Multiple Molecular Forms of Acetylcholinesterase in the Nematode Caenorhabditis elegans

Abstract: Extracts of the nematode Caenorhabditis elegans contain five molecular forms of acetylcholinesterase (AChE) activity that can be separated by a combination of selective solubilization, velocity sedimentation, and ion-exchange chromatography. These are called form IA (5.2s), form IB (4.9.s), form II (6.7s), form III (11.3s), and form IV (13.0s). All except form III are present in significant amounts in rapidly prepared extracts and are probably native; form III is probably derived autolytically from form IV. Most of forms IA and IB can be solubilized by repeated extractions without detergent, whereas forms II, III, and IV require detergent for effective solubilization and may therefore be membrane-bound. High salt concentrations are not required for, and do not aid in, the solubilization of these forms. For all forms, molecular weights and frictional ratios have been estimated by a combination of gel permeation chromatography and velocity sedimentations in both H₂O and D₂O. The molecular weight estimates range from 83,000 to 357,000 and only form II shows extensive asymmetry. The separated forms have been characterized with respect to substrate affinity, substrate specificity, inhibitor sensitivity, thermal inactivation, and detergent sensitivity. Judging by these properties, C. elegans is like other invertebrates in that none of its cholinesterase forms resembles either the “true” or the “pseudo” cholinesterase of vertebrates. However, internal comparison of the C. elegans forms clearly distinguishes forms IA, III, and IV as a group from forms IB and II; the former are therefore designated “class A” forms, the latter “class B” forms. Genetic evidence indicates that separate genes control class A and class B forms, and that these two classes overlap functionally. Several factors, including kinetic properties, molecular asymmetry, molecular size, and solubility, all suggest that a molecular model of the multiple cholinesterase forms observed in vertebrate electric organs probably does not apply in C. elegans. Potential functional roles and subunit structures of the multiple AChE forms within each C. elegans class are discussed.     

Study of two forms of the adult Stenocranus minutus

• 1 In studies on Stenocranus minutus, two winged forms of adults have been observed, macropterous and sub-macropterous. Macropterous individuals, with extra-long wings, have not been previously observed or described. Probably only the macropterous form disperses by flight.
• 2 The two forms differ in their wing lengths, intensity and extent of pigmentation.
• 3 The rate of maturation differs in the two forms. In macropters, maturation is delayed; the period of oviposition is shorter and they are less fecund.
• 4 Macropters do not live as long as sub-macropters.
• 5 The macropters weigh less than the sub-macropters.
• 6 Under laboratory conditions, both forms can hop but the macropterous forms fly for a longer time than the sub-macropters.
• 7 At 25°C, more macropterous forms were produced on wilting Dactylis than on green, succulent Dactylis.
• 8 Dispersal of field population was inferred from changes in proportions of the two forms and by simultaneous occurrence of macropters in aerial suction traps.
• 9 The macropterous forms of S.minutus migrate a few weeks after emergence while still immature and migration coincides with drying up of host plant, Dactylis glomerata L.
• 10 Relatively high temperature, low wind speeds and a small number of hours of sunlight seem to favour dispersal by flight in S.minutus.

     

Hybridization of two forms of ninespine stickleback,Pungitius pungitius and P. platygaster,under experimental conditions and an attempt to predict the consequences of their contact in nature

Synopsis In aquaria and in ponds crosses were made between two closely related allopatric forms of ninespine stickleback of the genus Pungitius (P. pungitius and P. platygaster). There were no ethological isolation mechanisms; F₁, F₂ and F₃ hybrids are fertile; experimental hybrid stocks as well as backcrosses maintain themselves for at least three generations. F₁ hybrids are readily distinguishable from parental forms by a combination of morphological characters; F₂ hybrids grown in the north near the Arctic circle, are morphologically similar to P. pungitius. The southern form P. platygaster does not survive in northern conditions; eggs of the northern form P. pungitius die at a temperature of 28°C, normal for the spawning of the southern form. By 9 out of 19 studied morphological characters there are distinctions between the two forms. Therefore, ecologically and morphologically the two forms have diverged rather significantly. On the other hand, ethologically and genetically (as judged by the absence of postmating isolating mechanisms) the forms have diverged only slightly. As a result, the differences between the two forms are considered not to exceed the subspecies or at least semispecies rank.In recent years, due to a disturbance of the ranges of both these forms in Eurasia, a tendency for a secondary contact between P. pungitius and P. platygaster appeared in the basins of the rivers Volga and Irtysh. In the immediate future the two forms are expected to come into contact. From our data we predict possible introgressive hybridization between the northern and sourthern forms in natural conditions.     

Phylogenetic and biogeographic analysis of the spear lobsters Linuparus (Decapoda: Palinuridae), with the description of a new species

Linuparus White, 1847 comprises three extant species, Linuparus trigonus (Von Siebold, 1824), L. sordidusBruce, 1965, and L. somniosusBerry and George, 1972, as well as 32 fossil species. Most fossil records are from North America and Europe, but the extant species are all confined to the Indo-West Pacific. Different colour forms in L. trigonus and L. sordidus have been noted, with Northern Hemisphere specimens generally darker in colour for both species. The phylogenetic relationships of the extant Linuparus species, including the colour forms, were investigated using mitochondrial 12S rRNA and COI gene sequence analysis. We found no genetic evidence to differentiate the colour morphs of L. sordidus, but the two colour forms of L. trigonus were clearly distinct at the species level. This is supported morphologically by a consistent difference in the shape of the thoracic sternum between the two forms. The paler coloured Southern Hemisphere form is described as a new species, L. meridionalis. Phylogenetic analysis shows that L. trigonus and L. meridionalis sp. nov. are derived sister taxa, while L. somniosus is basal within the genus. Thus the present results support the previous hypothesis that Linuparus was originated in shallow water.     

Systematic significance of tridentate pedicellariae in the echinoid genera Diadema and Echinothrix

Abstract. The tridentate pedicellariae in all species of Diadema and Echinothrix recognized by Mortensen, plus species described later (to include D. palmeri and two color morphs of E. calamaris) were examined to identify diagnostic species characters, and to determine whether such characters are useful in inferring phylogenetic relationships between species. Nineteen morphological characters were measured and analyzed, and species‐specific characters were identified. The morphometric data were then transformed using gap coding and a parsimony analysis was undertaken. The resulting cladogram for the tridentate pedicellariae present in species of Diadema was compared with the mitochondrial DNA phylogeny of Lessios et al., with a good level of congruence observed. Very narrow forceps‐like tridentate pedicellariae were found to be basal among Recent species, present only in D. setosum and D. palmeri. Members of D. palmeri were found to be unique within the genus, having both the forceps‐like form and a broad form of tridentate pedicellaria. The very narrow forceps‐like form is absent in all subsequent divergent species, while the broad form of tridentate pedicellaria in D. palmeri is basal to the broad forms in D. antillarum, D. mexicanum, D. paucispinum, and both the broad and narrow forms of tridentate pedicellaria of D. savignyi. The greatest similarity was found between the broad forms of tridentate pedicellaria in D. antillarum and D. mexicanum. These species were also found to have narrow forms of tridentate pedicellaria that showed a reasonable level of association to one another and to the rostrate form in D. ascensionis. Since the work of Mortensen, D. ascensionis has been shown, using mitochondrial DNA, to be nested within D. antillarum. The results of this study show that the tridentate pedicellaria in D. ascensionis are distinctly different from all other forms within the genus, to the extent that they belong to a rostrate subclass. This indicates that, among Diadema species, the tridentate pedicellariae are one of the first morphological characters to diverge in genetically isolated populations. Unlike the tridentate pedicellariae in Diadema, the different forms of tridentate pedicellariae in E. calamaris and E. diadema showed a stronger association intraspecifically than between forms interspecifically. The small forms of tridentate pedicellaria of the white and brown color morphs in E. calamaris showed a high level of association, while the large forms showed only a moderate association, far lower than would be expected between color morphs of the same species. This suggests that they are either subspecies or recently diverged separate species. This study demonstrates the taxonomic value contained within the characters of the tridentate pedicellariae for both differentiating species (even subspecies) and inferring phylogenetic relationships between species.     

Stromatoporoid palaeoecology in the Frasnian (Upper Devonian) Belgian platform,and its applications in interpretation of carbonate platform environments

Abstract: Stromatoporoid faunas in the Frasnian of southern Belgium are abundant in the carbonate platform environments present in this area. Stromatoporoids dominate the large skeletal organisms and occur principally in biostromes. The stromatoporoid assemblage is represented by a small number of taxa. Stromatoporoid genera include Actinostroma, Amphipora, Atelodictyon, Clathrocoilona, Salairella, Stachyodes, Stictostroma, Stromatopora and Trupetostroma which are present in environments ranging from the outer, outer intermediate, inner intermediate and inner zones and associated biostromes. Most large skeletal stromatoporoids are low profile, which reinforces the conclusions of previous studies that low‐profile growth forms were the most successful stromatoporoid forms. These low‐profile forms are likely to have been important sediment stabilisers that may have led to expansion of the carbonate factory. Growth forms vary between facies, indicating some degree of environmental control on form; for example, laminar in the intermediate zone, bulbous and domical in the inner and outer zones. Stromatoporoid taxa vary in occurrence across the environmental gradient from shallow to deep. There is some taxonomic control on growth forms, with some taxa showing more variability than others in different environments.     

Morphology and systematic significance of sclerolepidia in the weevils (Coleoptera: Curculionoidea)

The Russian sturgeon, Acipenser gueldenstaedtii, is closely related to three other sturgeon species (A persicus, A. naccarii and A baerii), with populations in the Caspian Sea containing a cryptic lineage with an A. baerii‐like mtDNA profile. Using morphological evidence (morphometrics, meristics) and additional genetic analysis (cytochrome b gene and control region sequencing), cryptic lineages within the Russian sturgeon and their relation to other closely related species of sturgeons are further examined. These data indicate that three genetic forms exist within what is presently known as A. gueldenstaedtii. These forms include the pure A. gueldenstaedtii and A. baerii‐like individuals plus a third rare genetic form whose mtDNA is similar to the mtDNA of the Adriatic sturgeon, A. naccarii. Morphological comparison of the three forms and the Yenisei River A baerii indicates that although the three forms of A. gueldenstaedtii are not different from one another, all three significantly differ from the Yenisei River A. baerii. Competing explanations, including translocation and centre of origin hypotheses are considered. The three geneticforms of A. gueldenstaedtii likely colonized different geographic areas during different geological periods, and subsequently evolved in these regions independently into the species currently recognized as A. gueldenstaedtii, A. naccarii and A. baerii.     

Polymorphism of the X-chromosome,Y-chromosome and autosomes in the Australian hopping mice,Notomys alexis,N. cervinus and N. fuscus (Rodentia,Muridae)

All three species of Notomys so far studied possess a diploid number of 48. Many elements in the karyotype of N. alexis are polymorphic due to variation in heterochromatin, but the variation is most marked in autosomal pair 1, which occurs in at least four forms, the X-chromosome, which occurs in three forms, and the Y-chromosome which occurs in many forms. N. cervinus is unique in the genus in possessing an entirely biarmed karyotype due mainly to the addition of heterochromatic short arms. The X-chromosome of N. cervinus occurs in three forms and the Y-chromosome in two forms. The karyotype of N. fuscus is mainly telocentric although two autosomal pairs are polymorphic due to pericentric inversions. The X- and Y-chromosomes both occur in two forms in N. fuscus. Chromosome measurements and C-banding show that most of the variation in the size and morphology of the sex-pair both within and between species is due to variation in constitutive heterochromatin.     

Regions of the cloned Vibrio cholerae rfb genes needed to determine the Ogawa form of the O-antigen.

Summary The O-antigen of the lipopolysaccharides of Vibrio cholerae 01 can exist in two forms termed Inaba and Ogawa. We used a complementation system to demonstrate that the Ogawa phenotype is dominant over the Inaba phenotype. By using a set of deletions affecting the Ogawa rfb genes, we identified two regions which are needed to confer the Ogawa phenotype. In vitro mutagenesis of the cloned Ogawa rfb genes resulted in the isolation of variants with the Inaba phenotype. The results are interpreted with respect to previous studies demonstrating interconversion between the two forms of the V. cholerae O-antigen.     

Occurrence of cytochromes in R and S yeast mutants of the genusSaccharomyces

Visible region of an absorption spectrum was followed in cells of original strains and of rough mutants ofSaccharomyces cerevisiae andS. cerevisiae var.ellipsoideus. It was found that there are no substantial differences in relative content of cytochromesb andc in aerobically grown rough and smooth yeast forms, in spite of the fact that both forms differ substantially in the metabolic oxygen quotient. If the cytochromes present were not reduced in washed cells by dithionite or by substrate addition, the rough forms exhibited a lower cytochrome b:c ratio than the smooth forms. Under anaerobic conditions of cultivation, the rough forms retained a typical aerobic spectrum, lacking, however, the cytochromea and a₃ band; the ratio of cytochromesb andc was changed in favour of cytochromeb (from the original 1.7: 1 up to 3.4: 1). The inability of the rough mutants to produce anaerobic cytochrome spectrum represented by cytochrome b₁ was connected with their inability to reproduce under anaerobic conditions.     

New evidence for the potential role of Culex pipiens mosquitoes in the transmission cycle of West Nile virus in Tunisia

Physiological and molecular characteristics of natural populations of Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) were investigated to elucidate how this species is potentially involved in the transmission of West Nile virus in Tunisia. A total of 215 Cx. pipiens females from 11 breeding habitats were analysed in the laboratory to estimate autogeny and stenogamy rates. They were tested individually for the locus CQ11 to distinguish between the two Cx. pipiens forms, pipiens and molestus. All tested Cx. pipiens populations were stenogamous. Females from underground breeding sites were all autogeneous, whereas females from above‐ground habitats were mostly anautogeneous. Of all the females tested, 59.7% were identified as pipiens, 22.4% as molestus, and 17.9% as hybrid pipiens/molestus. Furthermore, both Cx. pipiens forms and their hybrids were found to co‐occur in sympatry in all sites. The results of this study represent the first evidence that both Cx. pipiens forms and their hybrids are present in Tunisia. Because hybrids able to act as bridge vectors are present in all studied habitats, Tunisia can be considered to have a high degree of receptivity for the establishment of West Nile virus zoonotic cycles.     

Allozyme Variation of the Pygmy Wood Mouse Sylvaemus uralensis (Rodentia,Muridae) and Estimation of the Divergence of Its Chromosome Forms

The genetic divergence between the eastern European, southern European, and Asian chromosome forms of the pygmy wood mouse Sylvaemus uralensis, whose karyotypes differ from one another in the amount of centromeric heterochromatin, has been reevaluated using allozyme analysis. In general, Asian chromosome forms in S. uralensis living in eastern Kazakhstan, eastern Turkmenistan (the Kugitang Ridge), and Uzbekistan are more monomorphic than European populations of this species. However, the allozyme differences between all chromosome forms of the pygmy wood mouse are comparable with the interpopulation differences within each form and are an order of magnitude smaller than those between good species of the genus Sylvaemus. Thus, the chromosome forms of S. uralensis cannot be considered to be separate species. The concept of races as large population groups that have not diverged enough to regard them as species but differ from one another in some genetic characters is used to describe the differentiation of S. uralensis forms more adequately. The currently available evidence suggests the existence of two S. uralensis races, the Asian and the European ones, and two chromosome forms (eastern and southern) of the European race. The possible historical factors that have determined the formation of the races of the pygmy wood mouse are considered. According to the most plausible hypothesis, the shift and fragmentation of the broad-leaved forest zone during the most recent glacial period (late Pleistocene) were the crucial factors of the formation of these races, because they resulted in a prolonged isolation of the European and Asian population groups ofS. uralensis from each other.     

Psocoptera of the Mascarene Islands

Analysis of the known and recently discovered differentiation patterns of 58 forest butterfly species (of the total 66) in the tribe Heliconiini, including over 300 races and forms, has led to the drawing of a map of core areas for evolution in the group. The majority of these are not isolated by any obvious modern physiogeographic barriers to dispersal of these butterflies, and probably correspond to forest refugia during the two or three most recent Quaternary dry periods. The map is in good accord with the results of similar studies in other groups of animals (forest vertebrates and invertebrates) and in forest trees, but indicates a larger number of significant operative refugia (38) than other analyses. Bases for the understanding of differentiation patterns in polytypic continental species are developed, in accord with the refuge theory and using intensive and extensive data on local monomorphic populations and secondary contact zones between differentiated forms. The known forms discussed include: Dione juno miraculosa Hering, Eueides libitina Staudinger, Heliconius xanthocles explicata Stichel, H. eleuchia (Hewitson) and H. leucadia Bates together with a supplementary revision of the tribe giving information published since 1972. The following new forms are described: Eueides emsleyi sp. n. and nine new subspecies of Heliconius: H. aoede philipi, H. wallacei araguaia, H. pardalinus orteguaza, H.p. butleri, H. hecale australis, H.h. barcanti, H. clysonymus tabaconas, H. congener aquilionaris, H. sapho candidus. Geographical details of the refugia are given in Appendix I, and in Appendix II the heliconians are assigned to the postulated refugia.     

A tale of two haplotype groups: evaluating the New World Junonia ring species hypothesis using the distribution of divergent COI haplotypes

The New World Junonia butterflies are a possible ring species with a circum‐Caribbean distribution. Previous reports suggest a steady transition between North and South American forms in Mesoamerica, but in Cuba the forms were thought to co‐exist without interbreeding representing the overlapping ends of the ring. Three criteria establish the existence of a ring species: a ring‐shaped geographic distribution, gene flow among intervening forms and genetic isolation in the region of range overlap. We evaluated mitochondrial cytochrome oxidase I haplotypes in Junonia from nine species in the Western Hemisphere to test the Junonia ring species hypothesis. Junonia species are generally not monophyletic with respect to COI haplotypes, which are shared across species. However, two major COI haplotype groups exist. Group A predominates in South America, and Group B predominates in North and Central America. Therefore, COI haplotypes can be used to assess the degree of genetic influence a population receives from each continent. Junonia shows a ring‐shaped distribution around the Caribbean, and evidence is consistent with gene flow among forms of Junonia, including those from Mesoamerica. However, we detected no discontinuity in gene flow in Cuba or elsewhere in the Caribbean consistent with genetic isolation in the region of overlap. Although sampling is still very limited in the critical region, the only remaining possibility for a circum‐Caribbean discontinuity in gene flow is at the Isthmus of Panama, where there may be a transition from 98% Group B haplotypes in Costa Rica to 85–100% Group A haplotypes in South America.     

Observations on the taxonomic composition and vertical distribution of cyclopoid copepods in the central Red Sea

The taxonomic composition and vertical distribution of cyclopoid copepods, including very small species, in the central Red Sea were analyzed. Samples were taken in a multiple opening and closing net with 0.1 mm mesh size to a depth of 450 m. Most species belong to the genus Oncaea (13 identified and 6 unidentified forms). Nearly one half of these are smaller than 0.4 mm in length. Nine cyclopoid species and three groups of very similar species and forms of Oncaea predominate. In the upper 450 m of the water column, each of these species or groups account for more than 1 % of all cyclopoid specimens. In the epipelagic zone (0–100 m) Oithona simplex predominates, accounting for 20 % of the total. In the upper mesopelagic zone Paroithona sp. and one of the unidentified Oncaea forms are most numerous from 100 to 250 m, and two groups of Oncaea are most abundant from 250 to 450 m. The dominance of single species among cyclopoids is less pronounced than that reported for calanoids in the mesopelagic zone of the central Red Sea.     

Contributions to the knowledge of African Rotifers I. Rotifers from Senegal

24 plankton samples, collected in different parts of the Republic of Senegal (W. Africa) were examined for their rotifer content. Seventy taxa were identified to species level, some of which were present in different forms. Thirty three taxa and forms are new to Senegal, three species are new to Africa. Attention is paid to a cruciform population of Asplanchnella sieboldi and to a Brachionus quadridentatus population of very small dimensions. Two new taxa are described: Brachionus cf. angularis and Brachionus bidentatus senegalensis Koste & De Ridder.     

Historical biogeography and distribution of the freshwater cyclopine copepods (Copepoda, Cyclopoida, Cyclopinae) of the Yucatan Peninsula, Mexico

Aim To determine and analyse the distribution of the freshwater cyclopine copepod fauna of the Yucatan Peninsula (YP) and its relationship with the geological and climatic history of this Neotropical karstic zone. Location The Yucatan Peninsula, Mexico. Methods Plotting of georeferenced sites, analysis of local and regional geological and climatic history, analysis and comparison of regional and local faunistic records. Results Distinct dispersal and/or vicariant processes seem to be linked to the current distributions of the seven genera known in the YP. In general, the endemic hypogean or benthic crevicular forms (i.e. Diacyclops chakan, D. puuc and Mesocyclops chaci), derived from epigean, tropical, widely distributed forms (some of them South American) may have been among the earliest colonizers of the subterranean habitats in the YP. The distribution of these and other endemic forms seem to be related to the Holocene dry periods that desiccated the largest bodies of water and isolated local populations of different species. These vicariant processes resulted in forms with restricted distributional areas; some of these formed sister species that speciated in geographically close localities but related to a common identifiable ancestor. Overall, the processes of cyclopine colonization of the YP show the influence of the South American fauna, as the closest relatives of some species endemic to the YP are South American forms; the Nearctic influence is low. The cyclopine fauna of the YP is formed by a mixture of Nearctic‐derived (species of Acanthocyclops), Neotropical (i.e. M. edax, M. longisetus, A. panamensis, Thermocyclops inversus and T. tenuis), and epigean and hypogean endemic forms. The highly dynamic geomorphology of the YP and the recent climatic changes in the Holocene define the YP as a peculiar subregion that harbours a diverse fauna of cyclopine copepods with a high endemism. Main conclusion The current distribution of cyclopine copepods reflects relatively recent, post‐Pliocene biogeographical patterns; probably older patterns are involved as well. The eastern coast of the Yucatan is the most recently colonized by cyclopine copepods. Most of the genera are linked with South American forms, and the Nearctic influence is weakly represented. This group has no marine relatives, but there is evidence of vicariant events involving cave‐dwelling forms.     

Patterns of organizations of intertidal and shallow subtidal vegetation in wave exposed habitats of central Chile

Wave-exposed rocky intertidal habitats of central Chile exhibit zonation of algal morphologies rather than strict patterns of species zonation. In low shore areas, there is a vertical sequence of perennial belts of calcareous crusts, kelp-like forms and expanded cushions or non-calcareous crusts. The calcareous crusts are represented by species of Mesophyllum, the kelp-like forms include Lessonia nigrescens and Durvillaea antarctica, while the cushions are represented by Gelidium chilense and G. lingulatum and the noncalcareous, expanded crusts by Codium dimorphum. Thin and thick blades, represented by Iridaea laminarioides, Ulva rigida and Porphyra columbia and filamentous forms including Ceramium rubrum, Centroceras clavulatum and Polysiphonia spp. are more patchy than the lower, perennial belts. They may, however, form distinct temporal monocultures at upper intertidal levels. Upper and lower limits of the various zones are set by interactions of several factors, the relative importance of which can change seasonally. When some of the factors restricting species distribution are experimentally removed, other interactions among factors become limiting.Within each zone, species are morphologically similar, with the abundance of species being regulated by symmetric competitive interactions. Competition is often asymmetric at the boundaries of zones except when adults of small-sized forms interact with morphologically similar juveniles of larger forms. Irrespective of their extremely different morphologies, the permanent, zone-forming algal species generally combine escape from grazers or defensive adaptations with clear competitive abilities. Nevertheless, there is a clear competitive hierarchy which is expressed in vertical displacements and zonation. The lowershore habitats could potentially be occupied by any of the different types of algae. Fast growth and large size allow the kelps to occupy this zone pushing the calcareous crust dominated-zone down into shallow subtidal areas and displacing the cushions and fleshy crusts into the low and middle intertidal regions. In turn, these last forms can displace thick and thin foliose forms and filaments to upper levels on the shore. Displaced forms may exist as patches at various levels of the shore.     

Identification of two forms of the maltose transport system in Saccharomyces cerevisiae and their regulation by catabolite inactivation

The maltose transport system of Saccharomyces cerevisiae exists in two forms with K_m values of approx. 4 mM and 70 mM, respectively. The V_max of the high-K_m form is about 4-fold greater than the V_max of the low one. A rapid and irreversible inactivation of both forms is detected on protein synthesis impairment. This inactivation is stimulated by the catabolism of fermentable sugars and prevented during ethanol catabolism. It is concluded that both forms of the maltose transport system are regulated by catabolite inactivation.     

Plant management among the Nahua and the Mixtec in the Balsas River Basin,Mexico: An ethnobotanical approach to the study of plant domestication

Different forms of management of wild, weedy, and domesticated plants carried out by the Nahua and the Mixtec in the Balsas River Basin, Mexico, are described. Along with cultivation of domesticated plants, these forms of plant management include gathering from wild populations; in situtolerance of plant individuals during clearings of natural vegetation; in situenhancement and protection of particular plants among populations of some species; as well as sowing or planting of propagules and transplantation of complete individuals of weedy and wild plants in controlled ex situenvironments. Processes of artificial selection and possible routes of domestication occurring in these forms of plant management are discussed.