Friday, April 1, 2011

The coolness of flowers, it never ends

I know I keep doing this, but LOOK at this flower. Does it even look like one?

(from here. There are more pictures. GO!)

This particular individual is Ceropegia dolichophylla (dolichós = long, phylla = leaf. There, now it's not just greek to you!). This genus has these distinctive flask-shaped flowers that are pitfall traps for small flies.

Have a look at some of the variation within the group:

(Just one of the many bizarre flower shapes out there. From here)

Pollination in Ceropegia is thought to go something like this: Flies come to the flower, attracted by the scent. They fall into the base, and are trapped overnight, leaving the next day with pollinia (chunks of pollen) stuck to their mouthparts. Undignified!

In the case of C. dolichophylla, the type of flies primarily attracted are milichiid flies, many of which are kleptoparasites on the prey of spiders . This refers to the way these flies steal food from hardworking spiders, sucking the blood and juices of their prey out from under them.

Desmometopa sp., Milichidae
(see that milichiid sharing the spider's meal of ant juices? No shame. From here)

The group of scientists working on C. dolichophylla found that instead of smelling like rotting meat (larvae food), they found that the dominant compound is very similar to those mainly found in insect glandular secretions, a.k.a sex or alarm pheromones. What does that smell like? In the words of the authors: "The floral scent of Ceropegia dolichophylla, as detectable by the human nose, can be described as sour-sweet with musky and sourish-metallic components."(1)

Since we don't know much about milichiid sex pheromone smells, they could not be sure which one C. dolichophylla is mimicking. They do think it's likely to be food, because the females are extending their mouthparts when they land, presumably to taste where that delicious smell is coming from.

(Probably more noms than sexytiems. From here)

So, yes. These flowers either smell like bug sex or death. How cool is that?

1. A. Heiduk, I. Brake, T. Tolasch, J. Frank, A. Jurgens, U. Meve & S. Dotterl. (Oct 2010) Scent chemistry and pollinator attraction in the deceptive trap flowers of Ceropegia dolichophylla. South African Journal of Botany, Volume 76, Issue 4, Pages 762-769. DOI: 10.1016/j.sajb.2010.07.022.

2. J. Ollerton, S. Masinde, U. Meve, M. Picker & A. Whittington. (June 2009) Fly pollination in Ceropegia (Apocynaceae: Asclepiadoideae): biogeographic and phylogenetic perspectives. Annals of Botany, Volume 1o3, Issue 9, Pages 1501-1514. DOI:10.1093/aob/mcp072

Wednesday, March 9, 2011

Monday, March 7, 2011

Why is pollen yellow?

A (very) recent editorial out in the Journal of Biogeography makes a very interesting link between why pollen tends to be yellow in a great majority of plant species, and another, more popular question. Namely, why are there so many species in the tropics?

Bee Speed!!!
Busy bee doesn't bother thinking about such things

First, let's tackle the question of why pollen is yellow.

The short answer is, pollen is yellow because they contain compounds that make them yellow. Sounds obvious, but stick with me. These compounds are a class of chemicals known as flavonoids, which are also abundant in citrus. Aha! But the more difficult question is, why are plants packing their pollen with this stuff?

Well flavonoids are known to have UV-B protective properties. They might help protect the plant's gametes from accumulating harmful mutations.

White Rose
Plant uses sunblock to prevent those unhealthy mutant babies.

Right! Second question: Why are there so many species in tropical rainforests? There are a few ideas on how this happens, namely that the tropics are a cradle (species are "born" faster), or a museum (species go extinct slower than in other places).

Confused? Read this. It'll help.

What John Flenley proposes in his editorial is that the reason why there are so many species in the tropics is connected to UV-B radiation. Plants (and animals!) in the tropics, especially those at the top of mountains, are exposed to higher levels of UV-B radiation than anywhere else. This may lead to higher levels of mutation, which may provide the genetic variation (the "stuff" evolution works on) within species for faster speciation.

Tropical rainforest
Like giving evolution a 120-pack crayola box instead of a 8-pack to colour with.

Just a little food for thought, the next time you look at/pick/smell that that flower or eat an orange.

Further Reading:
Flenley, J. R. , Why is pollen yellow? And why are there so many species in the tropical rain forest?. Journal of Biogeography, no. doi: 10.1111/j.1365-2699.2011.02480.x

Sunday, March 6, 2011

Sunday shiny

The Blaschka glass collection of invertebrates and plants. (Click on photos for flickr galleries)

Glass Flowers: Dahlia tenuis


Glaucus longicirrus

Saturday, March 5, 2011

Quick note

I know this blog was set up to be an arthropod outreach thing, but guess what? One of the two contributors has jumped kingdoms to plants.

So in the interests of not letting this blog die a lingering death from neglect, I'm going to willfully modify the prior assumed arthropod centric focus to arthropods AND plants.

So yes, this blog is still backbone-free.

What's awesome like Batman?

Behold, the Bat flower.

Tacca chantrieri
I mean, just look at that.

When we think about flowers, we usually think of something attractive and/or sweet smelling, like a rose or a lily or a daisy, with bees and butterflies busily feeding on their nectar or pollen. However, this leaves out a great majority of plants whose flowers have adopted different strategies in order to attract other, less well known pollinators, such as flies or even mammals such as shrews or bats. You might know of the Rafflesias, which smell like rotting meat and attracts carrion flies.

Bat flowers, or Devil Flowers (genus Tacca) get their common name from their unusual bat-like (or demon-like) appearance, not because they are pollinated by bats (those have a coolness all of their own). These are members of the yam family (Dioscoreaceae).

...Wait, yam?

Yep, bet you didn't see that coming. A yam. But whatever yam you're thinking, you're probably wrong. The subject of another post!

These are found in tropical Africa, Southeast Asia and Australia, showing that the tropics are just chock-full of oddness! There is some controversy about how exactly these plants are pollinated, because while they look like they're pollinated by flies, a recent study finds that they seem to be perfectly happy self-pollinating.

Tacca Chantrier
Does this look like a plant that does not play well with others? Wait, don't answer that.

Some of the more evolutionary biology-inclined among you are probably already asking: If these plants are happy selfing, then why so much fuss and bother producing these spectacular flowers?

I don't know either. But I would like to find out.

Further reading:
Predicting mating patterns from pollination syndromes: the case of "sapromyiophily" in Tacca chantrieri (Taccaceae)

Monday, August 3, 2009

Since theonlinecitizen is down right now

Sorry everyone for letting this blog lapse. I'm posting here because keeps crashing, and I think there should be a stable mirror of the content. The original can be accessed here


God sneaks into our classrooms
Monday, 3 August 2009, 11:13 am | 361 views
Lim Say Liang

In 2005, after complaints from the public, the Ministry of Education (MOE) rapped the knuckles of teachers who openly proselytize in class: “’The MOE takes a firm stand on religious proselytising by teachers,” the statement said. “Our schools are secular, and teachers should not be engaged in proselytizing their students. Otherwise we face a real risk of undoing the multicultural and multi-religious sensitivity and harmony that Singapore has built up over the years, and which our schools seek to cultivate in each new generation….”

But that hasn’t stopped some teachers from trying an endaround. Who knows exactly where coursework ends and proselytising begins? What if proselytisation looks like coursework?

Michelle (not her real name) was given two comprehension passages last year when she was in Secondary 2. The first was a National Geographic article about individuals obsessed with the Loch Ness Monster. The questions her English teacher drew up were not out of the ordinary. (The Loch Ness Monster has been used in Evangelical Christian curriculums as evidence that disproves evolution.)

The second was culled from a website. It mentioned the global flood from the biblical story of Noah and the Ark, made other biblical references, and there was criticism of those who accept the Theory of Evolution. “The questions didn’t require critical-thinking at all,” said Mullai Pathy, Michelle’s tutor who is trained by the National Institute of Education. “These were questions that sought to reinforce particular religious beliefs.”

Shortly after, a Creation-Evolution debate was staged in Michelle’s class. She and several classmates protested the topic, citing its obvious religious nature. The teacher waved aside their concerns. A visiting teacher sat in during the debate. Neither raised objections when the “Creation team” quoted from the bible. At the end of the debate, they were commended for raising “many points.” “Not everyone in my class is Christian,” said Michelle.

According to the U.S. National Academies of Sciences, “Evolution consists of changes in the heritable traits of a population of organisms as successive generations replace one another.” (For a more detailed explanation, please see here.)

Creation or Creationism is the belief that God created everything, basically. However, there are many views as far as Creationism is concerned. (See here.) The problem arises when Creationism creeps into the secular classroom, particularly Science. Creationists tend to be scriptural literalists, who see the Theory of Evolution as a threat to their beliefs.

Michelle is learning biology this year. Recently, her biology teacher acknowledged aloud the perfection of God in the story of the Creation of Man. This occurred during a lesson on the human digestive system.

Since proselytising-educating is prohibited in most schools, some Creationists have attempted to make Creationism respectable enough for the classroom.

It’s right there in the Mini Science Encyclopedia (MSE). At least 10 Primary schools offer the “optional” reference book to their students. Creation-material dates back eight years to the 3rd edition. (It is likely that a number of school libraries hold the title; the Lee Kong Chien Reference Library does, under “Science Encyclopedias, Juvenile.”)

“Your child’s natural curiosity is reinforced,” markets the online catalogue “and at the same time, he or she learns more about science and the world we live in.”

A depiction of what appears to be Adam and Eve heralds the chapter on Evolution. The title “Creation” floats over their naked silhouettes as they hold hands in what appears to be the biblical Garden of Eden. Below them are the title “Evolution” and the subtitle, “Hypothesis on The Origin of Species.”

“First of all, you can’t mention Creation in a chapter on Evolution, it’s completely inappropriate,” said Douglas (not his real name), a biologist. “It’s equivalent to starting a chapter on geology and saying some people believe the earth is flat and some people believe the earth is spherical. Creation is religion. Everybody knows Creation is religion. This is not supposed to be in a science book—ever.”

He went on to detail what he referred to as “errors” which Ang Woon Chuan, the author, makes in describing the Theory of Evolution. “Rubbish… Stupid…. Reference books should be rectifying mistakes, not perpetuating them.”

After Ang’s “Theory of Evolution”, Douglas came to the last page of the MSE, the other “main school of thought”: “Another view is that God created the Heavens, the Earth and all creatures including Man. This is the Theory of Creation.”

“By definition, God has nothing to do with science and this ‘Theory of Creation’ is not accepted scientific knowledge,” Douglas explained. “It’s a matter of fact that this has been rejected over and over and over again. There is not a single article supporting this position in any of the scientific literature of the last fifty years,” he said.

For example, none of the 6000-plus scientific journals that are covered by ISI Thomson Reuters, a watchdog of scientific journals, publish Creationist or Intelligent Design articles. U.S. Courts have also repeatedly investigated Creationism and most recently, Intelligent Design, and ruled that both are religion and not science. (See here: Decision.)

Some Creationists have decided to start their own journals and peer-review each other.

Singular, “God” connotes monotheism, a belief in one Supreme Being. Where does that leave religions that technically have no gods, like Buddhism or religions which are polytheistic, like Hinduism? What of agnostics and atheists?

“How can you have this in a science reference book in a country that is supposed to be secular?” Douglas asked, agitated. “Totally unacceptable—this is discriminatory. If I am a Buddhist, what am I suppose to think? That all of a sudden, my religion is wrong? Because that’s what it is saying.”

He added, “This also causes rifts within religions; there is a whole lot of Christians who don’t have a problem with Evolution, the same goes with Muslims. Then you get the radicals and now you have a problem, because they push a literal interpretation of scriptures. For this reason alone, this book would be outlawed in a heartbeat and taken off the shelves in the U.S. and in Europe. Promoting this book in a secular school is uncivilized behaviour.”