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1. Life cycle complexity and body mass drive erratic changes in climate vulnerability across ontogeny in a seasonally migrating butterfly

   https://doi.org/10.1093/conphys/coad058  

   Medina-Báez, Osmary A; Lenard, Angie; Muzychuk, Rut A; da_Silva, Carmen_R B; Diamond, Sarah E (January 2023, Conservation Physiology)

   Tomlinson, Sean (Ed.)

   Abstract Physiological traits are often used for vulnerability assessments of organismal responses to climate change. Trait values can change dramatically over the life cycle of organisms but are typically assessed at a single developmental stage. Reconciling ontogenetic changes in physiological traits with vulnerability assessments often reveals early life-stage vulnerabilities. The degree to which ontogenetic changes in physiological traits are due to changes in body mass over development versus stage-specific responses determines the degree to which mass can be used as a proxy for vulnerability. Here, we use the painted lady butterfly, Vanessa cardui, to test ontogenetic changes in two physiological traits, the acute thermal sensitivity of routine metabolic rate (RMR Q10) and the critical thermal maximum (CTmax). RMR Q10 generally followed ontogenetic changes in body mass, with stages characterized by smaller body mass exhibiting lower acute thermal sensitivity. However, CTmax was largely decoupled from ontogenetic changes in body mass. In contrast with trends from other studies showing increasing vulnerability among progressively earlier developmental stages, our study revealed highly erratic patterns of vulnerability across ontogeny. Specifically, we found the lowest joint-trait vulnerability (both RMR Q10 and CTmax) in the earliest developmental stage we tested (3rd instar larvae), the highest vulnerabilities in the next two developmental stages (4th and 5th instar larvae), and reduced vulnerability into the pupal and adult stages. Our study supports growing evidence of mechanistic decoupling of physiology across developmental stages and suggests that body mass is not a universal proxy for all physiological trait indicators of climate vulnerability. 

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2. Does a complex life cycle affect adaptation to environmental change? Genome-informed insights for characterizing selection across complex life cycle

   https://doi.org/10.1098/rspb.2021.2122  

   Albecker, Molly A.; Wilkins, Laetitia G.; Krueger-Hadfield, Stacy A.; Bashevkin, Samuel M.; Hahn, Matthew W.; Hare, Matthew P.; Kindsvater, Holly K.; Sewell, Mary A.; Lotterhos, Katie E.; Reitzel, Adam M. (December 2021, Proceedings of the Royal Society B: Biological Sciences)

   Complex life cycles, in which discrete life stages of the same organism differ in form or function and often occupy different ecological niches, are common in nature. Because stages share the same genome, selective effects on one stage may have cascading consequences through the entire life cycle. Theoretical and empirical studies have not yet generated clear predictions about how life cycle complexity will influence patterns of adaptation in response to rapidly changing environments or tested theoretical predictions for fitness trade-offs (or lack thereof) across life stages. We discuss complex life cycle evolution and outline three hypotheses—ontogenetic decoupling, antagonistic ontogenetic pleiotropy and synergistic ontogenetic pleiotropy—for how selection may operate on organisms with complex life cycles. We suggest a within-generation experimental design that promises significant insight into composite selection across life cycle stages. As part of this design, we conducted simulations to determine the power needed to detect selection across a life cycle using a population genetic framework. This analysis demonstrated that recently published studies reporting within-generation selection were underpowered to detect small allele frequency changes (approx. 0.1). The power analysis indicates challenging but attainable sampling requirements for many systems, though plants and marine invertebrates with high fecundity are excellent systems for exploring how organisms with complex life cycles may adapt to climate change. 

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3. Different tools for different trades: contrasts in specialized metabolite chemodiversity and phylogenetic dispersion in fruit, leaves, and roots of the neotropical shrubs Psychotria and Palicourea (Rubiaceae)

   https://doi.org/10.1111/plb.70013  

   Schneider, G F; Beckman, N G (August 2025, Plant Biology)

   Abstract Plants produce an astonishingly diverse array of specialized metabolites. A crucial step in understanding the origin of such chemodiversity is describing how chemodiversity manifests across the spatial and ontogenetic scales relevant to plant–biotic interactions.Focusing on 21 sympatric species ofPsychotriaandPalicourea sensu lato(Rubiaceae), we describe patterns of specialized metabolite diversity across spatial and ontogenetic scales using a combination of field collections, untargeted metabolomics, and ecoinformatics. We compare α, β, and γ diversity of specialized metabolites in expanding leaves, unripe pulp, immature seed, ripe pulp, mature seed, and fine roots.Within species, fruit tissues from across ontogenetic stages had ≥α diversity than leaves, and ≤β diversity than leaves. Pooled across species, fruit tissues and ontogenetic stages had the highest γ diversity of all organs, and fruit tissues and ontogenetic stages combined had a higher incidence of organ‐specific mass spectral features than leaves. Roots had ≤α diversity than leaves and the lowest β and γ diversity of all organs. Phylogenetic correlations of chemical distance varied by plant organ and chemical class.Our results describe patterns of specialized metabolite diversity across organs and species and provide support for organ‐specific contributions to plant chemodiversity. This study contributes to the growing understanding within plant evolutionary ecology of the biological scales of specialized metabolite diversification. Future studies combining our data on specialized metabolite diversity with biotic interaction data and experiments can test existing hypotheses on the roles of ecological interactions in the evolution of chemodiversity. 

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4. Are endocasts good proxies for brain size and shape in archosaurs throughout ontogeny?

   https://doi.org/10.1111/joa.12918  

   Watanabe, Akinobu; Gignac, Paul M.; Balanoff, Amy M.; Green, Todd L.; Kley, Nathan J.; Norell, Mark A. (December 2018, Journal of Anatomy)

   Abstract Cranial endocasts, or the internal molds of the braincase, are a crucial correlate for investigating the neuroanatomy of extinct vertebrates and tracking brain evolution through deep time. Nevertheless, the validity of such studies pivots on the reliability of endocasts as a proxy for brain morphology. Here, we employ micro‐computed tomography imaging, including diffusible iodine‐based contrast‐enhancedCT, and a three‐dimensional geometric morphometric framework to examine both size and shape differences between brains and endocasts of two exemplar archosaur taxa – the American alligator (Alligator mississippiensis) and the domestic chicken (Gallus gallus). With ontogenetic sampling, we quantitatively evaluate how endocasts differ from brains and whether this deviation changes during development. We find strong size and shape correlations between brains and endocasts, divergent ontogenetic trends in the brain‐to‐endocast correspondence between alligators and chickens, and a comparable magnitude between brain–endocast shape differences and intraspecific neuroanatomical variation. The results have important implications for paleoneurological studies in archosaurs. Notably, we demonstrate that the pattern of endocranial shape variation closely reflects brain shape variation. Therefore, analyses of endocranial morphology are unlikely to generate spurious conclusions about large‐scale trends in brain size and shape. To mitigate any artifacts, however, paleoneurological studies should consider the lower brain–endocast correspondence in the hindbrain relative to the forebrain; higher size and shape correspondences in chickens than alligators throughout postnatal ontogeny; artificially ‘pedomorphic’ shape of endocasts relative to their corresponding brains; and potential biases in both size and shape data due to the lack of control for ontogenetic stages in endocranial sampling. 

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5. Size Matters: An Evaluation of the Molecular Basis of Ontogenetic Modifications in the Composition of Bothrops jararacussu Snake Venom

   https://doi.org/10.3390/toxins12120791  

   Freitas-de-Sousa, Luciana A.; Nachtigall, Pedro G.; Portes-Junior, José A.; Holding, Matthew L.; Nystrom, Gunnar S.; Ellsworth, Schyler A.; Guimarães, Noranathan C.; Tioyama, Emilly; Ortiz, Flora; Silva, Bruno R.; et al (December 2020, Toxins)

   null (Ed.)

   Ontogenetic changes in venom composition have been described in Bothrops snakes, but only a few studies have attempted to identify the targeted paralogues or the molecular mechanisms involved in modifications of gene expression during ontogeny. In this study, we decoded B. jararacussu venom gland transcripts from six specimens of varying sizes and analyzed the variability in the composition of independent venom proteomes from 19 individuals. We identified 125 distinct putative toxin transcripts, and of these, 73 were detected in venom proteomes and only 10 were involved in the ontogenetic changes. Ontogenetic variability was linearly related to snake size and did not correspond to the maturation of the reproductive stage. Changes in the transcriptome were highly predictive of changes in the venom proteome. The basic myotoxic phospholipases A2 (PLA2s) were the most abundant components in larger snakes, while in venoms from smaller snakes, PIII-class SVMPs were the major components. The snake venom metalloproteinases (SVMPs) identified corresponded to novel sequences and conferred higher pro-coagulant and hemorrhagic functions to the venom of small snakes. The mechanisms modulating venom variability are predominantly related to transcriptional events and may consist of an advantage of higher hematotoxicity and more efficient predatory function in the venom from small snakes. 

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