WordPress must have changed something, because HTML anchors that allow you to skip to a section in the page get stripped out. Probably a safety feature, confusing the # for a Java command. This means no more index, it’s pointless now. Sorry.
These are papers that may be of general interest published this week, with commentary as necessary. No specific case studies, overly specialised research, or taxonomic papers. Papers ordered only by their appearance in my inbox. For PDFs, e-mail me, I get most of them. You can request an in-depth analysis of any paper and I’ll do it as I get the time.
Open-access papers, those that are free to read/download even without an academic connection, are tagged with [OA] for easy finding with your browser’s text search (Ctrl+F).
24 papers this week, 9 of them open access.
- Freiwald & Roberts. 2005. Cold-Water Corals and Ecosystems. [Marine Biology]
- Griffin DH. 1996. Fungal Physiology. [Protists, Protozoa, Fungi]
- Hennig W. 1981. Insect Phylogeny. [Insects; Phylogeny]
- Wisshak M. 2006. High-Latitude Bioerosion: The Kosterfjord Experiment. [Marine Biology]
For those interested in how natural selection works at the genomic level, read the four papers here. All of them are [OA] to boot!
The more of these kinds of paper I read, the more I begin to realise that findigna consistent pattern for deep sea colonisation will be very difficult. This one finds that some isopod groups have been in the deep sea for at least over 200 million years. Riehl & Kaiser (2012) find that many isopod groups colonised the deep sea recently. So yeah, next time you read a generalisation about the colonisation of the deep sea, dismiss it.
Galls are one of the most fascinating phenomena in biology. They’re caused by insects that manipulate plant physiology to form these habitats for their eggs, larvae, or even adults. In effect, they’re examples of parasitism of insects on plants. This paper finds that the completely closed gall caused by aphids that live their entire lives in it isn’t just a convenient shelter. The modification is so deep that the inner surface of the gall is changed to become water-absorbant, thereby cleaning the gall of excess water and avoiding drowning.
Some more gall awesomeness. The aphids up there have modified the structure of the plant so it maintains the gall’s humidity. The wasps in this paper use the plant’s photosynthetic abilities to maintain the gall atmosphere’s composition at optimal levels.
I personally think this is rather vague to refer to as convergent evolution, but that’s just a matter of opinion; the functional convergence is there. Check Hoy & Robert (1996) for a review of hearing in insects.
- Tagmatization in Stomatopoda — reconsidering functional units of modern-day mantis shrimps (Verunipeltata, Hoplocarida) and implications for the interpretation of fossils. [OA]
An update to my mantis shrimp post.
- Revival of Palaeoptera—head characters support a monophyletic origin of Odonata and Ephemeroptera (Insecta).
I mentioned the Palaeoptera hypothesis in this post, favouring the Metapterygota hypothesis over it. This paper provides support for the Palaeoptera hypothesis, but based only on characters in the head. I always warn against considering only one source of data in phylogenetics, so I’llw ait for a full analysis before passing judgement – despite their having good justification for only considering the head.
Good party trivia, especially if said party has douchebags in it.
- Functional values of stabilimenta in a wasp spider, Argiope bruennichi: support for the prey-attraction hypothesis.
There are as many papers that support prey-attraction as those that do not. It’s probably something that’s species-specific, not phylogenetically-dependent.
Examining three well-described mechanisms with respect to epistasis and pleiotropy indicates that sign (or antagonistic) pleiotropy without epistasis cannot explain no-cost generalism and that magnitude pleiotropy without epistasis (including directional selection and mutation accumulation) cannot explain the persistence of specialism. However, pleiotropy with epistasis can explain all.
- Natural selection. V. How to read the fundamental equations of evolutionary change in terms of information theory. [OA]
I know, an article about sexual selection in an organism where there are no sexes sounds like a bit of a stretch, but rest assured that it does happen – wherever there is mating, there is the potential for sexual selection.
- Astronomically calibrated 40Ar/39Ar age for the Toba supereruption and global synchronization of late Quaternary records. [OA]
We report an astronomically calibrated 40Ar/39Ar age of 73.88 ± 0.32 ka (1σ, full external errors) for sanidine crystals extracted from Toba deposits in the Lenggong Valley, Malaysia, 350 km from the eruption source and 6 km from an archaeological site with stone artifacts buried by ash. If these artifacts were made by Homo sapiens, as has been suggested, then our age indicates that modern humans had reached Southeast Asia by ∼74 ka ago.
- Origin of life: hypothesized roles of high-energy electrical discharges, infrared radiation, thermosynthesis and pre-photosynthesis.
This paper is all hypothesis and speculation, so keep this in mind.
High-energy electrical discharges generated some simple organic molecules available for the origin of life. Infrared radiation, both incoming to the Earth and generated on the cooling Earth with day/night and warming/cooling cycles, was a component of heat engine thermosynthesis before enzymes and the genetic code were present. Eventually, a primitive forerunner of photosynthesis and the capability to capture visible light emerged.
A good review of the state of the art.
- ‘Further Development’ of Mendel’s legacy? Erich von Tschermak-Seysenegg in the context of Mendelian–biometry controversy, 1901–1906.
This paper, which I find to be very good in terms of methodology and thus with reliable conclusions, finds that eukaryotes are archaeans. This is in contrast to the typically-presented view (even by me!) of there being three domains: Bacteria, Archaea, and Eukarya, with the latter two closely-related. If this result stands, it would mean that Archaea is now paraphyletic, meaning it needs a new name. This hypothesis of eukaryotes beign archaeans isn’t new, it’s called the eocyte hypothesis. See Gribaldo et al. (2010) for more on the position of the eukaryotes.
This paper is important for understanding just how sauropods, the herbivorous dinosaurs with the really long necks and the largest land animals that ever lived, could even move their necks.
The transformation of the cervical ribs into ossified tendons makes the neck more flexible and implies that tension forces acted mainly along the length of the neck. [...] Tension forces would allow important neck muscles to shift back to the trunk region, making the neck much lighter.
- Late Cretaceous restructuring of terrestrial communities facilitated the end-Cretaceous mass extinction in North America.
It’s common in drunken invertebrate palaeontologist conversations to not really be concerned about the K-T extinction fo the non-avian dinosaurs, because those dinosaurs were already on their way out anyway. This paper gives more detail on that statement: the Late Cretaceous saw many environmental and biospheric changes, and the asteroid+volcanic eruptions combo coincidentally came at that fragile moment and shattered the turnovers.
Good party trivia here.
A good addendum to any discussion on the evolution of eyes, this is a paper on the evolution of the main photoreceptive pigments. No big surprises for the overall framework we have of the evolution of eyes.
Corneas of invertebrates, which have simple or compound eyes, or both, may be featureless or may possess microprojections in the form of nipples. It was previously unknown whether cephalopods (invertebrates with camera-type eyes like vertebrates) possess corneal microprojections and, if so, of what form. Using scanning electron microscopy, we examined corneas of a range of cephalopods and discovered nipple-like microprojections in all species. […] Their function may be to increase surface-area-to-volume ratio of corneal epithelial cells to increase nutrient, gas, and metabolite exchange, and/or stabilize the corneal mucous layer, as proposed for corneal microprojections of vertebrates.
Innate immunity is the hardcoded ability of the immune system of any animal to recognise foreign microorganisms as distinct from host cells and symbionts, usually done with receptors that recognise known structures on the cell membranes. This is in contrast to adaptive immunity, found only in vertebrates and which is done with T cells and immunoglobins that recognise any variety of antigens on cell surfaces and learn to react accordingly (they’re the reason why vaccination works!). Invertebrates have only innate immunity and have it so fine-tuned that they can foster a whole laod of symbionts yet still stay healthy; this paper explains how. Innate immunity isn’t all rosy though.
Fluorescent proteins have become some of the most important tools in cell biology, even netting their discoverers a Nobel Prize in Chemistry. This paper summarises their uses.