Of Population and False Hopes: Malthus and His Legacy

Population and Environment -     

Carrying Capacity Reconsidered

The concept of carrying capacity has gained broad currency, although some population ecologists are dubious about its value. This paper assesses the utility of the concept and develops an alternative understanding of population growth. First, carrying capacity is viewed in historical perspective and evidence that is supposed to support it is criticized. Then the underlying assumptions upon which it rests are reexamined. Limits to growth are seen to be both multiple and variable. The mechanism that is supposed to regulate population is critically reviewed. And the assumptions of balance in nature and equilibrium in biotic communities are reevaluated. These assumptions having been found wanting, population growth is reassessed in relation to environmental variability. The strategies by which different species cope with variability are described, and the windfall effect, which causes some populations to grow rapidly and then collapse, is identified. Finally, it is suggested that carrying capacity may be a self-validating belief and that is has limited relevance to human population growth, which is better understood in other ways.     

The effects of urbanization on body size of larval stream salamanders

Animal body sizes in urban areas often differ from nearby rural areas, which may impact population fitness and dynamics. We examined the effects of urbanization on larval body sizes of two species of salamanders, the two-lined salamander (Eurycea cirrigera) and the northern dusky salamander (Desmognathus fuscus). Specifically, we utilized a before-after control-impact (BACI) study design which allowed for the assessment of differences in larval body size between multiple control and impacted sites over a 5 year period. We found a decrease in larval body size in both species at the impacted sites compared to control sites in the first year after urbanization, followed by generally larger body sizes in urban sites compared to control sites in years 3–5, and significantly so in year 4. Using generalized linear models, we found support that larger body sizes post impact in urbanized streams may be due to warmer stream water temperature and decreased abundance of larvae. Both E. cirrigera and D. fuscus are well known for their ability to persist in urbanized streams; our data suggest that despite overall lower abundances in urban streams, persistence may be due to increases in larval body size and, potentially, post-metamorphic benefits.     

Models, assumptions and model checking in ecological regressions

Ecological regression is based on assumptions that are untestable from aggregate data. However, these assumptions seem more questionable in some applications than in others. There has been some research on implicit models of individual data underlying aggregate ecological regression modelling. We discuss ways in which these implicit models can be checked from aggregate data. We also explore the differences in applications of ecological regressions in two examples: estimating the effect of radon on lung cancer in the United States and estimating voting patterns for different ethnic groups in New York City.     

Retired women and volunteering: the good, the bad, and the unrecognized

In this article, we examine varied attitudes and practices toward volunteering in later life, as shared by a group of 40 retired women. We categorize women based on their engagement in retirement and label the categories according to societal expectations as follows: traditional volunteers as "good," nonvolunteers as "bad," and caregiving volunteers as "unrecognized." Using critical gerontology and a feminist framework, we juxtapose the lived experiences of retired women with a prevailing discourse on successful aging and civic engagement. We advocate for societal recognition of caregiving as a valuable form of volunteering, as well as the need to respect multiple ways in which older women experience and find meaning in later life.     

Maternal anxiety and toddler inhibited temperament predict maternal socialization of worry

Parent emotion socialization refers to the process by which parents impart their values and beliefs about emotional expressivity to their children. Parent emotion socialization requires attention as a construct that develops in its own right. The socialization of child worry, in particular, has implications for children’s typical socioemotional development, as well as their maladaptive development toward anxiety outcomes. Existing theories on emotion socialization, anxiety, and parent–child relationships guided our investigation of both maternal anxiety and toddler inhibited temperament as predictors of change in mothers’ unsupportive (i.e., distress, punitive, and minimizing) responses to toddler worry across 1 year of toddlerhood. Participants included 139 mother–toddler dyads. Mothers reported on their own anxiety and their emotion socialization responses to toddler worry. We assessed toddler inhibited temperament through a mother‐report survey of shyness and observational coding of dysregulated fear. Maternal anxiety but not child inhibited temperament predicted distress reactions and punitive responses, whereas maternal anxiety and toddler dysregulated fear both uniquely predicted minimizing responses. These results support the continued investigation of worry socialization as a developmental outcome of both parent and child characteristics.     

Aspects of the ecology and behaviour of a potential urban exploiter,the southern tree agama,Acanthocercus atricollis

Urbanisation has caused significant alterations to ecosystems, generally resulting in decreased biodiversity. However, certain animal species persist and thrive in urban environments by making use of available opportunities, anthropogenic resources, infrastructure and increased ambient and surface temperatures. These species are known as urban exploiters. We investigated the southern tree agama, Acanthocercus atricollis population trends, habitat use and basking and shading behaviour in a high-density urban human-populated housing metropolitan area in Pietermaritzburg, KwaZulu-Natal, South Africa. We marked individual southern tree agamas to determine habitat use and territories (n?=?37). The southern tree agama population density was high, and they had established set territories here. We conducted monthly observations (February 2017–July 2017 and March 2018–February 2019) to determine the degree of basking and shading behaviour with season and time of day and location. Southern tree agamas invested more than half of their time (57%) in basking behaviour during the overall observational study period. Basking and shading patterns changed with season and time of day. The number of basking southern tree agamas decreased during winter and basking commenced later. We found that increased anthropogenic infrastructure and supplementary food availability, decreased predators, and basking opportunities could have had an influence on their population increase and that the southern tree agama is a potential urban exploiter.

     

ARE GOALS AND TOPICS INFLUENCED BY GENDER AND MODALITY IN THE INITIAL MARRIAGE AND FAMILY THERAPY SESSION?

Establishment of a goal is crucial to therapy, but identification of therapeutic goals may be difficult in conjoint therapy because each participant may identify a different problem. We examined the influence of gender on ability to successfully introduce therapeutic topics in marital and family therapy by conducting two studies. The first study evaluates the ability of therapists to identify therapeutic goals that matched goals prioritized by both women and men clients on pretherapy questionnaires. The second study examines the process of initial therapy sessions to see whether gender influences a client's ability to introduce a therapeutic topic. Results suggest that therapeutic topic is influenced by the interaction of gender and treatment modality. Specifically, therapists were better able to match women's pretherapy stated goals in marital therapy than family therapy, men were more successful at introducing topics in family therapy, and women were more successful at introducing topics in marital therapy.