part 5 mimicry and tricks
Terms in this set (20)
adaptations that involve deceptions or tricks
deception by prey for their own defense
deception by predators to help catch prey
types of deception: crypsis
defense strategy for palatable prey, prey organisms that are good to eat
a way for prey to camouflage to mimic their background, or to look like something that is not good to eat
aspects of adaptation that requires the appropriate appearance and phenotypes to have the appropriate shape or color. also requires behavioral adaptations, organism must choose right background and have the right movements. both form and behavior are involved
example of crypsis (insects): peruvian katydid
it resembles a dead leaf, these insects move very slowly during the day. dead leafs are a very common background habitat especially in the tropics. leaves are something that predators don't eat. a number of species have evolved to mimic leaves, turned out to be quite a important convergence.
insects have also evolved to mimic sticks, must have the right color, shape, and behavior. stick insects are another kind of mimicry that has evolved in a number on insects.
leave mimicry is also involved in a few vertebrates: south american frog.
example: vertebrate crypsis: eurasian bittern, flounder
bird that nests in reeds. when it stays on the nest, the stripes along its nest move with the reeds. so it blends into its background, and does it when its alarmed.
flounder: ability to achieve crypsis in all different kinds of background. as part of its development it has two eyes on the side of its head. it changes color to match whatever sub straight they're on
south american sloth
there are six species of this kind of mammal, large species that live in trees. have symbiotic bacteria in their gut that breaks down this tough leaves. the leaves are low energy food, so they have very low metabolic rates and move very slowly.
photosynthetic bacteria live in their fur, green algae. it multiplies during the wet season, and the animals looks green. in the dry season, the natural brown color returns and the sloth blends into the dryer leaves
types of deception 2: startle and bluff strategies
defense strategy for palatable prey. strategy for organisms that are good to eat. a way for tasty prey to use deception to scare off predators.
example of startle and bluff: blue tailed skink
has a bright colored tail, and if its attacked it can jettison the tail, let it go. when it lets the tail go, the muscles continue to move and the tail thrashes around. the predator is fascinated by the tail while the skink gets away. when a skink automatizes its tail, it can later regrow a new tail. but it does not have vertebrae but a cartilaginous rod.
pigmentation to look like eyespots
example: larva of a butterfly. the idea of the eyespots is to make a defensive animal like a caterpillar to look like a big animals like an owl or snake. this butterfly larvae has this imitation. the eyes give the illusion that its looking at you, very startling.
moth larva, evolved eyespots to look like a snake. and the thorax inflates to look like a snake head. pigmentation spots have evolved to look just like reflection on the eyeball, becoming selectively favored over evolution.
adult insects with eyespots
many animals have converged on 'eyespot' coloration to mimic the face of a large predator
also frogs have evolved this.
types of deception 3: aggressive crypsis
camouflage to sneak up on prey. involves phenotypic matching and the right behavior.
south american leaf fishes imitate dead leaves. they float in water until a smaller prey item comes by to which they eat it.
frogfish has a cryptic body and a lure to attract smaller fish. hang around the bottom of the sea, the fish mimics a rock covered with algae, its motionless while it has a lure in front of its mouth. when something comes along to eat the lure, the frogfish eats the prey instead.
terrestrial crypsis involving flowers
good place to catch and eat insects. spiders especially have evolved to do crypsis on flowers. evolved coloration to match many different types of flower species. crab spiders: find a flower that matches coloration and stay motionless in the flower for days or weeks. when an insect pollinator comes, the spider grabs them with their strong legs and eats them
flower mantids: evolved beautiful colors to be able to hide in flowers.
an african flower mantis chooses different backgrounds at different life cycle stages. changes color throughout lifetime.
types of deception 4: aposematic coloration
to warn potential predators. prey animals that have evolved some kind of chemical or physical defense (toxins or ability to sting), might advertise that it is nasty to eat to predators. instead of hiding, or bluffing to predators, many animals that have these toxic or stinging properties have evolved aposematic coloration, a way of advertise who you are.
example: south american tree frogs have poisonous skin secretions and have evolved aposematic coloration to warn predators not to eat them. involves red, black, and yellow coloration. contrasting colors against natural backdrops. also involves spots or stripes, patterns that stand out.
aposematic coloration has evolved in many different organisms: snakes, moths, wasps, newt, millipedes. all animals that have a defense and advertise that they are not good to eat, all have converged on red, black, and yellow patterns.
use of multiple types of deception
alder moth caterpillars as larvae looks like bird droppings (crypsis). as it eats and grows it stores toxins within its body and evolves aposematic coloration to warn predators that its toxic.
how do aposematic phenotypes evolve
when eating the animal doesnt kill the predator. it has to do with learning. predator must learn from experience, eat a couple of prey that makes it sick. so it then associates the appearance to the nasty experience of eating it.
selection on the prey items promote having more recognized phenotypes. and selection on the predator allows it to learn to avoid that species. coevolution that supports both predator and its avoidance of the prey and the prey's ability to be recognized. for the predator to learn, it has to try to eat one. so some are sacrificed by the predator's trial and error. creating a type of selection pressure to converge on an aposematic pattern
different poisonous species in one ecological community may converge on a similar aposematic color or pattern
in order to benefit a predator's learning curve. they are spreading around the sacrifice of educating the predators.
this convergence works as long as all the prey species are toxic, so they will all reinforce the predator's learned avoidance.
phenotype resemblance of one species to another, unrelated species
several toxic species evolve to resemble each other. benefitting from the fact that the predators will learn to avoid them
monarch butterfly: larvae eat milkweed plants that contain defense alkaloids. these chemicals affect the vertebrate heartbeat, poisonous to small animals. instead of being hurt, the larvae stores the toxins within its body. so the larva is toxic and have an aposematic coloration. as an adult, the butterfly is still toxic and has a coloration to warn predators.
selective advantage of monarchs to have a selectively bright phenotypes and there is an advantage for all the monarchs to resemble each other because all the monarchs will have benefitted from a predators eating one that looks like it. so very few individuals of the species have to be sacrificed because the bird learns to avoid anything that looks like a monarch
a palatable/ nontoxic species gains protection by resembling a toxic species. there must be a model species, with the phenotype that is being imitated.
the mimic species is the species that is edible, and does not have its own defense mechanisms so it copies a species that has a defense. the mimic benefits from the fact that the predator has learned to avoid the model.
the viceroy butterfly, occurs in the same habitat as the monarch and has evolve to look like the monarch. birds have learned to avoid the model and therefore will also avoid the mimic.
BUT: the mimic species must be less common than the model. because if a bird eats the viceroy and is fine, it will learn that this phenotype is actually very good to eat. and then that phenotype no longer works. so the predators must learn from eating the models.
if there is a population with more viceroys and birds are eating them and monarchs. natural selection will favor the monarchs that look different, pushing the phenotypes to become different and the mimicry system would break down.
batesian mimicry is very widespread in nature
evolved in species of snakes, bird, fish, snails. defenseless uncommon species have evolved to look like toxic species.
some beetles and flies have evolved to mimic wasps.
scenario involving deceit
arabis plant grows in alpine habitats. produces white petals, able to self fertilize. these plants get infected by puccinia fungus, which grows into the plants tissues in the winter. in the spring instead of producing flowers, the fungus takes over its developmental system it produces a cluster of leaves that are covered with fungal reproductive organs that are bright yellow. sudo flowers, fake flowers; they also exude a sticky substance and smell like flowers, mimicking the buttercups in its habitat. as a result, insects that usually visit the buttercups visit the sudo flowers, spreading the fungal spores from one plant to another.