Comparative demography of forest Peromyscus

1988 ◽  
Vol 66 (10) ◽  
pp. 2170-2176 ◽  
Author(s):  
David T. Krohne ◽  
Joseph F. Merritt ◽  
Stephen H. Vessey ◽  
Jerry O. Wolff
Keyword(s):  
Peromyscus Maniculatus ◽  
Deciduous Forest ◽  
Peromyscus Leucopus ◽  
Late Summer ◽  
The Other ◽  
Peak Density ◽  
Adult Females ◽  
Forest Sites ◽  
Comparative Demography ◽  
Breeding Seasons

The demography of Peromyscus leucopus and Peromyscus maniculatus was studied from 1979 to 1986 in four deciduous forest sites in Indiana, Virginia, Ohio, and Pennsylvania. In two sites (Virginia and Pennsylvania) the two species were sympatic; at the other two sites, Peromyscus leucopus was the only species present. Peak densities varied greatly among sites (range: Indiana Peromyscus leucopus peak = 30/ha; Pennsylvania Peromyscus maniculatus peak = 120/ha). Except for an apparent synchronous high in 1981, there was no strong temporal concordance of peaks or lows among sites. Breeding seasons were of comparable length at all four sites and typically showed a late summer (August–September) hiatus followed by some fall breeding. There was no consistent relationship among sites between over-winter survival and peak density the following summer or between the percentage of adult females pregnant and peak density. Thus, our data suggest that local processes are more important than regional ones in Peromyscus demography.

Breeding by Peromyscus in seasonal environments

1979 ◽  
Vol 57 (4) ◽  
pp. 719-727 ◽  
Author(s):  
John S. Millar ◽  
F. B. Wille ◽  
Stuart L. Iverson
Keyword(s):  
Breeding Season ◽  
Litter Size ◽  
Sexual Maturity ◽  
Peromyscus Maniculatus ◽  
Peromyscus Leucopus ◽  
Reproductive Rate ◽  
Reproductive Characteristics ◽  
Breeding Seasons

Reproductive characteristics of Peromyscus maniculatus in Manitoba and Peromyscus leucopus in Ontario were compared in order to determine the extent to which breeding compensates for relatively short breeding seasons. Peromyscus maniculatus had a shorter breeding season than P. leucopus, but frequency of litters, litter size, and age of females at sexual maturity were the same for both species. A comparison of breeding characteristics among Peromyscus from different geographic areas indicated that basic reproductive characteristics do not vary in relation to length of the breeding season.In general, we have no evidence that the basic reproductive characteristics of Peromyscus vary in relation to length of the breeding season. Peromyscus with short breeding seasons, on average, must have a lower annual reproductive rate than Peromyscus with long breeding seasons.

scholarly journals Observations on the biology of the pasture mealybug Balanococcus poae from Hawkes Bay pastures

2009 ◽  
Vol 62 ◽  
pp. 197-204
Author(s):  
J.G. Charles ◽  
A. Chhagan ◽  
S.A. Forgie ◽  
M.W.A. Slay ◽  
R.D. Edwards
Keyword(s):  
Late Summer ◽  
Soil Surface ◽  
Early Spring ◽  
Effective Control ◽  
Immature Stages ◽  
Morphometric Data ◽  
Peak Density ◽  
Single Generation ◽  
Potted Plants ◽  
Adult Females

The seasonal biology of Balanococcus poae was examined in Hawkes Bay from 2006 to 2008 Adult females were found throughout the year typically in wax cells ca 12 cm below the soil surface with a peak density of ca 1300/m2 during winter and early spring (JuneOctober) Winter eggs were followed by neonate nymphs from spring through summer The timing of lifestages indicates that there was a single generation each year but a partial second generation may also have occurred in late summer No males were found Morphometric data did not reliably separate different immature stages Neonate nymphs on potted plants crawled first to the tips of tillers and then moved down the blade to feed beneath the protective tiller sheath No parasitoids or predators of mealybugs were found In the absence of biological control grasses with endophytic fungi that confer resistance to pasture mealybug would give effective control

scholarly journals Comparative demography of the exotic Harmonia axyridis with other aphidophagous coccinellids reared on artificial diet

2014 ◽  
Vol 49 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Julianne Milléo ◽  
Francisco Sales Fernandes ◽  
Wesley Augusto Conde Godoy
Keyword(s):  
Life Table ◽  
Harmonia Axyridis ◽  
Reproductive Rate ◽  
The Other ◽  
Adult Longevity ◽  
Net Reproductive Rate ◽  
Anagasta Kuehniella ◽  
Survival Percentage ◽  
Comparative Demography ◽  
Biological Aspects

The objective of this work was to compare biological aspects and life table parameters of the coccinellids Harmonia axyridis, Cycloneda sanguineaand Hippodamia convergens. Insects were fed eggs of Anagasta kuehniella, and reared at 24.5±1ºC, 70±10% relative humidity, with a 12 hour photophase. Hippodamia convergenstook about 1.6 day to complete development, longer than H. axyridis, and 2.4 day longer than C. sanguinea.At immature stages, H. axyridisexhibited the highest survival percentage (49.2%), in comparison to the other coccinellids. For mean adult longevity, H. convergenswas deficient, in comparison with the other species. Mean period of pre oviposition was the longest in C. sanguinea; the longest oviposition time occurred for H. axyridis; and the post oviposition period was similar between the coccinellids. Considering the reproductive parameters, H. axyridisshowed the best performance in all aspects. For life table, the values of H. convergenswere higher than, although close, to those of H. axyridis. Nevertheless, the high net reproductive rate of H. axyridis showed this species potential to increase population size. The biological characteristics of the exotic H. axyridis favors its invasion and establishment in Brazil, corroborating results noticed in other countries.

The effect of exposure to conspecifics on restlessness in the parasitoid wasp Nasonia vitripennis (Hymenoptera: Pteromalidae)

2007 ◽  
Vol 139 (5) ◽  
pp. 678-684 ◽  
Author(s):  
B.H. King
Keyword(s):  
Habitat Quality ◽  
Parasitoid Wasp ◽  
Poor Quality ◽  
The Other ◽  
Dispersal Ability ◽  
Nasonia Vitripennis ◽  
Adult Females ◽  
Selection For ◽  
The Difference ◽  
Abundance And Distribution

AbstractWhen habitat quality is variable, there should be strong selection for the ability to detect and respond to the variation. Adult females of the parasitoid wasp Nasonia vitripennis (Walker) are known to increase their restlessness (the proportion of time in locomotion) both during and after exposure to a poor quality host. Doing so provides a mechanism for leaving a poor host and potentially finding a better host. This study examined whether restlessness also changes in response to competition as indicated by the presence of adult conspecifics. Both restlessness and the probability of dispersing across an inhospitable environment were greater when a female was with another female than when she was alone. However, restlessness did not remain elevated after the other female was removed. In contrast with females, restlessness of males did not increase either during or after exposure to other males, and the probability of dispersing across an inhospitable environment was unaffected by the presence of another male. The difference between females and males may be related to differences in dispersal ability and in the abundance and distribution of hosts versus mates.

scholarly journals XXIII.—On the Disruptive Discharge of Electricity: An Experimental Thesis for the Degree of Doctor of Science, Department A

1878 ◽  
Vol 28 (2) ◽  
pp. 633-671 ◽  
Author(s):  
Alexander Macfarlane
Keyword(s):  
Copper Wire ◽  
Late Summer ◽  
The Other ◽  
Straight Line ◽  
Summer Session ◽  
The Difference ◽  
A Chain ◽  
The One ◽  
Metallic Parts ◽  
The University

The experiments to which I shall refer were carried out in the physical laboratory of the University during the late summer session. I was ably assisted in conducting the experiments by three students of the laboratory,—Messrs H. A. Salvesen, G. M. Connor, and D. E. Stewart. The method which was used of measuring the difference of potential required to produce a disruptive discharge of electricity under given conditions, is that described in a paper communicated to the Royal Society of Edinburgh in 1876 in the names of Mr J. A. Paton, M. A., and myself, and was suggested to me by Professor Tait as a means of attacking the experimental problems mentioned below.The above sketch which I took of the apparatus in situ may facilitate tha description of the method. The receiver of an air-pump, having a rod capable of being moved air-tight up and down through the neck, was attached to one of the conductors of a Holtz machine in such a manner that the conductor of the machine and the rod formed one conducting system. Projecting from the bottom of the receiver was a short metallic rod, forming one conductor with the metallic parts of the air-pump, and by means of a chain with the uninsulated conductor of the Holtz machine. Brass balls and discs of various sizes were made to order, capable of being screwed on to the ends of the rods. On the table, and at a distance of about six feet from the receiver, was a stand supporting two insulated brass balls, the one fixed, the other having one degree of freedom, viz., of moving in a straight line in the plane of the table. The fixed insulated ball A was made one conductor with the insulated conductor of the Holtz and the rod of the receiver, by means of a copper wire insulated with gutta percha, having one end stuck firmly into a hole in the collar of the receiver, and having the other fitted in between the glass stem and the hollow in the ball, by which it fitted on to the stem tightly. A thin wire similarly fitted in between the ball B and its insulating stem connected the ball with the insulated half ring of a divided ring reflecting electrometer.

scholarly journals FEEDING AND REPRODUCTIVE ACTIVITY OF THE COPEPODS Drepanopus forcipatus AND Calanus australis DURING LATE SUMMER ON THE SOUTHERN PATAGONIAN SHELF (ARGENTINA, 47°-55°S)

2014 ◽  
Vol 62 (4) ◽  
pp. 295-314 ◽  
Author(s):  
Julieta Carolina Antacli ◽  
Marina E. Sabatini ◽  
Ricardo I. Silva ◽  
Daniel R. Hernández ◽  
Andrés J. Jaureguizar ◽  
...  
Keyword(s):  
Diet Composition ◽  
Feeding Activity ◽  
Food Pellet ◽  
Late Summer ◽  
Reproductive Activity ◽  
Seasonal Temperature ◽  
Patagonian Shelf ◽  
Adult Females ◽  
Female Reproductive Status ◽  
Potential Food

Drepanopus forcipatus and Calanus australis are key planktonic copepods on the southern Patagonian shelf. Their feeding and reproductive patterns and population status were investigated during late summer, when environmental conditions may be critical. The presence of food in the gut and food-pellet length were recorded in adult females and the most abundant copepodite stages. Diet composition was also studied in adult females. Female reproductive status was evaluated by gonad staging. Despite generally low feeding conditions and decreasing seasonal temperature, both copepods fed to some degree. The most numerous copepodites and adult females of both species showed similarly low feeding activity. About half of the adult females of the two species and C5s of C. australis contained food in their guts, but the proportion of fed C4-females of D. forcipatus was much lower. All copepods were generally feeding at low or intermediate levels. Gonad stage distribution and population structure showed low but still ongoing reproduction in both species. Gut content findings suggest a preference for smaller nanoplanktonic particles, especially dinoflagellates by D. forcipatus, and for autotrophic prey, particularly large diatoms by C. australis. The feeding and reproduction patterns of the two copepods were likely influenced by the distributions of potential food resources and temperature.

scholarly journals A comparison of bushfire fuel hazard assessors and assessment methods in dry sclerophyll forest near Sydney, Australia

2012 ◽  
Vol 21 (6) ◽  
pp. 755 ◽  
Author(s):  
Penny J. Watson ◽  
Sandra H. Penman ◽  
Ross A. Bradstock
Keyword(s):  
Hazard Assessment ◽  
Assessment Method ◽  
Assessment Methods ◽  
Urban Fringe ◽  
The Other ◽  
Fuel Load ◽  
Forest Sites ◽  
Sclerophyll Forest ◽  
Hazard Assessments ◽  
Sydney Australia

Over the last decade, fire managers in Australia have embraced the concept of ‘fuel hazard’, and guides for its assessment have been produced. The reliability of these new metrics, however, remains to be determined. This study compared fuel hazard ratings generated by five assessment teams using two Australian hazard assessment methods, in two dry sclerophyll forest sites on Sydney’s urban fringe. Attributes that underpin hazard scores, such as cover and height of various fuel layers, were also assessed. We found significant differences between teams on most variables, including hazard scores. These differences were more apparent when fuel hazard assessments focussed on individual fuel layers than when teams’ assessments were summarised into an overall fuel hazard score. Ratings of surface (litter) fuel hazard were higher when one assessment method was used than when assessors employed the other; however, ratings of elevated (shrub) and bark fuel hazard were relatively consistent across assessment methods. Fuel load estimates based on the two hazard assessment methods differed considerably, with differences between teams also significant. Inconsistency in scoring fuel hazard may lead to discrepancies in a range of management applications, which in turn may affect firefighting safety and effectiveness.

Effects of adults on survival and recruitment of Peromyscus leucopus

1987 ◽  
Vol 65 (10) ◽  
pp. 2519-2523
Author(s):  
Gregory H. Adler ◽  
Mark L. Wilson ◽  
Michael J. DeRosa
Keyword(s):  
Adult Female ◽  
Adult Male ◽  
Peromyscus Leucopus ◽  
Survival Rates ◽  
Adult Males ◽  
Control Grid ◽  
Young Males ◽  
Young Females ◽  
Breeding Seasons ◽  
And Control

A population of Peromyscus leucopus (white-footed mouse) in northeastern Massachusetts was manipulated for 3 years to determine the effects of adults on survival and recruitment. Two experimental grids were established, from which either all adult males or all adult females were removed continually. The effects of these two manipulations were compared with demography on a control grid. Manipulations had no apparent effect on breeding intensity of young, survival rates of adults, or residency rates of adults and young. Recruitment of adult males was higher on the adult male removal grid than on the control grid. Recruitment rates of adult males and of young males and young females were lower on the adult female removal grid than on the control grid. Survival rates of young males were higher on the adult female removal grid than on the control grid; this effect may have been due to either reduced adult female residency or adult male recruitment. All differences between experimental and control grids were noted only during breeding seasons. Adult males apparently limited recruitment of adult consexuals. The effects of manipulations on other measured parameters were inconclusive because of high immigration rates of adult males onto the adult male removal grid and reduced recruitment of adult males and decreased production of young on the adult female removal grid.

“Data for the Problem of Evolution in Man. V. On the Correlation between Duration of Life and the Number of Offspring”

1901 ◽  
Vol 35 (6) ◽  
pp. 458-479
Author(s):  
M. Beeton ◽  
G. U. Yule ◽  
Karl Pearson
Keyword(s):  
Natural Selection ◽  
Breeding Season ◽  
The Other ◽  
Similar Statement ◽  
Men And Women ◽  
Darwinian Theory ◽  
Theory Of Evolution ◽  
Biennial Plants ◽  
Long Life ◽  
Breeding Seasons

According to the Darwinian theory of evolution the members of a community less fitted to their environment are removed by death. But this process of natural selection would not permanently modify a race, if the members thus removed were able before death to propagate their species in average numbers. It then becomes an important question to ascertain how far duration of life is related to fertility. In the case of many insects death can interfere only with their single chance of offspring; they live or not for their one breeding season only. A similar statement holds good with regard to annual and biennial plants. In such cases there might still be a correlation between duration of life and fertility, but it would be of the indirect character, which we actually find in the case of men and women living beyond sixty years of age—a long life means better physique and better physique increased fertility. On the other hand, there is a direct correlation of fertility and duration of life in the case of those animals which generally survive a number of breeding seasons, and it is this correlation which we had at first in view when investigating the influence of duration of life on fertility in man. The discovery of the indirect factor in the correlation referred to above was therefore a point of much interest. For it seems to show that the physique fittest to survive is really the physique which is in itself (and independently of the duration of life) most fecund.

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