Tropical ecology WBNZ800 Mimicry and other related strategies
Hoverfly (Sirphidae) Wasp (Vespidae)
Tomasz W. Pyrcz Zoological Museum Jagiellonian University www.mzuj.uj.edu.pl A clearwing butterfly of the subfamily Ithomiinae Mimicry was described based on the example of tropical butterflies
Henry Bates (1862) Fritz Müller (1878) MIMICRY
Mimicry is one of the fundamental issues of evolutionary biology
Entries on „mimicry” on the Internet (Google)
In English – 42 000 000! In Spanish – 978 000 In French – 611 000 In Polish – 46 700 MIMICRY
Resemblance
Camouflage
Signalling MIMICRY – a tripartite system
(model) similar appearance (mimic) true signal
false signal (operator)
Wickler, 1968 Vane-Wright, 1978 Mimicry definitions
Mimicry (general definition) is the similarity of one species to another which protects one or both.
Mimicry (Polish Wikipedia) – protective adaptations of animals (especially insects) consisting in that harmless animals look like animals able to protect themselves by taking their shapes or colours. They can also take shapes and colous of the environment in order to be more difficult to detect. Mimicry definitions
Mimicry (based on Wickler, 1968) is an evolutionary process in which an organism improves its fitness by modifying its appearance towards another organism.
Mimicry (Pihneiro, 2004) involves an organism (the mimic) which simulates signal properties of a second living organism (the model), which are received as signals of interest by a third living organism (the operator), such that the mimic gains in fitness as a result of the opertator identifying it as an example of the model
This definition does not say whether the fitness of model is affected! CRYPSIS /MIMESIS is not mimicry!
Differences between mimicry and crypsis:
Mimicry: 1. Mimic aims a response of the operator 2. Resemblance of the mimic modifies the fitness of the model Crypsis: 1. Cryptical species are invisible to the operator 2. Resemblance has no effect on the fitness of the model Crypsis = camouflage
A butterfly of the subfamily Satyrinae
Ventral side of the wings closely resemble the pattern of lichens Ventral surface of the wings resembles dead leaves
A butterfly of the subfamily Satyrinae
Crypsis = camouflage Camouflage – homomorphy i homochromy
A locust of the subfamily Gomphocerinae A grasshopper of the family Tettigonidae
Camouflage – homomorphy and homochromy Disruptive colours – colour patterns interfers in the predator perception of the real shape of the prey
Countershade – light ventral colours and dark dorsal colours convert the three dimesional the prey into an illusion of a two dimensional object Crypsis – disruptive colours
Logitudinal dorsal line of this toad is an additional element of its disruptive colours pattern When wings are wide open, the colour patterns of fore and hindwing alogns into a pattern resembling wood corch, and at the same time disrupting the true body axis.
A moth of the genusThysania
Crypsis – disruptive colours Vane-Wright’s unified mimicry system
I Synergic warning Mullerian II Synergic aggressive Angler fishes III Synergic defensive Automimicry of Danaus IV Synergic inviting Arithmetic
V Antergic inviting Maculinea myrmecophyly VI Antergic defensive Batesian VII Antergic aggressive Peckhammian, parasites VIII Antergic warning obnoxious Reduviids predators Key issues related with mimicry
THE OPERATOR
The identification of the operator is crucial. Without identifying the operator we cannot dissuss mimicry.
MODEL PROTECTION
Unpalatability as the protective measure is the backbone of the mimicry theory. Key issues related with mimicry
COEXISTENCE IN TIME AND SPACE
Microsympatry is the first precondition of turning up of mimicry. Most authors agree that mimics and models have to coexist in time and space so that the signal can be functional
RELATIVE FREQUENCY
All kinds of mimicry are frequency dependent. The theory of Batesian mimicry infers that the model has to be abundant in the environment so that the system can be operational, and most authors agree that it has to occur at higher frequency than the mimic. VI - Batesian mimicry MIMICRY in other words: DECEPTION
Mating moths of the family Syntomiidae, excellent mimics of wasps VI - Batesian mimicry
Day active moths of the family Tortricidae have a similar colour pattern and beahviour as toxic bugs VI - Batesian mimicry
Day active moths of the family Sesiidae have a similar colour patterns as wasps and bees VII - Myrmecomorphy – mimicry of ants by other organisms
Mimicry can be aggresive or defensive
Salticidae spiders copy the shape and behaviour of Oecophylla ants in order to prey on them V - Myrmecophily butterfly larvae and ants
Myrmecophily are different associations of ants with other organisms, butterflies, bugs, aphids, grasshoppers etc. Larvae of Lycaenidae produce sweet secretions which attract the ants, that take it to the nest, where they are given shelter from predators and parasitoids. Some caterpillars, such as M. arion feed on ants larvae. False eyes: „Owl eyes” of a Caligo butterfly (Brassolinae)
VI - Auto-mimicry? Defensive mimicry II – Auto-mimicry / Luring to baits
Deep sea angler fishes emit bioluminiscent light from the illicium - a fleshy head grow, a modified spine VI - Defensive mimicry Egg dummies
Pasion fruit, Passiflora, host plant of Heliconius butterflies produces galls resembling by the their shape and colours butterfly eggs V. Inviting mimicry Bee-like orchids
www.conservationreport.files.wordpress.com
The petals of thic orchid look like a female bee in order to attract male bees which take part in the pollinization of this flower. We have to be able to identify the operator. Otherwise, we can’t talk about mimicry.
MODEL
MIMIC
Striped hyena
Proteles
OPERATOR? Sex limited mimicry
Females of an Asian swallowtail Papilio polytes are polymorphic and mimic unpalatable Pachliopta species. Males are monomorphic and non-mimetic. Sex limited mimicry
Kunte, 2009 Mimicry used in phylogenetical studies Auto mimicry: when mimic and model belong to the same species male andromorphic female Papilio dardanus Papilio dardanus
Danaus sp. females
Amauris sp. Papilio
Amauris sp. dardanus
Some females of African swallowtail Papilio dardanus mimic not the obnoxious model Amauris but instead the male of its own species. „MULLERIAN MIMICRY” IS NOT MIMICRY!
Repeating the same aposematic colour pattern by protected species enhances the warning signal adressed to potential predators Enhancing the aposematic signal
Batesian mimicry: model’s fitness decreases Müllerian mimicry: model’s fitness increases ACCIDENTAL resemblances between insects are to be expected. The immense number of species and the necessary limitation in the variety of colours and patterns must lead to coincidences.
The coincidences would be relatively more numerous when the patterns are simple. Poulton, 1903 VI. Emsleyan/Mertensian mimicry
Non-venenous snake (Lampropeltis sp.) – on the right Venomous coral snake (Micrurus sp.) – on the left VI. Batesian mimicry: evidence from the field
Pfennig et al., 2004
Predators either prefer or reject ringed preys VI. Batesian mimicry: experimental evidence
Photo: Brandao (Flickriver)
Heliconius (Nymphalidae) and jacamars (Galbulidae) VI. Batesian mimicry: experimental evidence
Wild rufous-tailed jacamars (Calbula rujcaudu) prey frequently upon butterflies in Costa Rica.
Individually caged birds were tested with over 1000 butterflies of 14 morphs.
Both wild jacamars and the two captive individuals were able to capture and handle local butterflies.
Butterflies were recognized by the jacamars as prey through their movement.
Captive birds discriminated between an unacceptable group of butterflies, which generally fly slowly or regularly, are warningly coloured and mimetic, with transparent, or white, red, black coloration, and an acceptable group that generally fly fast or erratically, or are cryptic.
Chai, 1986 VI. Batesian mimicry: experimental evidence
Morphological and behavioural characteristics of butterflies help the jacamars to assess their palatability. Individuals of unacceptable butterflies were sight-rejected.
In cases when the above butterflies were attacked, they were quickly released and usually unharmed.
In contrast, palatable butterflies were usually quickly attacked and consumed.
Captive jacamars were able to discriminate between the very similar colour patterns of some Batesian mimics and their models, and could memorize the palatability of a large variety of butterflies.
Chai, 1986 VI. Batesian mimicry: experimental evidence
Captive female bird, after long periods without food, consumed many pierid and heliconiine butterflies that were consistently rejected by the male for their distasteful and dangerous qualities.
Chai, 1986 Locomotor mimicry
Locomotor and escape mimicry concepts (Srygley, 1999).
Motion of the prey increases selection against odd individuals.
Locomotor mimicry may occur between palatable species that are alike as a result of the so-called „unprofitable prey factor”.
By frustration learning, the predator associates the colour of the prey with unprofitability. IV. Arithmertic mimicry
A particular case of the synergic inviting mimicry (Vane-Wright, 1976), the "safety in numbers" and "lost in a crowd" effect
Adelpha in Venezuela have six local subspecies all characterised by HWD bands suffused along their distal edge with orange.
Arithmetic mimicry is a system acting through co-convergence of the participants signal,w hich increases its effectiveness, as in Müllerian mimicry,. IV. Arithmertic mimicry
Butterflies of the genus Actinote have the ability of syntesising strong cyagenic toxins for example linamarins Limacodidae moth caterpillar Parasitoid egg dummies
Warning – colours and shapes Mimicry strategies can shift within individual’s life span
First to fourth instar lavae of Paplio butterflies look like bird dropping Last instar changes into snake-like Dual signals camouflage and warning
North American moth of the Saturniidae family The effect of warning colours of this beattle is reinforced by the protrusions on the antennae
Signal interpretation problems: Aposematic? Caterpillars of the Saturniidae family Green colour of the body perfectly matches the shade of green of the host plant leaf
Setae and scoli reducing the possibility of parasitoid flies and wasps
Lighter band mimics a culm Thorough protection Mimicy is functional only when the model and the mimic coexist in time and space!
Different altitudinal -Different ranges altitudinal -Different ranges geographic -Overlapping ranges geographic ranges
-Overlapping altitudinal ranges -Overlapping geographic ranges The evolutionary rationale of (Batesian) mimicry: predator avoidance
When is mimicry ESS?
When predator’s pressure on survival is above a threshold limit
Signal (for example): bright colours..
…is aposematic and addressed to the predator
But if predators’s pressure is not a limiting factor
Signal’s function is different: directed to the mate – infraspecific communication THE PITFALLS OF ? INTERPRETATION Are insectivorous birds ? an important limiting factor controlling the populations of butterflies?
? ? Unprofitable prey factor
Predators learn that some preys are too diffucult to catch, thus consider them as „unprofitable” and do not prey upon them, except for opportunistic events.
? Does gain compensate the energy spent on its acquirementt ?
Too fast! Wings big Body too small!
Too small! Too difficult to detect! Mimicry case study: Lymanopoda and Cheimas butterflies
Sympatric species with similar colour patterns occur in the same areas Mimicry case study: Lymanopoda and Cheimas butterflies
Sympatric species with similar colour patterns occur in the same areas Mimicry case study: Lymanopoda and Cheimas butterflies
Sympatric species with similar colour patterns occur within same elevational bands Brown butterflies mimicry: no protection involved!
Colour pattern resemblance are common among sympatric species of the tribe Pronophilini Mimicry case study: Lymanopoda and Cheimas butterflies
ANTI-APOSTATIC SELECTION
Anti-apostatic selection is the selection against the odd individuals. It arises when preys are at high frequency and predators feed disproportionately on rare prey.
This process leads to a decrease in variation within prey populations.
Most evidence comes from experiments using artificial prey.
There are proofs that predators can be selective on prey frequency and target the individuals whose pattern is at low abundance. Mimicry case study: Lymanopoda and Cheimas butterflies
ANTI-APOSTATIC SELECTION
Anti-apostatic selection favours gregarious behaviour.
Anti-apostatic selection is theoretically unlikely to evolve when predators specialize on a given prey. If so, predation on rare phenotypes would be unprofitable energetically.
However, in a situation when preys are at high frequency and predation is random and/or opportunistic, the evolution of anti- apostatic selection is plausible. Resting moths: easy prey -ESS strategy: crypsis - No aposematic colours
Moth biomass exeeds the biomass of butterflies by several magnitudes! Recommended literature in Polish:
1. H. Krzanowska et al., 2002. Zarys mechanizmów ewolucji 2. J. Koszteyn, 2005. Zjawisko mimikry a problem orientacji i decepcji in English:
3. Ruxton, Sherratt & Speed, 2005. Avoiding attack What kind of mimicry would that be?
Spider looking like a bird dropping What kind of mimicry would that be?
Some ants resemble spiders