Fortin, D. | bioRxiv Science

bioRxiv2020

A theory of the use of information by enemies in the predator-prey space race

We currently lack a comprehensive theory about how behaviourally responsive predators and prey use the information they acquire about the environment and each others presence while engaged in the space race. This limits our understanding of the role of behaviour in trophic relationships and our ability to predict predators and prey distributions. Here we combined a simulation model with a genetic algorithm to discover how predators and prey behaving optimally should use information in environments with different levels of heterogeneity in prey forage distribution and prey vulnerability. Our results demonstrate the key role of movement unpredictability in successful strategies for both predators and prey, supporting the shell-game hypothesis. We however reveal striking differences between predators and prey in the magnitude of this unpredictability, and in how it varies with the environment. Our work offers a robust theoretical framework to better understand predator-prey space use and interpret empirical studies.

animal behavior and cognition↗

bioRxiv2019

Position-sensing established duringcompaction dictates cell fate in themammalian embryo

Precise patterning within the 3-dimensional context of tissues, organs and embryos implies that cells can sense their relative position. We still understand relatively little about how cells sense their relative position within small groups of cells. During preimplantation development, outside and inside cells rely on apicobasal polarity and the Hippo pathway to choose their fate. Despite recent findings suggesting that mechanosensing may be central to this process, the relationship between blastomere geometry (i.e. shape and position) and the Hippo pathway effector YAP remains unknown. To address this, we used a highly quantitative approach to collect and analyse information on the geometry and YAP localisation of individual blastomeres of mouse and human embryos. We find that the fraction of YAP in the nucleus responds to the proportion of exposed cell surface area rather than blastomere shape. To directly test the influence of blastomere position on YAP localisation we developed an approach using hydrogel based cylindrical cavities to alter blastomere arrangement in cultured embryos. Unbiased clustering analyses of blastomeres from such embryos reveal that the ability to respond to position emerges as early as the 8-cell stage during compaction and that altering the relative position of a blastomere within an embryo can alter its fate. Finally, we demonstrate that this response is lost upon inhibiting PKC signalling, linking it to the cell polarity. Our results pinpoint when during early embryogenesis cell specification decisions are initiated and show how blastomeres can sense their position in a polarity dependent manner to alter YAP localisation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/856161v1_ufig1.gif" ALT="Figure 1"> View larger version (35K): org.highwire.dtl.DTLVardef@845b46org.highwire.dtl.DTLVardef@18473ceorg.highwire.dtl.DTLVardef@cf0124org.highwire.dtl.DTLVardef@53fc8b_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗