Despite the ecological importance of pair bonding, the ontogeny of pair bond formation remains poorly understood. We capitalized on long-term high-resolution tracking of social interactions across ...replicated colonies of captive zebra finches, Taeniopygia guttata, to map the dynamics of social relationships prior to reproduction and to identify the role that relationship quality plays in subsequent reproductive performance. We found that pairs that developed stronger and more stable social relationships outside the breeding season were more likely to breed together and form a pair bond. Moreover, pairs that formed a stable social relationship initiated reproduction faster than those with less stable pair bonds, while the stability and the length of time since establishment of the pair bond both reduced the probability of divorcing. Our results demonstrate an important link between the ontogeny of social relationships and reproductive benefits that may explain the evolution of long-term monogamy.
•Pair bonding was characterized by stable and strong social relationships.•Pairs with stronger, more stable social relationships were more likely to breed.•Pair bonds with more stable social relationships initiated reproduction faster.•A stable social relationship was a key feature of long-term pair bonding.
Long-duration bonds and sovereign defaults Hatchondo, Juan Carlos; Martinez, Leonardo
Journal of international economics,
09/2009, Letnik:
79, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper extends the baseline framework used in recent quantitative studies of sovereign default by assuming that the government can borrow using long-duration bonds. This contrasts with previous ...studies, which assume the government can borrow using bonds that mature after one quarter. We show that, when we assume that the government issues bonds with a duration similar to the average duration of sovereign bonds in emerging economies, the model generates an interest rate that is substantially higher and more volatile than the one obtained assuming one-quarter bonds. This narrows the gap between the predictions of the model and the data, which indicates that the introduction of long-duration bonds may be a useful tool for future research about emerging economies. Our analysis is also relevant for the study of other credit markets.
Long-term social and genetic monogamy is rare in animals except birds, but even in birds it is infrequent and poorly understood. We investigated possible advantages of monogamy in a colonial, ...facultative cooperatively breeding bird from an arid, unpredictable environment, the sociable weaver (Philetairus socius). We documented divorce and extrapair paternity of 703 pairs over 10 years and separated effects of pair duration from breeding experience by analyzing longitudinal and cross-sectional datasets. Parts of the colonies were protected from nest predation, thereby limiting its stochastic and thus confounding effect on fitness measures. We found that 6.4% of sociable weaver pairs divorced and 2.2% of young were extrapair. Longer pair-bonds were associated with more clutches and fledglings per season and with reproducing earlier and later in the season, when snake predation is lower, but not with increased egg or fledgling mass or with nestling survival. Finally, the number of helpers at the nest increased with pair-bond duration. Results were similar for protected and unprotected nests. We suggest that long-term monogamy is associated with a better capacity for exploiting a temporally unpredictable environment and helps to form larger groups. These results can contribute to our understanding of why long-term monogamy is frequently associated with unpredictable environments and cooperation.
Sovereign default and maturity choice Sánchez, Juan M.; Sapriza, Horacio; Yurdagul, Emircan
Journal of monetary economics,
05/2018, Letnik:
95
Journal Article
Recenzirano
Odprti dostop
•Sovereign debt maturity and duration generally exceed a year and move pro-cyclically.•Yield spread curves are typically non-linear and upward-sloped, but may become non-monotonic and inverted near ...high-default risk episodes.•Output volatility, impatience, risk aversion and especially sudden stops are key determinants of maturity.•A default model where the sovereign chooses debt maturity rationalizes these stylized facts.
This study develops a novel model of endogenous sovereign debt maturity that rationalizes various stylized facts about debt maturity and the yield spread curve: first, sovereign debt duration and maturity generally exceed one year, and co-move positively with the business cycle. Second, sovereign yield spread curves are usually non-linear and upward-sloped, and may become non-monotonic and inverted during a period of high credit market stress, such as a default episode. Finally, output volatility, impatience, risk aversion, and especially sudden stops, are key determinants of maturity, both in our model and in the data.
1. For socially monogamous species, breeder bond dissolution has important consequences for population dynamics, but the extent to which extrinsic or intrinsic population factors causes pair ...dissolution remain poorly understood, especially among carnivores. 2. Using an extensive life-history data set, a survival analysis and competing risks framework, we examined the fate of 153 different wolf (Canis lupus) pairs in the recolonizing Scandinavian wolf population, during 14 winters of snow tracking and DNA monitoring. 3. Wolf pair dissolution was generally linked to a mortality event and was strongly affected by extrinsic (i.e. anthropogenic) causes. No divorce was observed, and among the pair dissolution where causes have been identified, death of one or both wolves was always involved. Median time from pair formation to pair dissolution was three consecutive winters (i.e. approximately 2 years). Pair dissolution was mostly human-related, primarily caused by legal control actions (36.7%), verified poaching (9.2%) and traffic-related causes (2.1%). Intrinsic factors, such as disease and age, accounted for only 7.7% of pair dissolutions. The remaining 44.3% of dissolution events were from unknown causes, but we argue that a large portion could be explained by an additional source of human-caused mortality, cryptic poaching. 4. Extrinsic population factors, such as variables describing the geographical location of the pair, had a stronger effect on risk of pair dissolution compared to anthropogenic landscape characteristics. Population intrinsic factors, such as the inbreeding coefficient of the male pair member, had a negative effect on pair bond duration. The mechanism behind this result remains unknown, but might be explained by lower survival of inbred males or more complex inbreeding effects mediated by behaviour. 5. Our study provides quantitative estimates of breeder bond duration in a social carnivore and highlights the effect of extrinsic (i.e. anthropogenic) and intrinsic factors (i.e. inbreeding) involved in wolf pair bond duration. Unlike the effects of intrinsic and extrinsic factors that are commonly reported on individual survival or population growth, here we provide quantitative estimates of their potential effect on the social unit of the population, the wolf pair.
This paper examines how shocks to government bond duration risk held by price‐sensitive investors affect the euro area term structure of interest rates and the wider macroeconomy. We construct a new ...measure of the bond “free float,” which adjusts total debt for foreign official holdings and weights by residual maturity. Using a small macrofinance Bayesian Vector Autoregression (VAR) model, we estimate that the first round of asset purchases under the European Central Bank's (ECB) public sector purchase program reduced euro area 10‐year bond yields by around 30 bps in 2015. The positive impact on the output gap and inflation in 2016 was about 0.2 and 0.3 ppt, respectively.
Early-life conditions may impact an individual’s ability to survive long enough to reach breeding age as well as its lifetime reproductive success (LRS). We examined how different aspects of parental ...quality and natal territory habitat were correlated with the probability of recruitment and subsequent LRS in a top avian predator. Using resight and banding data from a 30-year demographic study on Swainson’s Hawks (
Buteo swainsoni
), we first examined factors related to recruitment probability, followed by a secondary follow-up analysis we explored correlates of reproductive success, tracking the same individuals as they progress through major life stages. Our analysis tracks only individuals marked as nestlings and where both parents were also uniquely marked and known to the study. This marking requirement allowed us to examine mated pair characteristics while simultaneously separating the effects of parental experience by sex. Pair bond duration best explained recruitment and was positively correlated with the probability of offspring being recruited into the local breeding population. For individuals that survived the challenges of early life and recruited, a far smaller subset of individuals, we found that maternal experience best predicted an offspring’s quality, as expressed by LRS, receiving twice the support of other models. Surprisingly, while pair bond duration correlated with recruitment probability, it was not predictive of offspring LRS. These modeling steps mirror the progressive removal of frail individuals from the population, and reveal that different aspects predict success in advancing life stages. We hypothesize that more established pairs can successfully fledge lower quality offspring that recruit but subsequently have low lifetime reproductive success, while maternal effects have a large influence on offspring quality.
'This paper explores the optimal allocation of government bond purchases within a monetary union, using a two-region DSGE model, where regions are asymmetric with respect to economic size and ...portfolio characteristics: the extent of substitutability between assets of different maturity and origin, asset home bias, and steady-state levels of government debt. An optimal quantitative easing (QE) policy under commitment does not only reflect different region sizes but is also a function of these dimensions of portfolio heterogeneity. By calibrating the model to the euro area, we show that optimal QE favors purchases from the smaller region (Periphery instead of Core), given that the former faces stronger portfolio frictions. A fully optimal policy consisting of both the short-term interest rate and QE lifts the monetary union away from the zero lower bound faster than an optimal interest rate policy alone, which entails forward guidance'--Abstract, page ii.
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