Search results for "Animal Ecology"
showing 10 items of 120 documents
SIMULATING RANGE EXPANSION: MALE SPECIES RECOGNITION AND LOSS OF PREMATING ISOLATION IN DAMSELFLIES
2009
Prolonged periods of allopatry might result in loss of the ability to discriminate against other formerly sympatric species, and can lead to heterospecific matings and hybridization upon secondary contact. Loss of premating isolation during prolonged allopatry can operate in the opposite direction of reinforcement, but has until now been little explored. We investigated how premating isolation between two closely related damselfly species, Calopteryx splendens and C. virgo, might be affected by the expected future northward range expansion of C. splendens into the allopatric zone of C. virgo in northern Scandinavia. We simulated the expected secondary contact by presenting C. splendens fema…
Environment-mediated morph-linked immune and life-history responses in the aposematic wood tiger moth
2012
1. Warning signals are expected to evolve towards conspicuousness and monomorphism, and thereby hamper the evolution of multiple colour morphs. Here, we test fitness responses to different rearing densities to explain colour polymorphism in aposematic wood tiger moth (Parasemia plantaginis) males. 2. We used larval lines sired by white or yellow adult males selected for small or large melanization patterns of coloration. We reared these selected lines either solitarily (favourable conditions) or in aggregations (challenged conditions), and followed their performance to adult stage. We tested whether differences in larval density affected life-history traits, adult melanin expression, adult …
Calculating minimum discrepancy to assess the nestedness of species assemblages
2009
Nestedness is a pattern whereby species-poor assemblages are composed of subsets of the species occurring in richer assemblages. One of the most commonly used measures of the degree of nestedness for presence-absence matrices is the ‘discrepancy’ metric. A hitherto neglected property of that metric is that it may take several values for a given site-by-species matrix in the presence of ties in the marginal totals. This complicates the quantification of nestedness for the observed presence-absence matrix, as well as the assessment of statistical significance, which is typically achieved through Monte Carlo simulations. A solution to the problem is to calculate the minimum discrepancy using a…
Stable C and N isotope concentration in several tissues of the loggerhead sea turtle Caretta caretta from the western Mediterranean and dietary impli…
2007
CONCENTRACIÓN DE ISÓTOPOS ESTABLES DE C Y N EN VARIOS TEJIDOS DE LA TORTUGA BOBA CARETTA CARETTA DEL MEDITERRÁNEO OCCIDENTAL E IMPLICACIONES SOBRE LA DIETA. – La concentración isotópica de escudos del caparazón, piel, músculo y sangre de tortuga boba (Caretta caretta) fueron analizados para investigar el patrón de variación entre tejidos y para evaluar la posición de esta especie en las redes tróficas de la cuenca Argelina. La piel presentaba valores más altos de δ13C que el músculo o los escudos del caparazón y éstos presentaban valores más altos que la sangre. En cambio, el músculo presentaba valores más altos de δ15N que la piel, ésta valores más altos que la sangre y ésta valores más al…
Hadwenius tursionis (Marchi, 1873) n. comb. (Digenea, Campulidae) from the bottlenose dolphin Tursiops truncatus (Montagu, 1821) in the western Medit…
1994
The taxonomic position of Synthesium tursionis (Marchi, 1873) (Digenea, Campulidae) is revised, based on material from 147 worms from four bottlenose dolphins Tursiops truncatus stranded off the Comunidad Valenciana (Spanish western Mediterranean). The species is transferred to Hadwenius, as H. tursionis n. comb., and characterised by a high length/width ratio of the body, spinose cirrus and unarmed metraterm. Synthesium, a monotypic genus, becomes a synonym of Hadwenius. The intraspecific variation of some morphological traits is briefly discussed.
The origin of Swedish and Norwegian populations of the Eurasian harvest mouse (Micromys minutus).
2012
The harvest mouse (Micromys minutus) occurs throughout most of continental Europe. There are also two isolated and recently discovered populations on the Scandinavian peninsula, in Sweden and Norway. Here, we investigate the origin of these populations through analyses of mitochondrial DNA. We found that the two populations on the Scandinavian peninsula have different mtDNA haplotypes. A comparison of our haplotypes to published sequences from most of Europe showed that all Swedish and Norwegian haplotypes are most closely related to the haplotypes in harvest mice from Denmark. Hence, the two populations seem to represent independent colonisations but originate from the same geographical ar…
Contribution to the taxonomy of the family Campulidae Odhner, 1926 (Digenea) by means of a morphometric multivariate analysis
1996
Digeneans of the family Campulidae occur exclusively in marine mammals, particularly in cetaceans. Their taxonomy is confused, being based on adult morphology only. We used a multivariate discriminant analysis of morphometric data to provide new evidence on the taxonomy of the Campulidae. Measurements of 217 specimens from 21 species of all seven genera of the family were taken. The percentage of specimens correctly assigned into their own species was 96.3%. The first three discriminant functions accounted for most of the variation between the species, which were grouped together in suprageneric groups along the first and the second function. The ordination pattern observed conforms partly …
Redescription ofPhysaloptera brevivaginata Seurat, 1917 (Nematoda: Physalopteridae) from the batMyotis blythii (Tomes) (Chiroptera: Vespertilionidae)…
1995
Physaloptera brevivaginata Seurat, 1917 (Nematoda: Physalopteridae) is redescribed. Seurat's (1917) original description of this species was based on a single immature female. Detailed morphological study of several males, mature and, above all, immature females from the stomach of the lesser mouse-eared batMyotis blythii (Tomes) (Chiroptera: Vespertilionidae) in Spain, has elucidated many new morphological characters. This physalopterid species is distinguished from other closely-related species by the lengths of the body and spicules, the equatorial position of the vulva, the morphology of the female reproductive system and by a small conical process on the tail of mature females.M. blyth…
Extra-pair paternity and male characteristics in the pied flycatcher
1995
The pied flycatcher (Ficedula hypoleuca) is sexually dichromatic with extreme variation in male plumage coloration. The benefit for males of having black plumage is controversial, and few studies have found evidence for a sexual selection benefit of being black rather than brown. However, blacker males may be better able to achieve extra-pair fertilizations (EPFs), which may be an important component of sexual selection. We studied the role of EPFs in sexual selection in the pied flycatcher by establishing a set-up where two males with different back coloration (blacker vs browner) bred simultaneously near each other. DNA fingerprinting analysis revealed that 11% of offspring resulted from …
Studies on bucephalid digeneans parasitising molluscs and fishes in Finland I. Ecological data and experimental studies
1991
Two types of bucephalid cercariae are reported from the bivalve Anodonta anatina in two Finnish lakes. One, Type A, resembles in gross morphology the cercaria of Bucephalus polymorphus, and the other, Type B, resembles the cercaria of Rhipidocotyle campanula. Type A daughter-sporocysts develop more slowly, have a greater cercarial productivity and exhibit a differential diurnal rhythm to that of Type B. Cercariae of Type A have a shorter longevity than Type B and tend to encyst in the fins rather than the gill-arches of fish intermediate hosts. The main definitive host of Type A is pike Esox lucius and, in the case of Type B, perch Perca fluviatilis. Adults of Types A and B are morphologica…