A fun article came out in the January edition of the American Naturalist called "Insectivorous Bat Pollinates Columnar Cactus More Effectively per Visit than Specialized Nectar Bat". Why is it fun, you ask? It always seems like plants and their pollinators have co-evolved together, each gaining special adaptations (traits) that make the interaction more "lock and key". We can see this in the shape of a cactus blossom, and the snout of a long-nosed bat, which fits inside that flower so well. BUT, nature is always a little more complicated than that, and this paper shows how an insect-eating bat, the pallid bat that occurs along side the lesser long-nosed bat in Baja, where the cardon cactus lives, delivers many more pollen grains per visit to the flowers than the lesser long nosed bat. So in effect, it is a better pollinator, even though the other bat is specialized to only feed on nectar, and looks like the mammal version of a hummingbird. And partially this is precisley BECAUSE the insect-eating bat doesn't have a special long snout to get into the flower, and consequently gets pollen all over its head and shoulders as it clumsily tries to get at the nectar. It also seems to hang out at the flower for longer. Check out this video comparing the two flower visitation styles, and also this video the American Museum of Natural History created to describe the findings of the paper.
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A really interesting paper on the evolution of plant-pollinator interactions came out this week in Science. It also got press in the New York Times and the LA Times, which is great-- go science in the media! Why is it interesting, you ask? Because plants are master manipulators. They can't directly move themselves around to find one another to mate, so they get animals to move their plant sperm (pollen) to other plant eggs (ovules inside flowers). But the animals that are doing this service don't necessarily know they are helping a plant reproduce-- they are just in it for the reward, which usually takes the form of sugary nectar that is also in the flower (often hidden so that the animal has to squeeze in to drink, thereby rubbing the pollen they carried onto the female part of the flower). This paper shows that certain plants use other chemicals in addition to sugar in their nectar to change pollinator behavior. In this case, bees which drank nectar with caffeine (which is naturally found in certain plant species) were much more likely to remember floral scents in memory trials that the researchers performed. The implication is that flowers have evolved nectar with caffeine to cajole pollinators into remembering that flower (of all the types of flowers that pollinator might visit), and coming back to flowers with that scent cue for more reward, which would help that species of plant reproduce. Another cool aspect of the paper is that the authors studied the effect of caffeine on the bee brain, measuring and locating neural and receptor activity, to see how bees react to caffeine and form memories. Even though bees have very different brain structures from mammals, it seems that caffeine may work on similar neurotransmitter pathways in the two groups. This implies a unified mechanism of learning and memory development across many groups of organisms, which is truly cool. An awesome new paper in Science came out this January, called “Comparative Analysis of Bat Genomes Provides Insight into the Evolution of Flight and Immunity”. Why is this article cool? The authors looked at the genomes of two really different bat species and compared them. One is a big bat called the black flying fox (Pteropus alecto), which doesn’t hibernate or echolocate. And it is REALLY big, we are talking 1m wingspans! The other is a little insect-eating bat, which does hibernate and echolocate (Myotis davidii). So what they have in common, is that they are mammals that fly, and they both are potential reservoirs of diseases (as many bats are). They looked at the DNA of other mammals, and tried to find consistent changes in the two bat species’ genomes, which they could attribute to flight/disease resistance. They found several changes related to the “DNA damage checkpoints”. This is probably related to the evolution of flight, which would have put stress on the cells of organisms as they adapted to have higher/different metabolisms and oxidative stresses. It seems that this also is related to changes in bats’ immune systems, which are very different from other mammals, and might be why they are able to harbor so many diseases that they don’t succumb to. –Interesting take-aways from the article: Bat (and bird) genomes are smaller than other animals, which is consistent with a “selective sweep”, when natural selection has left a strong mark on the DNA by reducing diversity around a favorable mutation. The mutation could have been in some of these genes the researchers found that allowed flight to occur, since it seems to be a trait associated with high fitness. Another reason biologists like this article is that evidence of selective sweeps is SUPER fun for them, because it adds to our understanding of how evolution has taken place. –One of the coolest and weirdest parts of the article is a side note about the closest mammal lineage to the order of bats… the Equus lineage! Which means there was a common ancestor to both bats and horses that lived about 88 million years ago! I now like to spend time imagining what this animal might have looked like… Read here for another take on article, that is definitely pro-bat, which I appreciate :) |
AuthorLots of scientific research that is being conducted is fascinating... but often it is in hard to understand language. Here I will try to translate current research papers into the "cool science" they are underneath all that jargon. ArchivesCategories
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