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Results for “convergent evolution”

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PubMed2006

Genetic evidence for the convergent evolution of light skin in Europeans and East Asians.

Human skin pigmentation shows a strong positive correlation with ultraviolet radiation intensity, suggesting that variation in skin color is, at least partially, due to adaptation via natural selection. We investigated the evolution of pigmentation variation by testing for the presence of positive directional selection in 6 pigmentation genes using an empirical F(ST) approach, through an examination of global diversity patterns of these genes in the Centre d'Etude du Polymorphisme Humain (CEPH)-Diversity Panel, and by exploring signatures of selection in data from the International HapMap project. Additionally, we demonstrated a role for MATP in determining normal skin pigmentation variation using admixture mapping methods. Taken together (with the results of previous admixture mapping studies), these results point to the importance of several genes in shaping the pigmentation phenotype and a complex evolutionary history involving strong selection. Polymorphisms in 2 genes, ASIP and OCA2, may play a shared role in shaping light and dark pigmentation across the globe, whereas SLC24A5, MATP, and TYR have a predominant role in the evolution of light skin in Europeans but not in East Asians. These findings support a case for the recent convergent evolution of a lighter pigmentation phenotype in Europeans and East Asians.

Black or African American↗

PubMed1994

Convergent evolution: the need to be explicit.

Convergence as a phenomenon in molecular evolution is an issue that confuses many discussions. Often the problem is that not enough care is taken to state exactly what kind of convergence one has in mind. Functional and mechanistic convergence are both common, and some structural convergence has probably occurred, but a convincing case for genuine sequence convergence has yet to be made.

Amino Acid Sequence↗

PubMed1997

Convergent evolution of apolipoprotein(a) in primates and hedgehog.

Apolipoprotein(a) [apo(a)] is the distinguishing protein component of lipoprotein(a), a major inherited risk factor for atherosclerosis. Human apo(a) is homologous to plasminogen. It contains from 15 to 50 repeated domains closely related to plasminogen kringle four, plus single kringle five-like and inactive protease-like domains. This expressed gene is confined to a subset of primates. Although most mammals lack apo(a), hedgehogs produce an apo(a)-like protein composed of highly repeated copies of a plasminogen kringle three-like domain, with complete absence of protease domain sequences. Both human and hedgehog apo(a)-like proteins form covalently linked lipoprotein particles that can bind to fibrin and other substrates shared with plasminogen. DNA sequence comparisons and phylogenetic analysis indicate that the human type of apo(a) evolved from a duplicated plasminogen gene during recent primate evolution. In contrast, the kringle three-based type of apo(a) evolved from an independent duplication of the plasminogen gene approximately 80 million years ago. In a type of convergent evolution, the plasminogen gene has been independently remodeled twice during mammalian evolution to produce similar forms of apo(a) in two widely divergent groups of species.

Animals↗

PubMed1997

Evidence for convergent evolution of A and B blood group antigens in primates.

To determine whether convergent or trans-specific evolution is responsible for the persistence of the ABO polymorphism in apes, we have sequenced segments of introns 5 and 6 of the ABO gene. Four substitutions and one insertion or deletion group human A, B, and O alleles together, separate from their chimpanzee A and gorilla B counterparts. No shared substitutions support a trans-species mode of evolution for any of the alleles examined. We conclude that the A and B antigens of the chimpanzee and gorilla, respectively, have arisen by convergent evolution. Phylogenetic analysis suggests that the human A and B alleles are ancient, having diverged at least 3 million years ago. These alleles must have therefore been trans-specifically inherited within the genus Homo.

ABO Blood-Group System↗

PubMed2005

Convergent evolution: floral guides, stingless bee nest entrances, and insectivorous pitchers.

Several recent hypotheses, including sensory drive and sensory exploitation, suggest that receiver biases may drive selection of biological signals in the context of sexual selection. Here we suggest that a similar mechanism may have led to convergence of patterns in flowers, stingless bee nest entrances, and pitchers of insectivorous plants. A survey of these non-related visual stimuli shows that they share features such as stripes, dark centre, and peripheral dots. Next, we experimentally show that in stingless bees the close-up approach to a flower is guided by dark centre preference. Moreover, in the approach towards their nest entrance, they have a spontaneous preference for entrance patterns containing a dark centre and disrupted ornamentation. Together with existing empirical evidence on the honeybee's and other insects' orientation to flowers, this suggests that the signal receivers of the natural patterns we examined, mainly Hymenoptera, have spontaneous preferences for radiating stripes, dark centres, and peripheral dots. These receiver biases may have evolved in other behavioural contexts in the ancestors of Hymenoptera, but our findings suggest that they have triggered the convergent evolution of visual stimuli in floral guides, stingless bee nest entrances, and insectivorous pitchers.

Animals↗

PubMed2004

Evidence for widespread convergent evolution around human microsatellites.

Microsatellites are a major component of the human genome, and their evolution has been much studied. However, the evolution of microsatellite flanking sequences has received less attention, with reports of both high and low mutation rates and of a tendency for microsatellites to cluster. From the human genome we generated a database of many thousands of (AC)(n) flanking sequences within which we searched for common characteristics. Sequences flanking microsatellites of similar length show remarkable levels of convergent evolution, indicating shared mutational biases. These biases extend 25-50 bases either side of the microsatellite and may therefore affect more than 30% of the entire genome. To explore the extent and absolute strength of these effects, we quantified the observed convergence. We also compared homologous human and chimpanzee loci to look for evidence of changes in mutation rate around microsatellites. Most models of DNA sequence evolution assume that mutations are independent and occur randomly. Allowances may be made for sites mutating at different rates and for general mutation biases such as the faster rate of transitions over transversions. Our analysis suggests that these models may be inadequate, in that proximity to even very short microsatellites may alter the rate and distribution of mutations that occur. The elevated local mutation rate combined with sequence convergence, both of which we find evidence for, also provide a possible resolution for the apparently contradictory inferences of mutation rates in microsatellite flanking sequences.

Base Sequence↗

PubMed2002

Interaction with simian Hck tyrosine kinase reveals convergent evolution of the Nef protein from simian and human immunodeficiency viruses despite differential molecular surface usage.

Simian and human immunodeficiency virus type 1 (SIV and HIV-1) Nef proteins are thought to use different molecular surfaces to mediate the protein-protein interactions required for their otherwise similar functions. This genetically separable function suggests convergent evolution of primate lentiviruses and/or structural differences between human and nonhuman primate cellular target proteins. However, such comparative molecular analyses have not been undertaken so far using the respective natural host-derived cellular targets. We cloned simian Src family kinase Hck and analyzed structurally and biochemically its interaction with SIV Nef.

Amino Acid Sequence↗

PubMedDate not supplied

Queuosine modification of tRNA: a case for convergent evolution.

Queuosine is a hypermodified nucleoside found in position 34, the anticodon wobble position, of four tRNA species. This modification is distributed with near uniformity across all life forms found on this planet. Yet the molecular mechanisms involved with accomplishing this ubiquitous posttranscriptional modification of tRNA are dramatically different between prokaryotic and eukaryotic organisms, which suggests that these were formed by convergent evolution of a fundamental life process essential to nearly all life forms. This minireview describes the differences between these modification systems and points to a new direction for developing research on the molecular function queuosine-modified tRNA in diverse species.

Animals↗

PubMed1987

The complex Arom locus of Aspergillus nidulans. Evidence for multiple gene fusions and convergent evolution.

The physical positions of the DNA sequences encoding the five consecutive enzyme activities required to metabolise 3-deoxy-D-arabino-heptulosonic acid-7-phosphate to 5-enolpyruvyl-shikimate-3phosphate, which are encoded by the A. nidulans Arom polypeptide have been determined. Subfragments of the Arom locus encoding EPSP synthase and 3-dehydroquinase have been expressed in appropriate E. coli aro mutants. The DNA sequence of the A. nidulans Arom locus has been shown to have homology with the corresponding unlinked E. coli aro loci strongly suggesting (I) divergent evolution from common ancestral sequences and (II) that the complex A. nidulans Arom locus arose by multiple gene fusion. The DNA and protein sequence of the two 3-dehydroquinase isoenzymes of A. nidulans share no homology, strongly indicating separate phylogenetic origins and their convergent evolution. The 5' and 3' non-translated DNA sequence of the A. nidulans Arom locus is presented along with the presumed sites for transcription initiation and polyadenylation determined by S1 nuclease protection experiments.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗

PubMed1997

Old World fruitbat phylogeny: evidence for convergent evolution and an endemic African clade.

Knud Andersen (1912, Catalogue of the Chiroptera in the Collections of the British Museum: I. Megachiroptera, British Museum of Natural History, London) divided Old World fruitbats (family Pteropodidae) into the rousettine, cynopterine, epomophorine, eonycterine, and notopterine sections. The latter two sections comprise the subfamily Macroglossinae; members of this subfamily exhibit specializations for nectarivory (e.g., elongated, protrusible, brushy tongues) and cluster together in cladistic analyses based on anatomical characters. Other evidence, including single-copy DNA hybridization, suggests that macroglossines are either paraphyletic or polyphyletic; this implies that adaptations for pollen and nectar feeding evolved independently in different macroglossine lineages or were lost in nonmacroglossines after evolving in a more basal common ancestor. Hybridization data also contradict Andersen's phylogeny in providing support for an endemic African clade that includes representatives of three of Andersen's sections. Here, we present complete mitochondrial 12S rRNA and valine tRNA gene sequences for 20 pteropodids, including representatives of all of Andersen's sections, and examine the aforementioned controversies. Maximum likelihood, minimum evolution, and maximum parsimony analyses all contradict macroglossine monophyly and provide support for an African clade that associates Megaloglossus and Lissonycteris and those two with Epomophorus. In conjunction with the DNA hybridization results, there are now independent lines of molecular evidence suggesting: (i) convergent evolution of specializations for nectarivory, at least in Megaloglossus versus other macroglossines, and (ii) a previously unrecognized clade of endemic Africa taxa. Estimates of divergence time based on 12S rRNA and DNA hybridization data are also in good agreement and suggest that extant fruitbats trace back to a common ancestor 25 million to 36 million years ago.

Africa↗

PubMed2001

Convergent evolution of MutS and topoisomerase II for clamping DNA crossovers and stacked Holliday junctions.

This study shows that topoisomerase II and MutS proteins share a structural motif that has, in its dimeric form, a suitable geometry for clamping the two arms of either right-handed DNA crossovers or their isostructural stacked Holliday junctions. This defines a new protein family selected by convergent evolution for sensing DNA topology and binding recombination intermediates. This study also proposes that MutS binding on 2-fold right-handed crossover provides a mechanism for strand discrimination during DNA translocation.

Adenosine Triphosphatases↗

PubMed2005

Convergent evolution and divergent selection: lizards at the White Sands ecotone.

Ecological transition zones, where organismal phenotypes result from a delicate balance between selection and migration, highlight the interplay of local adaptation and gene flow. Here, I study the response of an entire species assemblage to natural selection across a common ecotone. Three lizard species, distributed along a dramatic environmental gradient in substrate color, display convergent adaptation of blanched coloration on the gypsum dunes of White Sands National Monument. I investigate the role of gene flow in modulating phenotypic response to selection by quantifying color variation and genetic variation across the ecotone. I find species differences in degree of background matching and in genetic connectivity of populations across the ecotone. Differences among species in phenotypic response to selection scale precisely to levels of genetic isolation. Species with higher levels of gene flow across the ecotone exhibit less dramatic responses to selection. Results also reveal a strong signal of ecologically mediated divergence for White Sands lizards. For all species, phenotypic variation is better explained by habitat similarity than genetic similarity. Convergent evolution of blanched coloration at White Sands clearly reflects the action of strong divergent selection; however, adaptive response appears to be modulated by gene flow and demographic history and can be predicted by divergence-with-gene-flow models.

Animals↗

PubMed1997

Structure of Haemophilus influenzae Fe(+3)-binding protein reveals convergent evolution within a superfamily.

The first crystal structure of the iron-transporter ferric ion-binding protein from Haemophilus influenzae (hFBP), at 1.6 A resolution, reveals the structural basis for iron uptake and transport required by several important bacterial pathogens. Paradoxically, although hFBP belongs to a protein superfamily which includes human transferrin, iron binding in hFBP and transferrin appears to have developed independently by convergent evolution. Structural comparison of hFBP with other prokaryotic periplasmic transport proteins and the eukaryotic transferrins suggests that these proteins are related by divergent evolution from an anion-binding common ancestor, not from an iron-binding ancestor. The iron binding site of hFBP incorporates a water and an exogenous phosphate ion as iron ligands and exhibits nearly ideal octahedral metal coordination. FBP is highly conserved, required for virulence, and is a nodal point for free iron uptake in several Gram-negative pathogenic bacteria, thus providing a potential target for broad-spectrum antibacterial drug design against human pathogens such as H. influenzae, Neisseria gonorrhoeae, and Neisseria meningitidis.

Amino Acid Sequence↗

PubMed2005

Convergent evolution of chemical defense in poison frogs and arthropod prey between Madagascar and the Neotropics.

With few exceptions, aposematically colored poison frogs sequester defensive alkaloids, unchanged, from dietary arthropods. In the Neotropics, myrmicine and formicine ants and the siphonotid millipede Rhinotus purpureus are dietary sources for alkaloids in dendrobatid poison frogs, yet the arthropod sources for Mantella poison frogs in Madagascar remained unknown. We report GC-MS analyses of extracts of arthropods and microsympatric Malagasy poison frogs (Mantella) collected from Ranomafana, Madagascar. Arthropod sources for 11 "poison frog" alkaloids were discovered, 7 of which were also detected in microsympatric Mantella. These arthropod sources include three endemic Malagasy ants, Tetramorium electrum, Anochetus grandidieri, and Paratrechina amblyops (subfamilies Myrmicinae, Ponerinae, and Formicinae, respectively), and the pantropical tramp millipede R. purpureus. Two of these ant species, A. grandidieri and T. electrum, were also found in Mantella stomachs, and ants represented the dominant prey type (67.3% of 609 identified stomach arthropods). To our knowledge, detection of 5,8-disubstituted (ds) indolizidine iso-217B in T. electrum represents the first izidine having a branch point in its carbon skeleton to be identified from ants, and detection of 3,5-ds pyrrolizidine 251O in A. grandidieri represents the first ponerine ant proposed as a dietary source of poison frog alkaloids. Endemic Malagasy ants with defensive alkaloids (with the exception of Paratrechina) are not closely related to any Neotropical species sharing similar chemical defenses. Our results suggest convergent evolution for the acquisition of defensive alkaloids in these dietary ants, which may have been the critical prerequisite for subsequent convergence in poison frogs between Madagascar and the Neotropics.

Alkaloids↗

PubMed2001

Divergent and convergent evolution of NK-cell receptors.

Natural killer (NK)-cell receptors specific for major histocompatibility complex (MHC) class I molecules have been identified in humans and mice. Some of the most important receptors are structurally unrelated in the two species: the murine Ly-49 receptors are C-type lectins, while human killer-cell inhibitory receptors (KIRs) belong to the immunoglobulin superfamily. Here, Roland Barten and colleagues describe the divergent and convergent evolution of NK-cell receptors.

Animals↗

PubMed2004

Comparison of sea anemone and scorpion toxins binding to Kv1 channels: an example of convergent evolution.

Comparison of data from functional mapping carried out on scorpion and sea anemones toxins blocking currents through voltage-gated potassium channels revealed that, despite their different 3D structures, the binding cores of these toxins displayed some similarities. Further molecular modeling studies suggested that these similarities reflect the use by these toxins of a common binding mode to exert their blocking function. Therefore, scorpion and sea anemone toxins offer an example of mechanistic convergent evolution.

Amino Acid Sequence↗

PubMed2006

Ancient origin of reggie (flotillin), reggie-like, and other lipid-raft proteins: convergent evolution of the SPFH domain.

Reggies (flotillins) are detergent-resistant microdomains involved in the scaffolding of large heteromeric complexes that signal across the plasma membrane. Based on the presence of an evolutionarily widespread motif, reggies/flotillins have been included within the SPFH (stomatin-prohibitin-flotillin-HflC/K) protein superfamily. To better understand the origin and evolution of reggie/flotillin structure and function, we searched databases for reggie/flotillin and SPFH-like proteins in organisms at the base and beyond the animal kingdom, and used the resulting dataset to compare their structural and functional domains. Our analysis shows that the SPFH grouping has little phylogenetic support, probably due to convergent evolution of its members. We also find that reggie/flotillin homologues are highly conserved among metazoans but are absent in plants, fungi and bacteria, where only proteins with "reggie-like" domains can be found. However, despite their low sequence similarities, reggie/flotillin and "reggie-like" domains appear to subserve related functions, suggesting that their basic biological role was acquired independently during evolution.

Amino Acid Sequence↗

PubMed2004

Biomechanical evidence for convergent evolution of the invasive growth process among fungi and oomycete water molds.

Diverse microorganisms traditionally called fungi are recognized as members of two kingdoms: mushroom-forming species and their relatives in the Fungi, and oomycete water molds in the Stramenopila. Phylogenetic analysis suggests that these kingdoms diverged early in the evolution of eukaryotes. The phylogenetic detachment of the fungi and oomycetes is reflected in radical differences in their biochemistry, cell structure, and development. In terms of their biological activities, however, they show great similarity, because both groups form colonies of filamentous hyphae that invade and decompose solid food sources. Here we present biomechanical evidence of the convergent evolution of the invasive growth process in these microorganisms. Using miniature strain gauges to measure the forces exerted by single hyphae, we show that the hyphae of species in both kingdoms exert up to 2 atmospheres of hydrostatic pressure as they extend at their tips. No other eukaryotes have adopted this process for meeting their nutritional needs.

Biological Evolution↗