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1.
CBE Life Sci Educ ; 23(2): ar23, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38728228

ABSTRACT

In response to unwaveringly high attrition from STEM pathways, STEM Intervention Programs (SIPs) support STEM students in effort to increase retention. Using mixed methods (survey and focus groups), we studied students at one university who were either supported or unsupported by SIPs to understand how students may differ in experiences believed to contribute to STEM persistence. We evaluated: sense of belonging, scientific self-efficacy, scientific community values, scientific identity, and STEM involvement. The enrollment status of students two and a half years postsurvey was also tracked. SIP students reported significantly higher science identity and sense of belonging and were more involved in STEM-related activities than counterparts unsupported by SIPs. Differences in these measures were correlated with race/ethnicity, college generation status, and age. Notably, SIP students had higher odds of persisting in STEM than students not supported by SIPs. Focus group data provide additional meaning to the measured survey constructs and revealed nuanced qualitative differences between SIP and non-SIP student experiences. Overall, being involved in a SIP at our institution trends positively with theoretical models that explain STEM student persistence. SIPs have the potential to provide and/or facilitate meaningful and critical support, and students without those intentional supports may be left behind.


Subject(s)
Science , Students , Humans , Male , Female , Science/education , Young Adult , Focus Groups , Adult , Universities , Technology/education , Engineering/education , Surveys and Questionnaires , Self Efficacy , Mathematics/education
2.
CBE Life Sci Educ ; 22(4): es4, 2023 12.
Article in English | MEDLINE | ID: mdl-37816213

ABSTRACT

Course-based undergraduate research experiences (CUREs) offer an expanding avenue to engage students in real-world scientific practices. Increasingly, CUREs are instructed by graduate teaching assistants (TAs), yet TAs may be underprepared to facilitate and face unique barriers when teaching CUREs. Consequently, unless TAs are provided professional development (PD) and resources to teach CUREs effectively, they and their students may not reap the assumed benefits of CURE instruction. Here, we describe three perspectives - that of the CURE TA, the CURE designer/facilitator, and the CURE student - that are collectively intended to inform the development of tentative components of CURE TA PD. We compare these perspectives to previous studies in the literature in an effort to identify commonalities across all sources and offer potential insights for advancing CURE TA PD efforts across a diversity of institutional environments. We propose that the most effective CURE TA PD programs will promote the use of CURE-specific instructional strategies as benchmarks for guiding change in teaching practices and should focus on three major elements: 1) enhancement of research and teaching acumen, 2) development of effective and inclusive mentoring practices, and 3) identification and understanding of the factors that make CUREs a unique learning experience.


Subject(s)
Biological Science Disciplines , Students , Humans , Learning , Curriculum , Mentors
3.
PLoS One ; 17(9): e0275313, 2022.
Article in English | MEDLINE | ID: mdl-36166457

ABSTRACT

To expose all undergraduate science students to the benefits of participating in research, many universities are integrating course-based undergraduate research experiences (CUREs) into their introductory biology laboratory curriculum. At large institutions, the bulk of introductory labs are instructed by graduate teaching assistants (GTAs). Graduate students, who are often teachers and researchers in training, may vary in their capacity to effectively teach undergraduates via the CURE model. To explore variation in GTA teaching and the subsequent outcomes for students, we used a case study research design at one institution where introductory biology students participate in GTA-taught CURE lab sections. We used multiple data sources, including in-class focus groups, worksheets, and surveys to explore student perceptions of the GTA-led CURE. Students perceived variation both in the ability of their GTAs to create a supportive and comfortable learning environment, and in the instructional priorities of their GTAs. We also compared student and GTA perspectives of student engagement with research elements in the CURE. While GTAs were divided in their perceptions of whether the CURE provided students with the opportunity to experience the element of relevant discovery, most students-regardless of their GTA-did not perceive that relevant discovery was emphasized in the CURE. Finally, individual GTAs seemed to influence how students perceived why they were participating in the CURE. These data imply that students in CUREs may have vastly different and potentially inequitable research experiences depending on their instructor.


Subject(s)
Learning , Students , Curriculum , Humans , Laboratories , Universities
4.
CBE Life Sci Educ ; 21(3): ar57, 2022 09.
Article in English | MEDLINE | ID: mdl-35998160

ABSTRACT

Community colleges expand access to higher education and play a key role in efforts to increase and diversify the future science, technology, engineering, and mathematics (STEM) workforce. While community colleges increase access to higher education and millions of students attend them for some portion of their education, the experiences of transfer students remain relatively understudied. Transferring during an academic journey can compound the barriers that students already face when pursuing a STEM degree. This study uses Schlossberg's model for analyzing human adaptation to transition to understand how STEM community college transfer students navigate and adapt to the 4-year university. Five semistructured focus groups were conducted with STEM community college transfer students attending an urban university. Analysis of the focus groups resulted in a new model: the amended model of adaptation to transfer transition, or AMATT, which illustrates various factors that played a role in STEM community college transfer students' adaptation a university. Analyses illumined two broad pathways that students tend to diverge into during their transitions-thriving or simply surviving. This work provides a framework for understanding factors influencing the transfer process and ideally will inform institutions and students as they consider maximal transfer student success.


Subject(s)
Engineering , Students , Engineering/education , Humans , Mathematics , Technology/education , Universities
5.
J Microbiol Biol Educ ; 23(1)2022 Jan.
Article in English | MEDLINE | ID: mdl-34970392

ABSTRACT

Measuring students' perceptions of active learning activities may provide valuable insight into their engagement and subsequent performance outcomes. A recently published measure, the Assessing Student Engagement in Class Tool (ASPECT), was developed to assess student perceptions of various active learning environments. As such, we sought to use this measure in our courses to assess the students' perceptions of different active learning environments. Initial results analyzed with confirmatory factor analysis (CFA) indicated that the ASPECT did not function as expected in our active learning environments. Therefore, before administration within an introductory biology course that incorporated two types of active learning strategies, additional items were created and the wording of some original items were modified to better align with the structure of each strategy, thereby producing two modified ASPECT (mASPECT) versions. Evidence of response process validity of the data collected was analyzed using cognitive interviews with students, while internal structure validity evidence was assessed through exploratory factor analysis (EFA). When data were collected after a "deliberative democracy" (DD) activity, 17 items were found to contribute to 3 factors related to 'personal effort', 'value of the environment', and 'instructor contribution'. However, data collected after a "clicker" day resulted in 21 items that contributed to 4 factors, 3 of which were similar to the DD activity, and a fourth was related to 'social influence'. Overall, these results suggested that the same measure may not function identically when used within different types of active learning environments, even with the same population, and highlights the need to collect data validity evidence when adopting and/or adapting measures.

6.
Ecol Evol ; 11(23): 16387-16408, 2021 Dec.
Article in English | MEDLINE | ID: mdl-34938443

ABSTRACT

Undergraduate field experiences (UFEs) are a prominent element of science education across many disciplines; however, empirical data regarding the outcomes are often limited. UFEs are unique in that they typically take place in a field setting, are often interdisciplinary, and include diverse students. UFEs range from courses, to field trips, to residential research experiences, and thereby have the potential to yield a plethora of outcomes for undergraduate participants. The UFE community has expressed interest in better understanding how to assess the outcomes of UFEs. In response, we developed a guide for practitioners to use when assessing their UFE that promotes an evidence-based, systematic, iterative approach. This essay guides practitioners through the steps of: identifying intended UFE outcomes, considering contextual factors, determining an assessment approach, and using the information gained to inform next steps. We provide a table of common learning outcomes with aligned assessment tools, and vignettes to illustrate using the assessment guide. We aim to support comprehensive, informed assessment of UFEs, thus leading to more inclusive and reflective UFE design, and ultimately improved student outcomes. We urge practitioners to move toward evidence-based advocacy for continued support of UFEs.

7.
CBE Life Sci Educ ; 20(4): ar66, 2021 12.
Article in English | MEDLINE | ID: mdl-34714689

ABSTRACT

Despite growing evidence of positive student outcomes from course-based undergraduate research experiences (CUREs), little consideration has been given to employing graduate teaching assistants (GTAs) as CURE instructors. GTAs may be novice researchers and/or teachers and likely vary in their interest in teaching a CURE. Guided by expectancy-value theory, we explored how GTAs' self-efficacy and values regarding teaching a CURE impact motivation and perceptions of their roles as CURE instructors. Using a multiple case study design, we interviewed nine GTAs who taught a network CURE at one research institution. Though most GTAs held a relatively high value for teaching a CURE for a range of reasons, some GTAs additionally perceived high costs associated with teaching the CURE. Through the interview data, we established three profiles to describe GTA perceptions of their role as CURE instructors: "Student Supporters," "Research Mentors," and "Content Deliverers." Those implementing GTA-led CUREs should consider that GTAs likely have different perceptions of both their role in the classroom and the associated costs of teaching a CURE. The variability in GTA perceptions of CUREs implies that undergraduate students of different GTAs are unlikely to experience the CURE equivalently.


Subject(s)
Mentors , Students , Humans , Perception , Self Efficacy
8.
Proc Biol Sci ; 288(1947): 20210119, 2021 03 31.
Article in English | MEDLINE | ID: mdl-33784868

ABSTRACT

The evolution of sustained plant-animal interactions depends critically upon genetic variation in the fitness benefits from the interaction. Genetic analyses of such interactions are limited to a few model systems, in part because genetic variation may be absent or the interacting species may be experimentally intractable. Here, we examine the role of sperm-dispersing microarthropods in shaping reproduction and genetic variation in mosses. We established experimental mesocosms with known moss genotypes and inferred the parents of progeny from mesocosms with and without microarthropods, using a pooled sequencing approach. Moss reproductive rates increased fivefold in the presence of microarthropods, relative to control mesocosms. Furthermore, the presence of microarthropods increased the total number of reproducing moss genotypes, and changed the rank-order of fitness of male and female moss genotypes. Interestingly, the genotypes that reproduced most frequently did not produce sporophytes with the most spores, highlighting the challenge of defining fitness in mosses. These results demonstrate that microarthropods provide a fitness benefit for mosses, and highlight the potential for biotic dispersal agents to alter fitness among moss genotypes.


Subject(s)
Bryophyta , Bryopsida , Animals , Bryophyta/genetics , Bryopsida/genetics , Female , Male , Reproduction
9.
CBE Life Sci Educ ; 20(1): ar10, 2021 03.
Article in English | MEDLINE | ID: mdl-33600220

ABSTRACT

Course-based undergraduate research experiences (CUREs) and inquiry-based curricula both expose students to the scientific process. CUREs additionally engage students in novel and scientifically relevant research, with the intention of providing an "authentic" research experience. However, we have little understanding of which course design elements impact students' beliefs that they are experiencing "authentic" research. We designed a study to explore introductory biology students' perceptions of research authenticity in CURE and inquiry classes. Using the Laboratory Course Assessment Survey, we found that students in CURE sections perceived higher levels of authentic research elements than students in inquiry-based sections. To identify specific factors that impact perceptions of research authenticity, we administered weekly reflection questions to CURE students. Coding of reflection responses revealed that experiences of failure, iteration, using scientific practices, and the relevant discoveries in their projects enhanced students' perceived authenticity of their research experiences. Although failure and iteration can occur in both CUREs and inquiry-based curricula, our findings indicate these experiences-in conjunction with the Relevant Discovery element of a CURE-may be particularly powerful in enhancing student perceptions of research authenticity in a CURE.


Subject(s)
Curriculum , Students , Emotions , Humans , Laboratories , Surveys and Questionnaires
10.
CBE Life Sci Educ ; 19(3): ar33, 2020 09.
Article in English | MEDLINE | ID: mdl-32720841

ABSTRACT

In a world of burgeoning societal issues, future scientists must be equipped to work interdisciplinarily to address real-world problems. To train undergraduate students toward this end, practitioners must also have quality assessment tools to measure students' ability to think within an interdisciplinary system. There is, however, a dearth of instruments that accurately measure this competency. Using a theoretically and empirically based model, we developed an instrument, the Interdisciplinary Science Rubric (IDSR), to measure undergraduate students' interdisciplinary science thinking. An essay assignment was administered to 102 students across five courses at three different institutions. Students' work was scored with the newly developed rubric. Evidence of construct validity was established through novice and expert response processes via semistructured, think-aloud interviews with 29 students and four instructors to ensure the constructs and criteria within the instrument were operating as intended. Interrater reliability of essay scores was collected with the instructors of record (κ = 0.67). An expert panel of discipline-based education researchers (n = 11) were consulted to further refine the scoring metric of the rubric. Results indicate that the IDSR produces valid data to measure undergraduate students' ability to think interdisciplinarily in science.


Subject(s)
Educational Measurement , Interdisciplinary Studies , Science , Data Interpretation, Statistical , Humans , Interdisciplinary Studies/statistics & numerical data , Reproducibility of Results , Science/education , Students
11.
CBE Life Sci Educ ; 19(1): ar8, 2020 03.
Article in English | MEDLINE | ID: mdl-32108558

ABSTRACT

A desired outcome of education reform efforts is for undergraduates to effectively integrate knowledge across disciplines in order to evaluate and address real-world issues. Yet there are few assessments designed to measure if and how students think interdisciplinarily. Here, a sample of science faculty were surveyed to understand how they currently assess students' interdisciplinary science understanding. Results indicate that individual writing-intensive activities are the most frequently used assessment type (69%). To understand how writing assignments can accurately assess students' ability to think interdisciplinarily, we used a preexisting rubric, designed to measure social science students' interdisciplinary understanding, to assess writing assignments from 71 undergraduate science students. Semistructured interviews were conducted with 25 of those students to explore similarities and differences between assignment scores and verbal understanding of interdisciplinary science. Results suggest that certain constructs of the instrument did not fully capture this competency for our population, but instead, an interdisciplinary framework may be a better model to guide assessment development of interdisciplinary science. These data suggest that a new instrument designed through the lens of this model could more accurately characterize interdisciplinary science understanding for undergraduate students.


Subject(s)
Interdisciplinary Studies , Science , Comprehension , Faculty , Humans , Science/education , Students , Universities
12.
R Soc Open Sci ; 6(11): 190744, 2019 Nov.
Article in English | MEDLINE | ID: mdl-31827828

ABSTRACT

Polar systems are experiencing rapid climate change and the high sensitivity of these Arctic and Antarctic ecosystems make them especially vulnerable to accelerated ecological transformation. In Antarctica, warming results in a mosaic of ice-free terrestrial habitats dominated by a diverse assemblage of cryptogamic plants (i.e. mosses and lichens). Although these plants provide key habitat for a wide array of microorganisms and invertebrates, we have little understanding of the interaction between trophic levels in this terrestrial ecosystem and whether there are functional effects of plant species on higher trophic levels that may alter with warming. Here, we used open top chambers on Fildes Peninsula, King George Island, Antarctica, to examine the effects of passive warming and moss species on the abiotic environment and ultimately on higher trophic levels. For the dominant mosses, Polytrichastrum alpinum and Sanionia georgicouncinata, we found species-specific effects on the abiotic environment, including moss canopy temperature and soil moisture. In addition, we found distinct shifts in sexual expression in P. alpinum plants under warming compared to mosses without warming, and invertebrate communities in this moss species were strongly correlated with plant reproduction. Mosses under warming had substantially larger total invertebrate communities, and some invertebrate taxa were influenced differentially by moss species. However, warmed moss plants showed lower fungal biomass than control moss plants, and fungal biomass differed between moss species. Our results indicate that continued warming may impact the reproductive output of Antarctic moss species, potentially altering terrestrial ecosystems dynamics from the bottom up. Understanding these effects requires clarifying the foundational, mechanistic role that individual plant species play in mediating complex interactions in Antarctica's terrestrial food webs.

13.
CBE Life Sci Educ ; 18(2): es3, 2019 06.
Article in English | MEDLINE | ID: mdl-31120394

ABSTRACT

An expanded investment in interdisciplinary research has prompted greater demands to integrate knowledge across disciplinary boundaries. Vision and Change similarly made interdisciplinary expectations a key competency for undergraduate biology majors; however, we are not yet synchronized on the meaning of interdisciplinarity, making this benchmark difficult to meet and assess. Here, we discuss aspects of interdisciplinarity through a historical lens and address various institutional barriers to interdisciplinary work. In an effort to forge a unified path forward, we provide a working definition of interdisciplinary science derived from both the perspectives of science faculty members and scientific organizations. We leveraged the existing literature and our proposed definition to build a conceptual model for an Interdisciplinary Science Framework to be used as a guide for developing and assessing interdisciplinary efforts in undergraduate science education. We believe this will provide a foundation from which the community can develop learning outcomes, activities, and measurements to help students meet the Vision and Change core competency of "tapping into the interdisciplinary nature of science."


Subject(s)
Interdisciplinary Studies , Students , Faculty , Humans , Learning
14.
CBE Life Sci Educ ; 18(1): ar3, 2019 03.
Article in English | MEDLINE | ID: mdl-30681902

ABSTRACT

Embedding active learning is a common mechanism for meeting science, technology, engineering, and mathematics (STEM) education reform goals. Researchers have identified student benefits from such strategies, yet these benefits may not be universal for all students. We sought to identify how students at a nontraditional university perceive introductory biology and chemistry courses, and whether perceptions relate to course type, performance, or student status. We surveyed students ( n = 601) using open-ended prompts regarding their perceptions of factors that impact their learning and interest, and about specific learning strategies. Generally, students did not differ in what influenced their learning or interest in course content, and students mostly perceived active learning positively. Attitudes toward active learning did not correlate to final course scores. Despite similar perceptions and attitudes, performance differed significantly among student groups-postbaccalaureates outperformed all others, and traditional-age students outperformed non-traditional-age students. We found that, even with active learning, underrepresented minority students underperformed compared to their peers, yet differentially benefited from nonsummative course factors. Although students generally perceive classroom environments similarly, undetected factors are influencing performance among student groups. Gaining a better understanding of how classroom efforts impact all of our students will be key to moving beyond supposing that active learning simply "works."


Subject(s)
Attitude , Biology/education , Chemistry/education , Curriculum , Perception , Students , Adolescent , Female , Focus Groups , Humans , Male , Problem-Based Learning , Universities , Young Adult
15.
CBE Life Sci Educ ; 17(3): ar43, 2018 09.
Article in English | MEDLINE | ID: mdl-30142051

ABSTRACT

Graduate students hold a critical role in responding to national calls for increased adoption of evidence-based teaching (EBT) in undergraduate classrooms, as they not only serve as teaching assistants, but also represent the pool from which future faculty will emerge. Through interviews with 32 biology graduate students from 25 institutions nationwide, we sought to understand the progress these graduate students are making in adopting EBT through qualitative exploration of their perceptions of and experiences with both EBT and instructional professional development. Initial inductive content analysis of interview transcripts guided the holistic placement of participants within stages of Rogers's diffusions of innovations model, which we use as a theoretical framework to describe the progress of EBT adoption. We found that most graduate students in our sample are aware of and value EBT, but only 37.5% have implemented EBT. Many who were progressing toward EBT adoption had sought out supplementary instructional experiences beyond the requirements of their programs, and 72% perceived an institutional lack of support for teaching-related professional development opportunities. These data indicate that, while many graduate students are already engaged with the movement to adopt EBT, graduate training programs should emphasize increasing access to quality training in EBT strategies.


Subject(s)
Biology/education , Students , Teaching , Adult , Female , Humans , Male , Perception
16.
Am J Bot ; 105(7): 1232-1238, 2018 07.
Article in English | MEDLINE | ID: mdl-30035817

ABSTRACT

PREMISE OF THE STUDY: Sex-ratio variation occurs widely in dioecious plants, but the mechanisms of population sex-ratio bias are poorly understood. In bryophytes, sex ratios are often female biased, and little information is available about how and when bias forms. METHODS: To test whether population sex-ratio variation can emerge during the gametophytic phase and is not purely a product of spore sex ratios, we created artificial populations of the moss Ceratodon purpureus, with male- and female-biased sex ratios, and placed half under a stress treatment. We hypothesized that male-majority populations would become female-biased and that stress would increase this transition. After 18 mo, when sporophytes were initially forming, we used sex-specific molecular markers to determine population sex ratios. KEY RESULTS: Female-majority populations did not differ significantly from their original bias, whereas male-majority populations became significantly more female biased. The plants had only just produced their first spores, so these sex-ratio changes occurred during the gametophytic generation, as a result of sex-specific growth or survival. Sporophytes occurred only in populations with female-biased final sex ratios, which suggests that females in male-majority populations may have invested energy in ramets rather than in sporophyte production. The stress treatment was mild and had no effect on sex ratio. CONCLUSIONS: Our results suggest that female bias can be generated during the gametophytic generation, before plants reach sexual maturity. These results, combined with those of previous work, suggest that both the gametophytic and the sporophytic stages drive population sex ratios in C. purpureus, thus indicating that multiple mechanisms operate to create biased population sex ratios.


Subject(s)
Bryopsida/physiology , Germ Cells, Plant/physiology , Reproduction , Sex Ratio
17.
PLoS One ; 13(6): e0199576, 2018.
Article in English | MEDLINE | ID: mdl-29940027

ABSTRACT

Many current faculty believe that teaching effort and research success are inversely correlated. This trade-off has rarely been empirically tested; yet, it still impedes efforts to increase the use of evidence-based teaching (EBT), and implement effective teaching training programs for graduate students, our future faculty. We tested this tradeoff for graduate students using a national sample of life science PhD students. We characterize how increased training in EBT impacts PhD students' confidence in their preparation for a research career, in communicating their research, and their publication number. PhD students who invested time into EBT did not suffer in confidence in research preparedness, scientific research communication, or in publication number. Instead, overall, the data trend towards a slight synergy between investing in EBT and research preparation. Thus, the tension between developing research and teaching skills may not be salient for today's graduate students. This work is proof of concept that institutions can incorporate training in EBT into graduate programs without reducing students' preparedness for a research career. Although some institutions already have graduate teaching programs, increasing these programs at scale, and including training in EBT methods could create a new avenue for accelerating the spread of evidence-based teaching and improved teaching across higher education.


Subject(s)
Education, Graduate , Research Personnel/education , Research , Students , Teaching , Adult , Biological Science Disciplines/education , Education, Graduate/methods , Female , Humans , Male , Periodicals as Topic , Proof of Concept Study , Research Personnel/psychology , Scholarly Communication , Self Report , Students/psychology
18.
J Microbiol Biol Educ ; 18(2)2017 Apr.
Article in English | MEDLINE | ID: mdl-28656071

ABSTRACT

Course-based undergraduate research experiences (CUREs) meet national recommendations for integrating research experiences into life science curricula. As such, CUREs have grown in popularity and many research studies have focused on student outcomes from CUREs. Institutional change literature highlights that understanding faculty is also key to new pedagogies succeeding. To begin to understand faculty perspectives on CUREs, we conducted semi-structured interviews with 61 faculty who teach CUREs regarding why they teach CUREs, what the outcomes are, and how they would discuss a CURE with a colleague. Using grounded theory, participant responses were coded and categorized as tangible or intangible, related to both student and faculty-centered themes. We found that intangible themes were prevalent, and that there were significant differences in the emphasis on tangible themes for faculty who have developed their own independent CUREs when compared with faculty who implement pre-developed, national CUREs. We focus our results on the similarities and differences among the perspectives of faculty who teach these two different CURE types and explore trends among all participants. The results of this work highlight the need for considering a multi-dimensional framework to understand, promote, and successfully implement CUREs.

19.
Ann Bot ; 119(1): 27-38, 2017 01.
Article in English | MEDLINE | ID: mdl-27794516

ABSTRACT

BACKGROUND AND AIMS: The Western Antarctic Peninsula is one of the most rapidly warming regions on Earth, and many biotic communities inhabiting this dynamic region are responding to these well-documented climatic shifts. Yet some of the most prevalent organisms of terrestrial Antarctica, the mosses, and their responses to warming have been relatively overlooked and understudied. In this research, the impacts of 6 years of passive warming were investigated using open top chambers (OTCs), on moss communities of Fildes Peninsula, King George Island, Antarctica. METHODS: The effects of experimental passive warming on the morphology, sexual reproductive effort and stress physiology of a common dioicous Antarctic moss, Polytrichastrum alpinum ,: were tested, gaining the first species-specific mechanistic insight into moss responses to warming in the Antarctic. Additionally community analyses were conducted examining the impact of warming on overall moss percentage cover and sporophyte production in intact Antarctic moss communities. KEY RESULTS: Our results show a generally greater percentage moss cover under warming conditions as well as increased gametangia production in P. alpinum Distinct morphological and physiological shifts in P. alpinum were found under passive warming compared with those without warming: warmed mosses reduced investment in cellular stress defences, but invested more towards primary productivity and gametangia development. CONCLUSIONS: Taken together, results from this study of mosses under passive warming imply that in ice-free moss-dominated regions, continued climate warming will probably have profound impacts on moss biology and colonization along the Western Antarctic Peninsula. Such findings highlight the fundamental role that mosses will play in influencing the terrestrialization of a warming Antarctica.


Subject(s)
Bryophyta/physiology , Antarctic Regions , Global Warming , Reproduction/physiology , Stress, Physiological/physiology
20.
Am J Bot ; 103(4): 625-34, 2016 04.
Article in English | MEDLINE | ID: mdl-27022007

ABSTRACT

PREMISE OF STUDY: Our ability to explain community structure rests on our ability to define the importance of ecological niches, including realized ecological niches, in shaping communities, but few studies of plant distributions have combined predictive models with physiological measures. METHODS: Using field surveys and statistical modeling, we predicted distribution drivers in geothermal bryophyte (moss) communities of Lassen Volcanic National Park (California, USA). In the laboratory, we used drying and rewetting experiments to test whether the strong species-specific effects of relative humidity on distributions predicted by the models were correlated with physiological characters. KEY RESULTS: We found that the three most common bryophytes in geothermal communities were significantly affected by three distinct distribution drivers: temperature, light, and relative humidity. Aulacomnium palustre, whose distribution is significantly affected by relative humidity according to our model, and which occurs in high-humidity sites, showed extreme signs of stress after drying and never recovered optimal values of PSII efficiency after rewetting. Campylopus introflexus, whose distribution is not affected by humidity according to our model, was able to maintain optimal values of PSII efficiency for 48 hr at 50% water loss and recovered optimal values of PSII efficiency after rewetting. CONCLUSIONS: Our results suggest that species-specific environmental stressors tightly constrain the ecological niches of geothermal bryophytes. Tests of tolerance to drying in two bryophyte species corresponded with model predictions of the comparative importance of relative humidity as distribution drivers for these species.


Subject(s)
Bryophyta/physiology , Geothermal Energy , Bryophyta/radiation effects , Circadian Rhythm/physiology , Desiccation , Fluorescence , Humidity , Light , Regression Analysis , Species Specificity , Temperature
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