Quantitative Cladistics and the Use of TNT

Interesting workshop in Quantitative Cladistics organized by Pablo  Goloboff and Claudia Szumik at Els Hostalets de Pierola, Barcelona (Spain). The workshop will cover the basics of parsimony analysis and character optimization, tree-searches, diagnosing and summarizing results efficiently, and measuring group supports.

The course will be informal, with extensive hands-on exercises which will help students get familiar with the main aspects of phylogenetic analysis using TNT. For each of the units in the workshop, there will be a lecture (one to two hours, depending on the topics), then switching to exercises illustrating the points just seen in the lecture. Switches between "lecture" and "hands-on" mode will be dynamic, depending on how students advance on the exercises.The workshop will make extensive use of TNT. There will also be a demonstration and some practice withGB->TNT, a program to create TNT matrices from GenBank data (in turn, GB->TNT requires installation of some alignment program, ideally Mafft or Muscle and possibly BioEdit to inspect alignments). ENJOY!

 

Polyploidy and the rise of invasiveness in marine seaweeds

A good part of research suggests that only a limited number of species within algal orders or just a single genetically distinct lineage from within the same morpho-species complex, becomes suddenly invasive. In plants, the switch to invasiveness has been recently related with differences in ploidy levels, meaning that genetic attributes such as polyploidy and high chromosome counts may be the drivers for the phenomenon (Pandit et al. 2011).

 

In their elegant study, Pandit and co-authors (2011) prove that endangered plants exhibit disproportionally low levels of ploidy and chromosome numbers compared to invasive plant species. Similar to hybridization therefore, polyploidy may lead to the production of novel and greater numbers of genetic variants, which increases the probability of a successful invasion. But what is happening in invasive marine seaweeds?

Complex Life Cycles and their contribution in species relocation, adaptation, survival: lessons from Rhopaloeides odorabile, a common sponge of the GBR

Like other sessile invertebrates (such as corals), sponges represent important components of the Great Barrier Reef in terms of biomass production, diversity levels and pelagic processes. Like corals however, sponges have specific eco-physiological windows for survival, characterized by rigorous temperature optima. In other words, sponge populations suffer seriously thermal stress associated with increases in sea surface temperature, a consequence of climate change.

Larvae of the sponge Rhopaloeides odorabile in the GBR show a remarkable thermal tolerance compared to adults. Rhopaloeides larvae are capable of surviving and metamorphosing in seawater temperatures even 9 ^oC above the annual maxima. This suggests that the chances for Rhopaloeides to survive global warming are great given the capacity of the species to relocate towards more suitable habitats via larval dispersal. But the question is, how?

Neotrygon Maskrays, a Complex Chondrichthyan Radiation in the Cenozoic: How and When!

Neotrygon maskrays are distinguished by a dark mask-like band over the eyes and represent an ideal group for understanding how evolutionary forces, geography and environmental dynamics may have shaped marine populations in the Indo-Australian archipelago. This is because, they are confined to the Indo-West Pacific and four of the five nominal species exist as narrow-ranging endemics along the interface between the Australian and Eurasian tectonic plates. Further, they inhabit shallow coastal and continental shelf waters. This habitat makes them easy targets to population fragmentation due to environmental pressure, such as cycles of glaciations responsible for the formation of phylogeographic breaks and/or contact zones.
In this paper, Melody assesses the partitioning of the genetic diversity within the genus, the taxonomic validity of some morphs and the timing of species divergence. The results are interpreted in the light of large scale paleo-climatic and geological events. Finally, conclusions are discussed given the formation of biogeographic barriers, responsible for vicariance and population contraction/expansion or secondary contact mechanisms across the Indo-Pacific.