The ChallenGen group has a new doctor!

by Alex Garcia-Cisneros

After a longer period than seems, at least to me, I defended my thesis the last 28th of June. Some members of the ChallenGen project joined the festive day together. The thesis analysed the biology, genetic structure and phylogeography of two starfish species, Coscinasterias tenuispina and Echinaster sepositus.

During these years of thesis work, we found a low genetic diversity in both asteroid species, lower than other echinoderms with the same distribution range. However, the reasons differ depending on the species. Low diversity in E. sepositus can be explained by a recent demographic expansion from few individuals with few alleles, while in C. tenuispina by the presence of asexual reproduction processes along all its distribution range, even with totally monoclonal populations. Furthermore, our results demonstrate that fissiparity in C. tenuispina increases with environmental instability. However, well-fed individuals do not lose their potential for sexual reproduction (development of gonads, only males). Finally, a last chapter in C. tenuispina presents at least one mechanism to avoid or postpone senescence and ensure persistence of clonal populations: telomere elongation.

Although there were nerves, or more precisely, I was extremely nervous, it was a really good festive day.

Me, with my son, receiving the PhD certificate from Marta Pascual, the principal investigator at the UB of the Challengen project, who was a member of the thesis tribunal.

New paper published: Spatio-temporal patterns of genetic diversity of Styela plicata in harbour populations

by Xavier Turon

We add another paper to the Styela plicata history: “Stochasticity in space, persistence in time: genetic heterogeneity in harbour populations of the introduced ascidian Styela plicata”, by Mari-Carmen Pineda, Beatriz Lorente, Susanna López-Legentil, Creu Palacín and Xavier Turon, which has been published today (23rd June) in PeerJ.

In this study, we analysed genetic structure of the populations of Styela plicata in 9 harbours along the Iberian Mediterranean coast and adjacent Atlantic waters (>1,200 km range) at two time points 5 years apart (2009 and 2014). Using COI sequence data of ca. 400 specimens, we found strong spatial genetic structure, with significant differences among many populations, but no significant differences among years. Our results revealed spatial genetic heterogeneity and temporal homogeneity in S. plicata, suggesting a limited role of recurrent, vessel-mediated transport of organisms among small to medium-size harbours. Our study area is representative of many highly urbanized coasts with dense harbour networks. In these environments, the episodic chance arrival of colonisers appears to determine the genetic structure of populations and the genetic composition of these early colonising individuals persists in the respective harbours, at least over moderate time frames (five years) that encompass ca. 20 generations of S. plicata.

This article is yet another instance of the importance of the temporal component in studies of introduced species to unravel processes occurring during secondary dispersal of non-indigenous species.

Map of the Iberian Peninsula (NW Mediterranean) showing the sampling sites of Styela plicata. Pie charts represent haplotype frequencies for the COI gene in each population analysed in 2009 and 2014.

Another ChallenGen meeting

by Marta Campos

On the 20th June, the members of ChallenGen Project held a general meeting at the Biology Department of the University of Barcelona.

It was our pleasure to learn about ongoing work of the MarSymbiomics project, with which several collaborative papers have been prepared.

This encounter gave us the opportunity to interact with each other, and to present the latest news and updates on howour research and work is going on . During the last trimester, for example, Maria was in Venezia doing a research stay, Alex and Carles worked with informatics analysis and Clara and Marc prepared two oral communications for the XVI day of evolutionary biology, organizated by the Institute of Catalan Studies. We also learnt about the last results published or submitted within the framework of ChallenGen.

Moreover, the CEAB-CSIC researcher Iosune Uriz was our invited speaker and explained us the main results until now of her project MarSymbiomics.

It was a great week start!