Biology subjects

Anaya-Rojas, J. M.

Publications and source records attributed to Anaya-Rojas, J. M..

3 recordsLinked to original sources

bioRxiv2024

Experimental evolution of a pathogen confronted with innate immune memory increases variation in virulence

Understanding the drivers and mechanisms of virulence evolution is still a major goal of evolutionary biologists and epidemiologists. Theory predicts that the way virulence evolves depends on the balance between the benefits and costs it provides to pathogen fitness. Additionally, host responses to infections, such as resistance or tolerance, play a critical role in shaping virulence evolution. But, while the evolution of pathogens has been traditionally studied under the selection pressure of host adaptive immunity, less is known about their evolution when confronted to simpler and less effective forms of immunity such as immune priming. In this study, we used a well-established insect model for immune priming - red flour beetles and their bacterial pathogen Bacillus thuringiensis tenebrionis - to test whether this form of innate immune memory favors the evolution of higher virulence. Through controlled experimental evolution of the pathogen in primed versus non-primed hosts, we found no change in average virulence after eight selection cycles in primed host. However, we found a significant increase in the variation of virulence (i.e., host-killing ability) among independent pathogen lines evolved in primed host, and bacteria were unable to evolve resistance against host priming. Whole genome sequencing revealed increased activity in the bacterial mobilome (prophages and plasmids). Expression of the Cry toxin - a well-known virulence factor - was linked to evolved differences in copy number variation of the cry-carrying plasmid, though this did not correlate directly with virulence. These findings highlight that innate immune memory can drive variability in pathogen traits, which may favor adaptation to variable environments. This underscores the need to consider pathogen evolution in response to innate immune memory when applying these mechanisms in medicine, aquaculture, pest control, and insect mass production.

evolutionary biology↗

bioRxiv2024

Tapeworm infection affects sleep behavior in three-spined stickleback

Sleep is a highly complex and conserved biological process that affects several body functions and behaviors. Recent evidence suggests that there is a reciprocal interaction between sleep and immunity. For instance, fragmented sleep can increase the probability of parasitic infections and reduce the ability of infected hosts to fight infections. It is also known, particularly in humans and other mammals, that viral and bacterial infections alter the sleep patterns of infected individuals. However, the effects of macro-parasitic infections on sleep remain largely unknown. In this study, we investigated whether macro-parasite infections could alter the sleep of their hosts. We experimentally infected three-spined sticklebacks (Gasterosteus aculeatus) with the tapeworm Schistocephalus solidus and used a hidden Markov model to characterize sleep-associated behaviors in the sticklebacks. At an early time-point, 1-4 days after parasite exposure, infected fish showed no difference in sleep compared with non-exposed fish, whereas fish that were exposed but could fend off the infection slept less during the daytime. At a later time-point, 29-32 days after exposure, infected fish slept more than uninfected fish, while exposed-but-not-infected fish slept less than non-exposed fish. Using RNA-seq of brain tissue, we identified several immune- and sleep-associated genes that potentially underlie the observed behavioral changes. These results provide the first insight into the complex association between macro-parasite infection, immunity, and sleep in fish and may thus contribute to a better understanding of the reciprocal interaction between sleep and immunity.

animal behavior and cognition↗

bioRxiv2021

The evolution of size-dependent competitive interactions promotes species coexistence

O_LITheory indicates that competing species coexist in a community when intraspecific competition is stronger than interspecific competition. When body size determines the outcome of competitive interactions between individuals, coexistence depends also on how resource use and the ability to compete for these resources change with body size. Testing coexistence theory in size-structured communities, therefore, requires disentangling the effects of size-dependent competitive abilities and niche shifts. C_LIO_LIHere, we tested the hypothesis that the evolution of species and size-dependent competitive asymmetries increased the likelihood of coexistence between interacting species. C_LIO_LIWe experimentally estimated the effects of size-dependent competitive interactions on somatic growth rates of two interacting fish species, Trinidadian guppies (Poecilia reticulata) and killifish (Rivulus hartii). We controlled for the effects of size-dependent changes in the niche at two competitive settings representing the early (allopatric) and late (sympatric) evolutionary stages of a killifish-guppy community. We fitted the growth data to a model that incorporates species and size-dependent competitive asymmetries to test whether changes in the competitive interactions across stages increased the likelihood of species coexistence from allopatry to sympatry. C_LIO_LIWe found that guppies are competitively superior to killifish but were less so in sympatric populations. The decrease in the effects of interspecific competition on the fitness of killifish and increase in the interspecific effect on guppies fitness increased the likelihood that sympatric guppies and killifish will coexist. However, while the competitive asymmetries between the species changed consistently between allopatry and sympatry between drainages, the size-dependent competitive asymmetries varied between drainages. C_LIO_LIThese results demonstrate the importance of integrating evolution and trait-based interactions into the research of how species coexistence. C_LI

ecology↗