1. Wolbachia Parthenogenesis Mechanism
I mentioned Wolbachia, the parthenogenesis-inducing bacterium, in my parthenogenesis post. This paper proposes one mechanism by which it acts in Asobara japonica, a parasitoid wasp of drosophilid flies. The main finding is that the sex ratio of offspring was significantly skewed when the females mated with infected or uninfected males, with more males being born when females mated with an infected male. There were no cytological aberrations, such as diploidy of males or irregular spermatogenesis in the males. The most plausible hypothesis to explain the pattern is cytoplasmic incompatibility, in other words Wolbachia interferes with the sperm-egg interaction.
2. Heritable Sperm Variation in a Dung Beetle
Traits associated with sexual reproduction are remarkably diverse from both the male and female side. In males especially, genitals tend to diverge very quickly, as does sperm. There are multiple hypotheses available to explain this: the lock-and-key hypothesis (increasingly unlikely) which says that the female genitalia are a lock and the males have the key, to prevent interspecies copulation; pleiotropy, i.e. that the complexity of the genitals is just a side-effect of genetic changes elsewhere in the organism; or sexual selection. In the latter, there are three possible mechanisms: sperm competition, female choice, and conflict. They’re pretty self-explanatory. Onthophagus dung beetles, like the ones studied in this paper, are ideal for testing the various hypotheses, as the males are dimorphic. There are the majors, who are large, have horns and actively protect their female and cooperate in raising the offspring. There are also the minors, who are small, not horned and sneak copulations on the side and do not take care of the offspring. Because the females don’t have the ability to store or otherwise choose which sperm to use for fertilisation, sperm competition is expected to take a predominant role here. This is what this paper shows, first by characterising the differences in functional morphology between the sperm of major and minor males, and then showing that these differences are heritable and not just the result of phenotypic plasticity.
3. Manipulation of Plant Defences
I’ve already written a bit about plant-arthropod interactions. Plants have herbivore defences installed at all levels: their trichomes and thick cell walls are structural defences and many of their metabolites may be toxic. In addition, herbivores may induce specific defensive reactions in the plant. For example, when under attack, the plant releases volatile compounds that attracts predators, as well as producing all sorts of toxins that suppress the herbivore’s performance. This is known not only from observational studies but also from genetic studies: feeding triggers specific signalling pathways that results in the activation of defensive “behaviour”. Of course, the herbivore doesn’t just take this lying down: after all, natural selection has been acting on these for over 100 million years. The herbivores can suppress the defensive actions by the plant (and natural selection makes sure the plants get more vicious, etc.). The present paper shows something remarkable though: a pest herbivore, the spider mite Tetranychus evansi, not only suppresses the defense but also somehow affects the transcriptional pathways controlling the defences to manipulate the nutrient content of the plant, resulting in the plant being more nutritious and thus attacked more. Awesome.
4. Fossil Soil Community in Amber
I think it goes pretty much without saying that amber inclusions provide the most detailed look at past life, both at the individual morphology level and at the ecosystem level. For one spectacular example, there is a 100 Ma piece of amber from France with 86 diverse arthropods, 7 feathers, 181 microorganisms and various plants in it. This one piece can allow us to faithfully reconstruct food webs and other ecosystem-level features. Of course, this one piece is unique. Usually, inclusions are rare and we need to examine many pieces from the same locality to get such a complete picture. But when this is done, the result is something like this paper, which reconstructs the ecosystem of the Cretaceous Charentes amber forest. The most significant finding is that the ecosystem functioned much the same way as our modern ones, with taxa largely having the same roles back then as they do now. The notable difference is the lack of angiosperms, but that’s to be expected.
5. Following Stranger Pheromones
Hymenopterans often follow trails using pheromones. As individuals go along a trail, they lay tiny drops of a specific pheromone along the trail and this is detected by fellow individuals, which makes the trail more popular. This paper finds that this one species of stingless bee, Scaptotrigona pectoralis, can detect the pheromones of other species and follow the trails laid by them in order to find food, saving them the trouble of searching for food sources by themselves.
6. How Jewel Wasps Affect Cockroaches
I already talked about how jewel wasps manipulate cockroaches in my behaviour-affecting parasites post. This paper provides some evidence as to how the wasp’s venom affects the roach’s brain. It might act on the same pathway as opium does. The effects of opiates on insects are pretty complex, but when properly regulated, they control the escape response. The venom of the wasp seems to contain chemicals that interfere with the system, either stopping the production of opiates or causing too many opiates to be released – the data are ambiguous as to which is which. What this means is that only the escape response of the cockroach crashes – the roach still walks and grooms itself.
7. DNA Repair Observed in Real-Time
The breaking of the DNA double strand is always possible due to environmental or metabolic toxins, with a break causing immediate cell arrest, so it’s obvious that repair mechanisms exist. The most common is homologous recombination, which occurs during the S and G2 phases of the cell cycle (in the G1 phase, nonhomologous end-joining occurs instead). Cell biology is not my strong suit so I will not go into details here. Homologous recombination is what this paper is about. This is basically when homologous DNA molecules are used as a template and copied to repair the original DNA strand. The researchers here studied the detailed changes that occur at the molecular level.
8. Leaf Margin Development
The shape of the leaf margin is used to categorise the leaf: when the margins are complete or very slightly indented, they are simple leaves; those with more complex indentations are compound leaves. This paper proposes a convincing morphogenetic model for how these are formed (using the model plant Arabidopsis), invoking location- and time-specific expression of regulatory genes.
9. 1990s Boom in Antarctic Bryozoan Growth
Those who know the history of Antarctic exploration know of Robert Falcon Scott, the British dude who was second to get to the South Pole in 1912 (after the Norwegian Roald Amundsen) but died along with his whole crew over there. Along the way to Antarctica, his expedition collected many samples of the benthic fauna – this was actually the primary purpose of the trip, with reaching the South Pole only made a goal out of nationalistic pressure. The collected samples have survived and are present in various museum collections. The researchers in this paper measured the growth rates of the bryozoan Cellarinella nutti (you can measure growth bands in them, much like tree rings) collected by many expeditions from Scott to modern times and found, as the diagram shows, a much increased growth rate as of the 1990s. This is attributed to phytoplankton blooms leading to nannoplankton increase, which the bryozoans feed on, leading to higher growth rates.
Obviously, anthropogenic climate change caused by excessive greenhouse gas emissions is a huge problem and we need to urgently find solutions to it. One possible pathway is for planet-scale solutions referred to as geoengineering. This paper reviews the different schemes that have been proposed over the years, highlighting especially their feasibility – after all, anyone can think up of ideas, but if they’re too expensive or just batshit insane, they won’t be implemented.
11. Climate Change-Driven Microevolution
Everyone who’s had a single evolution lesson in high school knows about the peppered moth as an excellent example of natural selection: in pre-industrial England, the whiter variants of the moth were selected for as they blended in well with the lichens on tree barks, so they were eaten less by predators; after the industrial revolution, the darker variants were more popular since the tree barks were stained by pollution, and the whiter variants stick out too much and thus are eaten more by predators. I bring this up because it’s a great parallel to the situation in this research: both are examples of crucial evolutionary processes and both have humans as their primary cause. In this case, we’re dealing with tawny owls. They have a brown and a white colour morph, and these colours, as shown in the diagram, are genetically coded for (you can use it as a standard example for Mendelian genetics too!). The brown morphs in the past 50 years have shown a marked decline in population numbers – this is concurrent with the increase in anthropogenic climate change-caused harsher winters. So climate change is driving natural selection on a heritable trait and affecting microevolution. (The reason, however, is not as simple as brown sticks out more in the snow; it could also be that increased melanism causing the brown colouration requires more energy, leading to more foraging and thus an increased predation risk.)
12. Spider Webs
Proper study of spider webs must be done with many factors taken in consideration: taxonomy, feeding ecology of the spider, location of the web, competition between individuals, ecophysiology, removal of webs, sexual behaviour, vibration transmission, neurobiology, attacking behaviour, communication, energetics, timing and phenology, web construction cues, structure of webbing lines, composition and physical properties of the silk, structure of the silk glands, etc. This is what this paper emphasises: in order to properly understand spider webs, we have to look at the whole picture instead of drawing (adaptive) conclusions from only one factor, no matter how spectacular that one factor is.
13. Adaptation to Climate Change
Climate change and its effects on evolution pop up again. This paper is a review of the potential for climate change to drive large scale evolutionary adaptations. We have very good reason to consider this as a possibility. For example, the geographical distribution of ectotherms is very well correlated with latitudinal and other temperature gradients. Species have differing thermal tolerances (e.g. ants eggs don’t hatch at temperatures below 20°C, but ant adults will dessicate if placed in 40°C for too long). These tolerances are physiological, so that’s where natural selection will be acting, keeping in mind the potential of phenotypic plasticity. For those populations where extinction is a real risk, can evolution occur fast enough to save them by modifying their tolerance thresholds? These are all valid questions that directly impact how we consider evolution under a global climate change scenario. Read this paper if this topic is interesting to you.
14. New Lobopod
Lobopods are of intense interest to anyone who’s into early arthropod evolution in the Cambrian. The first described lobopod was Aysheia pedunculata from the Burgess Shale, followed by Hallucigenia sparsa, also from Burgess. Then came a slate of new discoveries from China, with Microdictyon sinicum, Luolishania longicruris, Onychodictyon ferox, Cardiodictyon catenulum, Hallucigenia fortis and Paucipodia inermis. Add to those four other species from northern Europe and Greenland: Xenusion auerswaldae, Pambdelurion whittingtoni, Kerygmachela kierkegaardi and Hadranax augustus. These have all been recognised as being closely-related to each other, as well as being rather similar to the arthropods (sensu lato to include the tardigrades and onychophorans). This century, three new finds from China have reinforced this link: Miraluolishania haikouensis, Jianshanopodia decora and Megadictyon cf. haikouensis. They are more derived and can be seen as being mosaics of lobopodan and arthropodan features. Being stem-group organisms, it’s obvious that lobopods are paraphyletic. This conclusion is supported by the lobopod newly described in this paper. It has several other exciting features, but since I promised to not write anything on arthropod evolution – unless requested – I will not go into more detail.
15. Climate Change and Extinction
Sick of climate change yet? This paper presents the possibilities of extinction in Europe due to climate change. The methods are supremely interesting and the results are depressing (see the third column in the picture above; PD is phylogenetic diversity).
16. Olfactory Learning in Terrestrial Snails
The picture shows a dissected CNS of a slug, including the tentacles up there. Snails are model organisms for research in olfactory learning. Like mammals and arthropods, their olfactory nervous systems consist of many small neurons (in contrast to other neurons, which are relatively large). This small size is the only stumbling block in research using them; otherwise they are ideal. Snail eyes can’t form images and they can’t perceive sounds, so smelling is the only way they can perceive long-distance stimuli, including food and conspecific location and navigational clues. The organs used for olfaction are at the tips of the tentacles; terrestrial snails have for tentacles, all more or less identical. From the organs, they have an olfactory pathway consisting of the tentacular epithelium and the subepithlial glomeruli, the tentacular ganglion and the procerebral region of the brain. There are, on average, 100000 sensory neurons and 25000 interneurons involved – contrast this with the rest of the CNS consisting of 25000 neurons. If I have piqued your interest in snails and their sense of smell, read this paper.
17. Flight Muscle Physiology
I introduced insect flight muscles in this post. This paper adds a bit to our knowledge of how they work by finding that there is a temperature gradient formed in different regions of the muscles. This obviously has functional implications, as muscle activity is strongly affected and controlled by temperature.
18. Ocelli Used for Polarisation Vision
I already spoke of how ants use polarisation patterns in the sky as navigational guides in this post. This paper adds to our knowledge of this by finding that in this desert ant species, the ocelli function in detecting these patterns in the sky.
19. Non-Wetting Insect Cuticle
The picture shows a drop of water on the wing and leg of a cranefly. As you can see, the cuticle is completely impermeable to water, or superhydrophobic. This is a property found in many/most insects; I already mentioned that damselfly wings are impermeable to water; water striders can walk on water because of many tiny setae on their legs that trap air; the cicada wing membrane has a chemical composition that makes it impermeable. And so on. Studying these is of interest, of course, for engineering and nanotechnology, as the solutions found by insects can be mimicked to produce materials that are waterproof. Now they have one extra insect they can look to for inspiration: the cranefly has specially arranged setae and grooves in its cuticle that doesn’t allow it to become wet.
20. Burrowing Polychaete
I didn’t mention the glycerids in my annelid systematics post. They’re polychaetes that burrow in the mud. This paper shows us how: it uses its proboscis (the extended part in the middle pictures) to make cracks and then wedges them open.
21. Effect of Weather on Orthoptera
In arid environments, like the one studied in this paper (Algeria), rainfall is the largest limiting factor on grasshopper populations. Populations will often migrate to areas where rainfall is occurring (they feed on plants, so where there is rain, there is food). This paper attempts to quantify exactly which abiotic factors affect orthopteran (grasshopper, bushcricket, locusts et al.) populations in arid environments and how. This is obviously important for predicting the behaviour of pest species which can be extremely destructive to crops (think of locust migrations).
22. Changes in Diet During Human Evolution
Bipedalism is not the only important feature that got selected for in human evolution. Apes started walking to different places to get food. What sort of food? The fossil record provides evidence for changes in nutrition during the evolution of humans (e.g. picture above). This paper reviews these changes, but also from a modern genomic point of view, including how we can detect them with genomics.
23. Chemical Communication Evolution
Everyone’s heard of pheromones. They’re chemicals used for many purposes: there are sex pheromones that attract mates, trail pheromones I mentioned above, deceptive pheromones that cloak an animal’s scent to allow them to blend within a colony (used by parasites), etc. They often have different purposes depending on what individual detects them: some pheromones attract females but repel males. Some are detectable only by specific individuals. The diversity of pheromonal interactions is large enough to merit its own field of study, chemical ecology. This paper proposes an all-encompassing view of the evolution of chemical communication, but not only focussing on pheromones. It discusses how originally, these chemical cues are released by accident but seemingly have a positive effect and are kept by natural selection – it’s quite a dynamic hypothesi, but it makes sense considering how multi-functional pheromones and their allied chemicals are.
24. Morphological Stasis
The picture shows a tree with divergence dates for two fish species calculated using two molecular clock models. Regardless of which one is correct (the answer lies in geology), the date is sometime between 57 and 88 Ma. Despite all this time available for macroevolution, the fish species look exactly the same. This is extremely interesting for those of us interested in the tempo and mode of evolution. There are several hypotheses available to explain this; the one that’s most likely, in my opinion, is phylogenetic niche conservatism, i.e. that the two fish species have the same ecological role and thus have retained the same morphology because it works.
25. Archaean and Eukaryotic Origins
Archaeans are immediately recognisable as extremophiles: the three traditionally recognised groupings are methanogens, haloaechaea (halophiles, live in the Dead Sea and other extremely salty environments) and thermoacidophiles (live in hot places like volcanic marine and terrestiral volcanic fields). They’re the only organisms capable of producing methane by methanogenesis (taking methyls and converting them to methane). Another characteristic trait is their lipid strucutre, consisting of ether-linked isoprenoids with a glycerol-1-phosphate backbone. However, they also share several characters with the eukaryotes (DNA replication, transcription and translation) and the bacteria (metabolism). So they are overall very interesting and critical for understanding early microbial evolution (hence why the astrobiologists are obsessed with them). The origin of the eukaryotes is not as critical for the origin of life, but is an interesting question in itself. This paper uses phylogenetics to answer the origins question. The researchers find that the methanogens are the more ancestral archaeans – therefore hinting that methanogenesis was the original metabolic pathway. As for the eukaryotes, the implications of their findings are that the archaeans are actually a paraphyletic group and that eukaryotes are nothing more than derived archaeans; specifically they are either the sister group to the Thaumarchaea or derived Thaumarchaea.
26. Dinosaur Origins
Before this paper, we thought that dinosaurs originated in the last 30 Ma of the Triassic. They were rare back then, with only 30 out of a total of 500-700 genera present. They were relatively small, the largest predator being 4m long and the largest plant eater 3 tons. Most of them were omnivorous. Anyway, this paper describes footprints that extend the known dinosaur fossil record by 20 Ma. The implications are that there was a 50 Ma period where dinosaurs were minor components of the fauna – they only became to prominence later in the Jurassic. This, of course, demands an explanation. (The answer probably has something to do with the crocodiles and their crurotarsan relatives being more dominant back then, before an extinction event at the end of the Triassic wiped out all but the crocodiles and allowed the dinosaurs to take over.)
27. Egg Size and Sex
I’ve mentioned haplodiploidy in multiple articles, notably in the parthenogenesis post. This paper adds a twist to the story finding that in the spider mite, egg size is another factor contributing to whether the resulting adult is male or female. Although I have to say, egg size may not be a factor but an effect – males are smaller, so the eggs are naturally smaller. In other words, correlation is not causation.
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This issue of the Journal of Orthoptera Research (V.19(2)) is partly dedicated to research into orthopteran chromosomes and the legacy of Michael White, the most prominent orthopteran cytogeneticists. This field has an extensive history and findings from it, especially from Michael White’s work, were essential to the development of the chromosome theory. Because they’re all review papers, I won’t be writing commentaries on each one. The titles are pretty self-explanatory. Check out the Table of Contents!
28. Hisorical Overview
This is the paper reviewing the history of chromosome research using orthopterans and Michael White’s contributions.
29. Michael White
Biography of Michael White.
30. Orthopteran Sex Chromosomes
A review of orthopteran sex chromosomes (they’re pretty unique!).
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31. Human Effects on Biodiversity
The most noticeable effect that humans have on the environment is through the modification of land to agriculture and urbanisation. This obviously has drastic effects on the local populations. This paper quantifies how orthopterans react to the changes.
32. New Melanoplus
It’s not all death and destruction though. Here’s a new grasshopper species, Melanoplus ingrami!
33. Gryllotalpidae Molecular Phylogeny
The Gryllotalpidae are the mole crickets. They’re found in temperate and tropical regions and are well-known for their digging forelimbs and singing; also known from them is maternal care. Species numbers range from 46 to 78. They’re a bit of a special group in that genera exhibit unique behaviours and there is the possibility of using these as an extra source of data for reconstructing the family’s phylogeny. Anyway, this paper instead does molecular phylogeny based on a way-too-poor taxon sampling.
34. Eumastacids in Madagascar and the Seychelles
This must be one of the shortest papers I’ve ever read. It’s a note on how the eumastacids could have gotten on to those islands.
35. Oecanthus rileyi species-group
A taxonomic note and description of a new species.
36. Grasshopper Necrophagy
The picture shows a female Taeniopoda eques feeding on dried meat from a coyote carcass. This isn’t surprising: grasshoppers are primarily herbivores, but when in need, they will go for meat. It’s rare, but observeable.
This is a systematic review of Megacrania, a stick insect genus, in Malo, New Hebrides. It also includes a helpful key.
38. Homoplasy Detection
A homoplasy is a feature that arises through convergent evolution acting on an ancestral, homologous trait. This is not to be confused with an analogue, which is a feature that arises by convergent evolution on non-homologous traits. This paper goes through how we can identify homoplasies – it’s easy to mistake a homoplasy as being the actual ancestral condition rather than a result of convergence.
39. Fire Ant Invasion History
The fire ant Solenopsis invicta is something of an expert at invading foreign territories, having become widespread especially in America, even though it didn’t originate there. This paper reviews its biogeographical history – the methods are quite cool.
40. Larval Silkworm Mouthpart Sensillae
One of the most striking things about insects is how detailed their structures are down to a microscopic level. The pictures in this paper are proof of that: it examines the morphology of structures on the hairs that cover the mouthparts of the larva of a silkworm species. Awesome.
41. Flu Vaccine Production
For the German speakers, this paper goes through the steps involved in thinking up, developping, testing and releasing a flu vaccine. Quite useful for us Big Pharma minions.
42. Trichinella spiralis Genome
If you feel like shitting yourself, read up on what Trichinella spiralis can do to you, then bathe yourself in chlorine [Author's Note: This is not a medical blog. Please consult your doctor before attempting anything read in this paragraph]. Its genome is reported in this paper, which should hopefully help us in making drugs to kill the fuckers before I have to suffer any tiny bit of pain.
43. Ice Age Temperatures
We’re at 115000-74000 years before present, in an interglacial stage when it was warmer and the ice caps weren’t all over Europe. Humans were busy taking over the world and Neandertals expanded into Central Europe. This paper gives us an average air temperature for the time.
44. Human Evolution in South Africa
Some more modern human evolution. This paper examines how Pliocene evolution in humans proceeded in South Africa in relation climatic changes. I can’t comment much because human evolution bores me.
45. Mammoths in Europe During the Last Glaciation
Since the primary purpose of this blog section is to merely alert readers to the research published, I don’t actually feel obliged to write commentaries on the papers, especially those tht I personally have no interest in and only include because they may be of popular interest.
46. Evolution of Mediterranean Ecosystems
For the French readers interested in historical ecology of the Mediterranean, this paper presents a pollen analysis from the southwest Mediterranean (Spain and North Africa) from the Plio-Pleistocene. By analysing the pollen remains, we can tell what plants were around; by drawing analogues with modern ecosystems, we can tell what the climate was like. It’s basic palynology.
47. Earliest Triassic Molluscs
The extinction at the end of the Permian was the most severe in the history of life on Earth, occurring very abruptly. The causes are still disputed but include asteroid impacts, massive volcanism or extreme sea-level rise leading to widespread anoxia. Regardless of the cause, the fossil record has shown that recovery in the Triassic was rather gradual. The locality and fauna described in this paper stands in stark contrast to that, showing that at least benthic life had recovered pretty quickly.
48. Ants and their Parasites
Being the most successful animals around, ants have their share of mimics and parasites, for example the staphylinids in the picture above. They often have many parasites at once. Because of this, ants are ideal for studying the ecological and evolutionary consequences of parasitism. This paper contributes by quantifying the defensive reaction by army ants to different parasites. The more harmful the parasite, the more lethal the reaction.
49. Male Opilionid Sexual Dimorphism
Spiders are renowned for wacky sexual behaviours, for example post-coitus cannibalism. Like in the dung beetles (#2), males can also be dimorphic with a major and minor form. This is the case in the species studied in this paper, Serracutisoma proximum. The point of the paper was to determine what causes the different phenotypes to emerge. Unlike in the dung beetles, where the morphs are genetically determined, in the harvestmen it seems to be environmental, depending on the season and on the relative presence of the morphs.
50. Earwig Male Genital Evolution
Similar to the dung beetles (#2), this paper find heritable variation in male genital morphologies. (I don’t think I really need to write about sexual selection, do I?)
51. Temperature Effect on Springtail Life History
Another paper to add to the effect-of-climate-change-on-organisms collection. This time, how temperature affects Orchesella cincta, a collembolan, in terms of several life history traits. The implications are significant, since collembolans are some of the most important components of the soil fauna, along with mites. They’re found in all ecosystems from hot deserts to arctic tundra to tropical rainforests, where they can assemble to densities of millions of individuals per m². In a single habitat, up to 60 species may be present. So studying how abiotic factors influence them is of paramount importance to predicting the changes that global warming will bring about.
52. Grasshopper Colour Polymorphism
The picture above shows two individuals of the same grasshopper species, Acrida ungarica. However, one of them is brown and the other is green. These two colour morphs are seasonal, related to the grasshopper’s phenology: int he dry season, the brown form is present as it fits in with the dry grass, in the wet season, the green form predominates as it fits in with the green plants.
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This week’s issue of Brain Research (V.1380) is devoted to autism. Since these are all reviews, I won’t comment much on them and the titles are pretty self-explanatory. Visit the Table of Contents to see all the articles, as my interests are pretty limited.
53. Autism Research
This paper discusses just what autism research entails.
54. Autism and Intelligence
A common pop-psychology myth is that all autists are super-geniuses. Like all of pop-psychology, this is mere baseless stereotyping. This paper deals with the intelligence – in the sense of cognition – of autists.
55. Adult Autism
Another common miscocneption is that autistic kids can “grow out of it”. This is an endless source of frustration for autistic adults, or so I’m told. This paper deals with autism in adults.
56. Schizophrenia and Autism
I’ll admit, I’d never heard of a link between schizophrenia and autism, but apparently it has been suggested that schizophrenia is a disorder on the autism spectrum. This paper discusses the link, finding that there is in some respects considerable overlap in the pathologies, so while schizophrenia is not an autistic disorder (nor is autism a schizophreniax disorder), studying them together could lead to new insights.
57. Autistic Brain Growth Patterns
The most interesting paper in my opinion: how brain growth in autists differs from non-autistic brain growth.
58. fMRI in Autism Research
Everyone knows fMRIs, the scans that tell us what brain regions are activated (and the source of much pop-psychology bullshit, incidentally). This paper discusses the uses and pitfalls of using fMRIs in studying the responses of autistic people.
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59. Regulation of C4 Photosynthesis
The majority of flowering plants undergo C3 photosynthesis, in which the three-carbon compound (hence C3) phosphoglyceric acid is produced after the action of RuBisCo. However, there exists a minority in which phosphoenolpyruvate carboxylase is used to fix HCO3- into the four-carbon compound (hence C4) oxaloacetic acid instead. Despite their taxonomic minority, these plants are overall the most important from our point of view, as the most agriculturally significant crops are C4 plants. This paper reviews how this pathway is regulated at a molecular level.
60. The Ecosystem Concept
“Ecosystem” is probably one of the most used words in biology. Yet if someone asked me for a definition, I would be stumped and it would be pretty embarassing. The concept of the ecosystem, while not vague per se, is all-encompassing and can refer to anything from an amalgam of habitats to population mixtures to even social ecosystems. This paper reviews the entire concept of the ecosystem.
61. Wing Shape in Mepraia
Mepraia is a member of the triatomine subfamily, a group characterised by blood-feeding. They’re well-known due to medical entomology, as they’re vectors for Trypanosoma cruzi, the parasite causing Chagas disease. Chagas disease, for those who don’t know, infects over 9 million people in tropical-subtropical America, with an additional 40 million people at risk of infection. As such, proper vector species identification is of paramount importance in this region. Of course, doctors aren’t trained in taxonomy and species identification. This paper provides an easy way to do identify two of the common Costa Rican Mepraia species by measuring wing shapes alone – the two species are cut into two neat groups corresponding to the two species, and it’s easy enough for even a doctor to get the species right.
62. Termite Trail-Following Gene
In eusocial insects, behaviour often has a strong genetic basis. This paper links the expression of a specific gene, deviate, to the activity of the termite Reticulitermes flavipes. The main finding is that it encodes a protein involved in perceiving trail pheromones and potentially controlling circadian rhythms or locomotion.
63. Fossils in Phylogenetics
I have held several talks and written even more essays on this subject. This isn’t really a peper, more of a commentary. Read it if you’re interested. I may do a post on it some time if requested.
64. Onion Thrips
Thrips tabaci, the onion thrips, is a huge pest that has developped insecticide resistance. This paper reviews all about it (but doesn’t even bother to include a morphological diagram for identification, but whatever) and what we can do to control its population.
65. Leaf-Cutting Ant Genome
Atta, the most abundant attine (leaf-cutting) ant genus, is restricted to the New World, where it is one of the most significant herbivores, its effects being felt even at the forest composition and structure level. They’re well-known for their fungus agriculture. The leaves the cut are used to feed the fungi in the nests; the fungi are the food source for the larvae (the workers feed on sap obtained during cutting). The genome of the most common one, Atta cephalotes, has now been sequenced, presumably because leaf-cutting ants are cool. You know what I’m going to say here: this genome will give us important clues and insights to the evolution of eusociality, etc., etc., etc.