Faculty of Biological Sciences, University of Leeds
University of Tartu. Tartu , Estonia. Keywords: anti-aging, Ayurveda, pomegranate, Rasayana, competition, Troponin, Flight muscles, Protein stoichiometry, muscle hypercontraction, Alternative promoters, NTM, Autonomous University of Barcelona.
Keywords: biolinguistics, Evo-Devo, theory of development, Boundaries of development, cognitive phenotypes, language evolution, Computation, homology, novelty. Universidad de Oviedo Mieres. Mieres , Spain. Keywords: cognitive development, cognitive evolution, Homologies, Novelties, identity theory, Multiple realizability, Ahistorical homology, Boundaries of development, Paris , France. Keywords: Regeneration, development, robustness, Evo-Devo, Evolvability, phylogenesis, Developmental constraints, developmental modularity.
Evolutionary developmental biology - Latest research and news | Nature
Armin P. If you block a person from following you: This person will not be able to follow your research activity. At the same time we encounter another common problem: all insects in the strict sense have wings except those that secondarily lost them. Thus, no comparisons are possible between ancestrally wingless and slighty winged and partially winged and almost fully winged insects. Instead that variation has been lost in deep time and is unavailable for present day studies.
Lacking both obvious correspondence to other traits and phenotypic variation within populations or among closely related species, conventional evolutionary biology has difficulty framing an adequate research program through which to address the issue of novelty. As a consequence, we have learned a great deal about the quantitative and population genetic architecture of insect wing size and shape, but very little about the very origin of the first wing.
It took the discipline of evo devo to provide a more productive way of thinking and framing a research program on evolutionary novelty to make headway. While traditional approaches focus on how variation is transmitted across generations, and how this process might explain long-term evolutionary transitions, they run into trouble when suitable variation is not experimentally accessible, as in the case of insect wings.
In contrast, evo devo expands the focus to include how traits are made during development, and how the process of building a trait trait construction compares to that of other traits, regardless of whether they do or do not share obvious homology. This seemingly simple extension makes a difference for many reasons, three of which in particular are worth highlighting here.
Swallowtail butterflies have diversified greatly in wing tail size and shape. Understanding the biological basis of form Evo devo provides a much deeper understanding of the biological basis of organismal form and function by filling an abstract genotype-phenotype map with the realities of developmental pathways, cells, signaling molecules, morphogenetic movements, and the processes of tissue differentiation. This can profoundly impact the research approach used to study the evolution of a given trait. For example, the tails of swallowtail butterflies see images are perhaps not exactly a novelty, but certainly an interesting trait which has diversified significantly within this group.
And some species, as well as genotypes within populations, seem to possess heritable variation that enhances or mutes the further extension of these outgrowths. But once researchers examined how wing tails form during development all this had to be revised.
It turns out that the wings of swallowtails at the pupal stage, which at this point have completed all of their growth, lack tails. Based on results of surveys and interviews with students, we suggest that teaching core concepts CCs within a framework that integrates supporting concepts SCs from both evolutionary and developmental biology can improve evo-devo instruction.
We articulate CCs, SCs, and foundational concepts FCs that provide an integrative framework to help students master evo-devo concepts and to help educators address specific conceptual difficulties their students have with evo-devo. We then identify the difficulties that undergraduates have with these concepts.
Most of these difficulties are of two types: those that are ubiquitous among students in all areas of biology and those that stem from an inadequate understanding of FCs from developmental, cell, and molecular biology. Developmental aspects of evolution evo-devo form an essential part of our understanding of evolution. Other concepts substantially expand our understanding of evolutionary processes, such as the concept that development can bias evolutionary outcomes and the concept that phenotypic novelty can arise via the redeployment of an existing developmental process to a novel developmental context.
Recognition of the importance of evo-devo, as well as the pedagogical gains that can be made by taking an evo-devo approach in the classroom Gilbert, ; Love, , has fueled recent attempts to incorporate evo-devo into evolutionary biology curricula, typically as discrete, supplementary modules Platt, ; but see Arthur, Evo-devo concepts, especially the conservation of HOX genes and regulatory networks across phyla, now appear in the evolution sections of high school textbooks e. Evo-devo content presents students with new conceptual challenges and potential difficulties in attempting to understand evolution.
For example, while several evo-devo concepts rely on the supporting concept SC of conserved gene networks that operate in a variety of developmental contexts, many students hold that each trait of an observed phenotype is the result of the expression of a single gene Lewis and Kattmann, Improving strategies for teaching evo-devo will benefit from an inventory of concepts appropriate for undergraduates, a learning progression toward their mastery, and a description of their attendant conceptual difficulties. How information is presented to a student can affect how a student reasons and assembles links between concepts Gelman, ; Novak, Misconceptions arise when students inaccurately link concepts; misunderstandings arise when there are missing connections between related concepts Ausubel, ; Novak, Here we use the more inclusive term conceptual difficulty to describe any conception that differs from a conception commonly held by the scientific community Hammer, a , b , including misconceptions, misunderstandings, and alternative conceptions Wandersee and Reuter, To our knowledge, there are no published inventories of the concepts necessary for undergraduate students to have a working knowledge of evo-devo, nor are there any published reports on the conceptual difficulties that students of evo-devo are likely to encounter.
Our study was motivated by two questions: 1 What concepts do undergraduate students need to have a working knowledge of evo-devo? In this paper, we articulate core concepts CCs , SCs, and foundational concepts FCs associated with evo-devo that undergraduate biology majors ought to master. We then report on conceptual difficulties that currently prevail among undergraduate students attempting to learn evo-devo. Not only will this inventory of concepts and associated conceptual difficulties help us meet the long-term goal of developing an instrument to quantify student understanding of evo-devo e.
We supplemented this initial list by reviewing the evo-devo and educational literature, drawing heavily from Hiatt et al. Next, we administered a survey that asked experts to evaluate this initial list of evo-devo concepts. We defined an expert as someone who actively contributes, teaches, or conducts research in an area related to evo-devo. Experts reviewed each of the concepts by evaluating its importance for biology majors and indicating whether they teach the concept in their courses. Experts also had the opportunity to provide additional comments on each concept and describe concepts not included in the list.
We used these data to revise the initial list of concepts and then compile a final, master list. The conceptual difficulties that undergraduate biology majors have were compiled from several rounds of surveys and interviews. These were conducted at a variety of institutions to include a wide range of student backgrounds and regional diversity within the United States. All surveys and interviews were performed with informed consent and were deemed exempt by institutional review boards RIU IRB nos.
Very few students in this survey had taken a course in developmental biology, although some upper-level students had taken a course in cell biology. None of the MCU students in our sample had taken such courses. In general, at all the institutions sampled, students were much more likely to be exposed to evolutionary, as opposed to developmental, biology content. Two exploratory open-response surveys were developed Supplemental Material, surveys 1 and 2 to elicit responses from primarily lower-level students to sets of questions addressing our list of CCs, SCs, and FCs.
Each survey consisted of a description of a scenario followed by several questions. Although there was some overlap in survey items, having two distinct shorter surveys allowed us to assess a large number of students while not burdening any one student with an overly long survey. Survey 1 was administered to: students from lower-level courses on animal biology, plant biology, and introductory biology and upper-level courses on evolution, stream invertebrates, anatomy and physiology, environmental toxicology, and science education research methods MCU ; and four high school seniors enrolled in a primate biology course PHS.
Survey 2 was administered to 42 students in a senior-level evolution course RIU. Although surveys 1 and 2 were largely administered to lower-level students, some upper-level students were included in the sample. This is in contrast to responses that were incorrect, because they contained one or more identifiable conceptual difficulties.
This large number of uncodable responses is expected when questions are difficult to interpret or the respondent has little working knowledge needed to answer a question Tamir, Given that many of these students have not been exposed to evo-devo concepts, it is not surprising many were unable to answer these questions sufficiently.
In response to the large number of uncodable responses from the first two surveys, we revised questions for survey 3 to reduce jargon and avoid eliciting common uncodable responses Duncan, Based on feedback from experts, questions were also revised to more precisely target concepts. Survey 3 was administered at the following institutions: MCU: 61 students in an upper-level evolution and genetics course; RIU: 39 students in upper-level evolution and vertebrate morphology courses; PU: 11 students from upper-level courses in genetics and evolution and the first course in an introductory biology sequence.
Data from all three exploratory surveys were analyzed for discernible patterns in student responses Berelson, We determined whether students consistently gave similar answers for each question and also identified conceptual difficulties that consistently prevented students from answering a question correctly. Finally, we identified instances in which we were unsure of the source of error in a student's response and pursued these with student interviews.
Surveys 1 and 2 were mostly administered to lower-level students and did not contain questions addressing all the CCs that appear in survey 3, which was administered primarily to upper-level students. Therefore, to calculate the frequency of conceptual difficulties, we only used student responses from survey 3. To confirm the understandings or conceptual difficulties we inferred based on written responses, we constructed survey 4 interview only to address more closely some of the concepts with which students struggled Supplemental Material, survey 4. Think-aloud interviews were conducted Patton, to give students the opportunity to define and explain their terminology while providing information about how they formulated explanations.
To prevent participant fatigue, we broke the questions down into subsets so that interviews would last no more than 30 min. Survey 4 was administered to upper-level students at RIU who identified as biology majors and included one zoology graduate student. Research assistants transcribed the audio recordings from those interviews. The process of categorizing conceptual difficulties was necessarily iterative to ensure agreement among investigators. To begin, two of us A. After agreement was reached, one investigator A.
We used the literature and data from the survey of experts to identify evo-devo concepts that could frame future evo-devo teaching.
What evolutionary developmental biology (evo devo) brings to evolutionary biology
We then examined open responses to survey questions and conducted interviews to identify conceptual difficulties that students experienced when trying to learn these concepts. Some of the frequently encountered conceptual difficulties were common to several subdisciplines of biology, whereas others stemmed from an inadequate understanding of development. Despite the variety of topics that fall under the umbrella of evo-devo, we found a broad consensus among experts on which evo-devo concepts undergraduate biology majors ought to know: Each CC relies on one or more SCs, which are divided into subcategories that rely on one or more FCs from developmental, cell, and molecular biology on the one hand, or the modern synthesis on the other Figure 1.
All told, we identified six core, 19 supporting, and six foundational evo-devo concepts. Figure 1. Student Excerpts 1 Question: You found a chicken egg, you hatched it out and observed that the chicken has a beak. Can you describe how the chicken's beak was formed? See Supplemental Material for the complete series. Example of a student response exhibiting developmental understanding: Student: The chicken beak was formed through a large amount of cell differentiation in development.
- Navigation Bar!
- Evolutionary Developmental Biology (Evo-Devo): Past, Present, and Future | SpringerLink;
- Evolutionary Developmental Biology - Department of Biology.
- Isle of Wight Villains: Rogues, Rascals and Reprobates;
- Navigation Bar.
- Laughing Into the Fourth Dimension.
Genes expressed by the chicken caused cells to differentiate into a beak. Examples of student responses that were considered uncodable follow. This category included responses that were deemed insufficient because the response was vague and did not provide enough information to identify any specific conceptual difficulty.
Student 1: It was developed in the embryo. Although most of the concepts we identified were deemed essential for understanding evo-devo, the list of concepts is not exhaustive. To explore student conceptual difficulties, we found it necessary to limit the number of concepts examined. Therefore, we elected not to examine FCs from evolutionary biology that have been articulated elsewhere e.
We also elected not to include concepts that were not consistently agreed upon in the expert survey as being essential for undergraduates attempting to gain a basic understanding of evo-devo, even though some are arguably of great importance evolutionarily. These included canalization Waddington, ; genetic assimilation and accommodation Schmalhausen, ; Waddington, ; West-Eberhard, ; although see CC6 ; epigenetic modification of DNA; gene duplication and genome evolution Lynch, ; serial homology; modularity Schlosser and Wagner, ; facilitated evolution Gerhart and Kirschner, ; and the evolution of multicellularity Grosberg and Strathmann, Collectively, they are integrative concepts in evo-devo and range from simpler concepts, such as the mere inclusion of development into the process of natural selection on variation CC6 , to more complex concepts, such as the notion that changes in the regulation of developmental processes can be a source of evolutionary novelty CC2 , that such changes can sometimes result from a small number of mutations CC1 , or that development can bias the direction of evolutionary change CC4.
Table 1. CCs in evo-devo that biology majors should understand and all the conceptual difficulties CD found in student responses associated with each CD data from survey 3. Table 3 defines the codes used to identify individual conceptual difficulties. These CCs rely on SCs from subcategories that are divided further in Table 2 : developmental mechanisms of evolutionary change SCa ; developmental bias, constraint, and conservation SCb ; developmental plasticity SCc ; and development in populations SCd.
These SCs in turn rely on FCs in development and evolution. Table 2. SCs and FCs essential for understanding the core evo-devo concepts, along with associated conceptual difficulties derived from survey 3. The dependence relationships between the foundational and SCs in this table and the core evo-devo concepts are illustrated in Figure 1.
Blank cells indicate that no conceptual difficulties were encountered in this study associated with the concept. The timing, location, and level of transcription are the result of upstream regulators, cis -regulatory regions enhancers , and perhaps alternate epigenetic modification of DNA. The timing, location, level, and nature of a protein product are the results of a variety of possible posttranscriptional regulatory mechanisms that include alternative RNA splicing, RNA editing, RNA transport, RNA stability, regulation of translation, and possibly other mechanisms that have not yet been described Stern, Several examples of student conceptual difficulties, as illustrated by excerpts of student responses from open-response surveys and interviews, are shown below.
Table 3 summarizes the conceptual difficulties we identified. Figure 2 shows the percentage of correct responses, uncodable responses, and responses containing conceptual difficulties for questions targeting each of the CCs and subcategories of SCs and FCs. Uncodable responses included those responses that were incorrect because they were incomplete, vague, or tautological, with the result that they did not provide enough context to determine any conceptual difficulty that a student might have see Student Excerpts 1 for examples.
Figure 2. Frequency of different types of student responses possessing conceptual difficulty, uncodable, and correct to questions targeting each of the CCs, the four categories of SCs, and FCs in developmental biology. Total number of responses was Table 3. Conceptual difficulties identified in survey 3 among biology majors and the number of times each difficulty was encountered a. Student Excerpts 2 Question: Insects such as the fruit fly Drosophila possess three pairs of legs, while other arthropods e. In all arthropods, including insects, Dll is a regulatory gene that is required for leg formation.
Provide an explanation for why Drosophila has fewer legs than Artemia. Student response exhibiting evo-devo thinking: Student: Dll is not as active in Drosophila , but is upregulated or more active in species like Artemia. Student response exhibiting teleological thinking CB1 : Student: No need for that many legs. Student response that is correct but incomplete because it lacks developmental thinking DV1 : Student 1: Flies have fewer legs because as years have passed, their bodies have changed in order to better fit its needs and that many legs wasn't necessary in order for the flies to survive.
Student 2: The environment, including habitat and food, of Drosophilia [ sic ] provides better chance of the individuals with fewer legs to survive. Thus, throughout the process of natural selection, among the various types of population due to genetic mutations, the ones with three pairs of legs survived more than the ones with more legs, and eventually weeding out the latter.
To understand the types of difficulties students expressed, we examined the prevalence, in upper-level students, of the four categories of conceptual difficulty among targeted concepts Figure 3. Smaller proportions of student responses indicated anthropomorphism CB3; 0. Figure 3. Prevalence of types of conceptual difficulties i. Note that a student response may include more than one conceptual difficulty and that the figure does not include uncodable responses.
Total number of codable responses was In addition to these common biological conceptual difficulties, many conceptual difficulties interfere specifically with the integration of development and evolution. For example, a student reasoning with minimal or incorrect information about the developmental mechanisms of evolutionary change SCa will have difficulty understanding how evolution can occur by changes in regulation CC2.
In this respect, conceptual difficulties that stem from poor or limited knowledge of development DV were the most prevalent overall; of student responses from survey 3, indicated a conceptual difficulty associated with developmental, cellular, or molecular biology Table 3. Of these, did not include any developmental reasoning, even when such reasoning was appropriate or the questions specifically prompted such reasoning DV1, see Student Excerpts 2 and Student Excerpts 3 for examples.
Instead, many of these responses 99 relied solely on natural selection as an explanatory mechanism. Even when informed during the interview that selection is an inadequate explanation, students in interviews still rely solely upon natural selection in their explanations see Student Excerpts 3. Student Excerpts 3 Question: All centipedes have an odd number of leg-bearing segments.
Centipedes vary in the number of leg-bearing segments, from as few as 5 to as many as , but none possess an even number. How might you explain this fact? A student response that exhibits a lack of developmental thinking DV1 with exclusive reliance on natural selection and the misuse of a term from genetics CB2 follows. Student: I would say they all might be odd because in some way it would be advantageous to their environment for how it came about and then it stayed that way because it never became disadvantageous … The genes for an even number of segments might just be so recessive that it's basically impossible to get them.
We observed a similar pattern when we examined the prevailing conceptual difficulties among responses to questions targeting the CCs and subcategories of SCs. DV conceptual difficulties were the most prevalent for most question types, other than those targeting CC2 and CC5 Figure 3. Another notable challenge for students was vocabulary. In survey 3, students misused terms in 8. This conflation hampers the ability to understand how changes in phenotype can result from changes in the regulation, and potentially expression, of a gene CC2.
The recent integration of evolution and development began with the advent of the synthetic field of evo-devo in the s Arthur, This wave of integration, however, has yet to permeate undergraduate life sciences curricula, in which traditional course structures unintentionally foster the tendency of students to compartmentalize knowledge rather than connecting it across traditional disciplines. We propose that the conceptual hierarchy presented in Figure 1 is also a pedagogical hierarchy that reflects the need for students to integrate in order to achieve a working knowledge of evo-devo.
These include difficulties that are common across biological disciplines, as well as those that are specific to the integration of evolution and development. We discuss below the implications of these findings for effectively teaching evo-devo. Evo-devo is popularly used Carroll, to demystify the origins of novelty Gilbert, and explain the underlying developmental mechanisms of evolution; however, students must have the supporting and foundational conceptual framework in order to articulate evo-devo concepts correctly.
For example, CC2—changes in the regulation of developmental processes can be a source of evolutionary novelty—relies on several SCs from the subcategory developmental mechanisms of evolutionary change SCa , including the concept that a change in the role a gene plays in development can lead to a change in phenotype SCa1 , which in turn relies on several FCs from development FCa , including the concept that a gene's role in development can be altered by, among other things, a change in the regulation of the gene FCa4.
Our results suggest that many students fail to integrate concepts from development, genetics, and evolution, and as a result, retain gaps or incorrect links in their conceptual understanding of evo-devo.
Evolutionary Developmental Biology
This lack of integration is ubiquitous among science and humanities disciplines and is a common challenge for college educators National Research Council, To assist instructors in helping students make these links, we suggest that the hierarchical framework of evo-devo concepts in Figure 1 be used as a pedagogical framework. For example, before teaching the concept that less-pleiotropic mutations are more likely to contribute to evolution CC3 , one must ensure that students possess the SCs and FCs that undergird this CC—for example, deleterious pleiotropic effects SCb4 and SCb5 and the ability of genes to play multiple roles during development FCa5.
Students who do not have a foundational understanding of the complex and interdependent roles that genes play in development may struggle to understand how development can influence the evolutionary process. Our study confirms that these misconceptions also interfere with the ability of students to understand concepts in evo-devo Table 3 and Figure 3. In particular, invoking purpose or need as a mechanism CB1, teleology was a common conceptual difficulty among our student responses, with Although these notions are not specific to evo-devo, instructors in this area should be aware of how such notions shape the way students understand the world.