@article {68477,
	title = {Eco-evolutionary significance of "loners".},
	journal = {PLoS Biol},
	volume = {18},
	year = {2020},
	month = {03/2020},
	pages = {e3000642},
	abstract = {<p>Loners-individuals out of sync with a coordinated majority-occur frequently in nature. Are loners incidental byproducts of large-scale coordination attempts, or are they part of a mosaic of life-history strategies? Here, we provide empirical evidence of naturally occurring heritable variation in loner behavior in the model social amoeba Dictyostelium discoideum. We propose that Dictyostelium loners-cells that do not join the multicellular life stage-arise from a dynamic population-partitioning process, the result of each cell making a stochastic, signal-based decision. We find evidence that this imperfectly synchronized multicellular development is affected by both abiotic (environmental porosity) and biotic (signaling) factors. Finally, we predict theoretically that when a pair of strains differing in their partitioning behavior coaggregate, cross-signaling impacts slime-mold diversity across spatiotemporal scales. Our findings suggest that loners could be critical to understanding collective and social behaviors, multicellular development, and ecological dynamics in D. discoideum. More broadly, across taxa, imperfect coordination of collective behaviors might be adaptive by enabling diversification of life-history strategies.</p>
},
	keywords = {Biological Evolution, Dictyostelium, Models, Biological, Quorum Sensing, Spatio-Temporal Analysis, Stochastic Processes},
	issn = {1545-7885},
	doi = {10.1371/journal.pbio.3000642},
	author = {Rossine, Fernando W and Martinez-Garcia, Ricardo and Sgro, Allyson E and Gregor, Thomas and Tarnita, Corina E}
}
@article {68482,
	title = {Fitness tradeoffs between spores and nonaggregating cells can explain the coexistence of diverse genotypes in cellular slime molds.},
	journal = {Proc Natl Acad Sci U S A},
	volume = {112},
	year = {2015},
	month = {03/2015},
	pages = {2776-81},
	abstract = {<p>Cellular slime molds, including the well-studied Dictyostelium discoideum, are amoebae whose life cycle includes both a single-cellular and a multicellular stage. To achieve the multicellular stage, individual amoebae aggregate upon starvation to form a fruiting body made of dead stalk cells and reproductive spores, a process that has been described in terms of cooperation and altruism. When amoebae aggregate they do not perfectly discriminate against nonkin, leading to chimeric fruiting bodies. Within chimeras, complex interactions among genotypes have been documented, which should theoretically reduce genetic diversity. This is however inconsistent with the great diversity of genotypes found in nature. Recent work has shown that a little-studied component of D. discoideum fitness--the loner cells that do not participate in the aggregation--can be selected for depending on environmental conditions and that, together with the spores, they could represent a bet-hedging strategy. We suggest that in all cellular slime molds the existence of loners could resolve the apparent diversity paradox in two ways. First, if loners are accounted for, then apparent genotypic skew in the spores of chimeras could simply be the result of different investments into spores versus loners. Second, in an ecosystem with multiple local environments differing in their food recovery characteristics and connected globally via weak-to-moderate dispersal, coexistence of multiple genotypes can occur. Finally, we argue that the loners make it impossible to define altruistic behavior, winners or losers, without a clear description of the ecology.</p>
},
	keywords = {Dictyostelium, Ecosystem, Life Cycle Stages, Spores, Protozoan},
	issn = {1091-6490},
	doi = {10.1073/pnas.1424242112},
	author = {Tarnita, Corina E and Washburne, Alex and Martinez-Garcia, Ricardo and Sgro, Allyson E and Levin, Simon A}
}
