Predator-prey relationships and the evolution of colour polymorphism: a comparative analysis in diurnal raptors

Genetically based variation in coloration occurs in populations of many organisms belonging to various taxa, including birds, mammals, frogs, molluscs, insects and plants. Colour polymorphism has evolved in raptors more often than in any other group of birds, suggesting that predator–prey relationships was a driving evolutionary force. Individuals displaying a new invading colour morph may enjoy an initial foraging advantage because prey have difficulties in learning the colour of a rare morph (apostatic selection), or because morphs provide alternative foraging benefits allowing differently coloured individuals to exploit distinct food niches (disruptive selection). Plumage polymorphism should therefore have evolved in species that prey upon animals having the physiological ability to distinguish between differently coloured predators but also to flee once a predator has been detected. From this assumption, we can predict that closely related polymorphic and monomorphic species prey upon different animals. They may also differ in morphology, because foraging upon different prey may require different foraging modes, and in turn different morphological structures. We tested these two predictions in a comparative study of raptors. As expected, polymorphic and monomorphic species had a different diet, and there was a difference in wing length between polymorphic and monomorphic species within two genera ( Buteo and Accipiter ). Across all raptors for which phylogenetic relationships are known, polymorphic species preyed more often upon mammals than did monomorphic ones. These two types of raptor did not differ in the frequency of birds, insects and reptiles in their diets. We discuss these results in the light of the hypothesis that predator–prey relationships played a role in the evolution of colour polymorphism. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 565–578.     

The taxonomic treatment of agamosperms in the genusLimonium mill. (Plumbaginaceae)

Agamospermous species account for a large proportion of the species ofLimonium. Agamospermy is indicated by uneven polyploidy or aneuploidy, low pollen stainability and by the presence of monomorphic self-incompatible populations. The taxonomic treatment of agamospermous taxa varies from recognition of all of them at the same specific rank or by utilising a range of ranks in the taxonomic hierarchy. The influence of evolutionary hypotheses on taxonomic systems is considered. Molecular data provide a means of measuring the genetical relationships of taxa and establishing groups in a taxonomic hierarchy.     

Electrophoretic mobility shift in native gels indicates calcium-dependent structural changes of neuronal calcium sensor proteins

In proteins of the neuronal calcium sensor (NCS) family, changes in structure as well as function are brought about by the binding of calcium. In this article, we demonstrate that these structural changes, solely due to calcium binding, can be assessed through electrophoresis in native gels. The results demonstrate that the NCS proteins undergo ligand-dependent conformational changes that are detectable in native gels as a gradual decrease in mobility with increasing calcium but not other tested divalent cations such as magnesium, strontium, and barium. Surprisingly, such a gradual change over the entire tested range is exhibited only by the NCS proteins but not by other tested calcium-binding proteins such as calmodulin and S100B, indicating that the change in mobility may be linked to a unique NCS family feature—the calcium–myristoyl switch. Even within the NCS family, the changes in mobility are characteristic of the protein, indicating that the technique is sensitive to the individual features of the protein. Thus, electrophoretic mobility on native gels provides a simple and elegant method to investigate calcium (small ligand)-induced structural changes at least in the superfamily of NCS proteins.     

Chemotaxonomical relationships between penguins and tubenoses

The compositions of the uropygial gland wax of seven species of birds of the order Procellariiformes (tubenoses) belonging to four different families are compared with one another and with those of birds belonging to other orders. The results are discussed from a chemotaxonomical viewpoint. For this purpose, the various parameters have been depicted on a 3-dimensional matrix. Although all birds investigated are obviously related to each other, two of the species (Diomedea and Garrodia) also show a relationship to different orders. The results support the opinion that the Procellariiformes are closely related to the Sphenisciformes (penguins).     

A meta-analysis of spatial relationships in species richness across taxa: Birds as indicators of wider biodiversity in temperate regions

AimIndicators are an important tool by which conservationists monitor biodiversity because resources and expertise needed to survey biodiversity in a more direct way are often lacking. We aim to examine the effectiveness of species richness in birds as an indicator of species richness in other taxa. Birds are perhaps the most widely monitored species group so it is important to understand whether they can act as surrogates for distribution and abundance of other taxa.MethodsWe use a meta-analytical approach to assess the effectiveness of birds as indicators of cross-taxonomic species richness on spatial data from terrestrial temperate studies.ResultsThe literature showed mixed results but, in general, species richness in birds only weakly reflected species richness in other taxa. On average 19% of the variation in total species richness in other taxa was explained by species richness in birds. This is marginally higher than results found in a previous meta-analysis of species richness correlations between all taxa. Birds were more effective at reflecting cross-taxa species richness in study areas that were dominated by agricultural mosaics or mixtures of habitat types; they were less effective in forests and grassland environments. Overall, birds were better at reflecting species richness in mammals than other taxa, and relationships were more effective at larger spatial scales.Main conclusionsSpecies richness in birds only weakly reflected that of other taxa. Birds might be most useful as indicators of spatial variation in wider biodiversity in relatively patchy environments and for taxa that have similar spatial requirements. Species richness is one of many potential metrics for measuring biodiversity. There is a need to assess whether temporal change in bird populations and assemblages, as opposed to spatial variation, reflects change in other taxa and to identify elements of biodiversity for which birds could be the most effective surrogates.     

Kleptoparasitic interactions throughout the animal kingdom and a re-evaluation, based on participant mobility, of the conditions promoting the evolution of kleptoparasitism

Understanding of the conditions encouraging the evolution of kleptoparasitism has been limited by the preponderance of attention focused on a limited number of taxa (predominantly birds). However, most animal taxa contain kleptoparasitic members. In many ways, adult birds are aberrant because most are acrobatic, capable of three-dimensional movement, and steal from hosts that are capable of similar feats. The mobility of kleptoparasites and their hosts falls along a continuum, with the acrobatic birds at one end and sessile hosts and kleptoparasites at the other. Considering sedentary systems requires amendments to the criteria previously outlined as necessary for kleptoparasitism. Kleptoparasitic interactions between agile participants are ephemeral, involve numerous hosts over the lifetime of the kleptoparasite, and usually rely on vision. Large concentrations of hosts and large, high-quality food items are important in mobile systems. By contrast, the long-term, intimate associations of sedentary interactions demand that the host not consume the kleptoparasite's offspring and that the host must either have a longer life cycle than the kleptoparasite or be located in aggregations that have staggered life cycles (so the kleptoparasite can move to a new host when the original host dies). Expanding studies of kleptoparasitism to other taxa will differentiate between the selective pressures and evolutionary responses that are universal among kleptoparasitic symbioses and those that are restricted to certain groups.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 745–762.     

The evolution of the social brain: anthropoid primates contrast with other vertebrates

The social brain hypothesis argues that large brains have arisen over evolutionary time as a response to the social and ecological conflicts inherent in group living. We test predictions arising from the hypothesis using comparative data from birds and four mammalian orders (Carnivora, Artiodactyla, Chiroptera and Primates) and show that, across all non-primate taxa, relative brain size is principally related to pairbonding, but with enduring stable relationships in primates. We argue that this reflects the cognitive demands of the behavioural coordination and synchrony that is necessary to maintain stable pairbonded relationships. However, primates differ from the other taxa in that they also exhibit a strong effect of group size on brain size. We use data from two behavioural indices of social intensity (enduring bonds between group members and time devoted to social activities) to show that primate relationships differ significantly from those of other taxa. We suggest that, among vertebrates in general, pairbonding represents a qualitative shift from loose aggregations of individuals to complex negotiated relationships, and that these bonded relationships have been generalized to all social partners in only a few taxa (such as anthropoid primates).     

Cenozoic mystery birds – on the phylogenetic affinities of bony‐toothed birds (Pelagornithidae)

Mayr, G. (2011) Cenozoic mystery birds – on the phylogenetic affinities of bony‐toothed birds (Pelagornithidae). —Zoologica Scripta, 40, 448–467. The extinct Cenozoic bony‐toothed birds (Pelagornithidae) are characterized by the occurrence of unique spiky projections of the osseous jaws and are among the most distinctive neornithine taxa. Earlier authors considered these marine birds to be most closely related to ‘Pelecaniformes’ or Procellariiformes, but recent phylogenetic analyses resulted in a sister group relationship to Anseriformes. This latter hypothesis was, however, coupled with a non‐monophyly of galloanserine or even neognathous birds, which is not supported by all other current analyses. The character evidence for anseriform affinities of pelagornithids is thus reassessed, and it is detailed that the alleged apomorphies cannot be upheld. Pelagornithids lack some key apomorphies of galloanserine birds, and analysis of 107 anatomical characters did not support anseriform affinities, but resulted in a sister group relationship between Pelagornithidae and Galloanseres. By retaining a monophyletic Galloanseres, this result is in better accordance with widely acknowledged hypotheses on the higher‐level phylogeny of birds. The (Pelagornithidae + Galloanseres) clade received, however, only weak bootstrap support, and some characters, such as the presence of an open frontoparietal suture, may even support a position of Pelagornithidae outside crown‐group Neognathae.     

Deciphering primate phylogeny from macromolecular specificities

A problem in deciphering primate phylogeny, morphological convergence between different evolutionary lines, can be overcome by species comparisons of proteins, macromolecules with specificities closely linked to the genetic code in DNA. Various chemical, electrophoretic, and immunological data on serum and tissue proteins in primates are reviewed with respect to their phylogenetic significance. Much of this data deals with protein specificities in the Hominoidea and depicts a particularly close genetic relationship between man and the African apes. Hominoidea, Cercopithecoidea, Ceboidea, and Lorisoidea are characterized by their proteins as monophyletic or natural taxa, even though the conventional subdivisions within several of these superfamilies are not in complete accord with the protein analyses. The protein evidence supports the conventional grouping of Cercopithecoidea with Hominoidea in the infraorder Catarrhini and the grouping of Catarrhini and Platyrrhini (Ceboidea) in the suborder Anthropoidea. Lemuroidea and Lorisoidea appear to be closer to one another than to either Tupaioidea or Anthropoidea and closer to the Anthropoidea than to the Tupaioidea. Comparisons of primate DNA's by Hoyer and coworkers are demonstrating genetic affinities among primates which agree with those deduced from the comparison of protein specificities. Species differences and similarities in the relative amounts of different protein macromolecules reflect the grade relationships of primates, but, unlike the comparisons of amino-acid sequences or antigenic specificities, are not reliable indicators of phyletic affinities. Data on the ratios of M(uscle) to H(eart) type lactate dehydrogenase in a series of primate brains provides a biochemical example of the concept that there are “lower” (primitive) and “higher” (advanced) grades of evolutionary development among the extant primates.     

How do Plants Organize Microtubules Without a Centrosome？

A microtubule nucleates from a γ-tubuUn complex, which consists of γ-tubulin, proteins from the SPC971SPC98 family, and the WD40 motif protein GCP-WD. We analyzed the phylogenetic relationships of the genes encoding these proteins and found that the components of this complex are widely conserved among land plants and other eukaryotes. By contrast, the interphase and mitotic arrays of microtubules in land plants differ from those in other eukaryotes. In the interphase cortical array, the majority of microtubules nucleate on existing microtubules in the absence of conspicuous microtubule organizing centers （MTOCs）, such as a centrosome. During mitosis, the spindle also forms in the absence of conspicuous MTOCs. Both poles of the spindle are broad, and branched structures of microtubules called microtubule converging centers form at the poles. In this review, we hypothesize that the microtubule converging centers form via microtubule-dependent microtubule nucleation, as in the case of the interphase arrays. The evolutionary insights arising from the molecular basis of the diversity in microtubule organization are discussed.     

Four gel systems for electrophoretic fractionation of membrane proteins using ionic detergents

Membrane proteins were fractionated electrophoretically in polyacrylamide gels containing either anionic or cationic detergent at either pH 2.4 or 8.3. In all four systems, polypeptides migrated as monomers bearing the charge of the detergent ion and semi-logarithmic molecular weight–mobility relationships pertained. Electrophoresis of erythrocyte membrane proteins in these systems yielded very similar protein staining patterns but revealed significant differences in sialoglycoprotein migration.     

Sequence variation in the coding region of the melanocortin-1 receptor gene (MC1R) is not associated with plumage variation in the blue-crowned manakin (Lepidothrix coronata)

Avian plumage traits are the targets of both natural and sexual selection. Consequently, genetic changes resulting in plumage variation among closely related taxa might represent important evolutionary events. The molecular basis of such differences, however, is unknown in most cases. Sequence variation in the melanocortin-1 receptor gene (MC1R) is associated with melanistic phenotypes in many vertebrate taxa, including several avian species. The blue-crowned manakin (Lepidothrix coronata), a widespread, sexually dichromatic passerine, exhibits striking geographic variation in male plumage colour across its range in southern Central America and western Amazonia. Northern males are black with brilliant blue crowns whereas southern males are green with lighter blue crowns. We sequenced 810 bp of the MC1R coding region in 23 individuals spanning the range of male plumage variation. The only variable sites we detected among L. coronata sequences were four synonymous substitutions, none of which were strictly associated with either plumage type. Similarly, comparative analyses showed that L. coronata sequences were monomorphic at the three amino acid sites hypothesized to be functionally important in other birds. These results demonstrate that genes other than MC1R underlie melanic plumage polymorphism in blue-crowned manakins.     

On the Identification of α- and β-Tubulin Subunits

Abstract: Confusion appears to have arisen in the literature regarding the designation of α-and β-tubulin in polyacrylamide gels. The presence or absence of 8 M-urea in sodium dodecyl sulfate (SDS) polyacrylamide gels leads to different patterns for unalkylated tubulin subunits (and other proteins), making difficult the designation of the α and β subunits by original definition using electrophoretic mobility in the molecular weight dimension. The specific biochemical property of posttranslational tyrosylation of the α subunit has been used to identify further this subunit. Under all conditions tested, the β subunit has been found to be more acidic than the α subunit, with isoelectric point differences that agree with theoretical and published values. If the tubulin subunits are reduced and alkylated, the β subunit migrates more rapidly in SDS polyacrylamide gels, with or without urea present. However, unalkylated tubulin subunits can comigrate or even reverse their relative mobility if 8 M-urea-SDS polyacrylamide gels are used for subunit separation. The results also confirm the earlier reports that the post-translational tyrosylation of protein appears exclusively restricted to α-tubulin and can be demonstrated in an in vivo situation. In addition, the results suggest that only the α₂ subunit of tubulin is tyrosylated.     

Biochemical characterization of a protein of albumin multigene family from serum of African catfish Clarias gariepinus Bloch

A monomorphic albumin-like protein (CfSA) has been purified to homogeneity from the serum of African air-breathing catfish Clarias gariepinus Bloch. It has a molecular mass of approximately =70 kD and shows a lesser electrophoretic mobility than human serum albumin (HSA) in native gels. The protein exhibits cross-reactivity against rabbit anti-HSA serum and shows considerable similarity with HSA in secondary structure, however, with some differences, as indicated by a slight shift in the peaks around 267 nm and 278 nm and the absence of shoulders at 276 and 283. A certain degree of similarity also exists between their tertiary structures with respect to aromatic asymmetric environment as indicated by far-UV CD spectra and the visible range CD spectra of bilirubin complexes. CfSA-bilirubin complex is mainly characterized by bisignate CD Cotton effects (CDCEs), having minima and maxima wavelengths at 406 and 486 nm, respectively and unlike HSA, it shows prominent additional maxima around 426 nm. Based on the number of sulfhydryls, CfSA is in the rank of advanced teleosts. The occurrence of albumin in C. gariepinus in relation to the evolutionary dichotomy of albumin and other members of its multigene family in class Pisces has been discussed.     

PHYLOGENY AND FORELIMB DISPARITY IN WATERBIRDS

Previous work has shown that the relative proportions of wing components (i.e., humerus, ulna, carpometacarpus) in birds are related to function and ecology, but these have rarely been investigated in a phylogenetic context. Waterbirds including “Pelecaniformes,” Ciconiiformes, Procellariiformes, Sphenisciformes, and Gaviiformes form a highly supported clade and developed a great diversity of wing forms and foraging ecologies. In this study, forelimb disparity in the waterbird clade was assessed in a phylogenetic context. Phylogenetic signal was assessed via Pagel's lambda, Blomberg's K, and permutation tests. We find that different waterbird clades are clearly separated based on forelimb component proportions, which are significantly correlated with phylogeny but not with flight style. Most of the traditional contents of “Pelecaniformes” (e.g., pelicans, cormorants, and boobies) cluster with Ciconiiformes (herons and storks) and occupy a reduced morphospace. These taxa are closely related phylogenetically but exhibit a wide range of ecologies and flight styles. Procellariiformes (e.g., petrels, albatross, and shearwaters) occupy a wide range of morphospace, characterized primarily by variation in the relative length of carpometacarpus and ulna. Gaviiformes (loons) surprisingly occupy a wing morphospace closest to diving petrels and penguins. Whether this result may reflect wing proportions plesiomorphic for the waterbird clade or a functional signal is unclear. A Bayesian approach detecting significant rate shifts across phylogeny recovered two such shifts. At the base of the two sister clades Sphenisciformes + Procellariiformes, a shift to an increase evolutionary rate of change is inferred for the ulna and carpometacarpus. Thus, changes in wing shape begin prior to the loss of flight in the wing‐propelled diving clade. Several shifts to slower rate of change are recovered within stem penguins.     

Basal divergences in birds and the phylogenetic utility of the nuclear RAG-1 gene.

The single-copy RAG-1 gene is found throughout higher vertebrates and consists of a single 3.1-kb exon without intervening introns. A 2.9-kb region of the RAG-1 locus was sequenced for 14 basal taxa of birds plus the crocodylian outgroups Alligator and Gavialis. Phylogenetic analysis of the sequences supported the hypothesis that the deepest evolutionary split in extant birds separates paleognaths from neognaths. A deep division among neognaths separates the chicken- and duck-like birds ("galloanserines") from a clade consisting of all other birds ("plethornithines"). The relationships of these three basal clades in Aves were supported by high bootstrap (98 to 100%) and large decay index values (above 14). Additionally, the plethornithine clade is characterized by a 15-bp (five-codon) synapomorphic deletion relative to all other birds. RAG-1 evolves slowly, with a number of properties favoring its phylogenetic utility, including rarity of indels, minimal saturation of transition changes at 3rd positions of codons, nearly constant base composition across taxa, and no asymmetry in directional patterns of reconstructed change. However, RAG-1 does not evolve in a clocklike manner, suggesting that this gene cannot easily be used for estimating ages of ancient lineages.     

EGG COMPOSITION AND HATCHLING PRECOCITY IN SEABIRDS*

This paper presents analyses of the composition (shell, yolk, albumen) and of the quality (lipid, protein and water contents) of yolk and albumen of eggs of 25 species of seabirds belonging to the Sphenisciformes, Procellariiformes, Pelecaniformes, and Lari of the Charadriiformes. These data are compared with those published for species in the same orders and suborders, and the combined seabird data are compared with published data for non-seabirds. Variation in the proportionate weight of eggshell is not related to hatchling precocity but is probably due to adaptive differences in nest substratum and the agility of the incubating birds. Lipid and protein contents of yolk, and water content of albumen, are uniform in eggs of all examined species. Protein levels of albumen and water content of yolk and of entire egg contents vary greatly between taxa. Contrary to previous claims there is no simple relationship between egg composition and hatchling precocity. Differences in egg composition will probably only be clearly understood when the nutritional needs of the embryo, and of the hatchling in the time before it regularly obtains food, are known.     

Characterization by isoelectric focusing of chorion protein variants inDrosophila melanogaster and their use in developmental and linkage analysis

Summary Drosophila melanogaster chorion proteins are characterized on one-dimensional isoelectric focusing (IF) gels. The six major chorion components previously identified on SDS gels are shown to resolve into at least 11 components in our IF system. IF screening of 102 geographic strains ofDrosophila melanogaster revealed seven cases of variation in major chorion components. Two strains, Crimea and Falsterbo, which were monomorphic for a variant B1 protein and two strains, Skafto and Lausanne, which were monomorphic for a variant C1 protein, were chosen for further study. After IF developmental analysis of F1 hybrids had indicated that the sources of the variation resided in the structural genes for these proteins, each variant was crossed to a multiply marked and inverted strain (BLT) to determine the linkage group of the variant gene. To localize genes to more specific sites multiply marked 3rd (SKERO) or X-chromosomal (CB1) (X-PLE) mapping strains were used. In both Crimea and Falsterbo the gene for the B1 protein is located near map location 26 on the 3rd chromosome. In both Lausanne and Skafto the C1 gene is located on the X chromosome. Hence, for the first time, we have demonstrated genetically the non-linkage of two chorion genes, B1 and C1.     

Disc-electrophoresis of albumin and globulin fractions from dormant achenes of Lasthenia

Albumin and globulin fractions were extracted from dormant seeds of all 20 taxa of Lasthenia. After disc-electrophoresis on basic 7% acrylamide gels, mean R_p values, coefficients of variation and 95% confidence intervals were computed for both types of protein bands. Dendrograms were produced using similarity coefficients, indicating interspecific affinities among the taxa which differ from the sectional taxonomy of the genus. Protein data concerning certain problematical relationships are compared with published taxonomical and chemical data.     

The evolutionary radiation of modern birds (Neornithes): reconciling molecules, morphology and the fossil record

The pattern, timing and extent of the evolutionary radiation of anatomically modern birds (Neornithes) remains contentious: dramatically different timescales for this major event in vertebrate evolution have been recovered by the 'clock-like' modelling of molecular sequence data and from evidence extracted from the known fossil record. Because current synthesis would lead us to believe that fossil and nonfossil evidence conflict with regard to the neornithine timescale, especially at its base, it is high time that available data are reconciled to determine more exactly the evolutionary radiation of modern birds. In this review we highlight current understanding of the early fossil history of Neornithes in conjunction with available phylogenetic resolution for the major extant clades, as well as recent advancements in genetic methods that have constrained time estimates for major evolutionary divergences. Although the use of molecular approaches for timing the radiation of Neornithes is emphasized, the tenet of this review remains the fossil record of the major neornithine subdivisions and better-preserved taxa. Fossils allowing clear phylogenetic constraint of taxa are central to future work in the production of accurate molecular calibrations of the neornithine evolutionary timescale.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 153–177.