Search results for "Systematics"
showing 10 items of 6702 documents
Patterns in rotifer diapausing egg banks: Density and viability
2006
Here we present a quantitative study on the density, age and viability of the diapausing egg banks of the rotifer species complex Brachionus plicatilis in the sediments of 15 water bodies from Eastern Spain. Sampled ponds, located in coastal and inland areas, varied in salinity and ranged in size, depth and permanence. By identifying ‘hatched’, ‘deteriorated’ and ‘viable’ diapausing eggs in the sediment samples, we estimated production, hatching and deterioration in relation to the habitat properties of each pond. Our results indicate the presence of large numbers of diapausing eggs in the sediments of almost all of the ponds studied (2–115 eggs cm −2 ). Inland ponds tended to have higher d…
Description of Two New Species ofAnacharisDalman, 1823 (Hymenoptera: Figitidae, Anacharitinae) from the Afrotropical Region
2015
Two new species of Anacharis Dalman, 1823 from the Afrotropical Region are described: Anacharis afrotropica sp. n. and Anacharis rwenzori sp. n. Diagnostic characters and data about biology, distribution and affinities with other Anacharis species are given.
The acanthocephalan parasite Polymorphus minutus alters the geotactic and clinging behaviours of two sympatric amphipod hosts: the native Gammarus pu…
2005
Acanthocephala are parasites with complex life cycles involving arthropod intermediate hosts and vertebrate final hosts. They use predation as a means of transmission, and some species have developed the ability to modify behaviour of their intermediate hosts to enhance the probability of ingestion by the definitive host. Knowledge of how a single parasite species is adapted to modify the behaviour of different intermediate host species is important for the understanding of parasitic transmission in host communities. In Burgundy, the freshwater amphipod crustaceans Gammarus pulex (native species) and Gammarus roeseli (eastern European invader) are both intermediate hosts for the acanthoceph…
Bioelectronic monitoring of parasite-induced stress in brown trout and roach
1996
A non-contact bioelectronic monitoring system was used to record changes in heart rate, ventilation rate and swimming activity in brown trout Salmo trutta and roach Rutilus rutilus, following exposure to two species of cercariae of digenean trematodes: Diplostomum pseudospathaceum which is a common parasite in the lens of fishes and xiphidiocercariae of Plagiorchis elegans, a parasite of anatid birds, both of which have the snail Lymnaea stagnalis as their first intermediate host. Swimming activity increased significantly in roach exposed to Diplostomum cercariae at densities as low as 3.8l−1 and remained elevated for 24–36 h post exposure. Brown trout showed no response when exposed to low…
Limonium poimenum (Plumbaginaceae), a new chasmophyte species from Sicily
2014
Limonium poimenum is here proposed as a new species for Science. It is a very peculiar and extremely localized species, growing on a calcareous mountain of NW Sicily (southern Italy), where it grows on rupestrian places together with many other rare chasmophytic endemics. Iconography, morphological features, ecology and conservation status are provided, as well as a morphological comparison with L. todaroanum.
<p><strong>Towards resolving a problem of the identity of the <em>Aethus</em> species (Hemiptera: Heteroptera: Cydnidae) occu…
2014
The genus Aethus in Cambodia is known only from a single species collected in the 1950s that was originally identified as A. indicus. However, what was regarded as A. indicus in the Oriental and Australian regions appeared to consist of three sibling species, recognizable only on the basis of male genital structures, i.e., A. philippinensis, A. pseudindicus, and true A. indicus. To date, the lack of males representing this genus from Cambodia made it impossible to verify which species actually occur in this country. The present study, based on eight males collected at the same locality in Cambodia where the specimens were originally identified as A. indicus more than 50 years ago (i.e., Sie…
Evolutionary significance of the invasion of introduced populations into the native range of Meconopsis cambrica
2011
The long history of the deliberate or accidental and human-mediated dispersal of flowering plants has led to the introduction of foreign genotypes of many species into areas of Europe hitherto occupied by potentially distinct native populations. Studies of the genetic and evolutionary consequences of such changes are handicapped by the difficulty of identifying the surviving native populations of many species in the absence of clear morphological differences. We investigated the relationship between putative native and introduced populations of the herbaceous perennial Meconopsis cambrica (Papaveraceae), as the isolated native populations of this species can be identified by historical and …
WEASELS’ (MUSTELA NIVALIS NIVALIS) PREFERENCE FOR OLFACTORY CUES OF THE VOLE (CLETHRIONOMYS GLAREOLUS)
2003
Many studies on life history strategies of small mammals under predation risk are based on assumptions that mammalian predators use scent marking from prey in searching and hunting. This is especially true for small mustelids hunting in the tunnels and cavities of their prey. It is assumed that weasels use the estrous signs of female voles as hunting cues, which exposes such females to a more pronounced risk of predation. We studied the preferences of 57 least weasels (Mustela nivalis nivalis) toward odor cues from four different reproductive categories of the bank vole (Clethrionomys glareolus). In the first experiment, weasels selected clearly for vole odors over clean bedding in a Y-maze…
Temporal variation in reproductive allocation in a shield bug Elasmostethus interstinctus
1996
We investigated changes in the reproductive output and the effect of female phenotype on reproductive parameters in a shield bug Elasmostethus interstinctus (L.) (Heteroptera: Acanthosomatidae) over the whole reproductive period. At the beginning and the middle of the reproductive period eggs were smaller than at the end of the period. Clutch mass and number of eggs per clutch decreased in laying sequence, first clutches being much larger than any of the later ones. Lifetime fecundity correlated positively with female size: large females produced more eggs and lived longer than small ones. Egg size did not vary with female size. Offspring survival until adulthood increased with egg weight. …
Sex-specific transgenerational effects of early developmental conditions in a passerine
2007
Most studies dealing with the trade-off between offspring number and quality have overlooked the long-term consequences for the progeny. High investment in offspring number usually results in an increased competition among nest mates. The deterioration of the early developmental conditions, due to this increased competition, can impair individual quality over the long term, and subsequently affect survival and lifetime fecundity. Moreover, the consequences of the allocation rule to offspring number vs. quality can extend across generations and give raise to grandparental effects. These transgenerational trade-offs have been explored rarely. In the present study, we manipulated the breeding …