Large haploblocks underlie rapid adaptation in the invasive weed Ambrosia artemisiifolia.

Adaptation is the central feature and leading explanation for the evolutionary diversification of life. Adaptation is also notoriously difficult to study in nature, owing to its complexity and logistically prohibitive timescale. Here, we leverage extensive contemporary and historical collections of Ambrosia artemisiifolia-an aggressively invasive weed and primary cause of pollen-induced hayfever-to track the phenotypic and genetic causes of recent local adaptation across its native and invasive ranges in North America and Europe, respectively. Large haploblocks-indicative of chromosomal inversions-contain a disproportionate share (26%) of genomic regions conferring parallel adaptation to local climates between ranges, are associated with rapidly adapting traits, and exhibit dramatic frequency shifts over space and time. These results highlight the importance of large-effect standing variants in rapid adaptation, which have been critical to A. artemisiifolia's global spread across vast climatic gradients.

Network Autocorrelation of Perceived Physical Activity Skill Competence Among Adolescents at a Summer Care Program: A Pilot Study.

PURPOSE: This study investigates the possible association between adolescent friendship networks and perceived physical activity skill competence in a summer care program. DESIGN: Adolescents participated in researcher-administered surveys at the start (T1) and end (T2) of summer. SETTING: Adolescents at a Boys & Girls Club were sampled. SAMPLE: Adolescents (age 8-12) completed researcher-administered surveys at T1 (n = 100; µ age = 9.9 years; 47% male; 55% Black) and T2 (n = 77; µ age = 9.8 years; 51% male; 49% Black). MEASURES: Perceived skill competence was measured by asking adolescents to rate how good they felt they were at physical activity at the club. Adolescents were also asked to provide names of up to 5 peers whom they hung around with, talked to, and did things with the most while at the club. ANALYSIS: Linear network autocorrelation models were used to determine network effects or clustering of perceived physical activity skill competence within the club. RESULTS: There were significant network effects for adolescent perceived skill competency scores at T1 (ß = 0.05, p < 0.01) and T2 (ß = 0.05, p = 0.02), indicating adolescent perceived skill competence scores were associated with those of their friends. CONCLUSIONS: Practitioners may wish to encourage the use of group or collaborative skill competency improvement activities as well as possibly pairing adolescents with differing skill competencies to foster improvement and possible diffusion of perceived skill competency.