Search results for "zoology"
showing 10 items of 4160 documents
Transparency reduces predator detection in mimetic clearwing butterflies
2019
International audience; Predation is an important selective pressure and some prey have evolved conspicuous warning signals that advertise unpalatability (i.e. aposematism) as an antipredator defence. Conspicuous colour patterns have been shown effective as warning signals, by promoting predator learning and memory. Unexpectedly, some butterfly species from the unpalatable tribe Ithomiini possess transparent wings, a feature rare on land but common in water, known to reduce predator detection.We tested if transparency of butterfly wings was associated with decreased detectability by predators, by comparing four butterfly species exhibiting different degrees of transparency, ranging from ful…
Weak warning signals can persist in the absence of gene flow
2019
Aposematic organisms couple conspicuous warning signals with a secondary defense to deter predators from attacking. Novel signals of aposematic prey are expected to be selected against due to positive frequency-dependent selection. How, then, can novel phenotypes persist after they arise, and why do so many aposematic species exhibit intrapopulation signal variability? Using a polytypic poison frog (Dendrobates tinctorius), we explored the forces of selection on variable aposematic signals using 2 phenotypically distinct (white, yellow) populations. Contrary to expectations, local phenotype was not always better protected compared to novel phenotypes in either population; in the white popul…
Short-term responses of Rana arvalis tadpoles to pH and predator stress: adaptive divergence in behavioural and physiological plasticity?
2022
Environmental stress is a major driver of ecological and evolutionary processes in nature. To cope with stress, organisms can adjust through phenotypic plasticity and/or adapt through genetic change. Here, we compared short-term behavioural (activity) and physiological (corticosterone levels, CORT) responses of Rana arvalis tadpoles from two divergent populations (acid origin, AOP, versus neutral origin, NOP) to acid and predator stress. Tadpoles were initially reared in benign conditions at pH 7 and then exposed to a combination of two pH (acid versus neutral) and two predator cue (predator cue versus no predator cue) treatments. We assessed behavioural activity within the first 15 min, an…
Lipid-related thiamine deficiency cause mortality of river lampreys (Lampetra fluviatilis) during pre-spawning fasting
2023
Publisher Copyright: © 2023 The Authors River lampreys (Lampetra fluviatilis) were caught in the fall 2014 on entering the River Perhonjoki for spawning and kept at a hatchery until spawning in late spring 2015 to produce larvae for compensatory stockings. Since the lampreys died massively from early February onwards, they were investigated in March and May to clarify the cause of the deaths. The symptoms in lampreys resembled those of lipid-related thiamine (vitamin B1) deficiency of salmonines, called the M74 syndrome in the Baltic Sea area. Because the lipid content of lampreys was known to be high, thiamine concentrations were analyzed in the liver and ovulated unfertilized eggs, and th…
Seeing red? Colour biases of foraging birds are context dependent.
2020
Funder: Suomen Kulttuurirahasto; doi: http://dx.doi.org/10.13039/501100003125
Application of a Split-Window Algorithm to Estimate Land Surface Temperature from NOAA-AVHRR Data
2006
Estimaciones de temperatura de la superficie terrestre, en días parciales a completamente despejados, fueron realizadas a partir de los datos proporcionados por el sensor Advanced Very High Resolution Radiometer (AVHRR), a bordo de la serie de satélites de la National Oceanic and Atmospheric Administration (NOAA) por aplicación de un algoritmo basado en el método de Split-Window. El algoritmo utilizado supone correcciones por emisividad y contenido de vapor de agua atmosférico, y fue validado con mediciones de temperatura de la superficie terrestre realizadas en terreno. Para esto, un data logger LI-1000 se instaló en la Estación Agrometeorológica dependiente del Instituto de Investigacione…
Importance of millipedes (Diplopoda) in the autumn-winter diet of Scolopax rusticola
2019
Authors examined the autumn-winter diet of the woodcock Scolopax rusticola from 407 gizzard samples originating from Crimea and Italy, resulting in a high number of millipedes (Diplopoda) in all the samples; this prey item was particularly important in terms of weight percentage. The authors consider that calcium, highly present in millipedes, should be an important source for the woodcocks’ metabolism during the autumn-winter seasons.
First report on the helminthfauna of the yellow-necked mouse, Apodemus flavicollis, in the Iberian Peninsula
2016
Summary Information about the prevalence of helminth parasites of the yellow-necked mouse, Apodemus flavicollis, in the Iberian Peninsula is almost non-existent and there is no reliable data reported from Spain. Fourteen A. flavicollis from the Erro River valley (Navarre, Spain) were examined for endoparasites, between February 2001 and July 2002. Thirteen specimens (92.9 %) of the total sample were parasitized by at least one of the following six helminth species: one trematode (Corrigia vitta), one cestode (Taenia parva larvae) and four nematodes (Trichuris muris, Calodium hepaticum, Heligmosomoides polygyrus and Syphacia stroma). This is the first report about the helminthfauna of A. fla…
Rearing background and exposure environment together explain higher survival of aquaculture fish during a bacterial outbreak
2019
1.Parasitic diseases represent one of the greatest challenges for aquaculture worldwide and there is an increasing emphasis on ecological solutions to prevent infections. One proposed solution is enriched rearing, where traditional stimulus‐poor rearing tanks are equipped with different types of structures to increase habitat complexity. Such spatial enrichment is known to increase survival of fish during parasite epidemics, but the underlying mechanisms are still unclear. 2.We studied whether enriched rearing affected infection of an important fish pathogen Flavobacterium columnare in young Atlantic salmon (Salmo salar) and sea‐migrating brown trout (Salmo trutta). First, we used natural b…
Phylogeny and evolution of parthenogenesis in Finnish bagworm moth species (Lepidoptera : Psychidae : Naryciinae) based on mtDNA-markers
2005
We investigated species diversity and evolution of parthenogenesis among bagworm moth species of Dahlica and Siederia using mitochondrial DNA sequencing. Parthenogenesis is rare among Lepidoptera other than Psychidae. Genera Dahlica and Siederia form a confusing group with controversial species boundaries and widely overlapping morphological features that make species determination difficult. We evaluated the reliability of species determination based on wing scale morphology by comparing it with a phylogenetic tree obtained using mtDNA. Species determination based on morphological characteristics did not correspond to species determination based on mtDNA markers. On the basis of the molecu…