A Critical Review of the “Undoing Hypothesis”: Do Positive Emotions Undo the Effects of Stress?

Research in affective science has shown that trait positive affect reduces the risk of developing disease and is protective against the progression of certain diseases. Research also suggests that trait positive affect predisposes individuals to more frequent experiences of positive emotional states. The undoing effect has been proposed as a potential mechanism explaining how positive emotions influence health outcomes. According to this hypothesis, the experience of state positive emotions or positive affect contributes to faster recovery from the body’s physiological response to stress. This paper critically reviews literature concerning the undoing hypothesis. Several common methodological weaknesses were identified, including conceptual and design issues. Based on the reviewed studies two separate conclusions were drawn. First, there was insufficient evidence to conclude that the occurrence of positive emotional states speeds physiological recovery. Second, there was insufficient evidence to evaluate the undoing hypothesis as a potential mechanism through which state positive emotions affect health. Future research should focus on identifying the key parameters responsible for demonstrating the undoing effect when it is observed in order to understand how the experience of positive emotions may exert positive effects on health outcomes.     

Comparison of point counts and territory mapping for detecting effects of forest management on songbirds

Point counts are commonly used to assess changes in bird abundance, including analytical approaches such as distance sampling that estimate density. Point‐count methods have come under increasing scrutiny because effects of detection probability and field error are difficult to quantify. For seven forest songbirds, we compared fixed‐radii counts (50 m and 100 m) and density estimates obtained from distance sampling to known numbers of birds determined by territory mapping. We applied point‐count analytic approaches to a typical forest management question and compared results to those obtained by territory mapping. We used a before–after control impact (BACI) analysis with a data set collected across seven study areas in the central Appalachians from 2006 to 2010. Using a 50‐m fixed radius, variance in error was at least 1.5 times that of the other methods, whereas a 100‐m fixed radius underestimated actual density by >3 territories per 10 ha for the most abundant species. Distance sampling improved accuracy and precision compared to fixed‐radius counts, although estimates were affected by birds counted outside 10‐ha units. In the BACI analysis, territory mapping detected an overall treatment effect for five of the seven species, and effects were generally consistent each year. In contrast, all point‐count methods failed to detect two treatment effects due to variance and error in annual estimates. Overall, our results highlight the need for adequate sample sizes to reduce variance, and skilled observers to reduce the level of error in point‐count data. Ultimately, the advantages and disadvantages of different survey methods should be considered in the context of overall study design and objectives, allowing for trade‐offs among effort, accuracy, and power to detect treatment effects.     

Successful captive breeding of Mitchell's water monitor,Varanus mitchelli (Mertens 1958), at Perth Zoo

Mitchell's water monitors (Varanus mitchelli) have been maintained on display at Perth Zoo since 1997. They are generally a timid species but have been maintained and bred in a mixed species water feature exhibit. In this article we describe their captive management and behavior with an insight into their reproductive biology. Between 2002 and 2005, 11 clutches were laid ranging from 13 to 27 (X? = 20) eggs from one female. Egg size ranged between 3.00 and 6.08 g (X? = 4.77 g) in weight, 22.8 and 31.9 mm (X? = 28.3 mm) in length, and 11.1 and 19.3 mm (X? = 17.1 mm) in width. Oviposition included double and triple clutches ranging between 41 and 60 days apart (X? = 48 days), events n = 6. Four clutches were incubated at three different temperatures and hatchlings emerged after 157–289 days. The weight of the hatchlings ranged between 2.60 and 4.52 g (X? = 4.34 g). Total length ranged between 140.1 and 178.0 mm (X? = 165.9 mm) and snout–vent length ranged from 53.8 to 70.0 (X? = 64.4 mm). Juvenile growth and development information is presented from hatching through to approximately 3 years of age. Zoo Biol 29:615–625, 2010. © 2009 Wiley‐Liss, Inc.     

Geolocators reveal migratory connectivity between wintering and breeding areas of Golden‐winged Warblers

The conservation of migratory songbirds is often impeded by a lack of understanding of how populations in breeding and wintering areas are geographically linked (migratory connectivity). In recent years, light‐level geolocators have improved our understanding of migratory connectivity. Such information is valuable for evaluating how conservation efforts align between the breeding and non‐breeding areas of at‐risk species, and help to more effectively prioritize the allocation of conservation funding. Golden‐winged Warblers (Vermivora chrysoptera) are imperiled migratory songbirds, but the extent to which conservation efforts in their breeding and non‐breeding areas coincide with patterns of migratory connectivity are not well known. We used light‐level geolocators to evaluate the extent to which conservation actions targeting Golden‐winged Warblers in Nicaragua and in their breeding range in North America align with patterns of migratory connectivity. We recovered six of 22 geolocators that had been deployed on male Golden‐winged Warblers at the El Jaguar Reserve during the winter of 2015–2016. All six males migrated to breeding areas in the western Great Lakes region that includes eastern Minnesota, northern Wisconsin, southwestern Ontario, and Michigan's Upper Peninsula. All six males also had similar migration routes, with spring stopovers in southern Mexico, Guatemala, and Belize, a trans‐Gulf flight, and a stopover in the region of Louisiana, Arkansas, eastern Oklahoma, and Texas. Our results, in combination with those of previous studies, demonstrate strong migratory connectivity between portions of the breeding and winter distributions of Golden‐winged Warblers currently targeted for conservation. However, additional studies are needed to improve our understanding of the stopover ecology of Golden‐winged Warblers, especially in areas where they remain for extended periods of time. Finally, patterns of migratory connectivity revealed in our study should be used in combination with existing demographic parameters for Golden‐winged Warblers in the western Great Lakes and Nicaragua to help inform full life cycle population models for this imperiled songbird.     

Lengths and correlates of lag phases in upper-Midwest plant invasions

There are often lag phases in plant invasions, seemingly dormant periods between arrival in a new range and rapid population growth. Lags impede prioritization of invasive-species control efforts: when eradication is most feasible, it is often unclear whether a species is benign or a potentially harmful “sleeper weed.” I used herbarium records to estimate lag phases for invasive or potentially invasive plant species in three regions of the upper Midwest. I tested whether factors related to species’ invasion epidemiology, traits, or the habitats they invade were correlated with lag lengths. From an initial pool of 151 species, there were sufficient records to test for lags in 76 for northern Wisconsin, 90 for southern Wisconsin, and 91 for the southern Lake Michigan region. Lags were identified in 77% (197) of these 257 datasets and ranged from 3–140 years with a mean of 47.3 ± 34.6 (SD). Lags differed by native range, introduction pathway, growth form and habit, dispersal mode, flowering phenology, pollination mode for a subset of species, and breadth, light availability, and water availability of invaded habitats. However, estimated lags were highly variable and tested factors did not have strong explanatory power. Exotic species comprised an increasing proportion of total herbarium records. Of the species with known introduction pathways, 85% were intentionally introduced, mainly as ornamentals. The long durations, high variability, and low predictability of lags, along with human culpability for an increasingly non-native flora, support a cautious approach to species introductions.     

Chromosome Segregation Is Biased by Kinetochore Size

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Microsatellites and a single-nucleotide polymorphism differentiate apparentamylose classes in an extended pedigree of US rice germ plasm

 The Waxy gene (Wx) encodes the granule-bound starch synthase responsible for the synthesis of amylose in rice (Oryza sativa). Recently, a polymorphic microsatellite sequence closely linked to the Wx gene was reported. To determine whether polymorphism in this sequence correlates with variation in apparent amylose content, we tested an extended pedigree of 92 current and historically important long-, medium- and short-grain US rice cultivars representing the efforts of many breeders over more than 80 years. Seven Wx microsatellite alleles were identified which together explained 82.9% of the variation in apparent amylose content of the 89 non-glutinous rice cultivars tested. Similar results were also obtained with 101 progenyof a cross between low- and intermediate-amylose breeding lines. An additional, unique microsatelliteallele, (CT)₁₆, was detected in one glutinous cultivar,CI 5309. However, the other glutinous cultivars,Calmochi 101 and Tatsumi mochi, were in the (CT)₁₇ class along with three other cultivars that contained15–16.5% amylose. We sequenced a 200-bp PCR-amplified fragment containing the CT microsatellite and the putative 5′ splice site of the Wx leader intron from a subset of 42 cultivars representing all eight microsatellite alleles. All of the cultivars with 18% or less amylose had the sequence AGTTATA at the putative leader intron 5′ splice site, while all cultivars with a higher proportionof amylose had AGTTATA. This single nucleotidesubstitution could also be assayed by AccI digestion of the amplified fragment. Overall, this single nucleotide polymorphism could explain 79.7% of the variation in the apparent amylose content of the 89 non-glutinous cultivars tested. Interestingly, cultivars in the (CT)₁₉ microsatellite classes that differed substantially in amylose content still showed the correlation between this G-T polymorphism and apparent amylose content. The G-T polymorphism at this site was not, however, able to explain the very low amylose contents of the three glutinous cultivars tested, all of which had the sequence AGTTATA. Received: 31 July 1996 / Accepted: 22 November 1996