Biology subjects

Estandia, A.

Publications and source records attributed to Estandia, A..

12 recordsLinked to original sources

bioRxiv2026

Carry-over effects and plasticity to temperature shape phenology across life stages and generations

Climate change is advancing spring phenology in temperate systems, with the potential to disrupt synchrony between trophic levels. Predicting these shifts requires understanding not only direct plastic responses to temperature, but also how plasticity at one stage carries over to shape timing at subsequent stages. We experimentally quantified direct thermal plasticity in phenology and its carry-over effects across the full life cycle of the winter moth (Operophtera brumata), a holometabolous insect whose fitness relies on synchrony with host plant budburst. Using a fully factorial split-clutch rearing experiment across four temperature treatments, we exposed individuals to contrasting conditions at each life stage and used structural equation modelling to partition direct and carry-over effects on phenology. Each life stage showed distinct plastic responses to temperature. Carry-over effects transmitted approximately 0.38 days/day of plastic advance to the next life stage on average, with the remainder absorbed by compensatory changes in the duration of the subsequent life stage. Together, these results show that carry-over effects propagate plastic responses across the life cycle, which are partially buffered by compensatory changes in developmental duration. Accurate predictions of phenological shifts under climate change therefore require models that account for carry-over effects and developmental compensation across life stages.

ecology↗

bioRxiv2026

Recent hybridisation and ghost introgression among a trio of island passerines

Hybridisation between species was once considered a relatively uncommon occurrence but is now recognised to occur frequently across many different taxa. It can result in homogenisation of previously distinct forms, a potential conservation issue, but can also act as a catalyst for diversification through introgression and sharing of favourable genes. Repeated rounds of island colonisation followed by speciation result in secondary sympatry, with the potential for hybridisation between early and late arrivers. In the southwest Pacific, this situation has arisen in the avian family Zosteropidae (the white-eyes). Here we use whole genome sequencing of live birds and historical specimens to characterise hybridisation between three white-eye species on Norfolk Island: two island endemics, Zosterops tenuirostris and the now-extinct Zosterops albogularis, and Zosterops lateralis, which colonised the island in 1904. Despite over two million years of divergence between Z. lateralis and the two endemics, we provide genomic evidence of their hybridisation. First, we confirm the identities of three Z. lateralis x Z. tenuirostris hybrids and additionally identify one Z. lateralis x Z. albogularis hybrid. We also report asymmetric, genome-wide introgression from both endemics into Z. lateralis, with introgressed regions enriched for a range of potential functions. However, despite this introgression, species boundaries have been maintained, and the extant endemic Z. tenuirostris does not appear to be at risk of genetic extinction. Our work additionally demonstrates an unusual case of recent ghost introgression from the extinct Z. albogularis into Z. lateralis. This study sheds light on the genomic outcomes of secondary sympatry and its potential consequences for single-island endemics.

evolutionary biology↗

bioRxiv2026

Transmission strategy modulates parasite biogeography in an island-colonising bird

Parasites occur in every ecosystem, although their dispersal is often constrained by the availability of hosts or vectors. Here, we explore how variation in parasite life history traits, particularly transmission strategy, may influence their distributions. Specifically, we test whether a variety of parasites ad-here to the rules of island biogeography, and whether their distributions vary with transmission strategy. We utilised broad-spectrum parasite detection from existing Whole Genome Sequence (WGS) data to characterise parasites with varying transmission strategies from the blood of a passerine bird, the silvereye (Zosterops lateralis), sampled across 25 islands in the South Pacific and from five of the states in mainland Australia. Overall, parasite richness was higher on mainland Australia compared to islands and decreased with distance of islands from the Australian continent. However, these patterns were dependent on transmission strategy. For parasites transmitted by flying insect vectors, richness decreased on islands compared to the mainland. However, increasing isolation from the mainland among islands had little further impact. On the other hand, richness of directly transmitted parasites and those requiring another intermediate host declined sharply with increasing distance from the mainland. While islands may act as an initial barrier to colonisation for parasites relying on flying insect vectors, their highly dispersive vectors may subsequently reduce the impact of increasing isolation distance on richness. Our work underscores the importance of considering parasite life-histories and their transmission strategies for understanding the processes that shape parasite communities on islands.

ecology↗

bioRxiv2026

Life cycle complexity shapes parasite sharing amongst migratory and resident hosts

Migratory animals are potentially important parasite dispersers. However, understanding the impact of host migration on parasite distributions is challenging because variation in parasite life histories can mediate dispersal potential. Furthermore, studies of parasite dispersal via host migration often compare parasites in different species of migrant and resident hosts, despite differences in host phylogeny, ecology, and exposure history, which can complicate ascertaining the impact of migration. The Tasmanian population of silvereye (Zosterops lateralis lateralis) exhibits partial migration. Some members of the population overwinter on the Australian mainland, where they co-occur with residents of another silvereye subspecies (Z. l. cornwalli). Utilising targeted PCR, metabarcoding and high-throughput sequencing, we characterise a range of parasite genera from blood and faecal samples in Tasmanian resident, migrant and mainland resident birds. Greater parasite richness was documented in migrant individuals, possibly reflecting exposure to varied parasite faunas at stopovers or during overwintering. The increased richness was primarily driven by parasites with simple life cycles. Reduced sharing of parasites with complex life cycles amongst migratory and resident host populations may be explained by ecological constraints in establishing transmission, such as vector or secondary host availability. Our study exemplifies the utility of molecular methods for characterising multi-parasite systems and makes use of a single host species to provide insights on patterns of parasite distributions that result from migratory movements. Knowing how parasite life histories constrain or promote dispersal via regular host migration will be essential for predicting future patterns of pathogen dispersal under climate change and shifting migratory regimes.

ecology↗

bioRxiv2025

Integrative analysis of fine-scale local adaptation of winter moths to variable oak phenology

For herbivorous insects whose fitness depends on tight phenological synchrony with host plants, spatial variation in plant phenology can impose strong selective pressures and promote local adaptation to host timing. These dynamics are central to predicting how species will respond to environmental change, particularly climate-driven shifts in plant phenology. The winter moth (Operophtera brumata) relies on synchronising larval egg hatch with leaf budburst of deciduous trees, yet whether they are locally adapted to their hosts phenology, and their capacity to track future change, remains unclear. Here, we investigated potential small-scale local adaptation of winter moths to oak tree phenology in Wytham Woods, UK, a 385-hectare woodland, within which oak budburst can vary by up to three weeks within a given year. We conducted laboratory temperature manipulation experiments using 76 clutches across six temperature treatments, and field translocation experiments using over 200 clutches. We combined these experiments with assessment of population structure from whole-genome sequencing of 59 individuals. This integrative approach allowed us to assess local adaptation in terms of phenotypic differences, fitness consequences, and genetic evidence. Temperature manipulations revealed systematic differences in the timing of egg hatching across temperature treatments at the clutch level which were linked to carry-over effects from the mothers emergence time, but unrelated to their source tree budburst timing. Field translocation experiments further showed no significant differences in survival of individuals transplanted to trees with phenology differing from their original host tree, and there was no genetic structure across the population. Together, these results reveal consistent differences in hatching phenology despite the absence of population structure, strong selection, or accordance with relative tree phenology. Our findings advance our understanding of the mechanisms maintaining close synchrony in trophic interactions at small scales, which may drive spatial variation in evolutionary responses to future climate change.

evolutionary biology↗

bioRxiv2025

The genetic consequences of dispersal and immigration in a wild great tit population

Understanding how dispersal impacts the genetic makeup of populations is essential for predicting their responses to environmental change. Gene flow--via within-population dispersal and external immigration--shapes population health and evolutionary potential by boosting genetic diversity, but it can also counteract local adaptation. We investigate these processes in a population of great tits (Parus major) in Wytham Woods, United Kingdom. This system represents a large, continuous population of a vagile, widely distributed species. Using a comprehensive social pedigree alongside genomic data from two genomic datasets, one with 949 individuals genotyped at ~600,000 SNPs and another with 2,644 individuals at ~10,000 SNPs, we observe some spatial genetic structure largely driven by the spatial and temporal clustering of close kin. We quantify how temporally persistent this pattern is and find similar levels of decay of relatedness with distance across years, without a consistent genetic basis, which is frequently renewed due to high population turnover. Immigrants make up a substantial portion of the breeding population, yet are often assumed to be genetically distinct, unrelated, and outbred--assumptions that can bias population inferences. We show that immigrants are indeed outbred, as are local birds; have fewer close relatives within the population, and are less likely to be related to their neighbours than locally born birds. Despite low FST and no clear genome-wide population structure, immigrants and locals can be distinguished above chance using a Random Forest classifier trained on SNP data. Our study highlights the complex interplay between dispersal, population turnover and spatial population structure, and suggests that great tits in Wytham Woods experience substantial gene flow within the population and from immigrants, maintaining high genetic diversity and reducing the possibility of local adaptation at this spatial scale.

evolutionary biology↗

bioRxiv2024

Islands promote diversification within the silvereye clade: a phylogenomic analysis of a great speciator

Geographic isolation plays a pivotal role in speciation by restricting gene flow between populations through distance or physical barriers. However, the speciation process is complex, influenced by the interplay between dispersal ability and geographic isolation, especially in "great speciators" - bird species present on multiple islands that, at the same time, have many subspecies. Comparing population differentiation in both continental and insular settings can help us to understand the importance of geographical context in the emergence of great speciators. The highly diverse white-eye family Zosteropidae includes several great speciators, including the silvereye (Zosterops lateralis) which consists of 16 subspecies, 11 occurring on islands. The distribution of the silvereye on the Australian continent and numerous southwest Pacific islands allows us to explore the influence of different forms of geographic isolation on population divergence. To do this, we conducted a comprehensive phylogenomic analysis of the silvereye and compared patterns of population divergence in insular versus continental silvereye populations. We estimate that the silvereye lineage emerged approximately 1.5 million years ago, followed by the split of the two main silvereye clades: Southern Melanesia and the broader South Pacific (encompassing Australia, New Zealand, and outlying islands). Continental populations show low genetic population structure, which suggests that they can overcome multiple forms of geographic barriers across long distances. In contrast, most island populations are highly structured even over relatively short distances. Divergence statistics further support the idea that water barriers lead to a higher population differentiation when compared to continental distances. Our results indicate that islands promote divergence and provide an empirical example of the geographical conditions that result in the emergence of great speciators.

evolutionary biology↗

bioRxiv2023

The demographic drivers of cultural evolution in bird song: a multilevel study

Social learning within communities sometimes leads to behavioural patterns that persist over time, which we know as culture. Examples of culture include learned bird and whale songs, cetacean feeding techniques, and avian and mammalian migratory routes. Shaped by neutral and selective forces, animal cultures evolve dynamically and lead to cultural traditions that differ greatly in their diversity and stability. These cultural traits can influence individual and group survival, population structure, and even inform conservation efforts, underscoring the importance of understanding how other population processes interact with social learning to shape culture. Although the impact of social learning mechanisms and biases has been extensively explored, the role of demographic factors--such as population turnover, immigration, and age structure--on cultural evolution has received theoretical attention but rarely been subject to empirical investigation in natural populations. Doing so requires very complete trait sampling and detailed individual life history data, which are hard to acquire in combination. To this end, we built a multi-generational dataset containing over 109,000 songs from >400 individuals from a population of Great Tits (Parus major), which we study using a deep metric learning model to re-identify individuals and quantify song similarity. We show that demographic variation at the small spatial scales at which learning takes place has the potential to strongly impact the pace and outcome of animal cultural evolution. For example, age distributions skewed towards older individuals are associated with slower cultural change and increased diversity, while higher local population turnover leads to elevated rates of cultural change. Our analyses support theoretical expectations for a key role of demographic processes resulting from individual behaviour in determining cultural evolution, and emphasize that these processes interact with species-specific factors such as the timing of song acquisition. Implications extend to large-scale cultural dynamics and the formation of dialects or traditions.

animal behavior and cognition↗

bioRxiv2023

A densely sampled and richly annotated acoustic dataset from a wild bird population

We present a high-resolution, densely-sampled dataset of wild bird songs collected over multiple years from a single population of Great Tits (Parus major) in the UK. The dataset includes over 1,100,000 individual acoustic units from 109,963 richly annotated songs, sung by more than 400 individual birds, and provides unprecedented detail on the vocal behaviour of wild birds. Here, we describe the data collection and processing procedures and provide a summary of the data. We also discuss potential research questions that can be addressed using this dataset, including behavioural repeatability and stability, links between vocal performance and reproductive success, the timing of song production, syntactic organisation of song production, and song learning in the wild. We have made the dataset and associated software tools publicly available with the aim that other researchers can benefit from this resource and use it to further our understanding of bird vocal behaviour in the wild.

animal behavior and cognition↗

bioRxiv2023

Standing genetic variation and de novo mutations underlie parallel evolution of island bird phenotypes

Parallel evolution occurs when the same trait evolves in closely related lineages in response to similar ecological contexts and provides some of the best examples of determinism in evolutionary biology. However, from a genetic standpoint, this process can be driven by either new mutations that appear independently in each diverging population or by selection on existing genetic variation common to both lineages. Small-bodied birds, for example, tend to increase in size after they colonise a new island, following what is known as the island rule. Such is the case of the silvereye (Zosterops lateralis), a prolific natural coloniser of southwest Pacific islands. Island forms of this bird species increase in body size after they establish, with the pattern and pace of change consistent with directional natural selection and evident even in the most recent colonisations within the last 200 years. The system provides an exceptional opportunity to explore the genomic basis of repeated body size evolution. We sequenced 377 whole genomes from 31 different silvereye populations, which revealed that both mechanisms are at play: in some lineages, new mutations are highly associated with body and bill size, but there are also highly associated polymorphisms present across all populations. Our research sheds light on the genomic basis of repeated body size evolution and emphasises that multiple molecular mechanisms can underlie similar evolutionary trajectories even within a single taxon.

evolutionary biology↗

bioRxiv2023

Candidate gene length polymorphisms are linked to dispersive behaviour: searching for a mechanism behind the "paradox of the great speciators"

The "paradox of the great speciators" has puzzled evolutionary biologists for over half a century. A great speciator requires excellent dispersal ability to explain its occurrence on multiple islands, but reduced dispersal ability to explain its high number of subspecies. A rapid reduction in dispersal ability is often invoked to solve this apparent paradox, but a proximate mechanism has not been identified. Here, we explore the role of six genes linked to migration and animal personality differences (CREB1, CLOCK, ADCYAP1, NPAS2, DRD4, and SERT) in 20 South Pacific populations of silvereye (Zosterops lateralis) that range from highly sedentary to partially migratory, to determine if genetic variation is associated with dispersal propensity. We detected genetic associations in three of the six genes: i) in a partial migrant population, migrant individuals had longer microsatellite alleles at the CLOCK gene compared to resident individuals from the same population; ii) CREB1 displayed longer average microsatellite allele lengths in recently colonised island populations (< 200 years), compared to evolutionarily older populations. Bayesian broken stick regression models supported a reduction in CREB1 length with time since colonisation and decreasing dispersal propensity; and iii) like CREB1, DRD4 showed differences in polymorphisms between recent and old colonisations but a further sample size is needed to confirm. ADCYAP1, SERT, and NPAS2 were variable but that variation was not associated with dispersal propensity. The association of genetic variants at three genes with migration and dispersal ability in silvereyes provides the impetus for further exploration of genetic mechanisms underlying dispersal shifts, and the prospect of resolving a long-running evolutionary paradox through a genetic lens.

evolutionary biology↗

bioRxiv2021

Substitution Rate Variation in a Robust Procellariiform Seabird Phylogeny is not Solely Explained by Body Mass, Flight Efficiency, Population Size or Life History Traits

Substitution rate variation among branches can lead to inaccurate reconstructions of evolutionary relationships and obscure the true phylogeny of affected clades. Body mass is often assumed to have a major influence on substitution rate, though other factors such as population size, life history traits, and flight demands are also thought to have an influence. Birds of the order Procellariiformes--which encompasses petrels, storm-petrels and albatrosses--show a striking 900-fold difference in body mass between the smallest and largest members, divergent life history traits, and substantial heterogeneity in mitochondrial substitution rates. Here, we used genome-scale nuclear DNA sequence data from 4365 ultraconserved element loci (UCEs) in 51 procellariiform species to examine whether phylogenetic reconstruction using genome-wide datasets is robust to the presence of rate heterogeneity, and to identify predictors of substitution rate variation. Our results provide a backbone phylogeny for procellariiform seabirds and resolve several controversies about the evolutionary history of the order, demonstrating that albatrosses are basal, storm-petrels are paraphyletic and diving petrels nestled within the Procellariidae. We find evidence of rate variation; however, all phylogenetic analyses using both concatenation and multispecies coalescent approaches recovered the same branching topology, including analyses implementing different clock models, and analyses of the most and least clock-like loci. Overall, we find that rate heterogeneity is little impacted by body mass, population size, age at first breeding, and longevity but moderately correlated with hand-wing index, a proxy for wing shape and flight efficiency. Given our results and the context of the broader literature perhaps it is time that we begin to question the prevailing paradigm that one or a few traits largely explain rate variation and accept instead that substitution rate may be the product of weak interactions among many, potentially taxon-specific, variables.

evolutionary biology↗