Population dynamics of three songbird species in a nestbox population in Central Europe show effects of density,climate and competitive interactions

Unravelling the contributions of density‐dependent and density‐independent factors in determining species population dynamics is a challenge, especially if the two factors interact. One approach is to apply stochastic population models to long‐term data, yet few studies have included interactions between density‐dependent and density‐independent factors, or explored more than one type of stochastic population model. However, both are important because model choice critically affects inference on population dynamics and stability. Here, we used a multiple models approach and applied log‐linear and non‐linear stochastic population models to time series (spanning 29 years) on the population growth rates of Blue Tits Cyanistes caeruleus, Great Tits Parus major and Pied Flycatchers Ficedula hypoleuca breeding in two nestbox populations in southern Germany. We focused on the roles of climate conditions and intra‐ and interspecific competition in determining population growth rates. Density dependence was evident in all populations. For Blue Tits in one population and for Great Tits in both populations, addition of a density‐independent factor improved model fit. At one location, Blue Tit population growth rate increased following warmer winters, whereas Great Tit population growth rates decreased following warmer springs. Importantly, Great Tit population growth rate also decreased following years of high Blue Tit abundance, but not vice versa. This finding is consistent with asymmetric interspecific competition and implies that competition could carry over to influence population dynamics. At the other location, Great Tit population growth rate decreased following years of high Pied Flycatcher abundance but only when Great Tit population numbers were low, illustrating that the roles of density‐dependent and density‐independent factors are not necessarily mutually exclusive. The dynamics of this Great Tit population, in contrast to the other populations, were unstable and chaotic, raising the question of whether interactions between density‐dependent and density‐independent factors play a role in determining the (in) stability of the dynamics of species populations.     

Pair bond and breeding success in Blue Tits Parus caeruleus and Great Tits Parus major

Data from 939 nests of the Blue Tit Parus caeruleus and 1008 nests of the Great Tit P. major from nestboxes provided in superabundance in mixed forest study sites between 1976 and 2001 were analysed to examine the effects of mate retention on breeding success and the relationship between mate fidelity and site fidelity. Most birds retained their former partner (76% in Great Tits and 65% in Blue Tits). The probability of a pair divorcing was affected by male age in Great Tits, divorce being more likely in pairs with first‐year males. Great Tit pairs breeding together for a second season bred earlier, but had no higher breeding success than pairs breeding together for the first time. In Blue Tits laying date and start of incubation tended to be earlier in pairs breeding together for a second season, but hatching and fledging dates were not earlier than in other pairs. Great Tit pairs breeding together for two consecutive seasons bred earlier in the second season than in the first, but breeding success did not differ significantly between years. In both species, breeding performance did not differ between pairs that divorced after a season and pairs that stayed together. Thus breeding success did not determine whether a pair divorced or bred together again. Neither Blue Tits nor Great Tits improved their breeding performance through divorce. Blue Tit females even had fewer fledglings in the year after divorce than in the year before. Mate retention affected breeding site fidelity. Blue Tit females had greater breeding dispersal distances between consecutive years when re‐mating than when breeding again with the same mate. In Great Tits both males and females dispersed more when re‐mating than when retaining the former partner, suggesting that mate retention increased the chance of retaining the breeding site. In both species, breeding dispersal distances did not differ between pairs that divorced and pairs in which one mate disappeared. Because no major advantage of mate retention was evident, we suggest that mate retention evolved under different conditions than those found in study sites with high breeding densities and a superabundance of artificial nesting sites.     

THERAPEUTIC STRATEGIES FOR THE INHIBITION OF INDUCIBLE NITRIC OXIDE SYNTHASE—POTENTIAL FOR A NOVEL CLASS OF ANTI-INFLAMMATORY AGENTS

In recent years, NO, a gas previously considered a potentially toxic chemical, has become established as a diffusible universal messenger mediating cell—cell communication throughout the body. In mammals, NO is a recognized mediator of blood vessel relaxation that helps to maintain blood pressure. In the central nervous system NO acts as a non-conventional neurotransmitter and participates in the establishment of long-term plasticity required for memory formation. In addition, NO is responsible for some parts of the host response to sepsis and inflammation and contributes to certain disease states. A number of strategies have emerged with regard to a pharmacological control of pathological NO overproductions. This review will discuss these novel therapeutic approaches that may provide new means for clinical medicine.     

Comparative morphology and functional interpretation of the sutures in the dermal skull roof of temnospondyl amphibians

Sutures in the dermal skull roof of several Palaeozoic temnospondyl amphibians were studied, including Archegosaurus decheni, Sclerocephalus haeuseri, Cheliderpeton latirostre (Archegosauridae), Acanthostomatops vorax (Zatrachydidae), Onchiodon labyrinthicus (Eryopidae), Micromelerpeton credneri and Branchierpeton amblystomum (Dissorophoidea). Lamellae, flat bevels, butt joints, steep walls, and grooves are the sutural types occurring. Morphological sutural differences cannot be used as taxonomically relevant characters, as they mainly differ in their functional manifestations. Similarities of sutural patterns in taxa not closely related are most probably based on convergence, therefore sutural morphology allows functional conclusions rather than revealing phylogenetic relationships. The basic sutural pattern is described in Micromelerpeton credneri. Different textures and obliquity patterns of the sutural surfaces are characteristic of each region of the skull roof. In all temnospondyls studied, the median plane and the margin of the skull roof show a nearly uniform sutural morphology; the circumorbital region is most complex. Although the skulls studied are akinetic, mesokinetic movements of dermal elements along their sutures must have been permitted to guarantee the dynamic stability of the skull construction.     

Detection of a new important staging and wintering area of the White Stork Ciconia ciconia by satellite tracking

Since 1991, a large-scale satellite tracking study of White Stork Ciconia ciconia has followed 75 individuals along the eastern migration route, which passes across Israel into eastern Africa. Twenty-six of these birds travelled at least as far as the Sudan. Fifteen (58%) did not migrate to the eastern Sudan — the primary winter quarters in Africa suggested by ring recoveries — but flew to western Sudan and Chad and in one case even through Cameroon and into Nigeria. The significance of this new, important staging region for White Storks should be investigated urgently to establish the areas that are ecologically valuable for the conservation of this species.     

Temporal genetic structuring of a specialist parasitoid,Lysiphlebus hirticornis Mackauer (Hymenoptera: Braconidae) attacking a specialist aphid on tansy

In insect species characterized by inbreeding, limited dispersal, and a metapopulation structure, high genetic differentiation and reduced genetic diversity within local populations are expected. Using the model system Lysiphlebus hirticornis Mackauer, a specialist parasitoid of the tansy aphid, Metopeurum fuscoviride Stroyan (Hemiptera: Aphididae), we examined within‐site temporal population dynamics and genetics, including molecular variation at the tansy plant level. Aphid‐parasitoid dynamics were surveyed and parasitoids sampled from 72 tansy plants at 11 sites in and around Jena, Germany, over one growing season. Thereafter, parasitoid samples were genotyped at 11 polymorphic microsatellite loci. Colonization, extinction, and recolonization events occurred during the season. Allele numbers and identities were highly variable over time. When samples from all sites were pooled, allele number over all loci showed a decreasing trend with time. At the level of sites, temporal changes in genetic diversity were more variable. Analysis of molecular variance revealed that samples at the plant level explained the highest variance compared to at site level. We conclude that the genetic structuring of this insect is very fine grained (i.e. at the tansy plant level) and the temporal genetic diversity is explained by a combination of extinction and recolonization events, as well as inbreeding. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 737–749.     

Gnathostomulida from Hawaii

As thc second in a series on Gnathostomulida from the Pacific Ocean this paper describes an additional eight species from Hawaii of which four are new to science. All are accommodated within existing genera: Haplognathia asymmetrica sp.n., Haplognathia ruberrima (Sterrer, 1966), Haplognathia rufa sp.n., Cosmognathia arcus Sterrer, 1991, Cosmognathia manubrium sp.n., Pterognathia ctenifera Sterrer, 1970, Pterognathia hawaiiensis sp.n., and Austrognathia novaeze landiae Sterrer, 1991.     

Ultrastructural Features of Three Ectocommensal Protozoa Attached to the Gills of the Red Swamp Crawfish,Procambarus clarkii (Crustacea: Decapoda)1

Because heavy branchial infestations are thought to interfere with respiration, we examined the attachment of three stalked ciliates commonly found in the branchial chambers of Louisiana crawfish. Attachments by Cothurnia sp., Epistylis sp. and Acineta sp. differ in their fine structure. Stalks of the peritrichous ciliates. Cothurnia and Epistylis, contain striated tubules that differ in their arrangement, diameter, and in the periodicity of their striations. In both species the striated tubules branch within the basal disk and attach to a pad of adhesive material secreted by the organism during initial attachment to the gill surface. The stalk of the suctorian Acineta is composed of a striated honeycomb-like matrix. Within the basal disc the matrix is disorganized; however, striated elements anchor the stalk to a pad of adhesive material. Attachment sites also differ in the amount of secretory material deposited. Cothurnia forms a multi-layered, granular pad; Epistylis forms an indistinct, microfibrillar layer, and Acineta deposits a thick mucoid pad. None of the ciliates appear to damage the gill epicuticle nor is there an obvious host response. Harmful effects are probably limited to a decrease in respiratory surface area and disruption of normal water flow patterns. This may impair respiration sufficiently to increase the susceptibility of crawfish to low dissolved oxygen concentrations encountered periodically in commercial crawfish ponds.     

Morphology and Morphogenesis of Strobilidium caudatum (Fromentel), Meseres corlissi N. Sp., Halteria grandinella (Müller), and Strombidium rehwaldi N. Sp., and a Proposed Phylogenetic System for Oligotrich Ciliates (Protozoa,Ciliophora)1

ABSTRACT. The morphology and morphogenesis of some oligotrichs were investigated using protargol impregnation, silver carbonate impregnation and scanning electron microscopy. The somatic kineties of Strobilidium caudatum form a spiral at the posterior pole. Strobilidiids without such a spiral are transferred to the genus Rimostrombidium. Fourteen new combinations and a nomen novum, Strobilidium kahli, are necessary, Meseres corlissi n. sp. is characterized by eight somatic kineties composed of long cilia which are not fused to “bristles” as they are in Halteria. Strombidium oblongum shows similar characteristics and is thus combined with Meseres. Strombidium rehwaldi n. sp. has an anterior and an equatorial girdle of extrusomes. The morphogenesis of Meseres and Halteria is very similar, i.e. the entire somatic ciliature and the oral primordium originate apokinetally on the cell surface; the parental somatic ciliature is resorbed. In strobilidiids and tintinnids, the oral anlagen develop in a subsurface pouch and the parental somatic kineties, which are not resorbed, elongate by intrakinetal proliferation of basal bodies. In strombidiids, the oral primordium develops in an intracellular sac or tube. These morphogenetic peculiarities and distinct morphologic characters (e.g. arrangement of adoral membranelles) were applied in constructing a phylogenetic system for oligotrichs using hypotrichs as outgroup. This shows that halteriids are more closely related to hypotrichs than they are to other oligotrichs. The Halteriidae are thus raised to ordinal and subclass ranks, Halteriida n. ord., Halteriia n. subcl.