Search results for "spring"
showing 10 items of 600 documents
Direct and transgenerational effects of an experimental heat wave on early life stages in a freshwater snail
2018
AbstractGlobal climate change imposes a serious threat to natural populations of many species. Estimates of the effects of climate change-mediated environmental stresses are, however, often based only on their direct effects on organisms, and neglect the potential transgenerational effects. We investigated whether high temperature (i.e. an experimental heat wave) that is known to reduce performance of adultLymnaea stagnalissnails affects their offspring through maternal effects. Specifically, we tested whether eggs and hatched juveniles are affected by maternal thermal environment, and how strong these effects are compared with direct effects of temperature on offspring. We examined the eff…
Parental allocation of additional food to own health and offspring growth in a variable environment
2009
Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study sys- tem, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls (Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 (an increase phase) and 2003 (a decrease phase), and measured offspring growth…
A head start for life history development? Family income mediates associations between height and immune response in men.
2018
OBJECTIVES Male height and health affect a diverse range of social and economic outcomes such as competition for resources and mates. Life history theory predicts that limited availability of bioenergetic resources curbs the development of central life history functions such as somatic growth, immunity, and investment in offspring. Although genetic factors are important determinants of height, other factors such as income level may affect the incidence of infections during ontogeny, thus having indirect effects on somatic growth. We tested whether growing up in families with a higher income positively affects height and immune function. MATERIALS AND METHODS Seventy-three young Latvian men …
Manipulating Individual Decisions and Environmental Conditions Reveal Individual Quality in Decision-Making and Non-Lethal Costs of Predation Risk
2012
Received: July 6, 2012; Accepted: November 13, 2012; Published: December 13, 2012
Resource availability and goshawk offspring sex ratio variation: a large-scale ecological phenomenon
2002
Summary 1. Local population studies have shown that sex allocation among many birds and mammals seems to be partly non-random and in connection to surrounding factors, such as environmental or parental quality. In this scenario, if environmental quality varies in space and time, it is feasible that environmental quality also comes to influence offspring sex ratio on larger geographical scales. 2. Investigating this idea - using nation-wide data sets on size-dimorphic Finnish northern goshawks Accipiter gentilis from 1989 to 1998 - we found that offspring sex ratio is related to spatial and temporal variation in availability of their main prey, woodland grouse species. 3. In a majority of lo…
Phenological sensitivity to climate change is higher in resident than in migrant bird populations among European cavity breeders
2018
Many organisms adjust their reproductive phenology in response to climate change, but phenological sensitivity to temperature may vary between species. For example, resident and migratory birds have vastly different annual cycles, which can cause differential temperature sensitivity at the breeding grounds, and may affect competitive dynamics. Currently, however, adjustment to climate change in resident and migratory birds have been studied separately or at relatively small geographical scales with varying time series durations and methodologies. Here, we studied differential effects of temperature on resident and migratory birds using the mean egg laying initiation dates from 10 European n…
The Impact of Variations in the Climate on Seasonal Dynamics of Phytoplankton
2009
Phytoplankton, an assemblage of suspended, primarily autotrophic single cells and colonies, forms part of the base of the pelagic food chain in lakes. The responses of phytoplankton to anthropogenic pressures frequently provide the most visible indication of a long-term change in water quality. Several attributes related to the growth and composition of phytoplankton, such as their community structure, abundance as well as the frequency and the intensity of blooms, are included as indicators of water quality in the Water Framework Directive. The growth and seasonal succession of phytoplankton is regulated by a variety of external as well as internal factors (Reynolds et al., 1993; Reynolds,…
Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil
2018
It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this …
Temporal variability in offspring quality and individual reproductive output in a broadcast-spawning marine fish
2017
Abstract The protracted spawning period of broadcast-spawning marine fishes has potential to generate considerable variability in metrics of individual reproductive output. We undertook a temporally detailed genetic study of larvae produced by Atlantic cod (Gadus morhua) from two spatially proximate populations spawning under controlled semi-natural conditions over 94 days. Based on daily samples of larvae (n = 4489 in total), we document fine-scaled temporal changes in, and correlates of, offspring phenotype and reproductive output (egg batches produced or fertilized). Larval length and standardized yolk-sac volume declined 11 and 49% over the spawning period, respectively. The adaptive si…
Maternal effects in quail and zebra finches: behavior and hormones.
2013
8 pages; International audience; Maternal effects are influences of parents on offspring phenotype occurring through pathways other than inherited DNA. In birds, two important routes for such transmission are parental behavior and non-DNA egg constituents such as yolk hormones. Offspring traits subject to parental effects include behavior and endocrine function. Research from the Adkins-Regan lab has used three avian species to investigate maternal effects related to hormones and behavior. Experiments with chickens and Japanese quail have shown that maternal sex steroids can influence sex determination to produce biased offspring sex ratios. Because all birds have a ZZ/ZW chromosomal sex de…