American Association for the Advancement of Science

About: American Association for the Advancement of Science is a nonprofit organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Science education & Government. The organization has 353 authors who have published 897 publications receiving 18841 citations. The organization is also known as: AAAS.

Local versus Generalized Phenotypes in Two Sympatric Aurelia Species: Understanding Jellyfish Ecology Using Genetics and Morphometrics

Abstract: For individuals living in environmentally heterogeneous environments, a key component for adaptation and persistence is the extent of phenotypic differentiation in response to local environmental conditions. In order to determine the extent of environmentally induced morphological variation in a natural population distributed along environmental gradients, it is necessary to account for potential genetic differences contributing to morphological differentiation. In this study, we set out to quantify geographic morphological variation in the moon jellyfish Aurelia exposed at the extremes of a latitudinal environmental gradient in the Gulf of Mexico (GoM). We used morphological data based on 28 characters, and genetic data taken from mitochondrial cytochrome oxidase I (COI) and nuclear internal transcribed spacer 1 (ITS-1). Molecular analyses revealed the presence of two genetically distinct species of Aurelia co-occurring in the GoM: Aurelia sp. 9 and Aurelia c.f. sp. 2, named for its divergence from (for COI) and similarity to (for ITS-1) Aurelia sp. 2 (Brazil). Neither species exhibited significant population genetic structure between the Northern and the Southeastern Gulf of Mexico; however, they differed greatly in the degree of geographic morphological variation. The morphology of Aurelia sp. 9 exhibited ecophenotypic plasticity and varied significantly between locations, while morphology of Aurelia c.f. sp. 2 was geographically invariant (i.e., canalized). The plastic, generalist medusae of Aurelia sp. 9 are likely able to produce environmentally-induced, "optimal" phenotypes that confer high relative fitness in different environments. In contrast, the non-plastic generalist individuals of Aurelia c.f. sp. 2 likely produce environmentally-independent phenotypes that provide the highest fitness across environments. These findings suggest the two Aurelia lineages co-occurring in the GoM were likely exposed to different past environmental conditions (i.e., different selective pressures) and evolved different strategies to cope with environmental variation. This study highlights the importance of using genetics and morphometric data to understand jellyfish ecology, evolution and systematics.

Genome mapping of quantitative trait loci (QTL) controlling domestication traits of intermediate wheatgrass (Thinopyrum intermedium)

Abstract: Allohexaploid (2n = 6x = 42) intermediate wheatgrass (Thinopyrum intermedium), abbreviated IWG, is an outcrossing perennial grass belonging to the tertiary gene pool of wheat. Perenniality would be valuable option for grain production, but attempts to introgress this complex trait from wheat-Thinopyrum hybrids have not been commercially successful. Efforts to breed IWG itself as a dual-purpose forage and grain crop have demonstrated useful progress and applications, but grain yields are significantly less than wheat. Therefore, genetic and physical maps have been developed to accelerate domestication of IWG. Herein, these maps were used to identify quantitative trait loci (QTLs) and candidate genes associated with IWG grain production traits in a family of 266 full-sib progenies derived from two heterozygous parents, M26 and M35. Transgressive segregation was observed for 17 traits related to seed size, shattering, threshing, inflorescence capacity, fertility, stem size, and flowering time. A total of 111 QTLs were detected in 36 different regions using 3826 genotype-by-sequence markers in 21 linkage groups. The most prominent QTL had a LOD score of 15 with synergistic effects of 29% and 22% over the family means for seed retention and percentage of naked seeds, respectively. Many QTLs aligned with one or more IWG gene models corresponding to 42 possible domestication orthogenes including the wheat Q and RHT genes. A cluster of seed-size and fertility QTLs showed possible alignment to a putative Z self-incompatibility gene, which could have detrimental grain-yield effects when genetic variability is low. These findings elucidate pathways and possible hurdles in the domestication of IWG.

Critical Mass Revisited Learning Lessons From Research on Diversity in STEM Fields

Abstract: –178 DOI: 10.3102/0013189X13486763 © 2013 AERA. http://er.aera.net 176 EDUCATIONAL RESEARCHER Numerous legal scholars and social scientists have highlighted the ways in which research has informed judicial decision making (e.g., Dunn & West, 2008; Morgan & Pullin, 2010; Moses & Marin, 2006). Because, in part, of convincing empirical research presented in several landmark cases (e.g., Grutter v. Bollinger, 2003; Parents Involved in Community Schools v. Seattle School District No. 1, 2007), the consideration of race in educational policies has been deemed permissible, albeit in limited, narrowly tailored ways. Grutter also represented an affirmation of the importance of research for social scientists whose work provided empirical evidence of the educational benefits of diversity and the importance of a “critical mass” of underrepresented students, which served as a basis for the Court’s decision. Although the Court upheld the University of Michigan Law School’s admissions policy in Grutter, the opinion of the Court also stated the expectation that race would no longer need to be considered in a generation’s time. However, as evidenced by the oral arguments of Fisher v. University of Texas, which came just 9 years after Grutter, time may be running short for race-conscious admissions. In the Fisher oral arguments, the questions did not necessarily focus on diversity—defined as a “critical mass” of underrepresented students—as a compelling interest. Instead, many of the concerns (most often voiced by the Court’s more conservative Justices) centered around two questions: (a) Can a critical mass of racial/ethnic minority members be achieved without considering race? and (b) How will we know that a critical mass has been achieved and, thus, that the endpoint for the consideration of race has been reached? Both of these questions concern the narrow tailoring of holistic admissions policies in which race is considered as a factor (see footnote 2 in Garces, this issue, for further discussion of narrow tailoring). The intense focus on these two questions suggests that we, as social scientists, need to be more effective and strategic in our efforts to communicate findings from existing research on the effects of race-neutral policies on access and success for underrepresented populations. We should be prepared as well to conduct further inquiry into what the indicators of a critical mass are across a range of institutional contexts. As scholar-advocates whose previous work has focused on broadening participation in science, technology, engineering, mathematics (STEM), and related fields, we argue that social scientists ought to look to the vast STEM education research literature to begin the task of empirically investigating the questions raised in the Fisher case. In the analysis that follows, we provide our answers to the two questions above, based on research and evaluation of current programs and institutional efforts aimed at broadening participation in STEM. With regard to the first question, whether a critical mass can be achieved without considering race, “we doubt it.” There have been numerous efforts to find proxies for race such as socioeconomic status (SES) or first-generation status. Across higher education as well as within STEM, these proxies have not represented race and ethnicity. In STEM, this is evidenced by the declines in underrepresented minority student enrollment in STEM graduate degree programs that followed the implementation of raceblind admissions policies, and a failure to regain previous levels in the subsequent years (Garces, 2013; Malcom, Van Horne, Gaddy, & George, 1998). With regard to the second question, how can one know when a critical mass has been reached, “when diversity is selfsustaining.” Decades of scholarly research and programmatic evaluations aimed at understanding the factors that contribute to diversified STEM programs indicate that sustainable diversity results from environmental changes—that is, changes in culture, curricula, and instruction; quality and quantity of supportive practices; and faculty behaviors, attitudes, and expectations)— that support the success of all students (see Chubin, DePass, & Blockus, 2009; DePass & Chubin, 2008; Fox, Sonnert, & Nikiforova, 2009; Margolis & Fisher, 2002; Maton & Hrabowski, 2004).