Search

Sexual signals are often transmitted through multiple modalities (e.g., visual and chemical) and under selection from both intended and unintended receivers. Each component of a multimodal signal may be more or less conspicuous to receivers, and signals may evolve to take advantage of available private channels. We recently documented percussive substrate-borne vibrations in the Pacific field cricket (Teleogryllus oceanicus), a species that uses airborne acoustic and chemical signals to attract and secure mates. The airborne signals of Hawaiian T. oceanicus are currently undergoing rapid evolution; at least five novel male morphs have arisen in the past 20 years. Nothing is yet known about the newly discovered percussive substrate-borne vibrations, so we ask “how” they are produced, “who” produces them (e.g., population, morph), “when” they produce them (e.g., whether they are plastic), and “why” (e.g., do they play a role in mating). We show that the vibrations are produced exclusively by males during courtship via foreleg drumming. One novel morph, purring, produces quieter airborne songs and is more likely to drum than the ancestral morph. However, drumming behavior is also contextually plastic for some males; when we removed the ability of males to produce airborne song, ancestral males became more likely to drum, whereas two novel morphs were equally likely to drum regardless of their ability to produce song. Opposite our prediction, females were less likely to mate with males who drummed. We discuss why that might be and describe what we can learn about complex signal evolution from this newly discovered behavior.

Course-based undergraduate research experiences (CUREs) are high-impact practices that allow students to conduct research during class time. Benefits of a CURE can be maximized when integrated into a faculty member’s ongoing research. However, this can be particularly challenging for field biologists, especially when field sites are not situated near their university. Indeed, few existing CUREs are field based. One solution is to partner with a collaborator near the field site. We describe a semester-long CURE in an animal behavior class that involved collaboration among three institutions: researchers from two “distant” institutions have ongoing research at the “local” institution where the CURE took place. This model uses remote conferencing and strategic collaboration to meet all stakeholders’ needs. Undergraduate students engaged as active participants in collaborative inquiry-based work, learned in a cooperative context, and even participated in the publication process. The local principal investigator and their institution generated a high-impact course that integrated research and teaching. Likewise, the distant principal investigators were able to collect more extensive and longer-term field-based data than otherwise possible, and they gained valuable input from the local researchers that contributed to future projects. Remote collaborations open the door to international collaboration with smaller institutions, promoting greater inclusion in science.

While thought to be widely used for animal communication, substrate-borne vibration is relatively unexplored compared to other modes of communication. Substrate-borne vibrations are important for mating decisions in many orthopteran species, yet substrate-borne vibration has not been documented in the Pacific field cricket Teleogryllus oceanicus. Male T. oceanicus use wing stridulation to produce airborne calling songs to attract females and courtship songs to entice females to mate. A new male morph has been discovered, purring crickets, which produce much quieter airborne calling and courtship songs than typical males. Purring males are largely protected from a deadly acoustically orienting parasitoid fly, and they are still able to attract female crickets for mating though typical calling song is more effective for attracting mates. Here, we document the first record of substrate-borne vibration in both typical and purring male morphs of T. oceanicus. We used a paired microphone and accelerometer to simultaneously record airborne and substrate-borne sounds produced during one-on-one courtship trials in the field. Both typical and purring males produced substrate-borne vibrations during courtship that temporally matched the airborne acoustic signal, suggesting that the same mechanism (wing movement) produces both sounds. As previously established, in the airborne channel, purring males produce lower amplitude but higher peak frequency songs than typical males. In the vibrational channel, purring crickets produce songs that are higher in peak frequency than typical males, but there is no difference in amplitude between morphs. Because louder songs (airborne) are preferred by females in this species, the lack of difference in amplitude between morphs in the substrate-borne channel could have implications for mating decisions. This work lays the groundwork for investigating variation in substrate-borne vibrations in T. oceanicus, intended and unintended receiver responses to these vibrations, and the evolution of substrate-borne vibrations over time in conjunction with rapid evolutionary shifts in the airborne acoustic signal.

Genital morphology exhibits tremendous variation and is intimately linked with fitness. Sexual selection, nonmating natural selection and neutral forces have been explored as potential drivers of genital divergence. Though less explored, genitalia may also be plastic in response to the developmental environment. In poeciliid fishes, the length of the male intromittent organ, the gonopodium, may be driven by sexual selection if longer gonopodia attract females or aid in forced copulation attempts or by nonmating natural selection if shorter gonopodia allow predator evasion. The rearing environment may also affect gonopodium development. Using an experimental introduction of Trinidadian guppies into four replicate streams with reduced predation risk, we tested whether this new environment caused the evolution of genitalia. We measured gonopodium length after rearing the source and introduced populations for two generations in the laboratory to remove maternal and other environmental effects. We split full-sibling brothers into different rearing treatments to additionally test for developmental plasticity of gonopodia in response to predator cues and food levels as well as the evolution of plasticity. The introduced populations had shorter gonopodia after accounting for body size, demonstrating rapid genital evolution in 2-3 years (8-12 generations). Brothers reared on low food levels had longer gonopodia relative to body size than those on high food, reflecting maintenance of gonopodium length despite a reduction in body size. In contrast, gonopodium length was not significantly different in response to the presence or absence of predator cues. Because the plastic response to low food was maintained between the source and introduced populations, there was no evidence that plasticity evolved. This study demonstrates the importance of both evolution and developmental plasticity in explaining genital variation.

Titles from entomology and ecology journals were analysed, testing the effect of Latin and common names, functional groups, geographic location, question marks, humour, and title length on citation rate. Using the Latin names of study organisms in a title decreases a paper's citation rate. There was no effect of the use of common names, question marks, humour, or title length on citation rate. Effects of functional group and geographic location were variable.

The diversity of signalling traits within and across taxa is vast and striking, prompting us to consider how novelty evolves in the context of animal communication. Sexual selection contributes to diversification, and here we endeavour to understand the initial conditions that facilitate the maintenance or elimination of new sexual signals and receiver features. New sender and receiver variants can occur through mutation, plasticity, hybridization and cultural innovation, and the initial conditions of the sender, the receiver and the environment then dictate whether a novel cue becomes a signal. New features may arise in the sender, the receiver or both simultaneously. We contend that it may be easier than assumed to evolve new sexual signals because sexual signals may be arbitrary, sexual conflict is common and receivers are capable of perceiving much more of the world than just existing sexual signals. Additionally, changes in the signalling environment can approximate both signal and receiver changes through a change in transmission characteristics of a given environment or the use of new environments. The Anthropocene has led to wide-scale disruption of the environment and may thus generate opportunity to directly observe the evolution of new signals to address questions that are beyond the reach of phylogenetic approaches.

Climatic conditions can be very heterogeneous even over small geographic scales, and are believed to be major determinants of the abundance and distribution of species and populations. Organisms are expected to evolve in response to the frequency and magnitude of local thermal extremes, resulting in local adaptation. Using replicate yellow dung fly (Scathophaga stercoraria; Diptera: Scathophagidae) populations from cold (northern Europe) and warm climates (southern Europe), we compared 1) responses to short-term heat and cold shocks in both sexes, 2) heat shock protein (Hsp70) expression in adults and eggs, and 3) female reproductive traits when facing short-term heat stress during egg maturation. Contrary to expectations, thermal traits showed minor geographic differentiation, with weak evidence for greater heat resistance of southern flies but no differentiation in cold resistance. Hsp70 protein expression was little affected by heat stress, indicating systemic rather than induced regulation of the heat stress response, possibly related to this fly group's preference for cold climes. In contrast, sex differences were pronounced: males (which are larger) endured hot temperatures longer, while females featured higher Hsp70 expression. Heat stress negatively affected various female reproductive traits, reducing first clutch size, overall reproductive investment, egg lipid content, and subsequent larval hatching. These responses varied little across latitude but somewhat among populations in terms of egg size, protein content, and larval hatching success. Several reproductive parameters, but not Hsp70 expression, exhibited heritable variation among full-sib families. Rather than large-scale clinal geographic variation, our study suggests some local geographic population differentiation in the ability of yellow dung flies to buffer the impact of heat stress on reproductive performance.

Evolution education in the United States remains controversial and challenging. This is in part due to the difficulty educators face when trying to overcome students' preexisting beliefs about evolution, which can bias assimilation of information and inhibit learning. We propose that the most effective way to overcome such belief persistence is through an engaging, hands-on inquiry approach that mimics the scientific process used to study evolution. Although this teaching approach, known as authentic science, has gained recognition for its effectiveness in the classroom, it has not been widely applied to teach evolution. We describe how an authentic science approach can be used to teach evolution by natural selection, and provide a formula for the development of such programs. Following this blueprint, we developed a program using Trinidadian guppies and implemented it in 7th grade classrooms in Colorado. Pre- and post-program assessments revealed significant increases in both the understanding and acceptance of evolution among participants. Authentic science experiments using locally adapted populations of live organisms may be able to overcome belief persistence and improve student understanding of evolution.

Evolution education poses unique challenges because students can have preconceptions that bias their learning. Hands-on, inquiry approaches can help overcome preset beliefs held by students, but few such programs exist and teachers typically lack access to these resources. Experiential learning in the form of self-guided kits can allow evolution education programs to maximize their reach while still maintaining a high-quality resource. We created an inquiry-based kit that uses live Trinidadian guppies to teach evolution by natural selection using the VIST (Variation, Inheritance, Selection, Time) framework. Our collaborative team included evolutionary biologists and education specialists, and we were able to combine expertise in evolution research and inquiry-based kit design in the development of this program. By constructing the kits with grant funds slated for broader impacts and maintaining them at our university's Education and Outreach Center, we made these kits freely available to local schools over the long term. Students and teachers have praised how clearly the kits teach evolution by natural selection, and we are excited to share this resource with readers of The American Biology Teacher.

Theory predicts that gene flow will decrease phenotypic differences among populations. Correlational studies have in some cases documented constraining effects of gene flow on phenotypic divergence and/or have also provided evidence for local differentiation despite high gene flow. However, correlative studies are unable to evaluate how gene flow affects genetically based phenotypic divergence or the extent to which gene flow constrains adaptive divergence. Translocation experiments using Trinidadian guppies provided an opportunity to test the effects of new gene flow on quantitative traits in native recipient populations. We measured a suite of traits in guppies reared in common garden environments before and multiple generations following gene flow from guppies that originated from a different environment. We interpreted our results in light of a priori predictions based on evolutionary theory and extensive background information about guppies and our focal populations. Although we could not include a s...

The study of Animal Behavior is critically important in understanding our living world and is a major program within the NSF. For students, animal behavior projects offer the opportunity to explore original questions in a scientifically rigorous manner. However, animal behavior projects are under-represented in science fairs and are often discouraged by teachers and judges. We give a sample of the types of questions that students could explore and we suggest appropriate judging criteria.

Ethnically and gender diverse groups are more efficient, creative, and productive than homogeneous groups, yet women and minorities are underrepresented in the science, technology, engineering, and mathematics (STEM) workforce. One contributor is unequal access to high-quality STEM education based on socioeconomic status and race, which we may be able to address through inquiry-based out-of-school time programs. Here we describe a 6-month after-school program that allows an underrepresented community of middle school students to conduct original scientific research that they present at a conference each year. Through qualitative assessments and interviews, we found a trend for increased interest in STEM careers and self-efficacy in participants. Self-efficacy, or belief in one’s ability to succeed, predicts performance and persistence in STEM. Both self-efficacy and interest in STEM careers increased after students presented their research at a conference, highlighting the unexplored importance of dissemination for shaping self-efficacy in K-12 students. Small after-school programs like ours can be easily accomplished as broader impacts by scientists, and well-designed programs have the potential to positively affect change by increasing access and participation in STEM for diverse students.

Significant resources go toward rearing and stocking fish globally, yet poststocking survival is often low, largely due to high predation rates on hatchery-reared fish. Antipredator behavior has been enhanced in many species through exposure to chemical cues that simulate predation events, but the implementation of such protocols may be logistically challenging. It has been suggested that a single exposure of hatchery fish to chemical cues while en route to stocking locations may be sufficient to enhance antipredator behavior and improve survival. We tested whether a one-time exposure to conspecific alarm cues while en route to a stocking site increased poststocking survival of three strains of rainbow trout (Oncorhynchus mykiss (Walbaum, 1792)). We found no difference in mortality rates between strains or between treatment fish (exposed to alarm cues) and control fish (not exposed to alarm cues), suggesting that this quick and easy protocol was insufficient and that more complex techniques should be explored to increase poststocking survival.

Fisheries management agencies allocate significant proportions of available resources to rear fish for stocking in lakes, rivers, and reservoirs. However, domesticated fish reared in a hatchery environment may fail to exhibit normal antipredator behavior and can have relatively low survival when released into natural habitats. Exposing hatchery fish to natural predator cues can provide information about their capacity to exhibit appropriate behavioral responses and has the potential to enhance antipredator behavior and subsequent survival in the wild. We investigated immediate behavioral responses to an acute exposure to chemical cues of predation in highly domesticated, hatchery-reared rainbow trout Oncorhynchus mykiss. We used a frequently stocked and economically important strain of rainbow trout, the German Rainbow (GR), which is resistant to whirling disease but particularly susceptible to predation. We exposed individual rainbow trout to alarm cues from conspecifics, kairomones from brown trout Salmo trutta predators, and a combination of the two cues. Fish exposed to these cues exhibited changes in behavior expected to reduce predation risk, including a reduction in time spent actively swimming and exploring, and an increase in time spent frozen. Thus, these highly domesticated, hatchery-reared fish retain the innate ability to express appropriate responses to the threat of predation. Future research should investigate whether repeated exposure to predation cues in a hatchery setting could translate to long-term enhancement of antipredator behavior and increased survival rates, as this would provide a rapid, simple and low cost way to increase the efficiency of stocking programs for recreational purposes and, more importantly, native fish restoration and conservation.

Human land use is fragmenting habitats worldwide and inhibiting dispersal among previously connected populations of organisms, often leading to inbreeding depression and reduced evolutionary potential in the face of rapid environmental change. To combat this augmentation of isolated populations with immigrants is sometimes used to facilitate demographic and genetic rescue. Augmentation with immigrants that are genetically and adaptively similar to the target population effectively increases population fitness, but if immigrants are very genetically or adaptively divergent, augmentation can lead to outbreeding depression. Despite well-cited guidelines for the best practice selection of immigrant sources, often only highly divergent populations remain, and experimental tests of these riskier augmentation scenarios are essentially nonexistent. We conducted a mesocosm experiment with Trinidadian guppies (Poecilia reticulata) to test the multigenerational demographic and genetic effects of augmenting 2 target populations with 3 types of divergent immigrants. We found no evidence of demographic rescue, but we did observe genetic rescue in one population. Divergent immigrant treatments tended to maintain greater genetic diversity, abundance, and hybrid fitness than controls that received immigrants from the source used to seed the mesocosms. In the second population, divergent immigrants had a slightly negative effect in one treatment, and the benefits of augmentation were less apparent overall, likely because this population started with higher genetic diversity and a lower reproductive rate that limited genetic admixture. Our results add to a growing consensus that gene flow can increase population fitness even when immigrants are more highly divergent and may help reduce uncertainty about the use of augmentation in conservation.

Lateralized brain function, or partitioning of tasks to separate hemispheres of the brain, directly impacts behaviour and fitness. Highly lateralized individuals tend to outperform nonlateralized individuals in many survival-related behaviours, such as the ability to learn, escape predators and multitask. Despite these benefits to lateralization, there is a great deal of observed variation in this trait within and between populations that is likely determined by the balance between costs and benefits of laterality in a given environment. Laterality appears to be heritable, but it can also vary with the environment experienced during development. We investigated the role of evolutionary history and developmental plasticity in determining the degree of laterality in the Trinidadian guppy, Poecilia reticulata, a freshwater fish that experiences variable predation pressure in its native range. We compared pairs of closely related populations that experience either high or low levels of predation in the wild, and manipulated the perceived predation risk in the rearing environment using a common garden split-brood design. We assayed laterality in mature male guppies using a detour test. Fish reared with exposure to chemical predator cues were more lateralized than their brothers reared without predator cues. This plastic response is in the direction we would predict if lateralization is favoured in environments with high predation risk. However, unlike findings in related species, we did not detect repeatable differences in degree of laterality associated with historical predation regime, suggesting that predation risk experienced over evolutionary history does not shape laterality patterns in guppies. Thus, although it is currently underemphasized in the literature, plasticity is likely an important contributor to variation in laterality. © 2014 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

The authors describe their experiences with evolution and science education and how this led to their interest in inquiry-based teaching. Inquiry-based evolution education programs should be effective but are relatively uncommon, likely because of the resources and expertise required to create them. University/K-12 collaborations may be a solution but tend to be limited in their reach. Kit-based teaching allows inquiry-based evolution programs to be more broadly disseminated. Kits may also improve engagement and science self-efficacy since students take ownership of their learning and independently master science tasks. We describe an inquiry-based kit that we developed in collaboration with local teachers and an Education and Outreach Center at Colorado State University. We used three populations of locally adapted fish, Trinidadian guppies, to illustrate important concepts in evolution. Students work through the self-guided kit and booklet to complete inquiry and authentic science experiments and observations. These activities allow them to discover each concept and the definition of evolution at the end of the program. We describe the kit in detail and reflect on the challenges and successes associated with its creation and implementation.

Novel environments often impose directional selection for a new phenotypic optimum. Novel environments, however, can also change the distribution of phenotypes exposed to selection by inducing phenotypic plasticity. Plasticity can produce phenotypes that either align with or oppose the direction of selection. When plasticity and selection are parallel, plasticity is considered adaptive because it provides a better pairing between the phenotype and the environment. If the plastic response is incomplete and falls short of producing the optimum phenotype, synergistic selection can lead to genetic divergence and bring the phenotype closer to the optimum. In contrast, non-adaptive plasticity should increase the strength of selection, because phenotypes will be further from the local optimum, requiring antagonistic selection to overcome the phenotype-environment mismatch and facilitate adaptive divergence. We test these ideas by documenting predator-induced plasticity for resting metabolic rate and growth rate in populations of the Trinidadian guppy (Poecilia reticulata) adapted to high and low predation. We find reduced metabolic rates and growth rates when cues from a predator are present during development, a pattern suggestive of adaptive and non-adaptive plasticity, respectively. When we compared populations recently transplanted from a high-predation environment into four streams lacking predators, we found evidence for rapid adaptive evolution both in metabolism and growth rate. We discuss the implications for predicting how traits will respond to selection, depending on the type of plasticity they exhibit.