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1. Developmental constraint shaped genome evolution and erythrocyte loss in Antarctic fishes following paleoclimate change

   Jacob M. Daane, JM; Auvinet, J; Stoebenau, A; Yergeau, D; Harris, MP; Detrich, HW (October 2020, PLOS genetics)

   null (Ed.)

   In the frigid, oxygen-rich Southern Ocean (SO), Antarctic icefishes (Channichthyidae; Notothenioidei) evolved the ability to survive without producing erythrocytes and hemoglo- bin, the oxygen-transport system of virtually all vertebrates. Here, we integrate paleoclimate records with an extensive phylogenomic dataset of notothenioid fishes to understand the evolution of trait loss associated with climate change. In contrast to buoyancy adaptations in this clade, we find relaxed selection on the genetic regions controlling erythropoiesis evolved only after sustained cooling in the SO. This pattern is seen not only within icefishes but also occurred independently in other high-latitude notothenioids. We show that one spe- cies of the red-blooded dragonfish clade evolved a spherocytic anemia that phenocopies human patients with this disease via orthologous mutations. The genomic imprint of SO cli- mate change is biased toward erythrocyte-associated conserved noncoding elements (CNEs) rather than to coding regions, which are largely preserved through pleiotropy. The drift in CNEs is specifically enriched near genes that are preferentially expressed late in erythropoiesis. Furthermore, we find that the hematopoietic marrow of icefish species retained proerythroblasts, which indicates that early erythroid development remains intact. Our results provide a framework for understanding the interactions between development and the genome in shaping the response of species to climate change. 

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2. Herbarium specimens reveal a constrained seasonal climate niche despite diverged annual climates across a wildflower clade

   https://doi.org/10.1073/pnas.2503670122  

   Bontrager, Megan; Worthy, Samantha J; Cacho, N Ivalú; Leventhal, Laura; Maloof, Julin N; Gremer, Jennifer R; Schmitt, Johanna; Strauss, Sharon Y (July 2025, Proceedings of the National Academy of Sciences)

   Quantifying species’ niches across a clade reveals how environmental tolerances evolve, and offers insights into present and future distributions. We use herbarium specimens to explore climate niche evolution across 14 annual species of theStreptanthus(s.l.) clade (Brassicaceae), which originated in deserts and diversified into cooler, moister areas. To understand how climate niches evolved, we used historical climate records to estimate each species’ 1) classic annual climate niche, averaged over specimen collection sites; 2) growing season niche, from estimated specimen germination date to collection date, averaged across specimens (specimen-specific niche); and 3) standardized seasonal niche based on average growing seasons of all species (clade-seasonal niche). In addition to estimating how phenological variation maps onto climate niche evolution, we explored how spatial refugia shape the climate experienced by species by 1) analyzing how field soil texture changes relative to the climate space that species occupy and 2) comparing soil water holding capacity from each specimen locality to that of surrounding areas. Specimen-specific niches exhibited less clade-wide variation in climatic water deficit (CWD) than did annual or clade-seasonal niches, and specimen-specific temperature niches showed no phylogenetic signal, in contrast to annual and clade-seasonal temperature niches. Species occupying cooler regions tracked hotter and drier climates by growing later into the summer, and by inhabiting refugia on drought-prone soils. These results underscore how phenological shifts, spatial refugia, and germination timing shape “lived” climate. Despite occupying a large range of annual climates, we found these species are constrained in the conditions under which they thrive. 

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3. Genomics of Secondarily Temperate Adaptation in the Only Non-Antarctic Icefish

   https://doi.org/10.1093/molbev/msad029  

   Rivera-Colón, Angel G; Rayamajhi, Niraj; Minhas, Bushra Fazal; Madrigal, Giovanni; Bilyk, Kevin T; Yoon, Veronica; Hüne, Mathias; Gregory, Susan; Cheng, C H; Catchen, Julian M (March 2023, Molecular Biology and Evolution)

   Kelley, Joanna (Ed.)

   Abstract White-blooded Antarctic icefishes, a family within the adaptive radiation of Antarctic notothenioid fishes, are an example of extreme biological specialization to both the chronic cold of the Southern Ocean and life without hemoglobin. As a result, icefishes display derived physiology that limits them to the cold and highly oxygenated Antarctic waters. Against these constraints, remarkably one species, the pike icefish Champsocephalus esox, successfully colonized temperate South American waters. To study the genetic mechanisms underlying secondarily temperate adaptation in icefishes, we generated chromosome-level genome assemblies of both C. esox and its Antarctic sister species, Champsocephalus gunnari. The C. esox genome is similar in structure and organization to that of its Antarctic congener; however, we observe evidence of chromosomal rearrangements coinciding with regions of elevated genetic divergence in pike icefish populations. We also find several key biological pathways under selection, including genes related to mitochondria and vision, highlighting candidates behind temperate adaptation in C. esox. Substantial antifreeze glycoprotein (AFGP) pseudogenization has occurred in the pike icefish, likely due to relaxed selection following ancestral escape from Antarctica. The canonical AFGP locus organization is conserved in C. esox and C. gunnari, but both show a translocation of two AFGP copies to a separate locus, previously unobserved in cryonotothenioids. Altogether, the study of this secondarily temperate species provides an insight into the mechanisms underlying adaptation to ecologically disparate environments in this otherwise highly specialized group. 

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4. Cool birds: facultative use by an introduced species of mechanical air conditioning systems during extremely hot outdoor conditions

   https://doi.org/10.1098/rsbl.2020.0813  

   Mills, Raegan; McGraw, Kevin J. (March 2021, Biology Letters)

   Rapid climate change across the globe is having dramatic effects on wildlife. Responses of organisms to shifting thermal conditions often include physiological and behavioural accommodations, but to date these have been largely viewed and studied as naturally evolved phenomena (e.g. heat avoidance, sweating, panting) and not necessarily as strategies where animals exploit other anthropogenic conditions or resources. Moreover, the degree to which native versus introduced species show thermal plasticity has generated much conservation and ecological interest. We previously have observed introduced rosy-faced lovebirds ( Agapornis roseicollis ) perching in the relief-air vents on building faces in the Phoenix, Arizona, USA, metropolitan area, but doing so only during summer. Here, we show that such vent-perching events are significantly associated with extreme outdoor summer temperatures (when daily local highs routinely exceed 40°C). In fact, the temperature threshold at which we detected lovebirds starting to perch in cool air vents mirrors the upper range of the thermoneutral zone for this species. These results implicate novel, facultative use of an anthropogenic resource—industrial air-conditioning systems—by a recently introduced species (within the last 35 years) to cool down and survive extremely hot conditions in this urban ‘heat-island' environment. 

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5. Metabolic plasticity of tropical and temperate dung beetles to increasing temperature variation

   Fleming, J Morgan; Marshall, Katie; Meidl, Timothy; Celi, Jorge; Sheldon, Kimberly S (March 2023, Integrative & Comparative Biology)

   Increasing temperature fluctuations associated with climate change are expected to have profound effects on species performance and fitness, but these effects might vary among organisms that evolved in different thermal environments. For instance, tropical species that have evolved in relatively stable thermal conditions may have limited capacity to cope with increasing temperature fluctuations compared to temperate species that evolved in more variable thermal conditions. We used dung beetles from tropical (Ecuador) and tem- 

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