High frequency of extra-pair paternity in Swedish pied flycatchers revealed by allozyme electrophoresis and DNA fingerprinting

Summary We used two genetic techniques to study multiple parentage in the pied flycatcher (Ficedula hypoleuca). Allozyme electrophoresis of 131 nestlings from 22 clutches sampled in 1982 and 1987 showed that one nestling had a mismatched allele compared with its putative parents. In one additional nest the devitation from Mendelian inheritance of parental genotypes suggested extra-pair paternity. The calculated probability of detecting multiple paternity from the genetic variation at four loci was 0.115. The estimated population frequency of extra-pair fertilization (EPF) was 13%, based on two mismatches and the probability of detecting multiple paternity. The seven families (n = 38 nestlings) in the 1987 sample were also analyzed by DNA fingerprinting using the M13 and Jeffrey's 33.15 probes. Overall, 24% (n = 9) of the nestlings analyzed were genetically inconsistent with their putative father, with EPF occurring in three (43%) of the seven clutches. One nestling originated by intraspecific brood parasitism. Comparison of the two techniques using the same samples showed that allozyme electrophoresis has a resolution only 11% of that of DNA fingerprinting, close to the calculated probability of detecting multiple paternity (0.115). Both techniques suggest that extra-pair fertilization is relatively common in the Swedish populations investigated compared to the low frequency reported from a Norwegian population. Correspondence to: H.P. Gelter at the present address     

Comparative feeding ecology of felids in a neotropical rainforest

Summary Diet and habitat use of jaguar, puma, and ocelot, and populations of their mammalian prey, were studied in an undisturbed rainforest in southeastern Peru. Analysis of scats (feces) showed terrestrial mammals to be the chief prey of all three felids, but reptiles and birds were also numerically important in the diets of ocelot and jaguar. Prey diversity is high and the cats evidently take any readily captured vertebrate. For major terrestrial mammal prey of felids, density, biomass, prey/predator ratios, and annual offtake from the study area are estimated. All three cat species seem to hunt by opportunistic encounter of prey. Most mammalian prey species were taken in about the ratios of occurrence, but peccaries were taken by jaguar more often than expected. Most prey of jaguar have a body weight of >1 kg, those of ocelot, 1 kg. Jaguar often used waterside habitats, where they captured caiman and river turtles. Puma did not use these habitats or resources, although the puma prey sample was too small for much inference. The possible effects of felids on study area prey populations are discussed. Large and small cats partition prey at the body weight region where prey switches from low to high reproductive rates.     

Territoriality among male red-winged blackbirds

Summary To test theories recently proposed to explain territorial dominance in animals, we performed several versions of experiments in which male red-winged blackbirds were removed from their territories, held in captivity for varying periods, and then released to challenge their replacements. Males removed for 7 to 49 h recovered their territories from replacement males, either when released or over the following few days or weeks. The duration males were held off territory, the duration replacement males occupied territories, and the original owners' awareness before fighting that they had been replaced, apparently did not influence contest outcomes, but whether the new owner was a neighbor or a previously non-territorial male had some effect. The pattern of territory recovery observed most closely supports the hypothesis that territorial dominance in redwings arises from asymmetries in local knowledge and experience between owners and challengers, although another hypothesis, the Resource Holding Potential hypothesis, was not entirely ruled out. We discuss design of removal experiments to test territoral dominance, and propose that ecologies of particular species may powerfully influence outcomes of these experiments.     

Niche overlap in mud snails (hydrobiidae): freezing tolerance

Tolerance to freezing was measured in four species of hydrobiid snails exposed to temperatures from 0° to-8°C and salinities from 0 to 30 S four up to 7 d. Experiments showed the following increasing order of tolerance to freezing: Potamopyrgus jenkinsi (Smith), Hydrobia neglecta Muus, H. ulvae (Pennant) and H. ventrosa (Montagu). Survival decreased with increasing salinity in P. jenkinsi, while the opposite was found in Hydrobia species. H. ulvae survived only slightly better than H. neglecta, while H. ventrosa was very tolerant to freezing even at low salinities in contrast to the other species of Hydrobia. H. neglecta suffered higher winter mortality than H. ventrosa during the severe winter of 1985 in an estuary.     

Rate of growth and longevity of a large colony of Pentapora foliacea (Bryozoa) recorded in their oxygen isotope profiles

We studied the growth patterns and the stable oxygen isotopic composition of an individual of Pentapora foliacea (Ellis and Solander 1786) collected on October 6, 1978 from the Bristol Channel, Pembrokeshire, UK, Irish Sea. The stable oxygen isotopes are in equilibrium with the ambient seawater and show a marked seasonal variation reflecting seasonal water temperature changes. The stable oxygen isotopes further suggest that regular growth patterns of less calcified growth bands, which are secreted in winter, are perennial. These winter growth check lines can easily be used to determine longevity of these bryozoa colonies and of annual growth rates. The colony analysed is at least 3-years-old with an annual growth rate of approximately 2 cm per year.     

Binding of manganese by Antarctic Phaeocystis pouchetii and the role of bacteria in its release

The growth of Antarctic Phaeocystis pouchetii and associated bacteria in culture, and the binding and release of manganese were investigated using cultures derived from three clonal isolates collected from Prydz Bay, Antarctica, in November and December 1982. The cultured strains accumulated manganese from the culture medium. The concentration of Mn²⁺ in the alga was up to 58 times that of the medium. The Mn²⁺ apparently binds to the mucilage secreted by the cells and gives the alga its characteristic brown colour. Oxidation or complexing of Mn²⁺ by P. pouchetii was also indicated. Bacterial growth on the mucilage is inhibited in rapidly growing cultures by acrylic acid produced in the mucilage. Once the growth of P. pouchetii and production of ccrylic acid slow, bacterial numbers increase, leading to the solubilization of the mucilage and the release of Mn²⁺. In cool-temperate, subpolar and polar seas where P. pouchetii may form dense blooms, the binding and subsequent release of manganese may have important consequences for competing phytoplankton.     

Biomass assessment of estuarine macrophytobenthos using aerial photography

Traditional approaches for biomass assessment of estuarine macrophytes over vast areas are time consuming. A methodology for quick and accurate biomass estimation of macrophytes, growing at intertidal mudflats, has been developed and verified. Using a calculated relation between biomass and colour densities on the aerial photographs, biomass of macrophytes over a large area (ca 900 ha) could be assessed with an accuracy of about 10%. Biomass estimates could be partitioned over seagrasses, various green algae and brown algae.Communication No. 330 Delta Institute for Hydrobiological Research, Yerseke, The Netherlands     

Food and feeding habits of the king crab Paralithodes camtschatica near Kodiak Island,Alaska

Stomach contents from 809 king crabs, Paralithodes camtschatica (Tilesius), from 6 areas near Kodiak Island, Alaska, and 9 sampling periods (1978–1979) were exammed quantitatively; 713 (88%) contained food. Mollusca (mainly the bivalves Nuculana spp., Nucula tenuis, and Macoma spp.) and Crustacea (mainly barnacles) were the dominant food groups in terms of percentage wet weight and frequency of occurrence; fishes were the next most important group of prey. No significant differences in feeding between sexes occurred; however, significant differences were apparent in the quantity of food consumed from different sampling periods, areas, depths, size groups, and crab molt-classes. Consumption was greater in spring and summer and in offshore locations at depths of 126 to 150 m. In addition, king crabs <140 mm carapace length (CL) consumed more food than crabs 140 mm CL. Adult, newshell (individuals that molted during the last molting period) females greater than 95 mm CL, and newshell males greater than 100 mm CL, each contained more food than did juvenile, newshell females <120 mm CL.Contribution No. 449, Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99701, USA