The biogeographic differentiation of algal microbiomes in the upper ocean from pole to pole

Eukaryotic phytoplankton are responsible for at least 20% of annual global carbon fixation. Their diversity and activity are shaped by interactions with prokaryotes as part of complex microbiomes. Although differences in their local species diversity have been estimated, we still have a limited understanding of environmental conditions responsible for compositional differences between local species communities on a large scale from pole to pole. Here, we show, based on pole-to-pole phytoplankton metatranscriptomes and microbial rDNA sequencing, that environmental differences between polar and non-polar upper oceans most strongly impact the large-scale spatial pattern of biodiversity and gene activity in algal microbiomes. The geographic differentiation of co-occurring microbes in algal microbiomes can be well explained by the latitudinal temperature gradient and associated break points in their beta diversity, with an average breakpoint at 14 °C ± 4.3, separating cold and warm upper oceans. As global warming impacts upper ocean temperatures, we project that break points of beta diversity move markedly pole-wards. Hence, abrupt regime shifts in algal microbiomes could be caused by anthropogenic climate change.

Geographic differentiation of adaptive phenological traits of barnyardgrass populations (Echinochloa crus-galli)

In Central Europe, barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], has been originally common in humid lowland areas. As a result of the introduction of new crops and farming practices, in the northwest Carpathians, E. crus-galli has spread from lowland (< 200 m altitude) to highland (> 400 m altitude) areas. We collected seed samples from local populations lying at a distance of approximately 5 km from each other and lined up along transects following the flows of two rivers. The rivers first flow through the valleys separated by mountain ridges and eventually flow into a common lowland. After ripening, the seeds of all populations were germinated at 25°C under long-day conditions. Only the seeds of some lowland populations germinated up to 75 percentage. The frequency of germinated seeds decreased with the altitude of population origin, and above 200 m a.s.l., germination was mostly zero. We then studied the phenological and morphological differentiation of plants from the original (lowland) and recently occupied (highland) areas. Seeds of the lowest and the highest localities lying on the transect of each river were sown in a common garden experiment. In plants from the highland localities, heading and seed dispersal were earlier, while tiller height and tiller mass were lower than in plants from the lowland localities. Seed mass produced per tiller in the lowland and highland plants was similar, and, as a result, highland plants allocated a larger proportion of body mass to seed production than did lowland plants. Echinochloa crus-galli populations from highland localities thus produce their progeny earlier and at a lower energy cost than populations from lowland localities. The plasticity of phenological characters likely facilitated adaptation during E. crus-galli spread from lowlands to highlands. Similar adaptations in plant phenology may contribute to the spread of E. crus-galli in other geographic areas.

Philippine bats of the genus Kerivoula (Chiroptera: Vespertilionidae): Overview and assessment of variation in K. pellucida and K. whiteheadi

Bats of the genus Kerivoula (Mammalia, Chiroptera) are widespread in the Philippines with four reported species, but have been poorly known due to a paucity of specimens. We provide the first molecular phylogeny for Philippine Kerivoula, which supports the existence of four distinct clades that we treat as species (K. hardwickii, K. papillosa, K. pellucida, and K. whiteheadi); these four overlap broadly geographically. Each of these may be recognized on the basis of cytochrome b sequences and external and craniodental morphology. Detailed examination of K. pellucida shows little geographic differentiation within the Philippines, but they differ subtly from those on the Sunda Shelf. We consider K. whiteheadi to be composed of four recognizable clades, each restricted to a geographic region within the Philippines. We consider K. bicolor, from peninsular Thailand, and K. pusilla, from Borneo, to be distinct from K. whiteheadi. Our data indicate the presence of two species within the Philippines currently lumped as K. hardwickii; further study of these is needed. A calibrated phylogeny suggests that Kerivoula began arriving in the Philippines about 10 MYA, with each of the four current lineages arriving independently.