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Results for “Comparative evolution”

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PubMed1986

Comparative morphology and evolution of cheek pouches in rodents.

There are two types of cheek pouches in extant rodents. Internal cheek pouches are evaginations of the oral cavity deep to M. platysma and M. sphincter colli profundus, and have evolved independently in some species of the superfamilies Sciuroidea and Muroidea. External, furlined cheek pouches open lateral to and separate from the oral cavity, (also deep to M. platysma and M. sphincter colli profundus), and occur in all species of the families Geomyidae and Heteromyidae. The presence of external, furlined cheek pouches is a synapomorphy for the superfamily Geomyoidea. The posterior retractor muscle of the pouch is derived from facial musculature in sciurids, from trapezius musculature in cricetids, and from both facial and trapezius muscle groups in the Geomyoidea. Differences also exist in the musculature associated with the pouch opening. In the Sciuridae and Cricetidae, the M. buccinatorius muscle group acts as a sphincter to control the size of the pouch opening. In the Geomyoidea, the size of the opening is controlled by the M. orbicularis sacculi in concert with a slip of the M. platysma myoides. Thin sections and scanning electron micrographs of the pouch tissue reveal the presence of dermal papillae in Phodopus sungorus but not in a close relative, Mesocricetus auratus. All members of the subfamily Cricetinae have a peninsula of highly folded tissue projecting anteriorly from the posteromedial pouch wall. This folding allows for expansion of the pouch walls when food is stored in the pouch.

Animals↗
PubMedDate not supplied

Experimental evaluation of rigor mortis. III. Comparative study of the evolution of rigor mortis in different sized muscle groups in rats.

The use of new methods and an appropriate apparatus has allowed us to make successive measurements of rigor mortis and a study of its evolution in the rat. By a comparative examination on the front and hind limbs, we have determined the following: (1) The muscular mass of the hind limbs is 2.89 times greater than that of the front limbs. (2) In the initial phase rigor mortis is more pronounced in the front limbs. (3) The front and hind limbs reach maximum rigor mortis at the same time and this state is maintained for 2 hours. (4) Resolution of rigor mortis is accelerated in the front limbs during the initial phase, but both front and hind limbs reach complete resolution at the same time.

Animals↗
PubMed2026

Comparative Genomics Reveals Convergent Evolution Between Avivorous Bats (Ia io and Nyctalus aviator).

Investigating the genetic basis of dietary specialization can provide insights into the evolution of niche breadth. In this study, we employed comparative genomics to investigate the adaptive mechanisms enabling two bat species (Nyctalus aviator and Ia io) to shift from insectivory to seasonal bird consumption (avivorous bats). Our findings revealed adaptation related to immune response and lipid metabolism in avivorous bat species. Avivorous bats exhibit strong positive selection and convergent evolution in immune-related genes, which are under heightened selective pressure compared to those of non-avivorous bats. These species also display significantly fewer endogenous retroviral elements. These findings emphasized the significance of immune-driven adaptive evolution in avivory. Additionally, our results showed that the dietary evolution of avivorous bats is accompanied by convergent evolution associated with the lipid metabolism. Notably, CEPT1, the upstream gene required for the activation of the PPAR pathway, underwent positive selection and convergence, which may have affected lipid metabolism. These adaptations may enable avivorous bat species to face the challenge of immune response and nutrition during dietary niche expansion. These findings not only provide comprehensive insights into the adaptive evolution driving the unique diet of avivorous bats but also offered novel perspectives on the molecular mechanisms underlying ecological niche evolution in a dietary context.

Animals↗
PubMed1977

Takeover mechanisms and early biochemical evolution.

It is common feature of comparatively recent evolution that a structure adapted to one function turns out also to have another function, or another way of performing an existing one. It is proposed that while our central biochemical machinery was actively evolving there were such discoveries and takeovers that provided routes to radically new disigns. The recognition and control techniques of protein would seem to be replacements for earlier approaches to similar functions. Polynucleotides may have been more widely used here in a pre-protein era. But even nucleic acid is seen as the outcome of a takeover, from an earlier quite different genetic material with properties more appropriate to primitive conditions and to primitive techniques of molecular control.

Biological Evolution↗
PubMed2024

Repeated evolution on oceanic islands: comparative genomics reveals species-specific processes in birds.

Understanding the interplay between genetic drift, natural selection, gene flow, and demographic history in driving phenotypic and genomic differentiation of insular populations can help us gain insight into the speciation process. Comparing patterns across different insular taxa subjected to similar selective pressures upon colonizing oceanic islands provides the opportunity to study repeated evolution and identify shared patterns in their genomic landscapes of differentiation. We selected four species of passerine birds (Common Chaffinch Fringilla coelebs/canariensis, Red-billed Chough Pyrrhocorax pyrrhocorax, House Finch  Haemorhous mexicanus and Dark-eyed/island Junco Junco hyemalis/insularis) that have both mainland and insular populations. Changes in body size between island and mainland populations were consistent with the island rule. For each species, we sequenced whole genomes from mainland and insular individuals to infer their demographic history, characterize their genomic differentiation, and identify the factors shaping them. We estimated the relative (Fst) and absolute (dxy) differentiation, nucleotide diversity (π), Tajima's D, gene density and recombination rate. We also searched for selective sweeps and chromosomal inversions along the genome. All species shared a marked reduction in effective population size (Ne) upon island colonization. We found diverse patterns of differentiated genomic regions relative to the genome average in all four species, suggesting the role of selection in island-mainland differentiation, yet the lack of congruence in the location of these regions indicates that each species evolved differently in insular environments. Our results suggest that the genomic mechanisms involved in the divergence upon island colonization-such as chromosomal inversions, and historical factors like recurrent selection-differ in each species, despite the highly conserved structure of avian genomes and the similar selective factors involved. These differences are likely influenced by factors such as genetic drift, the polygenic nature of fitness traits and the action of case-specific selective pressures.

Animals↗
PubMed1982

Antigenic conservation of brain guanylate cyclase during evolution.

A comparative study of brain guanylate cyclase from different animal species (including man, bird, fish and amphibian) has been performed using a specific antibody directed against soluble rat brain guanylate cyclase. Analyses were performed on supernatant fractions by the double-immunodiffusion test, by the protein blotting technique after SDS-polyacrylamide gel electrophoresis and by analytical isoelectric focusing on agarose allowing specific immunodetection of isoelectric patterns. Membrane-bound guanylate cyclase from rat brain and soluble guanylate cyclase from several rat tissues cross-reacted with the antibody. All the brain enzymes tested were found to be identical by double-immunodiffusion. The electrophoretic and isoelectrophoretic profiles of the different brain guanylate cyclases were found to exhibit many common features with some differences between mammalian and non-mammalian enzymes. In human brain, guanylate cyclase has been localized in glial and neuronal cells by immunohistochemistry. The results demonstrate that guanylate cyclase has been well conserved during the course of evolution and are consistent with the involvement of guanylate cyclase and cyclic GMP in basic cellular function.

Animals↗
PubMed1990

Traumatic aphasia in children and adults: a comparison of clinical features and evolution.

We compared the performance on test of language, apraxia, acalculia and intelligence of 32 children--age 5 to 16 years--and 31 adults, seen at our Aphasia Unit for the sequelae of a brain trauma. Logorrhea was never present among children who had nonfluent aphasia more frequently than adults. Apraxia and acalculia were equally present in the two groups. Twelve children and 15 adults of the first study were retested at variable distance from trauma. No group difference was found in the recovery of auditory comprehension (Token Test) or oral expression (oral confrontation naming and telling-of-an-event). On a battery of verbal and spatial memory tests 6 of the 12 children had pathological scores in one or more tests. Scholastic achievements were compared with those of the nearest kin. We conclude that while aphasia profiles are different in children and adults, the incidence of apraxia and acalculia and the recovery rate do not discriminate the two groups.

Achievement↗
PubMed1976

Comparative study of plasma cortisol evolution in TRH or placebo injected patients with or without thyroid disease.

The plasma cortisol evolution under TRH has been compared in 27 euthyroid, 12 hyperthyroid and 5 patients with hot nodules and in 15 control individuals receiving a placebo or sham injection. The results showed no statistical difference in plasma cortisol evolution between the groups, suggesting no influence of the thyroid status or TSH secretion on the spontaneous fall of cortisol level during the time of the test.

Clinical Trials as Topic↗
PubMed2026

Experimental evolution reveals contrasting adaptive landscapes in lab and field environments.

Experimental evolution is widely used to infer microbial responses to environmental change, yet most laboratory studies impose constant, well-mixed conditions that differ fundamentally from fluctuating, spatially structured field environments. We compared genomic evolution in the leaf litter-associated bacterium Curtobacterium strain MMLR14_002 under control and warming treatments in laboratory culture and in a complementary field experiment. Laboratory-derived isolates accumulated more mutations per genome and exhibited stronger locus-level parallelism, with mutations recurring in a small number of coding loci. Field-derived isolates accumulated fewer mutations per genome, and these mutations rarely occurred in the same coding loci across replicate populations. Instead, field isolates exhibited a higher proportion of intergenic mutations, with mutations recurring in the same intergenic regions across independent field deployments. When coding mutations were detected in the field, they were distributed across functionally diffuse targets and more often involved metabolic pathways than the core cellular processes repeatedly targeted during laboratory evolution. Warming itself did not consistently influence mutation accumulation or the genomic distribution of mutations; instead, laboratory and field contexts primarily shaped the accumulation, targets, and repeatability of genomic change. These results suggest that laboratory thermal evolution identifies adaptive routes favored under sustained selection but may overestimate coding-level parallelism under heterogeneous field conditions. Bridging laboratory and field evolution will likely require experimental designs that incorporate temporal variability and spatial heterogeneity characteristic of natural systems.IMPORTANCEA central goal of experimental evolution is to infer how microbes evolve in nature from laboratory studies. Here, we evaluate this assumption by comparing genomic evolution of a leaf litter-associated Curtobacterium strain in laboratory and field warming experiments to identify broad patterns rather than isolate the contribution of any single environmental factor. We find that the strong parallelism at coding loci observed under laboratory conditions is reduced in the field, while mutations recurring in the same intergenic regions across field deployments suggest that parallel evolution in nature may more often involve regulatory noncoding regions rather than coding targets. These results show that environmental context reshapes adaptive landscapes and may limit the parallelism of coding-level genomic responses inferred from homogeneous laboratory conditions.

experimental evolution↗
PubMed1992

Rates of mitochondrial DNA evolution in sharks are slow compared with mammals.

The rate of mitochondrial DNA (mtDNA) evolution has been carefully calibrated only in primates. Similarity between the primate calibration and rates estimated for other vertebrates has led to widespread assumption of a constant molecular clock in vertebrates even though this has never been rigorously tested. We report here the examination of mtDNA sequence variation for 13 species of sharks from two orders that are well represented in the fossil record to test the constancy hypothesis. Nucleotide substitution rates in the cytochrome b and cytochrome oxidase I genes in sharks are seven- to eightfold slower than in primates or ungulates. This difference in substitution rate cannot be explained by nucleotide composition bias, codon-usage bias, selection, or choice of genes sequenced, and was confirmed by comparing species recently separated by the rise of the Isthmus of Panama. Such differences in mtDNA substitution rates among taxa indicate that it is inappropriate to use a calibration for one group to estimate divergence times or demographic parameters for another group. High-resolution studies of molecular evolutionary rates require taxon-specific calibrations.

Animals↗
PubMed1992

Purification and characterization of a 65-kDa tumor-associated phosphoprotein from rat transplantable hepatocellular carcinoma 1682C cell line.

We have isolated a homogeneous tumor-associated phosphoglycoprotein of about 65 kDa (p65) by ammonium sulfate precipitation of proteins from conditioned medium containing the rat transplantable hepatocellular carcinoma 1682C cell line, followed by high-performance liquid chromatography on molecular-sieving and phenyl hydrophobic interaction columns. The protein was concentrated in a Rotofor isoelectric focusing cell and finally separated by isoelectrofocusing followed by SDS--polyacrylamide gel electrophoresis. We achieved a purification of approximately 11,000-fold after the Rotofor concentration step. This protein migrated as a single band upon electrophoresis in SDS-PAGE and had a pI of 5.8 in isoelectrofocusing gels. The carbohydrate content of the blotted phosphoglycoprotein was analyzed by probing the blots with biotinylated lectins; a positive reaction was detected with concanavalin A, wheat-germ agglutinine, and Ricinus communis agglutinine. To confirm the tumor origin of this molecule, hepatocellular carcinoma cells were labeled in vivo using [32P]orthophosphate as well as [35S]methionine and cell culture medium was analyzed for the presence of radioactive band that corresponds with our protein. Phosphoamine acid analysis by thin-layer chromatography showed the presence of phosphotyrosine, phosphothreonine, and phosphoserine, which was later confirmed by analysis of the amino acid composition. Using the method described by Marchalonis and Weltman for comparative analysis of protein structure and evolution, we compared the protein isolated by us with other tumor markers and proteins showing similar properties and found no significant similarities.

Animals↗