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)