Machine-learning model led design to experimentally test species thermal limits: The case of kissing bugs (Triatominae).

Species Distribution Modelling (SDM) determines habitat suitability of a species across geographic areas using macro-climatic variables; however, micro-habitats can buffer or exacerbate the influence of macro-climatic variables, requiring links between physiology and species persistence. Experimental approaches linking species physiology to micro-climate are complex, time consuming and expensive. E.g., what combination of exposure time and temperature is important for a species thermal tolerance is difficult to judge a priori. We tackled this problem using an active learning approach that utilized machine learning methods to guide thermal tolerance experimental design for three kissing-bug species: Triatoma infestans, Rhodnius prolixus, and Panstrongylus megistus (Hemiptera: Reduviidae: Triatominae), vectors of the parasite causing Chagas disease. As with other pathogen vectors, triatomines are well known to utilize micro-habitats and the associated shift in microclimate to enhance survival. Using a limited literature-collected dataset, our approach showed that temperature followed by exposure time were the strongest predictors of mortality; species played a minor role, and life stage was the least important. Further, we identified complex but biologically plausible nonlinear interactions between temperature and exposure time in shaping mortality, together setting the potential thermal limits of triatomines. The results from this data led to the design of new experiments with laboratory results that produced novel insights of the effects of temperature and exposure for the triatomines. These results, in turn, can be used to better model micro-climatic envelope for the species. Here we demonstrate the power of an active learning approach to explore experimental space to design laboratory studies testing species thermal limits. Our analytical pipeline can be easily adapted to other systems and we provide code to allow practitioners to perform similar analyses. Not only does our approach have the potential to save time and money: it can also increase our understanding of the links between species physiology and climate, a topic of increasing ecological importance.

Antiquity of postreproductive life: are there modern impacts on hunter-gatherer postreproductive life spans?

Female postreproductive life is a striking feature of human life history and there have been several recent attempts to account for its evolution. But archaeologists estimate that in the past, few individuals lived many postreproductive years. Is postreproductive life a phenotypic outcome of modern conditions, needing no evolutionary account? This article assesses effects of the modern world on hunter-gatherer adult mortality, with special reference to the Hadza. Evidence suggests that such effects are not sufficient to deny the existence of substantial life expectancy at the end of the childbearing career. Data from contemporary hunter-gatherers (Ache, !Kung, Hadza) match longevity extrapolated from regressions of lifespan on body and brain weight. Twenty or so vigorous years between the end of reproduction and the onset of significant senescence does require an explanation.