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PubMed2025

Experimental evolution of a pathogen confronted with innate immune memory increases variation in virulence.

Understanding the drivers and mechanisms of virulence evolution is still a major goal of evolutionary biologists and epidemiologists. Theory predicts that the way virulence evolves depends on the balance between the benefits and costs it provides to pathogen fitness. Additionally, host responses to infections, such as resistance or tolerance, play a critical role in shaping virulence evolution. But, while the evolution of pathogens has been traditionally studied under the selection pressure of host adaptive immunity, less is known about their evolution when confronted to simpler and less effective forms of immunity such as immune priming. In this study, we used a well-established insect model for immune priming - red flour beetles and their bacterial pathogen Bacillus thuringiensis tenebrionis - to test how this form of innate immune memory drives the pathogen evolution. Through controlled experimental evolution of the pathogen in primed versus non-primed hosts, we found no change in average virulence after eight selection cycles in primed host. Nonetheless, we observed a notable rise in the variability of virulence, defined as the ability to kill hosts, among independent pathogen lines that evolved in primed hosts, and the bacteria were unable to develop resistance to host priming. Whole genome sequencing revealed increased activity in the bacterial mobilome (prophages and plasmids). Expression of the Cry toxin - a well-known virulence factor - was linked to evolved differences in copy number variation of the cry-carrying plasmid, though this did not correlate directly with virulence. These findings highlight that innate immune memory can drive variability in pathogen traits, which may favor adaptation to variable environments. This underscores the need to consider pathogen evolution in response to innate immune memory when applying these mechanisms in medicine, aquaculture, pest control, and insect mass production.

Animals↗

PubMed2000

Genome evolution in polyploids.

Polyploidy is a prominent process in plants and has been significant in the evolutionary history of vertebrates and other eukaryotes. In plants, interdisciplinary approaches combining phylogenetic and molecular genetic perspectives have enhanced our awareness of the myriad genetic interactions made possible by polyploidy. Here, processes and mechanisms of gene and genome evolution in polyploids are reviewed. Genes duplicated by polyploidy may retain their original or similar function, undergo diversification in protein function or regulation, or one copy may become silenced through mutational or epigenetic means. Duplicated genes also may interact through inter-locus recombination, gene conversion, or concerted evolution. Recent experiments have illuminated important processes in polyploids that operate above the organizational level of duplicated genes. These include inter-genomic chromosomal exchanges, saltational, non-Mendelian genomic evolution in nascent polyploids, inter-genomic invasion, and cytonuclear stabilization. Notwithstanding many recent insights, much remains to be learned about many aspects of polyploid evolution, including: the role of transposable elements in structural and regulatory gene evolution; processes and significance of epigenetic silencing; underlying controls of chromosome pairing; mechanisms and functional significance of rapid genome changes; cytonuclear accommodation; and coordination of regulatory factors contributed by two, sometimes divergent progenitor genomes. Continued application of molecular genetic approaches to questions of polyploid genome evolution holds promise for producing lasting insight into processes by which novel genotypes are generated and ultimately into how polyploidy facilitates evolution and adaptation.

Evolution, Molecular↗

PubMed1998

A combined evolution method for associative memory networks.

In the study of associative memory networks, the updating rule remains unchanged during neuron evolution. When evolution stops at an undesired minimum, simulated annealing is used to resolve the problem. In this paper, a combined neuron evolution method based on a multipath network architecture is presented. It is shown that, by controlling the evolution path, the probability that evolution terminates in undesired, minima is significantly reduced. Once evolution is trapped in an undesired minimum with respect to one path, the method seeks an alternative path to carry on the evolution. The process continues until a desired minimum is reached. Visual examples are used to demonstrate the performance of the method.

Journal Article↗

PubMed1996

Molecular phylogeny analysis of fiddler crabs: test of the hypothesis of increasing behavioral complexity in evolution.

The current phylogenetic hypothesis for the evolution and biogeography of fiddler crabs relies on the assumption that complex behavioral traits are assumed to also be evolutionary derived. Indo-west Pacific fiddler crabs have simpler reproductive social behavior and are more marine and were thought to be ancestral to the more behaviorally complex and more terrestrial American species. It was also hypothesized that the evolution of more complex social and reproductive behavior was associated with the colonization of the higher intertidal zones. Our phylogenetic analysis, based upon a set of independent molecular characters, however, demonstrates how widely entrenched ideas about evolution and biogeography led to a reasonable, but apparently incorrect, conclusion about the evolutionary trends within this pantropical group of crustaceans. Species bearing the set of "derived traits" are phylogenetically ancestral, suggesting an alternative evolutionary scenario: the evolution of reproductive behavioral complexity in fiddler crabs may have arisen multiple times during their evolution. The evolution of behavioral complexity may have arisen by coopting of a series of other adaptations for high intertidal living and antipredator escape. A calibration of rates of molecular evolution from populations on either side of the Isthmus of Panama suggest a sequence divergence rate for 16S rRNA of 0.9% per million years. The divergence between the ancestral clade and derived forms is estimated to be approximately 22 million years ago, whereas the divergence between the American and Indo-west Pacific is estimated to be approximately 17 million years ago.

Journal Article↗

PubMed1998

Ethylene evolution, radial growth and carbohydrate concentrations in Abies balsamea shoots ringed with Ethrel.

The terminal (1-year-old) shoot of quiescent, 2-year-old Abies balsamea (L.) Mill. seedlings was either left untreated or ringed with 0, 1 or 10 mg Ethrel g(-1) lanolin. After 5 weeks of culture under environmental conditions favorable for growth, the shoots were harvested to measure ethylene evolution and carbohydrate concentrations by gas chromatography, and tracheid number and bark radial width by microscopy. In untreated shoots, the basal rate of ethylene evolution followed the order: cambial region > cortex + periderm = xylem + pith = needles. Wound-induced ethylene production was not detected until at least 4 h after excision, but was evident in all fractions 24 h after excision; the increase in wound-induced ethylene evolution followed the order: cambial region > cortex + periderm > xylem + pith > needles. Compared with untreated controls, the application of plain lanolin, which involved the removal of needles and periderm, increased bark radial width and wound-induced ethylene production by the cambial region and the cortex + periderm, but decreased cambial region concentrations of fructose, glucose and starch at the application point. At the application point, Ethrel concomitantly increased ethylene evolution from the cambial region and the cortex + periderm, tracheid number, bark radial width, and the cambial region concentrations of fructose, glucose, sucrose and starch. No effects of Ethrel treatment were detected above or below the application point, with the exception that the 10 mg g(-1) Ethrel treatment stimulated ethylene evolution and decreased starch concentration of the cambial region. The results indicate that: (1) the cambial region is the major source of endogenous ethylene in the 1-year-old shoot; (2) the magnitude of the difference in ethylene evolution between particular shoot fractions is different before and after the start of wound-induced ethylene production; (3) the Ethrel-induced increase in tracheid number and bark radial width at the application point is positively related to ethylene evolution from the cambial region and the cortex + periderm, respectively; and (4) ethylene derived from Ethrel applied laterally to a woody stem can mobilize carbohydrates to the application point.

Journal Article↗

PubMed1985

The myelodysplastic syndromes: different evolution patterns based on sequential morphological and cytogenetic investigations.

Serial morphological and cytogenetic investigations were performed in 46 patients with the myelodysplastic syndrome (MDS). Twenty-one patients (45.5%) progressed to AML (greater than 30% blasts in bone marrow smears). Based on sequential determinations of percentages of bone marrow blasts, three patterns of evolution were observed in MDS. Patients with evolution pattern A (48%) had an apparently stable disease with minimal or no increase in bone marrow blasts. Exceptionally they developed new or additional chromosomal anomalies during the course of their disease. Cases in this group, who showed no abnormal localization of immature myeloid precursors (ALIP) at time of diagnosis experienced prolonged survival (median: 43 months), while ALIP positive patients had shorter survival times (median: 14 months), with high probability of early death from infections and/or bleeding problems. Patients with evolution pattern B (28%) initially had a morphologically stable disease, comparable to cases with evolution pattern A, but showed an abrupt shift from MDS to AML. Most of these patients (82%) were ALIP positive and a substantial proportion (46%) showed karyotype anomalies at diagnosis. The abrupt shift to AML in these patients was frequently (61.5%) associated with additional cytogenetic anomalies. Patients with evolution pattern C (24%) showed a gradual increase in bone marrow blasts. The majority of these cases (8/11) ultimately developed acute myeloid leukaemia (gradual progression to AML), whereas some patients (3/11) died from infections and/or haemorrhagic complications before they had reached the level of clinical AML. All of these patients were ALIP positive at diagnosis and no additional cytogenetic alterations occurred during evolution. Acquisition of new karyotypic anomalies during the course of MDS was almost invariably associated with abrupt shift to AML. From this retrospective study we conclude that evolution in MDS shows two important aspects, which seem to be preponderant in determining the course and outcome of the disease: one is the proliferative capacity and resulting growth advantage of the neoplastic clone over normal haematopoiesis, as measured by increasing percentages of bone marrow blasts in sequential aspirates; the other one is instability of the clone. Unstable clones have a high propensity to further intraclonal changes; they are expressed morphologically by the abrupt increase in bone marrow blasts and cytogenetically by the acquisition of new or additional karyotype anomalies.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed2002

The impact of clonal evolution on response to imatinib mesylate (STI571) in accelerated phase CML.

In chronic myelogenous leukemia (CML), the development of chromosomal abnormalities in addition to the Philadelphia chromosome (clonal evolution) is considered by many to be a feature of accelerated phase (AP). Imatinib mesylate (STI571), a selective inhibitor of the Bcr-Abl tyrosine kinase, has significant activity in AP CML. As clonal evolution could allow Bcr-Abl independent proliferation, we analyzed its impact on the outcome of 71 AP patients treated with 600 mg of imatinib mesylate. Fifteen patients had clonal evolution alone (AP-CE), 32 had AP features but no evidence of clonal evolution (HEM-AP), and 24 had AP features plus clonal evolution (HEM-AP + CE). Of the AP-CE patients, 73% had a major cytogenetic response, compared with 31% of the HEM-AP patients (P =.043) and 12.5% of the HEM-AP + CE patients (P =.007). Complete cytogenetic responses were seen in 60% of AP-CE patients, compared with 31% of HEM-AP patients (P =.19) and 8% of HEM-AP + CE patients (P <.001). With mean follow-up of 11.2 months, 35% of all patients failed treatment. The lowest estimated rate of treatment failure at 1 year, 0%, was seen in AP-CE patients, compared with rates of 31% for HEM-AP patients and 69% for HEM-AP + CE patients (P =.0004). After 1 year, 100% of AP-CE patients were still alive, compared with 85% of HEM-AP patients and 67.5% of HEM-AP + CE patients (P =.01). In conclusion, in patients with clonal evolution as the sole criterion of disease acceleration, good responses to imatinib are still possible. Once patients have other signs of acceleration, clonal evolution predicts lower response rates and a shorter time to treatment failure.

Adult↗

PubMed1996

Significance of cytogenetic clonal evolution in chronic myelogenous leukemia.

PURPOSE: To describe the incidence and significance of clonal evolution patterns. PATIENTS AND METHODS: We analyzed 264 patients with Philadelphia chromosome (Ph)-positive chronic myelogenous leukemia (CML) who developed clonal evolution between 1967 and 1993. RESULTS: The median survival time following clonal evolution was 19 months. Factors associated with worse survival (P < .01) were as follows: chromosome 17 abnormality or chromosomal translocations other than Ph, high percentage of abnormal metaphases, longer time to clonal evolution, and presence of other accelerated-phase features. A recursive partitioning technique (CART) identified different risk groups. The best group (37 patients; no chromosome 17 abnormality, abnormal metaphases < 16%, and interval to clonal evolution < or = 24 months) had an estimated median survival time of 54 months. The worst two groups included 27 patients with chromosome 17 abnormalities and > or = 36% abnormal metaphases (estimated median survival time, 6 months), and 22 patients with other accelerated features and > or = 16% abnormal metaphases (estimated median survival time, 7 months). The intermediate group had an estimated median survival time that ranged from 13 to 24 months. Prior interferon therapy evaluated within risk groups showed a significant survival advantage only in the intermediate-risk group. A multivariate analysis showed similar results, and identified the following independent poor prognostic variables: chromosome 17 abnormality, percentage of abnormal metaphases (cutoff, 24%), longer time to clonal evolution (cutoff, 24 months), other accelerated-phase features, and no prior interferon therapy. Patients with none, one, two, three, or more of the first four features had median survivals times of 51, 24, 14, and 7 months, respectively. CONCLUSION: The prognostic significance of clonal evolution in CML is not uniform and is related to the specific abnormality, time to its development, its predominance in metaphases, and the presence of other accelerated features, and it may be modified by specific therapies.

Bone Marrow Transplantation↗

PubMed1976

Effect of hydrogen ion buffers on photosynthetic oxygen evolution in the blue-green alga, Agmenellum quadruplicatum.

The photosynthetic oxygen evolution capacity of Agmenelium quadruplication suspended in four hydrogen ion buffers (pH 7.4, 0.05 M) and its synthetic marine growth medium was measured with an oxygen electrode. High rates of oxygen evolution were obtained in the growth medium and N-tris(hydroxymethyl)-methylglycine (Tricine) buffer. Compared to oxygen evolution in the growth medium, rates in phosphate buffer and N-tris(hydroxymethyl)-2-aminoethanesulphonic acid (TES) buffer were sometimes reduced by up to 30% and rates in tris (hydroxymethyl) amino-methane (Tris) were consistently reduced by 50%. An incubation-rinsing procedure caused inhibition of oxygen evolution in TES, phosphate, and Tris by 50 to 100%. Oxygen evolution could be restored to cells rinsed in TES or phosphate by resuspension in growth medium or in buffer plus magnesium and calcium ions. Bezoquinone-supported oxygen evolution was not affected by rinsing with any buffer tested except Tris. Ferricyanide was photoreduced at a low rate by cells rinsed in Tes but at a high rate in TES plus magnesium and calcium ions. We interpreted our results to mean that, in Agmenellum quadruplicatum, inhibition of photosynthetic oxygen evolution by Tris occurs at the level of photosystem 2 while the effects of TES and phosphate are on electron-transport occurring after the rate-limiting reaction.

Buffers↗

PubMedDate not supplied

Correlation between respiratory function tests and evolution time in asthmatic patients.

A transversal and prospective study was performed to demonstrate a relationship between the evolution time of asthma episodes and alterations observed in the respiratory function tests (RFT) during asymptomatic periods. Asthmatic patients (n = 80) of both sexes, were studied, we investigated the evolution time of the asthmatic episodes and performed RFTs in the patients during their asymptomatic periods. Respiratory patterns were classified as normal, obstructive, or mixed (obstructive-restrictive), and a Spearman correlation test was performed. Twenty nine patients were male and fifty one female. All were between 5 and 49 years of age. Of the total number of patients, 13.7% fell into a normal pattern, 57.5% into an obstructive pattern and 28.7% in a mixed pattern. In the groups showing the shortest evolution time, the obstructive pattern was more common (75% of patients with less than 5 years of evolution time and 53.8% with an evolution time between five and ten years). The mixed pattern was more common in patients with more years suffering asthma (16.6% in the group of patients having 5 or less years of evolution and 50% in the group with more than 20 years). We found a Spearman value of 0.7, and we can conclude that there is more pulmonary damage associated to a longer evolution period of bronchial asthma.

Adolescent↗

PubMed1993

[Changes in the pancreatic and respiratory functions in cystic fibrosis. The influence of the time of the evolution of the disease].

BACKGROUND: Cystic fibrosis is the most frequent congenital disease in Caucasian and is transmitted by recessive autosomic inheritance. It is characterized by affection of different glands of exocrine secretion, particularly the pancreas and the lung. The aim of this study was to analyze the degree of alteration of pulmonary and pancreatic exocrine function in a group of patients with cystic fibrosis in relation to the time of disease evolution. METHODS: Twenty-one patients between 9 and 31 years of age were studied; 11 with an evolution of lower than or equal to 158 months and 10 with an evolution of higher than 158 months (median of the total patients). To study pancreatic exocrine function the BT-PABA test immunoreactive serum trypsin test were used. To evaluate respiratory function FEV1, FVC, FEV1/FVC ratio and PaO2 were used. RESULTS: The results obtained demonstrated that in the group with a lower time of evolution the diagnosis had been carried out at earlier ages (17 +/- 17 months versus 84 +/- 60 months; p = 0.002) and presented a significantly more altered pancreatic exocrine function (BT-PABA: 13 +/- 12% versus 35 +/- 23%; p = 0.013). However, respiratory function was altered in the group with longer time of evolution (FEV1: 68 +/- 20% versus 36 +/- 23%; p = 0.003; FVC: 74 +/- 9 versus 52 +/- 25%; p = 0.013; FEV1/FEV: 77 +/- 19 versus 50 +/- 9%; p < 0.001; PaO2: 84 +/- 16 versus 58 +/- 11%; p < 0.001). CONCLUSIONS: Pancreatic exocrine function is most intensely affected in patients diagnosed with cystic fibrosis at earlier and with shorter times of evolution while patients who have the longest time of evolution and who were diagnosed later in life presented greater changes in respiratory function.

Adolescent↗

PubMed1998

[Prostate cancer in Isère and Tarn (France) between 1985 and 1995: evolution of therapeutic indications].

The objective is to describe the evolution of therapeutic practices of prostate carcinoma in the departements of Tarn and Isère in France for the 1985-1995 period. This retrospective study is based on patient folders for whom a prostate carcinoma has been diagnosed between 1985 and 1995. A sample of 871 patients have been included after randomisation stratified on the year and the department of the diagnostic in the files of the cancer registries of Tarn and Isère. Therapeutic practices of the prostate cancer have significantly evolved between 1985 and 1989. The rate of radical prostatectomies increased from 1986 whereas the rate of radiotherapy remained stable. This evolution has been made to the detriment of non curative treatments with the decrease of the rate of hormonotherapies. This is due to the important development of diagnostic technics which led to an earlier diagnostic of these cancers; but, the evolution of therapeutic technics and particularly of the radical prostatectomy allowed the evolution of indications for the treatment of this cancer, with the increase of the rate of radical prostatectomies and the decrease of the rate of radiotherapies at the same stage of disease evolution. For 1990 to 1995, there was no major evolution. Some indications are discussed in this disease touching old man, with a slow evolution.

Adenocarcinoma↗

PubMed2025

Phylogenomics Unveils the Complex Evolution of Retroviruses in Birds.

The rise of birds represents one of the major evolutionary transitions in the history of life. Yet, much remains obscure about the origins and diversification of viruses in birds. Endogenous retroviruses (ERVs), relics of past retroviral infections, provide molecular fossils for interrogating the evolution and ecology of retroviruses. Here, we perform phylogenomic mining of ERVs within the genomes of 758 bird species and identify more than 470,000 ERVs, revealing a highly diverse and complex retrovirus repertoire in birds. These ERVs greatly expand the diversity of retroviruses in birds, indicating that exogenous retroviruses characterized in birds to date are highly underestimated. The evolution of retroviruses in birds is shaped by both coevolution and cross-species transmission. Tens of retrovirus lineages originated during the early evolution of birds, four of which contribute to more than 90% of complete ERVs in birds. We also observe recent ERV activity across the bird phylogeny (particularly in Passeriformes). Moreover, we find that ERVs can mediate genome rearrangements, potentially facilitating the genome evolution of birds. Many bird retroviruses recruited genes of cellular provenience, which might drive the evolution of the genome complexity of retroviruses. Together, these results unveil a diverse and complex retrovirosphere in birds and provide insights into the intricate evolution of retrovirus-bird interaction.

Animals↗

PubMed2002

Diversifying selection of the tumor-growth promoter angiogenin in primate evolution.

Diversifying selection drives the rapid differentiation of gene sequences and is one of the main forces behind adaptive evolution. Most genes known to be shaped by diversifying selection are those involved in host-pathogen or male-female interactions characterized as molecular "arms races." Here we report the unexpected detection of diversifying selection in the evolution of a tumor-growth promoter, angiogenin (ANG). A comparison among 11 primate species demonstrates that ANG has a significantly higher rate of nucleotide substitution at nonsynonymous sites than at synonymous sites, a hallmark of positive selection acting at the molecular level. Furthermore, we observed significant charge diversity at the molecular surface, suggesting the presence of selective pressures in the microenvironment of ANG, including its binding molecules. A population survey of ANG in chimpanzees, however, reveals no polymorphism, which may have resulted from a recent selective sweep of a charge-altering substitution in chimpanzee evolution. Functional assays of recombinant ANGs from the human and owl monkey indicate that primate ANGs retain angiogenic activity despite rapid evolution. Our study, together with findings of similar selection in the primate breast cancer suppressor gene, BRCA1, reveals an intriguing phenomenon of unusual selective pressures on, and adaptive evolution of, cancer-related genes in primate evolution.

Amino Acid Sequence↗

PubMed2000

Evolution of vertebrate immunoglobulin variable gene segments.

Evolution of Ig V gene segments are generally characterized by (a) evolution by "the birth and death process" and (b) diversifying selection. However, the detailed evolutionary pattern of V gene segments varies among species due to the fact that the humoral immune system itself has changed during vertebrate evolution. The change in somatic diversification system coupled with the change in lymphocyte development has imposed a significant impact on the evolution of Ig genes. In order to understand the evolution of immunological genes it is important to view it in the context of the evolution of the entire immune system itself.

Animals↗

PubMed1993

Characterization of the cow stomach lysozyme genes: repetitive DNA and concerted evolution.

Cow stomach lysozyme genes have evolved in a mosaic pattern. The majority of the intronic and flanking sequences show an amount of sequence difference consistent with divergent evolution since duplication of the genes 40-50 million years ago. In contrast, exons 1, 2, and 4 and immediately adjacent intronic sequences differ little between genes and show evidence of recent concerted evolution. Exon 3 appears to be evolving divergently. The three characterized genes vary from 5.6 to 7.9 kilobases in length. Different distributions of repetitive DNA are found in each gene, which accounts for the majority of length differences between genes. The different distributions of repetitive DNA in each gene suggest the repetitive elements were inserted into each gene after the duplications that give rise to these three genes and provide additional support for divergent evolution for the majority of each gene. The observation that intronic and flanking sequences are evolving divergently suggests that the concerted evolution events involved in homogenizing the coding regions of lysozyme genes involve only one exon at a time. This model of concerted evolution would allow the shuffling of exon-sized pieces of information between genes, a phenomenon that may have aided in the early adaptive evolution of stomach lysozyme.

Animals↗

PubMed1993

The D/H ratio and the evolution of water in the terrestrial planets.

The presence of liquid water at the surface of the Earth has played a major role in the biological evolution of the Earth. None of the other terrestrial planets--Mercury, Venus and Mars--has liquid water at its surface. However, it has been suggested, since the early seventies, from both geological and atmospheric arguments that, although Venus and Mars are presently devoid of liquid water, their surfaces could have been partially or completely covered by water at some time of their evolution. There are many possible diagnostics of the long-term evolution of the planets, either from the present characteristics of their surfaces or from their present atmospheric compositions. Among them, the present value of the D/H ratio is of particular interest, although its significance in terms of long term evolution has been challenged by some authors. Recent progress has been made in this field. We now have evidence for higher D/H ratios on Mars and Venus than on Earth, with an enrichment factor of the order of 5 on Mars, and about 100 on Venus. Any scenario for the evolution of these planets must take this into The most recent models on the evolution of Mars and Venus are reviewed in light of these new measurements.

Atmosphere↗

PubMed1981

Simulation of protein evolution by random fixation of allowed codons.

Computer simulation of protein evolution is based on a simple model consisting of random fixation of allowed codons (RFAC). Random replacement of single nucleotides occurs in a DNA sequence. If this results in any of the synonomous codons for allowed amino acids the mutation is fixed, if not, there is no change in the DNA and the cycle is repeated. Multiple fixations at the same nucleotide site, back mutations, degenerate fixations and coincidental identity of amino acids all occur. RFAC simulation begins with a single DNA sequence and follows a phylogeny based on the fossil record. The rate of fixation at the level of DNA is constant. The model upon which RFAC simulation is based is the same as the neutral theory of molecular evolution. The simulation is therefore a test of this theory. The results of simulated and real evolution are compared for fibrinopeptides A in mammals and cytochromes C and hemoglobin alpha and beta chains in vertebrates. In each case the allowed variation at each site has been set equal to that observed, twice that observed and all protein amino acids. Rates of fixation vary from 2.4 X 10(-10) to 10(-8) accepted nucleotide fixations per codon per year. There is some, although never excellent, agreement between real and simulated evolution, the better fits are obtained in the cases of fibrinopeptides A and cytochromes C. The major source of discrepancy between real evolution and simulation is irregularities in the rates of real evolution. RFAC simulation is compared with the random evolutionary hit (REH) model, augmented maximum parsimony and the accepted point mutations (PAM) approach.

Amino Acids↗