scholarly journals Could diffuse coevolution explain the generic eggshell color of the brown-headed cowbird?

2021 ◽  
Author(s):  
Daniel Hanley ◽  
Beheshteh Moghaddame-Jafari ◽  
Samantha L Rutledge
Keyword(s):  
Host Species ◽  
Host Community ◽  
Brood Parasite ◽  
Evolutionary Mechanisms ◽  
Selective Pressures ◽  
Reflectance Data ◽  
Insight Into ◽  
Eggshell Color ◽  
Diffuse Coevolution ◽  
Rejection Rates

Abstract The brown-headed cowbird (hereafter cowbird) is an avian brood parasite that produces an egg dissimilar to those produced by the majority of its diverse host community. The cowbird’s generic egg may result from a Jack-of-all-trades strategy; however, the evolutionary mechanisms that select for their generic eggs are unclear. Here we propose that the cowbird’s eggshell phenotypes have evolved via diffuse coevolution, which results from community-level selective pressures, rather than via pairwise coevolution that occurs between a particular host species and its brood parasite. Under diffuse coevolution the cowbird’s host community, with varying eggshell phenotypes and recognition abilities, would select for a cowbird eggshell phenotype intermediate to those of its host community. This selection is exerted by hosts that reject cowbird eggs, rather than those that accept them; therefore, we expect cowbird eggshell colors can be approximated by both the phenotypes and rejection abilities of their host community. Here we use eggshell reflectance data from 43 host species to demonstrate that the cowbird eggshell phenotypes are reasonably predicted (within 2 just noticeable differences) by the eggshell phenotypes and rejection rates of their hosts. These findings suggest that cowbird eggshell phenotypes, and potentially those of other some generalist parasites, may evolve via diffuse coevolution. Importantly, this research provides insight into the underlying evolutionary processes that explain observed phenotypic variation and provides a framework for studying selection on both specialist and generalist parasites' traits.

Costs associated with recognition and rejection of parasitic eggs in two European passerines

Behaviour ◽  
2002 ◽  
Vol 139 (5) ◽  
pp. 629-644 ◽  
Author(s):  
Bård Stokke ◽  
◽  
◽  
◽  
Keyword(s):  
Rejection Rate ◽  
Brood Parasite ◽  
Selective Pressures ◽  
Mixed Support ◽  
The Common ◽  
High Rejection Rate ◽  
Recognition Errors ◽  
High Rejection ◽  
Rejection Rates

AbstractMany avian brood parasite hosts accept parasitic eggs even though successful parasitism frequently is detrimental to their own reproduction. Such behaviour seems suboptimal, but has been explained by the existence of opposing selective pressures operating against the evolution of appropriate host defence. Costs associated with rejection and recognition of eggs are central topics in this respect. Here, we report the occurrence of such costs in two European passerines (chaffinches and blackcaps) that are good rejecters of foreign eggs, even though the common cuckoo does not presently use them as hosts. Since high rejection rates are maintained in the absence of parasitism, we predicted that few recognition errors are made by these species. We tested this prediction by monitoring the occurrence of such errors in both experimentally parasitised and non-parasitised host clutches. We found support for the prediction, as our results show that recognition errors are at best rare events in these two species. We discuss the role of intraspecific brood parasitism as well as other explanations for the retention of a high rejection rate in these species. Various studies have reported mixed support for the occurrence of recognition errors among cuckoo hosts, and we consider other explanations for the existence of both acceptors and rejecters of foreign eggs in host populations.

scholarly journals Links between mouse and vole social networks and their gut microbiomes support predictions from metacommunity theory

2020 ◽  
Author(s):  
Joël W. Jameson ◽  
Steven W. Kembel ◽  
Denis Réale
Keyword(s):  
Social Networks ◽  
Host Species ◽  
Community Dynamics ◽  
Peromyscus Maniculatus ◽  
Interspecific Interactions ◽  
Host Community ◽  
Social Proximity ◽  
Strongly Connected ◽  
Bacterial Transmission

ABSTRACTMetacommunity theory predicts that strongly connected individuals will harbour similar gut microbiomes (GMs) and affiliating with more individuals should increase GM diversity. Additionally, cross-species bacterial transmission may play a role in how interspecific interactions affect host community dynamics. We tracked sympatric mice (Peromyscus maniculatus) and voles (Myodes gapperi) and constructed social networks for each species and both species together. We tested whether: 1) similarity in GM composition between individuals correlates with their social proximity within and across species; 2) GM diversity correlates with a host’s number of conspecific or heterospecific neighbours. We could not differentiate associations between GM composition and mouse social proximity or habitat. In voles, social proximity explained part of the GM composition. GM composition associated with interspecific social proximity, and mouse GM diversity correlated with number of vole neighbours. Contributions of host-host bacterial transmission to the GM partly follow metacommunity theory but depend on host species.

Environmentally driven escalation of host egg rejection decimates success of an avian brood parasite

2020 ◽  
Vol 31 (6) ◽  
pp. 1316-1325 ◽  
Author(s):  
John M Eadie ◽  
Bruce E Lyon
Keyword(s):  
Large Scale ◽  
Ecological Factors ◽  
Water Levels ◽  
Environmental Drivers ◽  
Egg Rejection ◽  
Vital Rates ◽  
Brood Parasite ◽  
Parasitic Lifestyle ◽  
Almost All ◽  
Rejection Rates

Abstract The black-headed duck (Heteronetta atricapilla) of South America is the only known avian obligate brood parasite with precocial offspring. In Argentina, it relies on two species of coots as primary hosts, which typically reject 35–65% of duck eggs. We show that environmentally driven increases in host egg rejection behavior lead to substantial reductions in the reproductive success of the brood parasite. Episodes of flooding and vegetation loss caused dramatic shifts in host egg-rejection behavior, resulting in rejection (85–95%) of almost all duck eggs. Coots respond to fluctuating water levels by building up their nest, raising their own eggs but leaving duck eggs behind. Coots can apparently recognize parasitic duck eggs, but large-scale rejection is triggered only when hosts must actively make a choice. We use a simple population model to illustrate the unique demographic challenges that black-headed ducks face with their parasitic lifestyle and to explore the potential impact of environmentally induced escalation of egg rejection. Using the best available estimates for key vital rates, we show that obligate parasitism may provide a demographically precarious existence for black-headed ducks, even under benign environmental conditions. Environmentally mediated increases in egg rejection rates by hosts could impact significantly the viability of this enigmatic species of brood parasitic duck. Our results demonstrate that egg rejection rates are not fixed properties of host populations or individuals but are strongly influenced by social and ecological factors. Shifts in these environmental drivers could have important and unforeseen demographic consequences for brood parasites.

scholarly journals Experimental Evolution In Vivo To Identify Selective Pressures during Pneumococcal Colonization

mSystems ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Vaughn S. Cooper ◽  
Erin Honsa ◽  
Hannah Rowe ◽  
Christopher Deitrick ◽  
Amy R. Iverson ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Murine Model ◽  
Experimental Evolution ◽  
Nasal Colonization ◽  
Content Type ◽  
Selective Pressures ◽  
Specific Tissue ◽  
Tissue Tropisms ◽  
Insight Into

ABSTRACT Experimental evolution is a powerful technique to understand how populations evolve from selective pressures imparted by the surrounding environment. With the advancement of whole-population genomic sequencing, it is possible to identify and track multiple contending genotypes associated with adaptations to specific selective pressures. This approach has been used repeatedly with model species in vitro, but only rarely in vivo. Herein we report results of replicate experimentally evolved populations of Streptococcus pneumoniae propagated by repeated murine nasal colonization with the aim of identifying gene products under strong selection as well as the population genetic dynamics of infection cycles. Frameshift mutations in one gene, dltB, responsible for incorporation of d-alanine into teichoic acids on the bacterial surface, evolved repeatedly and swept to high frequency. Targeted deletions of dltB produced a fitness advantage during initial nasal colonization coupled with a corresponding fitness disadvantage in the lungs during pulmonary infection. The underlying mechanism behind the fitness trade-off between these two niches was found to be enhanced adherence to respiratory cells balanced by increased sensitivity to host-derived antimicrobial peptides, a finding recapitulated in the murine model. Additional mutations that are predicted to affect trace metal transport, central metabolism, and regulation of biofilm production and competence were also selected. These data indicate that experimental evolution can be applied to murine models of pathogenesis to gain insight into organism-specific tissue tropisms. IMPORTANCE Evolution is a powerful force that can be experimentally harnessed to gain insight into how populations evolve in response to selective pressures. Herein we tested the applicability of experimental evolutionary approaches to gain insight into how the major human pathogen Streptococcus pneumoniae responds to repeated colonization events using a murine model. These studies revealed the population dynamics of repeated colonization events and demonstrated that in vivo experimental evolution resulted in highly reproducible trajectories that reflect the environmental niche encountered during nasal colonization. Mutations impacting the surface charge of the bacteria were repeatedly selected during colonization and provided a fitness benefit in this niche that was counterbalanced by a corresponding fitness defect during lung infection. These data indicate that experimental evolution can be applied to models of pathogenesis to gain insight into organism-specific tissue tropisms.

scholarly journals Community disassembly and disease: realistic—but not randomized—biodiversity losses enhance parasite transmission

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190260 ◽  
Author(s):  
Pieter T. J. Johnson ◽  
Dana M. Calhoun ◽  
Tawni Riepe ◽  
Travis McDevitt-Galles ◽  
Janet Koprivnikar
Keyword(s):  
Species Composition ◽  
Host Species ◽  
Host Community ◽  
Trematode Species ◽  
Parasite Transmission ◽  
Field Surveys ◽  
Larval Amphibians ◽  
Experimental Approaches ◽  
The Individual ◽  
The Relationship

Debates over the relationship between biodiversity and disease dynamics underscore the need for a more mechanistic understanding of how changes in host community composition influence parasite transmission. Focusing on interactions between larval amphibians and trematode parasites, we experimentally contrasted the effects of host richness and species composition to identify the individual and joint contributions of both parameters on the infection levels of three trematode species. By combining experimental approaches with field surveys from 147 ponds, we further evaluated how richness effects differed between randomized and realistic patterns of species loss (i.e. community disassembly). Our results indicated that community-level changes in infection levels were owing to host species composition, rather than richness. However, when composition patterns mirrored empirical observations along a natural assembly gradient, each added host species reduced infection success by 12–55%. No such effects occurred when assemblages were randomized. Mechanistically, these patterns were due to non-random host species assembly/disassembly: while highly competent species predominated in low diversity systems, less susceptible hosts became progressively more common as richness increased. These findings highlight the potential for combining information on host traits and assembly patterns to forecast diversity-mediated changes in multi-host disease systems.

scholarly journals Experimental Evolution in vivo to Identify Selective Pressures During Pneumococcal Colonization

2020 ◽  
Author(s):  
Vaughn S. Cooper ◽  
Erin Honsa ◽  
Hannah Rowe ◽  
Christopher Deitrick ◽  
Amy R. Iverson ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Murine Model ◽  
Experimental Evolution ◽  
Nasal Colonization ◽  
Environmental Niche ◽  
Selective Pressures ◽  
Specific Tissue ◽  
Tissue Tropisms ◽  
Insight Into

AbstractExperimental evolution is a powerful technique to understand how populations evolve from selective pressures imparted by the surrounding environment. With the advancement of whole-population genomic sequencing it is possible to identify and track multiple contending genotypes associated with adaptations to specific selective pressures. This approach has been used repeatedly with model species in vitro, but only rarely in vivo. Herein we report results of replicate experimentally evolved populations of Streptococcus pneumoniae propagated by repeated murine nasal colonization with the aim of identifying gene products under strong selection as well as the population-genetic dynamics of infection cycles. Frameshift mutations in one gene, dltB, responsible for incorporation of D-alanine into teichoic acids on the bacterial surface, evolved repeatedly and swept to high frequency. Targeted deletions of dltB produced a fitness advantage during initial nasal colonization coupled with a corresponding fitness disadvantage in the lungs during pulmonary infection. The underlying mechanism behind the fitness tradeoff between these two niches was found to be enhanced adherence to respiratory cells balanced by increased sensitivity to host-derived antimicrobial peptides, a finding recapitulated in the murine model. Additional mutations were also selected that are predicted to affect trace metal transport, central metabolism and regulation of biofilm production and competence. These data indicate that experimental evolution can be applied to murine models of pathogenesis to gain insight into organism-specific tissue tropisms.ImportanceEvolution is a powerful force that can be experimentally harnessed to gain insight into how populations evolve in response to selective pressures. Herein we tested the applicability of experimental evolutionary approaches to gain insight into how the major human pathogen Streptococcus pneumoniae responds to repeated colonization events using a murine model. These studies revealed the population dynamics of repeated colonization events and demonstrated that in vivo experimental evolution resulted in highly reproducible trajectories that reflect the environmental niche encountered during nasal colonization. Mutations impacting the surface charge of the bacteria were repeatedly selected during colonization and provided a fitness benefit in this niche that was counterbalanced by a corresponding fitness defect during lung infection. These data indicate that experimental evolution can be applied to models of pathogenesis to gain insight into organism-specific tissue tropisms.

scholarly journals Neutral evolution test of the spike protein of SARS-CoV-2 and its implications in the binding to ACE2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Georgina I. López-Cortés ◽  
Miryam Palacios-Pérez ◽  
Gabriel S. Zamudio ◽  
Hannya F. Veledíaz ◽  
Enrique Ortega ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Neutral Theory ◽  
Purifying Selection ◽  
Spike Protein ◽  
Health Concern ◽  
Neutral Evolution ◽  
Evolutionary Mechanisms ◽  
Theory Of Evolution ◽  
Selective Pressures

AbstractAs the SARS-CoV-2 has spread and the pandemic has dragged on, the virus continued to evolve rapidly resulting in the emergence of new highly transmissible variants that can be of public health concern. The evolutionary mechanisms that drove this rapid diversity are not well understood but neutral evolution should open the first insight. The neutral theory of evolution states that most mutations in the nucleic acid sequences are random and they can be fixed or disappear by purifying selection. Herein, we performed a neutrality test to better understand the selective pressures exerted over SARS-CoV-2 spike protein from homologue proteins of Betacoronavirus, as well as to the spikes from human clinical isolates of the virus. Specifically, Tyr and Asn have higher occurrence rates on the Receptor Binding Domain (RBD) and in the overall sequence of spike proteins of Betacoronavirus, whereas His and Arg have lower occurrence rates. The in vivo evolutionary phenomenon of SARS-CoV-2 shows that Glu, Lys, Phe, and Val have the highest probability of occurrence in the emergent viral particles. Amino acids that have higher occurrence than the expected by the neutral control, are favorable and are fixed in the sequence while the ones that have lower occurrence than expected, influence the stability and/or functionality of the protein. Our results show that most unique mutations either for SARS-CoV-2 or its variants of health concern are under selective pressures, which could be related either to the evasion of the immune system, increasing the virus’ fitness or altering protein – protein interactions with host proteins. We explored the consequences of those selected mutations in the structure and protein – protein interaction with the receptor. Altogether all these forces have shaped the spike protein and the continually evolving variants.

scholarly journals Under the radar: detection avoidance in brood parasitic bees

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180196 ◽  
Author(s):  
Jessica R. Litman
Keyword(s):  
Brood Parasitism ◽  
Solitary Bees ◽  
General Context ◽  
Brood Parasite ◽  
Theme Issue ◽  
Evolutionary Transitions ◽  
Brood Parasites ◽  
Selective Pressures ◽  
Specialized Form ◽  
Fierce Competition

Brood parasitism is a specialized form of parasitism in which the offspring of a parasite develops on the food provisions gathered by a host species for its own young. Obligate brood parasitic lineages have lost the ability to acquire provisions for their young and thus rely entirely on the location of an appropriate host to serve as a food-provider. Solitary bees provide some of the most fascinating examples of brood parasitism in animals. Most solitary bees build and provision their own nests. Some, however, usurp the nests of other species of bees. These brood parasites, or ‘cuckoo’ bees, deposit their eggs on the pollen provisions collected by a host bee for her own offspring. The provisions stored by the host bee are not sufficient to sustain the development of both the host's larva and that of the brood parasite and the parasite must kill the offspring of its host in order to obtain enough nourishment to complete its development. As a consequence, there is fierce competition between the host bee seeking to protect her nest from attack and the brood parasite seeking to avoid detection by the host in order to successfully deposit her eggs in an appropriate nest. In this paper, I review the behaviours that allow brood parasitic bees to escape detection by their hosts. Identifying these behaviours, and placing them within the general context of strategies employed by brood parasitic bees to parasitize the nests of their hosts, is key to understanding how brood parasitic lineages may have evolved from nest-building ancestors, decrypting the selective pressures that drive evolutionary transitions from one strategy to another and, more broadly, revealing how similar selective pressures in widely divergent lineages of animals have given rise to remarkably convergent behaviours. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

Evolution and Physiology of Amphibious Yeasts

2021 ◽  
Vol 75 (1) ◽  
Author(s):  
Fouad El Baidouri ◽  
Polona Zalar ◽  
Timothy Y. James ◽  
Amy S. Gladfelter ◽  
Anthony Amend
Keyword(s):  
Online Publication ◽  
Convergent Evolution ◽  
Annual Review ◽  
Publication Date ◽  
Ecological Diversity ◽  
Aquatic Habitats ◽  
Evolutionary Mechanisms ◽  
Unicellular Organisms ◽  
Extreme Habitats ◽  
Insight Into

Since the emergence of the first fungi some 700 million years ago, unicellular yeast-like forms have emerged multiple times in independent lineages via convergent evolution. While tens to hundreds of millions of years separate the independent evolution of these unicellular organisms, they share remarkable phenotypic and metabolic similarities, and all have streamlined genomes. Yeasts occur in every aquatic environment yet examined. Many species are aquatic; perhaps most are amphibious. How these species have evolved to thrive in aquatic habitats is fundamental to understanding functions and evolutionary mechanisms in this unique group of fungi. Here we review the state of knowledge of the physiological and ecological diversity of amphibious yeasts and their key evolutionary adaptations enabling survival in aquatic habitats. We emphasize some genera previously thought to be exclusively terrestrial. Finally, we discuss the ability of many yeasts to survive in extreme habitats and how this might lend insight into ecological plasticity, including amphibious lifestyles. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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