Rapid phenotypic evolution with shallow genomic differentiation during early stages of high elevation adaptation in Eurasian Tree Sparrows

Known as the ‘third polar region’, the Qinghai-Tibet Plateau represents one of the harshest highland environments in the world and yet a number of organisms thrive there. Previous studies of birds, animals and humans have focused on well-differentiated populations in later stages of phenotypic divergence. The adaptive processes during the initial phase of highland adaptation remain poorly understood. We studied a human commensal, the Eurasian Tree Sparrow, which has followed human agriculture to the Qinghai-Tibet Plateau. Despite strong phenotypic differentiation at multiple levels, in particular in muscle-related phenotypes, highland and lowland populations show shallow genomic divergence and the colonization event occurred within the past few thousand years. In a one-month acclimation experiment investigating phenotypic plasticity, we exposed adult lowland tree sparrows to a hypoxic environment and did not observe muscle changes. Through population genetic analyses, we identified a signature of polygenic adaptation, whereby shifts in allele frequencies are spread across multiple loci, many of which are associated with muscle-related processes. Our results reveal a case of positive selection in which polygenic adaptation appears to drive rapid phenotypic evolution, shedding light on early stages of adaptive evolution to a novel environment.     

Gender,text, and discussion: Examining intellectual safety in the science classroom

It is clear from the extant literature that gender inequities exist in a myriad of ways in science classrooms. Past research, however, has been conducted solely from researchers' observations and has neglected to investigate students' awareness of and reactions to their own experiences. Hence, this study focused on students' perceptions of gender differences in instructional activity and talk about that activity in physics and honors physics classes. Data analysis showed that although teachers may be unaware of gender inequities, students of both sexes are not unaware of such inequities. Females explained their fears of offering their opinions and participating in activities like labs and small-group or whole-class discussions. Differential language patterns were found for males and females, particularly when discussion was structured and rewarded for refutation. Explanations are offered for these disparities and suggestions are given for addressing gender bias in science classrooms. It has been well documented that science classrooms are not gender fair (Bazler & Simonis, 1991; Bianchini, 1993; Tobin, 1988). Teachers, texts, and the forms of instruction they perpetuate contribute to gender inequities in science instruction. For example, research tracing changes in science textbooks over time has shown that current texts have failed to eliminate barriers to women in science (Bianchini, 1993). Science textbooks are criticized for their unequal treatment of genders, with illustrations, photos, and texts of males far outnumbering those of females, despite the approximate 50/50 male/female ratio of our population (Bazler & Simonis, 1991). In addition to the proclivity of science textbooks to favor males, researchers speculate that the tendency for boys to achieve higher than girls in science may be a result of more opportunity to engage in academic tasks (Tobin & Garnett, 1987). Their behavior shows that teachers have differential expectations for students' responses in activities like teacher-led discussion. In teacher-led, whole-class discussion, boys are spoken to more frequently and are asked more higher-order questions (Becker, 1991; Hall & Sadler, 1982). Teachers in science classrooms elaborate more on males' responses than females' responses in large-group discussion of scientific concepts (Jones & Wheatley, 1990). © 1996 John Wiley & Sons, Inc.     

Student performances on the science processes of recording data,analyzing data,drawing conclusions,and providing evidence

The National Committee on Science Education Standards and Assessment (1994 draft) viewed several science processes as important to an understanding of science as inquiry: formulating usable questions, planning experiments, conducting systematic observations, interpreting and analyzing data, drawing conclusions, communicating, and coordinating and implementing a full investigation. This study is one of three undertaken to develop research rubrics for a performance assessment of science processes and to evaluate seventh-grade science students' ability to perform them. Specifically, this article focuses on the processes of recording data, analyzing data, drawing conclusions, and providing evidence. A total of 364 students field tested the Alternative Assessment of Science Process Skills. Their responses were used to develop a research rubric, and then this rubric was used to determine response patterns that could inform both instruction and assessment of science process skills. Only 61% of students performed the activity and recorded data successfully. Sixty-nine percent of students did not attend to the hypothesis in drawing their conclusions. Eighty-one percent did not provide specific evidence for their conclusions. These results were discussed in light of relevant theories and models as well as their implications for instruction and assessment. © 1996 John Wiley & Sons, Inc.     

Rhetoric and reality in science performance assessments: An update

This article addresses the rhetoric of performance assessment with research on important claims about science performance assessments. We found the following: (a) Concepts and terminology used to refer to performance assessments often were not consistent within and across researchers, educators, and policy-makers. (b) Performance assessments are highly sensitive not only to the tasks and the occasions sampled, but also to the method (e.g., hands-on, computer simulation) used to measure performance. (c) Performance assessments do not necessarily tap higher-order thinking, especially when they are poorly designed. (d) Performance assessments are expensive to develop and use: technology is needed for developing these assessments in an efficient way. (e) Performance assessments do not necessarily have the expected positive impact on teachers' teaching and students' understanding. (f) If teachers are to use performance assessments in their classrooms, they need professional development to help them construct the necessary knowledge and skills. This article attempts to address some of these realities by presenting a conceptual framework that might guide the development and the evaluation of performance assessments, as well as steps that might be taken to create a performance assessment technology and develop teacher inservice programs. © 1996 John Wiley & Sons, Inc.     

Teachers' attitudes and policies regarding play in elementary schools

Research and theory concerning the value of play for children's development as well as current factors reducing the amount of play time that children experience are discussed. To ascertain play opportunities occurring in the schools, teachers' attitudes toward play, and provision of play for children in grades 1–6 were surveyed. The amount of recess time provided ranged from 0 to 65 min., with a mean of almost 19 min. Findings indicated that teachers from rural areas provided more play time than teachers from suburban areas, who in turn provided more play time than teachers in urban areas. Further, the amount of play time provided was influenced by the teachers' attitudes. That is, teachers who indicated generally positive attitudes toward play tended to allot more time for play in school. However, teachers from upper grade levels, who were more likely to perceive greater pressure to provide highly structured academic instructional programs, tended to de-emphasize the role and value of play and in turn allotted less time for play in school. The results of the present investigation demonstrate that children who are given less recess time are also likely to have teachers who report less positive attitudes toward play. It is recommended that school psychologists be aware of the adverse impact that restricted play opportunities may have on children's development. © 1996 John Wiley & Sons, Inc.