The importance of cross-validation, accuracy, and precision for measuring plumage color: A comment on Vaquero-Alba et al. (2016)

Vaquero-Alba and colleagues published a study in The Auk: Ornithological Advances comparing objective color measurements of plumage taken in the field directly on a bird’s body to those taken in the lab on collected feathers arranged to emulate the appearance of a bird’s natural plumage. Although the field measures of plumage color were less repeatable than lab measures, the authors concluded that measurements taken in the field were more representative of a bird’s ‘‘true color.’’ Accordingly, they recommend that researchers should bring spectrophotometers into the field to measure color on live birds. We question the assumption that their field measurements represent true color and highlight concerns regarding their experimental design and methodology. Because they did not measure color of live birds in the lab or the color of plucked feathers in the field, they cannot directly test whether the assessment of color in the field on a live bird is superior. Also, rather than assume field measures are the most accurate or precise way to assess plumage color, we suggest cross-validation with other methodologies, such as digital photography, pigment biochemistry, or measures of a known color standard in both environments. Importantly, researchers should be aware of the limitations and advantages of various methods for measuring plumage color so they can use the method most appropriate for their study. Vaquero-Alba y sus colaboradores publicaron un estudio en The Auk comparando medidas objetivas del color del plumaje tomadas en el campo directamente en el cuerpo del ave con medidas tomadas en el laboratorio en plumas recolectadas y organizadas para emular la apariencia natural del plumaje. Aunque las medidas de campo del color del plumaje fueron menos repetibles que las de laboratorio, los autores concluyeron que las medidas tomadas en el campo fueron ma´s representativas del ‘‘color verdadero’’ de un ave. En consecuencia, recomendaron que los investigadores deben llevar espectrofot ´ ometros a los sitios de campo para medir el color en aves vivas. Cuestionamos la suposici ´on de que sus mediciones de campo representan el ‘‘color verdadero’’ y resaltamos nuestras preocupaciones con respecto a su dise ˜no experimental y metodolog´ıa. Debido a que ellos no midieron el color de las aves vivas en el laboratorio ni el color de las plumas sueltas en el campo, no pueden evaluar directamente si la evaluaci ´on del color en el campo en un ave viva es superior. Tambi´en, en vez de asumir que las medidas de campo son la forma ma´s exacta o precisa de determinar el color del plumaje, sugerimos que se haga una validaci ´on cruzada con otras metodolog´ıas como la fotograf´ıa digital, la bioqu´ımica de los pigmentos o las medidas de un esta´ndar de un color conocido en ambos ambientes. Es importante que los investigadores tengan en cuenta las limitaciones y avances en varios m´etodos para medir el color del plumaje para que puedan usar el m´etodo ma´s apropiado para su estudio

The importance of cross-validation, accuracy, and precision for measuring plumage color: A comment on Vaquero-Alba et al. (2016)

Vaquero-Alba and colleagues published a study in The Auk: Ornithological Advances comparing objective color measurements of plumage taken in the field directly on a bird’s body to those taken in the lab on collected feathers arranged to emulate the appearance of a bird’s natural plumage. Although the field measures of plumage color were less repeatable than lab measures, the authors concluded that measurements taken in the field were more representative of a bird’s ‘‘true color.’’ Accordingly, they recommend that researchers should bring spectrophotometers into the field to measure color on live birds. We question the assumption that their field measurements represent true color and highlight concerns regarding their experimental design and methodology. Because they did not measure color of live birds in the lab or the color of plucked feathers in the field, they cannot directly test whether the assessment of color in the field on a live bird is superior. Also, rather than assume field measures are the most accurate or precise way to assess plumage color, we suggest cross-validation with other methodologies, such as digital photography, pigment biochemistry, or measures of a known color standard in both environments. Importantly, researchers should be aware of the limitations and advantages of various methods for measuring plumage color so they can use the method most appropriate for their study. Vaquero-Alba y sus colaboradores publicaron un estudio en The Auk comparando medidas objetivas del color del plumaje tomadas en el campo directamente en el cuerpo del ave con medidas tomadas en el laboratorio en plumas recolectadas y organizadas para emular la apariencia natural del plumaje. Aunque las medidas de campo del color del plumaje fueron menos repetibles que las de laboratorio, los autores concluyeron que las medidas tomadas en el campo fueron ma´s representativas del ‘‘color verdadero’’ de un ave. En consecuencia, recomendaron que los investigadores deben llevar espectrofot ´ ometros a los sitios de campo para medir el color en aves vivas. Cuestionamos la suposici ´on de que sus mediciones de campo representan el ‘‘color verdadero’’ y resaltamos nuestras preocupaciones con respecto a su dise ˜no experimental y metodolog´ıa. Debido a que ellos no midieron el color de las aves vivas en el laboratorio ni el color de las plumas sueltas en el campo, no pueden evaluar directamente si la evaluaci ´on del color en el campo en un ave viva es superior. Tambi´en, en vez de asumir que las medidas de campo son la forma ma´s exacta o precisa de determinar el color del plumaje, sugerimos que se haga una validaci ´on cruzada con otras metodolog´ıas como la fotograf´ıa digital, la bioqu´ımica de los pigmentos o las medidas de un esta´ndar de un color conocido en ambos ambientes. Es importante que los investigadores tengan en cuenta las limitaciones y avances en varios m´etodos para medir el color del plumaje para que puedan usar el m´etodo ma´s apropiado para su estudio

Opposing Responses to Scarcity Emerge from Functionally Unique Sociality Drivers

From biofilms to whale pods, organisms across taxalive in groups, thereby accruing numerous diverse benefits of soci-ality. All social organisms, however, pay the inherent cost of in-creased resource competition. One expects that when resources be-come scarce, this cost will increase, causing group sizes to decrease.Indeed, this occurs in some species, but there are also species forwhich group sizes remain stable or even increase under scarcity.What accounts for these opposing responses? We present a concep-tual framework, literature review, and theoretical model demon-strating that differing responses to sudden resource shifts can beexplained by which sociality benefit exerts the strongest selectionpressure on a particular species. We categorize resource-relatedbenefits of sociality into six functionally distinct classes and modeltheir effect on the survival of individuals foraging in groups underdifferent resource conditions. Wefind that whether, and to what de-gree, the optimal group size (or correlates thereof) increases, de-creases, or remains constant when resource abundance declinesdepends strongly on the dominant sociality mechanism. Existingdata, although limited, support our model predictions. Overall,we show that across a wide diversity of taxa, differences in howgroup size shifts in response to resource declines can be driven bydifferences in the primary benefits of sociality.publishedVersionPaid open acces

Experimental manipulation of a signal trait reveals complex phenotype-behaviour coordination

Abstract Animals use morphological signals such as ornamental traits or weaponry to mediate social interactions, and the extent of signal trait elaboration is often positively associated with reproductive success. By demonstrating relationships between signal traits and fitness, researchers often make inferences about how behaviour operates to shape those outcomes. However, detailed information about fine-scale individual behaviour, and its physiological basis, can be difficult to obtain. Here we show that experimental manipulations to exaggerate a signal trait (plumage colour) and concomitant changes in testosterone and stress-induced corticosterone levels altered social interactivity between manipulated males and their social mates. On average, darkened males did not have higher levels of interactivity than unmanipulated males; however, males who experienced a greater shift in colour (pale to dark), a larger, positive change in testosterone levels, and a dampened stress-induced corticosterone response had a larger increase in the number of interactions with their social mate post-manipulation compared to pre-manipulation. This work provides new insights into the integration and real-time flexibility of multivariate phenotypes and direct evidence for the role of social interactions in pair bond maintenance

A multivariate view of the speciation continuum

The concept of a “speciation continuum” has gained popularity in recent decades. It emphasizes speciation as a continuous process that may be studied by comparing contemporary population pairs that show differing levels of divergence. In their recent perspective article in Evolution, Stankowski and Ravinet provided a valuable service by formally defining the speciation continuum as a continuum of reproductive isolation, based on opinions gathered from a survey of speciation researchers. While we agree that the speciation continuum has been a useful concept to advance the understanding of the speciation process, some intrinsic limitations exist. Here, we advocate for a multivariate extension, the speciation hypercube, first proposed by Dieckmann et al. in 2004, but rarely used since. We extend the idea of the speciation cube and suggest it has strong conceptual and practical advantages over a one-dimensional model. We illustrate how the speciation hypercube can be used to visualize and compare different speciation trajectories, providing new insights into the processes and mechanisms of speciation. A key strength of the speciation hypercube is that it provides a unifying framework for speciation research, as it allows questions from apparently disparate subfields to be addressed in a single conceptual model

Transforming graduate training in STEM education

The need for improved instruction in college science, technology, engineering, and math (STEM) courses is a prominent national policy issue (Brewer and Smith 2011, Olson and Riordan 2012). To address this need, instruction in many college STEM courses is being revolutionized through the adoption of student-centered evidence-based teaching practices. There is a growing body of literature on how to employ these techniques and on the benefits of using empirically validated teaching practices in college classrooms (Handelsman et al. 2004, Allen and Tanner 2005, Haak2011). The majority of efforts in STEM education transformation are directed at faculty, while graduate student training in these practices has not kept pace. Pre-service faculty (i.e. graduate students) should receive training in pedagogy from the beginning of their education (Bouwma-Gearhart et al. 2007), just as K–12 science teachers receive professional development in both the pre-service and in-service stages of their careers. Offering graduate students more training in pedagogy and meaningful opportunities for practice throughout their graduate careers will benefit not only graduate students as they enter the workforce, but also the undergraduates and faculty at their institutions

Non-Steroidal Anti-Inflammatory Drugs in Alzheimer\u27s Disease and Parkinson\u27s Disease: Reconsidering the Role of Neuroinflammation

Alzheimer\u27s disease (AD) and Parkinson\u27s disease (PD) are the most common neurodegenerative diseases with age as the greatest risk factor. As the general population experiences extended life span, preparation for the prevention and treatment of these and other age-associated neurological diseases are warranted. Since epidemiological studies suggested that non-steroidal anti-inflammatory drug (NSAID) use decreased risk for AD and PD, increasing attention has been devoted to understanding the costs and benefits of the innate neuroinflammatory response to functional recovery following pathology onset. This review will provide a general overview on the role of neuroinflammation in these neurodegenerative diseases and an update on NSAID treatment in recent experimental animal models, epidemiological analyses, and clinical trials

Data from: Phenotypic differentiation is associated with divergent sexual selection among closely related barn swallow populations

Sexual selection plays a key role in the diversification of numerous animal clades and may accelerate trait divergence during speciation. However, much of our understanding of this process comes from phylogenetic comparative studies, which rely on surrogate measures such as dimorphism that may not represent selection in wild populations. In this study, we assess sexual selection pressures for multiple male visual signals across four barn swallow (Hirundo rustica) populations. Our sample encompassed 2400 linear km and two described subspecies: European H. r. rustica (in the Czech Republic and Romania) and Eastern Mediterranean H. r. transitiva (in Israel), as well as a potential area of contact (in Turkey). We demonstrate significant phenotypic differentiation in four sexual signaling axes, despite very low-level genomic divergence and no comparable divergence in an ecological trait. Moreover, the direction of phenotypic divergence is consistent with differences in sexual selection pressures among subspecies. Thus, H. r. transitiva, which have the darkest ventral plumage of any population, experience directional selection for darker plumage. Similarly, H. r. rustica, which have the longest tail feathers of any population, experience directional selection for elongated tail feathers and disruptive selection for ventral plumage saturation. These results suggest that sexual selection is the primary driver of phenotypic differentiation in this species. Our findings add to growing evidence of phenotypic divergence with gene flow. However, to our knowledge, this is the first study to relate direct measures of the strength and targets of sexual selection to phenotypic divergence among closely-related wild populations