The UM student union, venue for the 2015 SSB standalone meeting. Photo credit http://bit.ly/1KhGgNN
Last week the Society of Systematic Biologists hosted its first standalone meeting from May 20-22 at the University of Michigan. The meeting included workshops, panel debates, three sessions of lightning talks, and an evening reception at the UM Museum of Natural History. I had a ton of fun meeting new people and catching up with old FIS (friends in science). I’m certain most of the ~200 attendants would agree the meeting was a huge success and I hope SSB will continue the tradition of the standalone meeting. In my post today I will highlight a subset of the talks I saw during the meeting. You can look back at tweets from the meeting with the hashtag #SSB2015.
Lightning talks
Four minutes for the presentation, one minute for questions. Ready, go!
Guanyang Zhang, Arizona State University: Islands can serve as a source of mainland biodiversity in Caribbean weevils
Pascal Title, University of Michigan: Species richness, distributions, and rates of speciation differ in Australian skinks (image below)
Image courtesy of P. Title
Lilian Hancock, Brown University: Preliminary phylogenies suggest CAM life history evolved multiple times in the Australian succulent genus Parakeelya
Yuan Tian, Ohio State University: Under a coalescent model with gene flow, there are several possible gene tree histories. Different species trees can have identical gene tree topologies, but different gene tree history distributions (image below)
Image courtesy of Y. Tian
Rosana Zenil-Ferguson, University of Florida: The rate of ploidy evolution depends on current ploidy level and can be modeled in an evolutionary context.
Shauna Price, George Washington Universty: A burst in the rate of speciation mirrors an increase in the rate of trait diversification in a clade of South American ants (image below)
Phylogeny where warmer colors represent faster rates with speciation on the left and trait diversification on the right. Image courtesy of S. Price
Orlando Schwery, University of Tennessee: MonoPhy is an R package that finds and visualizes monophyly issues using a bifurcating tree and a table with customized taxonomy (optional) as input. Test it with your data here!
Elizabeth Miller, University of Arizona: There is little evidence for temporal equivalency across genera, genera age is likely related to crown lineage age, and paraphyletic genera are common and large (image below)
Image courtesy of E. Miller
Panel discussions
In the four panel discussions, participants gave a ~25 minute presentation supporting each side of the debate and then the discussion was opened up to comments from the audience. I thought this format was a great way to involve lots of people from the meeting and foster thought-provoking discussion (disclaimer: in some cases, speakers presented a side of the debate in which they did not necessarily 100% agree).
Do we need more data or better models? Antonis Rokas and David Hillis debated whether we need more data or better models, respectively. Antonis pointed out that without data, models are useless. He presented a graph showing the number of citations over time for Felsenstein’s 1981 Journal of Molecular Evolution paper describing the application of maximum likelihood to the estimation of evolutionary trees from DNA sequences. In the first 10 years the paper accumulated ~80 citations, but that number took off once methods to collect data needed to implement the ML model were developed. Antonis also argued that the greatest discoveries of the past have been based on data, not models. On the flip side, David pointed out that even if we have 100% confidence in our sample but 0% confidence in our model, the result will be 0% confidence in our inference/conclusions. He also argued that when models are poorly developed, more data can lead to higher confidence in the wrong answer.
Species concepts are outmoded and hinder progress in evolutionary biology. Chris Simon and James Mallet debated whether species concepts were useful and whether species were “real.” James argued against species being real, presenting research from his lab showing high levels of hybridization and genome exchange across Heliconius butterflies and pointed to examples of extreme hybridization Anopheles mosquitos. He suggested evolution is more like a web than a tree of distinct groups. On the other hand, Chris Simon argued that species are important taxonomic categories useful for practical purposes such as education and conservation. She also reminded us that Ernst Mayr and Theodosius Dobzhansky, proponents of the biological species concept, didn’t believe hybridization between groups disqualified them from being good species.
Are molecular dates reliable for interpreting the history of life? Blair Hedges and Charles Marshall debated the usefulness of molecular dating. Charles argued that molecular estimates of divergence time were often “floppy” like a Dali clock (see an image from his talk below). He reminded us that molecular phylogenies and the fossil record measure different things, with molecular rates consistently older than the appearance of taxa in the fossil record. Charles said we need a better understanding of the rock record and how fossils are distributed in “rock space.” On the flip side, Blair argued that while molecular clocks have error, the error can be estimated and that our methodology continues to improve. He suggested that clock vs fossil controversies often involve calibration biases and that subsequent research has shown early clock estimates were not biased. Once the debate was opened up to the audience, the discussion turned to the promise of a method by Tracy Heath et al. that uses a fossil calibration method to combine extinct and extant species in a single evolutionary model.
Tweet from David Hillis: “Molecular clocks can be useful but we need to take sources of error seriously (like Dali clock) #SSB2015”
Accurate inference with comparative methods? The field isn’t paying enough attention to learning the limits of what we can know Wayne Maddison and Cécile Ané took a slightly different approach in their panel discussion. They presented four main topics (correlation between characters, reconstructing ancestral areas, processes of diversification, and unsolvable problems) with breaks between each for audience discussion. Wayne suggested that our success at estimating phylogeny over the last few decades has made us complacent and we must address the limits of comparative methods. He said a new, immature field shouts, “look what we can do!” while a mature field says, “what are the limits of what we can know?” Interspersed within the slides, Wayne included haikus based on the topics of the discussion. In his final haiku, Wayne touches on the idea of letting go and accepting the unsolvable problems.
In youth I sought it all
Now I hold a leaf and smile
Beauty I can hold
Thank you!
A big thank you to the organizers, moderators, workshop leaders, and participants of the 2015 SSB meeting and also to the lightning talk presenters who graciously sent me slides from their presentations. Let’s do it again soon!