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Recognising that species interact across a range of spatial scales, we explore how landscape structure interacts with temperature to influence persistence. Specifically, we recognise that few studies indicate thermal shifts as the proximal cause of species extinctions; rather, species interactions exacerbated by temperature result in extinctions. Using microcosm‐based experiments, as models of larger landscape processes, we test hypotheses that would be problematic to address through field work. A text‐book predator–prey system (the ciliates Didinium and Paramecium) was used to compare three landscapes: an unfragmented landscape subjected to uniform temperatures (10, 20, 30°C); a fragmented landscape (potentially hosting metapopulations) subjected to these three temperatures; and a fragmented landscape subjected to a spatial temperature gradient (∼ 10 to 30°C) – despite the prevalence of natural temperature ecoclines this is the first time such an analysis has been conducted. Initial thermal response‐analysis (growth, mortality, and movement measured between 10 and 30°C) suggested that as temperature increased, the predator might drive the prey to extinction. Thermal preferences (measured at 5 temperatures between 10 and 30°C), indicated that both predator and prey preferred warmer temperatures, with the predator exhibiting the stronger preference, suggesting that cooler regions might act as a prey‐refuge. The landscape level observations, however, did not entirely support the predictions. First, in the unfragmented landscape, increased temperature led to extinctions, but at the highest temperature (where the predator growth can be reduced) the prey survived. Second, at high temperatures the fragmented landscape failed to host metapopulations that would allow predator–prey persistence. Third, the thermal ecocline did not provide heterogeneity that improved stability; rather it forced both species to occupy a smaller realized space, leading toward extinctions. These findings reveal that temperature‐impacted rates and temperature preferences combine to drive predator–prey dynamics and persistence across landscapes.

The virulence of Vibrio parahaemolyticus is variable depending on its virulence determinants. A V. parahaemolyticus strain, in which the virulence is governed by the pirA and pirB genes, can cause acute hepatopancreatic necrosis disease (AHPND) in shrimps. Some V. parahaemolyticus that are non-AHPND strains also cause shrimp diseases and result in huge economic losses, while their pathogenicity and pathogenesis remain unclear. In this study, a non-AHPND V. parahaemolyticus , TJA114, was isolated from diseased Penaeus vannamei associated with a high mortality. To understand its virulence and adaptation to the external environment, whole-genome sequencing of this isolate was conducted, and its phenotypic profiles including pathogenicity, growth characteristics and nutritional requirements were investigated. Shrimps following artificial infection with this isolate presented similar clinical symptoms to the naturally diseased ones and generated obvious pathological lesions. The growth characteristics indicated that the isolate TJA114 could grow well under different salinity (10–55 p.p.t.), temperature (23–37 °C) and pH (6–10) conditions. Phenotype MicroArray results showed that this isolate could utilize a variety of carbon sources, amino acids and a range of substrates to help itself adapt to the high hyperosmotic and alkaline environments. Antimicrobial-susceptibility test showed that it was a multidrug-resistant bacterium. The whole-genomic analysis showed that this V. parahaemolyticus possessed many important functional genes associated with multidrug resistance, stress response, adhesions, haemolysis, putative secreted proteases, dedicated protein secretion systems and a variety of nutritional metabolic mechanisms. These annotated functional genes were confirmed by the phenotypic profiles. The results in this study indicated that this V. parahaemolyticus isolate possesses a high pathogenicity and strong environmental adaptability.

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Ciliated protists are among the oldest unicellular organisms with a heterotrophic lifestyle and share a common ancestor with Plantae. Unlike any other eukaryotes, there are two distinct nuclei in ciliates with separate germline and somatic cell functions. Here, we assembled a near complete macronuclear genome of Fabrea salina, which belongs to one of the oldest clades of ciliates. Its extremely minimized genome (18.35 Mb) is the smallest among all free-living heterotrophic eukaryotes and exhibits typical streamlined genomic features, including high gene density, tiny introns and shrinkage of gene paralogs. Gene families involved in hypersaline stress resistance, DNA replication proteins and mitochondrial biogenesis are expanded, and the accumulation of phosphatidic acid may play an important role in resistance to high osmotic pressure. We further investigated the morphological and transcriptomic changes in the macronucleus during sexual reproduction and highlighted the potential contribution of macronuclear residuals to this process. We believe that the minimized genome generated in this study provides novel insights into the genome streamlining theory and will be an ideal model to study the evolution of eukaryotic heterotrophs.