Long-term stress levels are synchronized in dogs and their owners

This study reveals, for the first time, an interspecific synchronization in long-term stress levels. Previously, acute stress, has been shown to be highly contagious both among humans and between individuals of other species. Here, long-term stress synchronization in dogs and their owners was investigated. We studied 58 dog-human dyads and analyzed their hair cortisol concentrations (HCC) at two separate occasions, reflecting levels during previous summer and winter months. The personality traits of both dogs and their owners were determined through owner-completed Dog Personality Questionnaire (DPQ) and human Big Five Inventory (BFI) surveys. In addition, the dogs’ activity levels were continuously monitored with a remote cloud-based activity collar for one week. Shetland sheepdogs (N = 33) and border collies (N = 25), balanced for sex, participated, and both pet dogs and actively competing dogs (agility and obedience) were included to represent different lifestyles. The results showed significant interspecies correlations in long-term stress where human HCC from both summer and winter samplings correlated strongly with dog HCC (summer: N = 57, χ2 = 23.697, P < 0.001, β = 0.235; winter: N = 55, χ2 = 13.796, P < 0.001, β = 0.027). Interestingly, the dogs’ activity levels did not affect HCC, nor did the amount of training sessions per week, showing that the HCC levels were not related to general physical activity. Additionally, there was a seasonal effect in HCC. However, although dogs’ personalities had little effects on their HCC, the human personality traits neuroticism, conscientiousness, and openness significantly affected dog HCC. Hence, we suggest that dogs, to a great extent, mirror the stress level of their owners.

Tree phenology in montane forests of southern Ecuador can be explained by precipitation, radiation and photoperiodic control

We investigated the effect of seasonality on tree phenology in the tropical montane rain forest of southern Ecuador and analysed possible triggering factors. Two hypotheses were tested: (1) Interspecific synchronization of flowering and fruiting phenology is higher at study sites with pronounced rainfall seasonality compared with sites within perhumid forests. (2) Proximate causes for flowering in closely situated seasonal and perhumid sites are either photoperiodicity or climatic factors. Two nearby study sites with contrasting precipitation patterns were selected at the same altitude east and west of the western Cordillera. Eighty trees from 13 species were observed over a 2.5-y period. Three species were common to both study sites. Phenological and climate data were collected and cross-correlated by conducting a time-series analysis. At the perhumid site, very clear annual patterns of phenological behaviour could be observed for most of the selected rain-forest tree species, but with a poor interspecific synchronization. On the nearby seasonal site in contrast, most species showed high synchrony in their phenological behaviour coinciding with the dry season. There is strong evidence that flowering is induced not by one factor alone: we identified photoperiodic control, radiation and precipitation as possible proximate causes for both sites. Our results confirm studies which state that these factors are closely linked to each other in the tropics.

Resource allocation to reproductive organs during masting in the tropical emergent tree, Dipterocarpus tempehes

Some tree species exhibit large year-to-year variation in seed production, a phenomenon known as masting (Kelly 1994, Kelly & Sork 2002). Even in tropical rain forests, in which the climate is suitable for plant growth all year round with little seasonal variation (Whitmore 1998), there are many reports of masting (Appanah 1993, Hart 1995, Newbery et al. 1998, Newstrom et al. 1994, Wheelwright 1986). In particular, Dipterocarpaceae, the dominant family in lowland mixed dipterocarp forests in South-East Asia, undergo mast fruiting following mass-flowering with strong interspecific synchronization in aseasonal western Malesia (Appanah 1985, 1993; Ashton 1989, Ashton et al. 1988, Curran et al. 1999, Janzen 1974, Medway 1972, Sakai et al. 1999, Whitmore 1998, Wood 1956). In mixed-dipterocarp forests, dipterocarp species contribute more than 70% of the canopy biomass (Bruenig 1996, Curran & Leighton 2000). Masting of dipterocarp species is therefore likely to have a major impact on animal populations, and also on the nutrient cycle in such forest ecosystems by causing fluctuations in the availability of resources (Sakai 2002).