Properties of paper made from fibers of hesperaloe funifera (Agavaceae)

The long, thin fiber cells of Hesperaloe funifera have been identified as having potential value in paper-making, although no studies to date have reported data on their technical strength properties in test papers. This study summarizes evaluations done by the Herty Foundation on Hesperaloe fiber. Tensile strength, burst strength, and tear strength of paper made from Hesperaloe are significantly greater than those of softwood kraft, the industry standard. Tensile and burst strength of Hesperaloe pulps are also higher than those of abaca or sisal, two high-value specialty fibers; tear strength is somewhat lower in Hesperaloe. The fibers of Hesperaloe were processed in two ways-using a decorticator or using a roller mill. Pulp obtained from the decorticated leaf fibers had higher strength properties.     

Chemistry and geographic variation of floral scent in Yucca filamentosa (Agavaceae)

We identified volatiles from the floral headspace of Yucca filamentosa using gas chromatography and mass spectrometry and analyzed floral scent composition and variation among populations pollinated by different yucca moth species. Twenty-one scent compounds were repeatedly identified and most could be categorized into two major classes: (1) homoterpenes derived from the sesquiterpene alcohol nerolidol and (2) long chain aliphatic hydrocarbons. Two biosynthetic pathways are thus responsible for the majority of floral volatiles in Y. filamentosa. The homoterpene E-4,8-dimethylnona-1,3,7-triene, which is released systemically by higher plants upon herbivory, was the most abundant compound. Two di-oxygenated compounds not previously reported as floral compounds also were detected. No differentiation in floral scent was observed between populations pollinated by different yucca moths, nor was there any correlation between chemical distance and geographic distance among populations. The total release rate of volatiles differed significantly among populations, but not between populations with different pollinators. The combination of unique compounds and low variation in the fragrance blend may reflect highly selective attraction of obligate pollinators to flowers. The observed lack of differentiation in floral scent can putatively explain high moth-mediated gene flow among sites, but it does not explain conservation of odor composition across populations with different pollinators.     

Intraspecific volatile oil variation in Myrceugenia cucullata (Myrtaceae)

The analysis of volatile oil content of Myrceugenia cucullata, a treelet from southern Brazilian montane forests, was investigated. Two markedly distinct chemotypes were identified. One of them is dominated by (E)-nerolidol and the other by (−)-α- and (−)-β-pinenes. Field observations showed a distinct ecological behaviour of plants with distinct chemical compositions, and a closer morphological analysis hints to a possible separation of them. The diverse oil composition is discussed and the possibility of specific segregation of the chemotypes is commented.     

Gibberellin-Induced Flowering in Cordyline (Agavaceae)

Normal, terminal inflorescences of Cordyline terminalis, a woodymonocotyledon, appeared 4–6 weeks after apical buds weretreated with gibberellin A₃ (GA₃) or GA₄₊₇. There was no responseto GA₁₃. Large plants, newly rooted cuttings, and seedlingsall responded, although there were clonal differences. Floweringwas induced under natural day lengths throughout the year. Untreatedcontrol plants in all experiments remained vegetative. Dracaenaspp. did not respond to the three gibberellins.     

Intraspecific variation and evolutionary trends in Capparis spinosa L. (Capparaceae)

 In order to investigate the variability of the polymorphic Capparis spinosa L., a comparative study was carried out in Sicily on subsp. spinosa and subsp. rupestris. Autecology, phenology, quantitative morphology, plant architecture and leaf development of several populations were examined. These data reveal a parapatric distribution of the two subspecies and support their present taxonomic treatment. Subsp. spinosa is widespread on clay soils and shows remarkable intrapopulational variation. It is characterized by shortened reproductive and vegetative periods, high shoot growth rate, winter-desiccating shoot system and stipular thorns. Subsp. rupestris, less variable and linked with carbonatic and volcanic outcrops, shows prolonged phenological patterns, slow growth rate, woody habit and caducous stipules. A noteworthy phenotypic convergence with subsp. rupestris was observed in individuals of subsp. spinosa growing in rocky habitats. The evolutionary trends of Capparis spinosa in the Mediterranean region are discussed. Received March 29, 2000 Accepted April 6, 2001     

Intraspecific variation in ejaculate traits of the northern watersnake (Nerodia sipedon)

Sperm competition occurs when the sperm of more than one male compete to fertilize the eggs of a female. In reptiles, sperm competition is particularly prevalent and is an important agent of sexual selection in males. Spermatogenesis in reptiles can be energetically expensive, suggesting that there may be costs to producing high-quality ejaculates. The northern watersnake Nerodia sipedon has a mating system characterized by aggregations in which a single female mates with multiple males, resulting in high levels of multiple paternities. Under these circumstances sperm competition is likely important, and selection should favour sperm and ejaculate traits that enhance a male's reproductive success. In this study, we examined intraspecific variation in ejaculate quality (sperm length, motility, sperm density, spermactocrit) in male watersnakes and determined whether ejaculate traits varied with body size and condition, using both size-corrected mass and haematocrit as indices of condition. We found large variation among males in all these traits, except for sperm length. Although there was significant variation in sperm length among males, the majority of variation in sperm length occurred within rather than among individuals. Males with high haematocrit had sperm that were less variable with respect to length, and large males produced ejaculates that were less concentrated with respect to sperm than small males. The lack of condition dependence of most ejaculate traits is consistent with previous studies that indicate that male reproductive effort in this species is generally not energy limited, perhaps because of opportunistic foraging during the mating season.     

Intraspecific red cell enzyme variation in the pigtailed macaque (Macaca nemestrina)

The erythrocytes of 350 pigtailed macaques (Macaca nemestrina) were examined for electrophoretic variation of hemoglobin and 26 enzymes. Seven enzymes showed variation in more than 1% of individuals: phosphoglucose isomerase, phosphoglucomutase-1, soluble NADP-dependent isocitric dehydrogenase, peptidase A, peptidase C, 2,3-diphosphoglycerate mutase, and acid phosphatase. Variation with lesser frequency was found in soluble glutamic-oxalacetic transaminase, phosphoglycerate kinase, lactic dehydrogenase, and hemoglobin. Only eight samples were tested for esterase D, and one of these had a variant phenotype. Enzymes with no clear variation were adenylate kinase, adenosine deaminase, phosphofructokinase, hexokinase, pyruvate kinase, glyceraldehyde 3-phosphate dehydrogenase, aldolase, phosphoglycerate mutase, phosphopyruvate hydratase (enolase), phosphoglucomutase-3, and superoxide dismutase. There was father-to-son transmission of PGI, PGM-1, peptidase C, 6PGD, 2,3-DPGAM, NADP-ICD, and acid phosphatase variants, suggesting that these loci are autosomal as in man.     

Intraspecific life-history variation in Radix plicatulus (Gastropoda: Pulmonata: Lymnaeidae)

Life-histories of Radix plicatulus (Benson, 1842) populations inhabiting two neighbouring sites on a Hong Kong stream were investigated. In one of the two sites, R. plicatulus co-occurred with high densities of Pomacea levior which is known to prey on the egg capsules and hatchlings of sympatric gastropods. On the basis of general life-history theory, I hypothesized that R. plicatulus which co-occurred with P. levior should exhibit a life-history strategy characterized by a delayed reproduction, a longer recruitment period and a larger number of breeding bouts per year as compared with contemporaries inhabiting the other site with low P. levior abundance. Reproductive patterns of the two populations observed in the field accorded with the expectations of general life-history theory, and lent support to the hypothesis. However, laboratory culture experiments revealed no evidence of a genetic basis for the interpopulation differences. The importance of establishing a genetic basis for the interpopulation divergence before invoking an evolutionary explanation was discussed.     

Intraspecific variation of Myzus persicae on sugar beet (Beta vulgaris)

Differences in inherited resistance among seven sugar-beet stocks had similar effects on Myzus persicae clones representing the range of variation in aphid response to resistant and susceptible sugar beet observed in fifty-eight clones collected between 1969 and 1971. Three sugar-beet stocks were consistently resistant. Statistically significant interactions between beet stocks and aphid clones did not indicate the existence of biotypes with specific abilities to overcome resistance. M. persicae clones differed in their vigour of colonizing sugar beet, irrespective of the differences between beet stocks. The readiness of adult aphids to settle determined the size of aphid population produced and included a component related to the response of the aphid clone to sugar beet as a host, and a component related to the resistance ranking of the beet stock. Breeding sugar beet with resistance to aphids will be simplified, as the results indicate that, at present, differences between aphid biotypes need not be considered a problem.     

Intraspecific variation in life history traits of Viola brevistipulata (Violaceae) in Hokkaido

Intraspecific life‐history variations of Viola brevistipulata var. brevistipulata were examined with special reference to reproductive features based on quantitative and qualitative monitoring of chasmogamous (CH) and cleistogamous (CL) flowers. We selected 10 populations in southwestern Hokkaido in common deciduous forests, and marked 40–70 individual plants at each population. Marked individuals were monitored every 1–2 weeks. The expression of CH and CL flowers was distinct among the populations. That is, there were populations consisting of plants with only CH flowers, while other populations produced CL flowers after CH flowers with greater shoot longevity This phenomenon was observed even in populations located at the same site. The results suggest that V. brevistipulata var. brevistipulata shows distinct life‐history variations among the populations.     

Intraspecific variation in samara morphology and flight behavior in acer saccharinum (Aceraceae)

We studied intraspecific variation in samara morphology and flight behavior within and among parent trees of Acer saccharinum (silver maple), with a particular focus on the effect of samara shape. Samara mass, area, wing loading, and descent rate from a 4.5-m indoor balcony were measured for 50 undamaged mature samaras from each of six parents. We found significant differences among parental types for all morphological variables and descent rate. These differences yielded a 50% range in mean dispersal potential among the six parents. There was a strong linear correlation between descent rate and square root of wing loading when mean values were plotted for each of the six parental types. But there was considerable within-parent variation for all measured variables, including substantial nonallometric variation in wing loading caused in part by poor correlations between wing area and fruit weight. Parents also differed widely in the relationship between square root of wing loading and descent rate (linear r² = 0.150-0.788), with one parental type showing no significant relationship. Fruits from the same parent with similar values of the square root of wing loading showed as much as a 75-100% difference in descent rate. The usefulness of mass : area indices such as wing loading is limited by its exclusion of aerodynamically important factors such as mass distribution and wing shape, which in our case caused the six parents to behave aerodynamically almost as if they were six separate species.     

The caudal skeleton of ostariophysan fishes (Teleostei): Intraspecific variation in trichomycteridae (Siluriformes)

The different elements of the caudal skeleton of the South American catfish genera Nematogenys (Nematogenyinae) and Trichomycterus, Hatcheria, and Bullockia (Pygidiinae) (Siluriformes, Trichomycteridae) show Ontogenetic transformation of the second ural centrum in Trichomycteridae separates the subfamilies Nematogenyinae and Pygidiinae. In the former, the second ural centrum is aligned with the first ural centrum in early stages of ontogeny; it is not fused with the bases of hypurals 3 and 4 in any stage of development. In the Pygidiinae, in contrast, the second ural centrum is connected with the base of hypural 3 from an early stage of development on. One of the most noteworthy features of the Pygidiinae is the epural, a polymorphic element with three or four morphotypes that are species specific. The primitive catfish Nematogenys shows intraspecific variation in the ural centra, segmentation of procurrent caudal rays, and principal caudal ray formulae. Species of Trichomycterus, Hatcheria, and Bullockia are characterized by great intraspecific variability that involves ural centra, the epural, hypurapophyses, and the neural arches of the compound centrum. There is intraspecific variation in the fusion of the hypurals in some species of Trichomycterus. Intraspecific variation of the caudal skeleton of fishes of the family Trichomycteridae involves the presence and frequency of different morphotypes of the epural, neural arch of the compound centrum, fusion of hypurals, and principal caudal ray formulae. Ontogenetic changes of the first and second ural centra, hypurapophyses (with the exception of Nematogenys), and segmentation of procurrent caudal rays (in Nematogenys) are involved also.     

Intraspecific sequence variation in the mitochondrial genome of rainbow trout (Oncorhynchus mykiss)

We examined the sequence of a 2214 base pair HindIII fragment from the mitochondrial genome of six rainbow trout. The fragment encodes four proteins and two tRNAs. Sequences for two fish from a single locality were identical. Those from separate localities differed by from 1 to 7 nucleotide substitutions. Of 13 variable sites, 12 were synonymous and 1 led to a conservative amino acid substitution. Transitions accounted for 12 of the 13 variants. In contrast to interspecific comparisons (Thomas and Beckenbach. 1989. J. Mol. Evol. 29: 233-245), the intraspecific divergence estimates based on sequence are less than those estimated from restriction fragment analysis, suggesting a complex, dynamic process for the accumulation of variation in the mitochondrial genome.     

Intraspecific 5S rRNA gene variation in flax,Linum usitatissimum (Linaceae)

A relatively large proportion of the flax genome (~ 3%) is comprised of 5S rRNA genes. This study focuses on the intraspecific sequence variation among five distinct groups of 5S rRNA genes. The results indicate that group 1 and 2 5S rRNA genes most closely resemble other angiosperm 5S genes, while groups 3–5 are highly divergent. Sequence variation is higher in the spacer region compared to the transcribed region for all pairwise comparisons. The large degree of sequence variation observed in this study is discussed with respect to genome organization and proposed models for repetitive sequence maintenance.     

Intraspecific nuclear DNA variation in Drosophila

We have summarized and analyzed all available nuclear DNA sequence polymorphism studies for three species of Drosophila, D. melanogaster (24 loci), D. simulans (12 loci), and D. pseudoobscura (5 loci). Our major findings are: (1) The average nucleotide heterozygosity ranges from about 0.4% to 2% depending upon species and function of the region, i.e., coding or noncoding. (2) Compared to D. simulans and D. pseudoobscura (which are about equally variable), D. melanogaster displays a low degree of DNA polymorphism. (3) Noncoding introns and 3' and 5' flanking DNA shows less polymorphism than silent sites within coding DNA. (4) X-linked genes are less variable than autosomal genes. (5) Transition (Ts) and transversion (Tv) polymorphisms are about equally frequent in non-coding DNA and at fourfold degenerate sites in coding DNA while Ts polymorphisms outnumber Tv polymorphisms by about 2:1 in total coding DNA. The increased Ts polymorphism in coding regions is likely due to the structure of the genetic code: silent changes are more often Ts's than are replacement substitutions. (6) The proportion of replacement polymorphisms is significantly higher in D. melanogaster than in D. simulans. (7) The level of variation in coding DNA and the adjacent noncoding DNA is significantly correlated indicating regional effects, most notably recombination. (8) Surprisingly, the level of polymorphism at silent coding sites in D. melanogaster is positively correlated with degree of codon usage bias. (9) Three proposed tests of the neutral theory of DNA polymorphisms have been performed on the data: Tajima's test, the HKA test, and the McDonald-Kreitman test. About half of the loci fail to conform to the expectations of neutral theory by one of the tests. We conclude that many variables are affecting levels of DNA polymorphism in Drosophila, from properties of nucleotides to population history and, perhaps, mating structure. No simple, all encompassing explanation satisfactorily accounts for the data.      

Intraspecific variation in biocontrol traits in Mastrus ridens (Hymenoptera: Ichneumonidae) laboratory populations

Breeding natural enemies to generate populations with improved characteristics is an attractive idea, particularly nowadays with the increase in use of biological control and the availability of modern molecular and genetic tools. A first step in the process is to characterize traits which can be important for biological control and their intraspecific variation. In this study we characterized fecundity, longevity and dispersal-related traits of four endogamic and three exogamic laboratory populations (lines) of Mastrus ridens, an important parasitoid of the codling moth (Cydia pomonella (L.)). We found that several traits were positively correlated and that there was variability among lines and between endogamic and exogamic lines. Exogamic lines presented a better combination of trait values than endogamic lines. The absence of trade-offs among the traits studied in M. ridens would be advantageous for a breeding program. Nevertheless, it would be important not to lose genetic variability in the process, because of the presence of complementary sex determination (CSD) and negative effects of inbreeding on other traits. The results of this study could be useful for the selection of M. ridens lines with better traits and as preliminary information for breeding programs.

     

Intraspecific variation and phylogeographic patterns of Fagus crenata (Fagaceae) mitochondrial DNA

Mitochondrial (mt) DNA variation in Japanese beech, Fagus crenata (Fagaceae), was studied in 17 populations distributed throughout the species' range. Total genomic DNA of samples from single trees representing each of 12 populations were digested with 18 restriction enzymes and hybridized with three probes containing coxI, coxIII, and atpA gene sequences. Thirty-four of the 54 enzyme/probe combinations showed polymorphisms and all the individuals were subsequently analyzed with six combinations of three probes and two enzymes. Restriction fragment length polymorphisms were evident around all three genes, allowing the identification of eight distinct haplotypes. Haplotype diversity within the populations was found to be very low (HS = 0.031), but population differentiation to be much higher (GST = 0.963). The mtDNA variation was strikingly different from allozyme variation (HS = 0.209; GST = 0.039). Gene flow for maternally inherited mtDNA should be restricted to seed dispersal while nuclear gene flow occurs by both seed and pollen dispersal. Therefore, the difference in the variation between mtDNA and allozymes may be largely a result of the much higher rate of gene flow associated with pollen dispersal than with seed dispersal. The mtDNA variation displayed strong geographic structure, which may reflect the species' distribution in the last glacial maximum and subsequent colonization, and probably also reflects intraspecific phylogeography of the species.     

New varietal combinations in Agave vivipara (Agavaceae)

New varietal combinations are made inAgave vivipara forA. deweyana, A. letonae, A. nivea, A. rubescens andA. angustifolia var.sargentii. A. angustifolia var.marginata andA. angustifolia var.variegata are transferred toA. vivipara as cultivars.