Twinning and the r/K Reproductive Strategy: A Critique of Rushton's Theory

1992 ◽  
Vol 41 (1) ◽  
pp. 73-83 ◽  
Author(s):  
G. Allen ◽  
A.W. Eriksson ◽  
J. Fellman ◽  
P. Parisi ◽  
S.G. Vandenberg
Keyword(s):  
Environmental Factors ◽  
Population Growth ◽  
Parental Care ◽  
Ethnic Groups ◽  
Ethnic Differences ◽  
Reproductive Strategy ◽  
Reproductive Strategies ◽  
Human Populations ◽  
Efficient Utilization ◽  
Mode Of Reproduction

AbstractThe theory of r selection, favoring population growth, as opposed to K selection, favoring more efficient utilization of resources, has in recent years been applied by Rushton to contrast human ethnic groups in terms of their r/K reproductive strategies, suggesting the existence of a continuum from r groups, producing many offspring but providing little parental care, to K groups, producing few offspring but providing much parental care. Rushton's theory, which is largely based on ethnic differences in twinning rates, is here critically examined. It is pointed out that twinning rate differences are not necessarily genetic in origin since various environmental factors clearly play a role, and also that twinning, as a mode of reproduction, is not necessarily an r strategy, considering the high prenatal and perinatal selection to which it has been, and still is, associated. Moreover, Rushton misinterprets a number of relevant aspects related to the biology of twinning. The claim that ethnic differences in twinning rates provide evidence for an r/K typology in human populations with respect to reproductive strategies does not appear to be warranted.

Atypical reproduction in a syllid worm: the stolon of Syllis rosea (Annelida, Syllidae) takes care of its offspring

2020 ◽  
Vol 100 (2) ◽  
pp. 221-227
Author(s):  
Joachim Langeneck ◽  
Michela Del Pasqua ◽  
Margherita Licciano ◽  
Adriana Giangrande ◽  
Luigi Musco
Keyword(s):  
Parental Care ◽  
Sexual Reproduction ◽  
Reproductive Strategy ◽  
Reproductive Strategies ◽  
Congeneric Species ◽  
Reproduction Mode ◽  
Laboratory Rearing ◽  
Larval Stages ◽  
The Family ◽  
Reproductive Cycles

AbstractThe family Syllidae, aside from representing the most species-rich family in Annelida, is characterized by a number of sexual and asexual reproductive strategies. With the exception of a few viviparous species, the subfamily Syllinae is characterized by schizogamous reproduction with pelagic larval stages and without parental care. Laboratory rearing of ripe specimens of Syllis rosea showed a different reproductive strategy, hitherto unknown in this subfamily. While male stolons rapidly degenerated after fertilization, female ones released large eggs in a gelatinous cluster attached to the middle-posterior chaetigers. The gel mass progressively compacted as a cocoon wrapped by the stolon body; 7 days after the deposition the larvae hatched out from the cocoon at the metatrochophore stage and the female stolon died after a few days. After hatching the larvae remained associated to the stolon, and young specimens of S. rosea survived up to the 3-chaetiger stage. Until now cocoon brooding by the stolon has only been reported for some Autolytinae. The production of gelatinous egg masses and parental care are known in basally branching clades within Syllidae, suggesting that this reproduction mode might retain some ancestral features. The scarce knowledge about reproductive cycles in Syllinae does not allow clarification whether this strategy is unique for S. rosea, or it occurs in other congeneric species. Further research is needed to understand possible relationships between sexual reproduction and phylogeny, stolon morphology and its adaptation to parental care, and ultimately between reproductive strategies and ecology.

scholarly journals Decreased heritability and emergence of novel genetic effects on pulse wave velocity from youth to young adulthood

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yisong Huang ◽  
Shaoyong Su ◽  
Harold Snieder ◽  
Frank Treiber ◽  
Gaston Kapuku ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Pulse Wave Velocity ◽  
Wave Velocity ◽  
Young Adulthood ◽  
Ethnic Differences ◽  
Genetic Factors ◽  
Pulse Wave ◽  
Environmental Influences ◽  
Genetic Effects ◽  
Over Time

AbstractIncreased arterial stiffness measured by pulse wave velocity (PWV) is an important parameter in the assessment of cardiovascular risk. Our previous longitudinal study has demonstrated that carotid-distal PWV showed reasonable stability throughout youth and young adulthood. This stability might be driven by genetic factors that are expressed consistently over time. We aimed to illustrate the relative contributions of genetic and environmental factors to the stability of carotid-distal PWV from youth to young adulthood. We also examined potential ethnic differences. For this purpose, carotid-distal PWV was measured twice in 497 European American (EA) and African American (AA) twins, with an average interval time of 3 years. Twin modelling on PWV showed that heritability decreased over time (62–35%), with the nonshared environmental influences becoming larger. There was no correlation between the nonshared environmental factors on PWV measured at visit 1 and visit 2, with the phenotypic tracking correlation (r = 0.32) completely explained by shared genetic factors over time. Novel genetic influences were identified accounting for a significant part of the variance (19%) at the second measurement occasion. There was no evidence for ethnic differences. In summary, novel genetic effects appear during development into young adulthood and account for a considerable part of the variation in PWV. Environmental influences become larger with age for PWV.

scholarly journals Ethnic Disparities in the Development of Sight-Threatening Diabetic Retinopathy in a UK Multi-Ethnic Population with Diabetes: An Observational Cohort Study

2021 ◽  
Vol 11 (8) ◽  
pp. 740
Author(s):  
Manjula D. Nugawela ◽  
Sarega Gurudas ◽  
Andrew Toby Prevost ◽  
Rohini Mathur ◽  
John Robson ◽  
...  
Keyword(s):  
Ethnic Groups ◽  
Ethnic Differences ◽  
Minority Groups ◽  
Treatment Options ◽  
Ethnic Disparities ◽  
Ethnic Minority Groups ◽  
The United Kingdom ◽  
Increased Risk ◽  
Observational Cohort ◽  
General Practices

There is little data on ethnic differences in incidence of DR and sight threatening DR (STDR) in the United Kingdom. We aimed to determine ethnic differences in the development of DR and STDR and to identify risk factors of DR and STDR in people with incident or prevalent type II diabetes (T2DM). We used electronic primary care medical records of people registered with 134 general practices in East London during the period from January 2007–January 2017. There were 58,216 people with T2DM eligible to be included in the study. Among people with newly diagnosed T2DM, Indian, Pakistani and African ethnic groups showed an increased risk of DR with Africans having highest risk of STDR compared to White ethnic groups (HR: 1.36 95% CI 1.02–1.83). Among those with prevalent T2DM, Indian, Pakistani, Bangladeshi and Caribbean ethnic groups showed increased risk of DR and STDR with Indian having the highest risk of any DR (HR: 1.24 95% CI 1.16–1.32) and STDR (HR: 1.38 95% CI 1.17–1.63) compared with Whites after adjusting for all covariates considered. It is important to optimise prevention, screening and treatment options in these ethnic minority groups to avoid health inequalities in diabetes eye care.

Individual, household and environmental factors associated with arboviruses in rural human populations, Brazil

2021 ◽  
Author(s):  
Lilian S. Catenacci ◽  
Milene S. Ferreira ◽  
Debora Fernandes ◽  
Hannah Padda ◽  
Elizabeth S. Travassos‐da‐Rosa ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Human Populations ◽  
Factors Associated ◽  
Individual Household

Applying the Health Belief Model to Characterize Racial/Ethnic Differences in Digital Conversations Related to Depression Pre– and Mid–COVID-19 (Preprint)

2021 ◽  
Author(s):  
Ruby Castilla-Puentes ◽  
Jacqueline Pesa ◽  
Caroline Brethenoux ◽  
Patrick Furey ◽  
Liliana Gil Valletta ◽  
...  
Keyword(s):  
Health Belief Model ◽  
Ethnic Groups ◽  
Ethnic Differences ◽  
Health Belief ◽  
Depression Symptoms ◽  
Seeking Help ◽  
Key Drivers ◽  
Race Ethnicity ◽  
Belief Model ◽  
Racial Ethnic

BACKGROUND The prevalence of depression symptoms in the United States is >3 times higher mid–COVID-19 versus pre-pandemic. Racial/ethnic differences in mindsets around depression and the potential impact of the COVID-19 pandemic are not well characterized. OBJECTIVE To describe attitudes, mindsets, key drivers, and barriers related to depression pre– and mid–COVID-19 by race/ethnicity using digital conversations about depression mapped to health belief model (HBM) concepts. METHODS Advanced search, data extraction, and AI-powered tools were used to harvest, mine, and structure open-source digital conversations of US adults who engaged in conversations about depression pre– (February 1, 2019-February 29, 2020) and mid–COVID-19 pandemic (March 1, 2020-November 1, 2020) across the internet. Natural language processing, text analytics, and social data mining were used to categorize conversations that included a self-identifier into racial/ethnic groups. Conversations were mapped to HBM concepts (ie, perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and self-efficacy). Results are descriptive in nature. RESULTS Of 2.9 and 1.3 million relevant digital conversations pre– and mid–COVID-19, race/ethnicity was determined among 1.8 million (62%) and 979,000 (75%) conversations pre– and mid–COVID-19, respectively. Pre–COVID-19, 1.3 million conversations about depression occurred among non-Hispanic Whites (NHW), 227,200 among Black Americans (BA), 189,200 among Hispanics, and 86,800 among Asian Americans (AS). Mid–COVID-19, 736,100 conversations about depression occurred among NHW, 131,800 among BA, 78,300 among Hispanics, and 32,800 among AS. Conversations among all racial/ethnic groups had a negative tone, which increased pre– to mid–COVID-19; finding support from others was seen as a benefit among most groups. Hispanics had the highest rate of any racial/ethnic group of conversations showing an avoidant mindset toward their depression. Conversations related to external barriers to seeking treatment (eg, stigma, lack of support, and lack of resources) were generally more prevalent among Hispanics, BA, and AS than among NHW. Being able to benefit others and building a support system were key drivers to seeking help or treatment for all racial/ethnic groups. CONCLUSIONS Applying concepts of the HBM to data on digital conversation about depression allowed organization of the most frequent themes by race/ethnicity. Individuals of all groups came online to discuss their depression. There were considerable racial/ethnic differences in drivers and barriers to seeking help and treatment for depression pre– and mid–COVID-19. Generally, COVID-19 has made conversations about depression more negative, and with frequent discussions of barriers to seeking care. These data highlight opportunities for culturally competent and targeted approaches to address areas amenable to change that might impact the ability of people to ask for or receive mental health help, such as the constructs that comprise the HBM.

Multiculturalism and Canadian Psychiatry: Opportunities and Challenges

1986 ◽  
Vol 31 (7) ◽  
pp. 681-690 ◽  
Author(s):  
Tsung-Yi Lin
Keyword(s):  
Mental Disorders ◽  
Ethnic Groups ◽  
Ethnic Differences ◽  
National Policy ◽  
Cultural Factors ◽  
Cultural Relativism ◽  
Cultural Relevancy ◽  
Research Activities ◽  
Causative Factors ◽  
Scientific Attention

In this lecture, the writer calls the attention of Canadian psychiatrists to the unparalleled opportunities the national policy of multiculturalism has for clinical and research activities. Using illustrations from three important fields in psychiatry — epidemiology, psychopharmacology and psychotherapy, he points out the roles socio-cultural factors play in generating ethnic differences which deserve to be given serious scientific attention for both the understanding of causative factors and the treatment of mental disorders. He emphasizes that medical universalism and ethnocentricism have no place in Canadian psychiatry, and that the next phase of Canadian psychiatry should focus on cultural relevancy based on cultural relativism and equal participation of all cultures and ethnic groups.

scholarly journals Racial/ethnic differences in inpatient mortality and use of institutional postacute care following subarachnoid hemorrhage

2013 ◽  
Vol 119 (6) ◽  
pp. 1627-1632 ◽  
Author(s):  
Blessing N. R. Jaja ◽  
Gustavo Saposnik ◽  
Rosane Nisenbaum ◽  
Benjamin W. Y. Lo ◽  
Tom A. Schweizer ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Ethnic Groups ◽  
Ethnic Differences ◽  
Institutional Care ◽  
Inpatient Mortality ◽  
Risk Of Death ◽  
The Us ◽  
Hispanic Patients ◽  
Racial Ethnic ◽  
White Patients

Object The goal of this study was to determine racial/ethnic differences in inpatient mortality rates and the use of institutional postacute care following subarachnoid hemorrhage (SAH) in the US. Methods A cross-sectional study of hospital discharges for SAH was conducted using the Nationwide Inpatient Sample for the years 2005–2010. Discharges with a principal diagnosis of SAH were identified and abstracted using the appropriate ICD-9-CM diagnostic code. Racial/ethnic groups were defined as white, black, Hispanic, Asian/Pacific Islander (API), and American Indian. Multinomial logistic regression analyses were performed comparing racial/ethnic groups with respect to the primary outcome of risk of in-hospital mortality and the secondary outcome of likelihood of discharge to institutional care. Results During the study period, 31,631 discharges were related to SAH. Race/ethnicity was a significant predictor of death (p = 0.003) and discharge to institutional care (p ≤ 0.001). In the adjusted analysis, compared with white patients, API patients were at higher risk of death (OR 1.34, 95% CI 1.13–1.59) and Hispanic patients were at lower risk of death (OR 0.84, 95% CI 0.72–0.97). The likelihood of discharge to institutional care was statistically similar between white, Hispanic, API, and Native American patients. Black patients were more likely to be discharged to institutional care compared with white patients (OR 1.27, 95% CI 1.14–1.40), but were similar to white patients in the risk of death. Conclusions Significant racial/ethnic differences are present in the risk of inpatient mortality and discharge to institutional care among patients with SAH in the US. Outcome is likely to be poor among API patients and best among Hispanic patients compared with other groups.

scholarly journals Ecology of the Anthropocene signals hope for consciously managing the planetary ecosystem

2021 ◽  
Vol 118 (28) ◽  
pp. e2024150118
Author(s):  
Clarence Lehman ◽  
Shelby Loberg ◽  
Michael Wilson ◽  
Eville Gorham
Keyword(s):  
Population Growth ◽  
Cultural Evolution ◽  
Human Population ◽  
Human Populations ◽  
Present Moment ◽  
Minimal Set ◽  
The Past ◽  
Food Species ◽  
Large Predators ◽  
Population Numbers

Human populations have grown to such an extent that our species has become a dominant force on the planet, prompting geologists to begin applying the term Anthropocene to recognize the present moment. Many approaches seek to explain the past and future of human population growth, in the form of narratives and models. Some of the most influential models have parameters that cannot be precisely known but are estimated by expert opinion. Here we apply a unified model of ecology to provide a macroscale summary of the net effects of many microscale processes, using a minimal set of parameters that can be known. Our models match estimates of historic and prehistoric global human population numbers and provide predictions that correspond to some of the more complicated current models. In addition to fitting the data well they reveal that, amidst enormous complexity in our human and prehuman past, three key ecological discontinuities have occurred in turn: 1) becoming dominant competitors of large predators rather than their prey, 2) becoming mutualists with food species rather than acting as predators upon them, and 3) changing from a regime of uncontrolled population growth to one of controlled fertility instead. All three processes have been interlinked with cultural evolution and all three ushered in developments of the Anthropocene. Understanding the trajectories that have delivered us to this stage can help guide prudent paths into the future.

scholarly journals Differences in Subjective Memory Impairment, Depressive Symptoms, Sleep, and Physical Activity in African American and Asian American Elderly

2021 ◽  
Vol 11 (9) ◽  
pp. 1155
Author(s):  
Minsun Lee ◽  
Jin-Hyeok Nam ◽  
Elizabeth Yi ◽  
Aisha Bhimla ◽  
Julie Nelson ◽  
...  
Keyword(s):  
Physical Activity ◽  
Depressive Symptoms ◽  
Ethnic Groups ◽  
Ethnic Differences ◽  
Asian American ◽  
Memory Impairment ◽  
Subjective Memory ◽  
Subjective Memory Impairment ◽  
Negative Health Outcomes ◽  
Racial Ethnic

Background: Subjective memory impairment (SMI) is associated with negative health outcomes including mild cognitive impairment and Alzheimer’s disease. However, ethnic differences in SMI and disparities in risk factors associated with SMI among minority populations are understudied. The study examined the ethnic differences in SMI, whether SMI was associated with depressive symptoms, sleep, and physical activity (PA), and whether the associations vary across racial/ethnic groups. Methods: Participants included 243 African and Asian Americans (including Chinese, Vietnamese, and Korean Americans) aged 50 or older. Demographic information, SMI, depressive symptoms, daily sleeping hours, and PA levels were assessed. Results: Vietnamese Americans reported the highest SMI score. Depressive symptoms, sleeping hours, and PA levels were significantly associated with SMI. Depressive symptoms were the only significant factor across all ethnic groups. Significant interaction effects were found between ethnicity and health behaviors in predicting SMI. In particular, Vietnamese American participants with greater depressive symptoms and physical inactivity were significantly more likely to experience SMI compared to other ethnic groups Conclusions: Our findings demonstrate ethnic differences in SMI and its association with depressive symptoms, sleep, and PA, which highlight the importance of considering the unique cultural and historical backgrounds across different racial/ethnic groups when examining cognitive functioning in elderly.

Sign in / Sign up

Export Citation Format

Share Document