Join us for this week's Smith Lecture as three of our own grad students will be giving mini talks. See below for info on each lecture

Speaker 1: Jeronimo Morales Toledo
Title: "Bisexual Climbers of Araceae In Deep Time: A Reexamination of Arthmiocarpus hesperus from the Late Cretaceous of South Dakota"
Abstract:
The study and re-evaluation of Cretaceous fossil plants offers insights to the early evolution of angiosperms prior to the establishment of modern ecosystems. Araceae display significant eco-morphological diversity (e.g., geophytes, climbers, epiphytes, helophytes, and free-floating aquatics), with their fossil record dating back to the Early Cretaceous (110 to 120 Ma). However, confidently assigned aroid fossils before the Cretaceous-Paleogene (K-Pg) mass extinction are limited to early divergent lineages (Orontioideae and Lemnoideae), hindering our understanding of the historical evolution of aroid subfamilies over deep time. This study focuses on Arthmiocarpus hesperus (Wieland) Delevoryas, a permineralized fossil from the Late Cretaceous Fox Hills Sandstone of South Dakota. Previously classified as a drupe from the fig family (Moraceae), it exhibits features consistent with Araceae. Through thin-sectioning and X-ray micro-computed tomography (μCT), we conducted a detailed examination resulting in 3D reconstructions of the seed and characterizing structures in multiple planes of section. Furthermore, we created a de novo character database by analyzing 300 species of fruits with μCT for fruit, seed and embryo morphology. This process resolved conflicting interpretations of fruit-seed morphology and anatomy, allowing us to identify additional characters useful for refining taxonomic affinities.The helically arranged sessile berries on a central spadix confirm affinities to Araceae, and features of the fruits and seeds such as berries with fibrous pericarp and stylar region, thick stylar region, a smooth seed coat, and a monocotyledonous L-shaped embryo suggest it is most closely related to members within the subfamily Monsteroideae. However, Arthmiocarpus presents a unique set of characters that differentiates it from extant and extinct members of Araceae. This investigation exemplifies how the subfamilies of extant angiosperms were integral components of Cretaceous ecosystems prior to the K-Pg mass extinction, contributing to the establishment of modern ecosystems.

Speaker 2: Paul Den Uyl
Title: "Genetic Characterization of Saxitoxin Producing Cyanobacteria Associated with Western Lake Erie Harmful Algal Blooms"
Abstract:
Saxitoxins (STXs) are neurotoxins produced in both freshwater and marine systems and are among the most potent known natural toxins. While genes encoding STX biosynthesis have been observed in Lake Erie, the organism(s) responsible for producing STXs in the region have not been confirmed. We used metagenomic tools to identify a full suite of STX biosynthesis genes in a high-quality metagenome-assembled genome (MAG) from the Anabaena-Dolichospermum-Aphanizomenon (ADA) clade of cyanobacteria. The order and sequence of sxt genes suggest the Lake Erie MAG is likely capable of producing saxitoxin (STX) and dicarbamoyl (dcSTX) congeners. The absence of a sxtX gene suggests an inability to produce neoSTX, one of the most potent variants of STX.


Speaker 3: Andrés Felipe Gonzalez Duran
Title: "Understanding mineral deposits in the Americas.
Brief summary: Overview of recent advancements on ore deposits in the Western margin of the Americas, including copper and gold in Canada and Chile, as well as emeralds in the Colombian Andes"