Kaikki aineistot
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Abstract Social information use is a widespread phenomenon across the animal kingdom and it affects various important aspects of animal behaviour. Animals observe and copy the behaviour of conspecifics and other species on the same trophic level in their own decision-making, e.g., in habitat or mate choice. Copying is adaptive only when it is selective. Thus, it would be important to understand when and which individuals should copy others, and which individuals they choose to copy and what are the consequences of social information use. In this thesis, I experimentally study these questions in wild animals living in natural conditions. By simulating arbitrary preference of great tits (Parus major), I demonstrated that the portrayed fitness does not affect the nest site choices of conspecifics, but the tit pairs with an old male prefer the nest site choices of good and poor conspecifics. Social information use among tits appears to be age- and sex-dependent. Pied flycatchers (Ficedula hypoleuca), however, selectively copy or reject a novel nest site feature preference (symbol attached to the nest box) of great tits experimentally manipulated to exhibit high or low fitness (clutch size), respectively. By offering pied flycatchers choice in nest boxes with alternative contents, I showed that nest take-overs of flycatchers are not a form of social information use, but seem to result from the reduced building effort required. Furthermore, by conducting a decoy and playback experiment, I showed that great tits covered eggs more efficiently in the presence of pied flycatchers. One function of egg covering behaviour seems to be a counter-adaptation to reduce information parasitism by pied flycatchers. My results demonstrate that the social transmission of behaviours across species can be highly selective in response to observed fitness, plausibly making the phenomenon adaptive. In contrast with the current theory of species coexistence, overlap between realized niches of species could dynamically increase or decrease, depending on the observed success of surrounding individuals. The social information revealed by success and behaviour of animals is a resource that can be used or concealed. It is a new kind of evolutionary and ecological factor which may affect the formation of ecosystems and species coevolution.
Social information transmission is important because it enables horizontal spread of behaviors, not only between conspecifics but also between individuals of different species. Because interspecific social information use is expected to take place among species with similar resource needs, it may have major consequences for the emergence of local adaptations, resource sharing, and community organization. Social information use is expected to be selective, but the conditions promoting it in an interspecific context are not well known. Here, we experimentally test whether pied flycatchers (Ficedula hypoleuca) use the clutch size of great tits (Parus major) in determining the quality of the observed individual and use it as a basis of decision making. We show that pied flycatchers copied or rejected a novel nest site feature preference of great tits experimentally manipulated to exhibit high or low fitness (clutch size), respectively. Our results demonstrate that the social transmission of behaviors across species can be highly selective in response to observed fitness, plausibly making the phenomenon adaptive. In contrast with the current theory of species coexistence, overlap between realized niches of species could dynamically increase or decrease depending on the observed success of surrounding individuals.
Background: Coevolution between pairs of different kind of entities, such as providers and users of information, involves reciprocal selection pressures between them as a consequence of their ecological interaction. Pied flycatchers ( Ficedula hypoleuca ) have been shown to derive fitness benefits (larger clutches) when nesting in proximity to great tits ( Parus major ), presumably because they this way discover and obtain information about nesting sites. Tits suffer from the resulting association (smaller clutches). An arms race between the tits (information host) and the flycatchers (information parasite) could thus result . Great tits often cover eggs with nesting material before, but not during incubation. We hypothesized that one function of egg-covering could be a counter-adaptation to reduce information parasitism by pied flycatchers. We predicted that tits should bring more new hair to cover their exposed eggs when a pied flycatcher is present near to tit nest than when a neutral (non-competing) species is present. We conducted decoy and playback experiment in Oulu and Turku, Finland. First, we removed and collected all the hair covering the tit eggs. Then, we measured how the perceived presence of flycatcher or waxwing ( Bombycilla garrulus ) affects tits' egg-covering by collecting and weighing the hair brought on the eggs and photographing the nest 24 h after the playback. Results: Tits brought more hair into the nest and covered the eggs more carefully after flycatcher treatment, compared to waxwing treatment. We also found that the tits in Oulu (over 600 km to north from Turku) had more hair on the top of their eggs in general. Conclusions: Together, these results suggest that the counter-adaptation function of egg-covering against information parasites may be an extension of original function to protect eggs from low temperatures.
Background Pesticides are identified as one of the major reasons for the global pollinator decline. However, the sublethal effects of pesticide residue levels found in pollen and nectar on pollinators have been studied little. The aim of our research was to study whether oral exposure to the thiacloprid levels found in pollen and nectar affect the learning and long-term memory of bumble bees. We tested the effects of two exposure levels of thiacloprid-based pesticide (Calypso SC480) on buff-tailed bumble bee (Bombus terrestris) in laboratory utilizing a learning performance and memory tasks designed to be difficult enough to reveal large variations across the individuals. Results The lower exposure level of the thiacloprid-based pesticide impaired the bees’ learning performance but not long-term memory compared to the untreated controls. The higher exposure level caused severe acute symptoms, due to which we were not able to test the learning and memory. Conclusions Our results show that oral exposure to a thiacloprid-based pesticide, calculated based on residue levels found in pollen and nectar, not only causes sublethal effects but also acute lethal effects on bumble bees. Our study underlines an urgent demand for better understanding of pesticide residues in the environment, and of the effects of those residue levels on pollinators. These findings fill the gap in the existing knowledge and help the scientific community and policymakers to enhance the sustainable use of pesticides.
Concept learning is considered a high-level adaptive ability. Thus far, it has been studied in laboratory via asocial trial and error learning. Yet, social information use is common among animals but it remains unknown whether concept learning by observing others occurs. We tested whether pied flycatchers (Ficedula hypoleuca) form conceptual relationships from the apparent choices of nest-site characteristics (geometric symbol attached to the nest-box) of great tits (Parus major). Each wild flycatcher female (n = 124) observed one tit pair that exhibited an apparent preference for either a large or a small symbol and was then allowed to choose between two nest-boxes with a large and a small symbol, but the symbol shape was different to that on the tit nest. Older flycatcher females were more likely to copy the symbol size preference of tits than yearling flycatcher females when there was a high number of visible eggs or a few partially visible eggs in the tit nest. However, this depended on the phenotype, copying switched to rejection as a function of increasing body size. Possibly the quality of and overlap in resource use with the tits affected flycatchers' decisions. Hence, our results suggest that conceptual preferences can be horizontally transmitted across coexisting animals, which may increase the performance of individuals that use concept learning abilities in their decision-making.
A small brain and short life allegedly limit cognitive abilities. Our view of invertebrate cognition may also be biased by the choice of experimental stimuli. Here, the stimuli (color) pairs used in the match-to-sample tasks affected the performance of buff-tailed bumblebees (Bombus terrestris). We trained the bees to roll a tool, a ball, to a goal that matched its color. Bees trained with a yellow-and-orange/red stimuli pair took more training bouts to reach our color-matching criterion than those trained with a blue-and-yellow stimuli pair. When assessing the bees’ concept learning ability in a transfer test with a novel color, the bees trained with blue and yellow (novel color: orange/red) were highly successful, the bees trained with blue and orange/red (novel color: yellow) did not differ from random, and those trained with yellow and orange/red (novel color: blue) failed the test. These results highlight that stimulus salience can affect our conclusions on test subjects’ cognitive ability. Therefore, we encourage paying attention to stimulus salience (among other factors) when assessing the cognition of invertebrates.
Recent work has shown that animals frequently use social information from individuals of their own species as well as from other species; however, the ecological and evolutionary consequences of this social information use remain poorly understood. Additionally, information users may be selective in their social information use, deciding from whom and how to use information, but this has been overlooked in an interspecific context. In particular, the intentional decision to reject a behaviour observed via social information has received less attention, although recent work has indicated its presence in various taxa. Based on existing literature, we explore in which circumstances selective interspecific information use may lead to different ecological and coevolutionary outcomes between two species, such as explaining observed co-occurrences of putative competitors. The initial ecological differences and the balance between the costs of competition and the benefits of social information use potentially determine whether selection may lead to trait divergence, convergence or coevolutionary arms race between two species. We propose that selective social information use, including adoption and rejection of behaviours, may have far-reaching fitness consequences, potentially leading to community-level eco-evolutionary outcomes. We argue that these consequences of selective interspecific information use may be much more widespread than has thus far been considered.
Euroopan Unionissa on asetettu tavoitteita päästöjen vähentämiseksi ja uusiutuvan energian lisäämiseksi. Helsingin kaupungin valtuusto on asettanut entiselle Helsingin Energialle, nykyiselle Helen Oy:lle, tavoitteeksi vähentää 20 % hiilidioksidipäästöjä vuoden 1990 tasosta ja lisätä uusiutuvan osuus 20 %:iin vuoteen 2020 mennessä. Helen on käynnistänyt kehitysohjelman tämän tavoitteen saavuttamiseksi ja asettanut tavoitteeksi hiilidioksidineutraalintuotannon vuonna 2050. Puupelleteistä tiedetään haihtuvan merkittäviä määriä hiilimonoksidia ja aldehydejä. Hiilimonoksidia muodostuu tyydyttämättömien rasvahappojen hapettumisreaktiosta. Reaktiomekanismia ei tunneta, mutta sen tiedetään alkavan noin plus viidessä lämpöasteessa ja kiihtyvän lämpötilan noustessa. Tehtyjen laboratoriokokeiden perusteella hiilimonoksidia haihtui merkittäviä määriä, mutta aldehydipitoisuudet olivat erittäin pieniä. Salmisaaren voimalaitosalueella suoritetussa työhygieenisessä mittauksessa Työterveyslaitos tutki pellettejä kuljettavan rekan kuljettajan altistumista. Selvityksessä todettiin, että kuljettaja altistui korkeille määrille puupölyä, mutta altistuminen kesti yhteensä vain 11 minuuttia. Selvityksen perusteella altistuminen oli kestoltaan niin lyhyt, joten merkittäviä toimenpiteitä ei nähty tarpeelliseksi. Puupölyn noustessa ilmaan aiheuttaa se erittäin herkästi räjähtävän seoksen. Puupölyn ja ilman seoksen tarvitsema minimi syttymisenergia on kymmeniä kertoja hiilipölyn vastaavaa pienempi. Tämä tekee puhtaanapidosta erittäin tärkeätä, koska puupölyä ei saa päästä kertymään pinnoille. Pölyräjähdystä vastaan hiilimyllyissä voidaan suojautua myös räjähdyksen tukahduttamisjärjestelmällä. Se estäisi mahdollisen hiilimyllyssä tapahtuneen räjähdyksen aiheuttamasta merkittäviä vahinkoja rakenteisin ja parantaisi lähellä työskentelevien turvallisuutta. Automaatiojärjestelmästä kerättyjen havaintojen perusteella hiilimonoksidin muodostuminen siiloissa ei ole kovinkaan merkittävää. Pelleteissä tunnettua itselämpenemistä ei myöskään havaittu tutkimalla siilojen vapaan ilmatilan lämpötilaa. Tutkimuksen perusteella tosin voidaan olettaa, että itselämpenemistä ei kuitenkaan pystytä havaitsemaan tutkimalla vapaan ilmatilan lämpötilaa. Itselämpenemisen havaitsemiseen tarvittaisiin monimutkaisempia siilon ympärillä tai pellettikasan keskelle ulottuvia lämpötilamittareita. Pellettien nopean kiertonopeuden takia niille ei kuitenkaan ole tarvetta. Tämän tutkimuksen perusteella pellettien poltto tuo monia uusia erityisesti turvallisuuteen liittyviä asioita. Merkittävimpinä näistä on mahdollinen pölyräjähdys. Pelleteissä yleisesti tunnetut kaasujen syntymisen ja itselämpenemisen eivät tämän tutkimuksen perusteella aiheuta tarvetta toimenpiteille.
Habitat loss and degradation are the main threats to biodiversity worldwide. For example, nearly 80% of peatlands in southern Finland have been drained. There is thus a need to safeguard the remaining pristine mires and to restore degraded ones.Ants play a pivotal role in many ecosystems and like many keystone plant species, shape ecosystem conditions for other biota. The effects of mire restoration and subsequent vegetation succession on ants, however, are poorly understood. We inventoried tree stands, vegetation, water-table level, and ants (with pitfall traps) in nine mires in southern Finland to explore differences in habitats, vegetation and ant assemblages among pristine, drained (30–40 years ago) and recently restored (1–3 years ago) pine mires. We expected that restoring the water-table level by ditch filling and reconstructing sparse tree stands by cuttings will recover mire vegetation and ants. We found predictable responses in habitat structure, floristic composition and ant assemblage structure both to drainage and restoration. However, for mire-specialist ants the results were variable and longer-term monitoring is needed to confirm the success of restoration since these social insects establish perennial colonies with long colony cycles. We conclude that restoring the water-table level and tree stand structure seem to recover the characteristic vegetation and ant assemblages in the short term. This recovery was likely enhanced because drained mires still had both acrotelm and catotelm, and connectedness was still reasonable for mire organisms to recolonize the restored mires either from local refugia or from populations of nearby mires.
Abstract Quantitative abilities are widely recognized to play important roles in several ecological contexts, such as foraging, mate choice, and social interaction. Indeed, such abilities are widespread among vertebrates, in particular mammals, birds, and fish. Recently, there has been an increasing number of studies on the quantitative abilities of invertebrates. In this review, we present the current knowledge in this field, especially focusing on the ecological relevance of the capacity to process quantitative information, the similarities with vertebrates, and the different methods adopted to investigate this cognitive skill. The literature argues, beyond methodological differences, a substantial similarity between the quantitative abilities of invertebrates and those of vertebrates, supporting the idea that similar ecological pressures may determine the emergence of similar cognitive systems even in distantly related species.
Using social information can be an efficient strategy for learning in a new environment while reducing the risks associated with trial-and-error learning. Whereas social information from conspecifics has long been assumed to be preferentially attended by animals, heterospecifics can also provide relevant information. Because different species may vary in their informative value, using heterospecific social information indiscriminately can be ineffective and even detrimental. Here, we evaluated how selective use of social information might arise at a proximate level in bumblebees (Bombus terrestris) as a result of experience with demonstrators differing in their visual appearance and in their informative value as reward predictors. Bumblebees were first trained to discriminate rewarding from unrewarding flowers based on which type of “heterospecific” (one of two differently painted model bees) was next to each flower. Subsequently, these bumblebees were exposed to a novel foraging context with two live painted bees. In this novel context, observer bumblebees showed significantly more social information-seeking behavior towards the type of bees that had predicted reward during training. Bumblebees were not attracted by paint-marked small wooden balls (moved via magnets) or paint-marked non-pollinating heterospecifics (woodlice; Porcellio laevis) in the novel context, indicating that bees did not simply respond to conditioned color cues nor to irrelevant social cues, but rather had a “search image” of what previously constituted a valuable, versus invaluable, information provider. The behavior of our bumblebees suggests that their use of social information is governed by learning, is selective, and extends beyond conspecifics.
Pollinator decline is a grave challenge worldwide. One of the main culprits for this decline is the widespread use of, and pollinators' chronic exposure to, agrochemicals. Here, we examined the effect of a field-realistic dose of the world's most commonly used pesticide, glyphosate-based herbicide (GBH), on bumblebee cognition. We experimentally tested bumblebee (Bombus terrestris) color and scent discrimination using acute GBH exposure, approximating a field-realistic dose from a day's foraging in a patch recently sprayed with GBH. In a 10-color discrimination experiment with five learning bouts, GBH treated bumblebees' learning rate fell to zero by third learning bout, whereas the control bees increased their performance in the last two bouts. In the memory test, the GBH treated bumblebees performed to near chance level, indicating that they had lost everything they had learned during the learning bouts, while the control bees were performing close to the level in their last learning bout. However, GBH did not affect bees' learning in a 2-color or 10-odor discrimination experiment, which suggests that the impact is limited to fine color learning and does not necessarily generalize to less specific tasks or other modalities. These results indicate that the widely used pesticide damages bumblebees' fine-color discrimination, which is essential to the pollinator's individual success and to colony fitness in complex foraging environments. Hence, our study suggests that acute sublethal exposure to GBH poses a greater threat to pollination-based ecosystem services than previously thought, and that tests for learning and memory should be integrated into pesticide risk assessment.
A growing number of studies have demonstrated that heterospecific individuals with overlapping resource needs – putative competitors – can provide information to each other that improves the outcomes of decisions. Our studies using cavity nesting resident tits (information provider) and migratory flycatchers (Ficedula spp., information user) have shown that selective interspecific information use (SIIU) can result in flycatchers copying and rejecting the apparent nest-site feature preferences of tits, depending on a perceivable fitness correlate (clutch size) of the tits. ese, and other results on the interspecific information use, challenge the predictions of traditional theory of species coexistence. Recently, Slagsvold and Wiebe (2017) proposed an alternative hypothesis, the owner aggression hypothesis (OAH), to explain our results. eir main points of critique are: 1) a lack of evidence that flycatchers make visits into tit nests prior to nesting and 2) flycatchers do not have an ability to assess tit clutch size. According to Slagsvold and Wiebe, interspecific aggression between tits and flycatchers, not infor-mation use, is the mechanism explaining our results. In this reply we show that part of Slagsvold and Wiebe’s criticism is based on mischaracterization of the assumptions of SIIU, resulting in misinterpretations of our results. We also provide new evidence that flycatchers (mostly males) frequently visit tit nests prior to settlement and can acquire information about tit clutch size and thereby on the quality of the tutoring tit individ-ual and its decisions. In short, as intriguing as OAH is, we suggest that 1) some of the assumptions are highly speculative and lack evidence, while 2) our earlier experiment (Loukola et al. 2013) has clearly demonstrated the importance of the visible clutch size of tits for flycatcher decisions. erefore, SIIU can more parsimoniously than OAH explain the behaviour of flycatchers.
Abstract Background: Pesticides are identified as one of the major reasons for the global pollinator decline. However, the sublethal effects of pesticide residue levels found in pollen and nectar on pollinators have been studied little. The aim of our research was to study whether oral exposure to the thiacloprid levels found in pollen and nectar affect the learning and long-term memory of bumble bees. We tested the effects of two exposure levels of thiacloprid-based pesticide (Calypso SC480) on buff-tailed bumble bee (Bombus terrestris) in laboratory utilizing a learning performance and memory tasks designed to be difficult enough to reveal large variations across the individuals. Results: The lower exposure level of the thiacloprid-based pesticide impaired the bees’ learning performance but not long-term memory compared to the untreated controls. The higher exposure level caused severe acute symptoms, due to which we were not able to test the learning and memory. Conclusions: Our results show that oral exposure to a thiacloprid-based pesticide, calculated based on residue levels found in pollen and nectar, not only causes sublethal effects but also acute lethal effects on bumble bees. Our study underlines an urgent demand for better understanding of pesticide residues in the environment, and of the effects of those residue levels on pollinators. These findings fill the gap in the existing knowledge and help the scientific community and policymakers to enhance the sustainable use of pesticides.
Abstract Most of the studies on learning in bees have focused on the foraging context; we know little about the preferences and cognitive processes in nest-site selection, especially in solitary bees. The majority of the bee species are solitary and in contrast to eusocial bees, solitary bees’ cognition and social information use have remained largely unstudied. Solitary cavity-nesting mason bees (Osmia spp.) are an ideal system to study interspecific information use in nest choice in the wild as many species share similar nesting requirements. Here, we show that the blue mason bee (O. caerulescens) and the orange-vented mason bee (O. leaiana) examine hallmarks of parasitization of the nests of red mason bees (O. bicornis) before deciding where to establish their own nests. They were also presented with contextual cues (geometric symbols) that could be linked to parasitization by observational learning. Subjects subsequently had the choice of nesting in a nest site marked by the symbol that matched, or did not match, the one seen at the parasitized or healthy nest. We show that the bees copied and rejected the symbol of the examined nest manipulated to exhibit successful and unsuccessful nesting, respectively. We conclude that solitary bees use interspecific information in their nest-site selection. In contrast with current theories of species coexistence, niche overlap between species may dynamically change depending on the observed success of surrounding individuals.