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1. Individual reflectance of solar radiation confers a thermoregulatory benefit to dimorphic males bees (Centris pallida) using distinct microclimates

   https://doi.org/10.1371/journal.pone.0271250  

   Barrett, Meghan; O’Donnell, Sean (March 2023, PLOS ONE)

   Cini, Alessandro (Ed.)

   Incoming solar radiation (wavelengths 290–2500 nm) significantly affects an organism’s thermal balance via radiative heat gain. Species adapted to different environments can differ in solar reflectance profiles. We hypothesized that conspecific individuals using thermally distinct microhabitats to engage in fitness-relevant behaviors would show intraspecific differences in reflectance: we predicted individuals that use hot microclimates (where radiative heat gain represents a greater thermoregulatory challenge) would be more reflective across the entire solar spectrum than those using cooler microclimates. Differences in near-infrared (NIR) reflectance (700–2500 nm) are strongly indicative of thermoregulatory adaptation as, unlike differences in visible reflectance (400–700 nm), they are not perceived by ecological or social partners. We tested these predictions in maleCentris pallida(Hymenoptera: Apidae) bees from the Sonoran Desert. MaleC.pallidause alternative reproductive tactics that are associated with distinct microclimates: Large-morph males, with paler visible coloration, behave in an extremely hot microclimate close to the ground, while small-morph males, with a dark brown dorsal coloration, frequently use cooler microclimates above the ground near vegetation. We found that large-morph males had higher reflectance of solar radiation (UV through NIR) resulting in lower solar absorption coefficients. This thermoregulatory adaptation was specific to the dorsal surface, and produced by differences in hair, not cuticle, characteristics. Our results showed that intraspecific variation in behavior, particular in relation to microclimate use, can generate unique thermal adaptations that changes the reflectance of shortwave radiation among individuals within the same population. 

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2. Coming to the Caribbean—acclimation of Rhesus macaques ( Macaca mulatta ) at Cayo Santiago

   https://doi.org/10.1002/ajpa.24748  

   Francis, George; Wang, Qian (April 2023, American Journal of Biological Anthropology)

   Abstract ObjectivesTo investigate whether the Cayo Santiago, Puerto Rico (Latitude: 18.1564°N; temperature range 19°C to 32°C) rhesus macaque population has acclimated to their tropical island conditions since arriving from Lucknow, India (Latitude: 26.8470°N; temperature range 8°C to 41°C) in 1938. Materials and MethodsUsing the derived skeletal collection, measurements were taken of long bone lengths, diaphyseal circumference, and body weight using 635 (237 males and 398 females) skeletally mature individuals. Measurements sampled colony members born over a 51‐year time span at Cayo Santiago, from 1951 to 2002. ResultsResults demonstrated that body weights and diaphyseal circumferences significantly declined in both males and females. Long bone lengths relative to body weight and diaphyseal circumference also increased in females. Whereas body weight, long bone length and diaphyseal circumference declined at near parallel rates in males. DiscussionThe population has acclimated to homogenous, tropical, conditions of the Caribbean island since their arrival over 80 years ago. Trends in both sexes aligned with Bergmann's rule, though females displayed a greater decline in body weight, as well as greater affinity with Allen's rule, than did males. Buffering effects related to male competition may be responsible for this discrepancy. Overall, the Cayo Santiago populations, as shown over a significant period (1951–2002) of their history, have acclimated to their island conditions by decreasing in size and altering body proportions. 

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3. Group structure, but not dominance rank, predicts fecal androgen metabolite concentrations of wild male mountain gorillas ( Gorilla beringei beringei )

   https://doi.org/10.1002/ajp.23295  

   Rosenbaum, Stacy; Eckardt, Winnie; Stoinski, Tara S.; Umuhoza, Rose; Kuzawa, Christopher W.; Santymire, Rachel M. (July 2021, American Journal of Primatology)

   Abstract Androgens are important mediators of male‐male competition in many primate species. Male gorillas' morphology is consistent with a reproductive strategy that relies heavily on androgen‐dependent traits (e.g., extreme size and muscle mass). Despite possessing characteristics typical of species with an exclusively single‐male group structure, multimale groups with strong dominance hierarchies are common in mountain gorillas. Theory predicts that androgens should mediate their dominance hierarchies, and potentially vary with the type of group males live in. We validated the use of a testosterone enzyme immunoassay (T‐EIA R156/7, CJ Munro, UC‐Davis) for use with mountain gorilla fecal material by (1) examining individual‐level androgen responses to competitive events, and (2) isolating assay‐specific hormone metabolites via high‐performance liquid chromatography. Males had large (2.6‐ and 6.5‐fold), temporary increases in fecal androgen metabolite (FAM) after competitive events, and most captured metabolites were testosterone or 5α‐dihydrotestosterone‐like androgens. We then examined the relationship between males' dominance ranks, group type, and FAM concentrations. Males in single‐male groups had higher FAM concentrations than males in multimale groups, and a small pool of samples from solitary males suggested they may have lower FAM than group‐living peers. However, data from two different time periods (n = 1610 samples) indicated there was no clear relationship between rank and FAM concentrations, confirming results from the larger of two prior studies that measured urinary androgens. These findings highlight the need for additional research to clarify the surprising lack of a dominance hierarchy/androgen relationship in mountain gorillas. 

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4. Crithidia bombi can infect two solitary bee species while host survivorship depends on diet

   https://doi.org/10.1017/S0031182020002218  

   Figueroa, Laura L.; Grincavitch, Cali; McArt, Scott H. (April 2021, Parasitology)

   null (Ed.)

   Abstract Pathogens and lack of floral resources interactively impair global pollinator health. However, epidemiological and nutritional studies aimed at understanding bee declines have historically focused on social species, with limited evaluations of solitary bees. Here, we asked whether Crithidia bombi , a trypanosomatid gut pathogen known to infect bumble bees, could infect the solitary bees Osmia lignaria (females) and Megachile rotundata (males), and whether nutritional stress influenced infection patterns and bee survival. We found that C. bombi was able to infect both solitary bee species, with 59% of O. lignaria and 29% of M. rotundata bees experiencing pathogen replication 5–11 days following inoculation. Moreover, access to pollen resulted in O. lignaria living longer, although it did not influence M. rotundata survival. Access to pollen did not affect infection probability or resulting pathogen load in either species. Similarly, inoculating with the pathogen did not drive survival patterns in either species during the 5–11-day laboratory assays. Our results demonstrate that solitary bees can be hosts of a known bumble bee pathogen, and that access to pollen is an important contributing factor for bee survival, thus expanding our understanding of factors contributing to solitary bee health. 

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5. Facial and body colouration is linked to social rank in the African cichlid Astatotilapia burtoni

   https://doi.org/10.1101/2024.08.21.608989  

   Peroš, M; Chang, A; Martashvili, A; Alvarado, SG (August 2024, bioRxiv)

   TBD (Ed.)

   Animal colouration is fundamentally important for social communication within conspecifics to advertising threat to competitors or fitness to possible mates. Social status and animal colouration are covarying traits that are plastic in response to dynamic environments. In the African cichlid,Astatotilapia burtoni, body colouration and behaviour have been extensively reported to vary with social rank. However, the nature of the interaction between these two traits is poorly understood. We hypothesise that pigmentation patterns could be linked to the behavioural repertoires underlying social status and can be resolved to regions on the cichlid body plan. To test this hypothesis, we generated Territorial (T) and Non-territorial (NT) males and employed computer vision tools to quantify and visualise patterns/colour enrichment associated with stereotyped T/NT male behaviour. We report colour-behaviour interactions localised in specific areas of the body and face for two colour morphs illustrating a more nuanced view of social behaviour and pigmentation. Since behavioural and morphological variation are key drivers of selection in the East African Great Rift Lakes, we surmise our data may be translatable to other cichlid lineages and underline the importance of trait covariance in sexual selection and male competition. 

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