Imagine you drive into a motel in Gatlinburg TN, and see behind an open room door 2 guys setting up cameras pointing at the beds while two young women peek from the parking lot. Well, if it was in the mid ’90′s it might have been Drs Moiseff and Copeland setting up the equipment before [...]... Read more »
Moiseff, A., & Copeland, J. (2010) Firefly Synchrony: A Behavioral Strategy to Minimize Visual Clutter. Science, 329(5988), 181-181. DOI: 10.1126/science.1190421
Every now and then, I come across a study that makes me hope my first doubtful impression is wrong and that the authors have better evidence to back up their claims. One such case was the hypothesis that the feathered dinosaur Sinornithosaurus had a venomous bite, as was proposed by scientists Enpu Gong, Larry Martin, [...]... Read more »
Gianechini, F., Agnolín, F., & Ezcurra, M. (2010) A reassessment of the purported venom delivery system of the bird-like raptor Sinornithosaurus. Paläontologische Zeitschrift. DOI: 10.1007/s12542-010-0074-9
The electrical symphony of the human brain, with billions of neurons firing at different rates, up to hundreds of times per second, likely looks like chaos to any outside observer. But there are patterns in the ongoing brain activity seen, for instance, on an EEG: slow oscillations, rhythmic coordination, and purposeful ripples of communication. The [...]... Read more »
Distinguishing your own species from other species is useful: for one thing, it prevents a lot of potentially embarrassing mating attempts.
“Um. You mean we don’t belong to, er... that is to say... you’re not my species? I am so sorry...”
But how fine a distinction can a species draw? Does it stop at, “You’re not my species,” or can it extend to, “You’re species B, not C or D”? And would species be able to distinguish other species outside of reproduction?
Schuchmann and Siemers tackled these questions by studying the echolocation calls of several related bat species that live in Europe.
Bats use echolocation for, well, location. They are not used in situations where animals are interacting with each other: they are used purely for the bat to get from point A to B without running into trees, and to find food. Even so, the sound that each bat species makes tend to be a little different in pitch. Might one bat species go, “That call is a bit to high to be Rhinolophus euryale, might be Rhinolophus ferrumequinum.”
These, I thought, were very interesting questions. But it wasn’t clear to me how they were going to test it.
The experimental set-up they use reminded me of one that is often used to test the cognitive abilities of babies. Bats, like babies, are easily bored. If you keep presenting the same thing over and over, they stop looking at it. When they detect a change, they react and look towards the new and much more interesting stimulus.
They recorded the echolocation calls of four bat species, and played them back to two (one of them, Rhinolophus euryale, pictured). They kept playing the same call from their own species over and over until the bat stopped responding, then swapped it for a new call.
Bats were very good at detecting when the call switched from their own species to a different species. That isn’t surprising, as it just tells you they can recognize their own species’ calls.
More to the point, when they first habituated the bat to a species different than themselves, and switched the call to yet a third species... the bats were still very good at detecting that difference. So the bats are not reacting with, “Meh. All those other species’ calls all sound alike. Not my species, have a nice day.”
It’s not clear what components of the call the bats are recognizing, although pitch is probably the major one. You could probably do some fun experiments seeing how much you could vary the calls and still have the bats responding. The authors also wonder if these different species might be able to benefit by eavesdropping on other species’s calls. If so, there might be some species that are more worth listening to at some times than others.
P.S. – Dart to the authors for using so many two letter abbreviations for species (Re) instead of writing out species names properly (Rhinolophus euryale)!
Schuchmann M & Siemers B. 2010. Behavioral evidence for community‐wide species discrimination from echolocation calls in bats The American Naturalist 176(1): 72-82. DOI: 10.1086/652993
Photo by by jasja dekker on Flickr. Used under a Creative Commons license.... Read more »
Schuchmann M, & Siemers B. (2010) Behavioral evidence for community‐wide species discrimination from echolocation calls in bats. The American Naturalist, 176(1), 72-82. DOI: 10.1086/652993
... Read more »
Braunisch, V., Patthey, P., & Arlettaz, R. (2010) Spatially explicit modelling of conflict zones between wildlife and outdoor snow-sports: prioritizing areas for winter refuges. Ecological Applications, 2147483647. DOI: 10.1890/09-2167.1
This amazing movie, from Niethammer P, Grabher C, Look AT, Mitchison TJ. 2009 A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafish. Nature 459 996-9 PMCID: PMC2803098, shows leukocytes (the white blobs) rushing to the site of a wound in response to a hydrogen peroxide signal (fluorescence in upper panel).
We’ve known for a while that leukocytes rapidly (within minutes) home to the sites of wounds. What hasn’t been clear is what signal attracts them. We’ve also known for a while that hydrogen peroxide is generated in wound sites: but until now, the general belief has been that it comes from the leukocytes that are attracted into the wound. Hydrogen peroxide has a role in killing bacteria, at least under some conditions, and so this all seemed to make sense. Until this movie. ... Read more »
Niethammer, P., Grabher, C., Look, A., & Mitchison, T. (2009) A tissue-scale gradient of hydrogen peroxide mediates rapid wound detection in zebrafish. Nature, 459(7249), 996-999. DOI: 10.1038/nature08119
Today's post is some seriously OLD science. Old science and WEIRD science, coming to you courtesy of Mt. Sinai hospital in NYC, 1913.
And it's also the WEIRDEST conjunction of this:
That Sci has ever seen.
Gerster AG, Mandlebaum FS. "XI. On the Formation of Bone in the Human Penis." Annals of Surgery, 1913.
The pictures below are curiously safe for work. I suppose that picture up there wasn't. oops. Read the rest of this post... | Read the comments on this post...... Read more »
Today’s post is some seriously OLD science. Old science and WEIRD science, coming to you courtesy of Mt. Sinai hospital in NYC, 1913. And it’s also the WEIRDEST conjunction of this: And this: That Sci has ever seen. Gerster AG, Mandlebaum FS. “XI. On the Formation of Bone in the Human Penis.” Annals of Surgery, [...]... Read more »
A coding-independent function of gene and pseudogene mRNAs regulates tumour biology Laura Poliseno, Leonardo Salmena, Jiangwen Zhang, Brett Carver, William J. Haveman & Pier Paolo Pandolfi Nature 465: 1033–1038, 24 June 2010. doi:10.1038/nature09144 No formal write-up for this week, rather just some points to consider, raised during our journal club discussion: The authors’ probing of [...]... Read more »
Poliseno L, Salmena L, Zhang J, Carver B, Haveman WJ, & Pandolfi PP. (2010) A coding-independent function of gene and pseudogene mRNAs regulates tumour biology. Nature, 465(7301), 1033-8. PMID: 20577206
Immunosenescence is the steady degeneration of the immune system that occurs with age. For the adaptive immune system at least, researchers have a good picture as to why and how this happens - which means that they also have starting points to develop ways to reverse immunosenescence. Here is an open access review paper on the topic: The elderly frequently suffer from severe infections. Vaccination could protect them against several infectious diseases, but it can be effective only if cells that are capable of responding are still present in the repertoire. Recent vaccination strategies in the elderly might achieve low effectiveness due to age-related immune impairment. ... Ageing dampens the ability of B cells to produce antibodies against novel antigens. Exhausted memory B lymphocyte subsets replace naive cells. Decline of cell-mediated immunity is the consequence of multiple changes, including thymic atrophy, reduced output of new T lymphocytes, accumulation of anergic memory cells, and deficiencies in cytokines production. Persistent viral and parasitic infections contribute to the loss of immunosurveillance and premature exhaustion of T cells. In essence, the immune system fails because the thymus, source of immune cells, ceases production and withers away. At the same time, the population of immune...... Read more »
Ongrádi, J., & Kövesdi, V. (2010) Factors that may impact on immunosenescence: an appraisal. Immunity , 7(1), 7. DOI: 10.1186/1742-4933-7-7
The abundance of large mammals in Africa’s protected areas has dropped by more than half since 1970, scientists say.
The findings, reported in Biological Conservation, emerged from an analysis of 69 species in 78 protected areas. The team scoured studies, databases, and reports for data on mammal populations and calculated that abundance had decreased by […] Read More »... Read more »
Craigie, I.D. et al. (2010) Large mammal population declines in Africa’s protected areas. Biological Conservation. DOI: 10.1016/j.biocon.2010.06.007
Endangered right whales in the Atlantic Ocean are turning up the volume of their calls as their environment becomes more cacophonous, according to a report in Biology Letters.
North Atlantic right whales (Eubalaena glacialis) call to each other at a frequency of about 50 to 400 Hz. Many of the animals live in an area […] Read More »... Read more »
Parks, S.E., Johnson, M., Nowacek, D., & P.L. Tyack. (2010) Individual right whales call louder in increased environmental noise. Biology Letters. DOI: 10.1098/rsbl.2010.0451
Keeping with the theme of sensory systems, I thought I'd review some newer research on squids.While searching for recent cephalopod neurobehavioral research (which is pretty scant) to blog about, I came upon Makino and Miyazaki's study on the distribution of retinal cells in the retina of squids. I have a soft spot for visual neuroscience that I picked up from working with my first research advisor, who works on the visual system of frogs. In any case, this is a good paper (although it was a bit hard to get my hand on,) and I'll review it here.The study aims to look at the distribution of retinal cells in the retinas of a variety of squid species. This has been done in several vertebrates, with the general finding that animals have retinas that perform well for their lifestyle. Seems pretty simple, right? For example, fish who live in "closed" environments have dense retinal ganglion cells (RGCs) in the area of the retina that sees light from directly ahead, while oceanic fish have a strip of high-density RGCs that stretch laterally across the whole visual field. Thus (to make a horribly crude generalization,) cave and reef dwelling fish have focused binocular vision, while oceanic fish largely lack this but have a greater ability to monitor their whole visual field, ie. for predators or food items.In vertebrates, retinal ganglion cells are often mapped in this sort of study. By the time RGCs exit the retina, they are carrying visual information that is already processed into the very basic components of visual perception (namely, hue and tone contrast.) As vertebrates have complex retinas, it is also possible to map photoreceptors in vertebrate retina, or a variety of other types of cells (which might be more or less informative.) Cephalopods, however, only have one type of visual cell in their retina - the retinal cell (or rhabdomere.) So, the authors chose to map this. It is useful to keep in mind that this is not directly comparable to the mapping of retinal ganglion cells in vertebrates - it could be the case that the density of visual cells in an animal's retina is not always correlated with the importance of that piece of the visual field in further levels of visual processing. This problem is partially solved in studies on vertebrates by the use of RGCs, in which the processing of information from photoreceptors is already underway. With cephalopods, however, there is currently no way to probe this any deeper, and so for now it remains an assumption - albeit a pretty noncontroversial one - that rhabdomere density is correlated well with the relative importance (behaviorally and neurophysiologically) of portions of the visual field. (For more on cephalopod visual anatomy, check out my earlier post on cephalopod eyes.)The image to the left shows cell counts (in retinal cells per mm) across the retinas of the 5 species of squid. I added color to this image to make it easier to see the distribution of cells. It's important to not that the colors are relative within each figure, and do not represent absolute cell density, which is shown as (difficult to read) numbers on the boundaries of regions. Also note the scale bars, which are 10mm in every image. In terms of orientation, keeping things straight gets a little tricky (as it does with all cephalopods.) Dorsal-ventral orientation is pretty easy - remember that the lens of the eye inverts the light coming through it, so that the ventral part of the retina forms the top part of the visual field and the dorsal part of the retina forms the bottom part of the visual field. Anterior is the direction the squids' arms point in, so the anterior retina forms the posterior part of the visual field. The posterior retina is the part that forms the anterior part of the visual field. This is the part that is used when squids look forward to form a binocular image.Using this data, the authors estimated the visual axes of the squids, based on the location of the highest density of photoreceptors. The visual axis is the general point of focus, which is known to be of utmost behavioral importance in vertebrates. When you follow a moving object with your eyes, you are keeping it in your visual axis. The location of an animal's visual axis is key to its visual ecology - many predators have forward facing visual axes so that they can see their prey accurately, while prey species often have very laterally oriented visual axes (think of rabbits and deer) so that they can monitor more of their environment at any given time. Thus, we'd expect that squids with different lifestyles have different visual axes, because they will be looking for food and predators in different places.In coastal squid (E. morsei and S. lessoniana), the visual axis is directed downwards, presumably reflecting the importance of monitoring activity on the substrate that these species live on. In oceanic squid (T. pacificus, E. luminosa, and T. rhombus,) the visual axis is directed upwards, and the eyes have a much greater density of photoreceptors overall. I think the retinal cell density map of E. luminosa is especially interesting, because the concentration of cells on the extreme posterior edge of the retina suggests that binocular vision is disproportionately important to this species. The authors conjecture that this eye may be specialized to detect and track bioluminescence in the open ocean, but this is purely speculation.These findings are important because they expand our knowledge of cephalopod eyes, which are a model evolutionary system. If we can begin understand the impact of ecology on the organization of visual systems (which is part of the emerging field of visual ecology,) we can generate a wealth of testable hypotheses about the ecological conditions that occurred during the evolution of differnt species eyes, as well as the other sorts of adaptations we might see in sensory systems as they diverge (or converge) during evolution. It's also a nice piece of evidence that our rather basic theories about visual ecology and the structure-function relationship of the visual system are largely correct. This is good to know, as we base an incredible amount of more complicated neuroscience research on these theories.Thanks for reading!Akihiko Makino, & Taeko Miyazaki (2010). Topographical distribution of visual cell nuclei in the retina in relation to the habitat of five species of decapodiformes (Cephalopoda) Journal of Mulluscan Studies, 76, 180-185 : 10.1093/mollus/eyp055... Read more »
Akihiko Makino, & Taeko Miyazaki. (2010) Topographical distribution of visual cell nuclei in the retina in relation to the habitat of five species of decapodiformes (Cephalopoda). Journal of Mulluscan Studies, 180-185. info:/10.1093/mollus/eyp055
When most people hear the word “wolf,” they think of the burly gray wolves of the Great White North. But wolves are present all over the world, even in Africa. The Ethiopian wolf, Canis simensisis incredibly endangered. As its name implies, it lives in Ethiopia, but it lives only in seven highland mountain ranges, above [...]... Read more »
Randall, D., Pollinger, J., Argaw, K., Macdonald, D., & Wayne, R. (2009) Fine-scale genetic structure in Ethiopian wolves imposed by sociality, migration, and population bottlenecks. Conservation Genetics, 11(1), 89-101. DOI: 10.1007/s10592-009-0005-z
Fossil dinosaur tracks don’t often get the same popular attention that skeletons do. The impressions within the rock seem to pale in comparison to the beautiful organic architecture of the bones, but, while they might not be as aesthetically interesting to some, tracks are bits of behavior preserved for millions of years. They were made [...]... Read more »
Kim, B., & Huh, M. (2010) Analysis of the acceleration phase of a theropod dinosaur based on a Cretaceous trackway from Korea. Palaeogeography, Palaeoclimatology, Palaeoecology, 293(1-2), 1-8. DOI: 10.1016/j.palaeo.2010.04.020
If you work on plants and you've extracted DNA from them in the last 20 years, chances are that you've used some version of the method described by Doyle and Doyle.1 According to Google Scholar, Doyle and Doyle has been...... Read more »
Bellstedt, D., Pirie, M., Visser, J., de Villiers, M., & Gehrke, B. (2010) A rapid and inexpensive method for the direct PCR amplification of DNA from plants. American Journal of Botany. DOI: 10.3732/ajb.1000181
African rift lake cichlids are among the most famous subjects for the study of evolution. The rift lakes formed recently in geological time, but the cichlids that got in have radiated into a dazzling array of species in short order.
But there are cichlids and other similar recent geological events in the Americas, too, just as interesting!
This research by Elmer and colleagues takes advantage of a lake made by volcanic activity, in Nicaragua. The lake appears to have been formed about 1,800 years ago.
View Larger Map
This crater lake has been colonized by Midas cichlids and a few other fishes. The researchers have done a lot of DNA work here, and based on it, they think the Midas cichlids only got into the lake in the last hundred years or so. This population differs in several respects from the cichlids in the nearest neighbouring lakes.
There are two types of Midas cichlids in this lake: there's a common thin-lipped type (pretty sure this is what's pictured here), and a rarer thick lipped type. This difference in appearance is correlated with diet: the common thin-lipped guys have algae, fish and snails in their stomachs, while the thick-lipped one have arthropods.
Elmer and company argue that this could be a case of incipient speciation here. This is an attractive possibility, given that they seem to have two morphs that have different diets, which could leads to different ecological niches, which could lead to reproductive isolation. While plausible, they could not find any genetic distinction between the nuclear or mitochondrial genes between the two morphs (though they commit the crime of "but it's almost significant" for the mitochondrial DNA).
What needs to happen next? Someone needs to make this lake the focus of a career, and start documenting the populations year in, year out, much like Peter and Rosemary Grant did for the Galapagos finches. There need to be behavioural tests to see if fat-lipped females like fat-lipped males more than thin-lipped ones. There need to be ecological studies to see if these animals are inhabiting different locations in the lake.
If this population truly is this young, we have a great chance to watch speciation happen in front of our eyes.
Elmer, K., Lehtonen, T., Kautt, A., Harrod, C., & Meyer, A. (2010). Rapid sympatric ecological differentiation of crater lake cichlid fishes within historic times BMC Biology, 8 (1) DOI: 10.1186/1741-7007-8-60
Midas cichlid picture by Just Chaos on Flickr. Used under a Creative Commons license.... Read more »
Elmer, K., Lehtonen, T., Kautt, A., Harrod, C., & Meyer, A. (2010) Rapid sympatric ecological differentiation of crater lake cichlid fishes within historic times. BMC Biology, 8(1), 60. DOI: 10.1186/1741-7007-8-60
One article I did take the time to read, though, is Race, Sex and the Regulation of Urine Osmolality-Observations Made During Water Deprivation by Hancock et al. Hancock and colleagues got an almost equal mix of white and black men and women to agree to 24 hours of water deprivation, during which time they measured urine and plasma osmolality, vasopressin levels, urine volume, and a few other things. I read it, and it had me thinking some thinky thoughts, so I figured I’d write down my thinky thoughts and share.... Read more »
Michael L. Hancock, II, Daniel Georges Bichet, George J. Eckert, Lise Bankir, Mary Anne Wagner, and J. Howard Pratt. (2010) Race, Sex and the Regulation of Urine Osmolality-Observations Made During Water Deprivation. Am J Physiol Regul Integr Comp Physiol. info:/
What's hot? What's not? What do you consider unappealing?A greater understanding of people different from ourselves makes for a more accepting and tolerant populace. Are attempts to deliberately evoke disgust by the sexual practices of "others" an important and worthy step towards achieving this goal? Or does it further stigmatize the minority "outgroup"? What if the "outgroup" is disgusted by the practices of the majority?Different strokes for different folksAnd so on and so on and scooby dooby doobyEveryday People------Sly & The Family StoneBrain Responses to Erotic FilmsWhat are the neural correlates of sexual arousal and disgust in heterosexual men and homosexual men viewing various types of porn (Zhang et al., 2010)? "Where can I sign up?" you say, both as a participant and a researcher. Or maybe you're horrified that such an experiment would be conducted by the scientific establishment. Pornography is a hot-button topic, and a discussion of its potential harms and merits is well beyond the scope of this post.1Disgust is considered to be one of the six basic emotions (Ekman, 1992). Given that disgust is a response to things that are physically distasteful or morally repugnant, this emotion has been examined in a specific evolutionary framework: "from oral to moral" (Rozin et al., 2009):According to the principle of preadaptation, a system that evolves for one purpose is later used for another purpose. From this viewpoint, disgust originates in the mammalian bitter taste rejection system, which directly activates a disgust output system. This primal route (e.g., bitter and some other tastes) evokes only the output program, without a disgust evaluation phase. During human evolution, the disgust output system was harnessed to a disgust evaluation system that responded not to simple sensory inputs (such as bitter tastes) but to more cognitively elaborated appraisals (e.g., a cockroach). ... Later, through some combination of biological and cultural evolution, the eliciting category was enlarged to include reminders of our animal nature, as wel [sic] as some people or social groups.In a rationale that is simple yet puzzling, Zhang et al. wished to see if the brains of gay men process disgust in a different manner from those of straight men.2To our knowledge, there have been few studies concerning the [sic] disgust in homosexual men. Whether the patterns of disgust differ between homosexual and heterosexual men is unknown. The participants were 16 heterosexual and 16 homosexual men (as identified by self-report). Bisexuals were excluded. The stimuli were 3 minute long film clips depicting explicit sexual activity between two men (M-M), two women (F-F), or a woman and a man (F-M). "Each type of erotic film was montaged with attractive short films." Subjects passively watched the films during scanning, then rated their levels of sexual arousal and sexual disgust after the fMRI portion had finished (shown below).Fig 1 (Zhang et al., 2010). Mean scores of the sexual films showing F–F, F–M and M–M in the two groups. F–F and M–M stimuli induce sexual disgust, respectively. Results of two independent samples test comparisons (homosexual versus heterosexual) are displayed. Blue indicates homosexual men; green, heterosexual men; the asterisk, p less than 0.01. Error bars equal 1 SD. NOTE: the level of sexual disgust was assessed by scores from 1 (extremely high) to 4 (extremely low), and the level of sexual arousal was rated from 6 (extremely low) to 9 (extremely high).It was no surprise to anyone that straight men were most turned on by F-M film clips and turned off by the M-M films. Straight guys were also a bit turned on by F-F (also not surprising given the popularity of girl-on-girl p0rn), although there was a great deal of variability. Also as expected, gay men were most aroused by M-M films. They rated their disgust as highest for F-F clips but were close to neutral for heterosexual p0rn (interestingly).3The neuroimaging data were analyzed using Disgust versus Rest as the comparison of interest.In the homosexual group, the F–F stimulus identified great activity in a large number of brain regions, including the left superior frontal gyrus, right and left medial frontal gyrus, left and right cerebellum, left middle occipital gyrus (BA 19), right lingual gyrus (BA 18), left precuneus, right middle temporal gyrus, left superior temporal gyrus (BA 38), left thalamus, and left supplementary motor area.In the heterosexual group, M–M stimuli elicited great activations in the left middle frontal gyrus, right middle frontal gyrus (BA 6), left inferior frontal gyrus (BA 45), right inferior frontal gyrus (BA 47), left middle temporal gyrus, right middle temporal gyrus (BA 37, BA 39), left superior temporal gyrus (BA 13), right superior temporal gyrus (BA 38), left inferior occipital gyrus (BA 18), bilateral caudate, bilateral thalamus, bilateral insula, left putamen, right parahippocampal gyrus, right cerebellum, right anterior cingulate (BA 42), and right amygdala.OK, so that's a bunch of areas that are activated relative to doing nothing (instead of relative to watching a neutral film). I won't try to interpret those results. How about comparing the Disgust vs. Rest responses of the gay and straight men? There was one region of the brain more active in each of the groups: left ventromedial prefrontal cortex for gay men (Fig. 4), and left cuneus [visual cortex] for straight men (Fig. 5).Fig. 4 (modified from Zhang et al., 2010). Aversive sexual stimuli compared to rest: stronger brain activation in homosexual men compared to heterosexual men in the left medial frontal gyrus (maximum at −1, 39, −12).... Read more »
Zhang, M., Hu, S., Xu, L., Wang, Q., Xu, X., Wei, E., Yan, L., Hu, J., Wei, N., & Zhou, W. (2010) Neural circuits of disgust induced by sexual stimuli in homosexual and heterosexual men: An fMRI study. European Journal of Radiology. DOI: 10.1016/j.ejrad.2010.05.021
Each year, the Earth’s terrestrial plants take in enormous amounts of carbon dioxide through photosynthesis. But exactly how much has been in question, due to a lack of data. Now, scientists have come up with a more detailed picture that could help refine climate models.
Using new observations and models, a team calculated that terrestrial […] Read More »... Read more »
Beer, C. (2010) Terrestrial Gross Carbon Dioxide Uptake: Global Distribution and Covariation with Climate. Science. DOI: 10.1126/science.1184984
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