Diversity

I’ve made it to Lizard Island Research Station, and have finally begun the actual sampling work that brought me to Australia!

The last week has been rather incredible. To get to the island, my field partner and I flew in a 5-seat airplane that held only us and the pilot. I’d never been in such a small plane, and was actually a little nervous as we walked out onto the tarmac! I was expecting the flight to be bumpy, but it was actually really smooth – even the landing was more smooth than most I’ve experienced.

Hmm... Well, maybe it was worth getting up so early

Hmm… Well, maybe it was worth getting up so early

I most certainly did not have any theme songs going through my head during the flight. Especially not Indiana Jones or Jurassic Park.

I most certainly did not have any theme songs going through my head during the flight. Especially not Indiana Jones or Jurassic Park.

Katia window

Landing at LizardSince I’ve been here, I’ve had the chance to settle in, meet people, and begin my coral-search. The station and the people in it are lovely, and the reefs are too!

So now that I’m here, I should probably explain my project a little better. I mentioned before that I was searching for the normal, or ‘good’, microbes in the corals. The problem is, different coral species have different ideas about what is good for them, and environmental conditions can change those ideas even within an individual coral colony. For example, corals that grow fast and live in bright sunlight might get plenty of sugars from their algal symbionts, and bacteria that collect or produce essential protein compounds might be important for the coral. But slightly deeper-water corals that don’t get as much sunlight for photosynthesis could have a different balance of requirements, and it may be more beneficial to associate with other kinds of bacteria. I don’t know, that just came off the top of my head – it’s just one hypothesis that might be interesting to test some time in the future!

It’s hard to test hypotheses like that right now, though, because there are confounding factors that complicate things. If we compared the bacteria in deep-water corals to those in shallow-water corals, we would probably see quite a few differences. But if the deep-water corals have other things in common (for instance, if they’re all related to one another, or grow in similar shapes), it is difficult to tell whether those differences are actually due to their unique environmental conditions, or if they’re byproducts of the other factors.

To help out with such hypothetical future studies, we plan to describe the coral microbiome in the context of the various species’ relationships to one another. If a certain group of corals has evolved to associate with bacteria that other corals don’t, we can take this into account when we ask other questions, like “Why does Species A get diseases more often in high-temperature water than Species B does?”

On a more basic level, we just want to describe something new. To my knowledge, nobody has ever before taken a peek at the microbes that associate with the coral Galaxea fascicularis. And who knows – maybe there’s some crazy bacterium in it that makes a new type of antibiotic and lives nowhere else! We’ll never know until we look. So we’re exploring the diversity of microbes in many coral species that have simply never been sampled.

My description of the project’s probably not entirely clear yet, but that’s at least a good enough introduction to it to segue into what I’ve been doing for the last week. I can’t sample from all the different groups of corals unless I know how to distinguish them from one another, so I’ve been working on my species ID. It’s not so easy. Here’s an example. Below, I have pictures (that I took this week) of 5 different coral species:

Diploastrea

A

Bushy Acropora

B

C

C

D

D

E

E

F

F

These corals are pretty common and I’ve actually chosen them because they were relatively simple to name. They are all related to one another like this:

In this diagram, relationships between species are displayed like a family tree. Species that are more directly connected with lines are closer relatives, so three Acropora species are closer to one another than any of them are to Diploastrea, for example.

Evolutionary biologists use the term clade to describe groups of organisms that are more related to one another than to any other organism. In this diagram, the three Acropora species form a clade, as does the combination of Symphillia and Echinopora, as well as the combination of SymphilliaEchinoporaand Diploastrea. The combination of Acropora nobilis and Diploastrea heliopora does not form a clade, even though they appear side by side (the location of the names does not matter, only their connections via lines). Does that make the diagram clear? I was struggling to put it into words, so let me know.

Of these corals, we would expect that Symphillia and Diploastrea would have microbial communities more similar to one other than either do to any of the Acropora species, for example. But can you guess which corals get grouped together by just looking at them? My task is to make these assessments so that we get a nice, broad sampling of coral diversity. I’ll put the answers in my next post.

 

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  • Cammie

    Beautiful photos and excellent food for thought! What a lovely adventure. Also, I’d like to test my coral ID skills, perhaps can you provide a key to the species in the photos! Love your work, miss you friend!

  • It looks so pretty there!!