adaptive coloration - auburn university

adaptive coloration

crypsis, etc.

concealment,

advertisement,

and disguise

Much of the results of Natural Selection can be seen in the color, pattern, and form

of organisms. Explaining the adaptive significance of how organisms look is helpful

in understanding how natural selection operates. Understanding the adaptive

significance of traits involves a speculation of what type was selected for in the

evolutionary past and what the selection pressures were. Having words to

describe these things enhances one’s enjoyment and understanding of the world of

nature.

What follows is a list of vocabulary used to describe various categories of adaptive

coloration, especially in animals. Study these terms for test 3. We will have a brief

review before the test.

Crypsis – achieving concealment

Eucrypsis - concealment through color and/or pattern.

homochromy – body color matches the background

homochromy

glasswinged butterfly

“transparency”

Sometimes crypsis is as simple

as being invisible, or almost.

disruptive coloration – when a color pattern breaks up the body outline

countershading

lighter color below and darker above –

Counters the effect of sunlight and shade on

a 3-dimensional object. Functions for crypsis

in aquatic or terrestrial environments.

protective resemblance – cryptic resemblance or mimesiswhen an organism looks like something else in its environment

sargassum fish

in Sargassum

protective resemblance

Lithops, stone plant

protective resemblance (mimesis)

Behavior may play an important part in crypsis.

broken-twig moth

dead-leaf butterfly

katydid

Bizarre patterns, shapes:

Some organisms benefit from an

appearance that just doesn’t look

like what it is. This spider, for

instance, may not be noticed by

birds in search of spider prey

because it doesn’t really look like

a spider.

Pseudocephalism

A predator may not recognize

prey, may be frightened by

what appears to be a larger

organism, or may be confused

by what direction they will

move in escape.

rubber boa

Pseudocephalism

shock patterns

False eyes or other patterns

may produce a startle effect

when revealed suddenly.

The Io moth has more than one “trick up its sleeve.”

Non-cryptic coloration:Aposematism = advertisement of noxiousness

Individuals benefit from bright, easy to see and easy to remember coloration

(or sound) when learned predators avoid them because of association with a

bad experience.

It is sometimes said that a rattlesnake is a “gentleman”

because he warns before he bites. Does he really do this for

your benefit? Its best not to call this “warning coloration.”

aposematism

What noxiousness does

each of these have to

advertise?

Let’s review what we’ve covered so far:

Adaptive Coloration

crypsis

eucrypsis

homochromy

transparency

disruptive coloration

countershading

protective resemblance

bizarre pattern/shape

pseudocephalism

shock pattern

aposematism

Next….

mimicry – mimicry is involved when one organism looks specifically like

another organism, in a non-cryptic way, and gains advantage over predators

or prey. There are several types.

Mimicry

Noncryptic resemblance between two or more

species giving one or both a selective

advantage in relation to predators or prey.

Batesian Mimicry

.Also known as Pseudaposematism

a non-noxious mimic looks like a noxious model and is avoided by

experienced, would-be predators.

Model = noxious/aposematic

Mimic = non-noxious

Dupe - receives signalal

bee fly

Other examples of Batesian Mimicry

AR Wallace frequency criterion –

The proposed idea that the presence of the mimic reduces the

effectiveness of aposematism of the model; that models should be

more abundant than mimics.

• Not necessarily so. Data show otherwise. (One bad

experience produces a powerful learning experience.)

mimic spider model lady beetle

Other examples of Batesian mimicry

Heliobolus lugubris lizards mimic oogpister beetle

Oogpister beetles produce a noxious secretion that

protects them from predators. They advertise this with bold

patterns and a slow distinctive walk. Young lizards of this

species mimic the pattern and behavior of the beetles.

Their success is evidenced by a lower rate of tail breakage

than in other species.

more Batesian mimicry

Behavioral Batesian Mimicry –

eg. woodboring beetle and circus beetle

The circus beetle produces a noxious spray to defend itself

against predators and advertises this with a head stand. The

harmless woodboring beetle mimics the behavior.

Other interesting observations of Batesian mimicry:

Geographical separation of model and mimic has been observed in cases of

migrating bird predators.

Data have shown that in insects, models may have tougher exoskeleton than

mimics – can you explain why?

olfactory Batesian mimicry has been proposed for stink bugs,

some of which taste bad and others that do not.

Batesian con’t.

Monarch and viceroy butterflies are often considered the classic example of

Batesian mimicry – Monarchs feed on milkweed as caterpillars and

accumulate toxic cardiac glycosides – they are the model. Viceroys are

usually non-noxious and are the mimic. Birds are the dupes.

BUT - Some monarchs are non-noxious, yet benefit from looking like the

noxious members of their own species – this is called Automimicry.

ALSO – Viceroys are sometimes noxious themselves and benefit by sharing

aposematic coloration with monarchs. This is called Mullerian Mimicry.

monarch viceroy

Mullerian MimicryAlso called synaposematism.

Shared aposematism. All species

are co-models. This is often seen in

tropical butterflies, all of which are

toxic and protected by aposematism.

By their similarity they share the cost

(learning experience of predators).

Each individual benefits from the

likelihood that they will be avoided by

predators.

Helioconus spp.

Lycorea sp.

Mertensian Mimicry

This type of mimicry has been proposed to explain cases of snakes, or other

prey, so deadly that learning by predators is not possible. The idea is that

deadly snakes mimic a less dangerous species for which aposematism is

plausible. The classic example is the deadly coral snake (highly toxic),

suggested to mimic the moderately toxic false coral snake, which is also

mimicked by the non-toxic milk snake.

Mertensian Mimicry







It is no longer considered to be a valid idea as data have shown that coral

snake bites are not always fatal and their aposematism is functional.

X

Mertensian Mimicry









Back to the original idea…..If coral snakes are the model for mimicry by milk

snakes, what should we call it?

If coral snakes and false coral snakes share similar aposematism, what should

we call it?

X

Mertensian Mimicry









Back to the original idea…..If coral snakes are the model for mimicry by milk

snakes, what should we call it? Batesian mimicry

If coral snakes and false coral snakes share similar aposematism, what should

we call it? Mullerian mimicry

X

Aggressive Mimicry

Also called Peckhamian mimicry

This is mimicry by an “exploiter,” usually a predator, to gain advantage over

their prey, or “exploited.”

Sometimes the predator resembles the prey and it is likened to “a wolf in

sheep’s clothing”

ex. European cuckoo – a nest parasite. They lay eggs in the nests of

other species. Their eggs vary but always resemble the eggs of the

host species. Can you spot which is the cuckoo egg in the pictures

below?

Aggressive MimicrySometimes the exploiter resembles a helpful species

ex. Sabre-tooth blenny and cleaner wrass

Cleaner wrasses set up stations and experienced fish stop

by to be cleaned of parasites, etc……but they may get a

surprisie as a blenny takes a bite out of them!

more Aggressive mimicryExploiter resembles harmless species

ex. Zone Tailed Hawk resembles a vulture

Many small mammals flee from the sight of a hawk, but are not

alarmed by harmless vultures. This species has wing tips and flight

pattern that fool them.

Aggressive mimicry con’t.

Here are several good examples of the exploiter resembling an edible species.

angler fish’s lure

young cottonmouth – colorful wiggling tail

alligator snapping turtle’s tongue appendage

Asian flower mantid

Aggressive mimicry con’t

Freshwater mussels of the family Unionidae have glochidia larvae that are

parasitic on fish. Several species have amazing lures that attract fish and

increase the likelihood that their larvae will find a host.

glochidium

superconglutinate – a packet of

glochidia dangle downstream at the

end of a cord of mucus.


Auditory Aggressive Mimicry

African crowned eagles mimic the call of

their monkey prey.

Olfactory Aggressive Mimicry

Bolas spiders swing a sticky web that

smells like female moth pheromone.

Several species of carrion flowers look and

smell like carrion, attracting carrion flies as

pollinators. Drakea livida

Mastophora hutchinsoni

In what has been coined Pseudocopulation, orchids of the genus, Ophrys,

mimic female wasps. In repeated attempts to “mate” with the flower, males

transfer pollinia, packets of pollen.



Photomimicry is involved when the female of certain species of lightning

beetle mimic the flash pattern of other species. Unknowing males are

attracted to the flash, but meet with a predator instead of a willing mate!

Molecular Mimicry is involved when certain parasites mimic host antigens

and avoid an antibody response.

Wasmannian Mimicry

mimicry by commensals

Commensals often mimic a host and receive a benefit, but with no exploitation of the host.

For ex. inquilines (organisms that live within the home of another) may mimic the home-maker. Here are darkling beetles and a spider that live within ant colonies.

Predator MimicryThis is different from aggressive mimicry because it is

mimicry of, not by, a predator. In some cases prey may

avoid predation by mimicking the predator or young of the

predator. In other words, it is a “sheep in wolf’s clothing.”

For example, Japanese tetra have eyespots on their tails

that mimic the young of predaceous Central American

Cichlids.

Some species of Passiflora (passion vine) have leaf spots

or stipules that mimic the eggs of Helioconius butterfly

eggs. They avoid oviposition by butterflies who are fooled

by the appearance that eggs are already there.

Review: Adaptive Coloration

crypsis

eucrypsis

homochromy

transparency

disruptive coloration

countershading

protective resemblance - mimesis

bizarre pattern/shape

pseudocephalism

shock pattern

aposematism

mimicry

Batesian mimicry – pseudaposematism

behavioral Batesian mimicry, automimicry

Mullerian mimicry – synaposematism

Mertensian mimicry - XAggressive mimicry – Peckhamian mimicry

exploiter resembles prey, exploiter resembles helpful species, exploiter

resembles harmless species, exploiter resembles edible species, auditory

mimicry, olfactory mimicry, pseudocopulation, photomimicry

Wasmannian mimicry

Predator mimicry

The mimic octopus is known to mimic a variety of other animals.

Here you can see it looking like a flounder, a lion fish, and a sea snake. How many different types of mimicry do you think are involved?

adaptive coloration - auburn university

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