Symbiont-bearing benthic foraminifera, like corals, rely on endosymbionts for growth and nutrition and experience bleaching under heat stress. , found in tropical and subtropical waters, hosts a diverse range of endosymbionts belonging to Symbiodiniaceae. We examined the thermal tolerance of the Red Sea population, which is the source of an established, invasive population of in the Eastern Mediterranean. The Red Sea population is expected to exhibit enhanced thermotolerance, potentially due to its greater variety of endosymbionts. We conducted temperature-manipulation experiments, measuring calcification rates and net photosynthesis, evaluating the thermotolerance of and its endosymbionts. We also analyzed the diversity of Symbiodiniaceae by sequencing the internal transcribed spacer 2 (ITS2). Our results show that exposure to 35°C initially induced stress in the endosymbionts during the first week; however, net photosynthesis gradually recovered in subsequent weeks. In contrast, host calcification rates remained low at 35°C, though not completely inhibited. Amplicon sequencing revealed that by the end of the experiment, a single ITS2 type, belonging to Symbiodiniaceae and initially present in field-collected specimens, became dominant in cultured individuals. Because this type became dominant across all temperature treatments, the observed shift likely reflects a response to laboratory conditions rather than direct thermal selection. Consequently, although the recovery at 35°C is consistent with acclimatory physiological responses, it does not provide direct evidence for symbiont-specific acclimation. Our findings suggest that holobiont physiological recovery and symbiont shuffling under laboratory conditions may contribute to the resilience of in warming oceans.

The mechanisms by which novel differentiation pathways evolve to produce new cell types are still not fully understood. Chromatophores, the pigmented cells in the skin, offer an ideal paradigm because each type independently develops from neural crest cells to produce a distinct colour using well-characterised biosynthetic pathways. Here we show, using single-cell gene expression analyses, that canonical chromatophores develop in the embryonic skin of corn snakes and bearded dragon lizards. Yet, we identify previously undescribed chromatophore subtypes in the bearded dragon. These populations co-express progenitor and mature markers and possibly contribute to embryonic skin patterning, as revealed by whole-mount in situ hybridisation. Comparative analyses uncover that while mature chromatophores show cross-species similarity reflecting shared pigmentary function, progenitor states differ in transcription factor usage, including species-specific deployment of MITF, PAX7, and TFEC. Integration with teleost and amphibian datasets confirms that diversification of pigmentation arises through distinct progenitor trajectories converging on similar mature states.

Symbiont-bearing benthic foraminifera, like corals, rely on endosymbionts for growth and nutrition and experience bleaching under heat stress. Sorites orbiculus, found in tropical and subtropical waters, hosts a diverse range of endosymbionts belonging to Symbiodiniaceae. We examined the thermal tolerance of the Red Sea population, which is the source of an established, invasive population of S. orbiculus in the Eastern Mediterranean. The Red Sea population is expected to exhibit enhanced thermotolerance, potentially due to its greater variety of endosymbionts. We conducted temperature-manipulation experiments, measuring calcification rates and net photosynthesis, evaluating the thermotolerance of S. orbiculus and its endosymbionts. We also analyzed the diversity of Symbiodiniaceae by sequencing the internal transcribed spacer 2 (ITS2). Our results show that exposure to 35°C initially induced stress in the endosymbionts during the first week; however, net photosynthesis gradually recovered in subsequent weeks. In contrast, host calcification rates remained low at 35°C, though not completely inhibited. Amplicon sequencing revealed that by the end of the experiment, a single ITS2 type, belonging to Symbiodiniaceae Clade F2 and initially present in field-collected specimens, became dominant in cultured individuals. Because this type became dominant across all temperature treatments, the observed shift likely reflects a response to laboratory conditions rather than direct thermal selection. Consequently, although the recovery at 35°C is consistent with acclimatory physiological responses, it does not provide direct evidence for symbiont-specific acclimation. Our findings suggest that holobiont physiological recovery and symbiont shuffling under laboratory conditions may contribute to the resilience of S. orbiculus in warming oceans.

The spatial patterning of mammalian hair follicle precursors in embryonic skin is most commonly studied in the laboratory mouse (), where new follicles form equidistantly from preexisting ones in successive waves. This simple geometric rule has been effectively described as emerging from an expansion-induction process. However, such a description is incompatible with more recent developmental data indicating instead that scale, feather, and hair placodes self-organize through reaction-diffusion-chemotaxis cell interactions involving epidermal and dermal signaling. Here, we suggest that the chemotactic component of this framework suffices to describe the dynamics of placode insertion in two mammalian species that exhibit drastically different patterns. More specifically, we investigate a continuum dynamical model capturing interactions between motile dermal mesenchymal cells and an epidermal chemoattractant, embedded in a two-dimensional, isotropically expanding domain representing the growing embryonic skin. Through numerical simulations, mathematical analysis, and comparison to experimental developmental data, we first show that the chemotaxis model gives rise to the effective geometric rule that initially justified the development of the expansion-induction model in the laboratory mouse. Second, we show that the strikingly regular hair placode pattern in the spiny mouse ()-with long-range order, specific orientation and anisotropies-is not generated by an expansion-induction mechanism, but is recapitulated by an anisotropic chemotaxis model combined with experimentally observed anisotropic growth. Overall, our findings reveal that variation in the chemotactic component of the corresponding self-organizational system might be a key determinant of interspecific differences in hair placode patterning dynamics and resulting spatial organizations.

Sex Peptide (SP) induces many of the most studied female post-mating responses (PMRs) in Drosophila melanogaster but has been lost multiple times in the Drosophila genus. We decided to explore the PMRs of Drosophila hydei, a species without SP. Our work shows that the PMRs in D. hydei are somewhat different than those found in D. melanogaster and may be the consequence of a selection for producing a reduced number of extremely long sperm. D. hydei females lack the substantial post-mating increase in egg production found in D. melanogaster, mostly displaying only a brief induction in the laying of stored eggs. Mated females do not show a reduction in lifespan that has been linked to changes in metabolism and egg production. To further explore the reproductive biology of this species, we performed sperm competition experiments that suggest that D. hydei females may select sperm based on characteristics linked to changes in seminal fluid proteins. This was further investigated by examining the structure of the seminal fluid-producing accessory glands and the egg laying PMRs in different Drosophila species. Finally, video-based monitoring of D. hydei females was used to uncover novel changes in circadian rhythm and light preference in mated females.