Motivation for Physical Activity as a Key Determinant of Sedentary Behavior Among Postsecondary Students.

It is known that the transition to adulthood represents a critical period of life when acquiring healthy behaviors can influence lifestyle and health throughout adulthood. Given the importance of the consequences of a sedentary lifestyle, identifying influence factors is key to improving healthy behaviors. The objective of this study is to explore the role of postsecondary students' motivation toward physical activity in the association with their screen time and out-of-school physical activity practice. A total of 1522 postsecondary students (90% were aged 17-20 years) recruited from 17 postsecondary institutions completed the self-reported questionnaire during course time. Multivariate linear regression was used to assess the association between motivation to move including additional predictors of behavior such as intention and tendency to self-activate and self-reported screen time and physical activity controlling for age and sex. Motivation including all 3 motivational variables (interest, utility, competence) was negatively associated with screen time, b = -0.498 (95% CI between -0.635 and -0.361) and positively associated with moderate-to-vigorous physical activity, b = 133.986, (95% CI between 102.129 and 165.843). Of the 3 motivational variables, interest had the strongest negative association with screen time, b = -0.434 (95% CI between -0.551 and -0.317), and the strongest positive association with physical activity, b = 113.671, (95% CI between 86.396 and 140.946). These findings indicate that the motivation of postsecondary students toward physical activity significantly influences their behaviors, including screen time and physical activity engagement.

New insight into the global record of the Ediacaran tubular morphotype: a common solution to early multicellularity.

The tubular morphogroup is a common component of Earth's first complex, multicellular communities-the Ediacaran biota-and offers valuable insight into biological traits that are fundamental to animal life because they have intriguing links to metazoan phyla and are highly abundant in Ediacaran ecosystems. Biomineral tubes (e.g. Cloudina) are well described from the Nama assemblage (~550-538 Myr), yielding a relatively detailed understanding of this subset of the morphogroup. Conversely, the non-biomineral tubular taxa of the Nama assemblage, as well as of the older White Sea assemblage (~560-550 Myr), are poorly understood. As a result, the variability of characters that define non-biomineral tubular organisms is unknown and their diversity dynamics throughout the terminal Ediacaran are unconstrained. To test hypotheses related to the diversity, morphological variability and temporal distribution of non-biomineral tubes, a comprehensive database of non-biomineral Ediacaran tubular taxa was compiled. Results demonstrate previously unrecognized morphological disparity in the non-biomineral tubular morphogroup and reveal that it comprises a higher number of genera than all other non-tubular morphogroups in the White Sea and the Nama. Thus, it illustrates that a tubular form dominated Ediacaran ecosystems for considerably longer than previously appreciated and, importantly, was the most common solution to early multicellularity.

Environmental drivers of the first major animal extinction across the Ediacaran White Sea-Nama transition.

The Ediacara Biota-the oldest communities of complex, macroscopic fossils-consists of three temporally distinct assemblages: the Avalon (ca. 575-560 Ma), White Sea (ca. 560-550 Ma), and Nama (ca. 550-539 Ma). Generic diversity varies among assemblages, with a notable decline at the transition from White Sea to Nama. Preservation and sampling biases, biotic replacement, and environmental perturbation have been proposed as potential mechanisms for this drop in diversity. Here, we compile a global database of the Ediacara Biota, specifically targeting taphonomic and paleoecological characters, to test these hypotheses. Major ecological shifts in feeding mode, life habit, and tiering level accompany an increase in generic richness between the Avalon and White Sea assemblages. We find that ∼80% of White Sea taxa are absent from the Nama interval, comparable to loss during Phanerozoic mass extinctions. The paleolatitudes, depositional environments, and preservational modes that characterize the White Sea assemblage are well represented in the Nama, indicating that this decline is not the result of sampling bias. Counter to expectations of the biotic replacement model, there are minimal ecological differences between these two assemblages. However, taxa that disappear exhibit a variety of morphological and behavioral characters consistent with an environmentally driven extinction event. The preferential survival of taxa with high surface area relative to volume may suggest that this was related to reduced global oceanic oxygen availability. Thus, our data support a link between Ediacaran biotic turnover and environmental change, similar to other major mass extinctions in the geologic record.

Biostratinomy of the Ediacara Member (Rawnsley Quartzite, South Australia): implications for depositional environments, ecology and biology of Ediacara organisms.

The Precambrian Ediacara Biota-Earth's earliest fossil record of communities of macroscopic, multicellular organisms-provides critical insights into the emergence of complex life on our planet. Excavation and reconstruction of nearly 300 m2 of fossiliferous bedding planes in the Ediacara Member of the Rawnsley Quartzite, at the National Heritage Ediacara fossil site Nilpena in South Australia, have permitted detailed study of the sedimentology, taphonomy and palaeoecology of Ediacara fossil assemblages. Characterization of Ediacara macrofossils and textured organic surfaces at the scale of facies, bedding planes and individual specimens has yielded unprecedented insight into the manner in which the palaeoenvironmental settings inhabited by Ediacara communities-particularly hydrodynamic conditions-influenced the aut- and synecology of Ediacara organisms, as well as the morphology and assemblage composition of Ediacara fossils. Here, we describe the manner in which environmental processes mediated the development of taphofacies hosting Ediacara fossil assemblages. Using two of the most common Ediacara Member fossils, Arborea and Dickinsonia, as examples, we delineate criteria that can be used to distinguish between ecological, environmental and biostratinomic signals and reconstruct how interactions between these processes have distinctively shaped the Ediacara fossil record.