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The Organization of Life

98 Chapter 4 The Organization of Life

C H A P T E R 41 Ecosystems: Everything

Is Connected

2 Evolution

3 The Diversity of LivingThings

PRE-READING ACTIVITY

LayeredBookBefore youread this

chapter, create the FoldNoteentitled “Layered Book”described in the Reading andStudy Skills section of theAppendix. Label the tabs ofthe layered book with“Ecosystem,” “Population,”“Community,” and“Habitat.” As you read thechapter, write informationyou learn about each category undertheappro-priateflap.

A coral reef is an ecosystem thatcontains a wide variety of species.How many different species can youfind in this photograph?

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Section 1 Ecosystems: Everything Is Connected 99

You may have heard the concept that in nature everything isconnected. What does this mean? Consider the following example.In 1995, scientists interested in controlling gypsy moths, whichkill oak trees, performed an experiment. The scientists removedmost mice, which eat young gypsy moths, from selected plots ofoak forest. The number of gypsy moth eggs and young increaseddramatically. The scientists then added acorns to the plots. Miceeat acorns. The number of mice soon increased, and the numberof gypsy moths declined as the mice ate them as well.

This result showed that large acorn crops can suppress gypsymoth outbreaks. Interestingly, the acorns also attracted deer,which carry parasitic insects called ticks. Young ticks sooninfested the mice. Wild mice carry the organism that causes Lymedisease. Ticks can pick up the organism when they bite mice.Then the ticks can bite and infect humans. This example showsthat in nature, things that we would never think are connected—mice, acorns, ticks, and a human disease—can be linked to eachother in a complex web.

Defining an EcosystemThe mice, moths, oak trees, deer, and ticks in the previous exampleare all part of the same ecosystem. An (EE koh SIS tuhm)is all of the organisms living in an area together with their physicalenvironment. An oak forest is an ecosystem. The coral reef onthe opposite page is an ecosystem. Even a vacant lot, as shownin Figure 1, is an ecosystem.

ecosystem

Objectives� Distinguish between the biotic and

abiotic factors in an ecosystem.� Describe how a population differs

from a species.� Explain how habitats are impor-

tant for organisms.

Key Termsecosystembiotic factorabiotic factororganismspeciespopulationcommunityhabitat

S E C T I O N 1

Ecosystems: Everything Is Connected

Figure 1 � This vacant lot is actuallya small ecosystem. It includes variousorganisms, including plants andinsects, as well as soil, air, and sunlight.

www.scilinks.orgTopic: EcosystemsCode: HE80466

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Ecosystems Are Connected People often think of ecosystems asisolated from each other, but ecosystems do not have clearboundaries. Things move from one ecosystem into another. Soilwashes from a mountain into a lake, birds migrate from Michiganto Mexico, and pollen blows from a forest into a field.

The Components of an EcosystemIn order to survive, ecosystems need certain basic components. These are energy, mineral nutrients, carbon dioxide, water, oxy-gen, and living organisms. As shown in Figure 2, plants and soilare two of the most obvious components of most land ecosys-tems. The energy in most ecosystems comes from the sun.

To appreciate how all of the things in an ecosystem are con-nected, think about how a car works. The engine alone is madeup of hundreds of parts that all work together. If even one partbreaks, the car might not run. Likewise, if one part of an ecosys-tem is destroyed or changes, the entire system may be affected.

Biotic and Abiotic Factors An ecosystem is made up of bothliving and nonliving things. are the living and onceliving parts of an ecosystem, including all of the plants and animals.Biotic factors include dead organisms, dead parts of organisms,such as leaves, and the organisms’ waste products. (ay bieAHT ik) are the nonliving parts of the ecosystem. Abioticfactors include air, water, rocks, sand, light, and temperature.Figure 3 shows several biotic and abiotic factors in an Alaskanecosystem.

Scientists organize living things into levels. Figure 4 showshow an ecosystem fits into the organization of living things.

What is the difference between a biotic factor andan abiotic factor? (See the Appendix for answers to Reading Checks.)■●✓ Reading Check

factorsAbiotic

Biotic factors


Figure 2 � Like all ecosystems, thiscoastal region in France contains certain basic components. Whatcomponents can you identify?

Figure 3 � This caribou is a bioticfactor in a cold, northern ecosystemin Denali National Park, Alaska.

GeofactThe Living Soil Soil, which is partof nearly all ecosystems on land, isformed in part by living organisms,which break down dead leaves andorganisms. Small, plantlike organ-isms even help break down rocks!

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Organisms An is an individual living thing. You are anorganism, as is an ant crawling across the floor, an ivy plant onthe windowsill, and a bacterium in your intestines.

A is a group of organisms that can mate to producefertile offspring. All humans, for example, are members of thespecies Homo sapiens, while all black widow spiders are mem-bers of the species Latrodectus mactans. Every organism is amember of a species.

Populations Members of a species may not all live in the sameplace. Field mice in Maine and field mice in Florida will neverinteract even though they are members of the same species. Anorganism lives as part of a population. A is all themembers of the same species that live in the same place at thesame time. For example, all the field mice in a corn field makeup one population of field mice.

An important characteristic of a population is that its membersusually breed with one another rather than with members ofother populations. The bison in Figure 5 (right) will usually mate with another member of the same herd,just as the wildflowers (left) will usually bepollinated by other flowers in the same field.

population

species

organism

Figure 4 � An individual organism ispart of a population, a community,an ecosystem, and the biosphere.

Section 1 Ecosystems: Everything Is Connected 101

Figure 5 � Two of the populationsshown here are a population of purple-flowered musk thistle (left) and a herdof bison (right).

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1. List the abiotic and biotic factors you see in thenorthern ecosystem in Figure 3.

2. Describe a population not mentioned in this section.

3. Describe which factors of an ecosystem are not partof a community.

4. Explain the difference between a population and aspecies.

CRITICAL THINKING5. Analyzing Relationships Write your own defini-

tion of the term community, using the terms bioticfactors and abiotic factors.

6. Understanding Concepts Why might a scientistsay that an animal is becoming rare because ofhabitat destruction?

WRITING SKILLS

S E C T I O N 1 Review

Communities Every population is part of a a groupof various species that live in the same place and interact witheach other. A community is different from an ecosystem because acommunity is made up only of biotic components. A pond commu-nity, for example, includes all of the populations of plants, fish,and insects that live in and around the pond. All of the livingthings in an ecosystem belong to one or more communities.

Communities differ in the types and numbers of species theyhave. A land community is often characterized by the types ofplants that are dominant. These plants determine the other organ-isms that can live in this community. For example, the dominantplant in a Colorado forest might be its ponderosa pine trees. Thispine community will have animals, such as squirrels, that live inand feed on these trees.

HabitatThe squirrels mentioned above live in apine forest. All organisms live in particularplaces. The place an organism lives is calledits A howler monkey’s habitat isthe rain forest and a cactus’s habitat is adesert. The salamander shown in Figure 6 isin its natural habitat, the damp forest floor.

Every habitat has specific biotic and abi-otic factors that the organisms living thereneed to survive. A coral reef contains seawater, coral, sunlight, and a wide variety ofother organisms. If any of these factorschange, then the habitat changes.

Organisms tend to be very well suited totheir natural habitats. Indeed, animals andplants cannot usually survive for long peri-

ods of time away from their natural habitats. For example, a fishthat lives in the crevices of a coral reef will die if the coral reef isdestroyed.

Why is an organism’s habitat important for thatorganism? (See the Appendix for answers to Reading Checks.)■●✓ Reading Check

habitat.

community,

Figure 6 � Salamanders, such as thisred-backed salamander, live in habi-tats that are moist and shaded.

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Organisms tend to be well suited to where they live and what theydo. Figure 7 shows a chameleon (kuh MEEL ee uhn) capturing aninsect. Insects are not easy to catch, so how does the chameleon doit? Chameleons can change the color and pattern of their skin, andthen blend into their backgrounds. Their eyes are raised on little,mobile turrets that enable the lizards to look around without mov-ing. An insect is unlikely to notice such an animal sitting motionlesson a branch. When the insect moves within range, the chameleonshoots out an amazingly long tongue to grab the insect.

Evolution by Natural SelectionIn 1859, English naturalist Charles Darwin observed that organ-isms in a population differ slightly from each other in form, function, and behavior. Some of these differences are hereditary(huh RED i TER ee)—that is, passed from parent to offspring.Darwin proposed that the environment exerts a strong influenceover which individuals survive to produce offspring. Some indi-viduals, because of certain traits, are more likely to survive andreproduce than other individuals. Darwin used the term

to describe the survival and reproduction of organismswith particular traits.

Darwin proposed that over many generations natural selectioncauses the characteristics of populations to change. A change inthe genetic characteristics of a population from one generation tothe next is known as

How is natural selection related to the process ofevolution?■●✓ Reading Check

evolution.

selectionnatural

Objectives� Explain the process of evolution by

natural selection.� Explain the concept of adaptation.� Describe the steps by which a

population of insects becomesresistant to a pesticide.

Key Termsnatural selection evolutionadaptationartificial selectionresistance

S E C T I O N 2

Evolution

GeologyConnection to

Darwin and Fossils In the1800s, fossil hunting was a popu-lar hobby. The many fossils thatpeople found started argumentsabout where fossils come from.Darwin’s theory of evolution pro-posed that fossils are the remainsof extinct species from whichmodern species evolved. When hisbook on the theory of evolutionwas first published in 1859, itbecame an immediate bestseller.

Figure 7 � A chameleon catches anunsuspecting insect that has strayedwithin range of the lizard’s long, fast-moving tongue.

Section 2 Evolution 103

www.scilinks.orgTopic: EvolutionCode: HE80546

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Nature Selects Darwin thought that nature selects for certaintraits, such as sharper claws or lighter feathers, because organismswith these traits are more likely to survive and reproduce. Forexample, lions that have the trait of sharper claws can kill theirprey more easily than lions with duller claws. Thus, lions withsharper claws are more likely to survive and reproduce. Over time,the lion population includes a greater and greater proportion oflions with sharper claws. As the populations of a given specieschange, so does the species. Table 1 summarizes the premises ofDarwin’s theory of evolution by natural selection. Darwin proposedhis theory after drawing a conclusion based on these premises.


Evolution by Natural Selection

Premises Conclusion

1. Individuals in a population vary in each generation.

2. Some of these variations are genetic, or inherited.

3. More individuals are produced than live to grow up andreproduce.

4. Individuals with some genes are more likely to survive and reproduce than individuals with other genes.

Table 1 �

Darwin’s Finches

Before Charles Darwin formulatedhis theory of evolution, he sailedaround the coast of South America.The plants and animals he saw had agreat effect on his thinking abouthow modern organisms had origi-nated. He was surprised by theorganisms he saw on islands becausethey were often unusual speciesfound nowhere else.

He was particularly impressed by the organisms in the GalápagosIslands, an isolated group of volcanicislands in the Pacific Ocean west ofEcuador. The islands contain 13unique species of birds, which havebecome known as Darwin’s finches.All the species look generally similar,

Princeton University biologistsPeter and Rosemary Grant havespent 25 years studying Darwin’sfinches on Daphne Major, one ofthe Galápagos Islands. Here, one

but different species have differentlyspecialized bills adapted to eatingdifferent types of food. Some specieshave large, parrotlike bills adapted tocracking big seeds, some specieshave slim bills that are used to sipnectar from flowers, and somespecies have even become insecteaters. Darwin speculated that allthe Galápagos finches had evolvedfrom a single species of seed-eatingfinch that found its way to theislands from the South Americanmainland. Populations of the finchesbecame established on the variousislands, and the finches that survivedwere those able to eat what theyfound on their island.

� Notice the beaks in the twospecies of Darwin’s finches. Whatdo you think these finches eat?

Based on these four premises, individualswith genetic traits that make them morelikely to grow up and reproduce in theexisting environment will become morecommon in the population from onegeneration to the next.

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Figure 8 shows an example of evolution in which a population ofdeer become isolated in a cold area. Many die, but some have genesfor thicker, warmer fur. These deer are more likely to survive, andtheir young with thick fur are also more likely to survive to repro-duce. The deer’s thick fur is an an inherited trait thatincreases an organism’s chance of survival and reproduction in acertain environment.

adaptation,


These deer live in a warm climate. Some have thicker fur than others.

Some deer become separated from the rest of the group.

In the cold mountain climate, deer with thicker fur are more likely to survive.

As years pass, eachgeneration has agreater proportionof deer with thick fur. After many generations, most deer have thick fur.

Figure 8 � These steps show the evolution of thicker fur in a population of deer.

species, the medium ground finch,has a short, stubby beak and eatsseeds as well as a few insects. Theground finches have few predators.The Grants found that the main fac-tor that determined whether a finchlived or died was how much foodwas available. During a longdrought in 1977, many plants diedand the small seeds that the finches

food source. Second, shifts in rain-fall determine which plants live anddie, further limiting the finches’food sources.

The islands are strongly influ-enced by El Niño and La Niñaweather patterns. These weatherpatterns produce alternating peri-ods of very wet and very dryweather in a relatively short time.The plants vary, depending on theweather pattern, exerting differentselective pressures on the animalsthat depend on the plants for food.

CRITICAL THINKING

1. Analyzing RelationshipsCould the finches that evolvedbigger beaks in this study evolvesmaller beaks some day?

eat became scarce. Only finchesthat had large beaks survived. Largebeaks allowed them to eat largerseeds from the larger plants thathad survived the drought.

The finches that survived thedrought passed their genes forlarge beaks to their offspring. Twoyears later, the Grants found thatthe beaks of medium groundfinches on Daphne Major werenearly 4 percent larger, on aver-age, than they had been beforethe drought. The Grants hadobserved evolution occurring inbirds over a short period of time,something that had seldom beenseen before.

Two factors make the GalápagosIslands well suited for researchingevolution. First, there are few plantspecies in the community, so thefinches have little choice in their

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Coevolution Organisms evolve adaptations to other organisms and to their physical environment. The process of two species

evolving in response to long-term interactions with each otheris called coevolution (koh EV uh LOO shuhn). One possibleexample is shown in Figure 9. The honeycreeper’s beak islong and curved, which lets it reach the nectar at the baseof the long, curved flower. The flower has evolved struc-tures that cause the bird to get pollen on its head as it sips

the nectar. When the bird moves to another flower, some ofthe pollen rubs off. In this way, the bird helps lobelia plants

reproduce. The honeycreeper’s adaptation for obtaining morenectar is a long, curved beak. The plant has two adaptations for

greater pollination. One is sweet nectar, which attracts the birds.The other is a flower structure that forces pollen onto a bird’s headwhen the bird sips the nectar.

Evolution by Artificial SelectionMany populations of plants and animals do not live in the wildbut are cared for by humans. People control how these organismsreproduce and therefore how they evolve. The two species inFigure 10 are closely related. Over thousands of years, humansbred the ancestors of today’s wolves to produce the variety of dog breeds. The selective breeding of organisms by humans forspecific characteristics is called

The fruits, grains, and vegetables we eat were also producedby artificial selection. By selecting for traits such as size andsweetness, farmers directed the evolution of crop plants. As aresult, crops produce fruits, grains, and roots that are larger,sweeter, and easier to harvest than their wild relatives. NativeAmericans cultivated the ancestor of today’s corn from a grasslikeplant in the mountains of Mexico. Modern corn is very differentfrom the wild plant that was its ancestor.

How is artificial selection different from naturalselection?■●✓ Reading Check

artificial selection.


MATHPRACTICEPlumper PumpkinsEach year a farmer saves and plants only the seeds from his largest pumpkins. Suppose thathe starts with pumpkins that average5 kg and each year grows pumpkinsthat are 3 percent more massive, onaverage, than those he grew the yearbefore. What will be the averagemass of his pumpkins after 10 years?

Figure 10 � As a result of artificialselection, the Chihuahua on the rightlooks very different from its wolfancestor on the left.

Figure 9 � This Hawaiian honey-creeper is using its curved beak to sipnectar from a lobelia flower.

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Evolution of ResistanceSometimes humans cause populations of organisms to evolveunwanted adaptations. You may have heard about insect peststhat are resistant to pesticides and about bacteria that are resist-ant to antibiotics. What is resistance, and what does it have todo with evolution?

is the ability of one or more organisms to toleratea particular chemical designed to kill it. An organism may beresistant to a chemical when it contains a gene that allows it tobreak the chemical down into harmless substances. By trying tocontrol pests and bacteria with chemicals, humans promote theevolution of resistant populations.

Pesticide Resistance Consider the evolution of pesticideresistance among corn pests, as shown in Figure 11. A pesticideis sprayed on corn to kill grasshoppers. Most of the grasshop-pers die, but a few survive. The survivors happen to have a ver-sion of a gene that protects them from the pesticide. Thesurviving insects pass on the gene to their offspring. Each timethe corn is sprayed, insects that are resistant to the pesticidewill have a greater chance of survival and reproduction. As aresult, the insect population will evolve to include more andmore resistant members.

Resistance


1. Explain what an adaptation is, and provide threeexamples.

2. Explain the process of evolution by natural selection.

3. Describe one way in which artificial selection canbenefit humans.

4. Explain how a population of insects could becomeresistant to a pesticide.

CRITICAL THINKING5. Understanding Concepts Read the description of

evolution by natural selection in this section anddescribe the role that the environment plays in thetheory.

6. Identifying Relationships A population of rabbitsevolves thicker fur in response to a colder climate. Isthis an example of coevolution? Explain your answer.

READING SKILLS


FIELD ACTIVITYFIELD ACTIVITY Artificial Selection Look aroundyour school grounds and the areaaround your home for possibleexamples of artificial selection.Observe and report on any exam-ples you can find.

Dogs are one example of artifi-cial selection mentioned in thischapter, but you will probablyfind many more plant examples.Record your observations in your EcoLog.

Figure 11 � The evolution of resist-ance to a pesticide starts when thepesticide is sprayed on the corn.Most of the insects are killed, but afew resistant ones survive. After eachspraying, the insect population con-tains a larger proportion of resistantorganisms.

The survivorspass the trait forinsecticide resistanceto their offspring.

When the same insecticide is usedagain, more insects survive becausemore of them are resistant.

Insect pests are sprayed withan insecticide. Only a few resistant insects survive.

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Life on Earth is incredibly diverse. Take a walk in a park, andyou will see trees, birds, insects, and maybe fish in a stream. Allof these organisms are living, but they are all very different fromone another.

Most scientists classify organisms into six kingdoms, asdescribed in Table 2, based on different characteristics. Membersof the six kingdoms get their food in different ways and are madeup of different types of cells, the smallest unit of biologicalorganization. The cells of animals, plants, fungi, and protists con-tain a nucleus (NOO klee uhs), which consists of a membranethat surrounds a cell’s genetic material. Bacteria, fungi, andplants all have cell walls, structures that surround their cells andprovide them with support.

Archaebacteria and EubacteriaOrganisms in the kingdoms Archaebacteria and Eubacteria sharea lot of features, even though they are not closely related. Theyare microscopic, single-celled organisms that usually have cellwalls and reproduce by dividing in half. Unlike all other organ-isms, members of Archaebacteria and Eubacteria lack nuclei.

are often found in extreme places, such as hotsprings. Eubacteria are very common and can be found in soiland animal bodies. Many types of eubacteria are commonlyreferred to as bacteria.

Archaebacteria

Objectives� Name the six kingdoms of organ-

isms and identify two characteris-tics of each.

� Explain the importance of bacteriaand fungi in the environment.

� Describe the importance of pro-tists in the ocean environment.

� Describe how angiosperms andanimals depend on each other.

� Explain why insects are such suc-cessful animals.

Key TermsArchaebacteria Eubacteriafungusprotistgymnospermangiosperminvertebratevertebrate

S E C T I O N 3

The Diversity of Living Things

The Kingdoms of Life

Kingdom Characteristics Examples

corals, sponges, worms, insects, fish, reptiles, birds, and mammals

many cells; no cell walls; ingest theirfood; live on land and in water

Animals

ferns, mosses, trees, herbs, and grassesmany cells; make their own food by photosynthesis; have cell walls

Plants

diatoms, dinoflagellates (red tide), amoebas,trypanosomes, paramecia, and Euglena

most single celled but some have manycells; most live in water

Protists

yeasts, mushrooms, molds, mildews, and rusts

absorb their food through their body sur-face; have cell walls; most live on land

Fungi

proteobacteria (common in soils and inanimal intestines) and cyanobacteria (alsocalled blue-green algae)

single celled; lack cell nuclei; reproduceby dividing in half; incredibly common

Eubacteria

methanogens (live in swamps and produce methane gas) and extreme thermophiles (live in hot springs)

single celled; lack cell nuclei; reproduceby dividing in half; often found in harsh environments

Archaebacteria

Table 2 �

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Bacteria and the Environment Bacteria play manyimportant roles in the environment. Some kinds of bac-teria break down the remains and wastes of other organ-isms and return nutrients to the soil. Others recyclemineral nutrients, such as nitrogen and phosphorous.For example, certain kinds of bacteria play a veryimportant role by converting nitrogen in the air into aform that plants can use. Nitrogen is important becauseit is a main component of proteins and genetic material.

Bacteria also allow many organisms, including humans,to extract certain nutrients from their food. The bacteriain Figure 12 are Escherichia coli, or E. coli, a bacteriumfound in the intestines of humans and other animals.Here, E. coli helps digest food and release vitamins thathumans need. A different form of E. coli can causesevere food poisoning.

FungiA (plural, fungi) is an organism whose cells have nucleiand cell walls. A mushroom is the reproductive structure of a fun-gus. The rest of the fungus is an underground network of fibers.These fibers absorb food from decaying organisms in the soil.

Fungi get their food by releasing chemicals that help breakdown organic matter, and then absorbing the nutrients. The bodies of most fungi are a huge network of threads that growthrough the soil, dead wood, or other material on which thefungi are feeding. Like bacteria, fungi play an important role inthe environment by breaking down the bodies and body parts of dead organisms.

Like bacteria, some fungi cause diseases, such as athlete’sfoot. Other fungi add flavor to food. The fungus in blue cheese,shown in Figure 13, gives the cheese its strong flavor. And fungicalled yeasts produce the gas that makes bread rise.

Name one way that bacteria and fungi are similarand one way that they are different.■●✓ Reading Check

fungus

Section 3 109

Figure 12 � The long, orangeobjects in the image above are E. colibacteria as they appear under amicroscope.

Figure 13 � A mushroom (left) is thereproductive structure of a fungusthat lives in the soil. The cheese(above) gets its taste and its bluecolor from a fungus.

Spider MapCreate the

Graphic Organizer entitled“Spider Map” described in theAppendix. Label the circle“Kingdoms.” Create a leg for eachkingdom. Then, fill in the map with detailsabout the organisms in each kingdom.

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ProtistsMost people have some idea what bacteria and fungi are, but fewcould define a protist. are a diverse group of one-celledorganisms and their many-celled relatives. Some, such as amoebas,are animallike. Others, such as the kelp in Figure 14, are plantlike.

Still others are more like fungi. Most protists are one-celledmicroscopic organisms. This group includes amoebas and

diatoms (DIE uh TAHMS). Diatoms, shown in Figure 14,float on the ocean surface. The most infamous protist isPlasmodium, the one-celled organism that causes the dis-ease malaria. From an environmental standpoint, themost important protists are probably algae. Algae are

plantlike protists that can make their own food using thesun’s energy. Green pond “scum” and seaweed are exam-

ples of algae. Algae range in size from the giant kelp to theone-celled phytoplankton, which are the initial source of food inmost ocean and freshwater ecosystems.

PlantsPlants are many-celled organisms that have cell walls and thatmake their own food using the sun’s energy. Most plants live onland, where the resources a plant needs are separated between theair and the soil. Sunlight, oxygen, and carbon dioxide are in theair, and minerals and water are in the soil. Plants have roots thataccess water and nutrients in the soil and leaves that collect lightand gases in the air. Leaves and roots are connected by vasculartissue, a system of tubes that carries water and food. Vascular tis-sue has thick cell walls, so a wheat plant or a tree is like a build-ing supported by its plumbing.

Lower Plants The first land plants had no vascular tissue, andthey also had swimming sperm. As a result, these early plantscould not grow very large and had to live in damp places. Theirdescendants alive today are small plants such as mosses. Fernsand club mosses were the first vascular plants. Some of the firstferns were as large as small trees. Tree ferns still live in the trop-ics and in New Zealand today. Some examples of lower plantsare shown in Figure 15.

Protists

110 Chapter 4

BiologyConnection to

Cell Size Every cell mustexchange substances with itsenvironment across its surface.The larger the cell, the smaller itssurface is compared with its vol-ume. So the larger the cell, themore slowly substances movefrom outside the cell to itsinterior. This relationship limitsmost cells to microscopic sizes.

Figure 14 � Kelp (left) are hugeprotists with many cells that liveattached to the ocean floor. Themicroscopic diatoms (right) are protists that live in the plankton.

Figure 15 � Lower plants, such asthese mosses and ferns, live in dampplaces because they need water toreproduce.

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Gymnosperms Pine trees and other evergreens with needle-likeleaves are gymnosperms (JIM noh SPUHRMZ). arewoody plants that produce seeds, but their seeds are not enclosedin fruits. Gymnosperms such as pine trees are also called conifersbecause their seeds are inside cones, as shown in Figure 16.

Gymnosperms have several adaptations that allow them to livein drier conditions than lower plants can. Gymnosperms producepollen, which protects and moves sperm between plants. Theseplants also produce seeds, which protect developing plants fromdrying out. And a conifer’s needle-like leaves lose little water.Much of our lumber and paper comes from gymnosperms.

Angiosperms Most land plants today are (AN jeeoh SPUHRMZ), flowering plants that produce seeds in fruit. All ofthe plants in Figure 17 are angiosperms. The flower is the repro-ductive structure of the plant. Some angiosperms, such as grasses,have small flowers that produce pollen that is carried by thewind. Other angiosperms have large flowers that attract insectsor birds to carry their pollen to other plants. Many floweringplants depend on animals to disperse their seeds and carry theirpollen. For example, a bird that eats a fruit will drop the seedselsewhere, where they may grow into new plants.

Most land animals could not survive without floweringplants. Most of the food we eat, such as wheat, rice, beans,oranges, and lettuce, comes from flowering plants. Building mate-rials and fibers, such as oak and cotton, also come from flower-ing plants.

How do angiosperms depend on animals, and howdo animals depend on angiosperms?■●✓ Reading Check

angiosperms

Gymnosperms

Section 3 The Diversity of Living Things 111

Figure 16 � This gymnosperm hasmale and female reproductive struc-tures called cones.

Figure 17 � This meadow contains awide array of angiosperms, includinggrasses, trees, and wildflowers.

QuickLABPollen andFlower DiversityProcedure1. Use a cotton swab to collect

pollen from a common flower-ing plant.

2. Tap the cotton swab on amicroscope slide and cover theslide with a cover slip.

3. Examine the slide under amicroscope, and draw thepollen grains in your EcoLog.

4. Repeat this exercise with agrass plant in bloom.

Analysis1. Based on the structure of the

flower and the pollen grains,explain which plant is pollinatedby insects and which is polli-nated by wind.

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AnimalsAnimals cannot make their own food like plants can. They haveto take in food from their environment. In addition, animal cellshave no cell walls, so animals’ bodies are soft and flexible. Someanimals have evolved hard skeletons against which their musclescan pull to move their bodies. As a result, animals are much moremobile than plants and all animals move around in their environ-ments during at least one stage in their lives.

Invertebrates Animals that lack backbones are(in VUHR tuh brits). Many invertebrates live attached to hardsurfaces in the ocean and filter their food out of the water. Theseorganisms move around only when they are larvae (juveniles). Atthis early stage of life, they are part of the ocean’s floating plank-ton. Filter feeders include corals, various worms, and molluskssuch as clams and oysters. Figure 18 shows a variety of inverte-brates. Other invertebrates, including squid in the ocean andinsects on land, move around actively in search of food.

More insects exist on Earth than any other type of animal.Insects have a waterproof external skeleton that keeps them fromlosing water in dry environments. Insects move quickly and theyreproduce quickly. Also, most insects can fly. Their small sizeallows them to live on little food and to hide from enemies insmall spaces, such as a seed or in the hair of a mammal.

Many insects and plants have evolved together and depend oneach other to survive. Insects carry pollen from male parts of flowersto female parts of flowers to fertilize a plant’s egg, which developsinto a fruit. Without insect pollinators, we would not have toma-toes, cucumbers, apples, and many other crops. Insects also eatother insects that we consider to be pests. But, humans and insectsare often enemies. Bloodsucking insects transmit human diseases,such as malaria, sleeping sickness, and West Nile virus. Insectsprobably do more damage indirectly, however, by eating our crops.

invertebrates

MATHPRACTICEInsect Survival Mostinvertebrates produce large numbers of offspring. Most ofthese offspring die before reachingadulthood. Suppose an insect lays80 eggs on a plant. If 70 percentof the eggs hatch and 80 percentof those that hatch die beforereaching adulthood, how manyinsects will reach adulthood?

Figure 18 � Examples of inverte-brates include the banana slug (left), the leaf-footed bug (middle), and the cuttlefish (right).

112 Chapter 4

www.scilinks.orgTopic: InvertebratesCode: HE80812

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Vertebrates Animals that have backbones are calledMembers of three vertebrate groups are shown in Figure 19. Thefirst vertebrates were fish, but today most vertebrates live on land.Amphibians, which include toads, frogs, and salamanders, arepartially aquatic. Nearly all amphibians must return to water tolay their eggs.

The first vertebrates to complete their entire life cycle on landwere the reptiles, which today include turtles, lizards, snakes, andcrocodiles. These animals have an almost waterproof egg, whichallows the egg to hatch on land, away from predators in the water.

Birds are warm-blooded vertebrates with feathers. Bird eggshave hard shells. Adult birds keep their eggs and young warm untilthey develop insulating layers of fat and feathers. Mammals arewarm-blooded vertebrates that have fur and feed their young milk.The ability to maintain a high body temperature allows birds andmammals to live in cold areas, where other animals cannot survive.

vertebrates.

Section 3 The Diversity of Living Things 113

1. Describe how animals and angiosperms depend oneach other. Write a short paragraph to explain youranswer.

2. Describe the importance of protists in the ocean.

3. Name the six kingdoms of life, and give two charac-teristics of each.

4. Explain the importance of bacteria and fungi in theenvironment.

CRITICAL THINKING5. Analyzing Relationships Explain how the large

number and wide distribution of angiosperm speciesis related to the success of insects.

6. Understanding Concepts Write a short paragraphthat compares the reproductive structures of gym-nosperms and angiosperms. WRITING SKILLS

WRITING SKILLS


EcofactConserving Water Arthropodsand vertebrates are the only twogroups of animals that have adap-tations that prevent dehydration soeffectively that some of them canmove about freely on land on adry, sunny day.

Figure 19 � Examples of vertebratesinclude the toco toucan (left), theblue-spotted stingray (middle), andthe snow leopard (right).

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HighlightsC H A P T E R 4

1 Ecosystems: Everything IsConnected

2 Evolution

3 The Diversity of Living Things

Key Termsecosystem, 99biotic factor, 100abiotic factor, 100organism, 101species, 101population, 101community, 102habitat, 102

Main Ideas� Ecosystems are composed of many intercon-nected parts that often interact in complex ways.

� An ecosystem is all the different organismsliving in an area as well as the physical environment.

� Organisms live as populations of one speciesin communities with other species. Each specieshas its own habitat, or type of place that it lives.

natural selection, 103evolution, 103adaptation, 105artificial selection,

106resistance, 107

� The naturalist Charles Darwin used the termnatural selection to describe the survival andreproduction of organisms with particulartraits.

� Darwin proposed that natural selection isresponsible for evolution—a change in thegenetic characteristics of a population fromone generation to the next.

� By selecting which domesticated animals andplants breed, humans cause evolution by artifi-cial selection.

� We have unintentionally selected for peststhat are resistant to pesticides and for bacteriathat are resistant to antibiotics.

archaebacteria, 108eubacteria, 108fungus, 109protist, 110gymnosperm, 111angiosperm, 111invertebrate, 112vertebrate, 113

� Organisms can be divided into six kingdoms,which are distinguished by the types of cellsthey possess and how they obtain their food.

� Bacteria and fungi play the important envi-ronmental roles of breaking down dead organ-isms and recycling nutrients.

� Gymnosperms, which include the conifers,are the earliest plants with seeds. Angiospermsare flowering plants.

� Insects, invertebrates that are the most suc-cessful animals on Earth, affect humans in bothpositive and negative ways.

� Vertebrates, or animals with backbones,include fish, amphibians, reptiles, birds, andmammals.

114 Chapter 4 Highlights

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Review

Chapter 4 Review 115

Using Key TermsUse each of the following terms in a separatesentence.

1. adaptation2. invertebrate3. abiotic factor4. habitat5. species

For each pair of terms, explain how the meaningsof the terms differ.

6. community and population7. evolution and natural selection8. gymnosperm and angiosperm9. bacteria and protists

Understanding Key Ideas10. Which of the following pairs of organisms

belong to the same population?a. a dog and a catb. a marigold and a geraniumc. a human mother and her childd. a spider and a cockroach

11. Which of these phrases does not describepart of the process of evolution by naturalselection?a. the environment contains limited resources b. organisms produce more offspring than

will survive to reproducec. communities include populations of several

speciesd. organisms in a population differ in their

traits

12. Which of the following components of anecosystem are not abiotic factors?a. windb. small rocksc. sunlightd. tree branches

13. Some snakes produce a powerful poison thatparalyzes their prey. This poison is an exam-ple ofa. resistance.b. an adaptation.c. a reptile.d. an abiotic factor.

14. Angiosperms called roses come in a varietyof shapes and colors as a result ofa. natural selection.b. coevolution.c. different ecosystems.d. artificial selection.

15. Single-celled organisms that live in swampsand produce methane gas area. protists.b. archaebacteria.c. fungi.d. eubacteria.

16. Which of the following statements aboutprotists is not true?a. Most of them live in water.b. Some of them cause diseases in humans.c. They contain genetic material.d. Their cells have no nucleus.

17. Which of the following statements aboutplants is not true?a. They make their food from oxygen and

water through photosynthesis.b. Land plants have cell walls that help hold

their stems upright.c. They have adaptations that help prevent

water loss.d. Plants absorb nutrients through their roots.

C H A P T E R 4

Make an Outline After reading each section,summarize the main ideas into a short outline,leaving space between each entry. Then writethe key terms under the subsection in whichthey are introduced, followed by a short defini-tion for each.

STUDY TIP

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May June July August0

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ReviewShort Answer18. List the five components that an ecosystem

must contain to survive indefinitely.19. What is the difference between biotic and

abiotic factors in an ecosystem?20. What is the difference between adaptation

and evolution?21. Describe the three steps by which a population

of insects becomes resistant to a pesticide.22. List the six kingdoms of organisms and the

characteristics of each kingdom.

Interpreting GraphicsBelow is a graph that shows the number ofaphids on a rose bush during one summer. Theroses were sprayed with a pesticide three times,as shown. Use the graph to answer questions 23and 24.23. What evidence is there that the pesticide

killed aphids?24. Aphids have a generation time of about 10

days. Is there any evidence that the aphidsevolved resistance to the pesticide during thesummer? Explain your answer.

Concept Mapping25. Use the following terms to create a concept

map: ecosystem, abiotic factor, biotic factor,population, species, community, and habitat.

Critical Thinking26. Analyzing Ideas Can a person evolve? Read

the description of evolution in this chapterand explain why or why not.

27. Making Inferences A scientist applies astrong fungicide, a chemical that kills fungi,to an area of forest soil every week duringOctober and November. How might thisarea look different from the surroundingground at the end of the experiment?

28. Drawing Conclusions In what building inyour community do you think bacteria areevolving resistance to antibiotics most rap-idly? Explain your answer.

29. Evaluating Assumptions Many peopleassume that the human population is nolonger evolving. Do you think these peopleare right? Explain your answer.

Cross-Disciplinary Connection30. Geography Find out how the isolation of

populations on islands has affected theirevolution. Research a well-known example,such as the animals and plants of Madagascar,the Galápagos Islands, or the HawaiianIslands. Write a short report on your find-ings.

Portfolio Project31. Study an Ecosystem Observe an ecosystem

near you, such as a pond or a field. Identifybiotic and abiotic factors and as many popu-lations of organisms as you can. Do not tryto identify the organisms precisely. Just listthem, for example, as spiders, ants, grass,not as a specific type. Make a poster show-ing the different populations. Put the organ-isms into columns to show which of thekingdoms they belong to.

WRITING SKILLS

READING SKILLS

C H A P T E R 4

116 Chapter 4 Review

?

? ?

Aphid Population Changes Over Multiple Pesticide Sprayings

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Chapter 4 Review 117

Read the passage below, and then answerthe questions that follow.

Some Central American acacia trees, calledant acacias, have a mutually beneficial rela-tionship with ants that live on them. The treeshave several structures that benefit the ants.The trees have hollow thorns in which theants live, glands that produce sugary nectar,and swollen leaf tips, which the ants removeand feed to their larvae.

The ants reduce the damage that otherorganisms do to the tree. They remove dust,fungus spores, and spider webs. They destroyseedlings of other plants that sprout under thetree, so that the tree can obtain water andnutrients without competition from otherplants. The ants sting animals that try to eatthe tree.

Proof that the ants are valuable to the aca-cia tree comes from studies in which the antsare removed. Fungi invade the tree, it is eatenby herbivores, and it grows more slowly.When ants are removed from the tree, it usu-ally dies in a few months.

1. According to the passage, which of thefollowing statements is not true?a. Ants and ant acacias have evolved a

relationship beneficial to both of them.b. The ants prevent fungi from growing

on the acacia.c. The tree would benefit from not

having ants.d. The ants benefit from living on

the tree.

2. What is the advantage to an acacia ofnot having other plants grow nearby?a. Ants cannot crawl onto the acacia

from the other plants.b. The acacia keeps more ants for itself.c. This reduces competition for water

and nutrients.d. This reduces competition for fungi.

MATH SKILLS

Use the graph below to answer questions 32–33.32. Analyzing Data The graph below shows the

mass of different types of organisms found ina meadow. How much greater is the mass ofthe plants than that of the animals?

33. Analyzing Data What is the ratio of the massof the bacteria to the mass of the fungi?

WRITING SKILLS

34. Communicating Main Ideas Why is evolu-tion considered to be such an important ideain biology?

35. Outlining Topics Outline the essentialsteps in the evolution of pesticide resistancein insects.

0

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Bacteria Plants Fungi Animals Protists

Mass of Organisms in a Meadow

Kilo

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ms

READING SKILLS

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CC H A P T E R 4

118 Chapter 4 Standardized Test Prep

Standardized Test PrepUnderstanding ConceptsDirections (1–4): For each question, write on aseparate sheet of paper the letter of the correctanswer.

1 What is the term for the area where organisms live together with their physicalenvironment?A. biomeB. biosphereC. ecosystemD. population

2 Which of the following describes the theoryof natural selection?F. Organisms with desired traits are selected

for reproduction.G. Heredity determines which organisms

will survive in their environment.H. Traits are developed in organisms in

response to interaction with other organisms.

I. Organisms with strong survival traits are more likely to pass on the traits inreproduction.

3 What inherited trait increases an organism’schance of survival and reproduction in acertain environment?A. adaptationB. characteristicC. evolutionD. natural selection

4 What are the six kingdoms of life?F. Archaebacteria, Eubacteria, Fungi,

Protists, Plants, AnimalsG. Eubacteria, Fungi, Protists, Plants, Land

Animals, Marine AnimalsH. Archaebacteria, Fungi, Plantlike Protists,

Animal-like Protists, Plants, AnimalsI. Bacteria, Fungi, Protists, Flowering

Plants, Non-flowering Plants, Animals

Directions (5–6): For each question, write a shortresponse.

5 Everything in nature is connected. Use theconcept of interdependence to analyze howan ecosystem works.

6 Describe one of the important roles of bacteria.

Reading SkillsDirections (7–9): Read the passage below. Thenanswer the questions.

Ecosystems are composed of many intercon-nected parts that often interact in complexways. People often think of ecosystems as iso-lated from each other, but ecosystems do nothave clear boundaries. Things move from oneecosystem into another.

Ecosystems are made up of both living andnonliving things. Biotic factors are the livingand once-living parts of an ecosystem, including all the plants and animals. Biotic factors include dead organisms, dead parts oforganisms, such as leaves, and the organisms’waste products. The biotic parts of an ecosys-tem interact with the abiotic factors, the non-living parts of the ecosystem. There aredifferent levels in the ecological organization,from the individual organism to the biosphere.

7 What is one example of an abiotic factor?A. armadilloB. carnationC. robinD. rock

8 Why would it be incorrect to describeecosystems as being isolated from eachother?F. All ecosystems have different species.G. Things can move from one ecosystem

into another because ecosystems do nothave clear boundaries.

H. Ecosystems have biotic and abiotic factors.

I. Both ecosystems and communities havebiotic and abiotic factors.

9 State the kinds of biotic factors that wouldbe found in an ocean ecosystem.

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Chapter 4 Standardized Test Prep 119

TestAllow a few minutesat the end of the test-taking period to checkfor mistakes made inmarking answers.

Interpreting GraphicsDirections (10–12): For each question below, record the correct answer ona separate sheet of paper.

The map below shows changes in forest cover in Costa Rica over 40 years.Use this map to answer questions 10 through 12.

Forest Cover in Costa Rica

0 Approximately what percentage of Costa Rica was covered by forestin 1947?A. 25%B. 33%C. 50%D. 75%

q What conclusion can be drawn about the forest cover of Costa Rica?F. Most of the remaining forests are near cities.G. The remaining forests are concentrated along the western coast.H. Costa Rica lost more than half of its forest cover in less than

50 years.I. Deforestation has accounted for little change in Costa Rica’s

environment.

w What can be inferred about organisms adapted to living in trees inCosta Rica?A. Organisms that are adapted for living in trees will continue to

thrive across the country.B. Organisms that are adapted for living in trees will be eliminated

from the country’s environment.C. Organisms that are adapted for living in trees will continue to

thrive in areas that used to have forest.D. Organisms that are adapted for living in trees will thrive in forested

areas but struggle in areas that no longer have trees.

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120 Chapter 4 Inquiry Lab

How Do Brine Shrimp Select a Habitat?Different organisms are adapted for life in different habitats. Forexample, brine shrimp are small crustaceans that live in saltwaterlakes. Organisms select habitats that provide the conditions, suchas a specific temperature range and amount of light, to whichthey are best adapted. In this investigation, you will explore habi-tat selection by brine shrimp and determine which environmentalconditions they prefer.

ProcedureEstablish a Control Group

1. To make a test chamber and to establish a control group,divide a piece of plastic tubing into four sections by makinga mark at 10 cm, 20 cm, and 30 cm from one end. Label thesections "1", "2", "3", and "4".

2. Place a cork in one end of the tubing. Then transfer 50 mLof brine shrimp culture to the tubing. Place a cork in theother end of the tubing. Set the tube aside, and let the brineshrimp move about the tube for 30 min.

3. After 30 min, divide the tubing into four sections by placinga screw clamp at each mark on the tubing. While someone inyour group holds the corks firmly in place, tighten the mid-dle clamp at 20 cm and then tighten the other two clamps.

4. Remove the cork from the end of section 1 and pour the con-tents of section 1 into a test tube labeled "1." Repeat thisstep for the other sections by loosening the screw clamps andpouring the contents of each section into their correspondingtest tubes.

5. To get an accurate count for the number of brine shrimp ineach test tube, place a stopper on test tube 1, and invert thetube gently to distribute the shrimp. Use a pipet to transfer a 1mL sample of the culture to a Petri dish. Add a few drops ofDetain™ to the sample so that the brine shrimp move slower.Count and record the number of brine shrimp in the Petri dish.

Objectives� Observe

the behavior of brine shrimp.� Identify a

variable, and design an experimentto test the effect of the variable onhabitat selection by brine shrimp.

Materialsaluminum foilbrine shrimp culturecorks sized to fit tubingDetain™ or methyl cellulosefluorescent lamp or grow lightfunnelgraduated cylinder or beakerhot-water bagice bagmetric rulerPetri dishpipetplastic tubing, 40cm � 1cm,

clear, flexiblescreen, piecesscrew clampstapetest-tube racktest tubes with stoppers

USING SCIENTIFIC METHODS

USING SCIENTIFIC METHODS

Inquiry Lab: DESIGN YOUR OWNC H A P T E R 4

� Making a Test Chamber Use ascrew clamp to divide one section oftubing from another.

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Chapter 4 Inquiry Lab 121

6. Empty the Petri dish, and take two more 1 mL samples ofbrine shrimp from test tube 1. Calculate the average of thethree samples recorded for test tube 1.

7. Repeat steps 5 and 6 for each of the remaining test tubes tocount the number of brine shrimp in each section of tubing.

Ask a Question

8. Write a question you would like to explore about brineshrimp habitat selection. For example, you can explorehow temperature or light affects brine shrimp. Toexplore the question, design an experiment that uses thematerials listed for this lab.

9. Write a procedure and a list of safety precautions foryour group’s experiment. Have your teacher approve yourprocedure and precautions before you begin the experiment.

10. Set up and conduct your group’s experiment.

Analysis 1. Constructing Graphs Make a bar graph of your data. Plot

the environmental variable on the x-axis and the number ofbrine shrimp on the y-axis.

2. Evaluating Results How did the brine shrimp react tochanges in the environment?

3. Evaluating Methods Why did you have to have a control inyour experiment?

4. Evaluating Methods Why did you record the average ofthree samples to count the number of brine shrimp in eachtest tube in steps 6 and 7?

Conclusions5. Drawing Conclusions What can you conclude from your

results about the types of habitat that brine shrimp prefer?

1. Formulating Hypotheses Now that you have observedbrine shrimp, write a hypothesis about how brine shrimpselect a habitat that could be explored with anotherexperiment, other than the one you performed in this lab.Formulate a prediction based on your hypothesis.

2. Evaluating Hypotheses Conduct an experiment to test yourprediction. Write a short explanation of your results. Didyour results support your prediction? Explain your answer.

Extension

� Brine Shrimp These crustaceanshave specific habitat preferences.

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122 Chapter 4 Making a Difference

BUTTERFLY ECOLOGIST Imagine millions of butterfliesswirling through the air like autumnleaves, clinging in tightly packedmasses to tree trunks and branches,and covering low-lying forest veg-etation like a luxurious, movingcarpet. According to AlfonsoAlonso-Mejía, this is quite a sightto see.

Every winter Alfonso climbs upto the few remote sites in centralMexico where about 150 millionmonarch butterflies spend the winter.He is researching the monarchsbecause he wants to help preservetheir habitat and the butterfliesthemselves. His work helped himearn a Ph.D. in ecology from theUniversity of Florida.

Monarchs are famous for theirlong-distance migration. The butter-flies that eventually find their wayto Mexico come from as far awayas the northeastern United Statesand southern Canada. Some of

them travel an amazing 3,200 kmbefore reaching central Mexico.

Wintering Habitat at RiskUnfortunately, the habitat that themonarchs travel long distances toreach is increasingly threatened byillegal logging and other humanactivities. Logging reduced the sizeof the wintering region by approxi-mately 90 percent over a 30-yearperiod, from about 1970 to 2000.Mexico has set aside five of theknown butterfly sites as sanctuar-ies, but even these are endangeredby people who cut down fir treesfor fuel or money.

Alfonso’s work is helpingMexican conservationists betterunderstand and protect monarchbutterflies. Especially important isAlfonso’s discovery that the mon-archs depend on bushlike vegeta-tion, called understory vegetation,that grows beneath the fir trees.

Keeping WarmAlfonso’s research showed that whenthe temperature falls below freezing,as it often does in the mountainswhere the monarchs winter, under-story vegetation can mean the differ-ence between life and death for somemonarchs. These conditions are lifethreatening to the monarchs becauselow temperatures (–1°C to 4°C, or30°F to 40°F) limit their movement.In fact, the butterflies are not evenable to fly at such low temperatures.They can only crawl. At even coldertemperatures (–7°C to –1°C, or 20°Fto 30°F), monarchs resting on theforest floor may freeze to death. Butif the forest has understory vege-tation, the monarchs can slowlyclimb the vegetation until they are atleast 10 cm above the ground, whereit is warmer. This tiny difference inelevation can provide a microclimatethat is warm enough to ensure themonarchs’ survival.

� Butterfly Man Alfonso exam-ines a monarch as part of

his efforts to under-stand its ecology.

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Chapter 4 Making a Difference 123

What Do You Think?As a migrating species, mon-archs spend part of their livesin the United States and partin Mexico. Should the U.S.and Mexico cooperate in theirefforts to understand andmanage the monarch? Shouldnations set up panels to man-age other migrating species,such as many songbirds?

The importance of understoryvegetation was not known beforeAlfonso did his research. Now,thanks to Alfonso’s work, Mexicanconservationists will better protectthe understory vegetation. And theMexican government has passed anew decree that protects monarchsin areas the butterflies are knownto use.

The Need for ConservationAlthough the monarchs continueto enjoy the forests where theyoverwinter, those forests are stillthreatened. There is little forest leftin this area, and the need forwood increases each year. Alfonsohopes his efforts will help protectthe monarch both now and in thefuture.

Now that he has completed hisPh.D., Alfonso is devoting himselfto preserving monarchs and otherorganisms. He works as director forconservation and development forthe Smithsonian Institutions

Monitoring and Assessment ofBiodiversity (MAB) program.

Information...If you are interested in learningmore about monarchs, includingtheir spectacular migration, visitthe Website for Monarch Watch.Monarch Watch is an organizationbased at the University of Kansasthat is dedicated to educating peo-ple about the monarch and pro-moting its conservation.

� Monarch Sanctuaries Monarchbutterflies spend the winter at forested sites just above Mexico City.

� A Sea of Orange At their over-wintering sites in Mexico, millions ofmonarchs cover trees and bushes in afluttering carpet of orange and black.

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