Biology subjects

Webster, M. S.

Publications and source records attributed to Webster, M. S..

7 recordsLinked to original sources

bioRxiv2025

Use of anthropogenic material for extended ornamented phenotype in two fairy-wrens

Birds often advertise their quality to potential mates through sexual displays that complement their colorful plumage. Some species use materials to enhance their attractiveness, such as the use of colorful fruits and anthropogenic materials in the display bowers across bowerbirds. Here we report the first observations of anthropogenic materials in sexual displays by two fairy-wren species. On two separate occasions and sites, we witnessed a White-winged and Red-backed male carrying a piece of plastic as a substitute for a flower petal during a petal display, which are used across Malurus to enhance reproductive fitness. Given increasing plastic pollution globally, the use of anthropogenic materials as part of extended phenotypes in birds and other animals will likely increase and it will be important to understand the effect this has on populations.

ecology↗

bioRxiv2025

Seeking smarts: Male chickadees with better spatial cognition sire more extra-pair young

Across animal taxa, females commonly mate with more than one male, even in monogamous mating systems. These extra-pair (EP) copulations and resulting young may increase the fitness of the female via a variety of mechanisms. The "good genes" hypothesis suggests that socially monogamous females mate outside their pair bond to increase the fitness of their offspring via indirect genetic benefits, because extra-pair males do not provide parental care. We tested this hypothesis by quantifying extra-pair paternity in nonmigratory, food-caching mountain chickadees (Poecile gambeli). Chickadees rely on spatial cognition to recover scattered food caches and variation in spatial cognition is associated with increased survival, longer lifespan, and is heritable. However, less is known about the role of sexual selection on spatial cognitive abilities. In the current study, we found that 1. males with better spatial cognitive abilities sired more extra-pair young and produce heavier offspring in their own nests compared to their poorer performing counterparts, and 2. extra-pair males had significantly better spatial cognition than the social males they cuckolded. These results suggest that sexual selection shapes the evolution of spatial cognition in food-caching chickadees and are consistent with the good genes hypothesis, which posits that females gain indirect genetic benefits via extra-pair young.

animal behavior and cognition↗

bioRxiv2023

Plural breeding among unrelated females and other insights on complex social structure in the cooperatively breeding Variegated Fairywren

Cooperatively breeding species vary widely in degree of social complexity, and disentangling relationships among group members can reveal the costs and benefits of cooperation. Here, we explore the social system of a relatively unstudied cooperatively breeding bird, the Variegated Fairywren (Malurus lamberti), and explore how social complexity and group dynamics may affect cooperation and conflict. We used a combination of field-based population monitoring and detailed social association observations to determine group membership annually across four breeding seasons (2014 - 2017), and used a ddRAD-seq genotyping method to determine genetic relationships within social groups. Social groups ranged in size from 2 - 8 individuals and nearly half of all social groups had multiple adult individuals of both sexes. Approximately two-thirds of those groups exhibited plural breeding, in which multiple females within the same social group nested individually on the same territory. Genetic relationships were diverse across social groups, and many consisted of a combination of relatives and non-relatives of each sex. Notably, although related females often were present within a social group, co-breeding females in the same social group were never closely related to each other. Given extensive variation in relatedness among group members, cooperation in the Variegated Fairywren is likely maintained by a combination of direct and indirect fitness benefits.

ecology↗

bioRxiv2020

Widlfire affects circulating hormone levels and the expression of male sexual plumage in a tropical songbird

Natural disturbances like drought and wildfires are expected to increase in prevalence, so understanding how organisms are affected is a key goal for conservationists and biologists alike. While many studies have illustrated long-term effects of perturbations on survival and reproduction, little is known of short-term effects to physiology and sexual signal expression. Ornamental traits have been proposed as reliable indicators of environmental health, yet studies are lacking in the context of natural disturbances. Here we present short-term responses of male Red-backed Fairywrens (Malurus melanocephalus) to wildfire near the onset of the typical breeding season. Males of this species are characterized by plastic expression of sexual plumage phenotypes in their first breeding season. Using two populations with Fairywren captures before and after separate wildfires we illustrate that wildfire suppressed molt into ornamented plumage, including in third year males that typically show little plasticity in ornamentation. Baseline plasma corticosterone was elevated in males sampled after fire, but condition (furcular fat stores) was unaffected. Although testosterone levels did not decrease following fire, we found a positive correlation between testosterone and plumage ornamentation. In addition, males molting in ornamental plumage had higher circulating levels of testosterone than males molting in unornamented plumage following fire. Collectively, these findings suggest that wildfires inhibit or greatly delay acquisition of ornamentation in young males without exerting obvious effects on condition, but rather through subtle effects on testosterone and corticosterone circulation. This natural experiment also reveals that expression of alternative male reproductive phenotypes in this species is sensitive to environmental conditions and more plastic than previously assumed.

ecology↗

bioRxiv2020

Variance in within-pair reproductive success drives the opportunity for sexual selection annually and over the lifetimes of males in a multi-brooded songbird

In socially monogamous species, male reproductive success consists of within-pair offspring produced with their socially-paired mate(s), and extra-pair offspring produced with additional females throughout the population. Both reproductive pathways offer distinct opportunities for selection in wild populations, as each is composed of separate components of mate attraction, female fecundity, and paternity allocation. Identifying key sources of variance and covariance among these components is a crucial step towards understanding the reproductive strategies that males use to maximize fitness both annually and over their lifetimes. We use 16 years of complete reproductive data from a population of black-throated blue warblers (Setophaga caerulescens) to partition variance in male annual and lifetime reproductive success, and thereby identify if the opportunity for selection varies over the lifetimes of individual males and what reproductive strategies likely favor maximum lifetime fitness. The majority of variance in male reproduction was attributable to within-pair success, but the specific effects of individual components of variance differed between total annual and total lifetime reproductive success. Positive overall lifetime covariance between within-pair and extra-pair components indicates that males able to maximize within-pair success, particularly with double-brooding females, likely achieve higher overall lifetime fitness via both within-pair and extra-pair reproductive pathways.

evolutionary biology↗

bioRxiv2020

Geometric Analysis of Regime Shifts in Coral Reef Communities

Coral reefs are among the many communities believed to exhibit regime shifts between alternative stable states, single-species dominance, and coexistence. Proposed drivers of regime shifts include changes in grazing, spatial clustering, and ocean temperature. Here we distill the dynamic regimes of coral-macroalgal interaction into a three-dimensional geometry, akin to thermodynamic phase diagrams of state transitions, to facilitate analysis. Specific regime-shifting forces can be understood as bifurcation vectors through the cubic regime geometry. This geometric perspective allows us to understand multiple forces simultaneously in terms of the stability and persistence of interacting species. For example, in a coral-macroalgae community, grazing on macroalgae can lead to alternative stable states when there is no spatial clustering (e.g., high habitat connectivity). However, with spatial clustering, grazing can lead to coexistence because of elevated local intraspecific competition. The geometrical analysis of regime shifts is applicable to any two-species communities and can help conservation efforts navigate complexity and abrupt changes.

ecology↗

bioRxiv2017

Double-digest RAD sequencing outperforms microsatellite loci at assigning paternity and estimating relatedness: a proof of concept in a highly promiscuous bird

Information on genetic relationships among individuals is essential to many studies of the behavior and ecology of wild organisms. Parentage and relatedness assays based on large numbers of SNP loci hold substantial advantages over the microsatellite markers traditionally used for these purposes. We present a double-digest restriction site-associated DNA sequencing (ddRAD-seq) analysis pipeline that, as such, simultaneously achieves the SNP discovery and genotyping steps and which is optimized to return a statistically powerful set of SNP markers (typically 150-600 after stringent filtering) from large numbers of individuals (up to 240 per run). We explore the tradeoffs inherent in this approach through a set of experiments in a species with a complex social system, the variegated fairy-wren (Malurus lamberti), and further validate it in a phylogenetically broad set of other bird species. Through direct comparisons with a parallel dataset from a robust panel of highly variable microsatellite markers, we show that this ddRAD-seq approach results in substantially improved power to discriminate among potential relatives and considerably more precise estimates of relatedness coefficients. The pipeline is designed to be universally applicable to all bird species (and with minor modifications to many other taxa), to be cost- and time-efficient, and to be replicable across independent runs such that genotype data from different study periods can be combined and analyzed as field samples are accumulated.

animal behavior and cognition↗