Sexual selection can result in the evolution of extreme armaments and ornaments, and the development and maintenance of these traits can come at a considerable cost. These costs have been implicated ...in enforcing an upper limit on trait divergence and promoting condition-dependent traits, such that only individuals in sufficiently high condition can effectively wield these armaments and advertise these ornaments. Numerous studies demonstrate the condition-dependence of sexually selected traits, especially those used by males to advertise to females. In this study, we investigated condition-dependent mating calls in the túngara frog
Physalaemus
(
= Engystomops
)
pustulosus
. We manipulated male condition in the laboratory over a nine-day period by restricting food availability. We then documented: the relationship between male condition (the relative change in body mass from night 1 to night 9) and acoustic parameters of his mating call; how male condition influenced the male’s responses to call playbacks; and finally, how male condition influenced the attractiveness of the male’s calls to females. Males who were not fed during this period showed significant changes in call frequency, duration, and amplitude. In response to playbacks, unfed males called less, and made fewer complex calls. Finally, in phonotaxis experiments, females were more attracted to the calls of unfed males on night 1 to the calls of the same males on night 9. Fed males, on the other hand, showed no significant differences between nights 1 and 9 in call parameters, calling effort, and call attractiveness. This study shows the pervasive effects of condition on three aspects of sexual communication: signal parameters, behavioral response to vocal competition, and mating call attractiveness.
Significance statement
This study shows the widespread effects that an animal’s condition has on its communication system, including: influences on the acoustic parameters of the male’s mating call, their calling effort, and the sexual attractiveness of mating calls to females.
Noise is a common problem in animal communication. We know little, however, about how animals communicate in the presence of noise using multimodal signals. Multimodal signals are hypothesised to be ...favoured by evolution because they increase the efficacy of detection and discrimination in noisy environments. We tested the hypothesis that female túngara frogs' responses to attractive male advertisement calls are improved in noise when a visual signal component is added to the available choices. We tested this at two levels of decision complexity (two and three choices). In a two-choice test, the presence of noise did not reduce female preferences for attractive calls. The visual component of a calling male, associated with an unattractive call, also did not reduce preference for attractive calls in the absence of noise. In the presence of noise, however, females were more likely to choose an unattractive call coupled with the visual component. In three-choice tests, the presence of noise alone reduced female responses to attractive calls and this was not strongly affected by the presence or absence of visual components. The responses in these experiments fail to support the multimodal signal efficacy hypothesis. Instead, the data suggest that audio-visual perception and cognitive processing, related to mate choice decisions, are dependent on the complexity of the sensory scene.
Emitting conspicuous signals into the environment to attract mates comes with the increased risk of interception by eavesdropping enemies. As a defence, a commonly described strategy is for ...signallers to group together in leks, diluting each individual's risk. Lekking systems are often highly social settings in which competing males dynamically alter their signalling behaviour to attract mates. Thus, signalling at the lek requires navigating fluctuations in risk, competition and reproductive opportunities. Here, we investigate how behavioural defence strategies directed at an eavesdropping enemy have cascading effects across the communication network. We investigated these behaviours in the túngara frog (
), examining how a calling male's swatting defence directed at frog-biting midges indirectly affects the calling behaviour of his rival. We found that the rival responds to swat-induced water ripples by increasing his call rate and complexity. Then, performing phonotaxis experiments, we found that eavesdropping fringe-lipped bats (
) do not exhibit a preference for a swatting male compared to his rival, but females strongly prefer the rival male. Defences to minimize attacks from eavesdroppers thus shift the mate competition landscape in favour of rival males. By modulating the attractiveness of signalling prey to female receivers, we posit that eavesdropping micropredators likely have an unappreciated impact on the ecology and evolution of sexual communication systems.
Noise is a common problem in animal communication. We know little, however, about how animals communicate in noise using multimodal signals. Multimodal signals are hypothesized to be favoured by ...evolution because they increase the efficacy of detection/discrimination in noisy environments. We tested the hypothesis that female túngara frogs' responses to attractive male advertisement calls are improved in noise when a visual signal component is added to the available choices. We tested this at two levels of decision complexity (two and three choices). In a two-choice test, the presence of noise did not reduce female preferences for attractive calls. The visual component of a calling male, associated with an unattractive call, also did not reduce preference for attractive calls in the absence of noise. In the presence of noise, however, females were more likely to choose an unattractive call coupled with the visual component. In three-choice tests, the presence of noise alone reduced female responses to attractive calls and this was not strongly affected by the presence or absence of visual components. The responses in these experiments fail to support the multimodal signal efficacy hypothesis. Instead, the data suggest that audio-visual perception and cognitive processing, related to mate choice decisions, are dependent on the complexity of the sensory scene.
Communication facilitates almost every social interaction between organisms and this communication is especially important for mate acquisition. Anuran amphibians are an excellent model system to ...study mate choice behaviors and sexual selection. In this work I recorded male calls of the spring peeper, Pseudacris crucifer, between two populations (Maryland and Louisiana) and analyzed call parameters such as frequency, duration, and rise and fall time. I found differences in the frequency and the frequency sweep of the calls. I conducted choice experiments to test female mating preferences in the Louisiana population and found a preference for longer calls over short calls. Females did not express a preference for frequency, frequency sweep, or local (LA) versus foreign (MD) calls. I also conducted multimodal signaling experiments on the túngara frog, Physalaemus pustulosus. I used natural calls and a robotic túngara frog to determine how females assess different signal modalities (auditory versus visual). I tested previously established attractive calls against unattractive calls, paired with the robo-frog and inflating vocal sac, to see if the visual stimulus would modulate the attractiveness of the call. The presence of the vocal sac did not make the unattractive call more attractive. The vocal sac may have important implications for localization in a more complex environment but here, it did not act as a mate attracting signal. This study provides the ground work necessary for multimodal signaling in spring peepers and for complex sensory environment choice tests in the túngara frog.
Communication facilitates almost every social interaction between organisms and this communication is especially important for mate acquisition. Anuran amphibians are an excellent model system to ...study mate choice behaviors and sexual selection. In this work I recorded male calls of the spring peeper, Pseudacris crucifer, between two populations (Maryland and Louisiana) and analyzed call parameters such as frequency, duration, and rise and fall time. I found differences in the frequency and the frequency sweep of the calls. I conducted choice experiments to test female mating preferences in the Louisiana population and found a preference for longer calls over short calls. Females did not express a preference for frequency, frequency sweep, or local (LA) versus foreign (MD) calls. I also conducted multimodal signaling experiments on the túngara frog, Physalaemus pustulosus. I used natural calls and a robotic túngara frog to determine how females assess different signal modalities (auditory versus visual). I tested previously established attractive calls against unattractive calls, paired with the robo-frog and inflating vocal sac, to see if the visual stimulus would modulate the attractiveness of the call. The presence of the vocal sac did not make the unattractive call more attractive. The vocal sac may have important implications for localization in a more complex environment but here, it did not act as a mate attracting signal. This study provides the ground work necessary for multimodal signaling in spring peepers and for complex sensory environment choice tests in the túngara frog.
The coronavirus disease 2019 (COVID-19) pandemic affected all social systems, but healthcare services were particularly disrupted. The pandemic also had a disproportionate impact on populations made ...socially vulnerable. In this study, we documented the experiences of Latinx sexual and gender minority (SGM) individuals with access to care during COVID-19 stay-at-home orders.
Semistructured qualitative interviews assessing experiences during the stay-at-home orders in response to the COVID-19 pandemic and patients' experiences accessing healthcare during this period were conducted with 21 Latinx SGM individuals from the Washington, DC, area. Data were analyzed using rapid qualitative analysis (RQA), and salient themes were identified.
The RQA revealed 3 themes reflecting participants' experiences with pharmaceutical care during COVID-19 stay-at-home orders: (1) challenges in accessing HIV services; (2) community engagement; and (3) providers supporting access to care. Participants experienced problems with adherence to medication, transportation, and technology, as well as delays in care and miscommunication with providers. Latinx SGM individuals demonstrated engagement in response to this emergency as a community and valued their providers and their efforts to facilitate access to care.
The COVID-19 pandemic strained healthcare services. Findings from this study show that the impact of the pandemic on the provision of care increased the vulnerability of Latinx SGM people. Future research should explore the impact of public health emergencies on the health of populations historically made socially vulnerable, and innovative solutions should be identified to eliminate these barriers to health equity.
Global concerns regarding greenhouse gas emissions combined with soaring oil prices have driven the search for renewable diesel fuels derived from either virgin or waste vegetable oils, dubbed ..."bio-diesels". A key challenge in the emerging bio-diesel industry is cost-effective pre-treatment of waste vegetable oils to reduce free-fatty acid content prior to transesterification. This article reports, for the first time, recoverability and reusability of hydrochloric and sulfuric acid catalysts for efficient pre-treatment of waste cooking oils for subsequent conversion to bio-diesels. Esterification of omega-9 polyunsaturated fatty acids, particularly 18:2,18:3 linoleic acid with methanol and a homogenous acid catalyst was investigated over a range of fatty acid concentrations. It was determined that greater than 95% by weight of each catalyst was recovered after esterification under all conditions investigated. When recovered methanol was used, containing recovered catalyst and water, it was determined that hydrochloric acid catalyzed esterification exhibits a higher tolerance to water accumulation. After sulfuric acid was recovered and re-used, the observed rate constant decreased more than 50% to a value comparable to that observed for hydrochloric acid at more than three times the water concentration.
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