Biology subjects

Creanza, N.

Publications and source records attributed to Creanza, N..

16 recordsLinked to original sources

bioRxiv2026

Song evolution in light of ecosystem differences: exploring effects of urbanization and ecology on temporal and frequency traits of Spotted and Eastern towhee songs

The Eastern towhee (Pipilo erythrophthalmus) and Spotted towhee (Pipilo maculatus) are large New World sparrows found across North America. These two species were previously classified as a single species, the Rufous-sided towhee, which was separated in 1995 based on differences in plumage, geographic range, and song. Previous studies have shown that ecological factors, such as urbanization and climate, can affect learned vocalizations, particularly frequency-related song characteristics such as minimum frequency; however, most studies have been conducted on one species in a specific location. The extensive geographic distributions of these towhee species, along with their ample publicly available song-recording data, give us the unique opportunity to assess whether ecological pressures influence song variation. Here, we extract frequency-related song features from 2916 Spotted and Eastern towhee recordings and investigate whether geography and ecology--including recording location (latitude and longitude), tree cover, urbanization (nighttime lights, human population density, and distance to road), climate zones, elevation, and ecoregions--explain patterns in these song frequency variables of this sister-species pair. Our results show that geographic location, particularly longitude, contributes more strongly to the variation of song frequency features than urbanization, environment, and climate, suggesting that culturally transmitted differences in learned song, not ecology or anthropogenic structure, drive this variation. However, there was not a clear pattern of isolation-by-distance despite the geographic patterns that we found in their songs. Further, we did not find strong support for behavioral adaptation to habitat structure, but we did find a weak signal that urbanization was associated with increased frequency in Spotted towhees. Overall, we provide a detailed study on the interactions between ecology and song evolution, and provide new insight into the evolution of birdsong.

evolutionary biology↗

bioRxiv2025

A spatiotemporal analysis of the effect of urbanization on birdsong

Rising population density and human activities have caused an increase in low-frequency ambient noise, which disrupts auditory communication systems, such as birdsong. In oscine songbirds, birdsong is a learned behavior that functions in territory defense, species recognition, and mate attraction. Increased noise levels in urban areas can reduce signal efficacy, which can have negative impacts on fitness. However, many species have persisted in urban settings by singing at less noisy times of day, singing at higher amplitudes, or changing aspects of their song to reduce masking by low-frequency ambient noise. Previous studies have often focused on modern populations of single species in rural and urban settings; here, we conduct a spatiotemporal analysis of the effects of urbanization on the birdsongs of nine species across [~]60 years. We use machine learning to assess distinguishability between songs from historic and modern timepoints. Additionally, we assess whether variation within modern songs is associated with urbanization, and whether song differences over time are associated with changes in urbanization levels. We find that while there are some song-feature differences between historic and modern songs, and between modern songs along a rural-urban gradient, these differences are not consistent across species. These results reinforce the notion that species respond differently to urbanization by altering different aspects of their songs. For the vocal-learning songbird species studied, historic and modern songs were not distinguishable using dimensionality reduction techniques and machine learning, and some modern songs differed in more urban settings. However, the non-vocal-learning (suboscine) species showed an overall increase in its lower song frequencies in modern songs, but showed no systematic differences in song features along an urbanization gradient, suggesting more dynamic changes in the vocal learners and population-level changes in the non-learners. This spatiotemporal study is the first to compile and analyze historic and modern songs from multiple species alongside urbanization data, bringing new insights to the effects of urbanization on birdsong.

evolutionary biology↗

bioRxiv2024

Cooperative breeding in songbirds promotes female song but slows the evolution of song elaboration

Birdsong has historically been characterized as a sexually selected, primarily male behavior. More recent findings suggest female song is widespread, raising questions about how social functions of birdsong shape song evolution. Certain breeding systems, like cooperative breeding, change social dynamics and selection pressures on both sexes, providing important contexts for studying song evolution. Here, we use phylogenetic comparative analyses across 1041 songbird species to examine relationships between cooperative breeding, female song, and male song characteristics. Here, we show robust bidirectional co-evolutionary dynamics between cooperative breeding and female song that persist when controlling for territoriality, allometry, and geographic sampling biases. Importantly, when examining intensity of territorial defense, we find this relationship is context-dependent: while cooperative breeding and female song commonly co-occur in strongly territorial systems, their association is especially pronounced in weakly territorial systems, where they co-occur much more often than expected by chance. Additionally, we observe that male song repertoire size evolves more slowly in cooperative-breeding lineages. These findings demonstrate that cooperative breeding shapes the evolution of vocal communication differently based on territorial context and sex, with female song potentially serving crucial but understudied functions related to social cohesion in cooperative systems, particularly in species where territorial conflict is reduced.

animal behavior and cognition↗

bioRxiv2023

Song distinguishability predicts reproductive isolation between subspecies of the dark-eyed junco

The dark-eyed junco (Junco hyemalis) has experienced rapid phenotypic diversification within the last 18,000 years, resulting in several subspecies that reside in partially overlapping regions across North America. These subspecies have distinct plumage and morphology. If members of a subspecies disproportionately mate with one another, we would expect genetic differences to accumulate between the subspecies. In parallel, their learned songs could also accumulate changes. If song is used by individuals to recognize members of their own subspecies during mate selection, which would prevent the production of less fit hybrid offspring between subspecies, then song differences might co-localize with subspecies boundaries. Here, we quantify 10 song features to explore subspecies-level song variation using song recordings from community-science databases. We build a machine learning classifier to measure how accurately the subspecies songs can be distinguished from one another. Here, we show that songs of dark-eyed junco subspecies exhibit significant song-feature differences. However, these differences do not necessarily lead to distinguishability between subspecies. Notably, we find that subspecies pairs with adjacent ranges that do not hybridize have much more distinguishable songs, and also more evidence for genetic differentiation, than pairs that are known to hybridize. Thus, song distinguishability appears to have predictive power about which subspecies will hybridize, suggesting that song might play a role in reinforcing certain subspecies boundaries more than others. Finally, we analyze subspecies-level song differences alongside available genetic data and geographic coordinates to characterize the current evolutionary landscape of the dark-eyed junco subspecies complex. We observe geographic signal in the song and genetic data, indicating that individuals who share a range are more likely to share song characteristics and be genetically similar. This study illuminates the existence of subspecies-level song differences in the dark-eyed junco and provides further clarity on the role learned song plays in reinforcing reproductive boundaries between dark-eyed junco subspecies.

evolutionary biology↗

bioRxiv2023

The role of learned song in the evolution and speciation of Eastern and Spotted towhees

Oscine songbirds learn vocalizations that function in mate attraction and territory defense. Sexual selection pressures on these learned songs could accelerate speciation. The Eastern and Spotted towhees are sister species that diverged recently (0.28 Ma) but now have partially overlapping ranges with evidence of some hybridization; widespread community-science recordings of these species, including songs within their zone of overlap and from potential hybrids, enable us to investigate whether song differentiation might facilitate their reproductive isolation. Here, we quantify 16 song features to analyze geographic variation in Spotted and Eastern towhee songs and test for species-level differences. We then use random-forest models to measure how accurately their songs can be classified by species, both within and outside the zone of overlap. While no single song feature reliably distinguishes the two species, a random-forest model trained on 16 features accurately classified 89.5% of songs; interestingly, species classification was less accurate in the zone of overlap. Finally, our analysis of the limited publicly available genetic data from each species supports the hypothesis that they are reproductively isolated. Together, our results suggest that, in combination, small variations in song features may contribute to these sister species ability to recognize their species-specific songs.

evolutionary biology↗

bioRxiv2023

Detecting cultural evolution in a songbird species using community-science data and computational modeling

Song in oscine birds is learned across generations, and aspects of the song-learning process parallel genetic transmission: variation can be introduced into both cultural and genetic traits via copy-error, and both types of traits are subject to drift and selective pressure. Similarly to allele frequencies in population genetics, observing frequencies of birdsong features can improve our understanding of cultural transmission and evolution. Uniquely, community-science databases of birdsong provide rich spatiotemporal data with untapped potential to evaluate cultural evolution in songbirds. Here we use both community-science and field-study recordings of chipping sparrows to examine trends across nearly seven decades of song. We find that some syllable types tend to persist in the population for much longer than others. Persistent songs tend to contain more syllables of shorter duration than songs that were observed across fewer years. To draw inferences about the effects of learning biases on chipping sparrow syllables, we construct a spatially explicit agent-based model of song learning. By comparing our empirical analysis to simulated song distributions using three different song-learning strategies--neutral transmission, conformity bias, and directional selection--we suggest that chipping sparrows are unlikely to select tutors neutrally or with a conformity bias and that they learn their songs with a remarkably low copy-error rate.

evolutionary biology↗

bioRxiv2022

Cultural signatures of punctuated environmental change: measuring the effects of population-wide stress on song distribution in dark-eyed juncos and song sparrows

Severe weather events can dramatically alter a species evolutionary trajectory. Previous landmark studies on populations in transiently hostile environments have measured traits that are under direct selection during those events. However, phenotype shifts that are not inherently adaptive to the fluctuating environment may also occur. Stress, especially during development, can cause important phenotypic changes in individuals, including impaired learning. Thus, learned behaviors, such as birdsong, may exhibit unique evolutionary dynamics as a result of widespread environmental stress. We hypothesize that ecosystem-level stressors may cause population-level changes to birdsong as entire cohorts experience developmental stress, learn songs imperfectly, and become the song tutors for future generations. In 2016, an unprecedented drought affected western New York State, a hotspot for community-science-generated birdsong recordings, and presented a unique opportunity to test our hypothesis through a natural experiment. We analyzed publicly available community-science birdsong recordings of two species, Junco hyemalis and Melospiza melodia, recorded between 2006-2020 in the drought-affected region and two control regions. We found that population-level song features had changed in the species with more complex songs (song sparrow) in the drought area after 2016, but not in the control area or in the species with a simple song (dark-eyed junco), implying that stress-induced deficits may disproportionately affect song traits that are more difficult to learn. These results demonstrate that environmental events can drive population-level trait evolution due to disruption in learning, with potentially important implications for speciation.

evolutionary biology↗

bioRxiv2022

Subtle cultural boundaries reinforce genetic structure in England

Genes and languages both contain signatures of human history. Genetics and culture have each been shown to track population movements and demographic history. Complicating this picture, cultural traits may themselves influence the ways in which people interact with one another. For example, cultural differences can produce barriers to gene flow if they cause groups of people to differentiate themselves from one another. However, the degree of cultural difference necessary and the magnitude of these effects on gene flow remain unknown. In particular, language differences may limit population mixing, and we focus on whether subtle, dialect-level linguistic differences have influenced genetic population structure, likely by affecting mating preferences. Here, we analyze spatially dense linguistic and genetic data to examine whether the intensity of differences between and within dialects in England are associated with high genetic rates of change. We find that genetic variation and dialect markers have similar spatial distributions on a country-wide scale, and become less distinct as the scale of smaller administrative units such as counties. This covariation, combined with the absence of geographic barriers that could coordinate cultural and genetic differentiation, suggests that some dialect-level linguistic boundaries have influenced the genetic population structure in England.

evolutionary biology↗

bioRxiv2022

Modeling effects of inter-group contact on links between population size and cultural complexity

Human populations rely on cultural artifacts and complex cumulative culture for their survival. Populations vary dramatically in the size of their tool repertoires, and the determinants of these cultural repertoire sizes have been the focus of extensive study in recent years. A prominent hypothesis, supported by computational models of cultural evolution, asserts that tool repertoire size increases with population size. However, not all empirical studies seeking to test this hypothesis have found such a correlation; this has led to a contentious and ongoing debate. As a possible resolution to this longstanding controversy, we suggest that accounting for even rare cultural migration events that allow sharing of knowledge between different-sized populations may help explain why a populations size might not always predict its cultural repertoire size. Using an agent-based model to explore different assumptions about the effects of population size and migration on tool repertoires, we find that connectivity of one population to others, particularly to large populations, may significantly boost its tool repertoire size when population interactions lead to cultural exchange. Thus, two populations of identical size may have drastically different tool repertoire sizes, hinging upon their access to other groups knowledge. Intermittent contact between populations boosts cultural repertoire size and still allows for the development of unique tool repertoires that have limited overlap between populations.

evolutionary biology↗

bioRxiv2022

Cultural specialization as a double-edged sword: division into specialized guilds might promote cultural complexity at the cost of higher susceptibility to cultural loss

The transition to specialization of knowledge within populations could have facilitated the accumulation of cultural complexity in humans. Specialization allows populations to increase their cultural repertoire without requiring that members of that population increase their individual capacity to accumulate knowledge. However, specialization also means that domain-specific knowledge can be concentrated in small subsets of the population, making it more susceptible to loss. Here we use a model of cultural evolution to demonstrate that specialized populations can be more sensitive to stochastic loss of knowledge than populations without subdivision of knowledge, and that demographic and environmental changes have an amplified effect on populations with knowledge specialization. Finally, we suggest that specialization can be a double-edged sword; specialized populations may have an advantage in accumulating cultural traits but may also be less likely to expand and establish themselves successfully in new demes due to the increased cultural loss that they experience during the population bottlenecks that often characterize such expansions.

evolutionary biology↗

bioRxiv2021

Genetic structure correlates with ethnolinguistic diversity in eastern and southern Africa

African populations are the most diverse in the world yet are sorely underrepresented in medical genetics research. Here, we examine the structure of African populations using genetic and comprehensive multigenerational ethnolinguistic data from the Neuropsychiatric Genetics of African Populations-Psychosis study (NeuroGAP-Psychosis) consisting of 900 individuals from Ethiopia, Kenya, South Africa, and Uganda. We find that self-reported language classifications meaningfully tag underlying genetic variation that would be missed with consideration of geography alone, highlighting the importance of culture in shaping genetic diversity. Leveraging our uniquely rich multi-generational ethnolinguistic metadata, we track language transmission through the pedigree, observing the disappearance of several languages in our cohort as well as notable shifts in frequency over three generations. We find suggestive evidence for the rate of language transmission in matrilineal groups having been higher than that for patrilineal ones. We highlight both the diversity of variation within the African continent, as well as how within-Africa variation can be informative for broader variant interpretation; many variants appearing rare elsewhere are common in parts of Africa. The work presented here improves the understanding of the spectrum of genetic variation in African populations and highlights the enormous and complex genetic and ethnolinguistic diversity within Africa.

genomics↗

bioRxiv2021

Ornament, armament, or toolkit? Modelling how population size drives the evolution of birdsong, a functional cultural trait

Oscine songbirds have been an important study system for social learning, particularly because their learned songs provide an analog for human languages and music. Here we propose a different analogy; from an evolutionary perspective, could a birds song be more like an arrowhead than an aria? We modify a model of human tool evolution to accommodate cultural evolution of birdsong: each song learner chooses the most skilled available tutor to emulate, and each is more likely to produce an inferior copy than a superior one. Similarly to human tool evolution, we show that larger populations foster improvements in song over time, even when learners restrict their pool of tutors to a subset of individuals. We also demonstrate that songs could be simplified instead of lost after population bottlenecks if lower-quality traits are easier to imitate than higher-quality ones. We show that these processes could plausibly generate empirically observed patterns of song evolution, and we make predictions about the types of song elements most likely to be lost when populations shrink. More broadly, we aim to connect the modeling approaches used in human and non-human systems, moving toward a cohesive theoretical framework that accounts for both cognitive and demographic processes.

animal behavior and cognition↗

bioRxiv2019

Unravelling the genetic architecture of musical rhythm

Moving in synchrony to the beat is a fundamental component of musicality. Here, we conducted a genome-wide association study (GWAS) to identify common genetic variants associated with beat synchronization in 606,825 individuals. Beat synchronization exhibited a highly polygenic architecture, with sixty-nine loci reaching genome-wide significance (p<5x10-8) and SNP-based heritability (on the liability scale) of 13%-16%. Heritability was enriched for genes expressed in brain tissues, and for fetal and adult brain-specific gene regulatory elements, underscoring the role of central nervous system-expressed genes linked to the genetic basis of the trait. We performed validations of the self-report phenotype (through internet-based experiments) and of the GWAS (polygenic scores for beat synchronization were associated with patients algorithmically classified as musicians in medical records of a separate biobank). Genetic correlations with breathing function, motor function, processing speed, and chronotype suggest shared genetic architecture with beat synchronization and provide avenues for new phenotypic and genetic explorations.

genetics↗

bioRxiv2019

Chipper: Open-source software for semi-automated segmentation and analysis of birdsong and other natural sounds

O_LIAudio recording devices have changed significantly over the last 50 years, making large datasets of recordings of natural sounds, such as birdsong, easier to obtain. This increase in digital recordings necessitates an increase in high-throughput methods of analysis for researchers. Specifically, there is a need in the community for open-source methods that are tailored to recordings of varying qualities and from multiple species collected in nature.\nC_LIO_LIWe developed Chipper, a Python-based software to semi-automate both the segmentation of acoustic signals and the subsequent analysis of their frequencies and durations. For avian recordings, we provide widgets to best determine appropriate thresholds for noise and syllable similarity, which aid in calculating note measurements and determining syntax. In addition, we generated a set of synthetic songs with various levels of background noise to test Chippers accuracy, repeatability, and reproducibility.\nC_LIO_LIChipper provides an effective way to quickly generate reproducible estimates of birdsong features. The cross-platform graphical user interface allows the user to adjust parameters and visualize the resulting spectrogram and signal segmentation, providing a simplified method for analyzing field recordings.\nC_LIO_LIChipper streamlines the processing of audio recordings with multiple user-friendly tools and is optimized for multiple species and varying recording qualities. Ultimately, Chipper supports the use of citizen-science data and increases the feasibility of large-scale multi-species birdsong studies.\nC_LI

animal behavior and cognition↗

bioRxiv2019

The role of early acoustic experience in song discrimination

Oscine songbirds are an ideal system for investigating how early experience affects behavior. Young songbirds face a challenging task: how to recognize and selectively learn only their own species song, often during a time-limited window. Because birds are capable of hearing birdsong very early in life, early exposure to song could plausibly affect recognition of appropriate models; however, this idea conflicts with the traditional view that song learning occurs only after a bird leaves the nest. Thus, it remains unknown whether natural variation in acoustic exposure prior to song learning affects the template for recognition. In a population where sister species, golden-crowned and white-crowned sparrows, breed syntopically, we found that nestlings discriminate between heterospecific and conspecific song playbacks prior to the onset of song memorization. We then asked whether natural exposure to more frequent or louder heterospecific song explained any variation in golden-crowned nestling response to heterospecific song playbacks. We characterized the amount of each species song audible in golden-crowned sparrow nests and showed that even in a relatively small area, the ratio of heterospecific to conspecific song exposure varies widely. However, although many songbirds hear and respond to acoustic signals before fledging, golden-crowned sparrow nestlings that heard different amounts of heterospecific song did not behave differently in response to heterospecific playbacks. This study provides the first evidence that song discrimination at the onset of song learning is robust to the presence of closely related heterospecifics in nature, which may be an important adaptation in sympatry between potentially interbreeding taxa.

animal behavior and cognition↗

bioRxiv2018

The evolutionary advantage of cultural memory on heterogeneous contact networks

Cultural processes, as well as the selection pressures experienced by individuals in a population over time and space, are fundamentally stochastic. Phenotypic variability, together with imperfect phenotypic transmission between parents and offspring, has been previously shown to play an important role in evolutionary rescue and (epi)genetic adaptation of populations to fluctuating temporal environmental pressures. This type of evolutionary bet-hedging does not confer a direct benefit to a single individual, but instead increases the adaptability of the whole lineage.\n\nHere we develop a population-genetic model to explore cultural response strategies to temporally changing selection, as well as the role of local population structure, as exemplified by heterogeneity in the contact network between individuals, in shaping evolutionary dynamics. We use this model to study the evolutionary advantage of cultural bet-hedging, modeling the evolution of a variable cultural trait starting from one copy in a population of individuals with a fixed cultural strategy. We find that the probability of fixation of a cultural bet-hedger is a non-monotonic function of the probability of cultural memory between generations. Moreover, this probability increases for networks of higher mean degree but decreases with increasing heterogeneity of the contact network, tilting the balance of forces towards drift and against selection.\n\nThese results shed light on the interplay of temporal and spatial stochasticity in shaping cultural evolutionary dynamics and suggest that partly-heritable cultural phenotypic variability may constitute an important evolutionary bet-hedging strategy in response to changing selection pressures.

evolutionary biology↗