Metacommunities in Brazil

My name is Melissa Guzman, I recently finished my first sampling season in Restinga de Jurubatiba National Park. While I won’t be writing what is like to be a foreigner in Brazil, Andrew MacDonald a colleague in my lab already did that, I will give a brief description of my work in Brazil and why I think is so exciting.

A recent concept in ecology is the idea of metacomunities. Which is based on Levin’s original idea of metapopulations, where a set of populations from one species interact via dispersal. In metacommunities, several species that interact also disperse to other communities. While theoretically this field has advanced very quickly, it has been lagging behind in empirical work.

The macro invertebrates that live inside bromeliads provide an excellent system to study metacommunities, since the invertebrates interact in a food web, but they also disperse from one bromeliad to another during their adult life stages. For this reason, I set out to answer a series of questions related to how dispersal shapes this community.

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Bromeliads

The first step in order to study this, is to know how far the species disperse. Dispersal has been typically been measured by using mark and recapture experiments, and while these have been fairly efficient in measuring dispersal, it is very time consuming and very hard to do for a whole food web. Therefore, I decided to use next generation sequencing and population genetics in order to infer dispersal distances for a few species that compose the bromeliad food web.

During my time in Brazil, I collected a few individuals from seven points across the Jurubatiba National Park, all the way south to the Restinga in Arraial do Cabo, the Restinga of Marica and finally the Restinga in Ilha Bella, for a total of ten sampling points. While collection was very hard due to the very dry year, we managed to collect enough top predators and prey in all sites.

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Restinga ecosystem

Now back in Canada, I will genotype ten individuals of each species in each of my ten sites. To do this I will use a technique called GBS (genotyping by sequencing). Since none of the invertebrate species I will be using have a sequenced genome, other techniques such as micro-satellites are quite hard to do.

For GBS, restriction enzymes digest the genome and from those restriction site cuts, where the sequence is known, we can sequence short sections of the genome. Then to obtain the genotypes of the populations, we compare the genotypes of all the individuals inside that population.

Finally to estimate the dispersal distance of each of the species we compare the genotypes of all the ten populations and estimate the similarity of genotypes between them. In theory, if there is dispersal between the populations, then the genotypes will be more similar. On the other hand, if there is no dispersal between populations, then the genotypes will be more different.

We expect that the type of dispersal and the body size will affect how far each species can disperse and therefore, the role of dispersal for that species in the community.

I would like to thank everyone at the limnology lab both in Macae and in Rio. Without their help I wouldn’t have been able to have such a successful field season. And keep tuned for the final results!

Thanks for reading!

Melissa Guzman is  PhD student at the University of British Columbia supervised by Diane Srivastava. Her main interests are metacommunities, particularly how dispersal affects communities. Currently she uses bromeliad invertebrate communities as a model system. 

Click here to read this text in Portuguese

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