Populations ofP Research Articles

Diversity of root-lesion nematodes (Pratylenchus spp.) associated with wheat (Triticum aestivum and T. durum) in Morocco

Root-lesion nematodes (Pratylenchus) have a worldwide distribution and cause severe production constraints on numerous important crops. During a survey of the wheat-growing area of Morocco, 17 populations of root-lesion nematode were collected. They were identified on the basis of their morphological and morphometric characters, and by molecular methods. Microscopic observations of females and males demonstrated the occurrence ofP. penetransin 13 of the 17 samples;P. thorneiandP. pseudocoffeaewere detected in four samples from Zaers and a single sample from Settat, respectively. A duplex PCR primer set was used to confirm the presence ofP. penetranswhile the species-specific forward primer PTHO and the common reverse primer D3B were used forP. thornei. For the remaining populations, the D2-D3 expansion segments of the 28S rRNA gene were amplified and the obtained sequences were compared with those ofPratylenchusspecies in the GenBank database. This comparison confirmed the morphological identifications and revealed a population ofP. pinguicaudatus. The study of the phylogenetic relationship of the MoroccanPratylenchuspopulations showed a high similarity (99-100%) between allP. penetranspopulations. The population dynamics of sixPratylenchuspopulations from Morocco were evaluated on carrot disk cultures at 4, 8 and 12 weeks after inoculation, and at 10, 15, 20 and 25°C. The optimum temperature for reproduction of all populations was 20°C. After 8 weeks at this temperature, nematode numbers increased up to 458-fold, 310-fold and 252-fold for the four populations ofP. penetrans, theP. thorneiand theP. pseudocoffeaepopulation, respectively.

Characterisation of amphimictic and parthenogenetic populations of Pratylenchus bolivianus Corbett, 1983 (Nematoda: Pratylenchidae) and their phylogenetic relationships with closely related species

Amphimictic populations of root-lesion nematodes with numerous males and females having three lip annuli, a functional spermatheca and non-areolated lateral field occur on sword fern (Nephrolepis exaltata) in Florida. Identified for decades asPratylenchus penetrans, they appeared to be a morphologically separated species on the basis of a longer stylet (17.8-18.3 μm) thanP. penetrans(15-17 μm) and different lip pattern inen faceview (rectangularvsdumb-bell inP. penetrans). Morphologically similar amphimictic root-lesion nematodes have also been detected on flax lily in Costa Rica. Subsequent morphological observations indicated that these amphimictic root-lesion nematodes from fern and flax lily are closely related to the parthenogenetic speciesP. bolivianus, which has areolated lateral fields. In spite of the reproductive and morphological dissimilarities between these populations, their separation into different species was not supported by the results of molecular analyses of their DNA sequences. The populations used in these analyses included those that are amphimictic from Florida and Costa Rica and others that are parthenogenetic from the type locality in Bolivia, and geographically distant localities in Chile, China, Colombia and Europe. Phylogenetic analyses of the ITS and D2-D3 expansion segments of the 28S rRNA gene indicated that they belong to the same species,P. bolivianus, which consists of two morphotypes,P. bolivianus(am) amphimictic andP. bolivianus(pm) parthenogenetic, herein described and illustrated. Contradictory results were obtained by the analyses using a portion of thehsp90gene. The phylogenetic study, which included sequences of other root-lesion nematodes, a topotype and geographical distant populations ofP. zeae, revealed thatP. bolivianusandP. zeaeformed highly supported clades in the majority consensus trees. PCR with species-specific primers for rapid diagnostics ofP. bolivianusandP. zeaewere developed and tested.

How climate change can affect the distribution range and conservation status of an endemic bird from the highlands of eastern Brazil: the case of the Gray-backed Tachuri, Polystictus superciliaris (Aves, Tyrannidae)

The Gray-backed Tachuri (Polystictus superciliaris) is a Tyrannidae restricted to eastern Brazilian highlands. Its population and range are still thought to be declining mainly due to habitat loss, caused by land use. We evaluated the impacts on its range (increase or decrease, displacement in latitude and altitude), considering possible effects caused by inappropriate land use and climatic changes. For this purpose, we modeled its current range and estimated its overlap between the predicted area and future scenarios. We also analyzed the efficiency of the Brazilian reserves to the species’ protection. The range established by the Maxent model was 76.1% lower than that available in the literature and presented a decrease in the future. Range contraction for the periods under consideration ranged from 22.5% to 77.3%. The distribution center shifts to the southwest (from 102.5 km to 275.4 km) and to higher elevations (1,102 m to 1,428 m). From the predicted range, 20% are under some kind of human occupation. The Brazilian reserves partially protect the species, with only 12% of its range, from the 44.2% expected. Based on these predictions, and depending on the species’ dispersal ability and adaptation, it may become vulnerable in the period of 2080. This study demonstrates that the most important areas for maintaining populations ofP. superciliaris now and in the future are those located in the ‘Iron Quadrangle’, especially the Serra da Gandarela, where it was partially protected by the recently decreed Gandarela National Park. This region should receive special attention because it is strongly threatened by iron mining in areas relevant for conservation located outside this reserve.

Molecular analysis ofPhytophthoradiversity in nursery‐grown ornamental and fruit plants

The genetic diversity ofPhytophthoraspp. was investigated in potted ornamental and fruit tree species. A metabarcoding approach was used, based on a semi‐nestedPCRwithPhytophthoragenus‐specific primers targeting theITS1 region of therDNA. More than 50ITS1 sequence types representing at least 15 distinctPhytophthorataxa were detected. Nine hadITSsequences that grouped them in defined taxonomic groups (P. nicotianae,P. citrophthora,P. meadii,P. taxonPgchlamydo,P. cinnamomi,P. parvispora,P. cambivora,P. niederhauseriiandP. lateralis) whereas three phylotypes were associated to two or more taxa (P. citricolataxon E orIII;P. pseudosyringae,P. ilicisorP. nemorosa; andP. cryptogea,P. erythroseptica,P. himalayensisorP. sp. ‘kelmania’) that can be challenging to resolve withITS1 sequences alone. Three additional phylotypes were considered as representatives of novelPhytophthorataxa and defined asP. meadii‐like,P. cinnamomi‐like andP. niederhauserii‐like. Furthermore, the analyses highlighted a very complex assemblage ofPhytophthorataxa in ornamental nurseries within a limited geographic area and provided some indications of structure amongst populations ofP. nicotianae(the most prevalent taxon) and other taxa. Data revealed new host–pathogen combinations, evidence of new species previously unreported in Italy (P. lateralis) or Europe (P. meadii) and phylotypes representative of species that remain to be taxonomically defined. Furthermore, the results reinforced the primary role of plant nurseries in favouring the introduction, dissemination and evolution ofPhytophthoraspecies.

Comparative genomics of the mimicry switch in Papilio dardanus.

The African Mocker Swallowtail, Papilio dardanus, is a textbook example in evolutionary genetics. Classical breeding experiments have shown that wing pattern variation in this polymorphic Batesian mimic is determined by the polyallelic H locus that controls a set of distinct mimetic phenotypes. Using bacterial artificial chromosome (BAC) sequencing, recombination analyses and comparative genomics, we show that H co-segregates with an interval of less than 500 kb that is collinear with two other Lepidoptera genomes and contains 24 genes, including the transcription factor genes engrailed (en) and invected (inv). H is located in a region of conserved gene order, which argues against any role for genomic translocations in the evolution of a hypothesized multi-gene mimicry locus. Natural populations of P. dardanus show significant associations of specific morphs with single nucleotide polymorphisms (SNPs), centred on en. In addition, SNP variation in the H region reveals evidence of non-neutral molecular evolution in the en gene alone. We find evidence for a duplication potentially driving physical constraints on recombination in the lamborni morph. Absence of perfect linkage disequilibrium between different genes in the other morphs suggests that H is limited to nucleotide positions in the regulatory and coding regions of en. Our results therefore support the hypothesis that a single gene underlies wing pattern variation in P. dardanus.

English

A survey of plantain farms was conducted in April 2012 at four locations in two districts of Ghana. The purpose was to identify plant parasitic nematodes (PPN) associated with plantain production in Ghana. The locations were Adomakokrom and Kenyasi in the Brong Ahafo, Adanwomase and Mpobi in the Ashanti region. Demographic and sociological data of farmers, plantain root lesion scores, PPN populations per 200 cm3 soil and 5 g plantain roots were analyzed. Nematode damage to root at Adomakokrom, Adanwomase, Mpobi and Kenyasi were 50, 75, 75 and 50%, respectively. Five nematode species were recovered from the rhizosphere of plantain. The nematodes were in the order of importance; Pratylenchus coffeae, Meloidogyne spp.,Rotylenchulus reniformis, Radopholus similis and Helicotylenchus multicintus. High populations ofP. coffeae (803/200 cm3), H. multicintus (292/200 cm3) and R. reniformis (343/200 cm3) were extracted from soil samples at Adomakokrom, Adanwomase and Adanwomase respectively. Four parasitic nematodes; Meloidogyne spp., P. coffeae, R. reniformis and R. similis were extracted from plantain roots. Root populations were higher compared with soil samples. For sustainable plantain production in Ghana, an efficient management option must be devised.   Key words: Ghana, integrated pest management, Musa spp., plant parasitic nematodes.

Genetic and epigenetic variation in a cosmopolitan grass Poa annua from Antarctic and Polish populations

Genetic and epigenetic variation in a cosmopolitan grassPoa annuafrom Antarctic and Polish populationsPoa annuaL. is the only non-native vascular plant that was successfully established in the maritime Antarctic. This project aimed to determine the amount of genetic and epigenetic variation within and between two populations ofP. annua, one from South Shetland Is. (Antarctic) and the other one from Central Europe. We applied two AFLP marker systems, using endonucleases that recognised the same restriction site but differed in their sensitivity towards methylation. The Antarctic population differed from the Polish one both at the genetic and epigenetic levels. Genetic variability in the Antarctic population was lower than in the Polish one. Some loci in the Antarctic population showed signs of selection. The difference between Polish and Antarctic populations might be due to a weak bottleneck effect followed by population expansion. Using only epigenetic markers, the Antarctic population exhibited increased variation level compared to the Polish one. These may have resulted from plastic responses to environmental factors and could be associated with survival in extreme conditions.

Foraging Activity and Trophic Spectrum of Red AntPogonomyrmex barbatusSmith, 1858, in Productivity-Contrasted Microenvironments

Foraging strategies can be influenced by many factors such as abundance, availability, and toxicity of the resources. In arid zones, the distribution and productivity of plants also act as additional factors that affect foraging strategies. Twenty colonies ofPogonomyrmex barbatusants were studied in an arid zone of central Mexico to evaluate the trophic niche breadth in two sites with contrasting productivities in terms of their diversity and amount of resources during two seasons. The results suggest that when the resources are abundant as in the rainy season, the trophic niche breadth is reduced in sites with high productivity and, in the same sites, the trophic niche breadth increases when the resources are limited as in the dry season. In contrast, the trophic niche breadth is similar in both conditions of resource availability (i.e., rainy and dry seasons) at sites with low productivity. During the dry season, populations ofP. barbatusshowed a similar foraging behavior in sites with high and low productivity. Thus, the particular characteristics of a site can significantly affect the foraging strategies of the ants in those environments.

Origin and genetic diversity of an introduced wall lizard population and its cryptic congener

The Common Wall Lizard (Podarcis muralis) has been introduced within large parts of Central Europe, the UK and parts of North America. In an introduced population of this species in Lower Saxony, Germany, we found in addition to mtDNA haplotypes ofP. muralisalso haplotypes of its congenerPodarcis liolepis, a species that hitherto has never been recorded outside its native range. We therefore, (1) wanted to identify the geographic origin of the founder individuals of both non-native populations, (2) test for hybridization between introduced individuals of both species in Germany and (3) compare levels of genetic diversity between native and introduced populations. We sequenced a fragment of the mitochondrial cytochromebgene and genotyped individuals of the introduced as well as native populations of both species at eleven microsatellite loci. Our results suggest that the founders presumably stem from a region in the eastern Pyrenees, where sympatric populations ofP. muralisandP. liolepisare known. No evidence for gene flow between the two species was found in the introduced population. These results are consistent with behavioural observations indicating agonistic interactions ofP. muralistowardsP. liolepisrather than cross-species attraction. Compared to the native populations, high levels of genetic diversity have been retained in the introduced population of both species and no evidence for a genetic bottleneck was found. The effective population size was high inP. muralis, but substantially smaller inP. liolepis.

Reproductive Ecology of Male and Female Strobili and Mating System in Two Different Populations ofPinus roxburghii

We studied several flowering traits, namely, male-female cone phenology, male-female cone production per tree, mating system, sex ratio, air-borne pollen grains and pollen migration, over four successive years in two different natural populations of P. roxburghii from Garhwal Himalaya, India. Assessment of each trait mentioned except pollen dispersion was done by selecting five representative trees randomly in each population. The pollen migration was studied on naturally isolated source trees. The pollen trapping was done in all directions up to 2.5 km. The average reproductive period in P. roxburghii was 36 days with 3–5 days protandry. There were significant year and population effects for male and female cone output and pollen grains production per tree. In mass production year (1999), an average production of pollen cone per tree was estimated as 42.44 ± 8.32 × 103 at lower altitude and 28.1 ± 0.89 × 103 at higher altitude. The controlled pollination results in high level of outcrossing with 90% seed setting. We conclude that the high male-female ratio and tremendous pollen production capacity in P. roxburghii indicate high male competition among trees within populations. The isolation strip of 600 m is considered minimal for the management of seed orchard.

Multiple independent introductions of Plasmodium falciparum in South America.

The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence--archeological and genetic--suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade.

Genetic population structure of the paper waspPolistes olivaceus(Hymenoptera: Vespidae) in Bangladesh

AbstractDispersal triggers gene flow, which in turn strongly affects the ensuing genetic population structure of a species. Using nuclear microsatellite loci and mitochondrial DNA (mtDNA), we estimated the genetic population structure of the waspPolistes olivaceusthroughout Bangladesh. The level of population differentiation using nuclear markers (FST) appeared to be much lower than that estimated using mtDNA haplotype sequences (ФST), even after correcting for effective population size differences between the two markers. These results suggest a philopatric tendency, in which gynes disperse less than males. We observed no isolation by distance among the study populations at either the nuclear or mtDNA level, suggesting nonequilibrium between gene flow and drift as a result of very frequent interpopulation movement. For the nuclear markers, an individual assignment test showed no genetically and geographically distinct groups. Instead, phylogenetic analyses as well as a minimum spanning network using mtDNA haplotypes consistently revealed two distinct lineages. The distribution of haplotypes indicated western populations with a single lineage and offered clear evidence for restricted gene flow across the Jamuna–Padma–Upper Meghna river system. Mismatch distributions exhibited a unimodal distribution, which along with a starlike haplotype network, suggested a population expansion in lineage I but not in lineage II. Overall, these results suggest that gene flow among populations ofP. olivaceuswas affected by both female philopatry and a major river system across Bangladesh.

Genetic characterization indicates that a specific subpopulation of Pseudomonas aeruginosa is associated with keratitis infections.

Pseudomonas aeruginosa is a common opportunistic bacterial pathogen that causes a variety of infections in humans. Populations of P. aeruginosa are dominated by common clones that can be isolated from diverse clinical and environmental sources. To determine whether specific clones are associated with corneal infection, we used a portable genotyping microarray system to analyze a set of 63 P. aeruginosa isolates from patients with corneal ulcers (keratitis). We then used population analysis to compare the keratitis isolates to a wider collection of P. aeruginosa from various nonocular sources. We identified various markers in a subpopulation of P. aeruginosa associated with keratitis that were in strong disequilibrium with the wider P. aeruginosa population, including oriC, exoU, katN, unmodified flagellin, and the carriage of common genomic islands. The genome sequencing of a keratitis isolate (39016; representing the dominant serotype O11), which was associated with a prolonged clinical healing time, revealed several genomic islands and prophages within the accessory genome. The PCR amplification screening of all 63 keratitis isolates, however, provided little evidence for the shared carriage of specific prophages or genomic islands between serotypes. P. aeruginosa twitching motility, due to type IV pili, is implicated in corneal virulence. We demonstrated that 46% of the O11 keratitis isolates, including 39016, carry a distinctive pilA, encoding the pilin of type IV pili. Thus, the keratitis isolates were associated with specific characteristics, indicating that a subpopulation of P. aeruginosa is adapted to cause corneal infection.

African great apes are natural hosts of multiple related malaria species, including Plasmodium falciparum

Plasmodium reichenowi, a chimpanzee parasite, was until very recently the only known close relative of Plasmodium falciparum, the most virulent agent of human malaria. Recently, Plasmodium gaboni, another closely related chimpanzee parasite, was discovered, suggesting that the diversity of Plasmodium circulating in great apes in Africa might have been underestimated. It was also recently shown that P. reichenowi is a geographically widespread and genetically diverse chimpanzee parasite and that the world diversity of P. falciparum is fully included within the much broader genetic diversity of P. reichenowi. The evidence indicates that all extant populations of P. falciparum originated from P. reichenowi, likely by a single transfer from chimpanzees. In this work, we have studied the diversity of Plasmodium species infecting chimpanzees and gorillas in Central Africa (Cameroon and Gabon) from both wild-living and captive animals. The studies in wild apes used noninvasive sampling methods. We confirm the presence of P. reichenowi and P. gaboni in wild chimpanzees. Moreover, our results reveal the existence of an unexpected genetic diversity of Plasmodium lineages circulating in gorillas. We show that gorillas are naturally infected by two related lineages of parasites that have not been described previously, herein referred to as Plasmodium GorA and P. GorB, but also by P. falciparum, a species previously considered as strictly human specific. The continuously increasing contacts between humans and primate populations raise concerns about further reciprocal host transfers of these pathogens.

Analysis of genetic structure of white croaker using amplified fragment length polymorphism (AFLP) markers

The genetic structure of 4 populations of white croaker Pennahia argentata was analyzed by amplified fragment length polymorphism (AFLP) technology. A total of 304 putative loci were detected by the 5 primer combinations, of which 200 were polymorphic. The proportion of polymorphic loci among four populations varied from 47.13 to 57.63%. The population with the highest Nei’s genetic diversity and Shannon diversity index was Ariake Sea population, the lowest Nei’s genetic diversity and Shannon diversity index was found in Ise Bay population. Two geographic clades (Chinese clade and Japanese clade) were detected among 70 individuals of white croaker by AFLP markers; molecular variance analysis and pairwise FST also supported the separation of Chinese and Japanese populations ofP. argentata. The Pleistocene isolation and biological characteristics of species may be responsible for the genetic differentiation of P. argentata between China and Japan coastal waters. Our result also revealed that white croaker might choose the retention larval strategy within coastal waters to minimize the offshore dispersal. Key words: White croaker, Pennahia argentata, amplified fragment length polymorphism (AFLP), genetic structure.

Variation in the chloroplast DNA of Swiss stone pine (Pinus cembraL.) reflects contrasting post‐glacial history of populations from the Carpathians and the Alps

AbstractAim To characterize the genetic structure and diversity ofPinus cembraL. populations native to two disjunct geographical areas, the Alps and the Carpathians, and to evaluate the rate of genetic differentiation among populations.Location The Swiss Alps and the Carpathians.Methods We screened 28 populations at three paternally inherited chloroplast simple sequence repeats (cpSSRs) for length variation in their mononucleotide repeats. Statistical analysis assessed haplotypic variation and fixation indices. Hierarchical analysis of molecular variance (AMOVA), Mantel test, spatial analysis of molecular variance (SAMOVA) andbarrieranalyses were applied to evaluate the geographical partitioning of genetic diversity across the species’ range.Results Haplotypic diversity was generally high throughout the natural range ofP. cembra, with the mean value substantially higher in the Carpathians (H = 0.53) than in the Alps (H = 0.35). The isolated Carpathian populations showed the highest haplotype diversity among the populations originating from the High Tatras (Velka Studena Dolina) and South Carpathians (Retezat Mountains). AMOVA revealed that only 3% of the total genetic variation derived from genetic differentiation between the two mountain ranges. Differentiation among Carpathian populations was higher (FST = 0.19) than among Alpine populations (FST = 0.04). Low, but significant, correlation was found between the geographical and genetic distances among pairs of populations (r = 0.286,P < 0.001). SAMOVA results revealed no evident geographical structure of populations.barrieranalysis showed the strongest differentiation in the eastern part of the species’ range, i.e. in the Carpathians.Main conclusions The populations ofP. cembrawithin the two parts of the species’ range still share many cpDNA haplotypes, suggesting a common gene pool conserved from a previously large, continuous distribution range. Carpathian populations have maintained high haplotypic variation, even higher than Alpine populations, despite their small population sizes and spatial isolation. Based on our results, we emphasize the importance of the Carpathian populations of Swiss stone pine for conservation. These populations comprise private haplotypes and they may represent a particular legacy of the species’ evolutionary history.

Natural variation in Pristionchus pacificus insect pheromone attraction involves the protein kinase EGL-4

The geographical mosaic theory of coevolution predicts that different local species interactions will shape population traits, but little is known about the molecular factors involved in mediating the specificity of these interactions. Pristionchus nematodes associate with different scarab beetles around the world, with Pristionchus pacificus isolated primarily from the oriental beetle in Japan. In particular, the constituent populations of P. pacificus represent a rare opportunity to study multiple specialized interactions and the mechanisms that influence population traits at the genetic level. We identified a component of the cGMP signaling pathway to be involved in the natural variation for sensing the insect pheromone ETDA, using targeted introgression lines, exogenous cGMP treatment, and a null egl-4 allele. Our data strongly implicate egl-4 as one of several loci involved in behavioral variation in P. pacificus populations. That EGL-4 homologs have been independently implicated for behavioral variations in other invertebrate models suggests that EGL-4 may act as a modulator for interspecies behavioral repertoires across large phylogenetic distances.

On status badges and quality signals in the paper waspPolistes dominulus: body size, facial colour patterns and hierarchical rank

To establish a dominance order, social animals often rely on indicators of fighting to avoid costly aggressive encounters. In some species, individuals use colour patterns to signal their social status. Recent studies claimed that facial markings in the eusocial paper wasp Polistes dominulus are status badges that allow co-foundresses to form a linear hierarchy based on individual quality. Here, we evaluated facial patterns in natural populations of P. dominulus, in its native range, to observe whether the marks reflect overall wasp quality in different contexts. We used the same measures of clypeus patterns used by earlier studies, but did not find that they functioned as status badges. Our analyses showed no evidence that visual markers are related to: (i) size, (ii) probability of surviving winter, (iii) social rank in spring associations, or (iv) health status (assessed by the presence of strepsipteran endoparasites). Size, however, is important. Larger wasps are more likely to survive the winter and to acquire the dominant position in spring associations. Larvae infected with endoparasites become smaller adult wasps. These findings suggest that body size is a reliable quality indicator on which wasps build their social networks, and that clypeus patterning is not involved.

Allozyme differentiation among populations of Pinus sylvestris (L.) from Sweden and China

Allozyme differentiation at 14 loci was studied among 7 populations of Pinus sylvestris rapresenting one geographic vaniety lapponica from Sweden and two vaneties. mongolica and sylvestriformis from China. The expected and observed heterozygosities were high and ranged between 0.165 and 0.282. and between 0.164 and 0.278 respectively, With the exception of the var sylvestriformis, the patterns of genetic variation among populations were in accordance with the patterns of their geographic distribution. Nei's genetic diversity statistics showed that 7.5 % of the total diversity was due to differences among varieties. Pronounced differences were found between the var sylvestriformis population and the populations representing the other two varieties. On the other hand, less differentiation was found between the geographically very distant var. lapponica and var. mongolica. It appears that as a result of past events the patterns of differentiation among populations ofP. sylveslris are more complex than previously thought, It is possible that the individual geographic vanietes of this species have a different evolutionary history.

Genetic and Immunological Comparison of the Cladoceran Parasite Pasteuria ramosa with the Nematode Parasite Pasteuria penetrans

Pasteuria penetrans, an obligate endospore-forming parasite of Meloidogyne spp. (root knot nematodes), has been identified as a promising agent for biocontrol of these destructive agricultural crop pests. Pasteuria ramosa, an obligate parasite of water fleas (Daphnia spp.), has been shown to modulate cladoceran populations in natural ecosystems. Selected sporulation genes and an epitope associated with the spore envelope of these related species were compared. The sigE and spoIIAA/spoIIAB genes differentiate the two species to a greater extent than 16S rRNA and may serve as probes to differentiate the species. Single-nucleotide variations were observed in several conserved genes of five distinct populations of P. ramosa, and while most of these variations are silent single-nucleotide polymorphisms, a few result in conservative amino acid substitutions. A monoclonal antibody directed against an adhesin epitope present on P. penetrans P20 endospores, previously determined to be specific for Pasteuria spp. associated with several phytopathogenic nematodes, also detects an epitope associated with P. ramosa endospores. Immunoblotting provided patterns that differentiate P. ramosa from other Pasteuria spp. This monoclonal antibody thus provides a probe with which to detect and discriminate endospores of different Pasteuria spp. The presence of a shared adhesin epitope in two species with such ecologically distant hosts suggests that there is an ancient and ecologically significant recognition process in these endospore-forming bacilli that contributes to the virulence of both species in their respective hosts.