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Results for “coadaptation”

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PubMed2026

Disruption of mitonuclear coadaptation and compensatory evolution after an extreme dietary shift in carnivorous butterflies.

Mitochondrial function depends on tight coordination between mitochondrial and nuclear genomes, which requires long-term coevolution to maintain mitonuclear coadaptation. While mitonuclear incompatibility is typically studied in the context of hybridization, other evolutionary scenarios that may disrupt coadaptation between the two genomes remain less explored. Here, we propose that extreme ecological niche shifts may disrupt mitonuclear coadaptation, which we test in carnivorous Miletinae butterflies with an extreme dietary transition. By generating high-quality genome assemblies, we found that Miletinae exhibit extensive chromosomal rearrangements. Comparative phylogenomic analyses revealed a striking asymmetric mitonuclear evolutionary response: Miletinae exhibit elevated mitochondrial nucleotide substitution rates compared to phytophagous relatives, whereas nuclear rates remain stable. This shift reverses the typical lepidopteran pattern where nuclear rates exceed mitochondrial rates. Interestingly, this mitochondrial acceleration is driven primarily by relaxed purifying selection rather than positive selection. To sustain mitochondrial function, the nuclear genome of Miletinae underwent pervasive, multilayered compensatory evolution. We detected strong signatures of positive selection and accelerated evolution in nuclear genes directly interacting with mitochondrial components across oxidative phosphorylation (OXPHOS) complexes, the mitochondrial translation, and replication and transcription machinery. Furthermore, this nuclear compensatory response extends to systems governing mitochondrial homeostasis, including protein quality control and RNA degradation and stabilization. Our results support a model in which extreme ecological transitions can disrupt ancestral mitonuclear coadaptation and promote the emergence of a new coadapted state through systemic nuclear compensation. This study broadens the conceptual framework of mitonuclear coevolution and highlights its role in facilitating evolutionary persistence after major ecological shifts.

Animals↗

PubMed1976

Evidence for coadaptation: negative correlation between lethal genes and polymorphic inversions in Drosophila melanogaster.

Through examination of all available data on lethal and inversion frequencies on the second chromosome in natural populations of Drosophila melanogaster, we have discovered that there is a clear negative correlation between the two quantities. Lethal genes are located more densely on the regions of standard gene arrangement than the inverted regions, and this accounts for the negative correlation. To reveal the underlying mechanism of the phenomena, we have carried out an experiment and found that effect of EMS-induced mutations on the inversion-carrying chromosome is more severe than that on the standard chromosome. We interpret these results as evidence for coadaptation or position-effect within the inversion chromosomes. New mutations within the coadapted gene complex are quickly eliminated from the population and polymorphic inversions are kept free of mutants through selective elimination.

Animals↗

PubMed1977

Mechanism of a case of genetic coadaptation in populations of Drosophila melanogaster.

A cryptic polymorphism found in natrual populations of Drosophila melanogaster has been examined in an artificial population maintained for over 200 generations. The polymorphism is selected because it is insensitive to the segregation distorter phenomenon, and it thereby largely preserves the Mendelian rules of segregation. Segregation distorter chromosomes and the cryptic polymorphism form part of a coadapted complex which is associated with linkage disequilibrium in natrual populations.

Animals↗

PubMed1977

A systems-analytical approach to macro-evolutionary phenomena.

Two sets of evolutionary phenomena find no explanation through current theory. For the static phenomena (such as homology, homonomy, systematic weight, and "Type") there is no causal base, although these principles are responsible for all phenomena of predictable order in the living world. The dynamic phenomena (such as homodynamy, coadaptation, parallel evolution, orthogenesis, Cartesian transformation, typostrophy, hetermorphosis, systemic mutation, and spontaneous atavism) have no causal explanation, although they are responsible for all directed phenomena in macroevolution. These phenomena share one unifying principle which can be explained by a system theory of evolution based on, but extending, the current synthetic theory. This system theory envisages feedback conditions between genotype and phenotype by which the chances of successful adaptation increase if the genetic units, by insertion of superimposed genes, copy the functional dependencies of those phene structures for which they code. This positive feedback of the adaptive speed (or probability) within a single adaptive direction is compensated by negative feedback in most of the alternative directions. The negative feedback operates as selection not be environmental but by systemic conditions developed by the organization of the organism. The consequences are an imitatively organized system of gene interractions, the rehabilitation of classical systematics, the reality of the "natural system," and, in general, the resolution of the contradiction between neodarwinists and their critics, between reductionists and holists, between "a priori" and "a posteriori" views, between idealism and materialism, and between the notions of freedom and of purpose in evolution.

Biological Evolution↗

PubMed1976

The genetic variability of third chromosomes in a local population of Drosophila melanogaster.

Five hundred and two third chromosomes were extracted from a large cage population of Drosophila melanogaster initiated two months after collection of the progenitors near Raleigh, North Carolina in 1970.---Salivary gland chromosomes of 489 chromosome lines were examined and 54 chromosomes were found to carry inversions. The inversions were classified into three polymorphic types [In (3L)P, In (3R)P, and In (3R)C] and two unique types. The polymorphic inversions were found in frequencies of 0.012, 0.88, and 0.010, respectively.--Viabilities of homozygotes and heterozygotes were examined. Chromosomes with lethals occurred with a frequency of 0.495: 0.537 in the group of inversion-carrying chromosomes and 0.490 in the group of inversion-free chromosomes. The average homozygote viability computed on the basis of an average heterozygote viability of 1.0000 was 0.3235 if lethal lines were included and 0.6290 if they were excluded. The detrimental load to lethal load ratio (D:L ratio) was 0.70 (=0.4636-0.6650). The average viability of lethal heterozygotes was significantly larger than that of lethal-free heterozygotes. It appears, however, that lethal genes in heterozygotes have deleterious effects on fitness as a whole.--The average degree of dominance for viability polygenes was estimated to be about 0.3-0.4 in lethal-free individuals and nearly zero in lethal heterozygotes. Overdominance or some form of balancing selection was suggested at some loci. The difference between the values obtained for average degree of dominance due to genetic backgrounds and superior vibaility of lethal heterozygotes (but not fitness as a whole) suggest that some epistasis or coadaptation occurs.--The results described above are similar to those obtained for the second chromosomes.

Animals↗

PubMed2025

The Fire Ant Social Chromosome Exerts a Major Influence on Genome Regulation.

Supergenes underlying complex trait polymorphisms ensure that sets of coadapted alleles remain genetically linked. Despite their prevalence in nature, the mechanisms of supergene effects on genome regulation are poorly understood. In the fire ant Solenopsis invicta, a supergene containing over 500 individual genes influences trait variation in multiple castes to collectively underpin a colony level social polymorphism. Here, we present results of an integrative investigation of supergene effects on gene regulation. We present analyses of ATAC-seq data to investigate variation in chromatin accessibility by supergene genotype and STARR-seq data to characterize enhancer activity by supergene haplotype. Integration with gene co-expression analyses, newly mapped intact transposable elements (TEs), and previously identified copy number variants (CNVs) collectively reveals widespread effects of the supergene on chromatin structure, gene transcription, and regulatory element activity, with a genome-wide bias for open chromatin and increased expression in the presence of the derived supergene haplotype, particularly in regions that harbor intact TEs. Integrated consideration of CNVs and regulatory element divergence suggests each evolved in concert to shape the expression of supergene encoded factors, including several transcription factors that may directly contribute to the trans-regulatory footprint of a heteromorphic social chromosome. Overall, we show how genome structure in the form of a supergene has wide-reaching effects on gene regulation and gene expression.

Animals↗

PubMed2026

Systematic identification of germ granule proteins reveals specialized roles in RNAi and small RNA inheritance.

Biomolecular condensates, such as germ granules, organize RNAi pathways critical for fertility and genome regulation. However, the protein composition and functional contributions of these condensates remain poorly defined. Here, we applied TurboID proximity labeling to the Caenorhabditis elegans germ granule protein SIMR-1, integrating mass spectrometry with genetic screening, CRISPR-based tagging, and small RNA sequencing. This systematic approach identified several previously uncharacterized germ granule proteins that contribute to fertility, germline immortality, exogenous RNAi, and transgenerational inheritance. Small RNA sequencing of 21 mutants revealed broad and class-specific defects in siRNA and miRNA biogenesis, with distinct factors associated with defects in WAGO-class 22G-RNAs, CSR-class 22G-RNAs, or histone-directed small RNAs. Among these, we identified PINT-1, a highly disordered protein that directly interacts with and is recruited to germ granules by the PIWI Argonaute PRG-1. PINT-1 is required for piRNA-dependent and -independent secondary siRNA biogenesis and germline development. Comparative genomics revealed that PINT-1 has coevolved with PRG-1 across clade V nematodes, with a conserved structured N terminus and a rapidly diverging repeat-rich intrinsically disordered region. Together, our findings expand the germ granule proteome and reveal how distinct condensate components contribute to specialized functions within the small RNA pathways, while highlighting an evolutionarily coadapted PIWI interactor critical for siRNA biogenesis.

Animals↗

PubMed2026

New Insights into Genomic Variations and Mutational Events Associated with Plant-Pathogen Interactions.

Plant diseases threaten global food security, causing up to 40% crop yield losses and more than $220 billion in annual economic damage. This review synthesizes recent advances in understanding the genomic variations and mutational events underlying plant-pathogen interactions and durable plant disease resistance. Key insights into evolutionary dynamics, genetic variability, and coadaptive strategies reveal the complexity of host-pathogen relationships and the implications for developing durable disease resistance. Integrative approaches combining genome-wide association studies and functional genomics have uncovered the polygenic and epistatic architecture of quantitative resistance. Advances in pan-genomics and high-throughput sequencing have revealed extensive genetic variability in cultivated/elite germplasm and wild relatives. Emerging technologies, including gene editing, multi-omics, and machine learning, enable predictive modeling of resistance traits and support evolution that informs plant breeding strategies. Collectively, these advances provide a robust framework for developing durable resistance and sustainable crop protection in the face of global agricultural challenges.

Host-Pathogen Interactions↗

PubMedDate not supplied

[Comparative study of cicatrization with suture technics in 1 or 2 layers in small intestine anastomosis in adverse conditions. Experimental work in dogs].

Some experimental procedures have shown in intestinal anastomosis advantages in the use of suture on only one plane as compared to the classical suture on two planes. However, these experiments, performed in healthy dogs, raised doubts about its safety when used under adverse clinical conditions. The objective of this work is, therefore, to compare in dogs submitted to immunosupressive drugs (azotioprine and corticoid) the two techniques of suture in the presence of peritonitis and intestinal ischemia. The comparative study of the healing in the sutures performed under such conditions shows the advantages in the use of suture on only one plane. In the dogs examined on the fourth and fifteenth day after surgery, the superiority of the suture on one plane compared to that on two planes is evident, both in the macroscopic and microscopic aspects. The suture in one plane shows a better coadaptation of the borders, without increasing the thickness of the wall at the level of the anastomosis, less exudative inflammatory reaction, quicker and greater fibroblastic proliferation, less inflammatory reaction to the suture material, and less vascular alteration at the healing level.

Animals↗

PubMed2026

Oxygen-responsive bacterial glycosphingolipid links symbiont fitness and immune development in neonatal host.

Symbiotic gut bacteria must re-establish themselves in every host generation, yet the molecular strategies enabling this inheritance remain poorly understood. Here, we show that Bacteroides fragilis uses a membrane glycolipid, alpha-galactosylceramide (BfaGC), to colonize the neonatal gut. Genome-wide fitness profiling revealed that BfaGC biosynthesis is selectively required during early life, when transient oxygenation creates a physiological bottleneck for strict anaerobes. Mechanistically, BfaGC reduces membrane proton permeability, sustaining the proton-motive force that supports aerobic respiration. This oxygen-responsive adaptation simultaneously generates a host-facing immunomodulatory signal that calibrates neonatal natural killer T (NKT) cell development, linking bacterial fitness to immune maturation through a single metabolite. The same mechanism also enables niche expansion by enterotoxigenic strains, revealing context-dependent consequences. Notably, this strategy is distinct among gut Bacteroidales: other prominent members synthesize a different sphingolipid subclass supporting broader fitness, implying divergent evolutionary strategies. Our findings provide time-resolved insight into how bacterial metabolites shape host-microbiota symbiosis across development.

Bacteroides fragilis↗