Search results for "Nesting Behavior"
showing 10 items of 47 documents
Lack of APP and APLP2 in GABAergic Forebrain Neurons Impairs Synaptic Plasticity and Cognition.
2020
AbstractAmyloid-β precursor protein (APP) is central to the pathogenesis of Alzheimer’s disease, yet its physiological functions remain incompletely understood. Previous studies had indicated important synaptic functions of APP and the closely related homologue APLP2 in excitatory forebrain neurons for spine density, synaptic plasticity, and behavior. Here, we show that APP is also widely expressed in several interneuron subtypes, both in hippocampus and cortex. To address the functional role of APP in inhibitory neurons, we generated mice with a conditional APP/APLP2 double knockout (cDKO) in GABAergic forebrain neurons using DlxCre mice. These DlxCre cDKO mice exhibit cognitive deficits i…
Assessing the Cost of Mounting an Immune Response
2003
International audience; The evolution of parasite resistance has often been assumed to be governed by antagonistic selection pressures. Defense against pathogens, by mounting an immune response, confers evident benefits but may also incur costs, so that the optimal level of defense is expected to depend on the balance between benefits and costs. Although the benefits of immune surveillance are well known, estimates of costs are still equivocal. Here we studied the behavioral and physiological modifications associated with exposure to a onreplicating antigen (lipopolysaccharide [LPS] of Escherichia coli) in a passerine species, the house sparrow (Passer domesticus).We further investigated wh…
Flexible parental care: Uniparental incubation in biparentally incubating shorebirds
2017
The relative investment of females and males into parental care might depend on the population’s adult sex-ratio. For example, all else being equal, males should be the more caring sex if the sex-ratio is male biased. Whether such outcomes are evolutionary fixed (i.e. related to the species’ typical sex-ratio) or whether they arise through flexible responses of individuals to the current population sex-ratio remains unclear. Nevertheless, a flexible response might be limited by the evolutionary history of the species, because one sex may have lost the ability to care or because a single parent cannot successfully raise the brood. Here, we demonstrate that after the disappearance of one pare…
Correlates of lifetime reproductive success in three species of European ducks
2003
Number of breeding attempts is a strong correlate of lifetime reproductive success (LRS) in birds, but the relative importance of potentially interacting factors affecting LRS has rarely been fully evaluated. We considered simultaneously five main factors hypothesized to influence LRS (age at first breeding, nesting date, number of breeding attempts, female traits, brood parasitism) by analyzing with path analysis 22-year data sets for 1,279 individually marked females and their offspring in tufted duck ( Aythya fuligula), common pochard ( A. ferina) and northern shoveler (Anas clypeata). We recaptured marked offspring as breeding adults (n=496 females) and obtained more complete estimates …
Indirect cues of nest predation risk and avian reproductive decisions
2009
Current life-history theory predicts that increased mortality at early stages of life leads to reduced initial investment (e.g. clutch size) but increased subsequent investment during the reproduction attempt. In a field experiment, migratory pied flycatchers Ficedula hypoleuca perceived differences in mammalian nest predation risk and altered their reproductive strategies in two respects. First, birds avoided nest sites manipulated to reflect the presence of a predator. Second, birds breeding in risky areas nested 4 days earlier and laid 10 per cent larger clutches than those in safe areas, a result that runs counter to the prevailing life-history paradigm. We suggest that the overwhelmin…
Nest Site Selection by Kentish Plover Suggests a Trade-Off between Nest-Crypsis and Predator Detection Strategies
2014
Predation is one of the main causes of adult mortality and breeding failure for ground-nesting birds. Micro-habitat structure around nests plays a critical role in minimizing predation risk. Plovers nest in sites with little vegetation cover to maximize the incubating adult visibility, but many studies suggest a trade-off between nest-crypsis and predator detection strategies. However, this trade-off has not been explored in detail because methods used so far do not allow estimating the visibility with regards to critical factors such as slope or plant permeability to vision. Here, we tested the hypothesis that Kentish plovers select exposed sites according to a predator detection strategy,…
Predation as a landscape effect: the trading off by prey species between predation risks and protection benefits.
2007
1. Predators impose costs on their prey but may also provide benefits such as protection against other (e.g. nest) predators. The optimal breeding location in relation to the distance from a nesting raptor varies so as to minimize the sum of costs of adult and nest predation. We provide a conceptual model to account for variation in the relative predation risks and derive qualitative predictions for how different prey species should respond to the distance from goshawk Accipiter gentilis nests. 2. We test the model predictions using a comprehensive collection of data from northern Finland and central Norway. First, we carried out a series of experiments with artificial bird nests to test if…
Trade-offs between sexual advertisement and immune function in the pied flycatcher (Ficedula hypoleuca).
2004
Good genes models of sexual selection assume that sexual advertisement is costly and thus the level of advertisement honestly reveals heritable viability. Recently it has been suggested that an important cost of sexual advertisement might be impairment of the functioning of the immune system. In this field experiment we investigated the possible trade-offs between immune function and sexual advertisement by manipulating both mating effort and activity of immune defence in male pied flycatchers. Mating effort was increased in a non-arbitrary manner by removing females from mated males during nest building. Widowed males sustained higher haematocrit levels than control males and showed higher…
Rapid change in host use of the common cuckoo Cuculus canorus linked to climate change
2010
Parasites require synchrony with their hosts so if host timing changes with climate change, some parasites may decline and eventually go extinct. Residents and short-distance migrant hosts of the brood parasitic common cuckoo, Cuculus canorus , have advanced their phenology in response to climate change more than long-distance migrants, including the cuckoo itself. Because different parts of Europe show different degrees of climate change, we predicted that use of residents or short-distance migrants as hosts should have declined in areas with greater increase in spring temperature. Comparing relative frequency of parasitism of the two host categories in 23 European countries before and af…
No synergy needed: ecological constraints favor the evolution of eusociality.
2015
In eusocial species, some individuals sacrifice their own reproduction for the benefit of others. It has been argued that the evolution of sterile helpers in eusocial insects requires synergistic efficiency gains through cooperation that are uncommon in cooperatively breeding vertebrates and that this precludes a universal ecological explanation of social systems with alloparental care. In contrast, using a model that incorporates realistic ecological mechanisms of population regulation, we show here that constraints on independent breeding (through nest-site limitation and dispersal mortality) eliminate any need for synergistic efficiency gains: sterile helpers may evolve even if they are …