Genetic evidence for multiple parentage in eastern kingbirds (Tyrannus tyrannus)

Summary Electrophoretic analysis was performed on 28 families of eastern kingbirds (Tyrannus tyrannus) from northern Michigan to estimate the occurrence of multiple parentage. Out of 19 families used in the final analysis, at least one putative parent was excluded in 9 families, or 18 out of 60 offspring (30% of offspring). Distribution of exclusion types conforms most closely to a model of quasi-parasitism, rather than extra-pair fertilizations, with secondary females laying their eggs in the primary female's nest, but random brood parasitism cannot be ruled out as an additional or alternative source of stray genes. Based on the model of random parasitism, an estimated 39% of all offspring in this population may be unrelated to one or both of the putative parents, or 53% based on a model of quasi-parasitism. Heretofore, eastern kingbirds have been considered to be exclusively monogamous; no behavioral evidence for alternative reproductive strategies has ever been reported for this species.     

Genetic Diversity in a Threatened Wetland Species, Helonias bullata (Liliaceae)

Genetic variation was examined in Helonias bullata , a threatened perennial plant species that occurs in isolated wetland habitats. Fifteen populations representing the species' geographic range were sampled. Genetic diversity was low for the species ( H _es = 0.053) as well as within populations ( H _ep = 0.029). Of the 33 allozyme loci examined, 11 (33%) were polymorphic, while on average only 12.8% (4) of the loci were polymorphic within populations. The number of alleles per polymorphic locus was 2.36 for the species and averaged 2.09 across populations. For every genetic parameter calculated, variation in H. bullata was lower than that typically found for narrowly distributed plant species. The lowest levels of genetic diversity were found in northern areas that were colonized following the last glacial epoch. The number of genotypes detected per population ranged from three to 21, with a mean of 13 for this clonally reproducing species. We found a relatively high proportion of total genetic diversity (30.6%) among populations and a significant correlation (p < 0.002) between genetic distance and geographic distance. Genetic drift phenomena appear to play a major role in the population genetics of this species. Anomalously, several populations that appeared most limited in size and vigor were genetically most variable, perhaps because they represent older, relictual populations. Life-history characteristics of H. bullata coupled with low levels of genetic diversity and the degradation and disappearance of wetlands threaten the existence of this species.     

Enhancing older driver safety: A driving survey and evaluation of the CarFit program

Objective

To evaluate CarFit, an educational program designed to promote optimal alignment of driver with vehicle.

Methods

A driving activity survey was sent to 727 randomly selected participants living in retirement communities. Drivers (n = 195) were assigned randomly to CarFit intervention (n = 83, M age = 78.1) or Comparison (n = 112, M age = 79.6) groups. After 6 months, participants completed a post-test of driving activity and CarFit recommendations.

Results

Nonconsenting drivers were older and participated in fewer driving activities. CarFit participation was moderate (71%) with 86% of the participants receiving recommendations. 60% followed the recommendations at the 6-month re-evaluation). The CarFit (67.6%) and Comparison (59.3%) groups reported at least one type of self-regulation of driving activity at baseline. There was no significant change in the driving behaviors at the six-month follow-up.

Conclusion

CarFit was able to detect addressable opportunities that may contribute to the safety of older drivers.

Impact on industry

CarFit recommendations may need stronger reinforcement in order to be enacted by a participant.     

Detrimental effects of carotenoid pigments: the dark side of bright coloration

Carotenoid pigments produce yellow, orange, and red integumentary color displays that can serve as reliable signals of health and condition. In many birds and fish, individuals gain competitive or mating advantages by ingesting and utilizing large quantities of carotenoid pigments. Carotenoid pigments serve as antioxidants, performing important functions as free-radical scavengers. The beneficial effects of carotenoid pigments are well documented, but rarely have researchers considered potential detrimental effects of high-level accumulation of carotenoids. We maintained American goldfinches (Carduelis tristis) on high- or low-carotenoid diets through molt and tested for damage to the liver and skeletal muscle. High intake of carotenoids had no measurable effect on liver enzymes but caused an increase in creatine kinase, an indicator of skeletal muscle breakdown, and a reduction in vertical flight performance, a measure of skeletal muscle integrity. The detrimental effects of high-level carotenoid accumulation were approximately equivalent to the negative effects of removing carotenoids from the diet. The adverse effects observed in this study have important implications for theories of the function and evolution of colorful plumage.     

Understanding stewardship behaviour: factors facilitating and constraining private water well stewardship

Regulatory frameworks to ensure municipal drinking water safety exist in most North American jurisdictions. However, similar protection is rarely provided to people reliant on water provided from private wells. In Canada, approximately 4 million people depend on privately owned, domestic wells for their drinking water. Numerous studies have shown that people who rely on private wells for their water supplies are at risk from nitrate and bacterial contamination. Given the fact that regulations relating to private wells tend to be weak or poorly enforced, actions taken by well owners to protect their own drinking water safety are extremely important. Drawing on one of the largest and most comprehensive surveys of private well owners ever conducted in Canada or elsewhere, this paper explores factors that influence well owner stewardship behaviour. Key behaviours examined included annual testing of well water and inspection of wells, measures to protect water quality, and proper decommissioning of unused wells. A geographically-stratified survey, sent to 4950 well owners in Ontario, Canada, resulted in an effective response rate of 34% (n = 1567). Logistic regression analyses revealed that motivations for well stewardship behaviours included reassurance, the perception of problems, and knowledge of the environment. Knowing how to perform stewardship behaviours was an important antecedent to action. Barriers to stewardship included complacency, inconvenience, ignorance, cost, and privacy concerns. To promote stewardship, local initiatives, better educational materials, and enforcement through real estate laws are all required. Ultimately, drinking water safety for people reliant on private wells is shown to be a responsibility shared by governments and private well owners.     

Comparing Hydrogeomorphic Approaches to Lake Classification

A classification system is often used to reduce the number of different ecosystem types that governmental agencies are charged with monitoring and managing. We compare the ability of several different hydrogeomorphic (HGM)—based classifications to group lakes for water chemistry/clarity. We ask: (1) Which approach to lake classification is most successful at classifying lakes for similar water chemistry/clarity? (2) Which HGM features are most strongly related to the lake classes? and, (3) Can a single classification successfully classify lakes for all of the water chemistry/clarity variables examined? We use univariate and multivariate classification and regression tree (CART and MvCART) analysis of HGM features to classify alkalinity, water color, Secchi, total nitrogen, total phosphorus, and chlorophyll a from 151 minimally disturbed lakes in Michigan USA. We developed two MvCART models overall and two CART models for each water chemistry/clarity variable, in each case comparing: local HGM characteristics alone and local HGM characteristics combined with regionalizations and landscape position. The combined CART models had the highest strength of evidence (ω_i range 0.92–1.00) and maximized within class homogeneity (ICC range 36–66%) for all water chemistry/clarity variables except water color and chlorophyll a. Because the most successful single classification was on average 20% less successful in classifying other water chemistry/clarity variables, we found that no single classification captures variability for all lake responses tested. Therefore, we suggest that the most successful classification (1) is specific to individual response variables, and (2) incorporates information from multiple spatial scales (regionalization and local HGM variables).     

Nitrate production and availability in residential soils

The rapid increase in residential land area in the United States has raised concern about water pollution associated with nitrogen fertilizers. Nitrate (NO3-) is the form of reactive N that is most susceptible to leaching and runoff; thus, a more thorough understanding of nitrification and NO3(-) availability is needed if we are to accurately predict the consequences of residential expansion for water quality. In particular, there have been few assessments of how the land use history, housing density, and age of residential soils influence NO3(-) pools and fluxes, especially at depth. In this study, we used 1 m deep soil cores to evaluate potential net nitrification and mineralization, microbial respiration and biomass, and soil NO3(-) and NH4+ pools in 32 residential home lawns that differed by previous land use and age, but had similar soil types. These were compared to eight forested reference sites with similar soils. Our results suggest that a change to residential land use has increased pools and production of reactive N, which has clear implications for water quality in the region. However, the results contradict the common assumption that NO3(-) production and availability is dramatically higher in residential soils than in forests in general. While net nitrification (128.6 +/- 15.5 mg m(-2) d(-1) vs. 4.7 +/- 2.3 mg m(-2) d(-1); mean +/- SE) and exchangeable NO3(-) (3.8 +/- 0.5 g/m2 vs. 0.7 +/- 0.3 g/m2) were significantly higher in residential soils than in forest soils in this study, these measures of NO3(-) production and availability were still notably low, comparable to deciduous forest stands in other studies. A second unexpected result was that current homeowner management practices were not predictive of NO3(-) availability or production. This may reflect the transient availability of inorganic N after fertilizer application. Higher housing density and a history of agricultural land use were predictors of greater NO3(-) availability in residential soils. If these factors are good predictors across a wider range of sites, they may be useful indicators of NO3(-) availability and leaching and runoff potential at the landscape scale.