Landscape occupancy and local population size depends on host plant distribution in the butterfly Cupido minimus

2004 ◽  
Vol 120 (3) ◽  
pp. 355-361 ◽  
Author(s):  
Jochen Krauss ◽  
Ingolf Steffan-Dewenter ◽  
Teja Tscharntke
Keyword(s):  
Host Plant ◽  
Population Size ◽  
Local Population ◽  
Plant Distribution ◽  
Cupido Minimus

scholarly journals Orobanche purpurea on its newly discovered site near Zatoń Dolna (NW Poland): the problem of protection of a threatened parasitic plant species

2010 ◽  
Vol 17 (1) ◽  
pp. 33-38
Author(s):  
Bożena Prajs
Keyword(s):  
Host Plant ◽  
Population Size ◽  
Plant Species ◽  
Local Population ◽  
Parasitic Plant ◽  
Achillea Millefolium ◽  
Fallow Land ◽  
Growing Seasons ◽  
The Village ◽  
Nw Poland

Orobanche purpurea on its newly discovered site near Zatoń Dolna (NW Poland): the problem of protection of a threatened parasitic plant species A newly discovered local population of Orobanche purpurea in NW Poland is described. It was composed of 141 specimens when first found in 2007 on fallow land near the village of Zatoń Dolna. However, the size and distribution of this population changed considerably during the last three growing seasons. The remarkable decline in population size is probably due to competition of other species with the host plant, Achillea millefolium, and the effect of the parasite itself, which weakens its host.

scholarly journals Impact of human mobility on the periodicities and mechanisms underlying measles dynamics

2015 ◽  
Vol 12 (104) ◽  
pp. 20141317 ◽  
Author(s):  
Ramona Marguta ◽  
Andrea Parisi
Keyword(s):  
Population Size ◽  
Parallel Computation ◽  
Human Mobility ◽  
Local Population ◽  
Sir Model ◽  
Global Level ◽  
Radiation Model ◽  
Stochastic Fluctuations ◽  
Measles Outbreaks ◽  
Disease Free

Three main mechanisms determining the dynamics of measles have been described in the literature: invasion in disease-free lands leading to import-dependent outbreaks, switching between annual and biennial attractors driven by seasonality, and amplification of stochastic fluctuations close to the endemic equilibrium. Here, we study the importance of the three mechanisms using a detailed geographical description of human mobility. We perform individual-based simulations of an SIR model using a gridded description of human settlements on top of which we implement human mobility according to the radiation model. Parallel computation permits detailed simulations of large areas. Focusing our research on the British Isles, we show that human mobility has an impact on the periodicity of measles outbreaks. Depending on the level of mobility, we observe at the global level multi-annual, annual or biennial cycles. The periodicity observed globally, however, differs from the local epidemic cycles: different locations show different mechanisms at work depending on both population size and mobility. As a result, the periodicities observed locally depend on the interplay between the local population size and human mobility.

Adjustment of fecundity and sex ratio in response to social environments in a haplodiploid mite

2022 ◽  
Author(s):  
Nuwan Weerawansha ◽  
Qiao Wang ◽  
Xiong Zhao He
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Population Size ◽  
Local Population ◽  
Female Offspring ◽  
Social Environments ◽  
Positive Interaction ◽  
Offspring Sex Ratio ◽  
Offspring Sex ◽  
Large Populations

Animals can adjust reproductive strategies in favour of corporation or competition in response to local population size and density, the two key factors of social environments. However, previous studies usually focus on either population size or density but ignore their interactions. Using a haplodiploid spider mite, Tetranychus ludeni Zacher, we carried out a factorial experiment in the laboratory to examine how ovipositing females adjust their fecundity and offspring sex ratio during their early reproductive life under various population size and density. We reveal that females laid significantly more eggs with increasing population size and significantly fewer eggs with increasing population density. This suggests that large populations favour cooperation between individuals and dense populations increase competition. We demonstrate a significant negative interaction of population size and density that resulted in significantly fewer eggs laid in the large and dense populations. Furthermore, we show that females significantly skewed the offspring sex ratio towards female-biased in small populations to reduce the local mate competition among their sons. However, population density incurred no significant impact on offspring sex ratio, while the significant positive interaction of population size and density significantly increased the proportion of female offspring in the large and dense populations, which will minimise food or space competition as females usually disperse after mating at crowded conditions. These results also suggest that population density affecting sex allocation in T. ludeni is intercorrelated with population size. This study provides evidence that animals can manipulate their reproductive output and adjust offspring sex ratio in response to various social environments, and the interactions of different socio-environmental factors may play significant roles.

scholarly journals Seasonal changes in distribution and abundance of a local Corncrake population

2020 ◽  
Author(s):  
Michał Budka ◽  
Patryk Kokociński ◽  
Paweł Bogawski ◽  
Maciej Nowak ◽  
Joanna Teresa Białas ◽  
...  
Keyword(s):  
Population Size ◽  
Breeding Season ◽  
Site Fidelity ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Local Population ◽  
Bird Species ◽  
Adult Males ◽  
Habitat Conditions ◽  
Population Declines

Abstract Many bird species have experienced short- or long-term population declines. However, the mechanisms and reasons underlying such negative changes are often not fully understood, making it difficult to identify effective conservation measures to recover populations. In this study, we focused on local changes in the abundance and distribution of calling male Corncrakes Crex crex in relation to: (1) within- and between-season site fidelity of adult males, (2) spatial distribution of territories in consecutive years and (3) the effect of habitat conditions on population size. We counted the number of calling males at ten randomly selected study plots (1 km2) in 2014–2018. Additionally, males were caught and individually marked in years 2015–2017. We found significant between-year changes in Corncrake abundance, from a 34% decrease to a 21% increase. On average, 32% of males established territories in the same locations as males recorded in the previous year. Breeding site fidelity was very low, with only 2–5% of males recaptured in the following year. Males selected areas characterized by higher values of NDVI (Normalized Difference Vegetation Index–higher values indicate more biomass) than on average within the study area. Population size in a particular year was significantly affected by the NDVI of the previous year but not by the NDVI in the current breeding season. We suppose that Corncrakes may exhibit a nomadic breeding behavior, and settle at territories when they encounter optimal habitat conditions. Moreover, as population size was negatively correlated with habitat conditions at the beginning of the previous breeding season, we suppose that local population changes may reflect more general trends in a whole population rather than local breeding success. Therefore, we highlight the need for better knowledge of Corncrake dispersal within the main European population and for the coordination of monitoring and conservation efforts, especially in those regions where most Corncrakes breed.

scholarly journals Population structure and one-year dynamics of the endangered tropical tree species Caesalpinia echinata Lam. (Brazilian red-wood): the potential importance of small fragments for conservation

Rodriguésia ◽  
2009 ◽  
Vol 60 (1) ◽  
pp. 211-220 ◽  
Author(s):  
Pablo José Francisco Pena Rodrigues ◽  
Rodolfo Cesar Real de Abreu ◽  
Eduardo M. B. Barcellos ◽  
Haroldo Cavalcante de Lima ◽  
Fabio Rubio Scarano
Keyword(s):  
Size Structure ◽  
Local Population ◽  
Population Expansion ◽  
Plant Distribution ◽  
Matrix Analysis ◽  
Small Fragment ◽  
Potential Importance ◽  
One Year ◽  
Density And Biomass ◽  
Caesalpinia Echinata

ABSTRACT Caesalpinia echinata Lam. an endangered species, occurs in forest fragments of the Cabo Frio region, in Rio de Janeiro, Brazil. Data from four sub-populations were used to describe local population patterns and one-year dynamics. In each subpopulation, 0.1 ha-plots were set up and all C. echinata trees were mapped, and diameter and height were measured. The fragments sampled had different sizes and were subjected to various degrees of man-made disturbance, representing a succession gradient from an earlier (small fragment) to a later stage (large fragment). We compared the sub-populations as regards density, size structure, spatial distribution, germination and mortality, to identify short-term responses to mechanical injuries (broken stems, sand burial and man-made cuts). Matrix analysis considering the four C. echinata sub-populations together showed a slight tendency for population expansion (λ = 1.0211) if injury patterns do not lead to habitat extinction. On the other hand, sub-populations showed aggregated distribution patterns, particularly at forest edges. Diameter size structure varied from a reversed-J pattern, i.e. seedling abundance in the small fragment (more impacted sub-population) to a uniform plant distribution of size classes in the large one (less impacted sub-population). The sub-population in the smallest fragment showed the highest birth and mortality, in contrast to reduced demographic variation in the largest fragment. Moreover, the smallest fragment also showed the largest seedling stand density and biomass. These data indicate the potential importance of small fragments for the conservation of the Brazilian red-wood.

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