Fig. 2: Experimental evolution of thermal niches and life history in seed beetles.

Dryland legumes are nutritionally rich, drought tolerant and resilient to harsh weather^11,140 and provide subsistence for more than half a billion people in the driest regions of the world¹¹. However, these crops suffer substantial losses from seed beetles¹⁴⁰. To investigate how genetic adaptation to climate change might shape the impact of seed beetles on legume crops, we performed large-scale phenotyping of long-term experimental evolution lines of C. maculatus. Populations from three geographic locations (Brazil, square; California, circle; and Yemen, triangle) were sampled and allowed to adapt to common laboratory conditions for ca. 200 generations before experimental evolution. Four replicate populations were created per genetic background and split between the two evolution regimes (23 °C—cold, and 35 °C—hot), while the original ancestor remained at the benign temperature (29 °C). Experimental evolution proceeded over 90 and 130 generations for the cold (blue) and hot (red) adapted populations. During this time, the ancestors went through 130 generations of evolution. To provide molecular evidence for a temperature-dependent trade-off between maintenance and reproduction, gene expression was measured in both evolved and ancestral lines after 80−125 generations of evolution. After 40 (cold adapted) and 60 (hot adapted) generations, life-history adaptation was assessed in a common garden experiment. This data was complemented in generations 90 (cold lines) and 130 (hot Lines and ancestors). Life-history traits were measured in the three ancestors after 120 generations of evolution. Following 80−125 generations of experimental evolution, the host consumption of all lines and ancestors was scored in a common garden to assess how life-history evolution under simulated climate change had shaped the agricultural footprint left by C. maculatus. Photo-credit seed beetles: Johanna Liljestrand Rönn. The world map was made using the R packages ggplot2¹⁴¹ and ggthemes¹⁴².