Researchers' ability to accurately screen fossil and subfossil specimens for preservation of DNA and protein sequences remains limited. Thermal exposure and geologic age are usable proxies for sequence preservation on a broad scale but are of nominal use for specimens of similar depositional environments. Cell and tissue biomolecular histology is thus proposed as a novel proxy for determining sequence preservation potential of ancient specimens with improved accuracy. Biomolecular histology as a proxy is hypothesized to elucidate why fossils/subfossils of some depositional environments preserve sequences while others do not and to facilitate selection of ancient specimens for use in molecular studies.
Bird feathers serve multiple functions through their physical structure and coloration, but the evolution of functional novelty in bird feathers remains poorly understood. We investigated how selective pressures gave rise to seasonal coloration change in the feathers of the New World Warblers (Aves: Parulidae), a family with a remarkable diversity of plumage, molt, and life history strategies. Seasonal color changes in the plumages of migratory warblers are hypothesized to reflect a tradeoff between natural and sexual selection on the breeding and non-breeding distributions. We used comparative methods including phylogenetic path analysis to examine nested hypotheses relating to the evolution of seasonal dichromatism (i.e. breeding and nonbreeding plumages) and the molts that produce these plumages. We found that biannual molts likely evolved in response to increased feather wear and that changes in feather coloration evolved after the biannual molt itself. These results demonstrate that structural needs, not seasonal selection on coloration, drive the evolution of molt strategies in Parulidae. Importantly, once a biannual molt evolves, it served as a preadaptation for seasonal changes in plumage color. These results reveal how life history strategies act upon multiple and separate feather functions to drive the evolution of feather replacement patterns and bird coloration.
The rapid shift to online teaching in spring 2020 meant most of us were teaching in panic mode. As we move forward with course planning for fall and beyond, we can invest more time and energy into improving the online experience for our students. We advocate that instructors use inclusive teaching practices, specifically through active learning, in their online classes. Incorporating pedagogical practices that work to maximize active and inclusive teaching concepts will be beneficial for all students, and especially those from minoritized or underserved groups. Like many STEM fields, Ecology and Evolution shows achievement gaps and faces a leaky pipeline issue for students from groups traditionally underrepresented in science. Making online classes both active and inclusive will aid student learning and will also help students feel more connected to their learning, their peers, and their campus. This approach will likely help with performance, retention, and persistence of students. In this paper we offer strategies and techniques that weave together active and inclusive teaching practices and challenge faculty to commit to making small changes in the fall as a first step to more inclusive teaching in ecology and evolutionary biology courses.
Team-Based Learning (TBL) is a pedagogical tool that has great potential to develop student engagement, accountability, and equity in the online classroom. TBL is rooted in evidence-based educational theories and practices that underlie many active learning approaches such as self-testing, team discussion, and application of knowledge. The use of these approaches is associated with better student performance, retention, and sense of belonging in the classroom, aspects that are often reported to be especially lacking in online courses. Here, we describe how we implemented TBL in a face-to-face and an online introductory level evolution and biodiversity course. Our experiences using TBL approaches in the online course have been rewarding, students are engaged and accountable for their learning, and performed well in the course. Our goal is to provide an example of how we designed a life science course using TBL approaches and transitioned the course to an online environment. With the current switch to remote instruction and online learning, we recommend the use of TBL as a course design approach that can improve the students online learning experience.
Climate change and other global change drivers threaten plant diversity in mountains worldwide. A widely documented response to such environmental modifications is for plant species to change their elevational ranges. Range shifts are often idiosyncratic and difficult to generalize, partly due to variation in sampling methods. There is thus a need for a standardized monitoring strategy that can be applied across mountain regions to assess distribution changes and community turnover of native and non-native plant species over space and time. Here, we present a conceptually intuitive and standardized protocol developed by the Mountain Invasion Research Network (MIREN) to systematically quantify global patterns of native and non-native species distributions along elevation gradients and shifts arising from interactive effects of climate change and human disturbance. Usually repeated every five years, surveys consist of 20 sample sites located at equal elevation increments along three replicate roads per sampling region. At each site, three plots extend from the side of a mountain road into surrounding natural vegetation. The protocol has been successfully used in 18 regions worldwide from 2007 to present. Analyses of one point in time already generated some salient results, and revealed region-specific elevational patterns of native plant species richness, but a globally consistent elevational decline in non-native species richness. Non-native plants were also more abundant directly adjacent to road edges, suggesting that disturbed roadsides serve as a vector for invasions into mountains. From the upcoming analyses of time series even more exciting results especially about range shifts can be expected. Implementing the protocol in more mountain regions globally would help to generate a more complete picture of how global change alters species distributions. This would inform conservation policy in mountain ecosystems, where some conservation policies remain poorly implemented.
1. Teleost fishes occupy a range of ecosystem and habitat types subject to large seasonal fluctuations. Temperate fishes in particular, survive large shifts in temperature, light availability, and access to certain habitats across seasons. Yet, there is limited understanding of how behavioral responses to a seasonally shifting environment might shape, or be shaped by, the nervous system. 2. Here we quantified variation in relative brain size and the size of five externally visible brain regions in a freshwater top predator, lake trout (Salvelinus namaycush), across six consecutive seasons in two different lakes. Acoustic telemetry data from one of our study lakes was collected during the study period from a different subset of individuals and used to infer relationships between brain size and seasonal behaviors (habitat use and movement rate). 3. Our results indicated that lake trout relative brain size was larger in the fall and winter compared to the spring and summer in both lakes. Larger brains coincided with increased use of nearshore lake habitats and increased horizontal movement rates by lake trout in the fall and winter based on acoustic telemetry. The telencephalon followed the same pattern as whole brain size, while the other brain regions (cerebellum, optic tectum, olfactory bulbs, hypothalamus) were only smaller in the spring. 4. Seasonal shifts in total brain size might reflect greater underlying changes in the size of the telencephalon. These findings provide evidence that flexibility in brain size could underpin shifts in behavior which could subserve functions associated with differential habitat use during cold and warm seasons and allow fish to succeed in seasonally variable temperate environments.
To provide the most comprehensive picture of species phylogeny and phylogeography of European roe deer (Capreolus capreolus), we analysed mtDNA control region (610 bp) of 1469 samples of roe deer from Central and Eastern Europe and included into the analyses additional 1541 mtDNA sequences from GenBank from other regions of the continent. We detected two mtDNA lineages of the species: European and Siberian one (an introgression of C. pygargus mtDNA into C. capreolus). The Siberian lineage was most frequent in eastern part of the continent and declined towards Central Europe. The European lineage contained three clades (Central, Eastern and Western) composed of 2 to 8 subclades, many of which were separated in space. The Western clade appeared to have a discontinuous range from Portugal to Russia. Most of the subclades in the Central and the Eastern clades were under expansion during the Weichselian glacial period before the Last Glacial Maximum (LGM), while the expansion time of the Western clade overlapped with the Eemian interglacial. High genetic diversity of extant roe deer is the result of their survival during the LGM in a large, contiguous range spanning from the Iberian Peninsula to the Caucasus Mts. and in two northern refugia.
To contain transmission of COVID-19, lockdown or strict restriction of people’s mobility outside their residence was imposed worldwide. In Nepal, the first phase of nationwide lockdown was observed from March 24 to July 21, 2020. This sudden halt in human activities brought positive and negative impacts on forests and wildlife. We undertook a study was undertaken to know the impact of the CoViD-19 lockdown on wildlife and forests in the protected areas (PAs) of Nepal. The study was carried in July and September 2020, data of illegal activities recorded by the PAs and also those reported by media were obtained and analyzed. Key Informant Interview (KII) was done with the park officers and security personnel by virtual communication that included telephone, messenger app, and ZOOM video meeting to collect detailed information and for verification. The collected data were categorized into four groups: i) wildlife killed, ii) wildlife injured, iii) arrest incidents related to forest crime, and iv) arrest incidents related to wildlife crime. Data from the fiscal year 2019-2020 were analyzed, comparing before lockdown and after. The study found trends of substantial increases in. wildlife death in two PAs, Banke National Park and Bardia National Park out of 20 during the lockdown. Similarly, Chitwan National Park (CNP) and Shivapuri Nagarjun National Park (SNNP) witnessed a rise in wildlife poaching. CNP and SNNP are located close to highly populated cities and also having human settlements in their peripheries. Interestingly, wildlife was easily sighted inside PAs during the lockdown, presumably because the absence of visitors and human activities during the lockdown decreased disturbance. Thus, a paradoxical situation was observed with the wildlife enjoying the freedom of movement on the one hand, but with poachers, many of them laid off from other activities, taking advantage of the lapse in security.
Reconstructing ecological niche evolution can provide insight into the biogeography and diversification of evolving lineages. However, comparative phylogenetic methods can infer the history of ecological niche evolution inaccurately because (1) species’ niches are often poorly characterized; and (2) phylogenetic comparative methods rely on niche summary statistics rather than full estimates of species’ environmental tolerances. Here we propose a new framework for coding ecological niches and reconstructing their evolution that explicitly acknowledges and incorporates the uncertainty introduced by incomplete niche characterization. Then, we modify existing ancestral state inference methods to leverage full estimates of environmental tolerances. We provide a worked empirical example of our method, investigating ecological niche evolution in the New World orioles (Aves: Passeriformes: Icterus spp.). Temperature and precipitation tolerances were generally broad and conserved among orioles, with niche reduction and specialization limited to a few terminal branches. Tools for performing these reconstructions are available in a new R package called nichevol.
This spring, instructors moved their courses online in an emergency fashion as campuses were closed due to the pandemic. As colleges prepare for the next academic year, there is a need to provide flexible instruction that is more intentional for quality online learning. We taught two undergraduate courses online for the first time this spring and surveyed our students’ reactions to the course experiences. From our experiences and student feedback we identified design elements and activities that were beneficial in promoting student engagement, sense of connectivity, and learning. We describe four qualities for a successful transition to online learning: 1) big questions and core concepts; 2) peer groups including reflective writing; 3) outreach to broader scientific community; and 4) instructor’s social presence in the class. Our experience gives us confidence that courses can be redesigned for online without compromising rigor or essential learning goals.
Education in ecology and evolution often utilizes field instruction to teach key learning outcomes. Remote teaching of learning outcomes that have been traditionally taught in the field, necessitated by the COVID-19 pandemic, presents unique challenges for students, instructors, and institutions. A survey of 117 faculty conducted during spring 2020 revealed substantial reduction of learning outcomes typically taught in the field, and frequent substitutions of less active and more instructor-centered remote activities for field activities. The survey revealed generally negative instructor views on many remote teaching substitutions, yet also showed several approaches that instructors regarded as more effective, despite potential challenges with equitably teaching them. I suggest several models of remote substitutions for traditional field teaching of identification, field techniques, data collection, and study design in the context of the results of this survey.
We conducted a comprehensive analysis of the phylogenetic, phylogeographic, and demographic relationships of Caspian cobra (Naja oxiana; Eichwald, 1831) populations based on a concatenated dataset of two mtDNA genes (cyt b and ND4) across the species’ range in Iran, Afghanistan, and Turkmenistan, along with other members of Asian cobras (i.e. subgenus Naja Laurenti, 1768). Our results provided strong support that N. oxiana is monophyletic and its divergence from its sister taxon, N. kaouthia, during early Pleistocene. Our results also highlight the existence of only one major evolutionary lineage in the Trans-Caspian region, suggesting a rapid expansion of the Caspian cobra from eastern to western Asia, coupled with a rapid range expansion from east of Iran to the northeast. However, the subdivision of eastern and northeastern populations in Iran was not supported; hence we propose only one evolutionary significant unit across the Iranian range of N. oxiana to be considered for conservation efforts.
Knowing the abundance of a population is a crucial component to assess its conservation status and develop effective conservation plans. For most cetaceans, abundance estimation is difficult given their cryptic and mobile nature, especially when the population is small and has a transnational distribution. In the Baltic Sea, the number of harbour porpoises (Phocoena phocoena) has collapsed since the mid-20th century and the Baltic Proper harbour porpoise is listed as Critically Endangered by the IUCN; however, its abundance remains unknown. Here, one of the largest ever passive acoustic monitoring studies was carried out by eight Baltic Sea nations to estimate the abundance of the Baltic Proper harbour porpoise for the first time. By logging porpoise echolocation signals at 298 stations during May 2011-April 2013, calibrating the loggers’ spatial detection performance at sea, and measuring the click rate of tagged individuals, we estimated an abundance of 66-1,143 individuals (95% CI, point estimate 490) during May-October within the population’s proposed management border. The small abundance estimate strongly supports that the Baltic Proper harbour porpoise is facing an extremely high risk of extinction, and highlights the need for immediate and efficient conservation actions through international cooperation. It also provides a starting point in monitoring the trend of the population abundance to evaluate the effectiveness of management measures and determine its interactions with the larger neighbouring Belt Sea population. Further, we offer evidence that design-based passive acoustic monitoring can generate reliable estimates of the abundance of rare and cryptic animal populations across large spatial scales.
Research hypotheses have been a cornerstone of science since before Galileo. Many have argued that inclusion of multiple hypotheses (1) encourage discovery of mechanisms, and (2) reduce bias – both features that should increase transferability and reproducibility. However, we are entering a new era of big data and highly predictive models where some argue the hypothesis is outmoded. Indeed, using a detailed literature analysis, we found prevalence of hypotheses in eco-evo research is very low (6.7-26%) and static from 1990-2015, a pattern mirrored in an extensive literature search (N=302,558 articles). Our literature review also indicates that neither grant success or citation rates were related to the inclusion of hypotheses, which may provide disincentive for hypothesis formulation. Here we confront common justifications for avoiding hypotheses and present new arguments based on benefits to the individual. Although hypotheses are not always necessary, we expect their continued and increased use will help our fields move toward greater understanding, reproducibility, prediction, and effective conservation of nature.
Alternative reproductive tactics (ARTs) have provided valuable insights into how sexual selection and life history tradeoffs can lead to variation within a sex. However, the possibility that tactics may constrain evolution through intralocus tactical conflict (IATC) is rarely considered. In addition, when IATC has been considered, the focus has often been on the genetic correlations between the ARTs, while evidence that the ARTs have different optima for associated traits and that at least one of the tactics is not at its optima is often missing. Here we investigate selection on three traits associated with the ARTs in the swordtail fish Xiphophorus multilineatus; body size, body shape and the sexually selected trait for which these fishes were named, sword length (elongation of the caudal fin). All three traits are tactically dimorphic, with courter males being larger, deeper bodied and having longer swords, and the sneaker males being smaller, more fusiform and having shorter swords. Using measures of reproductive success in a wild population we calculated selection differentials, linear and quadratic gradients, demonstrate that the tactics have different optima and at least one of the tactics is not at its optima for body size and sword length. Our results provide the first evidence of selection in the wild on the sword, an iconic trait for sexual selection. In addition, given the high probability that these traits are genetically correlated to some extent between the two tactics, our study suggests that IATC is constraining both body size and the sword from reaching their phenotypic optima. We discuss the importance of considering the role of IATC in the evolution of tactical dimorphism, how this conflict can be present despite tactical dimorphism, and how it is important to consider this conflict when explaining not only variation within a species but differences across species as well.
The usage of preprint servers in ecology and evolution is increasing, as it allows for research to be rapidly disseminated and available through open access at no cost. This is relevant for Early Career Researchers (ECRs), who must demonstrate research ability for funding opportunities, scholarships, grants, or faculty positions in short temporal windows in order to advance their careers. Concurrently, limited experience with the peer review process can make it challenging for those who are in the early stages of their research career to build publication records. Therefore, ECRs face different challenges relative to researchers with permanent positions and established research programs and have different requirements in terms of research output and timelines. These challenges might also vary according to institution size and country, which are associated with the availability of funding for open access journals. Herein, we hypothesize that career stage and institution size impact relative usage of preprint servers among researchers in ecology and evolution. Using data collected from 500 articles (100 from each of two open access journals, two closed access journals, and a preprint server), we demonstrate that ECRs generate more preprints relative to non-ECRs, for both first and last authors. We speculate that this pattern is reflective of the advantages of quick and open access research that is disproportionately beneficial to ECRs. There is also a marginal effect of first author institution size on preprint usage, whereby the number of preprints tends to increase with institution size for ECRs, although the interaction between ECR status and institution size was not significant. The United States and United Kingdom contributed the greatest number of preprints by early career researchers, whereas non-western countries contributed relatively fewer preprints. This research provides empirical evidence regarding motivations of preprint usage and barriers surrounding large-scale adoption of preprinting in ecology and evolution.
1. Ongoing intensification and fragmentation of European agricultural landscapes dramatically reduce biodiversity and associated functions. To sustain ecosystem services such as ant mediated pest control, the enhancement of perennial non-crop areas holds great potential. 2. To study the potential of newly established grasslands to enhance ant diversity and associated functions, we used hand collection data to investigate differences in ant community composition (a) between cereal crops, old grasslands, and new grassland transects of three years age; (b) depending on ant functional traits; and linked to (c) natural pest control services quantified through predation experiments. 3. Ant species richness did not significantly differ between new and old grasslands, but was significantly higher in grasslands compared to cereal crops. Contrary, ant community composition of new grasslands was more similar to cereal crops and distinct from the species-pool of old grasslands. The functional trait space covered by the ant communities overlapped between old and new grasslands but was extended in the old grasslands. Pest control did not differ significantly between habitat types, and therefore could not be linked to the prevalence of functional traits related to biocontrol services in new grasslands. 4. Our findings show trends of convergence between old and new grasslands, but also indicate that enhancing ant diversity through newly established grasslands takes longer than three years to provide comparable biodiversity and functions. 5. Synthesis and applications Newly established grasslands can increase ant species richness, abundance, and pest control in agroecosystems. However, three years after establishment, new grasslands were still dominated by common agrobiont ant species and lacked habitat specialists present in old grasslands, who require a constant supply of food resources and long colonization times. New grasslands represent a promising measure for enhancing agricultural landscapes but must be preserved in the longer term to sustain biodiversity and associated ecosystem services.
Complex biological traits often originate by integrating previously separate parts, but the organismal functions of these precursors are challenging to infer. If we can understand the ancestral functions of these precursors, it could help explain how they persisted and how they facilitated the origins of complex traits. Animal eyes are some of the best studied complex traits, and they include many parts, such as opsin-based photoreceptor cells, pigment cells, and lens cells. Eye evolution is understood through conceptual models that argue these parts gradually came together to support increasingly sophisticated visual functions. Despite the well accepted logic of these conceptual models, explicit comparative studies to identify organismal functions of eye-precursors are lacking. Here, we investigate how precursors functioned before they became part of eyes in Cnidaria, a group formed by sea anemones, corals and jellyfish. Specifically, we test whether ancestral photoreceptor cells regulated the discharge of cnidocytes, the expensive single-use cells with various uses including prey capture, locomotion, and protection. Similar to a previous study of Hydra, we show an additional four distantly related cnidarian groups discharge significantly more cnidocytes when exposed to dim blue light compared to bright blue light. Our comparative analyses support the hypothesis that the cnidarian ancestor was capable of modulating cnidocyte discharge with light. Although eye-precursors might have had other functions like regulating timing of spawning, our findings are consistent with the hypothesis that photoreceptor cells which mediate cnidocyte discharge predated eyes, perhaps facilitating the prolific origination of eyes in Cnidaria.