fishes in East Africa are well known for their spectacular diversity and their astonishingly fast rates of speciation. About 80% of all 2,500 cichlid species in East Africa, and virtually all cichlid species from Lakes Victoria (similar to 500 species) and Malawi (similar to 1,000 species) are haplochromines. Here, we present the most extensive phylogenetic and phylogeographic analysis so far that includes about 100 species and is based on about 2,000 bp of the mitochondrial DNA. Results: Our analyses revealed that all haplochromine lineages are ultimately derived from Lake Tanganyika endemics. We find that the three most ancestral lineages of the haplochromines sensu lato are relatively species poor, albeit widely distributed in Africa, whereas a fourth newly defined lineage - the 'modern haplochromines' - contains an unparalleled diversity that makes up more than 7% of the worlds' similar to 25,000 teleost species. The modern haplochromines' ancestor, most likely a riverine generalist, repeatedly gave rise to similar ecomorphs now found in several of the species flocks. Also, the Tanganyikan Tropheini are derived from that riverine ancestor suggesting that they successfully re-colonized Lake Tanganyika and speciated in parallel to an already established cichlid adaptive radiation. In contrast to most other known examples of adaptive radiations, these generalist ancestors were derived from highly diverse and specialized endemics from Lake Tanganyika. A reconstruction of life-history traits revealed that in an ancestral lineage leading to the modern haplochromines the characteristic egg-spots on anal fins of male individuals evolved. Conclusion: We conclude that Lake Tanganyika is the geographic and genetic cradle of all haplochromine lineages. In the ancestors of the replicate adaptive radiations of the 'modern haplochromines', behavioral (maternal mouthbrooding), morphological (egg-spots) and sexually selected (color polymorphism) key-innovations arose. These might be - together with the ecological opportunity that the habitat diversity of the large lakes provides - responsible for their evolutionary success and their propensity for explosive speciation. PD FEB 21 PY 2005 VL 5 AR 17 UT ISI:000227791200001 ER PT J AU Taylor, MS Hellberg, ME TI Marine radiations at small geographic scales: speciation in neotropical reef gobies (Elacatinus) SO EVOLUTION DE adaptive radiation; biogeography; Caribbean; phylogeny; reef fishes ID TROPICAL EASTERN PACIFIC; SEXUAL SELECTION; PHYLOGENETIC ANALYSIS; COMPARATIVE PHYLOGEOGRAPHY; GENETIC DIFFERENTIATION; POPULATION SUBDIVISION; 7-SPINED GOBIES; OCEAN CURRENTS; COMBINING DATA; FISH AB Studies of speciation in the marine environment have historically compared broad-scale distributions and estimated larval dispersal potential to infer the geographic barriers responsible for allopatric speciation. However, many marine clades show high species diversity in geographically restricted areas where barriers are not obvious and estimated dispersal potential should bring many sister taxa into contact. Genetic differentiation at small (separation < 1000 km) spatial scales could facilitate speciation by mechanisms other than the gradual accumulation of reproductive isolation during extended allopatry, such as ecological adaptation to local environmental conditions or the rapid evolution of genes tied to mate recognition, but the role of each of these possibilities has not been simultaneously explored for any species-rich marine taxon. Here, we develop a robust phylogenetic framework for 31 taxa from a species-rich group of Neotropical reef fishes (Gobiidae: Elacatinus) using 3230 bp from one mitochondrial and two nuclear gene regions. We use this framework to explore the contribution of large- and small-scale geographic isolation, ecological differentiation, and coloration toward the formation and maintenance of species. Although species of Elacatinus occur on both sides of the Isthmus of Panama, no sister species are separated by this barrier. Instead, our results indicate that sister taxa occur within oceans. Sister taxa usually differ by coloration, and more distantly related sympatric species frequently differ by resource use. This suggests that some combination of coloration and ecological differences may facilitate assortative mating at range boundaries or in sympatry. Overall, speciation in Elacatinus is consistent with a model of recurring adaptive radiations in stages taking place at small geographic scales. PD FEB PY 2005 VL 59 IS 2 BP 374 EP 385 UT ISI:000227468700011 ER PT J AU Valsecchi, E Pasolini, P Bertozzi, M Garoia, F Ungaro, N Vacchi, M Sabelli, B Tinti, F TI Rapid Miocene-Pliocene dispersal and evolution of Mediterranean rajid fauna as inferred by mitochondrial gene variation SO JOURNAL OF EVOLUTIONARY BIOLOGY DE 16S rDNA; control region; evolutionary history; palaeogeography; phylogeny; Rajidae ID THALASSOMA SPP. LABRIDAE; PHYLOGENETIC-RELATIONSHIPS; MOLECULAR PHYLOGENY; DNA; ATLANTIC; CHONDRICHTHYES; SHARKS; SKATES; PLEURONECTIFORMES; IDENTIFICATION AB Rajidae (colloquially known as skates and rays) experienced multiple and parallel adaptive radiations allowing high species diversity and great differences of species composition between regional faunas. Nevertheless, they show considerable conservation of bio-ecological, morphological and reproductive traits. The evolutionary history and dispersal of North-east Atlantic and Mediterranean rajid fauna were investigated throughout the sequence analysis of the control region and 16S rDNA mitochondrial genes. Molecular estimates of divergence times indicated recent origin and rapid dispersal of the present species. Compared with the ancient origin of the family (Late Cretaceous), the present species diversity arose in a relatively narrow time-window (12 Myr) from Middle Miocene to Early Pleistocene, likely by speciation processes related to dramatic geological and climatic events in the Mediterranean. Nucleotide substitution rates and phylogenetic relationships indicated Mediterranean endemic skates derived from sister species with wider distribution during Late Pliocene-Pleistocene. Skate phylogeny and systematics obtained using mitochondrial gene variation were largely consistent with those based on morpho-anatomical data. PD MAR PY 2005 VL 18 IS 2 BP 436 EP 446 UT ISI:000227017400019 ER PT J AU Glor, RE Gifford, ME Larson, A Losos, JB Schettino, LR Lara, ARC Jackman, TR TI Partial island submergence and speciation in an adaptive radiation: a multilocus analysis of the Cuban green anoles SO PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES DE adaptive radiation; speciation; introgression; hybridization; Anolis; Cuba ID MITOCHONDRIAL-GENE TREES; SYMPATRIC SPECIATION; PHYLOGENETIC-RELATIONSHIPS; MICROGEOGRAPHIC VARIATION; INFERRING PHYLOGENIES; POPULATION-STRUCTURE; DOMINICAN ANOLE; MTDNA VARIATION; CICHLID FISHES; HYBRID ZONE AB Sympatric speciation is often proposed to account for species-rich adaptive radiations within lakes or islands, where barriers to gene flow or dispersal may be lacking. However, allopatric speciation may also occur in such situations, especially when ranges are fragmented by fluctuating water levels. We test the hypothesis that Miocene fragmentation of Cuba into three palaeo-archipelagos accompanied species-level divergence in the adaptive radiation of West Indian Anolis lizards. Analysis of morphology, mitochondrial DNA (mt DNA) and nuclear DNA in the Cuban green anoles (carolinensis subgroup) strongly supports three predictions made by this hypothesis. First, three geographical sets of populations, whose ranges correspond with palaeo-archipelago boundaries, are distinct and warrant recognition as independent evolutionary lineages or species. Coalescence of nuclear sequence fragments sampled from these species and the large divergences observed between their mtDNA haplotypes suggest separation prior to the subsequent unification of Cuba ca. 5 Myr ago. Second, molecular phylogenetic relationships among these species reflect historical geographical relationships rather than morphological similarity. Third, all three species remain distinct despite extensive geographical contact subsequent to island unification, occasional hybridization and introgression of mtDNA haplotypes. Allopatric speciation initiated during partial island submergence may play an important role in speciation during the adaptive radiation of Anolis lizards. PD NOV 7 PY 2004 VL 271 IS 1554 BP 2257 EP 2265 UT ISI:000225107300008 ER PT J AU Schon, I Martens, K TI Adaptive, pre-adaptive and non-adaptive components of radiations in ancient lakes: a review SO ORGANISMS DIVERSITY & EVOLUTION DE ancient lakes; adaptive radiations; speciation; cichlids; ostracods; reproductive mode ID MITOCHONDRIAL-DNA SEQUENCES; AFRICAN CICHLID FISHES; EAST-AFRICA; SPECIES FLOCK; EXPLOSIVE SPECIATION; SEXUAL SELECTION; MALAWI CICHLIDS; GREAT-LAKES; PHYLOGENETIC-RELATIONSHIPS; PLEISTOCENE DESICCATION AB Ancient lakes are ideal model systems for evolutionary studies, as they hold hundreds of endemic species. The vast majority of these still occur in the cradle of their origin. We distinguish three different modes of speciation (allo-, para- and sympatric) which have occurred in these habitats. Although radiations from ancient lakes are generally assumed to be adaptive, we cannot fully support this point of view, because non-adaptive radiations also appear to be common, for example through chromosomal changes, hybridization or sexual selection. Even in supposedly adaptive cladogenesis, e.g. as concerns the presumed trophic adaptations of cichlid (Pisces) mouth and tooth shapes, both adaptive and non-adaptive components are acting. Distribution patterns of non-marine ostracods (Crustacea) within and outside of ancient lakes indicate that sexual reproduction might be an additional requirement for successful radiations in ancient lakes, at least in certain groups. This can best be understood by invoking ecology-based hypotheses on the evolutionary superiority of sexual reproduction such as Fisher-Muller accelerated evolution and the Tangled Bank. (C) 2004 Elsevier GmbH. All rights reserved. PY 2004 VL 4 IS 3 BP 137 EP 156 UT ISI:000224000400004 ER PT J AU Ackerly, DD Nyffeler, R TI Evolutionary diversification of continuous traits: phylogenetic tests and application to seed size in the California flora SO EVOLUTIONARY ECOLOGY DE adaptive radiation; angiosperms; California flora; comparative method; crown group; diversification; F-test; phylogeny; seed size; stem group ID INDEPENDENT CONTRASTS; CORRELATED EVOLUTION; PHENOTYPIC EVOLUTION; NICHE CONSERVATISM; LIFE-HISTORY; ADAPTATION; TREES; HYPOTHESES; CHARACTERS; PATTERNS AB Evolutionary diversification of a phenotypic trait reflects the tempo and mode of trait evolution, as well as the phylogenetic topology and branch lengths. Comparisons of trait variance between sister groups provide a powerful approach to test for differences in rates of diversification, controlling for differences in clade age. We used simulation analyses under constant rate Brownian motion to develop phylogenetically based F-tests of the ratio of trait variances between sister groups. Random phylogenies were used for a generalized evolutionary null model, so that detailed internal phylogenies are not required, and both gradual and speciational models of evolution were considered. In general, phylogenetically structured tests were more conservative than corresponding parametric statistics (i.e., larger variance ratios are required to achieve significance). The only exception was for comparisons under a speciational evolutionary model when the group with higher variance has very low sample size ( number of species). The methods were applied to a large data set on seed size for 1976 species of California flowering plants. Seven of 37 sister-group comparisons were significant for the phylogenetically structured tests ( compared to 12 of 37 for the parametric F-test). Groups with higher diversification of seed size generally had a greater diversity of fruit types, life form, or life history as well. The F-test for trait variances provides a simple, phylogenetically structured approach to test for differences in rates of phenotypic diversification and could also provide a valuable tool in the study of adaptive radiations. PD MAY PY 2004 VL 18 IS 3 BP 249 EP 272 UT ISI:000222678900004 ER PT J AU Salzburger, W Meyer, A TI The species flocks of East African cichlid fishes: recent advances in molecular phylogenetics and population genetics SO NATURWISSENSCHAFTEN ID INTERSPERSED REPETITIVE ELEMENTS; LATE PLEISTOCENE DESICCATION; MITOCHONDRIAL-DNA SEQUENCES; LAKE LEVEL FLUCTUATIONS; SYMPATRIC SPECIATION; SEXUAL SELECTION; CICHLASOMA-CITRINELLUM; EXPLOSIVE SPECIATION; ADAPTIVE RADIATION; RAPID EVOLUTION AB With more than 3,000 species, the fish family Cichlidae is one of the most species-rich families of vertebrates. Cichlids occur in southern and central America, Africa, Madagascar, and India. The hotspot of their biodiversity is East Africa, where they form adaptive radiations composed of hundreds of endemic species in several lakes of various sizes and ages. The unparalleled species richness of East African cichlids has been something of a conundrum for evolutionary biologists and ecologists, since it has been in doubt whether these hundreds of species arose by allopatric speciation or whether it is necessary to invoke somewhat less traditional models of speciation, such as micro-allopatric, peripatric, or even sympatric speciation or evolution through sexual selection mediated by female choice. Ernst Mayr's analyses of these evolutionary uniquely diverse species assemblages have contributed to a more direct approach to this problem and have led to a deeper understanding of the patterns and processes that caused the formation of these huge groups of species. We review here recent molecular data on population differentiation and phylogenetics, which have helped to unravel, to some extent, the patterns and processes that led to the formation and ecological maintenance of cichlid species flocks. It is becoming apparent that sexually selected traits do play an important role in speciation in micro-allopatric or even sympatric settings. Species richness seems to be roughly correlated with the surface area, but not the age, of the lakes. We observe that the oldest lineages of a species flock of cichlids are often less species-rich and live in the open water or deepwater habitats. While the species flocks of the Lake Malawai and the Lake Victoria areas were shown to be monophyletic, the cichlid assemblage of Lake Tanganyika seems to consist of several independent species flocks. Cichlids emerge as an evolutionary model system in which many fundamental questions in evolution and ecology can be tested successfully, yet for other fish species flocks the relative importance of alternative mechanisms of speciation is likely to differ from that in cichlid fish. PD JUN PY 2004 VL 91 IS 6 BP 277 EP 290 UT ISI:000222514100003 ER PT J AU Seehausen, O TI Hybridization and adaptive radiation SO TRENDS IN ECOLOGY & EVOLUTION ID SILVERSWORD ALLIANCE ASTERACEAE; MITOCHONDRIAL-DNA PHYLOGENIES; VICTORIA CICHLID FISHES; LAKE VICTORIA; INTROGRESSIVE HYBRIDIZATION; SYMPATRIC SPECIATION; HYBRID SPECIATION; SPECIES FLOCK; SALVELINUS-FONTINALIS; GENETIC-VARIATION AB Whether interspecific hybridization is important as a mechanism that generates biological diversity is a matter of controversy. Whereas some authors focus on the potential of hybridization as a source of genetic variation, functional novelty and new species, others argue against any important role, because reduced fitness would typically render hybrids an evolutionary dead end. By drawing on recent developments in the genetics and ecology of hybridization and on principles of ecological speciation theory, I develop a concept that reconciles these views and adds a new twist to this debate. Because hybridization is common when populations invade new environments and potentially elevates rates of response to selection, it predisposes colonizing populations to rapid adaptive diversification under disruptive or divergent selection. I discuss predictions and suggest tests of this hybrid swarm theory of adaptive radiation and review published molecular phylogenies of adaptive radiations in light of the theory. PD APR PY 2004 VL 19 IS 4 BP 198 EP 207 UT ISI:000220842400007 ER PT J AU Gamble, C Davies, W Pettitt, P Richards, M TI Climate change and evolving human diversity in Europe during the last glacial SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES DE radiation; stage 3; late glacial; Greenland ice-core project; radiocarbon; phylogeography ID HOMINID EVOLUTION; GREENLAND ICE; SETTLEMENT; SPECIATION; RECORD; MTDNA; VARIABILITY; REGION; IBERIA; AGCM AB A link between climate change and human evolution during the Pleistocene has often been assumed but rarely tested. At the macro-evolutionary level Foley showed for hominids that extinction, rather than speciation, correlates with environmental change as recorded in the deep sea record. Our aim is to examine this finding at a smaller scale and with high-resolution environmental and archaeological archives. Our interest is in changing patterns of human dispersal under shifting Pleistocene climates during the last glacial period in Europe. Selecting this time frame and region allows us to observe how two hominid taxa, Neanderthals and Cro-Magnons, adapted to climatic conditions during oxygen isotope stage 3. These taxa are representative of two hominid adaptive radiations, termed terrestrial and aquatic, which exhibited different habitat preferences but similar tolerances to climatic factors. Their response to changing ecological conditions was predicated upon their ability to extend their societies in space and time. We examine this difference further using a database of all available radiocarbon determinations from western Europe in the late glacial. These data act as proxies for population history, and in particular the expansion and contraction of regional populations as climate changed rapidly. Independent assessment of these processes is obtained from the genetic history of Europeans. The results indicate that climate affects population contraction rather than expansion. We discuss the consequences for genetic and cultural diversity which led to the legacy of the Ice Age: a single hominid species, globally distributed. PD FEB 29 PY 2004 VL 359 IS 1442 BP 243 EP 253 UT ISI:000189180100014 ER PT J AU Kelly, C Price, TD TI Comparative methods based on species mean values SO MATHEMATICAL BIOSCIENCES DE comparative methods; errors in variables; linear regression; random effects; fixed effects; hypothesis testing; maximum-likelihood estimation ID CORRELATED EVOLUTION; INDEPENDENT CONTRASTS; ADAPTIVE RADIATIONS; ALLOMETRY; SIZE; ADAPTATION; SELECTION; WARBLERS; HISTORY; MAMMALS AB Comparative methods that use simple linear regression based on species mean values introduce three difficulties with respect to the standard regression model. First, species values may not be independent because they form part of a hierarchically structured phylogeny. Second, variation about the regression line includes two sources of error: 'biological error' due to deviations of the true species mean values from the regression line and sampling error associated with the estimation of these mean values [B. Riska, Am. Natural. 138 (1991) 283]. Third, sampling error in the independent variable results in an attenuated estimate of the regression slope. We consider estimation and hypothesis testing using two statistical models which explicitly justify the use of the species mean values, without the need to account for phylogenetic relationships. The first (random-effects) is based on an evolutionary model whereby species evolve to fill a bivariate normal niche space, and the second (fixed-effects) is concerned with describing a relationship among the particular species included in a study, where the only source of error is in the estimation of species mean values. We use a modification of the maximum-likelihood method to obtain an unbiased estimate of the regression slope. For three real datasets we find a close correspondence between this slope and that obtained by simply regressing the species mean values on each other. In the random effects model, the P-value also approximates that based on the regression of species mean values. In the fixed effects model, the P-value is typically much lower. Simulated examples illustrate that the maximum-likelihood approach is useful when the accuracy in estimating the species mean values is low, but the traditional method based on a regression of the species mean values may often be justified provided that the evolutionary model can be justified. (C) 2004 Elsevier Inc. All rights reserved. PD FEB PY 2004 VL 187 IS 2 BP 135 EP 154 UT ISI:000188839400002 ER PT J AU Patterson, TB Givnish, TJ TI Geographic cohesion, chromosomal evolution, parallel adaptive radiations, and consequent floral adaptations in Calochortus (Calochortaceae): evidence from a cpDNA phylogeny SO NEW PHYTOLOGIST DE adaptive radiation; California Floristic Province; Calochortus; convergence; consequent radiation; floral syndromes; geographic cohesion; parallel evolution ID CHLOROPLAST DNA; METAL TOLERANCE; SEQUENCE DATA; THLASPI-CAERULESCENS; POLLINATION SYSTEMS; MOLECULAR EVOLUTION; MIMULUS-GUTTATUS; COPPER TOLERANCE; SOUTHERN AFRICA; DIVERSIFICATION AB We developed a molecular phylogeny for Calochortus (Liliaceae) to reconstruct historical patterns of evolution. Three cpDNA segments were sequenced and analyzed using parsimony. We identified seven major, geographically cohesive clades centered mainly in the California Floristic Province. Section Calochortus is monophyletic; section Mariposa, paraphyletic; and section Cyclobothra, polyphyletic. Calochortus arose in the Coast Ranges, which were uplifited 3-5 million yr ago. Three of the four major floral syndromes evolved at least twice, associated with particular environments. Serpentine tolerance evolved at least seven times. We argue that limited dispersal led to the narrow endemism of individual species, the geographic cohesion of clades, and parallel radiations in habitat preference, floral morphology, and serpentine tolerance. Chromosomal evolution allowed Calochortus to 'double-up' its regional radiations, preventing crosses between pairs of clades with overlapping ranges. Floral evolution in Calochortus is an example of consequent radiation, with selection for local diversification in habitat driving secondary specialization of flowers on the range of pollinators and abiotic conditions within each habitat, rather than selection to partition pollinators within habitats driving adaptive radiation. PD JAN PY 2004 VL 161 IS 1 BP 253 EP 264 UT ISI:000187417700029 ER PT J AU MacLean, RC Bell, G TI Divergent evolution during an experimental adaptive radiation SO PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES DE Pseudomonas; Biolog; selection experiment; adaptive radiation; contingency; correlated response ID TERM EXPERIMENTAL EVOLUTION; ESCHERICHIA-COLI; UNIFORM SELECTION; SACCHAROMYCES-CEREVISIAE; EXPERIMENTAL POPULATIONS; CORRELATED RESPONSES; GENETIC-DIVERGENCE; FITNESS; ADAPTATION; POLYMORPHISM AB 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. PD AUG 7 PY 2003 VL 270 IS 1524 BP 1645 EP 1650 UT ISI:000184689100015 ER PT J AU Benkman, CW TI Divergent selection drives the adaptive radiation of crossbills SO EVOLUTION DE ecological theory of adaptive radiation; feeding performance; fitness surface; Loxia curvirostra; morphological evolution; natural selection; stabilizing selection ID FOOD PROFITABILITY; FORAGING BEHAVIOR; EVOLUTION; COEVOLUTION; PATTERNS; FITNESS; ECOLOGY AB Knowledge of how phenotype influences fitness is necessary if we are to understand the basis of natural selection and how natural selection contributes to adaptive radiations. Here I quantify selection on a wild population of red crossbills (Loxia curvirostra complex) in the South Hills, Idaho. Bill depth is the target of selection and selection on bill depth is stabilizing. I then show how fitness is related to both bill depth and performance. I use these and previously published relationships to estimate a fitness surface for five species of red crossbills that are part of an ongoing adaptive radiation in western North America. The fitness surface for crossbills has distinct peaks and valleys, with each crossbill species residing on or very near the summits. This work strongly supports a key tenet of the ecological theory of adaptive radiations; namely, divergent selection for utilizing alternative resources is the ultimate cause of adaptive radiations. PD MAY PY 2003 VL 57 IS 5 BP 1176 EP 1181 UT ISI:000183500900021 ER PT J AU Ernst, A Becker, S Wollenzien, UIA Postius, C TI Ecosystem-dependent adaptive radiations of picocyanobacteria inferred from 16S rRNA and ITS-1 sequence analysis SO MICROBIOLOGY-SGM ID SP STRAIN BO-8402; RIBOSOMAL-RNA; TRANSCRIBED SPACER; LAKE CONSTANCE; PHYLOGENETIC-RELATIONSHIPS; SYNECHOCOCCUS STRAINS; GENETIC DIVERSITY; 16S-RIBOSOMAL RNA; CYANOBACTERIA; PICOPLANKTON AB Small, coccoid and rod-shaped Synechococcus-type cyanobacteria with either phycoerythrin or phycocyanin as major accessory pigments were isolated from several large, temperate-zone lakes and the brackish Baltic Sea. The picocyanobacteria had two ribosomal operons with a long internal transcribed spacer (ITS-1) separating the 16S rDNA and 23S rDNA. A 16S rRNA-based phylogenetic analysis assigned all isolates to the picophytoplankton clade [sensu Urbach, E., Scanlan, D. J., Distel, D. L., Waterbury, J. B. & Chisholm, S. W. (11998). J Mol Evol 46, 188-201], which also comprises marine Synechococcus spp. and Prochlorococcus spp. The strains assorted to five paraphyletic clusters each containing two or more strains with 99(.)4-100% 16S rRNA sequence identity. Five corresponding strain clusters were deduced from analysis of ITS-1 sequences. Sequence divergence in ITS-1 varied between 23% in the most divergent and 1% in the phylogenetically most conserved cluster. Clustered strains with low sequence divergence in ITS-1 were frequently isolated from a single ecosystem or hydrographically comparable lakes in the same region. They represent physiologically distinct ecotypes of species which, among other phenotypic variations, frequently differed in their major accessory pigments, the phycobiliproteins. The reproduction of the various pigment traits in different lineages was not correlated with the phylogenetic divergence deduced from 16S rRNA or ITS-1 sequences but rather seemed to be related to characteristics of the ecosystem and habitat from which the strains were isolated. The occurrence of a comparable spectrum of phenotypes in different lineages and ecosystems indicates that different strain clusters developed similar ecotypes during independent adaptive radiations. PD JAN PY 2003 VL 149 PN Part 1 BP 217 EP 228 UT ISI:000180536500022 ER PT J AU Losos, JB Miles, DB TI Testing the hypothesis that a clade has adaptively radiated: Iguanid lizard clades as a case study SO AMERICAN NATURALIST DE adaptive radiation; disparity; iguanid; lizard ID MORPHOLOGICAL DIVERSITY; ANOLIS LIZARDS; DIVERSIFICATION RATES; EVOLUTION; DISPARITY; PERFORMANCE; DAMSELFLIES; TROPIDURUS; STRATEGIES; PATTERNS AB The study of adaptive radiations has played a fundamental role in understanding mechanisms of evolution. A recent resurgence in the study of adaptive radiations highlights a gap in our knowledge about determining whether a clade constitutes adaptive diversification. Specifically, no objective criteria exist to judge whether a clade constitutes an adaptive radiation. Most clades, given enough time, will diversify adaptively to some extent; therefore, we argue that the term "adaptive radiation" should be reserved for those clades that are exceptionally diverse in terms of the range of habitats occupied and attendant morphological adaptations. Making such a definition operational, however, requires a comparative analysis of many clades. Only by comparing clades can one distinguish those that are exceptionally diverse (or nondiverse) from those exhibiting a normal degree of adaptive disparity. We propose such a test, focusing on disparity in the ecological morphology of monophyletic groups within the lizard family Iguanidae. We find that two clades, the Polychrotinae and Phrynosomatinae, are exceptionally diverse and that two others, the Crotaphytinae and Oplurinae, are exceptionally nondiverse. Potential explanations for differences in diversity are discussed, as are caveats and future extensions of our approach. PD AUG PY 2002 VL 160 IS 2 BP 147 EP 157 UT ISI:000176977900001 ER PT J AU Harvey, PH Rambaut, A TI Comparative analyses for adaptive radiations SO PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES DE comparative method; evolution; adaptation; ecological niche ID PHYLOGENETICALLY INDEPENDENT CONTRASTS; CORRELATED EVOLUTION; PHYLOGENIES AB Biologists generally agree that most morphological variation between closely related species is adaptive. The most common method of comparative analysis to test for co-evolved character variation is based on a Brownian-motion model of character evolution. If we are to test for the evolution of character covariation, and we believe that characters have evolved adaptively to fill niches during an adaptive radiation, then it is appropriate to employ appropriate models for character evolution. We show here that under several models of adaptive character evolution and coevolution during an adaptive radiation, which result in closely related species being more similar to each other than to more distantly related species, cross-species analyses are statistically more appropriate than contrast analyses. If the evolution of some traits fits the Brownian-motion model, while others evolve to fill niches during an adaptive radiation, it might be necessary to identify the number of relevant niche dimensions and the modes of character evolution before deciding on appropriate statistical procedures. Alternatively, maximum-likelihood procedures might be used to determine appropriate transformations of phylogenetic branch lengths that accord with particular models of character evolution. PD NOV 29 PY 2000 VL 355 IS 1403 BP 1599 EP 1605 UT ISI:000166088400007 ER PT J AU Svensson, E Hedenstrom, A TI A phylogenetic analysis of the evolution of moult strategies in Western Palearctic warblers (Aves : Sylviidae) SO BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY DE adaptation; biannual moult; birds; breeding; character maintenance; comparative study; migration; split-moult ID WORLD LEAF WARBLERS; GENUS PHYLLOSCOPUS; CORRELATED EVOLUTION; ADAPTIVE RADIATIONS; WILLOW WARBLERS; WING-MOLT; TRADE-OFF; REPRODUCTION; BIRDS; ADAPTATION AB Adult birds replace their flight feathers (moult) at least once per year, either in summer after termination of breeding or (in the case of some long-distance migratory species) in the winter quarters. We reconstructed the evolutionary pathways leading to summer and winter moult using recently published molecular phylogenetic information on the relationships of the Western Palearctic warblers (Aves: Sylviidae). Our phylogenetic analysis indicates that summer moult is the ancestral pattern and that winter moult has evolved 7-10 times in this clade. As taxa increased their migratory distance and colonized northern breeding areas, summer moult disappeared and winter moult evolved. Our data also allows us to trace the historical origins of unusual moult patterns such as the split-moult and biannual moult strategies: the most parsimonous explanations for their origins is that they evolved from ancestral states of summer moult. We briefly discuss our results in the light of recent criticisms against phylogenetic comparative methods and the utility of historical versus functional definitions of adapation. (C) 1999 The Linnean Society of London. PD JUN PY 1999 VL 67 IS 2 BP 263 EP 276 UT ISI:000080912500007 ER PT J AU Losos, JB Jackman, TR Larson, A de Queiroz, K Rodriguez-Schettino, L TI Contingency and determinism in replicated adaptive radiations of island lizards SO SCIENCE ID ANOLIS LIZARDS; EVOLUTION AB The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes. PD MAR 27 PY 1998 VL 279 IS 5359 BP 2115 EP 2118 UT ISI:000072775600050 ER PT J AU HAYDON, DT CROTHER, BI PIANKA, ER TI NEW DIRECTIONS IN BIOGEOGRAPHY SO TRENDS IN ECOLOGY & EVOLUTION AB The deduction of biogeographic process from the study of its history is complicated by the fact that history is a singular thing. This singularity allows no estimation of the degree of determinism surrounding the realization of biogeographic processes, and consequently we know almost nothing about the generality of such deductions. Here we discuss a new approach, called 'experimental biogeography', that exploits computers to model faunal build-up repeatedly against a fixed vicariant background over ecological and evolutionary time scales. This new approach enables a biogeographer to be omniscient - to know both vicariant history and actual phylogeny. Moreover, history can be replayed repeatedly to accumulate a sample of multiple phylogenies and to estimate probability density functions for biogeographic variables. Roles of stochastic, historical and ecological processes in adaptive radiations can also be assessed. Experimental biogeography allows examination of the reliability of various methods of recovering historical patterns. PD OCT PY 1994 VL 9 IS 10 BP 403 EP 406 UT ISI:A1994PE12200021 ER PT J AU BROOKS, DR MCLENNAN, DA TI COMPARATIVE-STUDY OF ADAPTIVE RADIATIONS WITH AN EXAMPLE USING PARASITIC FLATWORMS (PLATYHELMINTHES, CERCOMERIA) SO AMERICAN NATURALIST ID PHYLOGENETIC ANALYSIS; GENETIC REVOLUTIONS; RANDOM CLADES; EVOLUTION; DIVERSIFICATION; MORPHOLOGY; SPECIATION; TESTS; CERCOMEROMORPHA; CYCLOPHYLLIDEA AB Studies of adaptive radiations require robust phylogenies, estimates of species numbers for monophyletic groups within clades, assessments of the adaptive value of putative key innovations, and estimates of the frequency of speciation modes. Four criteria are necessary to identify an adaptive radiation within the parasitic platyhelminths: (1) a group contains significantly more species than its sister group, (2) species richness is apomorphic, (3) apomorphic traits enhance the potential for adaptively driven modes of speciation (sympatric speciation and speciation by peripheral isolation via host switching), and (4) the frequency of adaptively driven speciation modes is high within the group when compared with data from free-living groups. Only the species-rich Monogenea fulfill all four criteria. The Digenea and Eucestoda also are more species rich than their sister groups, their species richness is derived, and they possess unique characters that increase the potential for host switching to occur. However, because there is not enough information to determine whether the frequency of adaptive modes of speciation is high for those groups, we cannot yet assert that their radiations have been adaptive. PD NOV PY 1993 VL 142 IS 5 BP 755 EP 778 UT ISI:A1993ML22600002 ER EF