Welcome to the first Weekly Science Roundup. These regular posts will consist of quick summaries of interesting papers, articles, and blog posts which I encounter during the preceding week (sometimes they may have been published earlier). The number of items that I mention will vary, and there will be an obvious bias towards biology (especially marine ecology), but I will try to keep things broad!
Hopefully, these should appear on a weekly basis (!) and initially I’ll try and post each edition on Sunday.
From the journals:
Male chimpanzees form enduring social bonds
A ten year study of a large group of chimpanzees in Kibale National Park, Uganda, has found that male chimpanzees form enduring social relationships which are not consistent with some recent suggestions that primates in general only form short-term bonds to serve their immediate needs. Some pairs of males showed strong social bonds, spending above average amounts of time together over periods of several years, and such pairs often showed a greater degree of equality in their grooming behaviour. These interactions were affected by kinship; males who shared a genetic mother formed longer lasting and more equitable bonds. However, unrelated males still formed strong bonds, with individual males typically having at least one long-lived association, some of which lasted the entire length of the study period.
J. C. Mitani, Male chimpanzees form enduring and equitable social bonds, Animal Behaviour (2009), DOI: 10.1016/j.anbehav.2008.11.021
Harvesting for human usage drives rapid phenotypic change in wild populations
Many species are heavily harvested by humans for food or other purposes. This pressure results in a variety of negative effects, among which are changes in morphological traits (such as size), and life history traits (such as age/size at first reproduction). On average individuals in a population become smaller and breed earlier as the larger and later reproducing individuals are consistently removed from the environment in large numbers. Since larger, later maturing individuals often have greater reproductive success over their lifetimes, this exacerbates ongoing declines in population size. An analysis of data on these trait changes in several exploited populations has compared them with those occurring in populations affected by natural perturbations (such as Galapagos finches hit by droughts) and found that changes driven by human exploitation are greater in extent, and – critically – occurring over much shorter timescales.
C. T. Darimont, S. M. Carlson, M. T. Kinnison, P. C. Paquet, T. E. Reimchen and C. C. Wilmers, Human predators outpace other agents of trait change in the wild, Proceedings of the National Academy of Sciences (2009), doi: 10.1073/pnas.0809235106
Camouflage requires corresponding behaviour in order to be truly effective
While it might seem a trivial observation that camouflage is only really effective when you keep still, there is little rigorous data on the association between crypsis and behaviour – and how the interaction between these two factors affects the risk of predation. Experiments involving three-spined sticklebacks (Gasterosteus aculeatus) feeding on insect larvae, verified that the effectiveness of cryptic colouration was dependent upon how much the prey moved around. Motionless and cryptic prey were seldom eaten – while moving about rendered their camouflage ineffective (in comparison motion had little, if any, effect on how likely non-camouflaged prey were to be eaten). Cryptic colouration is a common anti-predator defence – but is only really effective in conjunction with suitable behaviour, indicating that such behaviour must co-evolve with the morphological adaptations.
C. C. Ioannou and J. Krause, Interactions between background matching and motion during visual detection can explain why cryptic animals keep still, Biology Letters (2009), doi: 10.1098/rsbl.2008.0758
From the blogosphere:
Hold the front page: Tree of life not an actual tree
New Scientist provoked the ire of several science bloggers this week, with the front page declaring “Darwin was wrong”. This was accompanied by an article explaining why the ‘Tree of Life’ analogy is flawed in several respects. Who knew? PZ Myers of Pharyngula was not impressed, Larry Moran at the Sandwalk blog went into a bit more detail about his problems with the headline, and Jason Rosenhouse of EvolutionBlog was fairly scathing in his assessment of the content of the article - “the article has only the yawn-worthy old-news that horizontal gene transfer among single-celled organisms means that the metaphor of a tree of life must be modified”.