Instruction 6-7 Biodiversity | Ecosystem Changes | Fluctuation in Population Size | Water, Carbon and Nitrogen Cycle | Stability in an Ecosystem | Energy Pyramid | Accommodation and Adaptation
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| Accommodation and Adaptation | ||
| CA GR.9-12 6.g. | ||
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Accommodation There is a species of ant that builds nests made of leaves. To build a nest, some of these ants pull the edges of two leaves together and hold them in place, while others carry larva in their jaws and 'sew' them together with the silk they secrete. This is certainly a complex feat of engineering. This behavior is instinctive, built into the ants' behavior mechanisms. They cannot alter their plans or think of better ways to join leaves. They cannot teach or be taught to do so. If their environment changed in a way that they can no longer survive, they would then have to physically adapt or cease to exist - extinction. But there are examples of animals that can accommodate, such as dogs. Dogs were wild at one time, and have become domesticated. A dog does not know instinctively not to urinate or defecate indoors, but it can be taught not to do so. Dogs are capable of learning specific behaviors. If you were to take a dog that has learned not to eliminate indoors to a different house, it would still know not to eliminate there. This is because the dog has made a generalization about his environment, it knows not to urinate or defecate in any house, not just the one in which it was taught, it has changed his behavior and accommodated to its surroundings. Another example is scientists wanted to learn about eating behaviors in Macaque monkeys, so they put some sweet potatoes on a beach near where they lived. The sweet potatoes got sandy and, as the monkeys disliked dirty food, they would spend some time picking the sand off. One young female, however started taking her potatoes to a freshwater pool to rinse off. She showed the others how to do so as well. The scientists then threw wheat on the sand, hoping the monkeys would spend more time picking the food out so they would have more time to observe them. The same young female just scooped up handfuls of wheat and sand and dumped them in the water. The sand sank and the wheat floated, which she ate. This practice also quickly spread through the group. This is what we could call a learned behavior. By the desire to obtain food and eat, it has changed its behavior to get the food and had to accommodate in order to eat the food to survive. Adaptation Animal Adaptations In order for animals to survive, they need to be able to adapt. In this part of the lesson, we will look at the types of adaptations animals can and do make. In a perfect world, animals would not need to adapt. However, with constant changes to their environment, food chain and climate, animals must adapt or face extinction. There are many examples of animals facing extinction. Later on in the course, we will take a look at some of these examples, and the reasons for their endangerment. Adaptation An adaptation is a trait that makes an animal suited to its environment. It can be a behavioral or a structural trait. Here are some examples:
Adaptation happens over a long period of time. Structural adaptation happens in the form of changing an animal’s genetic traits. Take for example this imaginary animal, the whatsit. The whatsit lives in woods. It s hunted by men and larger animals. Most whatsits are born with white fur, making them easy to spot amongst the trees. Some whatsits are born with brown, speckled fur. These are far more difficult to spot. Since they are easier targets for hunters, far more white whatsits are hunted and killed than speckled ones. Each time a speckled one mates with a white one, half the offspring are speckled. Eventually the amount of white furred ones available to breed is smaller than the number of speckled ones. More offspring are born with speckles than with white fur. This animal has adapted, and now the majority has speckled fur instead of white fur. Eventually the white furred ones will disappear altogether. There are many examples of this type of adaptation. Because it happens over generations, it is slow. In some cases, the inability of animals to adapt quickly enough have led to their being threatened or extinction. Behavioral adaptation can happen far more quickly. The more intelligent an animal is the faster it can learn to make behavioral changes, in order to survive. If you take the most intelligent of animals, you can understand what happens. Humans adapt in many ways in order to survive. Here is an imaginary example of human adaptation: A group of people lives in village Somewhere. In the village, a large number of children die each year, after being attacked by wild animals. The villagers can make changes to their environment and behavior in order to protect the children. They can build fences around the village. They can make traps to catch the animals. They can ensure that the children only go out in groups, protected by armed adults. All of these are behavioral changes, and can happen almost overnight. The speed with which they happen depends on the intelligence of the animals and their ability to work as a community. Adaptation can work in two ways. The best example of this is camouflage. A chameleon can change its color according to its surroundings. Think about how this helps protect it. Not only does it help protect the chameleon, it also helps it survive in another way. Because it blends in so well with its surroundings, insects are less likely to see or notice it. By blending in it also makes it a better hunter, it can hunt without being seen, In fact, it is such an efficient adaptation that hunting is probably the wrong word o use. It just blends in and patiently sits waiting for some unsuspecting insect to happen along. Then, flick, out goes the tongue and there is one less insect and one less hungry chameleon. The more ways a single adaptation helps an animal to survive, the better it is. Going back to the arctic fox and its fur coat. How can that coat help the fox in more than one way? The answer lies in the color of the coat. Obviously, in a landscape covered in snow, a thick, white coat is very useful. This adaptation works in three ways. It protects the fox from the cold ad provides camouflage. The camouflage allows it to hunt more efficiently and hide from would-be predators. All animals live in habitats. Habitats provide food, water, and shelter, which animals need to survive, but there is more to survival than just the habitat. Animals also depend on their physical features to help them obtain food, keep safe, build homes, withstand weather, and attract mates. These physical features are called physical adaptations. Physical adaptations, like we said, do not develop during an animal's life but over many generations. The shape of a bird's beak, the numbers of fingers, color of the fur, the thickness or thinness of the fur, the shape of the nose or ears are all examples of physical adaptations, which help different animals to survive. Anything that helps an organism survive in its environment is an adaptation. It also refers to the ability of living things to adjust to different conditions within their environments. These are a few different types of adaptations that occur in nature.
A structural adaptation involves some part of an animal's body, such as
the size or shape of the teeth, the animal's body covering, or the way
the animal moves.
Camouflage is like mimicry except instead of looking like another animal the look like there surroundings and are adaptations some animals use as protection from predators. An animal that uses camouflage looks like things in its environment. It might look like a leaf, a twig, or a rock. Animals that use mimicry use colors and markings to look like another animal. Cryptic Katydids Katydids camouflage to a wide variety of environments. Can you find the katydid in each picture?
Behavior adaptations include activities that help an animal survive.
Behavior adaptations can be learned or instinctive and is a behavior an
animal is born with. Migration is the behavioral adaptation that involves an animal or group
of animals moving from one region to another and then back again.
Hibernation is a deep sleep in which an animal's body temperature drops Animals that hibernate are
During the hibernation, the animals live off the fat that is stored in their body. Plant Adaptations Have you ever wondered how a cactus can grow in the desert? Or plants
can grow in the ocean without much sunlight? Or even how a plant happens
to grow in an area without being planted or having another one like it
nearby? Water-limited Adaptations – Many plants live in what you would call a
water-limited environment. This means they live in environments where
water is scarce or hard to come by, like in a desert. In order for a
plant to survive in such an environment, it must have adaptations to
help them cope with the lack of water. Many desert and arid plants have
evolved ways to capture and store water so that during the rare times
when it rains in the desert, they can take up as much water as possible
and store some for later.
Cactuses, many palms, agaves and euphorbs (cactus-like desert plants) do this. These plants will store water in their stems, leaves or trunks. We call these “succulent” stems or leaves. Many of these plants also keep their stomata closed during the day to prevent too much water loss in the hot dry sun and open them instead at night.
Many orchids and bromeliads have ways to capture and store water as well. Such orchids and bromeliads often grow in tropical rainforests, so why do they need to store water if there is plenty of rain? These plants live on the bark of other trees, thus they do not have access to the wet soil and need ways to capture and store water for themselves when it rains.
Adaptations for light limited environments – Some plants live in what
you would call a light-limited environment. That means that light is
very scarce or hard to come by. This is what occurs in most dense
forests, since very little light gets through the forest canopy. If you
are a plant on the floor of a thick forest, you will not receive very
much light during the day. So, many plants that grow in thick tropical
rainforests have adaptations that allow them to get more light so they
can maximize photosynthesis and survive.
Many plants have adaptations for climbing, so that they can climb up closer to the top of the canopy where there is more light. These include vines and lianas (which are woody vines). Epiphytes like orchids and bromeliads have adapted to live in canopy trees where there is more light. Plants that spend their lives on the forest floor often have dark green leaves with red undersides. This coloration helps them capture the most light that they can from the shady forest floor. The dark green indicates an abundance of chlorophyll and the red serves to reflect light back into the leaf so it is not lost. If you hold one of these leaves up to the light, you will notice that very little light gets through. Many of these plants are so well adapted to dim light that they do not
do well if exposed to full sunlight. Other plants have adapted to remain
small for long periods of time, then to grow quickly when a canopy tree
falls and lets more light through.
Supportive adaptations – plants have numerous structural adaptations for support. These are the easiest adaptations to observe. For instance, some tropical trees have buttress roots, which are roots that come out from the lower part of the trunk and grow into the ground, providing support for the tree. Prop roots are another supportive root structure that you may know from looking at red mangroves. Some trees grow in very unstable soil, and the complex prop root system helps keep the tree stable in an unstable environment. Epiphytes and vines also have special roots that help them grab onto a tree’s bark and stay put.
Defensive adaptations - Plants also need to be able to defend themselves against predators in order to survive. Therefore, defensive adaptations also fall in this category of functional adaptation. Plants as we know have evolved ways to defend themselves by using sharp spines, thorns or hairs: cellulose that makes them hard to digest, or creating toxic chemicals. Another unusual way some plants have evolved to defend themselves is through mimicry - that is they evolve to look like another plant that is poisonous and animals are fooled into believing that they are poisonous. So, the plant does not get eaten and does not have to waste energy producing a poison or other defense mechanism. It makes sense that through natural selection, those plants that look more like real poisonous plants would survive to pass on their genes while others would get eaten. This is how mimicry occurs. Note that some animals use mimicry as well. Reproductive Adaptations You are a plant that has all the appropriate adaptations to survive and defend yourself in your environment, is that enough to ensure survival of your species? Not really, now you must also reproduce. Plants that have flowers (angiosperms) have many adaptations that allow them to successfully reproduce. We know that flowers that depend on wind pollination often have small unimpressive flowers since they do not need to attract a pollinator. In addition to pollination, flowers have developed a number of other adaptations to help them reproduce successfully and prevent self-fertilization. These are some other reproductive adaptations and strategies: Annual adaptations - Some plants grow quickly within one year, produce lots and lots of seeds all at once and then die. We call these plants annuals. Many of our crops, like corn and wheat, are annuals. Annuals are almost always herbs. Because they live short lives, they do not have time to invest in making wood, but simply grow as much as possible in a year then reproduce and die. The benefit to this is that a plant is able to invest all its energy into reproduction, because it is investing minimal energy into long-term survival. Perennial adaptations – other plants will live for years and years, and reproduce over many seasons. These plants will generally have fewer seeds per season than annual plants, but they reproduce many times over their lifespan. Perennials can be trees, shrubs or herbs. Self-fertilization prevention - flowers have a number of adaptations to limit self-fertilization. Some flowers are self-incompatible, meaning that the female part (carpel) will not accept its own pollen. Other flowers are dioecious, dicot, (having separate male and female individuals) which makes self-fertilization impossible. Some are monoecious, monocot, (having separate male and female flowers on the same plant) and their male and female flowers will mature at different times. Some flowers will make their stigma receptive to pollen only after all of its pollen has been shed. Some flowers keep their stamens, carpel at a distance from each other, for instance, the carpel may be very tall, and the stamens may be short, making it harder for the flower to pollinate itself. More Examples of Plant Adaptations The growth point of grasses is at the base of the plant rather that at the tips of branches as in most plants. Specialized leaves of tropical plants often are the homes of ants; the ants raise aphids on the plant (aphids are insects that produce sugar as a by-product) and attack any grazing animal who might disturb the plant. The fruits of the persimmon are readily edible by numerous animals late in the season when the seed is fully mature; prior to that, the fruit is highly sharp or sour tasting. Petal coloring in the flowers is used throughout the plant world is used frequently for adaptations. Different flower colors attract different classes of pollinators; red-flowered Indian paintbrushes tend to be visited by butterflies and hummingbirds whereas those with brownish-yellow flowers tend to be visited by bees and ants. Strawberries have underground stems ("stolons") which readily break so that a new plant can result from just a portion of the parent plant (asexual reproduction). Leaves of desert plants are often hairy (to reduce water loss) whereas those in the tropics are mostly smooth; likewise fruits in temperate. regions tend to be hard (nuts, acorns) whereas those of the tropics are often fleshy (banana). Flowers tend to be large and solitary in tropical plants; smaller and
more numerous in temperate regions. Five experiments you can do with plants try and have fun and change
things around to see if you can get different results.
Now let's do Practice Exercise 6-7 (top). |
to about the temperature of the environment. Body activities, such as
heartbeat and breathing are slowed causing the animal to need very
little food. 
