Search results for "Aquarius"
showing 5 items of 5 documents
Does Population Density Determine the Mating Strategy in Males of the Water Strider Aquarius paludum?
2018
Mating behavior of a large Aquarius paludum paludum (Fabricius 1794) (Hemiptera: Gerridae: Gerrini) population was investigated on several field surveys during the mating season. Both types of mating behavior known for semi-aquatic true bugs were observed in the studied population: aggressive Type I mating for non-territorial males and unaggressive Type II mating for the territorial males. Some males establish individual territories at the lake shores that they defend for around one hour and switch to aggressive mating if they fail to attract a female to mate, while most males remain non-territorial. Radial 1–1.5 meter territories were aggressively defended from other males, conflicts being…
Geographical variation in wing polymorphism of the waterstrider Aquarius najas (Heteroptera, Gerridae)
1999
The waterstrider Aquarius najas is wingless in Northern Europe, while winged individuals occur frequently in Central and Southern Europe. To test if the latitudinal difference is genetically controlled, we collected mature individuals from 10 different populations and raised their offspring in ‘common garden’ laboratory conditions. Half of these populations were from southern and the other half from central Finland. Daylength and temperature do influence wing development among other species of waterstriders, and thus we maintained a similar short daylength and warm conditions for all populations. These conditions should be favourable for wing development in general. Among laboratory-bred in…
Global L-band vegetation volume fraction estimates for modeling vegetation optical depth
2021
The attenuation of microwave emissions through the canopy is quantified by the vegetation optical depth (VOD), which is related to the amount of water, the biomass and the structure of vegetation. To provide microwave-derived plant water estimates, one must account for biomass/structure contributions in order to extract the water component from the VOD. This study uses Aquarius scatterometer data to build an L-band global seasonality of vegetation volume fraction (d), representative of biomass/structure dynamics. The dynamic range of d is adapted for its application in a gravimetric moisture (Mg) retrieval model. Results show that d ranging from 0 to 3.35.10- 4 is needed for modelling physi…
Founder population size and number of source populations enhance colonization success in waterstriders.
2002
Understanding the factors that underlie colonization success is crucial both for ecological theory and conservation practices. The most effective way to assess colonization ability is to introduce experimentally different sets of individuals in empty patches of suitable habitat and to monitor the outcome. We translocated mated female waterstriders, Aquarius najas, into 90 streams that were not currently inhabited by the species. We manipulated sizes of propagules (from 2 to 16 mated females) and numbers of origin populations (one or two). Three origin populations were genetically different from each other, but they were less than 150 km from the streams of translocation. The results demonst…
Comparación de las temperaturas de brillo en Banda L proporcionadas por SMOS y Aquarius sobre distintas zonas de la Tierra
2017
En esta Tesis Doctoral se analizan datos procedentes de dos misiones espaciales de observación de la Tierra que han coincidido en el tiempo, SMOS (Soil Moisture Ocean Salinity), de la European Space Agency (ESA) y Aquarius, de la National Aeronautics and Space Administration (NASA). Estas misiones miden la temperatura de brillo de la Tierra en la banda L de microondas, entre otras variables geofísicas. Este trabajo se centra, fundamentalmente, en la comparación de este parámetro proporcionado por ambas misiones. Las diferentes resoluciones espaciales que proporcionan los sensores de ambos satélites hace difícil la comparación y esto ha motivado la aplicación de diferentes técnicas o métodos…