RESUMO
Outgroup selection has been a major challenge since the rise of phylogenetics, and it has remained so in the phylogenomic era. Our goal here is to use large phylogenomic animal datasets to examine the impact of outgroup selection on the final topology. The results of our analyses further solidify the fact that distant outgroups can cause random rooting, and that this holds for concatenated and coalescent-based methods. The results also indicate that the standard practice of using multiple outgroups often causes random rooting. Most researchers go out of their way to get multiple outgroups, as this has been standard practice for decades. Based on our findings, this practice should stop. Instead, our results suggest that a single (most closely) related relative should be selected as the outgroup, unless all outgroups are roughly equally closely related to the ingroup.
Assuntos
Filogenia , AnimaisRESUMO
Collectively, we have been reviewers for microbial ecology, genetics and genomics studies that include environmental DNA (eDNA), microbiome studies, and whole bacterial genome biology for Microbial Ecology and other journals for about three decades. Here, we wish to point out trends and point to areas of study that readers, especially those moving into the next generation of microbial ecology research, might learn and consider. In this communication, we are not saying the work currently being accomplished in microbial ecology and restoration biology is inadequate. What we are saying is that a significant milestone in microbial ecology has been reached, and approaches that may have been overlooked or were unable to be completed before should be reconsidered in moving forward into a new more ecological era where restoration of the ecological trajectory of systems has become critical. It is our hope that this introduction, along with the papers that make up this special issue, will address the sense of immediacy and focus needed to move into the next generation of microbial ecology study.
Assuntos
Ecologia , Microbiota , Genômica , Genoma BacterianoRESUMO
The placozoan Trichoplax adhaerens is a tiny hairy plate and more simply organized than any other living metazoan. After its original description by F.E. Schulze in 1883, it attracted attention as a potential model for the ancestral state of metazoan organization, the "Urmetazoon". Trichoplax lacks any kind of symmetry, organs, nerve cells, muscle cells, basal lamina, and extracellular matrix. Furthermore, the placozoan genome is the smallest (not secondarily reduced) genome of all metazoan genomes. It harbors a remarkably rich diversity of genes and has been considered the best living surrogate for a metazoan ancestor genome. The phylum Placozoa presently harbors three formally described species, while several dozen "cryptic" species are yet awaiting their description. The phylogenetic position of placozoans has recently become a contested arena for modern phylogenetic analyses and view-driven claims. Trichoplax offers unique prospects for understanding the minimal requirements of metazoan animal organization and their corresponding malfunctions.
Assuntos
Placozoa , Animais , Evolução Biológica , Genoma , Filogenia , Placozoa/genéticaRESUMO
The placozoan Trichoplax adhaerens has been bridging gaps between research disciplines like no other animal. As outlined in part 1, placozoans have been subject of hot evolutionary debates and placozoans have challenged some fundamental evolutionary concepts. Here in part 2 we discuss the exceptional genetics of the phylum Placozoa and point out some challenging model system applications for the best known species, Trichoplax adhaerens.
Assuntos
Placozoa , Animais , Evolução Biológica , Planeta Terra , Filogenia , Placozoa/genéticaRESUMO
There are considerable phylogenetic incongruencies between morphological and phylogenomic data for the deep evolution of animals. This has contributed to a heated debate over the earliest-branching lineage of the animal kingdom: the sister to all other Metazoa (SOM). Here, we use published phylogenomic data sets ($\sim $45,000-400,000 characters in size with $\sim $15-100 taxa) that focus on early metazoan phylogeny to evaluate the impact of incorporating morphological data sets ($\sim $15-275 characters). We additionally use small exemplar data sets to quantify how increased taxon sampling can help stabilize phylogenetic inferences. We apply a plethora of common methods, that is, likelihood models and their "equivalent" under parsimony: character weighting schemes. Our results are at odds with the typical view of phylogenomics, that is, that genomic-scale data sets will swamp out inferences from morphological data. Instead, weighting morphological data 2-10$\times $ in both likelihood and parsimony can in some cases "flip" which phylum is inferred to be the SOM. This typically results in the molecular hypothesis of Ctenophora as the SOM flipping to Porifera (or occasionally Placozoa). However, greater taxon sampling improves phylogenetic stability, with some of the larger molecular data sets ($>$200,000 characters and up to $\sim $100 taxa) showing node stability even with $\geqq100\times $ upweighting of morphological data. Accordingly, our analyses have three strong messages. 1) The assumption that genomic data will automatically "swamp out" morphological data is not always true for the SOM question. Morphological data have a strong influence in our analyses of combined data sets, even when outnumbered thousands of times by molecular data. Morphology therefore should not be counted out a priori. 2) We here quantify for the first time how the stability of the SOM node improves for several genomic data sets when the taxon sampling is increased. 3) The patterns of "flipping points" (i.e., the weighting of morphological data it takes to change the inferred SOM) carry information about the phylogenetic stability of matrices. The weighting space is an innovative way to assess comparability of data sets that could be developed into a new sensitivity analysis tool. [Metazoa; Morphology; Phylogenomics; Weighting.].
Assuntos
Genoma , Genômica , Animais , Genoma/genética , FilogeniaRESUMO
In the midst of only the 6th mass extinction in the Earth's history, we must rethink how we teach evolution to prevent natural selection from being incorrectly used as a biological justification for inaction in the face of today's human-caused mass extinction crisis. Pundits, policy makers, and the general public regularly identify the extinction of endangered species as natural selection at work, rather than attributing modern-day extinction to the sudden catastrophic bad luck of human caused environmental change, a phenomenon distinct from natural selection. In this natural selection framing, the inability of species to survive in human altered environments is the normal progression of "survival of the fittest" and conservation measures designed to protect species is human interference with natural selection. Paradoxically, this erroneous framing of extinction as the normal course of natural selection ignores humanity's exceptional role in causing today's mass extinction crisis. Our examination of this issue in U.S. college students indicates that it arises from misunderstanding the role of extinction in the history of life, leading us to recommend a greater teaching emphasis on the distinction between extinction and natural selection, and on past mass extinction events. Also see the video abstract here https://youtu.be/29VRyirMdiw.
Assuntos
Antropologia/educação , Seleção Genética/genética , Ursidae/genética , Animais , Biodiversidade , Evolução Biológica , Conservação dos Recursos Naturais , Planeta Terra , HumanosRESUMO
ISSUES ADDRESSED: To obtain a baseline of public perception, attitudes and knowledge (PAK) of Australians about microbes, antibiotics and hygiene like hand washing and use of probiotics. METHODS: Using a kiosk-based survey method at the American Museum of Natural History (AMNH), we remotely assayed PAK of Australians through their interaction with the kiosk. The surveys we used had five and seven multiple answer questions and were analysed using standard comparative approaches. We also made comparisons based on gender and on age group for many of the questions. RESULTS: Our analyses indicate that there is a lack of general understanding of the role of microbes in everyday life among Australians. In addition, we detected some basic misunderstandings about antibiotics. While 80% of the respondents identified penicillin as an antibiotic, up to 30% of the respondents wrongly identified aspirin, Tylenol, valium and Benadryl as antibiotics. We also detected a general lack of knowledge about hand washing hygiene and probiotic use. CONCLUSIONS: Our results from around 700 Australian respondents can serve as a baseline for further PAK assessment of Australians. PAK of Australians with respect to microbes and hand washing hygiene is poor therefore public education is needed. This study should stimulate a better roadmap for public education about microbes, antibiotics, probiotics and hygiene. SO WHAT?: With the recent spread of SARS-Cov2 and the ensuing Covid19 pandemic and the continuing rise in antimicrobial resistance, the need for assessment PAK of microbes and infectious disease has become acute.
Assuntos
COVID-19 , Probióticos , Antibacterianos/uso terapêutico , Austrália , Desinfecção das Mãos , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Higiene , Percepção , Probióticos/uso terapêutico , RNA Viral , SARS-CoV-2 , Inquéritos e QuestionáriosRESUMO
Papillomaviruses (PVs) are a heterogeneous group of DNA viruses that can infect fish, birds, reptiles, and mammals. PVs infecting humans (HPVs) phylogenetically cluster into five genera (Alpha-, Beta-, Gamma-, Mu- and Nu-PV), with differences in tissue tropism and carcinogenicity. The evolutionary features associated with the divergence of Papillomaviridae are not well understood. Using a combination of k-mer distributions, genetic metrics, and phylogenetic algorithms, we sought to evaluate the characteristics and differences of Alpha-, Beta- and Gamma-PVs constituting the majority of HPV genomes. A total of 640 PVs including 442 HPV types, 27 non-human primate PV types, and 171 non-primate animal PV types were evaluated. Our analyses revealed the highest genetic diversity amongst Gamma-PVs compared to the Alpha and Beta PVs, suggesting reduced selective pressures on Gamma-PVs. Using a sequence alignment-free trimer (k = 3) phylogeny algorithm, we reconstructed a phylogeny that grouped most HPV types into a monophyletic clade that was further split into three branches similar to alignment-based classifications. Interestingly, a subset of low-risk Alpha HPVs (the species Alpha-2, 3, 4, and 14) split from other HPVs and were clustered with non-human primate PVs. Surprisingly, the trimer-constructed phylogeny grouped the Gamma-6 species types originally isolated from the cervicovaginal region with the main Alpha-HPV clade. These data indicate that characterization of papillomavirus heterogeneity via orthogonal approaches reveals novel insights into the biological understanding of HPV genomes.
Assuntos
DNA Viral/genética , Evolução Molecular , Variação Genética , Genoma Viral/genética , Papillomaviridae/genética , Algoritmos , Animais , Análise por Conglomerados , Códon/genética , Ilhas de CpG/genética , Metilação de DNA , DNA Viral/análise , Humanos , Papillomaviridae/classificação , Papillomaviridae/fisiologia , Infecções por Papillomavirus/virologia , Filogenia , Análise de Sequência de DNA/métodosRESUMO
Recent discoveries on the origins of modern humans from multiple archaic hominin populations and the diversity of human papillomaviruses (HPVs) suggest a complex scenario of virus-host evolution. To evaluate the origin of HPV pathogenesis, we estimated the phylogeny, timing, and dispersal of HPV16 variants using a Bayesian Markov Chain Monte Carlo framework. To increase precision, we identified and characterized non-human primate papillomaviruses from New and Old World monkeys to set molecular clock models. We demonstrate specific host niche adaptation of primate papillomaviruses with subsequent coevolution with their primate hosts for at least 40 million years. Analyses of 212 HPV16 complete genomes and 3582 partial sequences estimated ancient divergence of HPV16 variants (between A and BCD lineages) from their most recent common ancestors around half a million years ago, roughly coinciding with the timing of the split between archaic Neanderthals and modern Homo sapiens, and nearly three times longer than divergence times of modern Homo sapiens. HPV16 A lineage variants were significantly underrepresented in present African populations, whereas the A sublineages were highly prevalent in European (A1-3) and Asian (A4) populations, indicative of viral sexual transmission from Neanderthals to modern non-African humans through multiple interbreeding events in the past 80 thousand years. Remarkably, the human leukocyte antigen B*07:02 and C*07:02 alleles associated with increased risk in cervix cancer represent introgressed regions from Neanderthals in present-day Eurasians. The archaic hominin-host-switch model was also supported by other HPV variants. Niche adaptation and virus-host codivergence appear to influence the pathogenesis of papillomaviruses.
Assuntos
Papillomavirus Humano 16/genética , Papillomavirus Humano 16/patogenicidade , Adaptação Fisiológica/genética , Animais , Evolução Biológica , Evolução Molecular , Fósseis , Variação Genética/genética , Hominidae/imunologia , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/fisiologia , Humanos , Papillomaviridae/genética , Papillomaviridae/patogenicidade , Papillomaviridae/fisiologia , FilogeniaRESUMO
The Hawaiian Drosophila have been a model system for evolutionary, ecological, and ethological studies since the inception of the Hawaiian Drosophila Project in the 1960s. Here we review the past and present research on this incredible lineage and provide a prospectus for future directions on genomics and microbial interactions. While the number of publications on this group has waxed and waned over the years, we assert that recent systematic, biogeographic, and ecological studies have reinvigorated Hawaiian Drosophila as an evolutionary model system. The characteristics that distinguish good model clades from good model organisms (e.g., Drosophila melanogaster) are somewhat different so we first define what constitutes a good evolutionary model. We argue that the Hawaiian Drosophila possess many desired aspects of a good evolutionary model, describe how this group of geographically isolated flies have been used in the past, and propose some exciting avenues for future evolutionary research on this diverse, dynamic clade of Drosophila.
Assuntos
Evolução Biológica , Drosophila melanogaster , Animais , Drosophila , Ecologia , Havaí , FilogeniaRESUMO
BACKGROUND: Innate immunity provides the core recognition system in animals for preventing infection, but also plays an important role in managing the relationship between an animal host and its symbiont. Most of our knowledge about innate immunity stems from a few animal model systems, but substantial variation between metazoan phyla has been revealed by comparative genomic studies. The exploration of more taxa is still needed to better understand the evolution of immunity related mechanisms. Placozoans are morphologically the simplest organized metazoans and the association between these enigmatic animals and their rickettsial endosymbionts has recently been elucidated. Our analyses of the novel placozoan nuclear genome of Trichoplax sp. H2 and its associated rickettsial endosymbiont genome clearly pointed to a mutualistic and co-evolutionary relationship. This discovery raises the question of how the placozoan holobiont manages symbiosis and, conversely, how it defends against harmful microorganisms. In this study, we examined the annotated genome of Trichoplax sp. H2 for the presence of genes involved in innate immune recognition and downstream signaling. RESULTS: A rich repertoire of genes belonging to the Toll-like and NOD-like receptor pathways, to scavenger receptors and to secreted fibrinogen-related domain genes was identified in the genome of Trichoplax sp. H2. Nevertheless, the innate immunity related pathways in placozoans deviate in several instances from well investigated vertebrates and invertebrates. While true Toll- and NOD-like receptors are absent, the presence of many genes of the downstream signaling cascade suggests at least primordial Toll-like receptor signaling in Placozoa. An abundance of scavenger receptors, fibrinogen-related domain genes and Apaf-1 genes clearly constitutes an expansion of the immunity related gene repertoire specific to Placozoa. CONCLUSIONS: The found wealth of immunity related genes present in Placozoa is surprising and quite striking in light of the extremely simple placozoan body plan and their sparse cell type makeup. Research is warranted to reveal how Placozoa utilize this immune repertoire to manage and maintain their associated microbiota as well as to fend-off pathogens.
Assuntos
Genoma/imunologia , Imunidade Inata/genética , Filogenia , Placozoa/imunologia , Animais , Invertebrados/genética , Invertebrados/imunologia , Placozoa/genética , Simbiose/genética , Simbiose/imunologiaRESUMO
Oil palm is the most productive oil-bearing crop. Although it is planted on only 5% of the total world vegetable oil acreage, palm oil accounts for 33% of vegetable oil and 45% of edible oil worldwide, but increased cultivation competes with dwindling rainforest reserves. We report the 1.8-gigabase (Gb) genome sequence of the African oil palm Elaeis guineensis, the predominant source of worldwide oil production. A total of 1.535 Gb of assembled sequence and transcriptome data from 30 tissue types were used to predict at least 34,802 genes, including oil biosynthesis genes and homologues of WRINKLED1 (WRI1), and other transcriptional regulators, which are highly expressed in the kernel. We also report the draft sequence of the South American oil palm Elaeis oleifera, which has the same number of chromosomes (2n = 32) and produces fertile interspecific hybrids with E. guineensis but seems to have diverged in the New World. Segmental duplications of chromosome arms define the palaeotetraploid origin of palm trees. The oil palm sequence enables the discovery of genes for important traits as well as somaclonal epigenetic alterations that restrict the use of clones in commercial plantings, and should therefore help to achieve sustainability for biofuels and edible oils, reducing the rainforest footprint of this tropical plantation crop.
Assuntos
Arecaceae/classificação , Arecaceae/genética , Genoma de Planta/genética , Filogenia , Metabolismo dos Carboidratos/genética , Cromossomos de Plantas/genética , Metabolismo dos Lipídeos/genética , Modelos Genéticos , Dados de Sequência MolecularRESUMO
To determine rates of both symptomatic and asymptomatic infection among ambulatory adults, we collected nasopharyngeal swab specimens, demographic characteristics, and survey information from 1477 adult visitors to a New York City tourist attraction during April-July 2016. Multiplex polymerase chain reaction analysis was used to identify specimens positive for common respiratory viruses. A total of 7.2% of samples tested positive for respiratory viruses; among positive samples, 71.0% contained rhinovirus, and 21.5% contained coronavirus. Influenza virus, respiratory syncytial virus, and parainfluenza virus were also detected. Depending on symptomatologic definition, 57.7%-93.3% of positive samples were asymptomatic. These findings indicate that significant levels of asymptomatic respiratory viral shedding exist during summer among the ambulatory adult population.
Assuntos
Nasofaringe/virologia , Estações do Ano , Eliminação de Partículas Virais/fisiologia , Vírus/isolamento & purificação , Humanos , Reação em Cadeia da Polimerase Multiplex , Cidade de Nova Iorque , Vírus/classificaçãoRESUMO
The Papillomaviridae is a family of small, non-enveloped viruses with double-stranded DNA genomes of 5â748 to 8â607 bp. Their classification is based on pairwise nucleotide sequence identity across the L1 open reading frame. Members of the Papillomaviridae primarily infect mucosal and keratinised epithelia, and have been isolated from fish, reptiles, birds and mammals. Despite a long co-evolutionary history with their hosts, some papillomaviruses are pathogens of their natural host species. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Papillomaviridae, which is available at http://www.ictv.global/report/papillomaviridae.
Assuntos
Genoma Viral , Papillomaviridae/classificação , Papillomaviridae/genética , Animais , Evolução Molecular , Especificidade de HospedeiroRESUMO
Human papillomavirus 58 (HPV58) is found in 10 to 18% of cervical cancers in East Asia but is rather uncommon elsewhere. The distribution and oncogenic potential of HPV58 variants appear to be heterogeneous, since the E7 T20I/G63S variant is more prevalent in East Asia and confers a 7- to 9-fold-higher risk of cervical precancer and cancer. However, the underlying genomic mechanisms that explain the geographic and carcinogenic diversity of HPV58 variants are still poorly understood. In this study, we used a combination of phylogenetic analyses and bioinformatics to investigate the deep evolutionary history of HPV58 complete genome variants. The initial splitting of HPV58 variants was estimated to occur 478,600 years ago (95% highest posterior density [HPD], 391,000 to 569,600 years ago). This divergence time is well within the era of speciation between Homo sapiens and Neanderthals/Denisovans and around three times longer than the modern Homo sapiens divergence times. The expansion of present-day variants in Eurasia could be the consequence of viral transmission from Neanderthals/Denisovans to non-African modern human populations through gene flow. A whole-genome sequence signature analysis identified 3 amino acid changes, 16 synonymous nucleotide changes, and a 12-bp insertion strongly associated with the E7 T20I/G63S variant that represents the A3 sublineage and carries higher carcinogenetic potential. Compared with the capsid proteins, the oncogenes E7 and E6 had increased substitution rates indicative of higher selection pressure. These data provide a comprehensive evolutionary history and genomic basis of HPV58 variants to assist further investigation of carcinogenic association and the development of diagnostic and therapeutic strategies.IMPORTANCE Papillomaviruses (PVs) are an ancient and heterogeneous group of double-stranded DNA viruses that preferentially infect the cutaneous and mucocutaneous epithelia of vertebrates. Persistent infection by specific oncogenic human papillomaviruses (HPVs), including HPV58, has been established as the primary cause of cervical cancer. In this work, we reveal the complex evolutionary history of HPV58 variants that explains the heterogeneity of oncogenic potential and geographic distribution. Our data suggest that HPV58 variants may have coevolved with archaic hominins and dispersed across the planet through host interbreeding and gene flow. Certain genes and codons of HPV58 variants representing higher carcinogenic potential and/or that are under positive selection may have important implications for viral host specificity, pathogenesis, and disease prevention.
Assuntos
Evolução Molecular , Variação Genética , Papillomaviridae/classificação , Papillomaviridae/genética , Infecções por Papillomavirus/virologia , Proteínas do Capsídeo/genética , Genoma Viral , Humanos , Filogenia , Seleção GenéticaRESUMO
BACKGROUND: The persistent and growing gap between the availability of sequenced genomes and the ability to assign functions to sequenced genes led us to explore ways to maximize the information content of automated annotation for studies of anopheline mosquitos. Specifically, we use genome content analysis of a large number of previously sequenced anopheline mosquitos to follow the loss and gain of protein families over the evolutionary history of this group. The importance of this endeavor lies in the potential for comparative genomic studies between Anopheles and closely related non-vector species to reveal ancestral genome content dynamics involved in vector competence. In addition, comparisons within Anopheles could identify genome content changes responsible for variation in the vectorial capacity of this family of important parasite vectors. RESULTS: The competence and capacity of P. falciparum vectors do not appear to be phylogenetically constrained within the Anophelinae. Instead, using ancestral reconstruction methods, we suggest that a previously unexamined component of vector biology, anopheline nucleotide metabolism, may contribute to the unique status of anophelines as P. falciparum vectors. While the fitness effects of nucleotide co-option by P. falciparum parasites on their anopheline hosts are not yet known, our results suggest that anopheline genome content may be responding to selection pressure from P. falciparum. Whether this response is defensive, in an attempt to redress improper nucleotide balance resulting from P. falciparum infection, or perhaps symbiotic, resulting from an as-yet-unknown mutualism between anophelines and P. falciparum, is an open question that deserves further study. CONCLUSIONS: Clearly, there is a wealth of functional information to be gained from detailed manual genome annotation, yet the rapid increase in the number of available sequences means that most researchers will not have the time or resources to manually annotate all the sequence data they generate. We believe that efforts to maximize the amount of information obtained from automated annotation can help address the functional annotation deficit that most evolutionary biologists now face, and here demonstrate the value of such an approach.
Assuntos
Anopheles/genética , Genoma de Inseto , Insetos Vetores/genética , Malária Falciparum/parasitologia , Plasmodium falciparum/genética , Animais , Anopheles/classificação , Mapeamento Cromossômico , Interações Hospedeiro-Patógeno/genética , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Malária Falciparum/patologia , Nucleotídeos/metabolismo , FilogeniaRESUMO
In order to complete their life cycle, papillomaviruses have evolved to manipulate a plethora of cellular pathways. The products of the human Alphapapillomavirus E6 proteins specifically interact with and target PDZ containing proteins for degradation. This viral phenotype has been suggested to play a role in viral oncogenesis. To analyze the association of HPV E6 mediated PDZ-protein degradation with cervical oncogenesis, a high-throughput cell culture assay was developed. Degradation of an epitope tagged human MAGI1 isoform was visualized by immunoblot. The correlation between HPV E6-induced degradation of hMAGI1 and epidemiologically determined HPV oncogenicity was evaluated using a Bayesian approach within a phylogenetic context. All tested oncogenic types degraded the PDZ-containing protein hMAGI1d; however, E6 proteins isolated from several related albeit non-oncogenic viral types were equally efficient at degrading hMAGI1. The relationship between both traits (oncogenicity and PDZ degradation potential) is best explained by a model in which the potential to degrade PDZ proteins was acquired prior to the oncogenic phenotype. This analysis provides evidence that the ancestor of both oncogenic and non-oncogenic HPVs acquired the potential to degrade human PDZ-containing proteins. This suggests that HPV E6 directed degradation of PDZ-proteins represents an ancient ecological niche adaptation. Phylogenetic modeling indicates that this phenotype is not specifically correlated with oncogenic risk, but may act as an enabling phenotype. The role of PDZ protein degradation in HPV fitness and oncogenesis needs to be interpreted in the context of Alphapapillomavirus evolution.
Assuntos
Adaptação Biológica/fisiologia , Transformação Celular Viral/fisiologia , Proteínas Oncogênicas Virais/metabolismo , Domínios PDZ/fisiologia , Infecções por Papillomavirus/metabolismo , Alphapapillomavirus/genética , Alphapapillomavirus/metabolismo , Evolução Biológica , Linhagem Celular Tumoral , Humanos , Proteínas Oncogênicas Virais/genética , Papillomaviridae/genética , Papillomaviridae/metabolismo , Infecções por Papillomavirus/genética , FilogeniaRESUMO
Construction of stringent gene content matrices was accomplished for 21 Anopheline mosquito species and strains and four outgroups species. The presence absence matrix using e-75 as a cutoff in single linkage clustering had over 17,000 ortholog groups. We used the gene content matrix to generate a phylogenetic hypothesis that is in general agreement with gene sequence based phylogenies. In addition to establishing a congruent gene content phylogeny we examined the consistency of three methods for analyzing presence absence data - unweighted parsimony, dollo parsimonly and maximum likelihood using a BINGAMMA model. An examination of the chromosomal location of the gains and losses in the presence absence matrix revealed a low frequency of gains and losses at centromeres and tips of chromosomes.