High speciation rate of niche specialists in hot springs

Abstract

Ecological and evolutionary processes simultaneously regulate microbial diversity, but the evolutionary processes and their driving forces remain largely unexplored. Here we investigated the ecological and evolutionary characteristics of microbiota in hot springs spanning a broad temperature range (54.8–80 °C) by sequencing the 16S rRNA genes. Our results demonstrated that niche specialists and niche generalists are embedded in a complex interaction of ecological and evolutionary dynamics. On the thermal tolerance niche axis, thermal (T) sensitive (at a specific temperature) versus T-resistant (at least in five temperatures) species were characterized by different niche breadth, community abundance and dispersal potential, consequently differing in potential evolutionary trajectory. The niche-specialized T-sensitive species experienced strong temperature barriers, leading to completely species shift and high fitness but low abundant communities at each temperature (“home niche”), and such trade-offs thus reinforced peak performance, as evidenced by high speciation across temperatures and increasing diversification potential with temperature. In contrast, T-resistant species are advantageous of niche expansion but with poor local performance, as shown by wide niche breadth with high extinction, indicating these niche generalists are “jack-of-all-trades, master-of-none”. Despite of such differences, the T-sensitive and T-resistant species are evolutionarily interacted. Specifically, the continuous transition from T-sensitive to T-resistant species insured the exclusion probability of T-resistant species at a relatively constant level across temperatures. The co-evolution and co-adaptation of T-sensitive and T-resistant species were in line with the red queen theory. Collectively, our findings demonstrate that high speciation of niche specialists could alleviate the environmental-filtering-induced negative effect on diversity.

Patterns of bacterial generalists and specialists in lakes and reservoirs along a latitudinal gradient

“…This raises a fascinating question about the coexistence of bacterial taxa within generalists or specialists, which – for over 50 years – has been a major issue in ecological theory, where the number of species often appears to exceed the available niches, a phenomenon commonly known as ‘The paradox of the plankton’ (Hutchinson, 1961). The coexistence of bacterial taxa between generalists and specialists can be influenced by different strategies, such as intra‐specific variation, dormancy potential and evolutionary potential (He et al, 2023; Xu, Luo, et al, 2022; Yang et al, 2023). However, bacterial taxa within generalists or specialists have similar ecological strategies, but how they coexist remains unclear.…”

Antarctic geothermal soils exhibit an absence of regional habitat generalist microorganisms

“…We note that many thermophilic habitat generalists have been identified before, even along strong environmental gradients, e.g. (21,(60)(61)(62), so an absence of habitat generalists in our data set is surprising, although many thermophiles tend to be habitat specialists for temperature (20,45,63).…”

Large scale exploration reveals rare taxa as key members shaping microbial assembly in alkaline lake sediments

“…Specifically, we found that the microbial assemblage strategies of both abundant and rare taxa were influenced by environmental factors, consequently formed distinct geographical patterns across the saline lake region of northwestern China. While several studies focused on generalists and specialists in microbial communities 54,59,60 , our study investigated abundant and rare taxa following the methods used in a hot spring study 61 to dissect the ecological roles of microbial communities under different niches. We also uncovered that rare taxa act as keystone species in the communities, exhibiting wide adaptation across a large geographical scale.…”