Search results for "puolustusmekanismit"
showing 10 items of 24 documents
A synthesis of deimatic behaviour
2022
Deimatic behaviours, also referred to as startle behaviours, are used against predators and rivals. Although many are spectacular, their proximate and ultimate causes remain unclear. In this review we aim to synthesise what is known about deimatic behaviour and identify knowledge gaps. We propose a working hypothesis for deimatic behaviour, and discuss the available evidence for the evolution, ontogeny, causation, and survival value of deimatic behaviour using Tinbergen's Four Questions as a framework. Our overarching aim is to direct future research by suggesting ways to address the most pressing questions in this field. peerReviewed
Maintenance of variation in warning signals under opposing selection pressures
2008
Kaikki eliöt ovat jotain kautta yhteydessä toisiin eliöihin erilaisten vuorovaikutussuhteiden kautta. Tyypillisesti vihollisiakaan ei ole vain yhtä, vaan useita erilaisia, joiden määrät ja tiheydet vaihtelevat luonnossa. Useisiin vastakkaisiin ja vaihteleviin valintapaineisiin on hankalaa sopeutua.Tilanne on haaste myös tutkijalle, sillä on vaikeampaa tutkia useampia valintapaineita samanaikaisesti kuin vain yhtä kerrallaan. Eläinten väritys antaa kuitenkin hyvän mahdollisuuden useiden samanaikaisten valintapaineiden tutkimiselle. Väritystä ja sen muuntelua on helppo havaita ja värityksellä on suuri merkitys eläimen hengissä selviytymisen kannalta.Carita Lindstedtin väitöskirjatutkimuksen l…
7. luokalle siirtyminen oppilaiden kokemana
2002
Testing the effectiveness of pyrazine defences against spiders
2020
Insects live in a dangerous world and may fall prey to a wide variety of predators, encompassing multiple taxa. As a result, selection may favour defences that are effective against multiple predator types, or target-specific defences that can reduce predation risk from particular groups of predators. Given the variation in sensory systems and hunting tactics, in particular between vertebrate and invertebrate predators, it is not always clear whether defences, such as chemical defences, that are effective against one group will be so against another. Despite this, the majority of research to date has focused on the role of a single predator species when considering the evolution of defended…
Experiments on defensive mimicry : linkages between predator behaviour and qualities of the prey
2006
Myrkylliset tai pahanmakuiset lajit voivat puolustautua saalistajia vastaan mainostamalla syömäkelvottomuuttaan näkyvin varoitussignaalein kuten värein. Saalistajien on tavallisesti opittava kokeilemalla välttämään pahoja ja signaloivia eli aposemaattisia lajeja. Varoitussignaaleja myös jäljitellään luonnossa. Batesin mimikria on ilmiö, jossa syömäkelpoinen matkijalaji suojautuu saalistajilta jäljittelemällä aposemaattisen mallilajin signaalia. Müllerin mimikriassa taas aposemaattiset ja ”näköislajit” käyttävät keskenään samanlaisia signaaleja.Loisteliaimmat esimerkit mimikriasta ovat trooppisia perhosia. Väitöskirjassaan Ihalainen tutki, miten samanlainen signalointi ja maku vaikuttavat sa…
Näennäinen kasvu ja välttelyn taktiikat määrittämässä opiskelijaryhmän omatoimista työskentelyä
2012
Tutkimuksessa tarkasteltiin opiskelijaryhmän työskentelyä estäviä puolia silloin, kun ryhmä toimii itsenäisesti ilman kouluttajia. Huomion kohteena olivat erityisesti työskentelyn piilevät ja tiedostamattomat puolet. Tutkimuskohteena oli Jyväskylän yliopiston 13-henkinen opiskelijaryhmä, joka opiskeli toista opintovuottaan integraatiokoulutuksessa. Aineisto kerättiin havainnoimalla pääasiassa ryhmän itsenäisiä tapaamisia lukuvuonna 2010-2011 sekä teettämällä opiskelijoilla kirjoitelmia lukuvuoden kuluessa. Lisäksi aineistoon kuului opiskelijoiden tekemä ryhmätyö heidän sanomattomista säännöis-tään sekä opiskelijoiden sähköpostiviesti ohjaajille. Aineistossa ilmeneviä teemoja tulkittiin niid…
The price of safety: food deprivation in early life influences the efficacy of chemical defence in an aposematic moth
2018
Aposematism is the combination of a primary signal with a secondary defence that predators must learn to associate with one another. However, variation in the level of defence, both within and between species, is very common. As secondary defences influence individual fitness, this variation in quality and quantity requires an evolutionary explanation, particularly as it may or may not correlate with variation in primary signals. The costs of defence production are expected to play a considerable role in generating this variation, yet studies of the cost of chemical defence have focused on species that sequester their defences, while studies in species that produce them de novo are scarce. …
Multimodal Aposematic Defenses Through the Predation Sequence
2021
Aposematic organisms warn predators of their unprofitability using a combination of defenses, including visual warning signals, startling sounds, noxious odors, or aversive tastes. Using multiple lines of defense can help prey avoid predators by stimulating multiple senses and/or by acting at different stages of predation. We tested the efficacy of three lines of defense (color, smell, taste) during the predation sequence of aposematic wood tiger moths (Arctia plantaginis) using blue tit (Cyanistes caeruleus) predators. Moths with two hindwing phenotypes (genotypes: WW/Wy = white, yy = yellow) were manipulated to have defense fluid with aversive smell (methoxypyrazines), body tissues with a…
Multiple modalities in insect warning displays have additive effects against wild avian predators
2019
Allocation to different components of defence has been suggested as an explanation for the existence of multiple aposematic morphs in a single population. We tested whether there are trade-offs between warning colouration and chemical defence or whether these have an additive effect when combined, using blue tits (Cyanistes caeruleus) as predators and the polymorphic wood tiger moth (Arctia plantaginis) as prey. We used artificial edible models (with and without the moths’ defensive fluids) with paper wings whose colour and pattern properties matched those of real moths. When the models were presented sans defensive fluids or when the fluids were presented without colour cues, we detected n…
Can warning signals be honest? : wing colouration and the strength of chemical defence in the female wood tiger moth (Parasemia plataginis)
2016
The warning displays of aposematic organisms signal to predators that they possess a secondary defence and are unprofitable. Within species variation exists in the strength of the signal and defence. As natural selection is expected to favour higher levels of defence, variation in such traits requires explanation. One hypothesis is that the strength of primary and secondary defences are correlated as they reflect the condition of the signaller. This study explores if variation in individual conspicuousness is an honest signal of the level of defence in the wood tiger moth (Parasemia plantaginis). P. plantaginis has conspicuous hind wing warning colouration, which in females varies from yell…