Population dynamics and seasonal variation in the embryonic dormancy ofPilophorus gallicus(Hemiptera: Miridae): ‘don't put all your eggs in one basket'

2017 ◽  
Vol 20 (2) ◽  
pp. 191-200 ◽  
Author(s):  
Maria José Ramírez-Soria ◽  
Elena López-Gallego ◽  
Michelangelo La-Spina ◽  
Juan A. Sanchez
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Embryonic Dormancy

Population and Group Size of Cheer Pheasant Catreus Wallichii in Pokhari Valley, Garhwal Himalaya, India

2021 ◽  
Vol 9 (VII) ◽  
pp. 3503-3505
Author(s):  
Manish Kukreti
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Group Size ◽  
Monsoon Season ◽  
Garhwal Himalaya ◽  
Spring Season ◽  
Maximum Value ◽  
Minimum Group

Present paper reports population dynamics of Cheer pheasant Catreus wallichii in Pokhari valley, Garhwal Himalaya during January 2019 to December 2019. A total of 405 individuals with 145 groups were recorded. Overall individuals per sighting and group size (3.88±0.51 and 3.40±0.45) were also recorded during the study period respectively. Maximum value of individuals per sighting and group size were recorded in months of July and November (6.13±0.76 and 7.32±0.97), while minimum were recorded in May and April (1.75±0.27 and 1.17±0.26). Seasonal variation was also observed in population and group size. Maximum value of individual per sighting was recorded during the Monsoon season and minimum were recorded in spring season. While maximum and minimum group size were recorded in winter and spring Season.

scholarly journals Seasonal Variation in the Dietary Preferences of the Montane Vole, Microtus Montanus

1995 ◽  
Vol 19 ◽  
pp. 76-77
Author(s):  
Aeltia Pinter ◽  
Norman Negus ◽  
Patricia Berger
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Plant Species ◽  
Food Selection ◽  
Natural Populations ◽  
Food Preferences ◽  
Plant Resources ◽  
Microtus Montanus ◽  
Dietary Preferences ◽  
The One

Seasonal variation in food selection has been documented in several species on voles (Rothstein and Tamarin 1977, Cole and Batzli 1979 Goldberg et al. 1980) with considerable implications for winter survival and population dynamics. In Microtus Montanus a similar link may exist between growth, maturation, longevity, and population dynamics on the one hand and dietary composition on the other (e.g., Pinter and Negus 1965, Berger et al. 1981, Pinter 1988, Berger et al. 1992, Negus, Berger and Pinter 1992). Consequently, we undertook a study to investigate, in detail, the utilization of plant resources by the montane vole, Microtus montanus. The objectives of this project are twofold: (1) to identify the plant species that constitute the diet in natural populations of M. montanus and (2) to determine seasonal food preferences in relation to the availability of plant species and to the age, sex and cohorts of the montane vole.

scholarly journals A fish for all seasons: Spatial and temporal variation in patterns of demographic heterogeneity for Retropinna retropinna

2021 ◽  
Author(s):  
◽  
Christopher McDowall
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
New Zealand ◽  
Age Structure ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Environmental Variation ◽  
Life Cycles ◽  
Demographic Heterogeneity ◽  
Demographic Attributes

<p>Demographic heterogeneity can have big effects on population dynamics, but for most species we have limited understanding of how and why individuals vary. Variation among individuals is of particular importance for stage-structured populations, and/or where species have ‘complex life-cycles’. This is especially relevant in the case of amphidromous fishes that typically spawn in river mouths and estuaries, develop at sea and return to freshwater to finish development. These fish face strong selection pressures as they negotiate challenges around dispersal and development in order to reproduce successfully. Quantifying variation amongst individual fish can improve understanding of their population dynamics and suggest possible drivers of variation.  I evaluate patterns and sources of variation in demographic attributes of the New Zealand smelt (Retropinna retropinna). R. retropinna is an amphidromous fish that is endemic to New Zealand. While most populations have a sea-going larval stage, a number of landlocked freshwater populations occur, with the largest landlocked population residing in Lake Taupo. Here R. retropinna are presented with a variety of littoral feeding/spawning habitats and environmental conditions that may vary across distinct regions of the lake. In addition, the protracted spawning period for this species in Lake Taupo (occurring over eight months of the year) provides additional scope for seasonal variation to influence demographic attributes of individuals.  I sampled R. retropinna from discrete coastal habitats (beach or river) that were located in the eastern, southern and western regions of the lake. I evaluated patterns of variation in the size-structure, age-structure and morphology of R. retropinna among habitats and/or regions across Lake Taupo. I used otoliths to reconstruct demographic histories (ages, growth rates, hatch dates) of individuals, and used a set of statistical models to infer spatial variation in demographic histories. I found differences in size and age structure between regions, and a temporal effect of hatch date on larval/juvenile growth rates.  In addition, I obtained samples of R. retropinna from a sea-going population at the Hutt river mouth (sampled fish were presumed to be migrating upstream after their development period in Wellington Harbour and/or adjacent coastal environments). While Lake Taupo is large, deep, fresh, oligotrophic and strongly stratified for 8-9 months outside of winter, Wellington Harbour is less than a sixth of the area, shallow, saline, eutrophic and never stratified. These greatly differing environmental conditions led me to expect that these systems’ R. retropinna populations would carry significantly different demographic attributes. I compared the hatching phenology, recruitment age, body morphology, and individual growth histories (reconstructed from otoliths) of R. retropinna sampled from Lake Taupo and Wellington Harbour. I explored the relationships between demographic variation and environmental variation (water temperature, chlorophyll a) for the two systems and found that this additional environmental information could account for much of the seasonal variation in daily otolith increment widths of R. retropinna. My results also suggest that while the two sampled populations likely share similar hatching and spawning phenologies, individuals from Lake Taupo tend to grow more slowly, particularly during winter, and end up smaller than sea-going fish sampled near Wellington. I speculate that these differences reflect variation in food supply (zooplankton may be limited in Lake Taupo over winter).  Overall, my results demonstrate a high degree of variation in morphological and life-history traits within a single species, potentially driven by an interaction between environmental variation and timing of development. My work contributes to a growing body of literature on demographic heterogeneity, and may help to inform the management of landlocked populations of R. retropinna in Lake Taupo.</p>

scholarly journals Fecundity, body size and population dynamics of Chrysomya albiceps (Wiedemann, 1819) (Diptera: Calliphoridae)

2008 ◽  
Vol 68 (1) ◽  
pp. 123-128 ◽  
Author(s):  
TIS. Riback ◽  
WAC. Godoy
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Natural Populations ◽  
Wing Size ◽  
Chrysomya Albiceps ◽  
History Of ◽  
Positive Correlations ◽  
Temporal Trajectory ◽  
Tibia Length ◽  
Relative Constant

In this study, the seasonal variation of fecundity, wing and tibia length were investigated in natural populations of Chrysomya albiceps (Wiedemann, 1819) in an attempt to determine the changes in life history of the species as a function of seasonality. A relative constant temporal trajectory was found for fecundity, wing and tibia length over twenty-four months. Positive correlations between fecundity and wing size, fecundity and tibia size and wing and tibia sizes were observed. The implications of these results for population dynamics of C. albiceps are discussed.

scholarly journals The evolution of covert, silent infection as a parasite strategy

2009 ◽  
Vol 276 (1665) ◽  
pp. 2217-2226 ◽  
Author(s):  
Ian Sorrell ◽  
Andrew White ◽  
Amy B. Pedersen ◽  
Rosemary S. Hails ◽  
Mike Boots
Keyword(s):  
Infectious Disease ◽  
Population Dynamics ◽  
Seasonal Variation ◽  
Population Density ◽  
Host Population ◽  
Direct Link ◽  
Birth Rates ◽  
Transmission Rates ◽  
Transmission Success ◽  
Covert Infection

Many parasites and pathogens cause silent/covert infections in addition to the more obvious infectious disease-causing pathology. Here, we consider how assumptions concerning superinfection, protection and seasonal host birth and transmission rates affect the evolution of such covert infections as a parasite strategy. Regardless of whether there is vertical infection or effects on sterility, overt infection is always disadvantageous in relatively constant host populations unless it provides protection from superinfection. If covert infections are protective, all individuals will enter the covert stage if there is enough vertical transmission, and revert to overt infections after a ‘latent’ period (susceptible, exposed, infected epidemiology). Seasonal variation in transmission rates selects for non-protective covert infections in relatively long-lived hosts with low birth rates typical of many mammals. Variable host population density caused by seasonal birth rates may also select for covert transmission, but in this case it is most likely in short-lived fecund hosts. The covert infections of some insects may therefore be explained by their outbreak population dynamics. However, our models consistently predict proportions of covert infection, which are lower than some of those observed in nature. Higher proportions of covert infection may occur if there is a direct link between covert infection and overt transmission success, the covert infection is protective or the covert state is the result of suppression by the host. Relatively low proportions of covert transmission may, however, be explained as a parasite strategy when transmission opportunities vary.

scholarly journals Seasonal Variation in Population Dynamics of Helminth Parasites in Clarias batrachus from Natural wetlands of Sylhet, Bangladesh

2016 ◽  
Vol 5 (2) ◽  
pp. 86-89
Author(s):  
SM Bari ◽  
SMI Khalil ◽  
MAA Mamun ◽  
MJ Islam ◽  
MA Baten ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Seasonal Variation ◽  
Clarias Batrachus ◽  
Eastern Region ◽  
Helminth Parasites ◽  
Post Monsoon ◽  
Four Seasons ◽  
Field Investigations ◽  
North Eastern ◽  
Natural Wetlands

A year round field investigations were conducted with the aim to examine the seasonal variation in population dynamics of helminth parasites in Clarias batrachus from different natural aquatic habitat of north-eastern region of Bangladesh, Sylhet. This article summarizes the percentage of prevalence, mean intensity, abundance and index of infestation of helminth parasites in the C. batrachus during different months and seasons of the year in accordance with temperature, humidity and rainfall. The investigation period were categorized into four seasons i.e. pre-monsoon (February-April), monsoon (May-July), post-monsoon (August- October) and winter (November- January). A total 180 C. batrachus host individuals were examined and among them 139 (67.87%) specimens were found to be infested with 2205 individuals of parasites of three different groups namely trematode, cestode and nematode. Almost (100%) prevalence of helminth infestation were recorded from both male and female C. batrachus during the winter (Nov-Jan), followed by (Feb-April) pre-monsoon (66.67-86.67%) and (Aug-Sep) post-monsoon (66.67-80.00%) while lowest (53.33-60.00%) in monsoon or rainy season (May-July). Lower range of environmental temperature (21.05–25.050C), associated with moderate humidity (62.00-64.00%) and scarcity of rainfall increases the intensity of helminthes parasitic infestation in C. batrachus. In consistent to this, with the gradual increasing in ambient temperature (28.01- 30.010C) and humidity (75.00-89.00%) associated with moderate rainfall (33.40-790.90 mm) declining the intensity of helminthes infestation in C. batrachus of the study area.International Journal of Natural Sciences (2015), 5(2) 86-89

Seasonal variation in the population growth rate of a dominant zooplankter: what determines its population dynamics?

2013 ◽  
Vol 58 (6) ◽  
pp. 1221-1233 ◽  
Author(s):  
Raquel Jiménez-Melero ◽  
José M. Ramírez ◽  
Francisco Guerrero
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Seasonal Variation ◽  
Population Growth ◽  
Population Growth Rate
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