The evolution of seed dispersal strategy, insights from the melic grasses and their relatives
By: William Brightly (Stromberg Lab)

Insect eggs are not passive structures deposited on leaves. They induce plant defenses that inhibit egg development or attract egg predators. Oviposition by the Large White butterfly Pieris brassicae leads to salicylic acid (SA) accumulation and local cell death in Arabidopsis. These responses are activated by a phospholipid elicitor perceived at the cell surface and share molecular similarities with PAMP-triggered immunity (PTI). However, expression of defense genes regulated by the jasmonic acid (JA) pathway are suppressed and larval performance is enhanced.

Phylogenetics has found its way into many different subdisciplines of biology, and has made lasting impacts in fields as disparate as community ecology and medicine. In evolutionary biology, the recent trend of phylogeny-oriented studies has been toward “scaling up”, and looking for very broad patterns in character evolution and diversification in attempts to make generalizations about the tempo and mode of evolution. This scaling up does come with a cost, in that we spend less time trying to understand how evolutionary processes work at the whole-organism level.

Evolutionary innovations are scattered throughout the tree of life, and have allowed the organisms that possess them to occupy novel adaptative zones. While the impacts of these innovations are well-documented, much less is known about how these innovations arise in the first place. Patterns of covariation among traits across macroevolutionary timescales can offer insights into the generation of innovation. However, to-date, there is no consensus on the role that trait covariation (i.e. integration and modularity) plays in this process.

Macroevolutionary studies of trait evolution are incomplete without the integration of speciation and extinction rates. The frequency of a character state on the tips of a phylogenetic tree is not only the result of the trait change per se but is also a function of lineage diversification if the character state is linked to speciation and extinction rates. In this talk, I will show three different examples of trait evolution linked to diversification.

The nucleus is extensively studied for its role in gene expression. However, growing evidences indicate that the biophysical properties of this organelle participate in cellular functions such as cell migration and pathogen killing; two processes critical for immune response. In this talk, I will describe our discovery of how immune cells undergoing confined migration squeeze their nuclei through narrow pores by forming a dense perinuclear actin network.