Search results for "prey"
showing 10 items of 117 documents
Upes nēģa Lampetra fluviatilis populāciju ģenētiskās daudzveidības izpēte ar mikrosatelītiem
2020
Šis bakalaura darbs ir turpinājums kursa darbam - “Kurzemes upēs sastopamo upes nēģu Lampetra fluviatilis mikrosatelītu genotipēšana”. Šis ir pirmais pētījums Latvijā par upes nēģa ģenētisko daudzveidību un populācijas ģenētisko struktūru Latvijas upēs, pamatojoties uz mikrosatelītu DNS variācijām. Darba mērķis bija novērtēt upes nēģa populācijas ģenētisko daudzveidību Latvijā. Iegūtie dati veicinās zināšanas par upes nēģu ģenētisko struktūru un palīdzēs izstrādāt ieteikumus ģenētisko resursu ilgtspējīgai apsaimniekošanai. No piecām upēm (Saka, Venta, Daugava, Salaca, Gauja) kopā tika ievākti 210 upes nēģa audu paraugi no muguras spurām, no kuriem tika izdalīta DNS. Genotipēšana tika veikta…
Social transmission in the wild can reduce predation pressure on novel prey signals
2021
Funder: Suomen Kulttuurirahasto (Finnish Cultural Foundation); doi: https://doi.org/10.13039/501100003125
The red tooth hypothesis: A computational model of predator-prey relations, protean escape behavior and sexual reproduction
2009
This paper presents an extension of the Red Queen Hypothesis (hereafter, RQH) that we call the Red Tooth Hypothesis (RTH). This hypothesis suggests that predator-prey relations may play a role in the maintenance of sexual reproduction in many higher animals. RTH is based on an interaction between learning on the part of predators and evolution on the part of prey. We present a simple predator-prey computer simulation that illustrates the effects of this interaction. This simulation suggests that the optimal escape strategy from the prey's standpoint would be to have a small number of highly reflexive, largely innate (and, therefore, very fast) escape patterns, but that would also be unlearn…
The predatory role of white shrimp (Litopenaeus setiferus) in seasonal declines of subtidal macrobenthos
2009
The overall purpose of this study was to develop a quantitative model to assess the influence of L. setiferus predation on subtidal macrobenthic abundance cycles in an estuarine creek system. Subtidal macrobenthic populations in temperate marine soft-bottom environments are known to undergo seasonal abundance cycles. Although the factors responsible for driving these seasonal shifts in abundance are difficult to identify, both environmental and biological factors have received credit. Juvenile white shrimp (Litopenaeus setiferus) are seasonally abundant epibenthic predators in the North Inlet estuary that have significant influence upon estuarine macrobenthic densities. Data generated from …
Eudontomyzon danfordi (Regan, 1911) Species Populations Ecological Status in Maramureş Mountains Nature Park (Romania)
2015
Abstract The Eudontomyzon danfordi characteristic habitats state of Maramureş Mountains Nature Park varies greatly, 19.05% are in excellent conservation status, 47.62% are in good/average status and 33.33% are in a partially degraded condition. The identified human impact categories which induced the decreasing of Eudontomyzon danfordi species habitat state in the studied area are: poaching, minor riverbeds morphodynamic changings, liquid and solid natural flow disruption, destruction of riparian trees and bush vegetation, habitat fragmentation-fish populations isolation, and organic/mining pollution activities.
Response of an arctic predator guild to collapsing lemming cycles
2012
6 pages; International audience; Alpine and arctic lemming populations appear to be highly sensitive to climate change, and when faced with warmer and shorter winters, their well-known high-amplitude population cycles may collapse. Being keystone species in tundra ecosystems, changed lemming dynamics may convey significant knock-on effects on trophically linked species. Here, we analyse long-term (1988-2010), community-wide monitoring data from two sites in high-arctic Greenland and document how a collapse in collared lemming cyclicity affects the population dynamics of the predator guild. Dramatic changes were observed in two highly specialized lemming predators: snowy owl and stoat. Follo…
Influence of fish aggregating devices (FADs) on anti-predator behaviour within experimental mesocosms
2015
Commercial fishers have used fish aggregating devices throughout the Mediterranean Sea for over 40 years. These devices attract numerous predatory and forage species in both coastal and offshore environments. This study examined the influence of fish aggregating devices on schooling and aggregating behaviour by small forage fish in quasi-natural mesocosms. Anti-predator behaviour was evaluated for juvenile Caranx crysos under a variety of treatment conditions. Results suggest that, in the absence of physical structure, C. crysos first respond to a predatory threat by forming a school. When a physical structure is present, however, C. crysos show an occasional tendency to aggregate near the …
Generalist invasion in a complex lake food web
2023
Invasive species constitute a threat not only to native populations but also to the structure and functioning of entire food webs. Despite being considered as a global problem, only a small number of studies have quantitatively predicted the food web-level consequences of invasions. Here, we use an allometric trophic network model parameterized using empirical data on species body masses and feeding interactions to predict the effects of a possible invasion of Amur sleeper (Perccottus glenii), on a well-studied lake ecosystem. We show that the modeled establishment of Amur sleeper decreased the biomasses o ftop predator fishes by about 10%–19%. These reductions were largely explained by inc…
Climate change and cyclic predator-prey population dynamics in the high Arctic.
2009
The high Arctic has the world's simplest terrestrial vertebrate predator–prey community, with the collared lemming being the single main prey of four predators, the snowy owl, the Arctic fox, the long-tailed skua, and the stoat. Using a 20-year-long time series of population densities for the five species and a dynamic model that has been previously parameterized for northeast Greenland, we analyzed the population and community level consequences of the ongoing and predicted climate change. Species' responses to climate change are complex, because in addition to the direct effects of climate change, which vary depending on species' life histories, species are also affected indirectly due to…
Effetti della cattività su alcuni parametri ematologici del grifone (Gyps fulvus)
2017
Haematological analysis is an essential field of veterinary medicine that provides inexpensive and reliable support to determinate animal health. The knowledge of how different factors affect the normal mean values of blood parameters is key to understand and improve animal health. In order to investigate how captivity can affect the haematological profile of birds of prey, the erythrocyte count, haemoglobin concentration, haematocrit, mean corpuscular volume, total leukocytes count of 123 griffon vultures (Gyps fulvus) were analysed. The birds were divided into 4 groups according to their life conditions: a control group of free-living griffons, 2 semi-captive groups held in an aviary for …