Search results for "classification"
showing 10 items of 29475 documents
Patterns of intermediate host use and levels of association between two conflicting manipulative parasites.
2002
For many parasites with complex life cycles, manipulation of intermediate host phenotypes is often regarded as an adaptation to increase the probability of successful transmission. This phenomenon creates opportunities for either synergistic or conflicting interests between different parasite species sharing the same intermediate host. When more than one manipulative parasite infect the same intermediate host, but differ in their definitive host, selection should favour the establishment of a negative association between these manipulators. Both Polymorphus minutus and Pomphorhynchus laevis exploit the amphipod Gammarus pulex as intermediate host but differ markedly in their final host, a f…
Parasitic outbreak of the copepod Balaenophilus manatorum in neonate loggerhead sea turtles (Caretta caretta) from a head-starting program
2017
Abstract Background Diseases associated to external parasitosis are scarcely reported in sea turtles. During the last decades several organism have been documented as a part of normal epibiont community connected to sea turtles. The copepod Balaenophilus manatorum has been cited as a part of epibiont fauna with some concern about its parasitic capacity. This study serves three purposes, i.e. (i) it sheds light on the type of life style that B. manatorum has developed with its hosts, particularly turtles; (ii) it makes a cautionary note of the potential health risks associated with B. manatorum in sea turtles under captivity conditions and in the wild, and (iii) it provides data on effective…
Within-season movements of Alpine songbird distributions are driven by fine-scale environmental characteristics
2020
AbstractInformation about distribution and habitat use of organisms is crucial for conservation. Bird distribution within the breeding season has been usually considered static, but this assumption has been questioned. Within-season movements may allow birds to track changes in habitat quality or to adjust site choice between subsequent breeding attempts. Such movements are especially likely in temperate mountains, given the substantial environmental heterogeneity and changes occurring during bird breeding season. We investigated the within-season movements of breeding songbirds in the European Alps in spring-summer 2018, using repeated point counts and dynamic occupancy models. For all the…
Cranial crassicaudiasis in two coastal dolphin species from South Africa is predominantly a disease of immature individuals.
2020
Crassicauda spp. (Nematoda) infest the cranial sinuses of several odontocetes, causing diagnostic trabecular osteolytic lesions. We examined skulls of 77 Indian Ocean humpback dolphins Sousa plumbea and 69 Indo-Pacific bottlenose dolphins Tursiops aduncus, caught in bather-protecting nets off KwaZulu-Natal (KZN) from 1970-2017, and skulls of 6 S. plumbea stranded along the southern Cape coast in South Africa from 1963-2002. Prevalence of cranial crassicaudiasis was evaluated according to sex and cranial maturity. Overall, prevalence in S. plumbea and T. aduncus taken off KZN was 13 and 31.9%, respectively. Parasitosis variably affected 1 or more cranial bones (frontal, pterygoid, maxillary …
Semen characteristics and their ability to predict sperm cryopreservation potential of Atlantic cod, Gadus morhua L.
2010
There is a lack of biomarkers or indices that can be used to predict the quality of fish semen samples following the freezing and thawing cycle. In the present study, a series of semen indices were tested to assess if they could accurately forecast the cryopreservation potential of Atlantic cod (Gadus morhua) semen. Fresh and frozen-thawed sperm activity variables were compared, and relationships between frozen-thawed sperm activity and fertilization success were examined. In comparison with fresh sperm, activity variables of frozen-thawed spermatozoa were reduced. Of the 18 males examined, mean (± SEM) spermatocrit of fresh sperm was 40.72 ± 4.23%, osmolality of the seminal plasma 366.32 ±…
A new species of Cypris (Crustacea: Ostracoda) from the Iberian Peninsula and the Balearic Islands, with comments on the first ostracod named using t…
2020
19 páginas, 9 figuras, 3 tablas.
World-wide variation in Drosophila melanogaster sex pheromone: behavioural effects, genetic bases and potential evolutionary consequences
1996
0016-6707 (Print) Journal Article Research Support, Non-U.S. Gov't; In Drosophila melanogaster, male wing vibration, a key element of courtship behaviour, is most efficiently induced by a female-specific contact pheromone cis, cis 7,11 heptacosadiene (7,11 HD), which is the main mature female cuticular hydrocarbon in the CS laboratory strain. A study of 63 strains from around the world revealed that flies from Sub-Saharan Africa and the Caribbean are unique in showing low levels 7,11 HD and high levels of the position isomer 5,9 HD. This difference maps to chromosome III, perhaps indicating a simple genetic control of the 7,11 HD:5,9 HD ratio. Females from strains with high levels of 7,11 H…
Variation in predation risk and vole feeding behaviour: a field test of the risk allocation hypothesis.
2003
Many prey animals experience temporal variation in the risk of predation and therefore face the problem of allocating their time between antipredator efforts and other activities like feeding and breeding. We investigated time allocation of prey animals that balanced predation risk and feeding opportunities. The predation risk allocation hypothesis predicts that animals should forage more in low- than in high-risk situations and that this difference should increase with an increasing attack ratio (i.e. difference between low- and high-risk situations) and proportion of time spent at high risk. To test these predictions we conducted a field test using bank voles ( Clethrionomys glareolus) as…
A survey of wild plant species for food use in Sicily (Italy) - results of a 3-year study in four Regional Parks
2016
Abstract Background This paper illustrates the results of a study carried out in four Regional Parks of Sicily (Italy), concerning traditional knowledge on food use of wild plant species. The main aims of the paper were: (i) to verify which wild plant species are used for food purpose in the local culture based on information provided by elderly inhabitants (ii) to verify the presence of wild plant species which have not been cited for food use in previous studies in the Mediterranean area (iii) to determine how many of the most frequently cited wild plant species are cultivated by the local population in the four Sicilian Parks. Methods Semi-structured interviews were carried out in the lo…
Transfer of individuals as a means of investigating natural selection in operation.
2009
Populations of Philaenus spumarius (Homoptera) displaying colour polymorphism at stable equilibrium were subjected to the introduction of alien phenotypes. In an exchange experiment between populations of isolated islands, 2/3 of population A, from Allgrundet, was transferred to Porskobben, and 2/3 of population P from Porskobben to Allgrundet. The immediate result of the transfer was A-type allele frequencies on Porskobben and P-type frequencies on Allgrundet. After four generations, the pre-transfer frequencies were almost completely restored. This change implies strong island-specific selection pressures. The process was remarkably rapid in view of the mixed composition of the gene pools…