The evolution of aposematism, a phenomenon where prey species conspicuously advertise their unprofitability to predators, is puzzling. How did conspicuousness evolve, if it simultaneously increased the likelihood of an inexperienced predator to detect the prey and presumably kill it? Antiapostatic selection, where rare prey is predated relatively more often, is considered as another major difficulty for aposematism to evolve. However, the risk of being conspicuous in low frequencies has not been experimentally tested. We designed an experiment to test how frequency (4%, 12%, 32%) of conspicuous aposematic prey and its dispersion type (solitary vs. aggregated) affect an initial predation risk of the prey and in avoidance learning of predators. Wild great tits ( Parus major ) were predators on artificial prey in a “novel world.” The relative mortality of aposematic prey was antiapostatic, thus the frequency-dependent predation was most severe at low frequencies. In all frequencies, aggregated aposematic prey survived better than solitary prey. Surprisingly, learning was not determined by a fixed number of unpalatable prey eaten, but at low frequencies fewer aposematic individuals eaten generated predators' avoidance learning. However, per-capita risk for the prey remained highest at low frequencies. Our results underscore the problems of initial evolution of rare conspicuous morphs. Aggregated prey suffered less from predation, indicating selective advantage of aggregation over solitary living for a conspicuous individual.
Additional Affiliation(s) In the published article, there was an error regarding the affiliation for **Diana Abondano Almeida**. As well as having affiliation(s) ** **, they should also have ** Department of Wildlife-/Zoo-Animal-Biology and Systematics, Faculty of Biological Sciences, Goethe Universität, Frankfurt, Germany**. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.
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 concentration of iridoid glycosides (IGs). Larvae disposed of IGs effectively; their body IG content was low irrespective of their diet. Detoxification was costly as individuals reared on the high IG diet produced fewer offspring. The IG concentration of the diet did not affect larval coloration (no trade-off) but the wings of females were lighter orange (vs. dark red) when reared on the high IG diet. Thus, the difference in plant secondary chemicals did not induce variation in the chemical defense efficacy of aposematic individuals but caused variation in reproductive output and warning signals of females.
Abstract 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 distribution modelling for present conditions and the Last Glacial Maximum ( LGM ) was performed to help understand genetic structure. Geographical patterns in hindwing warning coloration were described from 1428 specimens and compared to the genetic analyses. Results We found only two instances of genetic divergence that coincided with distinct, yet imperfect, shifts in male hindwing coloration in the Caucasus region and Japan. A shift in female hindwing colour did not appear to be associated with genetic structure. A change from sexual monomorphism to sexual dimorphism was also observed. Mitogenetic (mt DNA ) structure does not show the influence of glacial refugia during the LGM . Climate shifts following the LGM appear to have isolated the red Caucasus populations and other southerly populations. Populations at opposite ends of the moth's distribution showed high levels of differentiation in the microsatellite data analysis compared to the shallow mitogenetic structure, supporting a more recent divergence. Main conclusions Parasemia plantaginis populations appeared to have been historically well connected, but current populations are much more differentiated. This raises the possibility that incipient speciation may be occurring in portions of the species' distribution. Some changes in colour align to genetic differences, but others do not, which suggests a role for selective and non‐selection based influences on warning signal variation.
This data is from the experiment investigating social avoidance learning in wild-caught great tits, conducted at Konnevesi Research Station in Central Finland during winter 2017. Sheet 1 (“main data”) contains data from the main avoidance learning experiment, including individual attributes (sex, age, weight etc.), experimental treatments and individuals’ foraging choices in the learning trials. Sheet 2 (“preference test”) contains data from the initial preference test of the symbols that were used in the experiment, and Sheet 3 (“visibility test”) data from the initial visibility test of the same symbols.
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