scholarly journals First Report of Puccinia xanthii on Xanthium italicum in Eastern Hungary

Plant Disease ◽  
2003 ◽  
Vol 87 (12) ◽  
pp. 1536-1536 ◽  
Author(s):  
I. Dávid ◽  
P. Harcz ◽  
G. J. Kövics
Keyword(s):  
Leaf Disc ◽  
High Density ◽  
Pathogenicity Test ◽  
Low Density ◽  
Weed Species ◽  
Row Crops ◽  
First Report ◽  
High Density Population ◽  
Noxious Weed ◽  
Density Population

In 2002, in Debrecen, eastern Hungary, Puccinia xanthii Schwein. was detected on hunter burr, a geographically spreading, noxious weed species in row crops. Symptoms were found on leaves, stems, and petioles of plants collected from a competition experiment between sugarbeet and hunter burr. Density of the hunter burr population (6 plants per m2 or 20 plants per m2) influenced the rate of infection. In the low-density population, the number of rust pustules and infected leaves was lower than that in the high-density population, in which 70% infection was reached by September. First symptoms appeared at the end of July (high-density population) and in the beginning of August (low-density population) in the form of small, chlorotic raised spots on the underside of the leaves. Dark brown telia (3.8 mm in diameter or larger) developed on spots. Elliptical telia occurred at the rate of 0.02 to 2.37 pustules per cm2. Elongated pustules caused swelling and epidermal splitting on stems and petioles. Teliospores were brown, two-celled, and 35 to 56 × 15 to 21 μm, the walls were 0.8 to 1.0 μm at the side and 5 to 8 μm at the apex, the septum was 1 to 1.5 μm, and a persistant pedicel was 15 to 50 μm. Size and morphology of teliospores fit the description of P. xanthii (2). A pathogenicity test was conducted in the greenhouse (24°C with high relative humidity) according to the “leaf disc method” of Morin et al. (1) using freshly collected hunter burr leaves. Teliospores germinated immediately, producing metabasidia, and basidiospores were produced within 5 h. The first macroscopic symptoms on test plants were observed 4 days after inoculation. Approximately 8 days after inoculation, developing telia arose from the thallus and began to erupt through the epidermis. Developed teliospores on artificially inoculated plants were morphologically identical to those from leaves collected in the field. Control plants did not develop symptoms. This microcyclic rust occurs in several regions of the world, including several southern European countries. This rust is a potential biological agent for the control of Xanthium spp.; however, it can infect several cultivars of sunflower (1). To our knowledge, this is the first report of P. xanthii in Hungary. References: (1) L. Morin et al. Can. J. Bot. 71:959, 1993. (2) J. A. Parmelee. Can. J. Bot. 47:1391, 1969.

An experimental study of the behavior of blue grouse (Dendragapus obscurus). I. Differences between the founders from three populations

1975 ◽  
Vol 53 (9) ◽  
pp. 1222-1237 ◽  
Author(s):  
Arthur T. Bergerud ◽  
H. Dennis Hemus
Keyword(s):  
Vancouver Island ◽  
Mirror Image ◽  
High Density ◽  
The Other ◽  
Low Density ◽  
Single Population ◽  
High Density Population ◽  
Dendragapus Obscurus ◽  
Field Workers ◽  
Density Population

In 1970 the authors compared the behavior of two low-density populations of blue grouse (Dendragapus obscurus) with the behavior of a high-density population on Vancouver Island. They then introduced individuals from these populations onto four islands and compared the behavior of these founders in 1971 and 1972.One island received founders from all three populations, while the other three islands each received founders from a single population. Birds from two low-density populations were quite observable, and displayed frequently when approached by field workers, both at their capture sites on Vancouver Island and in different habitats on the release sites on islands. The high-density population was much less observable, and displayed less frequently than did the two low-density populations, both at the capture sites and on the release islands. Male founders from the low-density populations were more aggressive in interacting with their mirror image than were males from the high-density population. Male founders from the high-density population dispersed less from the release sites, had smaller territories, and settled closer together than did males from the two low-density populations. These findings are consistent with the view that animals have a form of behavior that spaces them out as numbers rise, and so prevents unlimited increase in numbers.

The natural regulation of giant tortoise populations on Aldabra Atoll: recruitment

1979 ◽  
Vol 286 (1011) ◽  
pp. 177-188 ◽  
Keyword(s):  
High Density ◽  
Annual Rainfall ◽  
Egg Mass ◽  
First Year ◽  
Low Density ◽  
Isolated Populations ◽  
High Density Population ◽  
Density Area ◽  
Low Density Area ◽  
Density Population

The reproductive ecology of the giant tortoise ( Geochelone gigantea Schweigger) in three isolated populations was studied for 2 years on Aldabra Atoll. Density-dependent recruitment was demonstrated. Nest destruction in the low density area was dependent on the density of mature females providing a mechanism for regulating population size. Increases in annual rainfall and the resultant increase in food availability induced an increase in mean egg mass in the low density area (and thereby total hatchling production), whereas in the high density population mean clutch size, mean egg mass, total number of nests and total hatchling production all increased significantly. Large eggs produced large hatchlings which survived better during the first year than hatchlings from small eggs. Hatchling mortality was 94 and 81 % in the first year in the high and low density populations respectively. Recruitment into the 5 year age class (after which predation is considered negligible) had almost ceased in the high density population compared with 0.44 per 100 breeding females per year in the low density population.

Seasonal home range size and philopatry in two northern white-tailed deer populations

2000 ◽  
Vol 78 (11) ◽  
pp. 1930-1940 ◽  
Author(s):  
Louis Lesage ◽  
Michel Crête ◽  
Jean Huot ◽  
A Dumont ◽  
Jean-Pierre Ouellet
Keyword(s):  
Home Range Size ◽  
High Density ◽  
Home Ranges ◽  
Low Density ◽  
Adult Males ◽  
High Density Population ◽  
Wintering Areas ◽  
N 93 ◽  
Density Population ◽  
Competition For Resources

From 1994 to 1997, we compared summer and winter space utilisation by two white-tailed deer (Odocoileus virginianus) populations wintering in adjacent areas in southeastern Quebec characterised by deep snow cover. One population lived at low density (10 deer/km2) with access to abundant forage in winter (127 000 twigs/ha), whereas for the other, high-density population (20 deer/km2), forage availability was reduced (68 000 twigs/ha). Because of intraspecific competition for resources, we predicted that deer in the high-density population would have smaller home ranges, would exhibit greater philopatry, and would be more likely to disperse. Deer from both populations occupied summer home ranges that were similar in size (1182 ha for adult males; 1102 ha for adult females; 6033 ha for yearling males; 2528 ha for yearling females) but much larger than home ranges observed elsewhere in North America. The high-density population showed a higher level of philopatry than the low-density population during winter but not during summer. Most deer remained migratory during the study (n = 93) but 4 of the 5 that dispersed were from the high-density population. We speculate on the ability of white-tailed deer populations facing severe winters to adapt to using large home ranges in summer. Our results shed light on how wintering areas appear and expand.

scholarly journals A fencing experiment on a high-density population of Microtus townsendii

1977 ◽  
Vol 55 (7) ◽  
pp. 1166-1175 ◽  
Author(s):  
Rudy Boonstra ◽  
Charles J. Krebs
Keyword(s):  
Survival Rate ◽  
Breeding Season ◽  
Population Regulation ◽  
Control Area ◽  
High Density ◽  
Low Density ◽  
Vole Population ◽  
Sharp Decline ◽  
Density Population ◽  
Microtus Townsendii

If dispersal is prevented, a low-density vole population will increase to unusually high densities. A mouse-proof fence was constructed around a vole population that had already reached high density and both this population and one on a control area were live-trapped from January 1975 to November 1975. The population on the control remained at peak densities. The enclosed population increased to even higher density once the breeding season had started and had a higher survival rate than the control population. By midsummer the enclosed population had severely overgrazed the vegetation and went into a sharp decline. Dispersal losses from the control were estimated at 32% for males and 31% for females in these high-density populations. Microtus townsendii populations thus responded to a fence in a manner similar to that of other species that have been studied. This experiment indicates the importance of dispersal to population regulation in voles even at peak densities.

scholarly journals Anatomy and physiology of Cattail as related to different population densities

2015 ◽  
Vol 33 (1) ◽  
pp. 01-12 ◽  
Author(s):  
F.F. CORRÊA ◽  
R.H. MADAIL ◽  
S. BARBOSA ◽  
M.P. PEREIRA ◽  
E.M. CASTRO ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Density ◽  
Root Anatomy ◽  
Low Density ◽  
Typha Angustifolia ◽  
Anatomy And Physiology ◽  
Shoot Ratio ◽  
Root Shoot Ratio ◽  
Apoplastic Barriers ◽  
Density Population

The objective of this work was to evaluate the effects of the population density of Typha angustifolia plants in the anatomical and physiological characteristics. Plants were collected from populations of high density (over 50% of colonization capacity) and low density (less than 50% of colonization capacity) and cultivated under controlled greenhouse conditions. Plants from both populations were grown in plastic trays containing 4 L of nutritive solution for 60 days. At the end of this period, the relative growth rate, leaf area ratio, net assimilatory rate, root/shoot ratio, leaf anatomy, root anatomy, and catalase and ascorbate peroxidase activities were evaluated. Plants from high density populations showed increased growth rate and root/shoot ratio. Low density populations showed higher values of stomatal index and density in leaves, as well as increased palisade parenchyma thickness. Root epidermis and exodermis thickness as well as the aerenchyma proportion of high density populations were reduced, these plants also showed increased vascular cylinder proportion. Only catalase activity was modified between the high and low density populations, showing increased values in low density populations. Therefore, different Typha angustifolia plants show differences in its anatomy and physiology related to its origins on high and low density conditions. High density population plants shows increased growth capacity related to lower apoplastic barriers in root and this may be related to increased nutrient uptake capacity.

Life-support Training in High-density Population Centers

1978 ◽  
Vol 18 (11) ◽  
pp. 777-780
Author(s):  
WALTER F. PIZZI ◽  
MARTIN I. HASSNER ◽  
JANE E. ST. CLAIR ◽  
JAMES N. OSS
Keyword(s):  
Life Support ◽  
High Density ◽  
High Density Population ◽  
Density Population

Spacing of female kin in Columbian ground squirrels (Spermophilus columbianus)

1989 ◽  
Vol 67 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Wendy J. King
Keyword(s):  
Ground Squirrels ◽  
High Density ◽  
High Density Population ◽  
Spermophilus Columbianus ◽  
Close Relatives ◽  
Columbian Ground Squirrels ◽  
Density Population

The dispersion of matrilineally related females was examined within a high-density population of Columbian ground squirrels (Spermophilus columbianus) in southwestern Alberta. Females tended to nest near their natal site when no other female occupied it. Breeding females spaced themselves evenly so that close relatives formed intact groups but not dense clusters. The kin group was typically composed of a mother with one or two daughters that were nonlittermate sisters. Females appeared to be attracted to natal areas and the resources they contained, perhaps burrows.

Ranging behaviour of roe deer in an experimental high-density population: Are females territorial?

2012 ◽  
Vol 335 (12) ◽  
pp. 735-743 ◽  
Author(s):  
Marie-Line Maublanc ◽  
Eric Bideau ◽  
Romain Willemet ◽  
Clara Bardonnet ◽  
Georges Gonzalez ◽  
...  
Keyword(s):  
Roe Deer ◽  
High Density ◽  
High Density Population ◽  
Ranging Behaviour ◽  
Density Population
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