Variation in resource competition traits among Microcystis strains is affected by their microbiomes

Freshwater harmful algal blooms are often dominated by Microcystis,a phylogenetically cohesive group of cyanobacteria marked by extensive genetic and physiological diversity.We have previously shown that this genetic diversity and the presence of a microbiome of heterotrophic bacteria influences competitive interactions with eukaryotic phytoplankton.In this study,we sought to explain these observations by characterizing Monod equation parameters for resource usage(maximum growth rateμmax,half-saturation value for growth Ks,and quota)as a function of N and P levels for four strains(NIES-843,PCC 9701,PCC 7806[WT],and PCC 7806ΔmcyB)in presence and absence of a microbiome derived from Microcystis isolated from Lake Erie.Results indicated limited differences in maximum growth rates but more pronounced differences in half-saturation values among Microcystis strains.The largest impact of the microbiome was reducing the minimal nitrogen concentration sustaining growth and reducing half saturation values,with variable results depending on the Microcystis strain.Microcystis strains also differed from each other in their N and P quotas and the extent to which microbiome presence affected them.Our data highlight the importance of the microbiome in altering Microcystis-intrinsic traits,strain competitive hierarchies,and thus bloom dynamics.As quota,μmax,and Ks are commonly used in models for harmful algal blooms,our data suggest that model improvement may be possible by incorporating genotype dependencies of resource-use parameters.

Size-dependent flight capacity and propensity in a range-expanding invasive insect

For capital-breeding insects,all resources available for adult metabolic needs are accumulated during larval feeding.Therefore,body size at adult eclosion represents the total energetic capacity of the individual.For female capital breeders,body size is strongly correlated with lifetime fecundity,while in males,body size,which correlates with fitness,is less understood.In capital-breeding species with wingless,flightless,or dispersal-limited females,flight potential for male Lepidoptera has important implications for mate-finding and may be correlated with body size.At low population densities,failure to mate has been identified as an important Allee effect and can drive the success or failure of invasive species at range edges and in species of conservation concern.Th capital-breeding European subspecies of Lymantria dispar(L.),was introduced to North America in 1869 and now ranges across much of eastern North America.In L.dispar,females are flightless and mate-finding is entirely performed by males.We quantified male L.dispar flight capacity and propensity relative to morphological and physiological characteristics using fixed-arm flight mills.A range of male body sizes was produced by varying the protein content of standard artificial diets while holding other dietary components constant.Wing length,a proxy for body size,relative thorax mass,and forewing aspect were all important predictors of total flight distance and maximum speed.These results have important implications for mate-finding and invasion dynamics in L.dispar and may apply broadly to other capital-breeding insects.