• Sumatran orang-utans delay puberty to build up strength

    ANY teenage boy will confirm that older boys make it impossible to get the girls. Young male orang-utans with the same problem have a unique and unexpected solution: they don't grow up until they are strong enough to challenge the dominant males.

    Male orang-utans can reproduce from around age 15, but in order to attract a mate they also have to develop secondary sexual characteristics - the equivalent of men growing chest hair. These include conspicuous cheek flanges. Yet Sumatran orang-utans often delay acquiring flanges, sometimes for over 10 years. No other primates do this, not even Bornean orang-utans.

    Gauri Pradhan of the University of South Florida in Tampa and colleagues noted another difference between the species: unlike Bornean males, Sumatran males can monopolise females for weeks at a time. Pradhan built mathematical models of orang-utan populations from decades of field data, and varied the extent to which males could monopolise females. She found that males that could delay maturation did better when a few males controlled all the females. They gradually built up physical strength until they were capable of deposing the dominant males, at which point they matured (American Journal of Physical Anthropology, DOI: 10.1002/ajpa.22079). The model is simple yet solid, says Madeleine Hardus of the University of Amsterdam in the Netherlands.


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  • Hive and Seek: Domestic Honeybees Keep Disappearing, but Are Their Wild Cousins in Trouble, Too? [Slide Show]

    Is colony collapse disorder just the visible part of a "global pollinator crisis"? The answer is surprisingly murky. To help answer the question, scientists have created an inexpensive, nationwide wild bee monitoring program  

    01. Polyester Bees

    01. Polyester Bees



    Colletes bees are nicknamed "polyester bees" because they enclose their broods in a cellophanelike material that keeps out water and fungi....[More]

    thumb: 01. Polyester Bees
    thumb: 02. Cuckoos
    thumb: 03. Sweat Bees
    thumb: 04. Miners
    thumb: 05. Wool Carders
    thumb: 06. Honey Bees
    thumb: 07. Bumble Bees
    thumb: 08. Leaf Cutters
    thumb: 09. Carpenters
    thumb: 10. Long-Horns
    thumb: 11. Masked Bees
    thumb: 12. Small Leaf Cutters
    thumb: 13. Squash Bees


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  • http://www.newscientist.com/article/dn21774-zoologger-jesus-bugs-evolved-hooks-for-grappling-eyes.html

    19:00 03 May 2012 by Michael Marshall
    For similar stories, visit the Zoologger Topic Guide

    Video: Watch water striders pin down females for sex

    Zoologger is our weekly column on curious cosmic objects, from the solar system to the far reaches of the multiverse

    Species: Rheumatobates rileyi
    Habitat: Skittering around on water throughout North America

    Our eyes are precious and vulnerable. We rely on them to understand and navigate the world, but they are soft and easily damaged.

    Simply having a stray eyelash is enough to stop us in our tracks while we get the thing out. Faced with blown dust or sand, we instinctively turn away or fling up our hands. Many people can't bear to watch the opening of Buñuel's Un Chien Andalou – you know, the bit with the razor.

    So female Rheumatobates rileyi are hardy little bugs. When males want to force them to mate, they grab them by the eyes. The females have compound eyes, so there's less risk of damage than there would be for us, but it's still thoroughly inconvenient. Worse, the males have evolved elaborate grasping apparatus to help them cling on.

    Jesus bugs

    R. rileyi belongs to a family of bugs called Gerridae – otherwise known as water striders, or Jesus bugs.

    They're famous for their habit of skating around on the surface of still water, particularly ponds and lakes. Their legs are unusually long, spreading their weight across a wide area. Tension in the water surface helps support them.

    In common with many other organisms, male striders want to mate as often as possible, perhaps 30 times a day, to inseminate lots of females. But each female only wants to mate about once a week: she can store sperm so she doesn't need any more sex than that.

    This conflict has affected water striders' evolution, with males evolving ways to restrain the females and females developing ways to resist. In one species, the males have to spend 15 minutes tapping rhythms on the water surfacebefore the females put out.

    Don't hold me

    In R. rileyi, the conflict has produced a similarly extreme result. The males have massively modified antennae which, as well as sensing the environment, are used for grabbing hold of females. Locke Rowe of the University of Toronto, Canada, used electron microscopes and high-speed videos to find out how the antennae work.

    Instead of being straight, the antennae bend back on themselves to form a hook that fits neatly around the female's eye. Each hook-like antenna has a small spike and hook protruding from the main length, which lock into the female's body. They also have a pad covered with hair-like setae, which creates friction and helps maintain the grip.

    Rowe looked at developing R. rileyi and found that a gene called dll was expressed in their antennae. He used a genetic trick called RNA interference to reduce the gene's activity in developing males, and found that doing so simplified the antennae. When the effect was strong, all of the adaptations disappeared.

    Gene for grabbing

    Other than their simplified antennae, the modified males were pretty normal. So Rowe introduced them to females to see how they did. Compared to normal males, with their elaborate antennae, the modified males were less successful at mating with females, and produced fewer offspring.

    That means a single gene, dll, seems to be responsible for the males' hugely elaborate antennae. It acts late in development, by which time its other functions are done and dusted. That may explain why it has changed so much in R. rileyi: it only affects one thing, so it's easy for evolution to modify it without causing harmful effects.

    One thing's clear, though: it hasn't worked that well. Even the fully-evolved males don't mate very often. "They're only successful 10 per cent of the time," Rowe says. "The females are so effective at dislodging males."That's because unwanted matings increase the risk of a predator attacking, force the female to carry a male on her back, and increase her risk of sexually transmitted infections.

    Journal reference: Science DOI: 10.1126/science.1217258

    If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

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    Male Rheumatobates rileyi bugs (left) use hooks on their antennae (shown in purple) to grab females' eyes and mate with them (Image: Science/AAAS)

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  • http://www.pourlascience.fr/ewb_pages/a/actualite-un-spinosaure-en-asie-29750.php

    Un spinosaure, dinosaure à « gueule de crocodile », aurait pour la première fois été découvert en Asie.

    Loïc Mangin
    © Michel Fontaine

    Ichthyovenator laosensis.

    Pour en savoir plus

    R. Allain et al.The first definitive Asian spinosaurid (Dinosauria : Theropoda) from the early Cretaceous of LaosNaturwissenschaften, prépublication en ligne, 18 avril 2012.


    Loic Mangin est rédacteur en chef adjoint au magazine Pour la Science.

    Égypte, Angleterre, Niger et Brésil : ce sont les seuls pays où l'on avait découvert des spinosaures, dont le célèbre baryonyx, des dinosaures carnivores au museau allongé et muni de dents proches de celles des crocodiles. Dès lors, on imagina que le continent asiatique n'avait hébergé aucun de ces reptiles. C'était une erreur ! Ronan Allain, du Muséum national d'histoire naturelle (CNRS/UPMC), Thiengkham Xaisanavong, du Musée des dinosaures de Savannakhet, au Laos, et leurs collègues ont mis au jour un spinosaure à Tang Vay, au Laos.

    L'animal est nommé Ichthyovenator laosensis, soit « le chasseur laotien de poissons », en référence à son régime piscivore. Outre leur « gueule de crocodile », les spinosaures se distinguent le plus souvent par une voile, à fonction que l'on suppose décorative, portée par des prolongements osseux (des épines neurales) des vertèbres dorsales et caudales. Cette spécificité a conduit les paléontologues à l'identification du fossile.

    Précisons que cette découverte, qui prouve la présence de spinosaures en Asie, et donc dans le monde entier, valide les travaux du paléontologue français Eric Buffetaut : avec Rucha Ingavat, il avait formulé cette hypothèse dès 1986, sur la base de dents mises au jour en Thaïlande.

    Ronan Allain et Philippe Richir, au Musée des dinosaures de Savannakhet, décrivent quelques os de Ichthyovenator laosensis.



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  • Le cerveau des insectes est capable de fabriquer et de manipuler des concepts(1) abstraits. Il peut même utiliser simultanément deux concepts différents afin de prendre une décision face à une situation nouvelle. Ce résultat totalement inattendu a été obtenu par l'équipe du professeur Martin Giurfa au centre de recherches sur la cognition animale (CNRS/Université Toulouse III - Paul Sabatier)(2). Cette capacité, que l'on croyait propre aux humains et à quelques primates, montre que des analyses cognitives sophistiquées sont possibles en l'absence de langage et malgré une architecture neurale miniaturisée. Ces travaux, publiés dans la revue PNAS, remettent en cause de nombreuses théories dans des domaines tels que la cognition animale, la psychologie humaine, les neurosciences et l'intelligence artificielle.



    Les abeilles sont capables de maîtriser des concepts abstraits, telles les notions de position relative et de différence, ce qui remet en cause les liens entre capacités cognitives et complexité cérébrale.

    Guillaume Jacquemont


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