A determinação dos números de indivíduos mínimos necessários na experimentação genética

The main object of the present paper consists in giving formulas and methods which enable us to determine the minimum number of repetitions or of individuals necessary to garantee some extent the success of an experiment. The theoretical basis of all processes consists essentially in the following. Knowing the frequency of the desired p and of the non desired ovents q we may calculate the frequency of all possi- ble combinations, to be expected in n repetitions, by expanding the binomium (p-+q)n. Determining which of these combinations we want to avoid we calculate their total frequency, selecting the value of the exponent n of the binomium in such a way that this total frequency is equal or smaller than the accepted limit of precision n/pª{ 1/n1 (q/p)n + 1/(n-1)| (q/p)n-1 + 1/ 2!(n-2)| (q/p)n-2 + 1/3(n-3) (q/p)n-3... < Plim - -(1b) There does not exist an absolute limit of precision since its value depends not only upon psychological factors in our judgement, but is at the same sime a function of the number of repetitions For this reasen y have proposed (1,56) two relative values, one equal to 1-5n as the lowest value of probability and the other equal to 1-10n as the highest value of improbability, leaving between them what may be called the "region of doubt However these formulas cannot be applied in our case since this number n is just the unknown quantity. Thus we have to use, instead of the more exact values of these two formulas, the conventional limits of P.lim equal to 0,05 (Precision 5%), equal to 0,01 (Precision 1%, and to 0,001 (Precision P, 1%). The binominal formula as explained above (cf. formula 1, pg. 85), however is of rather limited applicability owing to the excessive calculus necessary, and we have thus to procure approximations as substitutes. We may use, without loss of precision, the following approximations: a) The normal or Gaussean distribution when the expected frequency p has any value between 0,1 and 0,9, and when n is at least superior to ten. b) The Poisson distribution when the expected frequecy p is smaller than 0,1. Tables V to VII show for some special cases that these approximations are very satisfactory. The praticai solution of the following problems, stated in the introduction can now be given: A) What is the minimum number of repititions necessary in order to avoid that any one of a treatments, varieties etc. may be accidentally always the best, on the best and second best, or the first, second, and third best or finally one of the n beat treatments, varieties etc. Using the first term of the binomium, we have the following equation for n: n = log Riim / log (m:) = log Riim / log.m - log a --------------(5) B) What is the minimun number of individuals necessary in 01der that a ceratin type, expected with the frequency p, may appaer at least in one, two, three or a=m+1 individuals. 1) For p between 0,1 and 0,9 and using the Gaussean approximation we have: on - ó. p (1-p) n - a -1.m b= δ. 1-p /p e c = m/p } -------------------(7) n = b + b² + 4 c/ 2 n´ = 1/p n cor = n + n' ---------- (8) We have to use the correction n' when p has a value between 0,25 and 0,75. The greek letters delta represents in the present esse the unilateral limits of the Gaussean distribution for the three conventional limits of precision : 1,64; 2,33; and 3,09 respectively. h we are only interested in having at least one individual, and m becomes equal to zero, the formula reduces to : c= m/p o para a = 1 a = { b + b²}² = b² = δ2 1- p /p }-----------------(9) n = 1/p n (cor) = n + n´ 2) If p is smaller than 0,1 we may use table 1 in order to find the mean m of a Poisson distribution and determine. n = m: p C) Which is the minimun number of individuals necessary for distinguishing two frequencies p1 and p2? 1) When pl and p2 are values between 0,1 and 0,9 we have: n = { δ p1 ( 1-pi) + p2) / p2 (1 - p2) n= 1/p1-p2 }------------ (13) n (cor) We have again to use the unilateral limits of the Gaussean distribution. The correction n' should be used if at least one of the valors pl or p2 has a value between 0,25 and 0,75. A more complicated formula may be used in cases where whe want to increase the precision : n (p1 - p2) δ { p1 (1- p2 ) / n= m δ = δ p1 ( 1 - p1) + p2 ( 1 - p2) c= m / p1 - p2 n = { b2 + 4 4 c }2 }--------- (14) n = 1/ p1 - p2 2) When both pl and p2 are smaller than 0,1 we determine the quocient (pl-r-p2) and procure the corresponding number m2 of a Poisson distribution in table 2. The value n is found by the equation : n = mg /p2 ------------- (15) D) What is the minimun number necessary for distinguishing three or more frequencies, p2 p1 p3. If the frequecies pl p2 p3 are values between 0,1 e 0,9 we have to solve the individual equations and sue the higest value of n thus determined : n 1.2 = {δ p1 (1 - p1) / p1 - p2 }² = Fiim n 1.2 = { δ p1 ( 1 - p1) + p1 ( 1 - p1) }² } -- (16) Delta represents now the bilateral limits of the : Gaussean distrioution : 1,96-2,58-3,29. 2) No table was prepared for the relatively rare cases of a comparison of threes or more frequencies below 0,1 and in such cases extremely high numbers would be required. E) A process is given which serves to solve two problemr of informatory nature : a) if a special type appears in n individuals with a frequency p(obs), what may be the corresponding ideal value of p(esp), or; b) if we study samples of n in diviuals and expect a certain type with a frequency p(esp) what may be the extreme limits of p(obs) in individual farmlies ? I.) If we are dealing with values between 0,1 and 0,9 we may use table 3. To solve the first question we select the respective horizontal line for p(obs) and determine which column corresponds to our value of n and find the respective value of p(esp) by interpolating between columns. In order to solve the second problem we start with the respective column for p(esp) and find the horizontal line for the given value of n either diretly or by approximation and by interpolation. 2) For frequencies smaller than 0,1 we have to use table 4 and transform the fractions p(esp) and p(obs) in numbers of Poisson series by multiplication with n. Tn order to solve the first broblem, we verify in which line the lower Poisson limit is equal to m(obs) and transform the corresponding value of m into frequecy p(esp) by dividing through n. The observed frequency may thus be a chance deviate of any value between 0,0... and the values given by dividing the value of m in the table by n. In the second case we transform first the expectation p(esp) into a value of m and procure in the horizontal line, corresponding to m(esp) the extreme values om m which than must be transformed, by dividing through n into values of p(obs). F) Partial and progressive tests may be recomended in all cases where there is lack of material or where the loss of time is less importent than the cost of large scale experiments since in many cases the minimun number necessary to garantee the results within the limits of precision is rather large. One should not forget that the minimun number really represents at the same time a maximun number, necessary only if one takes into consideration essentially the disfavorable variations, but smaller numbers may frequently already satisfactory results. For instance, by definition, we know that a frequecy of p means that we expect one individual in every total o(f1-p). If there were no chance variations, this number (1- p) will be suficient. and if there were favorable variations a smaller number still may yield one individual of the desired type. r.nus trusting to luck, one may start the experiment with numbers, smaller than the minimun calculated according to the formulas given above, and increase the total untill the desired result is obtained and this may well b ebefore the "minimum number" is reached. Some concrete examples of this partial or progressive procedure are given from our genetical experiments with maize.

Taxonomia da subfamília Corinninae (Araneae, Corinnidae) nas regiões neotropical e neártica

The subfamily Corinninae is characterized and diagnosed. Two synapomorphies are hypothesized for the subfamily, both regarding the male palpal reservoir, which is primarily coiled and presents a sclerotized distal sector. Seventeen genera are recognized, six of which are new: Abapeba (type species Corinna lacertosa Simon), Erendira (type species Corinna pallidoguttata Simon), Septentrinna (type species Corinna bicalcarata Simon), Simonestus (type species Diestus validus Simon), Tapixaua (type species T. callida sp. nov.) and Tupirinna (type species T. rosae sp. nov.). The genera Creugas Thorell, Falconina Brignoli and Paradiestus Mello-Leitão are revalidated. Diestus Simon and Lausus Simon are newly synonymized with Corinna C. L. Koch. Chemmis Simon is included in the synonymy of Megalostrata Karsch. Hypsinotus L. Koch is removed from the synonymy of Corinna and included in the synonymy of Creugas. Thirteen new species are described: Septentrinna yucatan and S. potosi from Mexico; Tupirinna rosae from Venezuela and Brazil; Tapixaua callida from Brazil and Peru; Abapeba hoeferi, A. rioclaro, A. taruma, Corinna ducke, C. colombo, C. mourai, C. recurva and Parachemmis manauara from Brazil; Creugas lisei from Brazil, Argentina and Uruguay. Twenty seven species are redescribed. Fifty eight new combinations are presented: from Chemmis, Septentrinna steckleri (Gertsch); from Corinna, Abapeba abalosi (Mello-Leitão), A. cleonei (Petrunkevitch), A. echinus (Simon), A. grassima (Chickering), A. guanicae (Petrunkevitch), A. lacertosa (Simon), A. luctuosa (F. O. Pickard-Cambridge), A. lugubris (Schenkel), A. pennata (Caporiacco), A. kochi (Petrunkevitch), A. saga (F. O. Pickard-Cambridge), A. wheeleri (Petrunkevitch), Creugas annamae (Gertsch & Davis), C. apophysarius (Caporiacco), C. bajulus (Gertsch), C. bellator (L. Koch), C. bicuspis (F.O. Pickard-Cambridge), C. epicureanus (Chamberlin), C. falculus (F. O. Pickard-Cambridge), C. mucronatus (F. O. Pickard-Cambridge), C. navus (F. O. Pickard-Cambridge), C. nigricans (C. L. Koch), C. plumatus (L. Koch), C. praeceps (F. O. Pickard-Cambridge), C. silvaticus (Chickering), C. uncatus (F. O. Pickard-Cambridge), Erendira luteomaculatta (Petrunkevitch), E. pallidoguttata (Simon), E. subsignata (Simon), Falconina albomaculosa (Schmidt), F. crassipalpis (Chickering), F. gracilis (Keyserling), Megalostrata raptrix (L. Koch), Paradiestus egregius (Simon), P. giganteus (Karsch), P. penicillatus (Mello-Leitão), P. vitiosus (Keyserling), Septentrinna bicalcarata (Simon), S. paradoxa (F. O. Pickard-Cambridge), S. retusa (F. O. Pickard-Cambridge), Simonestus pseudobulbolus (Caporiacco), S. robustus (Chickering), S. semiluna (F.O. Pickard-Cambridge), Stethorrhagus maculatus (L. Koch) and Xeropigo smedigari (Caporiacco); from Diestus, Corinna alticeps (Keyserling), C. kochi (Simon), Simonestus occidentalis (Schenkel), S. separatus (Schmidt) and S. validus (Simon); from Lausus, Corinna grandis (Simon) and Abapeba sicarioides (Mello-Leitão); from Medmassa, Corinna andina (Simon) and C. venezuelica (Caporiacco); from Megalostrata, Erendira atrox (Caporiacco) and Erendira pictitorax (Caporiacco); from Parachemmis, Tupirinna trilineata (Chickering). Five combinations are restaured: Corinna aenea Simon, Creugas cinnamius Simon, Creugas gulosus Thorell, Falconina melloi (Schenkel), Paradiestus aurantiacus Mello-Leitão. Twenty five new synonymies are proposed: Diestus altifrons Mello-Leitão with Corinna nitens (Keyserling); Corinna tomentosa Simon, C. tridentina Mello-Leitão, Hypsinotus flavipes Keyserling, H. humilis Keyserling and Xeropigo scutulatus Simon with Xeropigo tridentiger (O. Pickard-Cambridge); Corinna cribosa Mello-Leitão and C. stigmatica Simon with Falconina gracilis (Keyserling); Corinna casueta Chickering with SIMONestus separatus (Schmidt); Corinna abnormis Petrunkevitch, C. antillana BRYANT, C. consobrina Simon, C. inornata Kraus, C. nervosa F. O. Pickard-Cambridge, C. wolleboeki Banks, Creugas cetratus Simon, C. senegalensis Simon and Hypsinotus gracilipes Keyserling with Creugas gulosus Thorell; Chemmis frederici Simon, Delozeugma formidabile O. Pickard-Cambridge, D. mordicans O. Pickard-Cambridge, Megalostrata sperata Kraus and M. venifica KARSCH with Megalostrata raptrix (L. Koch); Megalostrata lohmanderi Caporiacco with Erendira atrox (Caporiacco); Corinna tenubra Chickering with Parachemmis fuscus Chickering. One new name, Creugas berlandi, is erected for Corinna bellatrix Schmidt. Males of Creugas cinnamius, Corinna kochi, Methesis semirufa Simon, Paradiestus aurantiacus, Septentrinna steckleri and Xeropigo smedigari, the females of Paradiestus giganteus, Septentrinna bicalcarata and the adult female of S. steckleri are described for the first time.

Sinopse dos gêneros Scopadus e Omosarotes (Coleoptera, Cerambycidae, Lamiinae)

Descriptions, synonym, new combinations and key to the species of Omosarotes Pascoe, 1860 are given. The male of Scopadus ciliatus Pascoe, 1857 is described. New species described: Omosarotes ater (type locality: Santo Domingo de los Colorados, Ecuador). New synonym proposed: Acanthomerosternoplon Tippmann, 1955 with Omosarotes Pascoe, 1860. New combinations: Omosarotes nigripennis (Zajciw, 1970) (from Scopadus Pascoe, 1857), O. paradoxum (Tippmann, 1955) and O. foxi (Lane, 1973), both from Acanthomerosternoplon Tippmann, 1955.

Notas e descrições em Parandrini (Coleoptera, Cerambycidae, Parandrinae)

The genus Parandra is reviewed and four genera are recognized: Parandra Latreille, 1804, Neandra Lameere, 1912, stat. nov., Archandra Lameere, 1912, stat. nov. and Acutandra gen. nov. The genus Parandra is subdivided in two subgenera: Parandra (Parandra) s. str. and Parandra (Birandra) subgen. nov. The geographical distribution of P. (P.) laevis Latreille, 1804 is commented and the probable synonymy between P. cubaecola Chevrolat, 1862 and P. (P.) cribrata Thomson, 1861 is discussed. New species described: P. (P.) tavakiliani from Puerto Rico and P. (Birandra) mariahelenae from Jamaica. New combinations: Neandra brunnea (Fabricius, 1798), Neandra marginicollis (Schaeffer, 1929), Archandra caspia (Ménétriès, 1832), Acutandra punctatissima (Thomson, 1861), A. degeeri (Thomson, 1867), A. murrayi (Lameere, 1912), A. araucana (Bosq, 1951), A. ubitiara (Santos-Silva & Martins, 2000), all from Parandra. Keys to genera of Parandrini, subgenera of Parandra and American species of Parandra and Acutandra are added.

Catalogue of the type material of Phasmatodea (Insecta) deposited in Brazilian museums

The type material of Phasmatodea deposited in Brazilian museums and institutions is listed for the first time. New synonyms are proposed: Phibalosoma paulense Toledo Piza, 1938, Phibalosoma rochai Toledo Piza, 1938, Bacteria tuberculata Toledo Piza, 1938 and Bacteria tuberculata var. argentina Toledo Piza, 1938 are junior synonyms of Cladomorphus phyllinus (Gray, 1835). Nineteen new combinations are established.

Comentario ao esquema de classificação das Salmonellas de Kauffmann-White

The classification of salmonellae in accordance with the Kauffmann-White schema accepted by the presents various inconveniences and difficulties to application. Among these is the necessity of preparing, dosing and preserving a considerable number of specific sera whose validity as is well known, is limited. The criterion of Kauffmann’s classification is exclusively, for it abandoned cultural tests, leaving therefore only a unilateral criterion. By following it one might include Chromobacterium typhi-flavum in the Salmonella genus as well as other bacteria which differ completely from the Salmonella, as long as they are antigenically related. On the other hand, the chart approximates or separates in the different groups of antigen O species or types of salmonellae which are biologically close or almost indistinguishable. The chart has given rise to an excessive number of species and lypes of salmonellae which from 44 in the chart approved by the in 1934 rose ro 60 in Bergey’s Manual and everything leads one to believe that the end is not yet for every day new lypes or species are found. And perforce this must be so for new antigenic factors have been found which give rise to new structural combinations. Applying the formula of combinations (formule) to the factors already known, there are probable possibilities of having 260 different antigenic combinations in group A, or 3260 lypes or species if all the flagellate antigens of the other groups should be found, in it combined 2 and 2. Futher applying the formula of combinations to the other groups there would be possibility of so many combinations that the number of salmonellae would exceed the number of known bacterian species or perhaps the number of those existing on earth. Undoubledly Kauffmann-White’s chart is an improvement, but the bacterian analysis made with it was exaggerated and exceeded the limit of the present possibilities of the realities of life. It revealed interesting aspects of the somatic complexity of bacteria but seems untenable because of its use in pratical sense.

Clarke critical values of subanalytic Lipschitz continuous functions

We prove that any subanalytic locally Lipschitz function has the Sard property. Such functions are typically nonsmooth and their lack of regularity necessitates the choice of some generalized notion of gradient and of critical point. In our framework these notions are defined in terms of the Clarke and of the convex-stable subdifferentials. The main result of this note asserts that for any subanalytic locally Lipschitz function the set of its Clarke critical values is locally finite. The proof relies on Pawlucki's extension of the Puiseuxlemma. In the last section we give an example of a continuous subanalytic function which is not constant on a segment of "broadly critical" points, that is, points for which we can find arbitrarily short convex combinations of gradients at nearby points.

A study of the endocervical columnar cells I - morphology and frequency

After the observation of many thousands of histological sections of the endocervical mucosa it became evident that its columnar cells present a great variety of aspects not only those of the surface of the canal but also those of the glands. A classification of these cells was made taking into account the staining affinity, the intensity staining of the cytoplasm, the presence or absence of cilia, the shape and location of the nucleus. The various combinations of these different data made possible the characterization of 26 types of cells which we labelled by the alphabetical letters. Two hundred and fifty cervices obtained by cervical amputation and by hysterectomy were studied. The uteri presented lesions in the course of routine laboratory examination. In each of the 250 histological sections there were specifically counted 2,000 columnar cells which cover the cervical canal and 2,000columnar cells which form the glands. A graphic representation of the frequency of both the superficial and glandular columnar cells was presented; this was given the name EPITHELIOGRAM. The variation of the cellular "composition" of each epithelium is discussed and the frequency of the various cellular types after the count of one million of cells is presented.

Desensitization of thermal hyperemia in the skin is reproducible.

OBJECTIVE: Local heating increases skin blood flow SkBF (thermal hyperemia). In a previous study, we reported that a first local thermal stimulus could attenuate the hyperemic response to a second one applied later on the same skin spot, a phenomenon that we termed desensitization. However, other studies found no evidence for desensitization in similar conditions. The aim of the present work was to test whether it was related to differences in instrumentation. METHODS: Twenty-eight healthy young males were studied. Two pairs of heating chambers, one custom-made (our study) and one commercial (other groups), were affixed to forearm skin. SkBF was measured with single-point laser-Doppler flowmetry (LDF) (780nm) in one pair, and laser-Doppler imaging (LDI) (633nm) in the other. A temperature step from 34 to 41°C, was applied for 30minutes and repeated after two hours. RESULTS: During the second thermal challenge, the plateau SkBF was lower than during the first thermal and was observed with each of the four combinations of SkBF measurement techniques and heating equipment (p<0.05 for all conditions, range -9% to -16% of the initial value). CONCLUSION: Desensitization of thermal hyperemia is not specific to peculiar operating conditions.

Sommes-nous prêts à prescrire une polypill à nos patients [Are we ready to prescribe a polypill to our patients?].

The all-in-one pill combination (Polypill) of several active components used in primary prevention of cardiovascular disease was a decade ago purposed to reduce the cardiovascular burden by more than 80%. This Polypill could be approved before 2013 in United States. Although controversed, it could answer to the worried situation even observed in Switzerland: the adherence to secondary prevention treatments is clearly insufficient and the cardiovascular events remain in the first row of death's causes. This abstract summarize the results from interventional studies who tried to valid this concept as well as the main stakes to be assessed on the medical side before to consider such a similar approach in Switzerland.

Using life strategies to explore the vulnerability of ecosystem services to invasion by alien plants

Invasive plants can have different effects of ecosystem functioning and on the provision of ecosystem services, from strongly deleterious impacts to positive effects. The nature and intensity of such effects will depend on the service and ecosystem being considered, but also on features of life strategies of invaders that influence their invasiveness as well as their influence of key processes of receiving ecosystems. To address the combined effect of these various factors we developed a robust and efficient methodological framework that allows to identify areas of possible conflict between ecosystem services and alien invasive plants, considering interactions between landscape invasibility and species invasiveness. Our framework combines the statistical robustness of multi-model inference, efficient techniques to map ecosystem services, and life strategies as a functional link between invasion, functional changes and potential provision of services by invaded ecosystems. The framework was applied to a test region in Portugal, for which we could successfully predict the current patterns of plant invasion, of ecosystem service provision, and finally of probable conflict (expressing concern for negative impacts, and value for positive impacts on services) between alien species richness (total and per plant life strategy) and the potential provision of selected services. Potential conflicts were identified for all combinations of plant strategy and ecosystem service, with an emphasis for those concerning conflicts with carbon sequestration, water regulation and wood production. Lower levels of conflict were obtained between invasive plant strategies and the habitat for biodiversity supporting service. The added value of the proposed framework in the context of landscape management and planning is discussed in perspective of anticipation of conflicts, mitigation of negative impacts, and potentiation of positive effects of plant invasions on ecosystems and their services.

Extra-osseous involvement of Langerhans' cell histiocytosis in children.

The predominant clinical and radiological features of Langerhans' cell histiocytosis (LCH) in children are due to osseous involvement. Extra-osseous disease is far less common, occurring in association with bone disease or in isolation; nearly all anatomical sites may be affected and in very various combinations. The following article is based on a multicentre review of 31 children with extra-osseous LCH. The objective is to summarise the diverse possibilities of organ involvement. The radiological manifestations using different imaging modalities are rarely pathognomonic on their own. Nevertheless, familiarity with the imaging findings, especially in children with systemic disease, may be essential for early diagnosis.

An atlas of human gene expression from massively parallel signature sequencing (MPSS).

We have used massively parallel signature sequencing (MPSS) to sample the transcriptomes of 32 normal human tissues to an unprecedented depth, thus documenting the patterns of expression of almost 20,000 genes with high sensitivity and specificity. The data confirm the widely held belief that differences in gene expression between cell and tissue types are largely determined by transcripts derived from a limited number of tissue-specific genes, rather than by combinations of more promiscuously expressed genes. Expression of a little more than half of all known human genes seems to account for both the common requirements and the specific functions of the tissues sampled. A classification of tissues based on patterns of gene expression largely reproduces classifications based on anatomical and biochemical properties. The unbiased sampling of the human transcriptome achieved by MPSS supports the idea that most human genes have been mapped, if not functionally characterized. This data set should prove useful for the identification of tissue-specific genes, for the study of global changes induced by pathological conditions, and for the definition of a minimal set of genes necessary for basic cell maintenance. The data are available on the Web at http://mpss.licr.org and http://sgb.lynxgen.com.

Single-cell gene-expression profiling reveals qualitatively distinct CD8 T cells elicited by different gene-based vaccines.

CD8 T cells play a key role in mediating protective immunity against selected pathogens after vaccination. Understanding the mechanism of this protection is dependent upon definition of the heterogeneity and complexity of cellular immune responses generated by different vaccines. Here, we identify previously unrecognized subsets of CD8 T cells based upon analysis of gene-expression patterns within single cells and show that they are differentially induced by different vaccines. Three prime-boost vector combinations encoding HIV Env stimulated antigen-specific CD8 T-cell populations of similar magnitude, phenotype, and functionality. Remarkably, however, analysis of single-cell gene-expression profiles enabled discrimination of a majority of central memory (CM) and effector memory (EM) CD8 T cells elicited by the three vaccines. Subsets of T cells could be defined based on their expression of Eomes, Cxcr3, and Ccr7, or Klrk1, Klrg1, and Ccr5 in CM and EM cells, respectively. Of CM cells elicited by DNA prime-recombinant adenoviral (rAd) boost vectors, 67% were Eomes(-) Ccr7(+) Cxcr3(-), in contrast to only 7% and 2% stimulated by rAd5-rAd5 or rAd-LCMV, respectively. Of EM cells elicited by DNA-rAd, 74% were Klrk1(-) Klrg1(-)Ccr5(-) compared with only 26% and 20% for rAd5-rAd5 or rAd5-LCMV. Definition by single-cell gene profiling of specific CM and EM CD8 T-cell subsets that are differentially induced by different gene-based vaccines will facilitate the design and evaluation of vaccines, as well as enable our understanding of mechanisms of protective immunity.

Molecular variation at a candidate gene implicated in the regulation of fire ant social behavior

The fire ant Solenopsis invicta and its close relatives display an important social polymorphism involving differences in colony queen number. Colonies are headed by either a single reproductive queen (monogyne form) or multiple queens (polygyne form). This variation in social organization is associated with variation at the gene Gp-9, with monogyne colonies harboring only B-like allelic variants and polygyne colonies always containing b-like variants as well. We describe naturally occurring variation at Gp-9 in fire ants based on 185 full-length sequences, 136 of which were obtained from S. invicta collected over much of its native range. While there is little overall differentiation between most of the numerous alleles observed, a surprising amount is found in the coding regions of the gene, with such substitutions usually causing amino acid replacements. This elevated coding-region variation may result from a lack of negative selection acting to constrain amino acid replacements over much of the protein, different mutation rates or biases in coding and non-coding sequences, negative selection acting with greater strength on non-coding than coding regions, and/or positive selection acting on the protein. Formal selection analyses provide evidence that the latter force played an important role in the basal b-like lineages coincident with the emergence of polygyny. While our data set reveals considerable paraphyly and polyphyly of S. invicta sequences with respect to those of other fire ant species, the b-like alleles of the socially polymorphic species are monophyletic. An expanded analysis of colonies containing alleles of this clade confirmed the invariant link between their presence and expression of polygyny. Finally, our discovery of several unique alleles bearing various combinations of b-like and B-like codons allows us to conclude that no single b-like residue is completely predictive of polygyne behavior and, thus, potentially causally involved in its expression. Rather, all three typical b-like residues appear to be necessary.