0000000000003965
AUTHOR
Marjo Pihlaja
showing 5 related works from this author
Food supplementation reveals constraints and adaptability of egg quality in the magpie Pica pica
2015
Differences in the deposition of limited maternal resources to eggs can reflect the optimal allocation to manipulate offspring phenotype, or constraints caused by maternal condition. We examined multiple maternal substances transferred to eggs in the magpie Pica pica to test the hypothesis that certain substances represent constraint and some optimal allocation. We did this by supplementary feeding magpies prior to egg-laying and then comparing the effect of food on maternal substances in conjunction with laying order relative to a control group. Certain substances such as carotenoids, immunoglobulins and avidin responded positively to food supplementation, whereas others, such as testoste…
Sex-specific differences in offspring personalities across the laying order in magpies Pica pica
2013
Maternal effects provide an important mechanism for mothers to create variation in offspring personality, and to potentially influence offspring life history strategies e.g. creating more/less dispersive phenotypes. However, within-clutch maternal effects often vary and hence there is potential for within-clutch variation in personality. We studied the effects of hatching order on explorative and neophobic behaviour of the magpies Pica pica in relation to sex using novel environment and novel object experiments. Hatching order did affect explorative behaviour in magpie, but did so in opposite directions for either sex. First-hatched females were more explorative and had a tendency to be les…
Maternal antibodies in a wild altricial bird: effects on offspring immunity, growth and survival
2006
1. In many animals immunity is not fully developed until adulthood but the young still need protection against various sets of pathogens. Thus, bird nestlings are highly dependent on antibodies received from their mother (in the eggs) during their rapid early growth period. The relationship between maternal immunity and the development of neonates' own immunity has been poorly studied. 2. It has been suggested that immune function plays an important part in mediating resource competition between different life-history traits, e.g. growth and reproduction. Maternal investment of antibodies has potentially permanent effects on offspring phenotype. Thus, the trade-offs between the immune funct…
Responses of boreal carabid beetle assemblages (Coleoptera, Carabidae) to clear-cutting and top-soil preparation
2006
Today, forestry is the most important disturbance force in Fennoscandian boreal forests, having remarkably altered fauna and flora in this biome. However, since the late 1900s, forest-management practices have been modified to better consider biodiversity while harvesting timber. For example, green-tree retention, gap felling, and lighter top-soil preparation methods (harrowing) have been introduced, but little is known about the ecological effects of these changes. We sampled carabid beetles in seven clear-cut stands that were subsequently harrowed. We studied the effects of (1) clear-cut size by comparing carabid catches of small gaps (ca. 0.16 ha) with those of larger clear-cuts (ca. 2 h…
Maternal effects in the magpie
2006
Marjo Pihlaja tutki väitöskirjatyössään äitivaikutusten merkitystä sopeumana vaihteleviin ympäristöoloihin käyttäen tutkimuslajina luonnonvaraisena pesiviä harakoita. Äitivaikutuksiin kuuluvat äidiltä jälkeläisille siirtyvät ympäristön äidille aiheuttamat ilmiasun piirteet sekä emon jakamien resurssien vaikutukset jälkeläisten ilmiasuun. Pihlaja tutki lintuja, mutta monet hänen tutkimansa mekanismit toimivat myös nisäkkäillä – siis myös ihmisillä.Pihlajan tavoitteena oli selvittää, peilaako munassa olevien yhdisteiden määrä vain emon kuntoa pesimäkauden alussa ja muninnan aikana, vai voiko näiden poikaselle tarjolla olevien yhdisteiden määrän vaihtelun takana olla myös evolutiivisesti merki…