Rafał Martyka

Kin recognition and adjustment of reproductive effort in zebra finches

The differential allocation theory predicts that females should invest more in offspring produced with attractive partners, and a number of studies support this prediction in birds. Females have been shown to increase reproductive investment when mated to males showing elaborated sexual traits. However, mate attractiveness might also depend on the interaction between male and female genotypes. Accordingly, females should invest more in offspring sired by individuals that are genetically dissimilar or carry superior alleles. Here, we show in zebra finches (Taeniopygia guttata) that pairs of unfamiliar genetic brothers and sisters are less likely to reproduce in comparison with randomly mated pairs. Among the brother–sister pairs, those that attempted to breed laid smaller clutches and of lower total clutch mass. Our results provide the first experimental evidence that females adjust their reproductive effort in response to the genetic similarity of their partners. Importantly, these results imply a female ability to assess relatedness of a social mate without prior association.

Winter Bird Assemblages in Rural and Urban Environments: A National Survey

Urban development has a marked effect on the ecological and behavioural traits of many living organisms, including birds. In this paper, we analysed differences in the numbers of wintering birds between rural and urban areas in Poland. We also analysed species richness and abundance in relation to longitude, latitude, human population size, and landscape structure. All these parameters were analysed using modern statistical techniques incorporating species detectability. We counted birds in 156 squares (0.25 km2 each) in December 2012 and again in January 2013 in locations in and around 26 urban areas across Poland (in each urban area we surveyed 3 squares and 3 squares in nearby rural areas). The influence of twelve potential environmental variables on species abundance and richness was assessed with Generalized Linear Mixed Models, Principal Components and Detrended Correspondence Analyses. Totals of 72 bird species and 89,710 individual birds were recorded in this study. On average (±SE) 13.3 ± 0.3 species and 288 ± 14 individuals were recorded in each square in each survey. A formal comparison of rural and urban areas revealed that 27 species had a significant preference; 17 to rural areas and 10 to urban areas. Moreover, overall abundance in urban areas was more than double that of rural areas. There was almost a complete separation of rural and urban bird communities. Significantly more birds and more bird species were recorded in January compared to December. We conclude that differences between rural and urban areas in terms of winter conditions and the availability of resources are reflected in different bird communities in the two environments.

An invasive gull displaces native waterbirds to breeding habitats more exposed to native predators

The effect of invasive opportunistic predators may include population changes in both native prey and native predators as well as alteration of predator–prey interactions. We analyzed the activity of native magpie Pica pica and changes in population, nest sites and nesting success probability of native waterbirds (namely: grebes, ducks, rails and native gulls) in response to the population growth of the invasive Caspian gull Larus cachinnans. The study was carried out at a reservoir in southern Poland and at a similar control reservoir where the Caspian gull was absent. Both the invasive gulls and the native magpie are opportunistic predators of nests of native waterbirds. The population increase of the invasive gull led to a decline in the population of native black-headed gulls Larus ridibundus only. However, the invasive gull displaced all the native species from the breeding islets located in the central part of the reservoir to islets located close to the shoreline. The latter were frequently visited by magpies, which depredated on nests along the shores, leading to an up to threefold decrease in nesting success as compared with nests located in the central area of the invaded reservoir. Predation by Caspian gulls was rarely observed. Thus, the invasion of Caspian gull caused complex direct and indirect effects on the waterbird community that included competition for breeding sites, changes in the spatial distribution of nests and alteration of predation rate by native predators. Moreover, the effects of invasion may not be reflected by changes in population size of native species.

Offspring survival is negatively related to maternal response to sheep red blood cells in zebra finches

The immune system is an important player in individual trade-offs, but what has rarely been explored is how different strategies of investment in immune response may affect reproductive decisions. We examined the relationship between the strength of maternal immune response and offspring viability and immune response in captive zebra finches Taeniopygia guttata. In three independent experiments, the females and subsequently their adult offspring were challenged with sheep red blood cells, and their responses were measured. There was no relationship between offspring immune response and that of their mothers. However, we found offspring survival until adulthood to be negatively related to maternal antibody titers. That effect was consistent among all experiments and apparent despite the fact that we partially cross-fostered newly hatched nestlings between nests of different females. This suggests that the observed effects of maternal immune response is not mediated by potentially altered female rearing abilities. To our knowledge, this is the first study showing the relationship between the strength of the immune response and between-generational fitness costs in birds.

Numerical and behavioural response of Black-headed Gull Chroicocephalus ridibundus on population growth of the expansive Caspian Gull Larus cachinnans

AbstractWe monitored population size from 1996 to 2003 and studied behavioural interactions (in 2001) between the native Black-headed Gull Chroicocephalus ridibundus and an expansive, opportunistic predator, the Caspian Gull Larus cachinnans, at water reservoirs in Poland. The expansive species caused a population decline in the native species and affected its choice of nest sites. The Black-headed Gulls perceived the risk of predation on the part of the larger Caspian Gulls. When both species occurred in close proximity, the native gull breeding pairs built nests where the vegetation was higher and its cover greater than at the sites chosen by pairs breeding far away from the expansive species. The native gulls in proximity to the expansive species spent more time guarding their nests. However, this was not compensatory, as egg losses were higher and breeding success much lower in pairs breeding near the Caspian Gulls than in those breeding far from the latter. Such a low breeding performance in the Black-headed Gulls was probably caused either by predation on the part of Caspian Gulls or by aggressive interactions among Black-headed Gulls. In fact, the rate of intraspecific aggression in native gulls was higher in pairs breeding in proximity to the expansive species than in those breeding far away from it. These intraspecific fights, caused by the presence of the expansive species were, at least partially, responsible for egg and chick losses. We did not find the presence of native gulls to have any effect on the behaviour and breeding performance of the expansive gull. These results indicate that the expansive predatory Caspian Gull negatively affects local population size and alters the behaviour of the native Black-headed Gull, and may, both directly and indirectly, affect its reproductive performance.ZusammenfassungAuswirkungen des Populationswachstums der expansiven WeißkopfmöweLarus cachinnansauf Populationsgröße und Verhalten der LachmöweChroicocephalus ridibundus Wir haben die Populationsgröße der Lachmöwe Chroicocephalus ridibundus an polnischen Stauseen zwischen 1996 und 2003 erfasst und im Jahr 2001 zusätzlich Verhaltensinteraktionen mit einem opportunistischen Räuber, der Weißkopfmöwe Larus cachinnans, untersucht. Die expansive Weißkopfmöwe verursachte einen Populationsrückgang der heimischen Lachmöwe und beeinflusste ihre Nistplatzwahl. Die Lachmöwen nahmen das Prädationsrisiko durch die größeren Weißkopfmöwen wahr. Wenn beide Arten in unmittelbarer Nähe zueinander vorkamen, bauten die Lachmöwenpaare ihre Nester in höherer Vegetation, wo sie besser versteckt waren, verglichen mit Paaren, die weiter entfernt von Weißkopfmöwen brüteten. In der Nähe der expansiven Art verbrachten die heimischen Möwen mehr Zeit damit, ihre Nester zu bewachen. Dennoch hatten Lachmöwenpaare, die in der Nähe von Weißkopfmöwen brüteten, höhere Eiverluste und einen deutlich niedrigeren Bruterfolg als Paare, die weiter entfernt brüteten. Eine derart niedrige Fortpflanzungsleistung der Lachmöwen war wahrscheinlich entweder auf Prädation durch Weißkopfmöwen oder auf aggressive Interaktionen zwischen Lachmöwen zurückzuführen. In der Tat war die intraspezifische Aggression der Lachmöwen höher bei Paaren, die in der Nähe von Weißkopfmöwen brüteten, als bei Paaren, die weiter entfernt brüteten. Diese durch die Anwesenheit der Weißkopfmöwe verursachten intraspezifischen Kämpfe waren zumindest zum Teil für Ei- und Kükenverluste verantwortlich. Wir fanden keine Hinweise darauf, dass die Anwesenheit der heimischen Möwen das Verhalten und die Fortpflanzungsleistung der expansiven Möwe beeinflusste. Diese Ergebnisse deuten darauf hin, dass die expansive räuberische Weißkopfmöwe die lokale Populationsgröße der heimischen Lachmöwe negativ beeinflusst, ihr Verhalten verändert und sowohl direkt als auch indirekt ihre Fortpflanzungsleistung beeinflussen kann.

Evolutionary interaction between W/Y chromosome and transposable elements

The W/Y chromosome is unique among chromosomes as it does not recombine in its mature form. The main side effect of cessation of recombination is evolutionary instability and degeneration of the W/Y chromosome, or frequent W/Y chromosome turnovers. Another important feature of W/Y chromosome degeneration is transposable element (TEs) accumulation. Transposon accumulation has been confirmed for all W/Y chromosomes that have been sequenced so far. Models of W/Y chromosome instability include the assemblage of deleterious mutations in protein coding genes, but do not include the influence of transposable elements that are accumulated gradually in the non-recombining genome. The multiple roles of genomic TEs, and the interactions between retrotransposons and genome defense proteins are currently being studied intensively. Small RNAs originating from retrotransposon transcripts appear to be, in some cases, the only mediators of W/Y chromosome function. Based on the review of the most recent publications, we present knowledge on W/Y evolution in relation to retrotransposable element accumulation.

The effect of pre-laying maternal immunization on offspring growth and immunity differs across experimentally altered postnatal rearing conditions in a wild songbird

BackgroundPrenatal antibody transfer is an immune-mediated maternal effect by which females can shape postnatal offspring resistance to pathogens and parasites. Maternal antibodies passed on to offspring provide primary protection to neonates against diverse pathogenic antigens, but they may also affect offspring growth and influence the development of an offspring’s own immune response. The effects of maternal antibodies on offspring performance commonly require that the disease environment experienced by a mother prior to breeding matches the environment encountered by her offspring after hatching/birth. However, other circumstances, like postnatal rearing conditions that affect offspring food availability, may also determine the effects of maternal antibodies on offspring growth and immunity. To date, knowledge about how prenatal immune-mediated maternal effects interact with various postnatal rearing conditions to affect offspring development and phenotype in wild bird population remains elusive. Here we experimentally studied the interactive effects of pre-laying maternal immunization with a bacterial antigen (lipopolysaccharide) and post-hatching rearing conditions, altered by brood size manipulation, on offspring growth and humoral immunity of wild great tits (Parus major).ResultsWe found that maternal immunization and brood size manipulation interactively affected the growth and specific humoral immune response of avian offspring. Among nestlings reared in enlarged broods, only those that originated from immunized mothers grew better and were heavier at fledging stage compared to those that originated from non-immunized mothers. In contrast, no such effects were observed among nestlings reared in non-manipulated (control) broods. Moreover, offspring of immunized females had a stronger humoral immune response to lipopolysaccharide during postnatal development than offspring of non-immunized females, but only when the nestling was reared in control broods.ConclusionsThis study demonstrates that offspring development and their ability to cope with pathogens after hatching are driven by mutual influences of pathogen-induced prenatal maternal effects and post-hatching rearing conditions. Our findings suggest that immune-mediated maternal effects may have context-dependent influences on offspring growth and immune function, related to the postnatal environmental conditions experienced by the progeny.

A biotrophic fungal infection of the great burnet Sanguisorba officinalis indirectly affects caterpillar performance of the endangered scarce large blue butterfly Phengaris teleius: Plant fungal infection and insect herbivore

Interactions between ecological communities of herbivores and microbes are commonly mediated by a shared plant. A tripartite interaction between a pathogenic fungus–host plant–herbivorous insect is an example of such mutual influences. In such a system a fungal pathogen commonly has a negative influence on the morphology and biochemistry of the host plant, with consequences for insect herbivore performance. Here we studied whether the biotrophic fungus Podosphaera ferruginea, attacking the great burnet Sanguisorba officinalis, affects caterpillar performance of the endangered scarce large blue butterfly Phengaris teleius. Our results showed that the pathogenic fungus affected the number and size of inflorescences produced by food‐plants and, more importantly, had indirect, plant‐mediated effects on the abundance, body mass and immune response of caterpillars. Specifically, we found the relationship between caterpillar abundance and variability in inflorescence size on a plant to be positive among healthy food‐plants, and negative among infected food‐plants. Caterpillars that fed on healthy food‐plants were smaller than those that fed on infected food‐plants in one studied season, while there was no such difference in the other season. We observed the relationship between caterpillar immune response and the proportion of infected great burnets within a habitat patch to be positive when caterpillars fed on healthy food‐plants, and negative when caterpillars fed on infected food‐plants. Our results suggest that this biotrophic fungal infection of the great burnet may impose a significant indirect influence on P. teleius caterpillar performance with potential consequences for the population dynamics and structure of this endangered butterfly.