• Aggression and hormones are associated with heterogeneity in parasitism and parasite dynamics in the brown mouse lemur

      Zohdy, Sarah; Bisanzio, Donal; Tecot, Stacey; Wright, Patricia C.; Jernvall, Jukka; Univ Arizona, Sch Anthropol (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2017-10)
      Animal behaviours, like aggression, can directly affect host health by influencing exposure to parasites. Aggressive individuals may experience an increase in agonistic interactions and contact rates with conspecifics, which might increase their probability of acquiring parasites. However, aggression is not the only factor that shapes parasitism; proximate mechanisms like hormone-modulated immunosuppression can also have broad impacts. Here, we hypothesized that high levels of aggression, cortisol and testosterone would be positively associated with parasitism and that aggressive individuals would play a larger role spreading parasites to conspecifics than would docile individuals. We measured aggression using the level of aggressive response to human handling during capture. Our aim was to examine associations between aggression and hormones (cortisol and testosterone) on variation in endo-and ectoparasitism in a population of wild mouse lemurs (Microcebus rufus) over a 3-year period. By tracking the movement of lice (directly transmitted parasites) in the population, we also examined the effect of host aggression on population-wide parasite dynamics. We show that animals with high testosterone and cortisol were more likely to exhibit aggressive behaviours, and cortisol was associated with significantly higher ectoparasite infestations. Aggressive individuals were significantly more infested by lice, and also donated significantly more lice to conspecifics in the population. Taken together, our results offer insight into the individual and population health costs of aggression, and empirical support of a trade-off between aggression and ectoparasitism, which may have driven the evolution of aggression and interactions with conspecifics. (C) 2017 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
    • Beyond bioproductivity: Engaging local perspectives in land degradation monitoring and assessment

      Herrmann, Stefanie; Diouf, Abdoul Aziz; Sall, Ibrahima; Univ Arizona (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2020-02)
      Land degradation monitoring and assessment in the Sahel zone has relied substantially on temporal trends of remote sensing-based vegetation indices, which are proxies for the bioproductivity of the land. However, prior studies have shown that negative or positive trends in bioproductivity are not necessarily associated with degradation or improvement of land condition. In this short communication, while acknowledging the contributions of remote sensing-based indices and global-scale datasets to dismantling an outdated desertification narrative, we argue that local land users have much to contribute to our understanding of land degradation, and particularly to ensuring that scientific assessments of degradation capture variables relevant to them. We used the participatory photo elicitation method in three sites in the Senegalese Ferlo in order to elicit local pastoralists' perspectives on land degradation and identify the indicators that they use to characterize pasture quality, while empowering them to lead the discussion. The discussion revealed indicators far beyond bioproductivity, including livestock performance as well as composition and quality of the herbaceous and woody vegetative cover, invasive species, soil quality and water availability. We found that the pastoralists' knowledge and interest in the issue could potentially be harnessed more systematically, and at larger scales, in order to build a spatially explicit field-based knowledge base of land degradation complementary to remote sensing-based maps of trends in bioproductivity. Such a dataset could serve as a standalone product or as a reference dataset for development and validation of remote sensing-based indicators.
    • Canyon Creek revisited: New investigations of a late prehispanic turquoise mine, Arizona, USA

      Hedquist, Saul L.; Thibodeau, Alyson M.; Welch, John R.; Killick, David J.; Univ Arizona, Sch Anthropol (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2017-11)
      Turquoise has been used in the American Southwest since "time immemorial," and remains an important material for contemporary indigenous groups of the region. Detailed studies of ancient turquoise mines are few, however, and inferences of turquoise procurement and provenance have been limited. Our intensive investigation of one mine, the Canyon Creek locale in Arizona, integrates archaeology and geochemistry to enhance understanding of the mine and its output. A detailed description of the mine's morphology and geologic setting lays foundations for interpreting an isotopic analysis of specimens from the mine's four localities. The analysis reveals extremely radiogenic Pb isotope ratios, which distinguish Canyon Creek turquoise from that of other known sources in the American Southwest. Its distinctive isotopic signature makes Canyon Creek turquoise readily identifiable in archaeological assemblages. The presence of turquoise from Canyon Creek at late prehispanic settlements in east-central Arizona helps clarify the mine's chronology of use and regional distribution. Our observations suggest the mine was larger than previously supposed, and that it provided an important source of turquoise for inhabitants of the region during the thirteenth and fourteenth centuries AD. (C) 2017 Elsevier Ltd. All rights reserved.
    • Differential resistance and resilience of functional groups to livestock grazing maintain ecosystem stability in an alpine steppe on the Qinghai-Tibetan Plateau

      Ganjurjav, Hasbagan; Zhang, Yong; Gornish, Elise S; Hu, Guozheng; Li, Yue; Wan, Yunfan; Gao, Qingzhu; Univ Arizona, Sch Nat Resources & Environm (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2019-12-01)
      Ecosystem stability is one of the main factors maintaining ecosystem functioning and is closely related to temporal variability in productivity. Resistance and resilience reflect tolerance and recovering ability, respectively, of a plant community under perturbation, which are important for maintaining the stability of ecosystems. Generally, heavy grazing reduces the stability of grassland ecosystems, causing grassland degradation. However, how livestock grazing affects ecosystem stability is unclear in alpine steppe ecosystems. We conducted a five-year grazing experiment with Tibetan sheep in a semi-arid alpine steppe on the Qinghai-Tibetan Plateau, China. The experimental treatments included no grazing (NG), light grazing (LG, 2.4 sheep per ha), moderate grazing (MG, 3.6 sheep per ha) and heavy grazing (HG, 6.0 sheep ha). We calculated resistance and resilience of three plant functional groups and ecosystem stability under the three grazing intensities using aboveground primary productivity. The results showed that with increasing grazing intensity, aboveground biomass of each functional group significantly decreased. As grazing intensity increased, the resistance of forbs first increased then decreased. The resilience of graminoids in HG was significantly lower than in LG plots, but the resilience of legumes in HG was higher than in LG and MG plots. The resilience of graminoids was significantly higher than legume and forbs under LG and MG treatments. In HG treatments, resilience of legumes was higher than graminoids and forbs. Ecosystem stability did not change under different grazing intensities, because of dissimilar performance of the resilience and resistance of functional groups. Our results highlight how the differential resistance and resilience of different function groups facilitate the tolerance of alpine steppe to grazing under even a heavy intensity. However, the degradation risk of alpine steppe under heavy grazing still needs to be considered in grassland management due to sharp decreases of productivity.
    • An ecohydrological stream type classification of intermittent and ephemeral streams in the southwestern United States

      Levick, Lainie; Hammer, Samantha; Lyon, Russell; Murray, Joel; Birtwistle, Amy; Guertin, Phillip; Goodrich, David; Bledsoe, Brian; Laituri, Melinda; Univ Arizona (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2018-08)
      An ecohydrological stream type classification was developed to improve decision making for ephemeral and intermittent streams at four military reservations in the southwestern U.S.: Fort Irwin, Yuma Proving Ground (YPG), Fort Huachuca, and Fort Bliss. Agglomerative hierarchical cluster analysis was used to classify stream reaches by ecohydrologic properties (vegetation, hydrologic, and geomorphic attributes derived using geographic information system analyses), and Classification and Regression Trees (CART) were used to determine thresholds for each variable for a predictive model. Final stream types were determined from statistical analyses, cluster validity tests, examination of mapped clusters, and site knowledge. Climate regime and geomorphology were most important for YPG and Fort Irwin where annual precipitation is low. Vegetation variables were important at Fort Bliss and hydrologic variables were important at Fort Huachuca where higher annual precipitation and a bimodal rainfall pattern occur. The classification results and input variables are spatially linked to specific stream reaches, allowing managers to identify locations with similar attributes to support management actions. These methods enable the development of a stream type classification in gauged or ungauged watersheds and for areas where intensive field data collection is not feasible.
    • Interactions among interactions: The dynamical consequences of antagonism between mutualists

      Yule, Kelsey M; Johnson, Christopher A; Bronstein, Judith L; Ferrière, Régis; Univ Arizona, Dept Ecol & Evolutionary Biol; Univ Arizona, Paris Sci & Lettres Univ, Int Res Lab Interdisciplinary Global Environm Stu (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2020-05-31)
      Species often interact with multiple mutualistic partners that provide functionally different benefits and/or that interact with different life-history stages. These functionally different partners, however, may also interact directly with one another in other ways, indirectly altering net outcomes and persistence of the mutualistic system as a whole. We present a population dynamical model of a three-species system involving antagonism between species sharing a mutualist partner species with two explicit life stages. We find that, regardless of whether the antagonism is predatory or non-consumptive, persistence of the shared mutualist is possible only under a restrictive set of conditions. As the rate of antagonism between the species sharing the mutualist increases, indirect rather than direct interactions increasingly determine species' densities and sometimes result in complex, oscillatory dynamics for all species. Surprisingly, persistence of the mutualistic system is particularly dependent upon the degree to which each of the two mutualistic interactions is specialized. Our work investigates a novel mechanism by which changing ecological conditions can lead to extinction of mutualist partners and provides testable predictions regarding the interactive roles of mutualism and antagonism in net outcomes for species' densities. (C) 2020 Elsevier Ltd. All rights reserved.
    • Perceptual categorization and bilingual language modes: Assessing the double phonemic boundary in early and late bilinguals

      Casillas, Joseph V.; Simonet, Miquel; Univ Arizona (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2018-08-10)
      In the present study, Spanish-English bilinguals' perceptual boundaries between voiced and voiceless stops (a/b/-/p/ continuum including pre-voiced, voiceless unaspirated, and voiceless aspirated tokens) are shown to be modulated by whether participants are "led to believe" they are classifying Spanish or English sounds. In Experiment 1, simultaneous Spanish-English bilinguals and beginner second-language learners of Spanish labeled the same acoustic continuum in two experimental sessions (Spanish mode, English mode), and both groups were found to display language-specific perceptual boundaries (or session effects). In Experiment 2, early bilinguals and late second-language learners of various levels of proficiency participated in a single session in which, in random order, they labeled nonwords that were designed to prime either Spanish or English language modes. Early bilinguals and relatively proficient second-language learners, but not less proficient learners, displayed mode-specific perceptual normalization criteria even in conditions of rapid, random mode switching. Along with similar ones, the experiments reported here demonstrate that bilinguals are able to exploit language-specific perceptual processes (or norms) when processing speech sounds, which entails some degree of separation between their sound systems.
    • The phonetic specificity of competition: Contrastive hyperarticulation of voice onset time in conversational English

      Nelson, Noah; Wedel, Andrew; Univ Arizona, Dept Linguist (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2017-09)
      Competition between words in the lexicon is associated with hyperarticulation of phonetic properties in production. This correlation has been reported for metrics of competition varying in the phonetic specificity of the relationship between target and competitor (e.g., neighborhood density, onset competition, cue-specific minimal pairs). Sampling a systematic array of competition metrics, we tested their ability to predict voice onset times in both voiced and voiceless word-initial stops of conversational English. Linear mixed effects models were compared according to their corrected Akaike’s Information Criterion (AICc) values. High-performing models were evaluated using evidence ratios, with the competition metrics of top-performing models tested for significance using nested model comparisons. Words with a minimal pair defined for initial stop voicing were contrastively hyperarticulated, with shorter voice onset times for voiced stops and longer voice onset times for voiceless stops. No other competition metric reliably predicted hyperarticulation for both stop types. These results suggest that contrastive hyperarticulation is phonetically specific, increasing the perceptual distance between target and competitor.
    • Understanding the perception of stakeholders in reducing adolescent-to-parent violence/aggression

      Shanholtz, Caroline E; O'Hara, Karey L; Duchschere, Jennifer E; Beck, Connie J; Lawrence, Erika; Univ Arizona, Dept Psychol (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2020-04)
      Introduction: Adolescent-to-parent violence/aggression (APV/A) is an understudied yet increasingly common social problem for adolescents and families, particularly those involved in the juvenile justice system. The current study focused on improving interventions for this population by gathering qualitative data from stakeholders to inform treatment targets. Methods: Participants (N = 23) comprised of court professionals (n = 7), parents/guardians (n = 9), and their male adolescent children (n = 7) in the United States. Parent and adolescent participants were recruited through monthly court-mandated domestic violence education classes offered by the juvenile court. Parent/guardian participants were between the ages of 38 and 77 and consisted of four males and five females. Adolescents were between the ages of 14 and 17. Court professional participants consisted of judges, probation officers, and court psychologists. Semi-structured interviews were analyzed qualitatively using grounded theory. Results: Results indicated that, from the perspective of key stakeholders, an effective intervention to reduce APV/A likely involves a two-pronged approach: (1) address specific and theoretically modifiable emotional, behavioral, and psychological factors at the adolescent-level; and (2) induce change in the family system by addressing environmental barriers to seeking treatment and by creating positive family relationships. Conclusions: The present study aimed to gather the perspectives of court professionals, adolescents, and parents/guardians regarding the development of an effective intervention for APV/A-involved families. This study represents the first step toward the development of a feasible, acceptable, sustainable, and effective intervention for adolescents and their families who are involved in the juvenile justice system due to APV/A.