Biology subjects

Morrison, C. R.

Publications and source records attributed to Morrison, C. R..

6 recordsLinked to original sources

bioRxiv2022

Poison frog diet and chemical defense are influenced by availability and selectivity for ants

The ability to use small molecule alkaloids as defensive chemicals, often acquired via trophic interactions, has evolved in many organisms. Animals with diet-derived defenses must balance food choices to maintain their defense reservoirs along with other physiological needs. Poison frogs accumulate skin alkaloids from their arthropod diet, but whether they show preference for specific prey remains unexplored. Here, we explore the role of leaf litter prey availability and diet preferences in shaping poison frog chemical defenses along a geographic gradient. We examined skin alkaloid composition, stomach contents and leaf litter ants in aposematic diablito frogs (Oophaga sylvatica) at five sites in northwestern Ecuador, and in sympatric, cryptic Chimbo rocket frogs (Hyloxalus infraguttatus) at one site. We found that differential availability of leaf litter ants influenced alkaloid profiles across diablito populations, and low levels of alkaloids were observed in the sympatric, undefended Chimbo rocket frog. Ants were the primary dietary component of the defended species, while undefended species ate other prey categories including beetles and larvae in addition to ants. A prey selection analysis suggested that defended and undefended frogs both feed on a high proportion of specific small ant genera that naturally contain alkaloids, suggesting that selectivity for toxic prey is not restricted to classically aposematic and highly toxic species. These findings suggest that poison frogs use of feeding resources relative to availability may be an understudied and important selection factor in the evolution of acquired defenses. ResumenLa capacidad de usar alcaloides como productos quimicos defensivos ha evolucionado en muchos organismos, a menudo a traves de interacciones troficas. Los animales con defensas que se derivan de la dieta deben balancear la seleccion de los alimentos para mantener sus reservas defensivas junto con otras necesidades fisiologicas. Las ranas venenosas acumulan alcaloides en la piel procedentes de su dieta de artropodos, pero aun no se ha explorado si muestran preferencia por presas especificas. En este estudio, investigamos el papel de la disponibilidad de presas en la hojarasca y las preferencias dietarias en la configuracion de las defensas quimicas de las ranas venenosas a lo largo de un gradiente geografico. Examinamos la composicion de alcaloides en la piel, el contenido estomacal y la presencia de hormigas de la hojarasca en ranas aposematicas diablito (Oophaga sylvatica) en cinco sitios del noroeste de Ecuador, asi como en la especie criptica y simpatrica rana cohete de Chimbo (Hyloxalus infraguttatus) en un sitio. Encontramos que la disponibilidad diferencial de hormigas en la hojarasca influyo en los perfiles de alcaloides en las poblaciones de diablito, y se detectaron niveles bajos de alcaloides en la rana cohete de Chimbo, previamente considerada indefensa. Las hormigas fueron el componente principal de la dieta en la especie defendida, mientras que la especie indefensa consumio otras categorias de presas, incluidos escarabajos y larvas, ademas de hormigas. Un analisis de seleccion de presas indico que tanto las ranas defendidas como las indefensas prefieren ciertos generos de hormigas pequenas que contienen alcaloides de forma natural, lo que sugiere que la preferencia por presas toxicas no esta restringida a especies clasicamente aposematicas y altamente toxicas. Estos hallazgos sugieren que las preferencias de comportamiento pueden ser un factor de seleccion poco estudiado, pero crucial, en la evolucion de las defensas adquiridas.

ecology↗

bioRxiv2021

Genetic regulation of homeostatic immune architecture in the lungs of Collaborative Cross mice

Variation in immune homeostasis, immune system stability, in organ systems such as the lungs is likely to shape the host response to infection at these exposed tissues. We evaluated immune homeostasis in immune cell populations in the lungs of the Collaborative Cross (CC) mouse genetic reference population. We found vast heritable variation in leukocyte populations with the frequency of many of these cell types showing distinct patterns relative to classic inbred strains C57BL/6J and BALB/cJ. We identified 28 quantitative trait loci (QTL) associated with variation in baseline lung immune cell populations, including several loci that broadly regulate the abundance of immune populations from distinct developmental lineages, and found that many of these loci have predictive value for influenza disease outcomes, demonstrating that genetic determinants of homeostatic immunity in the lungs regulate susceptibility to virus-induced disease. All told, we highlight the need to assess diverse mouse strains in understanding immune homeostasis and resulting immune responses.

genetics↗

bioRxiv2020

Egg cannibalism by passion vine specialist Disonycha Chevrolat beetles (Coleoptera: Chrysomelidae: Galerucinae: Alticini)

Cannibalistic behavior is now recognized to be an important component of nutritional ecology in both carnivorous and herbivorous species, including many beetle families (Englert and Thomas 1970; Beaver 1974; Dickinson 1992; Bartlett 1987; Alabi et al. 2008). This habit was historically viewed by an incidental outcome of unnaturally crowded laboratory situations with little ecological importance (Fox 1975), but it is increasingly acknowledged that cannibalism represents a potentially advantageous behavior (Richardson et al. 2010). Here we report on multiple cases of egg cannibalism, or conspecific oophagy, by adults of two species of passion vine (Passiflora Linnaeus: Passifloraceae) specialist flea beetles in the genus Disonycha Chevrolat (Coleoptera: Chrysomelidae: Galerucinae: Alticini). This is the first report of egg cannibalism from the Galerucinae, and to our knowledge, only the fourth report of egg cannibalism by adults in the Chrysomelidae; the other three reports are of adult Chrysomelinae species eating conspecific eggs (Dickinson 1992; McCauley 1992; Schrod et al. 1996). We conclude this note with several questions raised by our observations, followed by a discussion that may contribute to explanations of this behavior.

animal behavior and cognition↗

bioRxiv2019

Species specificity and intraspecific variation in the chemical profiles of Heliconius butterflies across a large geographic range

In many animals, mate choice is important for the maintenance of reproductive isolation between species. Traits important for mate choice and behavioural isolation are predicted to be under strong stabilising selection within species, however such traits can also exhibit variation at the population level driven by neutral and adaptive evolutionary processes. Here, we describe patterns of divergence among androconial and genital chemical profiles at inter- and intra-specific levels in mimetic Heliconius butterflies. Most variation in chemical bouquets was found between species, but there were also quantitative differences at the population level. We found a strong correlation between interspecific chemical and genetic divergence, however, this correlation varied in intraspecific comparisons. We identified indicator compounds characteristic of particular species that included known biologically active compounds, suggesting an approach for identification of candidate compounds for future behavioural studies in novel systems. Overall, the strong signal of species identity suggests a role for these compounds in species recognition, but with additional potentially neutral variation at the population level.

evolutionary biology↗

bioRxiv2018

Experimental manipulation of Heliconius warning patterns reduces harassment of previously mated females.

Why warning patterns are so diverse is an enduring evolutionary problem. Because predators learn to associate particular patterns with unpleasant experiences, an individuals risk of predation should decrease as the local density of its warning pattern increases. Heliconius butterflies, however, are known for their diversity of warning patterns, and the establishment of entirely new phenotypes is difficult to explain under strict frequency-dependent selection. One possibility is that during periods of relaxed selection, drift may allow new variants to rise above a threshold density until mimicry selection takes over. We propose an alternative hypothesis where novel pattern phenotypes arise due to a conflict of interests between the sexes. It is well established that male Heliconius use warning patterns as a mating cue. This will likely be beneficial to males as it will increase the efficiency of finding mates. However, already mated females may suffer fitness costs if these cues lead to harassment by males during oviposition or foraging. When constraints imposed by predation are locally relaxed, this could lead to rapid divergence in pattern phenotypes through chase-away sexual selection. To begin to test this hypothesis, we experimentally manipulated the warning patterns of mated Heliconius erato demaphoon females and recorded their interactions with conspecific males, and the effect of male presence on laying rate. As predicted, males interacted less with mated females whose red forewing band was blacked-out, as compared to control females whose warning pattern remained intact. We also show that females lay less eggs in the presence of males, but we were unable to detect a significant interaction between warning pattern treatment and the presence of males on female fecundity. Our results suggest that male attraction to conspecific warning patterns, may impose a previously unrecognized cost on Heliconius females.

evolutionary biology↗

bioRxiv2017

Diallel analysis reveals Mx1-dependent and Mx1-independent effects on response to influenza A virus in mice

1.Influenza A virus (IAV) is a respiratory pathogen that causes substantial morbidity and mortality during both seasonal and pandemic outbreaks. Infection outcomes in unexposed populations are affected by host genetics, but this host genetic architecture is not well understood. Here we obtain a broad view of how heritable factors affect a mouse model of response to IAV infection using an 8x8 diallel of the eight inbred founder strains of the Collaborative Cross (CC). Expanding on a prior statistical framework for modeling treatment response in diallels, we explore how a range of heritable effects modify acute host response to IAV through 4 days post-infection. Heritable effects in aggregate explained about 57% of the variance in IAV-induced weight loss. Much of this was attributable to a pattern of additive effects that became more prominent through day 4 post-infection and was consistent with previous reports of anti-influenza myxovirus resistance 1 (Mx1) polymorphisms segregating between these strains; the additive effects largely recapitulated haplotype effects observed at the Mx1 locus in a previous study of the incipient CC (pre-CC), and are also replicated here in a CC recombinant intercross (CC-RIX) population. Genetic dominance of protective Mx1 haplotypes was observed to differ by subspecies origin: relative to the domesticus null Mx1 allele, musculus acts dominantly whereas castaneus acts additively. After controlling for Mx1, heritable effects, though less distinct, accounted for about 34% of the phenotypic variance. Implications for future mapping studies are discussed.

genetics↗