In two distinct survey areas, offshore from the Farallon Islands and in the vicinity of Pioneer Canyon off central California, Diaphus theta was significantly more prone to infection by the parasitic ...copepod Cardiodectes medusaeus than Tarletonbeania crenularis. In addition, D. theta was more heavily parasitized in the Pioneer Canyon area than in the Farallon Islands area. A linear relationship was shown between log^sub e^-transformed otolith size and log^sub e^-transformed SL and between log^sub e^-transformed dry weight and log^sub e^-transformed SL for D. theta and T. crenularis in both survey areas. A test of slopes showed differences between the two survey areas for both species. Lower dry weights were observed for both D. theta and T. crenularis, in parasitized versus non-parasitized specimens in the Pioneer Canyon area. In the Farallon Islands area, however, no differences were observed. Larger otolith sizes were observed in parasitized D. theta versus non-parasitized specimens in the Pioneer Canyon area, while no differences were observed in the Farallon Islands area. In contrast, T. crenularis had larger otolith sizes in parasitized versus non-parasitized specimens in the Farallon Islands area, while no significant differences were observed in the Pioneer Canyon area. These findings provided evidence of geographic and interspecific variability in both the prevalence and the physiological effects of parasitism.PUBLICATION ABSTRACT
D. Holá, K. Frimlová, M. Kočová, H. Marková, O. Rothová, and L. Tůmová.
Obsahuje bibliografické odkazy
The effects of 20-hydroxyecdysone on the primary photosynthetic processes (PPP) were examined ...across twelve plant species using the OJIP chlorophyll fluorescence analysis. Our experiments brought evidence that the ecdysteroids can function not only as protective compounds in plants but participate also in the regulation of photosynthesis. Exogenously applied 20-hydroxyecdysone positively affected the PPP particularly in French bean and canola. Contrary to this, the PPP were negatively influenced by 20-hydroxyecdysone in pea, sunflower, and wheat. The performace of the oxygen-evolving complex, the excitonic connectivity among PSII units, the electron transport between PSII and PSI, the size of the pool of the end electron acceptors, and the absorption and trapping of the excitation energy in the light-harvesting antennae were differently affected in individual plant species. Additionally, the older and younger leaves did not respond to 20-hydroxyecdysone in the same way and this was also a species-specific phenomenon.
Variation in leaf size (area per leaf) and leaf dry weight per area (LWA) in relation to species shade- and drought-tolerance, characterised by Ellenberg's light (ELD) and water demand (EWD) values, ...respectively, were examined in 60 temperate woody taxa at constant relative irradiance. LWA was independent of plant size, but leaf size increased with total plant height at constant ELD. Canopy position also affected leaf morphology: leaves from the upper crown third had higher LWA and were larger than leaves from the lower third. Leaf size and LWA were negatively correlated, and leaf size decreased and LWA increased with decreasing species shade-tolerance. Mean LWA was similar for trees and shrubs, but trees had larger leaves than shrubs. Furthermore, all relationships were altered by plant growth-form: none of the qualitative tendencies was significant for trees. This implies the considerably lower plasticity of foliar parameters in trees than those in shrubs. Accordingly, shade-tolerance of trees, having relatively constant leaf structure, may be most affected by the variability in biomass partitioning and crown geometry which influence foliage distribution and spacing and finally determine canopy light absorptance. Alteration of leaf form and investment pattern for construction of unit foliar surface area which change the efficiency of light interception per unit biomass investment in leaves, is a competitive strategy inherent to shrubs. EWD as well as wood anatomy did not control LWA and leaf size, though there was a trend of ring-porous tree species to be more shade-tolerant than diffuse-porous trees. Since ring-porous species are more vulnerable to cavitation than diffuse-porous species, they may be constrained to environments where irradiances and consequently evaporative demand is lower.
Sexual hybrids from S. commersonii and S. tuberosum were used in a backcross breeding scheme which involved as recurrent parent four different S. tuberosum genotypes. These genotypes had different ...origins and different morphological characteristics. In order to improve the backcross scheme, the genotypes were evaluated by RFLP and RAPD markers, which allowed us to define the genetic relationships existing among them. Both kinds of molecular markers detected roughly the same level of polymorphic markers (71.8% and 67.9% for RFLPs and RAPDs, respectively) and of polymorphic bands (50.7% and 51.9% for RFLPs and RAPDs, respectively) among the S. tuberosum genotypes. Interspecific and intraspecific similarity indexes were also calculated by RFLPs and RAPDs. The interspecific values ranged from 0.191 to 0.227, whereas the intraspecific values were always greater than 0.500. These data confirmed the clear taxonomic distinction existing between the two species S. commersonii and S. tuberosum, and also provided evidence for the existence of a considerable extent of genetic variability among the four S. tuberosum used
Ibridi sessuali derivanti da S. commerssonii e S. tuberosum sono stati utilizzati in uno schema di miglioramento per incrocio di ritorno che prevedeva come parentali ricorrenti quattro genotipi diversi di S. tuberosum. Questi genotipi avevano origini diverse e presentavano caratteri morfologici differenti. Al fine di migliorare lo schema di incrocio di ritorno, i genotipi sono stati valutati con marcatori RFLP e RAPD, che ci consentivano di definire le relazioni genetiche esistenti fra gli stessi. Ambedue i tipi di marcatori molecolari consentivano approssimativamente l'individuazione dello stesso livello di marcatori polimorfici (71,8% e 67,9% per gli RFLP e i RAPD, rispettivamente) e delle bande polimorfiche (50,7percent e 51,9% per gli RFLP e i RAPD, rispettivamente) fra i genotipi di S. tuberosum. Mediante gli RFLP e i RAPD sono stati pure calcolati gli indici di somiglianza interspecifica e intraspecifica. I valori interspecifici oscillavano da 0,191 a 0,227, mentre i valori intraspecifici erano sempre maggiori di 0,500. Questi dati hanno confermato la chiara distinzione tassonomica fra le due specie S. commersonii e S. tuberosum e hanno pure consentito di evidenziare l'esistenza di un livello considerevole di variabilita' genetica fra i quattro S. tuberosum utilizzati
