Isozymes

Carex vulpina and C. otrubae are difficult species to distinguish using floral characters. As an alternative, SEM of the nutlet surface, stomatal morphology and isozymes have been used as taxonomic tools to distinguish between the two taxa. The three methods show differentiation along species lines and are suitable to identify hybridisation. Stomatal morphology and isozymes reveal evidence of possible introgression between the two species.

The genetic variation and relationships among 16 pumpkin accessions of Cucurbita moschata & Cucurbita maxima were assessed based on variation in fruit shape, skin color, flesh and size of fruits. Polyacrylamide gel electrophoresis of seed protein and molecular markers revealed by SCoT and ISSR techniques. The SDS-PAGE electropherogram showed 12 bands; two (75 and 145 kDa) were found in accessions (1-8) and one (85 kDa) was found in accessions 9-16.  Other three bands were unique to accessions 1, 2 & 11. Five ISSR primers produced 79 markers ranging in molecular size from 130 to 2140 bp. Six SCoT primers produced 173 markers ranging from 135 to 2660 bp. The ISSR polymorphism among the examined accessions was 100% in the case of primers 49A, 44 B and HB-12, and was 92% for primer HB-15. Similarly, 100% polymorphism was scored for the primers SCoT8, SCoT11, SCoT12 and SCoT14. The lowest polymorphism was 93.94% in case of primer SCoT1. Our data based on protein, RAPD and ISSR data using the SYSTAT version 7.0 program clearly distinguished accessions from each other.

Nothofagus pumilio is the dominant and almost ubiquitous tree species in mountainous environments of temperate South America. We used two types of molecular markers (cpDNA and isozymes) to evaluate the effects of the Paleogene paleogeography of Patagonia and more recent climatic oscillations of the Neogene on such cold-tolerant species’ genetic makeup. Phylogeographic analysis on sequences of three cpDNA non-coding regions at 85 populations yielded two latitudinally disjunct monophyletic clades north and south of c. 42°S containing 11 and three haplotypes, respectively. This indicates a long-lasting vicariant event due to the presence of an extended open paleobasin at mid latitudes of Patagonia. Also distribution patterns of cpDNA haplotypes suggest regional spread following stepping-stone models using pre-Cenozoic mountains as corridors. Comparable genetic diversity measured along 41 sampled populations using seven polymorphic isozyme loci provides evidence of local persistence and spread from multiple ice-free locations. In addition, significantly higher heterozygosity and allelic richness at high latitudes, i.e. in areas of larger glacial extent, suggest survival in large and isolated refugia. While, higher cpDNA diversity in lower latitudes reflects the complex orogeny that historically isolated northern populations, lower isozyme diversity and reduced FST values provide evidence of local glacial survival in numerous small locales. Therefore, current genetic structure of N. pumilio is the result of regional processes which took place during the Tertiary that were enhanced by contemporary local effects of drift and isolation in response to Quaternary climatic cycles.

Hypotheses of tree survival in refugia or long-distance postglacial migration can be disentangled combining genetic polymorphisms and ecological niche modeling. This is particularly relevant for ecologically distinct taxa which are undistinguishable by pollen morphology in fossil records. We hereby test the long-term persistence of the cold-hardy Nothofagus pumilio at high latitudes in southern South America during glacial cycles. Modern and past (LGM) ecological niche modeling (ENM) for N. pumilio was developed using current climate data and including 19 bioclimatic variables and topography. We collected fresh tissue for isozyme analysis from 14 locations within Tierra del Fuego selected on the basis of their location relative to LGM glacier extent: ice-free, ice-margin, and formerly glaciated areas. We resolved 11 isozyme loci and calculated within-population genetic diversity and among-population divergence parameters. Glacial effects on population structure were analyzed by UPGMA and Bayesian models. ENM yielded distinct areas in eastern and interior Tierra del Fuego exceeding > 0.3 probability values that would have been suitable for N. pumilio during the LGM. Populations within formerly glaciated areas hold lower genetic diversity and thus were affected by genetic drift during colonization from refugia. Our data provided no evidence for wide-ranging postglacial colonization from warmer northern locales and suggested local survival of Nothofagus forests at southern-most South America.

The Bulbophyllum exaltatum complex comprises 15 described taxa, and present a number of unresolved taxonomic questions, especially among populations found in the Brazilian campo rupestre vegetation. Allozymes were examined in 33 populations to determine the degree of genetic variability between them and their degree of differentiation to better define the taxa of this group. Additionally morphometric analyses were also performed on representatives of 24 populations. All of the populations examined demonstrated high levels of variability and none of the species formed distinct groups comprising all of the conspecific populations. However, the populations primarily grouped according to their regional occurrence, with a distinction between populations of the states of Minas Gerais and Bahia, which coincided with the geophysical disjunction of the mountain chains where they occur. It is probable that hybridization or incipient differentiation is contributing to the elevated genetic identity observed among the populations, generating a reticulated grouping pattern.

Genetic relationships were studied among four taxa in the genus Chaenomeles using isozyme analysis. The band patterns obtained with six polymorphic isozyme systems provided 108 reliable markers, which were scored as unordered multistate traits. A cluster analysis as well as a multidimensional scaling analysis grouped the taxa in agreement with previously published results obtained with RAPD (random amplified polymorphic DNA) analysis; C. japonica and C. cathayensis were the most distantly related species, whereas C. speciosa took an intermediate position together with the hybrid taxon C. x superba. Similarity matrices obtained with isozymes and RAPDs, respectively, were closely correlated, r = 0.74. The previously noted low level of RAPD variability in C. cathayensis was indicated also with isozymes. However, the isozyme data were less efficient than the RAPD data for intraspecific grouping of the genotypes according to the origin of the plant material.

... thesis, Universite du Quebec & Montreal, Montreal. 6. Crawford, DJ (1983) in Isozymes in Plant Genetics and Breeding (Tansley, SD and Orton, TJ, eds), p. 257. Elsevier, Amsterdam. ... J. Bot. 74, 1614. 9. Hamrick, IL, Linhart, LB and Mitton, JB (1979) Ann. Rev. Ecol. Syst. 10, 173. ...

The Bulbophyllum exaltatum complex comprises 15 described taxa, and present a number of unresolved taxonomic questions, especially among populations found in the Brazilian campo rupestre vegetation. Allozymes were examined in 33 populations to determine the degree of genetic variability between them and their degree of differentiation to better define the taxa of this group. Additionally morphometric analyses were also performed on representatives of 24 populations. All of the populations examined demonstrated high levels of variability and none of the species formed distinct groups comprising all of the conspecific populations. However, the populations primarily grouped according to their regional occurrence, with a distinction between populations of the states of Minas Gerais and Bahia, which coincided with the geophysical disjunction of the mountain chains where they occur. It is probable that hybridization or incipient differentiation is contributing to the elevated genetic identity observed among the populations, generating a reticulated grouping pattern.

Caiman latirostris (yacare overo) es una de las dos especies de cocodrilianos citadas para nuestro pais. Sus poblaciones silvestres son objeto de manejo en Argentina, mediante programas que utilizan el sistema de ranching (cosecha de huevos silvestres para cria en granjas), para su uso sustentable y la conservacion de su habitat. C. latirostris, en nuestro pais, se encuentra en el Apendice II de CITES, el cual permite el comercio regulado de su cuero y carne, y se ha convertido en una especie de gran importancia comercial, a nivel nacional e internacional. Esta tesis incluye estudios genetico-poblacionales del yacare overo en la provincia de Santa Fe, Argentina. Se realizaron analisis de variabilidad, diferenciacion y estructura genetica empleando isoenzimas, marcadores RAPD y caracteres morfometricos, y un estudio de paternidad utilizando marcadores microsatelites. Los resultados obtenidos indican que las poblaciones analizadas de yacare overo poseen valores de variabilidad genetic...

We estimated similarity and differences at the level of isozymes among populations of Malva alcea from various habitats and parts of Central Europe. Our analyses revealed the activity of 8 enzyme systems: 6 polymorphic (PGI, IDH, PX, DIA, PGM, SHD KB) and 2 monomorphic (GOT, ME). The mean number of alleles per locus is 2.12. Nei's genetic distances among populations are small, not exceeding 0.3. Mean values of Nei's genetic simi-larity are typical of populations of the same species. Grouping by UPGMA based on Nei's genetic distances showed that the distinguished groups are only partly correlated with geographic region.