Host controls of within-host dynamics: insight from an invertebrate system (2021) Stewart Merrill et al., The American Naturalist. https://doi.org/10.1086/715355
Image Credit: Per Harald Olsen, NTNU, CC BY 2.0, Image Cropped
When it comes to understanding how parasites and pathogens spread, immune defenses may be an especially important factor. The immune system is the gatekeeper for parasites and pathogens (I’ll just use the term “pathogen” from here on out). Whether you are exposed to influenza, a parasitic worm, or a tick-borne bacterium, your immune response will determine the outcome of infection — either you will become infected (which benefits the pathogen’s reproduction) or you will not (which is a barrier to the pathogen’s reproduction). So now, picture a whole population of individuals. A room full of individuals with poor immune responses should result in more infections (and more transmission) than a room full of individuals with strong and robust immune defenses. By shaping the fate of pathogens, host immune defenses can shape transmission.
EDIT: This paper is one of many papers by Jonathan Pruitt which is currently under investigation for suspected data manipulation. More on that at the link below.
#PruittData and the Ethics of Data in Science
Leadership can play an important role of a population dynamics, but is it the strength of the leaders or the willingness of the followers that has more influence? (Image Credit: Bernard Dupont, CC BY-SA 2.0)
Selection for Collective Aggressiveness Favors Social Susceptibility in Social Spiders (2018) Pruitt et al., Current Biology, doi: 10.1016/j.cub.2017.11.038.
Socially-influential leaders can have a large effect on the actions of any group. Think of that one person in your life that everyone looks to when it’s time to make a decision; whether it’s something trivial like where to go for dinner, or something more important like whether or not to take that job on the other side of the country, these individuals make a large impact in their social circles. This can also be seen in the natural world, like the alpha of a wolf pack, or the matriarchs of an elephant troop or an orca pod. These focal individuals greatly influence the actions and success of their groups.
In order to determine not only how important these influential individuals are, but also how much the “social susceptibility” of the followers matters, the researchers in this paper used a species of social spider in two different habitat types. By using both arid and wet environments and analyzing both sides of the influence coin, this study was able to accurately determine the importance of both influencing and being influenced in different ecosystems.