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PubMed1997

The Bag320 satellite DNA family in Bacillus stick insects (Phasmatodea): different rates of molecular evolution of highly repetitive DNA in bisexual and parthenogenic taxa.

The Bag320 satellite DNA (satDNA) family was studied in seven populations of the stick insects Bacillus atticus (parthenogenetic, unisexual) and Bacillus grandii (bisexual). It was characterized as widespread in all zymoraces of B. atticus and in all subspecies of B. grandii. The copy number of this satellite is higher in the bisexual B. grandii (15%-20% of the genome) than in the parthenogenetic B. atticus (2%-5% of the genome). The nucleotide sequences of 12 Bag320 clones from B. atticus and 17 from B. grandii differed at 13 characteristic positions by fixed nucleotide substitutions. Thus, nucleotide sequences from both species cluster conspecifically in phylogenetic dendrograms. The nucleotide sequences derived from B. grandii grandii could be clearly discriminated from those of B. grandii benazzii and B. grandii maretimi on the basis of 25 variable sites, although all taxa come from Sicily. In contrast, the Bag320 sequences from B. atticus could not be discriminated accordingly, although they derive from geographically quite distant populations of its three zymoraces (the Italian and Greek B. atticus atticus, the Greek and Turkish B. atticus carius, and the Cyprian B. atticus cyprius). The different rate of evolutionary turnover of the Bag320 satDNA in both species can be related to their different modes of reproduction. This indicates that meiosis and chromosome segregation affect processes in satDNA diversification.

Animals↗
PubMedDate not supplied

Career paths of geriatric nurse practitioners employed in nursing homes.

The career paths of geriatric nurse practitioners (GNPs) trained with support from the W. K. Kellogg Foundation through the Mountain States Health Corporation (MSHC) were studied. Under this program, GNPs were recruited from sponsoring nursing homes and returned to GNP positions in the sponsoring facilities following training. Training was carried out under a continuing education model offered through six university-based schools of nursing. Questionnaires were sent to the 111 GNPs trained. Of the 102 respondents, 97 provided complete information about past and present education, work experience, and job functions. The GNPs were women with a median age of 45 years, and they were employed in rural settings in the western United States. More than 45 percent of the nurses had at least a baccalaureate degree at the time of GNP training. The GNPs remained employed in long-term care positions that implemented the practitioner role. The median length of GNP employment in their first jobs after training was more than 4.5 years. The resignation rate from this first position was 1.66 resignations for each 10 years of GNP employment. Job changes were likely to be attributed to organizational changes with subsequent positions shifting toward a diversification of the GNP role. The study demonstrates the success of the MSHC program in introducing and retaining GNPs in nursing homes.

Career Mobility↗
PubMed2005

Origin and evolution of viruses causing classical swine fever in Cuba.

We have analyzed the origin and evolution of viruses from the classical swine fever (CSF) epidemic that affects Cuba since 2001 by nucleotide sequencing of regions within the E2 glycoprotein and the NS5B (polymerase) genes. The sequence of 190 nucleotides from E2 gene was determined for 10 CSF viruses isolated at different locations of the island, and used for phylogenetic analyses, including sequences from viruses of the 1993--1997 epizootic, previously determined, as well as those from representatives of the different CSFV genotypes. The phylogenetic tree obtained indicates that viruses circulating at present belong to the subgroup 1.2 and are closely related to those isolated during the 1993--1997 epizootic, including the strain Margarita used for vaccine potency tests in Cuba. However, the pattern of evolution revealed by these analyses was different than that observed previously, in which western isolates were almost identical to Margarita strain, while eastern isolates showed a higher level of genetic diversification. In this case, all the viruses analyzed grouped in an independent, define cluster that is closely related, albeit distinguishable, from that of Margarita-related viruses that previously circulated in the western part of Cuba. In addition, the 2001--2003 viruses showed a branched pattern with a level of sequence diversification similar to that observed in the eastern 1993--1997 viruses. Interestingly, a significant fraction (about 54%) of the mutations found in the E2 sequence led to amino acid replacements. This high rate of non-synonymous mutations was not found in the previous Cuban epizootic and has not been reported for other CSF outbreaks. In spite of these amino acid replacements, no antigenic changes were observed in the reactivity of different isolates with CSFV-specific MAbs and polyclonal sera. The phylogenetic tree derived from 409 nucleotides of NS5B gene of seven isolates and Margarita strain, was consistent with that obtained from E2 sequences. In this region, encoding a non-structural protein, a low level of fixation of non-synonymous mutations was observed. The results obtained suggests that epidemiological factors affecting CSFV spread during the current epizootic in Cuba can favour the fixation of non-synonymous mutation in the E2 gene, which could be associated with a lower severity in the clinical signs developed by most of the affected animals.

Amino Acid Sequence↗
PubMed1998

The impact of the Community Care Act: views from the independent sector.

The 1990 NHS and Community Care Act introduced changes that had significant implications for independent service providers. The legislation was intended to decrease unnecessary institutionalization, increase the demand for non-statutory community care services, and improve collaboration between the private and public service sectors. Preliminary evidence on the impact of the Act suggests that the principal changes related to private service provision have not been translated into practice, but the data are confined to studies from the local authorities' perspective or that of carers. In this paper, the views of independent service providers in an urban area of Scotland were examined through interviews with 24 administrators of nursing homes or residential care facilities. The study investigated their perceptions of the impact of the law on institutionalization, diversification into community care, and partnerships between the public and private spheres. The findings show that facilities have experienced a range of problems since the law came into effect, including higher vacancy rates, more disabled residents, delays in admissions, cash flow problems and reductions in private pay patients. Those owned by public limited companies were more able to buffer themselves from the adverse effects. A large proportion of the facilities had diversified into community based long-term care, but these were perceived as a minor sideline. Finally, the legislation did not result in links forged between independent service providers and the social service departments of local authorities who are charged with assessing, coordinating and purchasing long-term care.

Journal Article↗
PubMed2004

Molecular phylogeny, historical biogeography, and divergence time estimates for swallowtail butterflies of the genus Papilio (Lepidoptera: Papilionidae).

Swallowtail butterflies are recognized as model organisms in ecology, evolutionary biology, genetics, and conservation biology but present numerous unresolved phylogenetic problems. We inferred phylogenetic relationships for 51 of about 205 species of the genus Papilio (sensu lato) from 3.3-Kilobase (kb) sequences of mitochondrial and nuclear DNA (2.3 kb of cytochrome oxidases I and II and 1.0 kb of elongation factor 1 alpha). Congruent phylogenetic trees were recovered within Papilio from analyses of combined data using maximum likelihood, Bayesian analysis, and maximum parsimony bootstrap consensus. Several disagreements with the traditional classification of Papilio were found. Five major previously hypothesized subdivisions within Papilio were well supported: Heraclides, Pterourus, Chilasa, Papilio (sensu stricto), and Eleppone. Further studies are required to clarify relationships within traditional "Princeps," which was paraphyletic. Several biologically interesting characteristics of Papilio appear to have polyphyletic origins, including mimetic adults, larval host associations, and larval morphology. Early diversification within Papilio is estimated at 55-65 million years ago based on a combination of biogeographic time constraints rather than fossils. This divergence time suggests that Papilio has slower apparent substitution rates than do Drosophila and fig-pollinating wasps and/or divergences corrected using best-fit substitution models are still being consistently underestimated. The amount of sequence divergence between Papilio subdivisions is equivalent to divergences between genera in other tribes of the Papilionidae, and between genera of moths of the noctuid subfamily Heliothinae.

Animals↗
PubMed1993

Medicare prospective payment reforms and hospital utilization. Temporary or lasting effects?

Early evaluations of the Medicare prospective payment reforms found them very effective in reducing hospital utilization. In this study, the author investigated whether the reforms remained effective throughout the first decade of implementation. Seasonal autoregressive-integrated-moving average (ARIMA) models with intervention components were applied to age-specific national times series of hospital admissions, average length of stay, inpatient days, and adjusted inpatient days. Three alternative regulatory impact patterns were tested using quarterly data collected by the National Hospital Panel Survey spanning the period 1970:1 to 1992:1 (n = 89). The reimbursement reforms seem to have reduced hospital admissions, average length of stay and patient days during fiscal years 1983-1984, but significant readjustments relative to projected levels occurred for all four utilization measures during fiscal years 1985-1986. Similar, yet less pronounced readjustments, were found in the analysis of non-Medicare time series suggesting regulatory spill-over effects. Sicker patients and hospital diversification efforts are two plausible reasons for the relative increase in hospital utilization during 1985-1986. The Medicare reimbursement reforms appear to remain effective in reducing hospital utilization, but at a reduced rate.

Aged↗
PubMed2006

Molecular phylogeny and a chronology of diversification for "phractocephaline" catfishes (Siluriformes: Pimelodidae) based on mitochondrial DNA and nuclear recombination activating gene 2 sequences.

The Maracaibo basin in northwestern Venezuela is home to over 108 species of freshwater fishes, over half of which occur nowhere else. The rise of the Mérida Andes between 8 and 10 million years ago is believed to have divided a preexisting biota and facilitated allopatric speciation. The distinctive "phractocephaline" clade of pimelodid catfishes has a distribution that includes the Maracaibo historically and today is represented by Perrunichthys (Maracaibo endemic), Leiarius, Phractocephalus, and Steindachneridion. A resolved and well-supported phylogeny was obtained from the phylogenetic analysis of over 3.4kb (including cytochrome b, NADH dehydrogenase subunit 1, recombination activating gene subunit 2). Rates of divergence among "phractocephalines" were calibrated with fossil material and the Mérida uplift. These independent calibrators provided different node-age estimates when the rates were applied separately to the gene partitions (mtDNA and rag2). Node-age discrepancies were particularly evident at older nodes. This is due to two factors: (1) multiple substitution of mtDNA underestimates the amount of change and therefore time since cladogenesis, whereas (2) calibration of an ancient node with fossils produces an artificially slow rate (due to the masking of divergence through multiple substitution) that overestimates time when applied to younger nodes. Node-age estimates provided by the more slowly evolving rag2 sequences were more consistent with other sources of historical inference, e.g., paleogeography and the fossil record. Given these points, we provide a synthetic chronology of diversification and discuss the reasons for its preference. The phylogeny and synthetic chronology suggest Perrunichthys perruno (Maracaibo endemic) and Leiarius pictus (Orinoco and Guianas) to be a vicariant species pair that last shared a common ancestor during the period of Mérida uplift.

Animals↗
PubMed2000

Testing macro-evolutionary models using incomplete molecular phylogenies.

Phylogenies reconstructed from gene sequences can be used to investigate the tempo and mode of species diversification. Here we develop and use new statistical methods to infer past patterns of speciation and extinction from molecular phylogenies. Specifically, we test the null hypothesis that per-lineage speciation and extinction rates have remained constant through time. Rejection of this hypothesis may provide evidence for evolutionary events such as adaptive radiations or key adaptations. In contrast to previous approaches, our methods are robust to incomplete taxon sampling and are conservative with respect to extinction. Using simulation we investigate, first, the adverse effects of failing to take incomplete sampling into account and, second, the power and reliability of our tests. When applied to published phylogenies our tests suggest that, in some cases, speciation rates have decreased through time.

Algorithms↗
PubMed1997

Slower evolution of human immunodeficiency virus type 1 quasispecies during progression to AIDS.

The evolution of human immunodeficiency virus type 1 (HIV-1) quasispecies at the envelope gene was studied from the time of infection in 11 men who experienced different rates of CD4+ cell count decline and 6 men with unknown dates of infection by using DNA heteroduplex mobility assays. Quasispecies were genetically homogeneous near the time of seroconversion. Subsequently, slower proviral genetic diversification and higher plasma viremia correlated with rapid CD4+ cell count decline. Except for the fastest progressors to AIDS, highly diverse quasispecies developed in all subjects within 3 to 4 years. High quasispecies diversity was then maintained for years until again becoming more homogeneous in a subset of late-stage AIDS patients. Individuals who maintained high CD4+ cell counts showed continuous genetic turnover of their complex proviral quasispecies, while more closely related sets of variants were found in longitudinal samples of severely immunocompromised patients. The limited number of variants that grew out in short-term PBMC cocultures were rare in the uncultured proviral quasispecies of healthy, long-term infected individuals but more common in vivo in patients with low CD4+ cell counts. The slower evolution of HIV-1 observed during rapid progression to AIDS and in advanced patients may reflect ineffective host-mediated selection pressures on replicating quasispecies.

Acquired Immunodeficiency Syndrome↗
PubMed2004

Genetic analysis of rice varietal diversity for rice blast control.

Two Indica hybrid rice of Shanyou63 (A) and Shanyou22 (B), two glutinous landraces of Huanghenuo (C) and Zinuo (D) and three improved Japonica rice of Hexi41 (E), Chujing12 (F) and 8126 (G) were selected and their genetic resistance relationship was estimated using resistance gene analogue (RGA). The results showed that there were similar genetic relationships between hybrid varieties at the genetic similarity (GS) of 0.86,and among improved Japonica varieties at the GS of 0.84, while highly genetic diversifications between traditional varieties, Indica and Japonica varieties, traditional and modern variety ( GS:0.45). The results also showed that clustering analysis based on RGA data were generally corresponded to known pedigrees and blast field resistances of the varieties. Based on varietal differences in RGA data and agronomic traits, plot experiments of five mixed-planting combinations of A/C, A/D, B/C, B/D and A/B and two combinations of E/C and E/F/G were conducted in Jianshui and Shiping counties ( Indica rice growing region) and Luxi County (warm Japonica region) in Yunnan Province in past two years, respectively. The results demonstrated that rice blast management was more effective in five mixed-planting combinations of varieties with different genetic backgrounds (GS: 0.45-0.77) than in two combinations with similar genetic relationships (GS: 0.84-0.90), compared with their monocultures. It is evident for the highly susceptible landraces in mixed-planting to achieve disease control, with significant decreases both in incidence and severity. The blast control efficiencies of landraces in different mixture combinations reached to 54.47%-92.18%. The control efficiencies of improved varieties varied from 15.12% to 25.54% in mixture combinations with closed genetic relationship. In addition,the total yield of 5 varietal combinations with distant genetic relationship increased 539.0-904.0 kg/ha in the mixed-planting plots, at increase rates of 5.6%-10.2%. Mixed rice varieties with similar genetic background did not achieve significant yield increase. Otherwise, the yield of E/F/G decreased 2.7%-4.0% compared with pure stand. The results can provide scientific basis of varietal combinations in diversification experiments for blast control.

Genetic Variation↗
PubMed2000

Ordovician eunicid polychaetes of Estonia and surrounding areas: review of their distribution and diversification.

Scolecodonts, the jaws of polychaete worms, are common and diverse palynomorphs in the Ordovician rocks of Estonia and surrounding areas. Some 120 apparatus-based species representing about 40 genera have been recorded thus far. Relatively long stratigraphical ranges of the majority of species reflect a low rate of evolution of jawed polychaetes. However, some individual species, as well as structural changes in the assemblages, appear to be useful for stratigraphical purposes. Environmental events like those in the middle Caradoc and late Ashgill had some impact on polychaete faunas, but less than on several other groups. In order to study the spatial distribution of eunicids, faunas of particular intervals of the Ordovician were investigated. Quantitative analysis revealed that polychaete assemblages with a very consistent qualitative and quantitative composition were widespread over long distances within the belts of similar facies conditions in the Baltoscandian Palaeobasin. On the other hand, it appears that species of Ordovician jawed polychaetes were strongly influenced by particular facies, and accordingly well differentiated along the palaeobasin gradient. The decrease in diversity and abundance towards the deeper-water part of the palaeobasin indicates that the majority of Ordovician eunicids preferred relatively shallow-water conditions. The increase in differentiation of environments is accompanied by an increase in differentiation of polychaete assemblages.

Journal Article↗
PubMed2006

Evolutionary selective trends of insect/mosquito antimicrobial defensin peptides containing cysteine-stabilized alpha/beta motifs.

Insect defensins containing cysteine-stabilized alpha/beta motifs (Cs-alpha/beta defensin) are cationic, inducible antibacterial peptides involved in humoral defence against pathogens. To examine trends in molecular evolution of these antimicrobial peptides, sequences similar to the well-characterized Cs-alpha/beta defensin peptide of Anopheles gambiae, using six cysteine residues as landmarks, were retrieved from genomic and protein databases. These sequences were derived from different orders of insects. Genes of insect Cs-alpha/beta defensin appear to constitute a multigene family in which the copy number varies between insect species. Phylogenetic analysis of these sequences revealed two main lineages, one group comprising mainly lepidopteran insects and a second, comprising Hemiptera, Coleoptera, Diptera and Hymenoptera insects. Moreover, the topology of the phylogram indicated dipteran Cs-alpha/beta defensins are diverse, suggesting diversity in immune mechanisms in this order of insects. Overall evolutionary analysis indicated marked diversification and expansion of mature defensin isoforms within the species of mosquitoes relative to non-mosquito defensins, implying the presence of finely tuned immune responses to counter pathogens. The observed higher synonymous substitution rate relative to the nonsynonymous rate in almost all the regions of Cs-alpha/beta defensin of mosquitoes suggests that these peptides are predominately under purifying selection. The maximum-likelihood models of codon substitution indicated selective pressure at different amino acid sites in mosquito mature Cs-alpha/beta defensins is differ and are undergoing adaptive evolution in comparison to non-mosquito Cs-alpha/beta defensins, for which such selection was inconspicuous; this suggests the acquisition of selective advantage of the Cs-alpha/beta defensins in the former group. Finally, this study represents the most detailed report on the evolutionary strategies of Cs-alpha/beta defensins of mosquitoes in particular and insects in general, and indicates that insect Cs-alpha/beta defensins have evolved by duplication followed by divergence, to produce a diverse set of paralogues.

Amino Acid Motifs↗
PubMed2004

Coalescent processes and relaxation of selective constraints leading to contrasting genetic diversity at paralogs AtHVA22d and AtHVA22e in Arabidopsis thaliana.

Duplicate loci offer a very powerful system for understanding the complicated genome structure and adaptive evolution of a gene family. In this study, the genetic variation at paralogs AtHVA22d and AtHVA22e, members of an ABA- and stress-inducible gene family, is examined in the selfing Arabidopsis thaliana. Population genetic analysis indicates contrasting levels of nucleotide diversity at overall exon sequence and nonsynonymous sites between AtHVA22d (pi = 0.00337, pi(rep) = 0.00158) and AtHVA22e (pi = 0.00054, pi(rep) = 0.00023). The fact of Ka/Ks ratios significantly less than 1 in all sequences indicates that both genes are functional and subjected to purifying selection. In addition, rooted at barley HVA22, accelerated evolution is detected at replacement changes in the AtHVA22d locus, indicating relaxation of purifying selection after gene duplication. However, relative rate tests reveal no deviation from the neutrality at synonymous sites between the two paralogs. Based on clock-like evolution, the rate of synonymous substitution is estimated at 1.83 x 10(-9) substitutions per site per year; and the divergence of the two paralogs is traced to 90 MYA, coinciding with a period of the diversification of angiosperms. Given no codon usage bias in both genes, natural selection alone cannot account for the 6.4-fold differences in the nucleotide variation at synonymous sites between the two paralogs. Random processes resulting in different coalescence times, 3.65 MYA at AtHVA22d vs. 1.20 MYA at AtHVA22e, may have predominantly contributed to the evident differences of the genetic diversity. Partially nonoverlapping modes of expression between the two functional paralogs suggest a subfunctionalization hypothesis for explaining the fates of duplicate loci.

Arabidopsis↗
PubMed2003

The nature of introns 4-6 suggests reduced lineage specificity in HLA-B alleles.

For most HLA-B alleles, coding sequences of the 3' part of the genes still need to be determined, and sequences of the 3' noncoding regions have yet to be studied systematically. In this study, we have determined the sequences of introns 4-6 in all HLA-B allelic groups, and computed nucleotide substitution rates and phylogenetic relationships. These sequences demonstrated an inconsistent pattern of intralineage specificity, intralineage diversity, and interlineage diversity that is best characterized by a patchwork pattern. Apart from phylogenetic studies about HLA diversity and diversification, the sequence data obtained in our study may prove valuable for haplotype-specific sequencing of the 3' part of HLA-B and for the explanation of recombination events in newly described HLA-B alleles.

Alleles↗
PubMed2003

Definition and empirical characterization of creative processes.

Creative processes exhibit a new, thus far unrecognized, form of dynamical behavior distinct from the known classes of mechanical and chaotic dynamics. We present quantitative methods of time series analysis that distinguish creative processes from random and chaotic systems. Creative processes exhibit diversification, indicating an expanding phase space volume, which contrasts with processes that converge to equilibrium, or to periodic or chaotic attractors. Creative processes exhibit novelty, that is, they produce less recurrence than obtains from random series. Creative processes exhibit arrangement, a measure of patterned recurrences that indicates nonrandom complexity. These three measures, diversification, novelty, and arrangement, reliably identify creative dynamics and distinguish creativity from chaos and from randomness.

Affect↗
PubMed1998

Organizational diversification in the American hospital.

This paper outlines a conceptual framework of organizational diversification and assesses the state of empirical research on hospital organizational change. The literature on economic organization of hospitals, one of the most developed branches of health services research, still has only weak ties to economic theory. Evolving physician-hospital organizations do not fit into existing frameworks based on horizontal integration, vertical integration, or diversification. Empirical research has primarily focused on horizontal integration, and cause-effect relationships are often obscured by models that depart from economic theory and lack controls for self-selection bias. Recent empirical studies indicate that hospital mergers had moderate, rather than dramatic, effects on the rate of change in operating costs, staffing, and scale. Mergers rarely resulted in hospital closure, but were as likely to result in acute care consolidation and restructuring as in conversion to non-acute inpatient uses. While administrative costs were higher in for-profit than non-profit system hospitals, total costs were similar. System hospitals had lower marginal and average costs per stay than independent hospitals. Hospital vertical integration into subacute care was largely an artifact of the governmental uniform pricing system, which encouraged vertical integration. Hospitals that shared governance or financial risks with physicians outperformed those with high levels of physician governance and financial integration (e.g. stock ownership). Formal physician-hospital organizational arrangements often served to coordinate managed care contracting or to forge links with primary care group practices. Hospital diversification into related services improved short-term financial performance over unrelated diversification, although long-term performance was similar.

Delivery of Health Care, Integrated↗
PubMed2002

The evolution of gene duplicates.

Gene and genome duplications have given rise to enormous variability among species in the number of genes within their genomes. Gene copies have in turn played important roles in adaptation, having been implicated in the evolution of the immune response, insecticide resistance, efficient protein synthesis, and vertebrate body plans. In this chapter, we discuss the life history of gene duplications, from their first appearance within a population, through the period during which they rise in frequency or disappear, to their long-term fate. At each phase, we discuss the evolutionary processes that have influenced the dynamics of gene duplications and shaped their ultimate roles within a population. We argue that there is no evidence that organisms have evolved strategies to promote gene duplication in order to permit adaptive evolution. In contrast, many mechanisms exist to silence or eliminate duplicated genes, suggesting that selection has acted largely to reduce the rate of gene duplication. We also argue that natural selection has functioned as an effective sieve, increasing the representation of beneficial gene duplicates among those that establish within a population and that play a long-term role in evolution. To refine our understanding of how selection acts on new gene duplications, we provide a model incorporating a single-copy gene, its gene duplicate, and selection either favoring heterozygotes or eliminating deleterious mutations. Although both forms of selection can increase the initial rate of spread of a gene duplicate, the efficacy with which they do so differs dramatically. Heterozygote advantage always increases the rate of spread and can have a large impact. In contrast, masking deleterious mutations never has a large effect on the rate of spread of the duplicate, and this minor effect can be negative as well as positive. In both cases, the degree of linkage between the two gene copies affects the rate of spread of the duplication. Finally, we discuss evolutionary processes that occur over longer periods after a gene duplication has become established within a population. These long-term processes include maintenance, inactivation, and diversification in function. Consideration of each of the short-term and long-term processes affecting duplicated genes illustrates the subtle ways in which selection has acted to shape genomic structure.

Animals↗
PubMed2006

That awkward age for butterflies: insights from the age of the butterfly subfamily Nymphalinae (Lepidoptera: Nymphalidae).

The study of the historical biogeography of butterflies has been hampered by a lack of well-resolved phylogenies and a good estimate of the temporal span over which butterflies have evolved. Recently there has been surge of phylogenetic hypotheses for various butterfly groups, but estimating ages of divergence is still in its infancy for this group of insects. The main problem has been the sparse fossil record for butterflies. In this study I have used a surprisingly good fossil record for the subfamily Nymphalinae (Lepidoptera: Nymphalidae) to estimate the ages of diversification of major lineages using Bayesian relaxed clock methods. I have investigated the effects of varying priors on posterior estimates in the analyses. For this data set, it is clear that the prior of the rate of molecular evolution at the ingroup node had the largest effect on the results. Taking this into account, I have been able to arrive at a plausible history of lineage splits, which appears to be correlated with known paleogeological events. The subfamily appears to have diversified soon after the K/T event about 65 million years ago. Several splits are coincident with major paleogeological events, such as the connection of the African and Asian continents about 21 million years ago and the presence of a peninsula of land connecting the current Greater Antilles to the South American continent 35 to 33 million years ago. My results suggest that the age of Nymphalidae is older than the 70 million years speculated to be the age of butterflies as a whole.

Animals↗