Wednesday, February 29, 2012
Explaining mutualistic cooperation between species remains one of the greatest problems for evolutionary biology. Why do symbionts provide costly services to a host, indirectly benefiting
competitors sharing the same individual host? Host monitoring of symbiont performance and the imposition of sanctions on ‘cheats’ could stabilize mutualism. Here we show that soybeans
penalize rhizobia that fail to fix N2 inside their root nodules. We prevented a normally mutualistic rhizobium strain from cooperating (fixing N2) by replacing air with an N2-free atmosphere. A series of experiments at three spatial scales (whole plants, half root systems and individual nodules) demonstrated that forcing non-cooperation (analogous to cheating) decreased the reproductive success of rhizobia by about 50%. Non-invasive monitoring implicated decreased O2 supply as a possible mechanism
for sanctions against cheating rhizobia. More generally, such sanctions by one or both partners may be important in stabilizing a wide range of mutualistic symbioses.
From Host sanctions and the legume–rhizobium mutualism
Tuesday, February 28, 2012
I love the internets. I only had to type in 'Nematode quote' to find it. It's from from "Nematodes and Their Relationships", published in 1915 by Nathan Augustus Cobb who was apparently known as the father of US nematology.
His genial and humorous nature will ever be remembered, especially by those who were present at a certain meeting of the Helminthological Society of Washington. He appeared with numerous boxes and cartons which contained "A Collection of Holes," which he had assembled during his travels, and on them he proceeded to deliver a solemn and profound dissertation which rocked the audience with laughter. This was probably a satire on certain members of the society who always had entirely too much to say about things of which they knew little or nothing.
Monday, February 27, 2012
Biology-u-l -- Biology Undergraduate List is mainly for announcements made to L&S biology students. I recommend that all CCS biology students and any CCS student interested in biology classes and biology research sign up for this list (click the link to sign up). There aren't a lot of postings but there are some items of use. You can also check out the archives. Most posts are made by the two biology undergraduate advisors in MCDB and EEMB.
BIOnews is a more general list for the biology community at UCSB. There are some seminar announcements, course announcements, and a lot of people looking for pieces of equipment and chemicals. If you are part of the biology community at UCSB then you should sign up for this list.
Sunday, February 26, 2012
Reminded me of you all and thought you might want to read it to:
TL;DR: Basically the left handedness trait has been consistent at 10& since neolithic times. Scientists now think that this is an example of negative frequency dependent selection. The rare lefties have a slight fitness advantage in combat but only while they're percentage remains low. Neat!
Bacterial bioluminescence as a lure for marine zooplankton and fish
Some marine microbes glow in the dark. But why? A recent paper in PNAS suggests that far from deterring predators (one prior hypothesis), the behavior may serve to attract predators.
(F)indings show that the light emitted by the bacteria attracts predators, generally zooplankton, which ingest the bacteria but are unable to digest them. The bacteria, which continue to glow inside the zooplankton's guts, reveal the presence of the now-glowing zooplankton, which in turn, are attacked by their own predators -- fish -- who can spot them readily in the dark.
Further investigation of nocturnal fish that had fed on zooplankton showed that the luminous bacteria also survived the passage through the fish guts. "As far as the bacteria are concerned, their access to the fish digestive systems is like reaching 'paradise' -- a safe place, full of nutrients, and also a means of transport into the wide ocean," explained Prof. Genin
But why do the zooplankton simply not learn to avoid the potentially deadly glowing bacteria?
"In the dark, deep ocean the quantity of food is very limited, therefore it is worthwhile for the zooplankton to take the risk of becoming glowing themselves when contacting and consuming the particle with glowing bacteria, since the profit of finding rare food there is greater than the danger of exposing themselves to the relatively rare presence of predatory fish," explained Prof. Genin.
Saturday, February 25, 2012
Anyway, on ScienceDaily today:
In the Genes, but Which Ones? Studies That Linked Specific Genes to Intelligence Were Largely Wrong, Experts Say.
For decades, scientists have understood that there is a genetic component to intelligence, but a new Harvard study has found both that most of the genes thought to be linked to the trait are probably not in fact related to it, and identifying intelligence's specific genetic roots may still be a long way off.
"As is the case with other traits, like height, there are probably thousands of genes and their variants that are associated with intelligence, and there may be other genetic effects beyond the single gene effects -- there could be interactions between genes, there could be interactions between genes and the environment. What our results show is that the way researchers have been looking for genes that may be related to intelligence -- the candidate gene method -- is fairly likely to result in false positives, so other methods should be used."
Friday, February 24, 2012
Thursday, February 23, 2012
I thought I'd post a video of bat pollinators but I found this cool video from last year where they showed that in one bat pollinated vine the dish shaped leaves are adapted to produce a strong return signal to echolocating pollinators. The paper is in Science: Floral Acoustics: Conspicuous Echoes of a Dish-Shaped Leaf Attract Bat Pollinators
The visual splendor of many diurnal flowers serves to attract visually guided pollinators such as bees and birds, but it remains to be seen whether bat-pollinated flowers have evolved analogous echo-acoustic signals to lure their echolocating pollinators. Here, we demonstrate how an unusual dish-shaped leaf displayed above the inflorescences of the vine Marcgravia evenia attracts bat pollinators. Specifically, this leaf’s echoes fulfilled requirements for an effective beacon, that is, they were strong, multidirectional, and had a recognizable invariant echo signature. In behavioral experiments, presence of the leaves halved foraging time for flower-visiting bats.
Wednesday, February 22, 2012
The hypothetical primitive RNA replication process has a degree of sophistication that separates it from mere chemistry: it copies itself and allows copying mistakes, which themselves are copied in future generations. In other words, this is the process of self-reproduction with variations (as in Spiegelman’s system), not just organic synthesis. This is the very definition of life suggested by the developing theory of early molecular evolution. The same formula is derived by “word count” analysis, which yields the most frequently used words, of more than 100 known definitions of life. The recent discovery that both genes and genomes appear to have emerged originally as simple tandem repeats, with subsequent mutations increasing their complexity makes such definition even more attractive. One can view a genome as molecular habitat for emergence of “new life” in the form of expanding and mutating simple repeats. In that sense, and under the above minimalistic definition, life never stopped emerging, starting some 4 billion years ago with replicating RNA, and continuing to this day within the genomes of every living organism.
of neurons. These toxins prevent acetylcholine from being released and cause botulism.
There are seven known serotypes of botulinum neurotoxins, all of which are classified as category A bioterrorism agents!
In small doses, these toxins can be used to block the release of neurotransmitters that cause pain, muscle spasms and other symptoms associated with diseases like arthritis, asthma, and psoriasis. Interestingly, the protein that botulinum toxin targets exists in non-nerve cells also, but these cells lack the receptors needed for the toxin to enter and work in the cell. In recent experiments, botulinum toxin was attached to a molecule that non-nerve cells do have receptors for. These engineered botulinum toxins block the release of a protein from immune cells linked to inflammation, which is a major problem in many diseases. This very dangerous toxin could potentially be beneficial to people with chronic inflammatory diseases! Go figure.
Tuesday, February 21, 2012
Of course if bad novels have taught me anything about reviving things frozen in ice they've probably also unleashed some ancient evil or at least called down the wrath of ancient squirrels. We all knew the world was going to end in 2012 we just didn't expect ancient squirrels to be involved.
Monday, February 20, 2012
The evolution of the sporophyte in terrestrial plants is a controversial topic in evolutionary biology, due to two opposing theories that are equally supported. The “homologous theory” proposes that sporophytes descended directly from gametophytes in an aquatic algal ancestor that was retained in terrestrial descendants. This theory would then define a sporophyte as a “transformed gametophyte with the specific function of spore production”.
The “antithetic theory” proposes that the sporophyte is essentially an exaggerated zygote, originating when a zygote in an archegonium delayed meiosis and instead divided mitotically to form a blob of diploid cells. This theory indicates that the sporophyte evolved simultaneously in algae and bryophyte ancestors more or less at the same time they were transitioning onto land. This theory is also called the interpolation theory because it involves another step being “inserted” into the life cycle of plants.
There is evidence for both theories, and no real solution in sight yet, but it is still an interesting question worth pondering.
Hydrothermal vents are astounding communities that are a relatively recent discovery - only found in 1977 mostly by accident. Scientists were exploring a spreading ridge near the Galapagos and when they found a roughly 400C underwater volcanoes the last thing they expected was life- but lo and behold, life is what the found. And so much of it! Here are some pictures of some of the bizarre and adapted creatures that have survived the extreme conditions.
(Shown are deep sea shrimp, the "pompeii worm," a deep sea octopus, and the "ghost yeti crab."
Further research in hydrothermal vents reveals that there are actually two distinct types of vents - a black smoker vent
and a lost city vent:
The basic difference in these two vent systems is a key point in the theory of life's origin. The black smoker, which are directly above magma chambers, are low in pH and rich in methane, carbon dioxide, and hydrogen gas. However, the lost city vents have an alkaline environment, with a pH around seven or eight, and are located adjacent to spreading zones. This type of vent more closely resembles the early conditions of earth that gave rise to life. Further research has shown that the Lost City vents get their carbon from an inorganic source in the mantle and not the carbon dioxide in the water. It has also been hinted that alkaline protein gradients arose before other versions.
So much fascinating evidence around these communities and while they may or may not be the origins of life they are certainly worth investigating!
This further supports the hypothesis of phenotypic plasticity associated with large clonal size and old age. Nevertheless, even though such phenotypic plasticity possibly evolved across millennia, it may well be challenged by the unprecedented rate of environmental change imposed by current global climate change, including temperature increase and ocean acidification, and recent anthropogenic pressure on coastal areas resulting in changes in water quality, eutrophication, and nutrient load, particularly in seagrass meadows.
Sunday, February 19, 2012
The researchers focused on Hutterites, specifically the S-leut (Schmiedeleut) Hutterites of South Dakota. These Hutterites are a reproductively isolated population and have high birth rates, making them ideal for this kind of study, but more importantly, socioeconomic standing is fairly equal throughout the population because they practice a communal lifestyle.
All present married adults (396) who participated were required to fill out a detailed reproductive history questionnaire, detailing family births, deaths, and marriages. Married women participants who were of reproductive age were provided with journals so they can note their menstrual cycles and with pregnancy tests that they were instructed to use if their menses was late.
In order to determine fertility, three tests were used. First, interbirth intervals in the married women were examined under the assumption that longer intervals meant a harder time conceiving or a problem with fetal loss. Second, they examined the time between a woman's first menses after a pregnancy and the menses before the next pregnancy. Women using birth control were excluded from this part of the study. Last, they examined family size and in all the S-leut women born after 1900, including families throughout the United States and Canada.
The main conclusion drawn was that the more inbred a woman is, the more reduced her fecundity. The scientists hypothesize that this reduction could result from "recessive alleles that could inﬂuence pathways involved in gametogenesis, hormonal cycling, sperm transport, ovulation,
fertilization, or implantation". Duh.
In the journal Science this week is a paper that provides the best glimpse yet at what the common ancestor of the Plants and the Algae may have looked like.
Cyanophora paradoxa Genome Elucidates Origin of Photosynthesis in Algae and Plants
There's also a brief editorial commentary:
Contemplating the first Plantae
"The common ancestor of Plantae was an organism with very complex cells and a complex life cycle," Spiegel said. While some members of the super group Plantae may have less complex cells and life cycles, this does not mean they pre-date the common ancestor. "They're simpler because they lost parts, not because they originated that way."
Saturday, February 18, 2012
Fellowships are for 12 weeks, with start dates of 21 May or 18 June to late August/early September. Undergraduate and Masters students interested in pursuing scientific careers relating to the scientific disciplines represented are welcome to apply. This year, fellowships will be available in each of the seven divisions. Applications for fellowships are accepted between January 1 and February 28 of each year for the following summer. All applications must be received no later than February 28. Applications and more information are available online.
Friday, February 17, 2012
I don't think this story would have been picked up by the press quite as much as it has been if they hadn't included some adorable photos of grumpy looking tiny chameleons. The actual paper is in PLoS ONE this week. The photos are all over the interwebs
Rivaling the World's Smallest Reptiles: Discovery of Miniaturized and Microendemic New Species of Leaf Chameleons (Brookesia) from Northern Madagascar
Thursday, February 16, 2012
I found this really interesting article about Darwin’s bark spider. These spiders live in Madagascar and can create one of the largest known orb webs. These webs can be close to 3m in diameter with anchor lines spanning up to 25m and are built over a river or small lake. This paper studied the spiders and wanted to see if the webs were specifically designed to capture large prey, even vertebrates. The spiders’ silk is the toughest known spider silk, which implies that it could be possible for the Darwin’s bark spider to catch extremely large prey. However, this study of Darwin’s bark spider found that the largest prey captured was a dragonfly and that most of the animals caught in the webs were small insects.
Image from http://news.nationalgeographic.com/news/2010/09/photogalleries/100917-darwins-bark-spider-new-species-spider-webs-madagascar-science-pictures-strongest/#/huge-spider-webs-crossing-river_26175_600x450.jpg
Gregoric M., Agnarsson I., Blackledge T., and Matjaz K. 2011. Darwin’s bark spider: giant prey in giant orb webs? Journal of Arachnology, v. 39(2) p. 287-295.
Wednesday, February 15, 2012
Lycopodium is actually a type of club moss - which, as you may remember, is not a moss at all but a group of the seedless tracheophytes. Their very fine spores have been used for many purposes including early flash photography and as a fuel source in the first internal; combustion engine! When mixed with air, the spores are highly flammable because of their high fat content and their large surface area per unit of volume — a single spore's diameter is about 33 micrometers requiring about 30 laid side by side to span a millimeter and so 30x30x30=27,000 could be packed into a single cubic millimeter!
Tuesday, February 14, 2012
Haha yahoo news... but wow!
We postulate that desiccation tolerance is a primitive trait, thus mechanisms by which the first land plants achieved tolerance may be reflected in how extant desiccation-tolerant bryophytes survive drying. Evidence is consistent with extant bryophytes employing a tolerance strategy of constitutive cellular protection coupled with induction of a recovery/repair mechanism upon rehydration.
A new phylogenetic analysis suggests that: (i) the basic mechanisms of tolerance seen in modern day bryophytes have changed little from the earliest manifestations of desiccation tolerance in land plants, and (ii) vegetative desiccation tolerance in the early land plants may have evolved from a mechanism present first in spores.
Monday, February 13, 2012
If you guys want to know more about quorum sensing here is an old article from when it was first discovered.
Here's a great TED video of Bonnie Bassler, one of the leading researchers in quorum sensing, talking about her discoveries.
Sunday, February 12, 2012
This combines things I've learned from both CCS 20 and Parasitology!
Parasitism of Plant and Animal Hybrids: Are Facts and Fates the
Warm and Furry, but They Pack a Toxic Punch
A poisonous surprise under the coat of the African crested rat
Sphagnum moss doesn't just live in acidic, nutrient-poor and anoxic environments it creates acidic, nutrient-poor and anoxic environments thereby shutting out its competitors. From How Sphagnum bogs down other plants, Trends in Ecology and Evolution, 10 270-275:
Recent research on the organo-chemical composition of Sphagnum and on the fate of its litter has further clarified how this plant builds acidic, nutrient-poor, cold and anoxic peat bogs. The bog environment helps Sphagnum to outcompete other plants for light. Its morphology, anatomy, physiology and composition make it an effective ecosystem engineer and at the same time benefit the plant in the short term. This may have facilitated the evolution of the genus.
Saturday, February 11, 2012
(A Constant Flux of Diverse
Thermophilic Bacteria into the
Cold Arctic Seabed)
Many thermophilic bacteria have been found in and around seemingly inhospitable areas for these heat loving creatures (the arctic). These bacteria have been surviving as endospores rolling along the ocean floor until they reach warmer climate more suitable for thermophiles. Most likely these bacteria have been popping up out of Petroleum-bearing sediments and fractured ocean crust. It is interesting how these methods of protection have shaped the marine biome.
In, summary, the findings were:
The present results showed that lead, copper, cadmium and mercury toxicity decreased the total chlorophyll content of the leaves of bean seedlings. In response to heavy metal stress, the plants increased their proline, retinol, α-tocopherol and ascorbic acid content. The highest increases in proline, retinol, α-to- copherol and ascorbic acid content and greatest reduc- tion in total chlorophyll were found in plants exposed to mercury, followed by the sequence cadmium > copper > lead.
Friday, February 10, 2012
In the first minute or so, David Gallo shows clips of creatures living about two hours deep in the ocean. He then goes onto clips of shallow water creatures for the rest of the video.
He is super engaging and really gets you interested in the cool clips showing bioluminescence, squids mating, fighting, and camouflaging. The clip at ~4:20 is especially amazing.
Apparently, the lizards have a certain protein, most likely a heat sensitive one, that binds to the gut of the tick while it's feeding on the lizard. These proteins seem to destroy the spirochetes within the gut that cause Lyme disease, purifying the tick.
Thursday, February 9, 2012
Scientists can now begin a search for new life forms. If life is found in the lake's icy darkness, it may provide the best answer yet to whether life can exist in the extreme conditions on Mars or Jupiter's moon Europa.
Although this is very exciting scientifically there has been concern about possible contamination of samples and pollution of the lake from the anti-freeze and other chemicals used to keep the bore hole open and the drilling machinery working.
Wednesday, February 8, 2012
This video reminded me of how awesome biology is-so I thought I'd share*
*Disclaimer: don't watch if insects make you squeamish
Over the last 150 years, since Darwin's study of islands and his “Origin of Species,” island archipelagos have played a central role in the understanding of evolution and how species multiply (speciation). Islands epitomise the conventional view of geographic (allopatric) speciation, where genomes diverge in isolation until accumulated differences result in reproductive isolation and the capacity to coexist without interbreeding. Current-day Martinique in the Lesser Antilles is composed of several ancient islands that have only recently coalesced into a single entity. The molecular phylogeny and geology show that these ancient islands have had their own tree lizard (anole) species for a very long time, about six to eight million years. Now they have met, we can genetically test for reproductive isolation. However, when we use selectively neutral markers from the nuclear genome, on this naturally replicated system, we can see that these anoles are freely exchanging genes and not behaving as species. Indeed, there is more genetic isolation between adjacent populations of the same species from different habitats than between separate putative allospecies from the ancient islands. This rejects allopatric speciation in a case study from a system thought to exemplify it, and suggests the potential importance of ecological speciation.
Tuesday, February 7, 2012
- There's nothing more exciting than science. You get all the fun of sitting still, being quiet, writing down numbers, paying attention. Science has it all.
Sunday, February 5, 2012
(E)xperts say the fair-feathered variety are more easily visible to predators and susceptible to disease thanks to the genetic mutation. These weaknesses help make the albino bird all the more rare.
So enjoy the pictures before he, or she, gets eaten.
Saturday, February 4, 2012
Founder Effects Persist Despite Adaptive Differentiation: A Field Experiment with Lizards
(U)sing a replicated experiment in nature, we showed that both founder effects and natural selection jointly determine trait values in these populations.
A comment from one of the author's at ScienceDaily:
"We rarely observe founder effects as they happen in nature, but we know that it happens because islands are colonized by new species over time," said Kolbe. "What we didn't know was how these evolutionary mechanisms interact with each other. What we learned is that the differences caused by the founder effects persist even as populations adapt to their new environments."
Friday, February 3, 2012
It's one thing to find an urchin or a fish.
It's more fun to learn that a red urchin can live for 100 years, or that the fish you've just dicovered is a baby Opaleye that can breathe air when young!
Search a database containing: photos, common and scientific names, taxonomy, description, habitat, eats and eaten by, fun facts, frequently asked questions, and more.
This iPhone app works on an iPad too! And, is a great tool for teachers, naturalists, students, and anyone who is curious about tidepool life on the California coast.
Created by the Channel Islands National Marine Sanctuary, UCSB Marine Science Institute, LiMPETS (Long-term Monitoring Program and Experiential Training for Students), and volunteers from Citrix Systems, Inc.