Earlier this month, we ventured down to Coney Island to collect shells for our Aiptasia and Berghia cultures! As nocturnal animals, the Berghia are overjoyed to have additional shelter to relax under and to lay their embryos on. Meanwhile, the Aiptasia are on to bigger and better tanks, enjoying spacious accommodations in our new culture set-up that is generously decorated with seashells. Here’s to more shells and beach trips in the new year!
Figure 1. Polyclad flatworms are dorsoventrally flattened as adults, some species develop directly into this body plan, others develop indirectly through larval forms with transient features such as lobes and ciliary tufts and bands. (a) Adult polyclad, Yungia sp. (b–d) Hatchlings of direct developing species; Euplana gracilis (b), Notocomplana sp. (c) and Echinoplana celerrima (d). (e–k) Hatchlings of indirect developing taxa; newly hatched Müller's larva of Cycloporus gabriellae, (e), newly hatched Müller's larva of Prosthecereaus crozieri (f); Prosthiostomum acroporae shows ‘intermediate development’ with the embryo developing eight larval lobes inside the egg capsule (g (i)), but most individuals undergo intra-capsular metamorphosis (g (ii)); Müller's larva of Prosthiostomum siphunculus (h), four-lobed Goette's larva of Stylochus ellipticus (i), ventral (j (i)) and dorsal (j (ii)) view of 10-lobed larva collected from the plankton, species unknown; and lateral view of 10-lobed larva collected from the plankton (k). B-K scale 50 µm.
I, along with my colleagues Kate Rawlinson and Bernhard Egger and my former advisors Michael Cummings and Allen Collins, published a new paper on the phylogenomics of polyclad flatworms and larval evolution in the clade in Royal Society Open Science (https://royalsocietypublishing.org/doi/full/10.1098/rsos.220939#d1e2064)! It took a bit of time to finish (7 years!), but we're excited to see it out.
Our transcriptome phylogeny provides much stronger support for deeper nodes than previous single- or multi-gene trees, and we recover a new monophyletic clade of early branching cotyleans. We then used ancestral state reconstructions to investigate ancestral modes of development within Polycladida and more broadly within flatworms. In polyclads, we were unable to reconstruct the ancestral state of deeper nodes with significant support because early branching clades show diverse modes of development. This suggests a complex history of larval evolution in polyclads that likely includes multiple losses and/or multiple gains. Our ancestral state reconstruction across a previously published platyhelminth phylogeny does support a direct developing prorhynchid/polyclad ancestor though. This suggests that a larval stage in the life cycle evolved along the polyclad stem lineage or within polyclads.
I am now two weeks into my position as Assistant Curator of Malacology and Assistant Professor of the Richard Gilder Graduate School at the American Museum of Natural History! It has been an exciting time with all of the preparations of starting a new position, and I hope to have my lab and office set up within the next month. I've really been enjoying starting up at the museum! For those of you that are interested in joining my lab at AMNH, check out the Join us! page here on my website. Until next time!
I will start as an Assistant Curator of Malacology and Assistant Professor of the Richard Gilder Graduate School at the American Museum of Natural History in New York City in October 2022! The Goodheart lab is interested in folks who want to study marine invertebrate biodiversity and evolution, especially those interested in sea slugs and the evolution of complex phenotypes, like nematocyst sequestration. Please email me if you are interested in joining my lab!