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We describe the complete embryonic cell lineage of the marine nematode Pellioditis marina (Rhabditidae) up to somatic muscle contraction, resulting in the formation of 638 cells, of which 67 undergo programmed cell death. In comparison with Caenorhabditis elegans, the overall lineage homology is 95.5%; fate homology, however, is only 76.4%. The majority of the differences in fate homology concern nervous, epidermal, and pharyngeal tissues. Gut and, remarkably, somatic muscle is highly conserved in number and position. Partial lineage data from the slower developing Halicephalobus sp. (Panagrolaimidae) reveal a lineage largely, but not exclusively, built up of monoclonal sublineage blocs with identical fates, unlike the polyclonal fate distribution in C. elegans and P. marina. The fate distribution pattern in a cell lineage could be a compromise between minimizing the number of specification events by monoclonal specification and minimizing the need for migrations by forming the cells close at their final position. The latter could contribute to a faster embryonic development. These results reveal that there is more than one way to build a nematode.

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The free-living nematode Rhabditophanes sp. has recently been placed in a clade of animal parasites and may be a unique example of a reversal to a nonparasitic lifestyle. Detailed morphological analysis of the intestine reveals the unusual and unique structure of splitting microlamellae forming a meshwork with cavities along the entire intestinal tract. Secretion vesicles were observed along the whole tract and along the length of the lamellae. It is suggested that these lamellae are adaptations to a different digestive strategy where low food availability and a low absorption surface are compensated for by maximizing the nutrient uptake efficiency along the entire length of the intestine. The likely reversal to a free-living life cycle may have caused drastic changes in diet, providing the necessary driving forces to such morphological changes.

Because of the high number of species and its ancient roots in evolution, the phylum Nematoda is well suited for comparative embryonic study. Using 4D microscopy we have reconstructed the embryonic lineages of several nematodes. This allows us to identify changing developmental strategies in the phylum Nematoda. Generally there has been a shift in the phylum from a non-determined, non-strict development to a faster, highly determined embryonic development. En raison du nombre élevé d’espèces et de ses racines anciennes dans l’évolution, le phylum Nematoda est bien approprié à des études d’embryologie comparée. A l’aide d’un microscope 4D, les lignages embryonnaires de plusieurs nématodes ont été reconstruits. Cela nous a permis d’identifier les modifications de stratégie développementales dans le phylum. Généralement, il y a eu un changement dans le phylum depuis un développement non déterminé et non précis jusqu’à un développement embryonnaire très rapide et hautement déterminé.

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Meteorological stations are rare in the tropics and satellite products often do not perform optimal. This leads to uncertainty in modelled regional climatic trends and may lead to opposing trends in prediction of future climate. This is particularly problematic for the Congo basin, where station coverage decreased significantly during the last few decades. Therefore, here we present a newly digitised dataset of daily temperature and precipitation from the Yangambi biosphere reserve, covering the period 1960 - 2020 (61 years) and located in the heart of the Congo basin. Our results confirm a long-term increase in temperature and temperature extremes since the 1960s, with strong upward trends since the early 1990s. Our results also indicate a drying trend for the dry season and intensification of the wet season since the early 2000s. Ongoing warming and increasing precipitation seasonality and intensity already has a significant impact on crop yields in Yangambi. This calls for urgent development of climate-smart and dynamic agriculture and agroforestry systems. We conclude that systematic digitization and climate recording in the Congo basin will be critical to improve much-needed gridded benchmark datasets of climatic variables.