Search results for "PARASEMIA"
showing 10 items of 36 documents
Tracking the evolution of warning signals
1996
EVOLUTIONARYstudies are hampered by a lack of experimental ways in which to test past events such as the origination of aposematism1–7, whereby unpalatable or poisonous prey signal their unprofitability, often by being warningly coloured. Inexperienced predators do learn to avoid unpalatable prey as a result of such signals8–10, but in addition there may be an inherited cautiousness about attacking when common or conspicuous warning signals are evident11–16. As current predators are not naive in the evolutionary sense, it is still not resolved3–7,17,18 whether aposematism originated only in aggregations of prey19,20 or among solitary prey as well21–23. Here we explore this controversy in ev…
Global phylogeography and geographical variation in warning coloration of the wood tiger moth (Parasemia plantaginis)
2015
Aim To investigate the phylogeography of the aposematic wood tiger moth (Parasemia plantaginis) across its Holarctic distribution and to explore how its genetic structure relates to geographical differences in hindwing warning coloration of males and females. Males have polymorphic hindwing coloration, while female hindwing coloration varies continuously, but no geographical analyses of coloration or genetic structure exist. Location The Holarctic. Methods We sequenced a fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 587 specimens. We also examined more current population structure by genotyping 569 specimens at 10 nuclear microsatellite loci. Species distribut…
Temporal relationship between genetic and warning signal variation in the aposematic wood tiger moth (Parasemia plantaginis).
2013
Many plants and animals advertise unpalatability through warning signals in the form of colour and shape. Variation in warning signals within local populations is not expected because they are subject to directional selection. However, mounting evidence of warning signal variation within local populations suggests that other selective forces may be acting. Moreover, different selective pressures may act on the individual components of a warning signal. At present, we have a limited understanding about how multiple selection processes operate simultaneously on warning signal components, and even less about their temporal and spatial dynamics. Here, we examined temporal variation of several w…
Changes in predator community structure shifts the efficacy of two warning signals in Arctiid moths
2013
Summary 1. Polymorphism in warning coloration is puzzling because positive frequency-dependent selection by predators is expected to promote monomorphic warning signals in defended prey. 2. We studied predation on the warning-coloured wood tiger moth (Parasemia plantaginis )b y using artificial prey resembling white and yellow male colour morphs in five separate populations with different naturally occurring morph frequencies. 3. We tested whether predation favours one of the colour morphs over the other and whether that is influenced either by local, natural colour morph frequencies or predator community composition. 4. We found that yellow specimens were attacked less than white ones rega…
Insect immunity: oral exposure to a bacterial pathogen elicits free radical response and protects from a recurring infection
2014
Background: Previous exposure to a pathogen can help organisms cope with recurring infection. This is widely recognised in vertebrates, but increasing occasions are also being reported in invertebrates where this phenomenon is referred to as immune priming. However, the mechanisms that allow acquired pathogen resistance in insects remain largely unknown. Results: We studied the priming of bacterial resi stance in the larvae of the tiger moth, Parasemia plantaginis using two gram-negative bacteria, a pathogenic Serratia marcescens and a non-pathogenic control, Escherichia coli. Asublethaloraldoseof S. marcescens provided the larvae with effective protection against an otherwise lethal septic…
Predator Mixes and the Conspicuousness of Aposematic Signals
2003
Conspicuous warning signals of unprofitable prey are a defense against visually hunting predators. They work because predators learn to associate unprofitability with bright coloration and because strong signals are detectable and memorable. However, many species that can be considered defended are not very conspicuous; they have weak warning signals. This phenomenon has previously been ignored in models and experiments. In addition, there is significant within- and among-species variation among predators in their search behavior, in their visual, cognitive, and learning abilities, and in their resistance to defenses. In this article we explore the effects of variable predators on models th…
To quiver or to shiver: increased melanization benefits thermoregulation, but reduces warning signal efficacy in the wood tiger moth
2013
Melanin production is often considered costly, yet beneficial for thermoregulation. Studies of variation in melanization and the opposing selective forces that underlie its variability contribute greatly to understanding natural selection. We investigated whether melanization benefits are traded off with predation risk to promote observed local and geographical variation in the warning signal of adult male wood tiger moths ( Parasemia plantaginis ). Warning signal variation is predicted to reduce survival in aposematic species. However, in P. plantaginis , male hindwings are either yellow or white in Europe, and show continuous variation in melanized markings that cover 20 to 90 per cent o…
Colour polymorphism torn apart by opposing positive frequency-dependent selection, yet maintained in space.
2015
Summary Polymorphic warning signals in aposematic species are enigmatic because predator learning and discrimination should select for the most common coloration, resulting in positive frequency‐dependent survival selection. Here, we investigated whether differential mating success could create sufficiently strong negative frequency‐dependent selection for rare morphs to explain polymorphic (white and yellow) warning coloration in male wood tiger moths (Parasemia plantaginis). We conducted an experiment in semi‐natural conditions where we estimated mating success for both white and yellow male moths under three different morph frequencies. Contrary to expectations, mating success was positi…
DIET QUALITY AFFECTS WARNING COLORATION INDIRECTLY: EXCRETION COSTS IN A GENERALIST HERBIVORE
2009
Aposematic herbivores are under selection pressure from their host plants and predators. Although many aposematic herbivores exploit plant toxins in their own secondary defense, dealing with these harmful compounds might underlay costs. We studied whether the allocation of energy to detoxification and/or sequestration of host plant defense chemicals trades off with warning signal expression. We used a generalist aposematic herbivore Parasemia plantaginis (Arctiidae), whose adults and larvae show extensive phenotypic and genetic variation in coloration. We reared larvae from selection lines for small and large larval warning signals on Plantago lanceolata with either low or high concentratio…
Environment-mediated morph-linked immune and life-history responses in the aposematic wood tiger moth
2012
1. Warning signals are expected to evolve towards conspicuousness and monomorphism, and thereby hamper the evolution of multiple colour morphs. Here, we test fitness responses to different rearing densities to explain colour polymorphism in aposematic wood tiger moth (Parasemia plantaginis) males. 2. We used larval lines sired by white or yellow adult males selected for small or large melanization patterns of coloration. We reared these selected lines either solitarily (favourable conditions) or in aggregations (challenged conditions), and followed their performance to adult stage. We tested whether differences in larval density affected life-history traits, adult melanin expression, adult …