Download adaptive coloration

adaptive coloration
concealment,
advertisement,
and disguise
crypsis, etc.
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
“transparency”
glasswinged butterfly
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 mimesis
when an organism looks like something else in its environment
sargassum fish
in Sargassum
protective resemblance
protective resemblance
Lithops, stone plant
protective resemblance (mimesis)
Behavior may play an important part in crypsis.
broken-twig moth
katydid
dead-leaf butterfly
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.
rubber boa
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.
Pseudocephalism
The Io moth has more than one “trick up its sleeve.”
shock patterns
False eyes or other patterns
may produce a startle effect
when revealed suddenly.
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
mimic spider
model lady beetle
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.)
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.
olfactory Batesian mimicry has been proposed for stink bugs,
some of which taste bad and others that do not.
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?
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 Mimicry
Also 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.
Lycorea sp.
Helioconus spp.
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.
X
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.
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
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.
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.
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
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.
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.
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
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 Mimicry
Sometimes 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 mimicry
Exploiter 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.
Aggressive mimicry con’t
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.
Mastophora hutchinsoni
Drakea livida
Aggressive mimicry con’t
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.
Aggressive mimicry con’t
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 homemaker. Here are darkling beetles and a spider
that live within ant colonies.
Predator Mimicry
This 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 - X
Aggressive 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?