Leaf detective: using evidence of damage on mangrove leaves to measure the effects of different herbivores

Abstract

Herbivores are important to ecosystems because they transfer energy stored in plant matter to other organisms. However, when herbivores occur in high abundances, they can become pests and harm the plants that form the basis of food webs. Mangroves are saltwater tolerant trees found along most tropical and subtropical shorelines. Because mangroves live between land and sea, a wide range of herbivores and other organisms, such as pathogens and parasites, affect them. Many of these organisms leave distinctive marks on the leaves that they eat or infect; scientists can use those marks to help identify the organisms that caused the damage. In this activity, students will take on the role of “Leaf Detectives” and examine patterns of leaf damage on red mangrove leaves (Rhizophora mangle) to infer which organism(s) are harming the mangroves on fictional Lobster Island. Students will collect data from their sample leaves, summarize the results with a graph, and then make a conclusion based on the scientific evidence. By classifying and measuring different damage patterns on leaves, students will learn how different organisms affect plants and food webs, develop pattern recognition skills, and practice using the scientific method to make evidence-based conclusions.     

??Are Humans Evolving??? A Classroom Discussion to Change Student Misconceptions Regarding Natural Selection

Natural selection is an important mechanism in the unifying biological theory of evolution, but many undergraduate students struggle to learn this concept. Students enter introductory biology courses with predictable misconceptions about natural selection, and traditional teaching methods, such as lecturing, are unlikely to dispel these misconceptions. Instead, students are more likely to learn natural selection when they are engaged in instructional activities specifically designed to change misconceptions. Three instructional strategies useful for changing student conceptions include (1) eliciting na?ve conceptions from students, (2) challenging nonscientific conceptions, and (3) emphasizing conceptual frameworks throughout instruction. In this paper, we describe a classroom discussion of the question “Are humans evolving?” that employs these three strategies for teaching students how natural selection operates. Our assessment of this activity shows that it successfully elicits students’ misconceptions and improves student understanding of natural selection. Seventy-eight percent of our students who began this exercise with misconceptions were able to partially or completely change their misconceptions by the end of this discussion. The course that this activity was part of also showed significant learning gains (d = 1.48) on the short form of the Conceptual Inventory of Natural Selection. This paper includes all the background information, data, and visual aids an instructor will need to implement this activity.     

Could Bacillus biofilms enhance the effectivity of biocontrol strategies in the phyllosphere?

Maize (Zea mays L.), a major crop in Argentina and a staple food around the world, is affected by the emergence and re-emergence of foliar diseases. Agrochemicals are the main control strategy nowadays; however, they can cause resistance in insects and microbial pathogens and have negative effects on the environment and human health. An emerging alternative is the use of living organisms, i.e. microbial biocontrol agents, to suppress plant pathogen populations. This is a risk-free approach when the organisms acting as biocontrol agents come from the same ecosystem as the foliar pathogens they are meant to antagonize. Some epiphytic microorganisms may form biofilm by becoming aggregated and attached to a surface, as is the case of spore-forming bacteria from the genus Bacillus. Their ability to sporulate and their tolerance to long storage periods make them a frequently used biocontrol agent. Moreover, the biofilm that they create protects them against different abiotic and biotic factors and helps them to acquire nutrients, which ensures their survival on the plants they protect. This review analyzes the interactions that the phyllosphere-inhabiting Bacillus genus establishes with its environment through biofilm, and how this lifestyle could serve to design effective biological control strategies.     

Reconstructing Earth's Past Climates: The Hidden Secrets of Pollen

Palynology is the study of fossil pollen and spores, and these tiny grains can provide fundamental information about past climates on Earth. Among their many unique and useful properties, pollen and spores are composed of some of the most chemically resistant organic compounds found in nature. They are also produced in vast quantities and are unique to the specific plant from which they originate. All these features make them ideal to reconstruct past climates from both recent history as well as from the ancient past. The purpose of this activity is to get students familiar with palynology and how scientists study climate change. It is based on real palynological data acquired from Antarctic cores obtained recently from the ANDRILL and SHALDRIL drilling campaigns. In order for students to understand this research and its importance, they will separate and identify pollen and spores from a simulated core sample in which different species of plants are represented as different colors of glitter. Students will compare the types and abundance of pollen and spores found in each layer of the core sample and research the climate preferences of the types of plants recovered in order to reconstruct the past climates of Antarctica.     

Using concept maps to characterise cellular respiration knowledge in undergraduate students

ABSTRACT

Meaningful learning occurs by relating new information to and revising prior knowledge, making it essential to understand student knowledge before helping them move toward a more scientific understanding. In this study, we characterise prior knowledge about cellular respiration in undergraduate students enrolled in introductory biology by analysing student-constructed concept maps (N = 182) and interviews (N = 9). Students were instructed to create concept maps from a bank of 20 concepts with the purpose of interconnecting the processes of cellular respiration, showing how pools of ATP are generated and used, and identifying where the events of cellular respiration occur. Student maps were analysed for content, quality and organisation of knowledge. Interviews were used to corroborate inferences made from concept maps. Students had a simplified understanding of cellular respiration and its processes as evident by cognitive structures with limited quantities of schemas that were vaguely connected and linearly organised. Furthermore, students had a better understanding of glycolysis than fermentation. Instructors can use these findings to help students build better knowledge of cellular respiration by focusing on incorporating relevant schemas, creating quality connections among schemas, and organising their knowledge of cellular respiration to reflect biological complexity.     

Attitudes of Students at a Private Christian Liberal Arts University Toward the Teaching of Evolution

Students at private Christian colleges tend to have a viewpoint that incorporates faith and belief in God. Whether due to misconceptions about evolution, lack of knowledge of the nature of science, or belief that their faith cannot allow them to accept evolution, there tends to be a great deal of confusion about evolution. This study investigates the attitudes toward evolution of students at a small Christian liberal arts university located in east Texas (East Texas Baptist University, ETBU) and how they would feel most comfortable being approached about evolution in the college science classroom. The majority of students at ETBU are from either Texas or Louisiana. In high school, both states require at least one science course to be taken and evolution to be taught at some level of understanding. Students show a fair understanding that science includes only naturalistic explanations . However, a greater number of science courses and maturity level of the student resulted in significant differences (P = 0.0001 and P = 0.002, respectively) in the understanding of science. Nevertheless, there was a general assertion that God should be included in the definition of science by the majority of students (64.4%), indicating a misunderstanding of the nature of science. Students responded that they would be most comfortable with being approached in the classroom about evolution through the presentation of the science supporting evolution (19.6%), and being shown how creationism and intelligent design are not science (29.8%). A number of students responded that the professor should accept creationism and intelligent design as science and teach them as such (38.2%). This paper will present methods to address students that respond to evolution in this manner.     

A strategy for evaluating the safety of organisms for biological weed control

A strategy for establishing the specificity and safety of an organism as a biological weed control agent is described. A critical first step is to expose to its attack a small group of plants very closely related and exhibiting morphological and biochemical similarities to the weed. To prevent an erroneous negative result tests are also made on selected cultivated plants, including those closely related to the weed, those of which the associated insects and fungi are little known, those that have evolved apart from or been little exposed to the agent, those attacked by closely related organisms and those already recorded as hosts. The circumstances under which the strategy might fail to indicate safety are discussed, i.e. polyphagous organisms attacking plants irregularly distributed throughout many families, organisms highly specific to two alternate hosts, and those attacking two or three phylogenetically widely separated plant groups. The additional crop plant testing, included in the overall strategy to deal with such possible failures, is discussed. It is shown that the strategy would have included Sesamum tndicum in the list of plants challenged by the bug Teleonemia scrupulosa in biological testing for control of Lantana camara, thereby forewarning of the attack that was subsequently observed in Africa.     

Investigating high school students' conceptualizations of the biological basis of learning

Students go to school to learn. How much, however, do students understand about the biological basis of this everyday process? Blackwell et al. (1) demonstrated a correlation between education about learning and academic achievement. Yet there are few studies investigating high school students' conceptions of learning. In this mixed-methods research study, written assessments were administered to 339 high school students in an urban school district after they completed their required biology education, and videotaped interviews were conducted with 15 students. The results indicated that the majority of students know little about the biological basis of learning, even with prompting, and they recall having learned little about it in school. Students appear to believe that people control their own ability to learn, and some have developed personal hypotheses to describe the learning process. On written assessments, 75% of participants demonstrated a nonbiological framework for learning, and, during interviews, 67% of participants revealed misconceptions about the biological basis of learning. Sample quotes of these interviews are included in this report, and the implications of these findings are discussed.     

Comparing Conservation Priorities for Useful Plants Among Botanists and Tibetan Doctors

Perspectives of diverse constituencies need to be incorporated when developing conservation strategies. In Menri (Medicine Mountains) of the Eastern Himalayas, Tibetan doctors and professional botanists were interviewed about conservation of useful plants. We compare these two perspectives and find they differ significantly in conservation priorities (Wilcoxon Signed Ranks P < 0.05), both in how they prioritized, as well as the priorities themselves. Tibetan doctors first consider which plants are most important to their medical practice and, then secondarily, the conservation status of these plants. Additionally, perceptions of threatened medicinal plants differ among Tibetan doctors who received medical training in Lhasa, who were local trained, and who were self-taught. In contrast, professional botanists came to a consensus among themselves by first considering the conservation status of plants and then considering use. We conclude that, in order to effect community based conservation, opinions from both Tibetan doctors and professional botanists should be considered in establishing conservation priorities and sustainable conservation programs. Furthermore, we set our own research agenda based on combined perspectives.     

Effects of cotton cultivars differing in gossypol content on the quality of Aphis gossypii as prey for two species of Coccinellidae

Plants can have detrimental effects on biological control agents by affecting their prey or host quality. Thus, it is important to understand the tri-trophic interactions between plants, herbivores and natural enemies when implementing biological control programmes. Studies have shown that both morphological and chemical traits of host plants can affect the third trophic level. Cotton plants are known to produce alkaloids such as gossypol, a sesquiterpene aldehyde that can confer resistance against herbivorous arthropods. Nevertheless, little is known about the effect of gossypol on biological control agents. In this study, we investigated how three cotton cultivars (BRS Rubi, BRS Safira and BRS Verde) differing in gossypol content affect development and growth of predatory coccinellids, Eriopis connexa and Harmonia axyridis, feeding on the cotton aphid Aphis gossypii reared on those cultivars. The results show that the cultivar BRS Rubi (highest gossypol content) had a sub-lethal effect on the development and growth of both Coccinellidae species compared with the other cultivars. Overall, the cultivar BRS Rubi reduced slightly fecundity, net reproductive rate and intrinsic rate of natural increase for both Coccinellidae species. However, because aphid populations stay short periods of time in the field, and adult coccinellids may supplement its diet with alternative prey and plant material this sub-lethal indirect effect of gossypol may not have a detrimental effect on field biological control of cotton aphid by either E. connexa or H. axyridis, thus suggesting a compatibility between plant resistance and biological control agents.     

Voluntary participation in an active learning exercise leads to a better understanding of physiology

Students learn best when they are focused and thinking about the subject at hand. To teach physiology, we must offer opportunities for students to actively participate in class. This approach aids in focusing their attention on the topic and thus generating genuine interest in the mechanisms involved. This study was conducted to determine if offering voluntary active learning exercises would improve student understanding and application of the material covered. To compare performance, an anonymous cardiorespiratory evaluation was distributed to two groups of students during the fall (control, n = 168) and spring (treatment, n = 176) semesters. Students in both groups were taught by traditional methods, and students in the treatment group had the option to voluntary participate in two additional active learning exercises: 1) a small group discussion, where students would discuss a physiology topic with their Teaching Assistant before running BIOPAC software for the laboratory exercise and 2) a free response question, where students anonymously responded to one short essay question after the laboratory exercise. In these formative assessments, students received feedback about their present state of learning from the discussion with their peers and also from the instructor comments regarding perceived misconceptions. As a result of the participation in these activities, students in the treatment group had a better overall performance [χ(2) (degree of freedom = 1) = 31.2, P < 0.001] on the evaluation (treatment group: 62% of responses correct and control group: 49%) with an observed difference of 13% (95% confidence interval: 8, 17). In conclusion, this study presents sufficient evidence that when the opportunity presents itself, students become active participants in the learning process, which translates into an improvement in their understanding and application of physiological concepts.     

Considering the levels of biological organisation when teaching carbon flows in a terrestrial ecosystem

ABSTRACT

Students often have misconceptions about terrestrial carbon flows and there is a lack of coherence in students’ explanations regarding the different levels of biological organisation at which these processes occur. In this study, problem-based teaching materials on the topic of terrestrial carbon flows were developed and tested with 15 students 18–19 years old (grade 12) using a pre/post-test design. Students focused on specific carbon flows in an ecosystem at the macro level (e.g. CO₂ fixation and heterotrophic respiration) including specific related concepts at the micro level (e.g. photosynthesis and cellular respiration). The findings indicate that the teaching materials improved the students’ understanding of terrestrial carbon flows and their ability to reason across the different levels of biological organisation. On the basis of these findings, implications for teaching terrestrial carbon flows in biological education are discussed.     

Cognitive Change in Obese Adolescents Losing Weight

Objectives: To investigate how obese adolescents think about themselves in terms of exercise, eating, and appearance and whether these cognitions change over the course of a residential weight loss camp. Research Methods and Procedures: Obese adolescents [N = 61; age, 14.1 (±0.2) years; BMI, 33.9 (±0.7) kg/m²] completed assessments of body weight and height and self‐esteem and a sentence‐completion test eliciting thoughts and beliefs about exercise, eating, and appearance at the start and end of the camp (mean stay, 26 days). They were compared with a single assessment of 20 normal‐weight adolescents [age, 15.4 (±0.2) years; BMI, 21.8 (±0.5) kg/m²]. Results: The obese adolescents lost 5.7 kg and reduced their BMI SD score by 0.25. Camp residence was associated with a significant reduction in the number of negative automatic thoughts and an increase in positive thoughts, especially related to exercise and appearance. There was no change in conditional beliefs, either functional or dysfunctional. Including BMI SD score change as a covariate took away all the main and interaction effects of time, showing that cognitive change was largely accounted for by the reduction in weight. Despite this improvement, campers remained cognitively more negative and dysfunctional than the normal‐weight comparison adolescents. Discussion: Obese adolescents not only lost weight, but they improved their self‐representation, specifically in terms of automatic thoughts about exercise and appearance. Although these are short‐term cognitive changes, they reflect positively on the camp experience and show the value of psychological improvement in assessing obesity‐treatment outcomes.     

Individually mark–mass release–resight study elucidates effects of patch characteristics and distance on host patch location by an insect herbivore

1. How organisms locate their hosts is of fundamental importance in a variety of basic and applied ecological fields, including population dynamics, invasive species management and biological control. However, tracking movement of small organisms, such as insects, poses significant logistical challenges. 2. Mass‐release and individual–mark–recapture techniques were combined in an individually mark–mass release–resight (IMMRR) approach to track the movement of over 2000 adult insects in an economically important plant–herbivore system. Despite its widespread use for the biological control of the invasive thistle Carduus nutans, the host‐finding behaviour of the thistle head weevil Rhinocyllus conicus has not previously been studied. Insects were released at different distances from a mosaic of artificially created host patches with different areas and number of plants to assess the ecological determinants of patch finding. 3. The study was able to characterize the within‐season dispersal abilities and between‐patch movement patterns of R. conicus. Weevils found host plant patches over 900 m away. Large patches, with tall plants, situated close to the nearest release point had the highest first R. conicus resights. Patch area and plant density had no effect on the number of weevils resighted per plant; however, R. conicus individuals were more likely to disperse out of small patches and into large patches. 4. By understanding how R. conicus locates host patches of C. nutans, management activities for the control of this invasive thistle can be better informed. A deeper mechanistic understanding of host location will also improve prediction of coupled plant–herbivore spatial dynamics in general.     

Holobionts and the ecology of organisms: Multi-species communities or integrated individuals?

It is now widely accepted that microorganisms play many important roles in the lives of plants and animals. Every macroorganism has been shaped in some way by microorganisms. The recognition of the ubiquity and importance of microorganisms has led some to argue for a revolution in how we understand biological individuality and the primary units of natural selection. The term “holobiont” was introduced as a name for the biological unit made up by a host and all of its associated microorganisms, and much of this new debate about biological individuality has focused on whether holobionts are integrated individuals or communities. In this paper, I show how parts of the holobiont can span both characterizations. I argue that most holobionts share more affinities with communities than they do with organisms, and that, except for maybe in rare cases, holobionts do not meet the criteria for being organisms, evolutionary individuals, or units of selection.     

Biology-specific vocabulary: students’ understanding and lecturers’ expectations of student understanding

Abstract

The current A-level biology curriculum includes a broad coverage of all the biosciences which demands knowledge of a wide range of biological vocabulary. Students (n = 184) from two UK universities were presented with a list of vocabulary, associated with a ‘Revise Biology’ text which highlighted key terms that students should know. Lecturers (n = 26) were asked which of these terms they expected students to know, or be aware of. Findings revealed that students’ claimed knowledge of vocabulary exceeded lecturer expectations. In addition, there were a number of terms which students did not understand and lecturers did not expect them to know, which could be removed from A-level biology courses. This is discussed in relation to whether A-level curricula need to be so content heavy and whether lecturers would benefit from knowing more about their students’ knowledge of discipline-specific terms.     

Integration of laboratory exercises in developmental biology and neurobiology courses using the Xenopus oocyte expression system

This collaborative laboratory exercise integrates two upper division laboratory courses (Developmental Biology and Neurobiology) offered to biology majors at Wake Forest University. The laboratory exercise involves the use of the Xenopus oocyte expression system to study the function of specific membrane receptors and ligand-activated channels. cDNA or mRNA for receptor proteins is injected into Xenopus oocytes. The oocytes are assayed for expression of receptor proteins and two-electrode voltage clamping is done to determine whether the expressed proteins are functional in the oocyte system. This series of laboratory exercises is innovative in its interdisciplinary and collaborative approach to undergraduate teaching, and in its use of sophisticated molecular biological and physiological techniques in the undergraduate teaching laboratory. Students learn first-hand how these techniques have been used to achieve a new level of understanding of both development and neurobiology. Journal of Industrial Microbiology & Biotechnology (2000) 24, 353–358. Received 02 April 1999/ Accepted in revised form 10 November 1999     

We're Gonna Crush It! Sediment Creation through Destruction

Why are there only crumbs left at the bottom of the cereal box? Many factors, such as package handling, have caused the cereal pieces to break down into crumbs. This explanation is also related to the process of creating sediment from rocks. Sediment is created by weathering over millions of years, and it is deposited all over the world by erosion. The We're Gonna Crush It! activity serves as a brief introduction to sediment composition. Students learn how sediment is created by demonstrating weathering at a much quicker pace than what occurs under natural conditions. They see firsthand how weathering affects rocks by mirroring the process using cereal to make “sediment.” The students learn how to calculate grain size percentages to determine the overall composition of the sediment while becoming more aware of the organisms and organic matter that are also present. In less than 60 min, students can experience a large-scale process that generally occurs over millions of years. Several Next Generation Science Standards, Common Core Math Standards, and Ocean Literacy Standards are addressed in this activity.     

EOV Editorial Board

Why are there only crumbs left at the bottom of the cereal box? Many factors, such as package handling, have caused the cereal pieces to break down into crumbs. This explanation is also related to the process of creating sediment from rocks. Sediment is created by weathering over millions of years, and it is deposited all over the world by erosion. The We're Gonna Crush It! activity serves as a brief introduction to sediment composition. Students learn how sediment is created by demonstrating weathering at a much quicker pace than what occurs under natural conditions. They see firsthand how weathering affects rocks by mirroring the process using cereal to make “sediment.” The students learn how to calculate grain size percentages to determine the overall composition of the sediment while becoming more aware of the organisms and organic matter that are also present. In less than 60 min, students can experience a large-scale process that generally occurs over millions of years. Several Next Generation Science Standards, Common Core Math Standards, and Ocean Literacy Standards are addressed in this activity.