2 Human Activities and Biodiversity Th e r e a r e t h r e e general levels of biodiversity on earth. Ecosystem diversity

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2 Human Activities and Biodiversity Th e r e a r e t h r e e general levels of biodiversity on earth. Ecosystem diversity is the variation within and between ecosystems.

In this activity, you will look at some examples of how human activities have altered the biodiversity of groups of taxa.

Human Activities that Affect Biodiversity h a b i t a t de s t r u c t i o n Humans change natural habitats through such activities as agriculture, building, mining, forestry, and pollution.

When an introduced species causes or is likely to cause harm to the environment, the econ omy, or human health, the species is considered an invasive species.

1 2 Human Activities and Biodiversity Th e r e a r e t h r e e general levels of biodiversity on earth. Ecosystem diversity is the variation within and between ecosystems. Species diversity is the number of species that exist in an area. Genetic diversity is the variation in the genes within a population of organisms. In this activity, you will look at some examples of how human activities have altered the biodiversity of groups of taxa. Taxa (singular taxon) are levels of classification, for example species or genus. Challenge 00 How do humans alter the biodiversity of groups of taxa? Human Activities that Affect Biodiversity h a b i t a t de s t r u c t i o n Humans change natural habitats through such activities as agriculture, building, mining, forestry, and pollution. i n t r o d u c e d sp e c i e s Humans intentionally or accidentally move species from their native locations to new areas. When an introduced species causes or is likely to cause harm to the environment, the econ omy, or human health, the species is considered an invasive species. o v e r e x p l o i t a t i o n Humans harvest animals or plants for ecosystem services, such as for food, medicine, lumber, collecting, and trading. The harvesting is considered overexploitation when the rate of harvest exceeds the ability of the population to recover. Clearcutting of the Zambian rainforest. Japanese beetles were accidentally introduced into the United States in 1916, and have since been severely destructive to turfgrass and ornamental plants. So many striped narrow-headed softshell turtles have been taken from the wild for food and the international pet trade that natural populations are at risk. 422

Work by yourself to read your assigned scenario(s). As you read, fill in the columns on the chart. 4. In your group, take turns summarizing your assigned scenario(s).

2 Procedure 1. In your science notebook, copy the following chart. Give it an appropriate title. human activities and biodiversity Activity 2 Scenario Type(s) of human impact Type(s) of biodiversity altered 2. Follow your teacher s directions for which scenario(s) to read. 3. Work by yourself to read your assigned scenario(s). As you read, fill in the columns on the chart. 4. In your group, take turns summarizing your assigned scenario(s). As you listen, fill in the columns on the chart for each scenario that you did not read. disruption of ne t w o r k s Ecosystems encompass a network of interdependent interactions. If the population of one species declines or goes extinct, that affects others in the network. An example of a network that could be disrupted is a food web. b r e e d i n g an d cl o n i n g People breed and clone populations of other organisms for various purposes. In doing so they might, for example, decrease genetic diversity in species of edible plants to create uniformly desirable crops. A harmful algal bloom causes illness or death in fish, seabirds, marine mammals, and humans who eat seafood contaminated with a neurotoxin from the algae. Algal blooms also reduce the oxygen levels in bodies of water. A geneticist checks an ear of e xperimental corn for genetic changes. 423

3 Science & Global Issues/Biology evolution Vast amounts of rainforest in Borneo were cleared to plant oil palm trees. The Rainforests of Borneo From an airplane above the island of Borneo, you can see the sudden divide between the rainforest and the straight rows of oil palm trees that have displaced the forest. Borneo is a large island of more than 427,000 sq km (165,000 sq mi) between the South China and Java seas. On it are more than 15,000 known species of plants and some of the tallest tropical rainforests in the world. The rainforests are filled with an array of animals, including some that glide as they leap from tall trees, such as flying lizards, flying frogs, and flying snakes. Two species of gibbons and eight species of monkeys inhabit and climb in the trees. Sun bears, clouded leopards, elephants, orangutans, and rhinoceroses also live in and roam the rainforest. Even today scientists continue to discover species on the island that were never seen by other scientists before. The greatest threat to the biodiversity of Borneo is forest destruction. Over the past two decades, approximately 40 million acres of forest have been cleared. Parts of the forests were cleared to plant palm trees, the fruits of which produce oil for cooking, body lotions, and fuel. The forests have also been extensively logged for timber to use for building and making paper. At the rate at which the forests of Borneo are being cut, the risk of current and future loss of biodiversity on the island is high. The Potato in Ireland After the potato was brought to Ireland from Spain in the 17th century, the Irish found they could grow more food in a smaller area with less labor when they planted just one variety: the lumper potato. That potato turned out to be a good source of nutrition and became a staple crop for Irish peasants. Like other living organisms, however, the potato is susceptible to microbes that cause disease, and lumpers are particularly susceptible to the fungus Phytophthora infestans, which causes potato blight. Making the Irish food supply more vulnerable, the lumper 424

human activities and biodiversity Activity 2 In Ireland in the 1800s, potato blight killed whole crops of genetically identical lumper potatoes, causing widespread famine.

A putrid stench hit the air as entire fields of potatoes died in just a few days. While the potato blight reached all of Europe, only Ireland experienced devastating famine and suffering.

Cichlids and Nile Perch Within the last 200,000 years in Africa s huge Lake Victoria, more than 300 species of cichlid fish evolved to live in the various habitats in the lake.

a In the 1950s, the British government introduced the large Nile perch into the lake with the idea that the perch would provide the local people with a new protein source and a new

4 human activities and biodiversity Activity 2 In Ireland in the 1800s, potato blight killed whole crops of genetically identical lumper potatoes, causing widespread famine. potatoes were all genetically identical to each other. In 1845, spores of the potato blight fungus were carried by the wind from England. A putrid stench hit the air as entire fields of potatoes died in just a few days. While the potato blight reached all of Europe, only Ireland experienced devastating famine and suffering. One in eight Irish people died in three years. Cichlids and Nile Perch Within the last 200,000 years in Africa s huge Lake Victoria, more than 300 species of cichlid fish evolved to live in the various habitats in the lake. Some cichlids, such as tilapia, are edible, and some larger species are popular sport fishing prey. Genetic evidence suggests that the cichlids evolved from a common ancestor. a In the 1950s, the British government introduced the large Nile perch into the lake with the idea that the perch would provide the local people with a new protein source and a new commercial fishery. Unfortunately, the perch ate the cichlids and other fish. Because cichlids were also fished along with the perch, introducing the perch appears to be the reason for the extinction of as many as 200 species of cichlids and the decline of other fish, such as catfish and lungfish. When the Nile perch (a) was introduced into Lake Victoria, they ate the cichlids (b) and other fish that lived there. b 425

Science & Global Issues/Biology evolution In a further threat to the lake s biodiversity, the loss of the cichlid species that ate algae allowed the amount of algae in the lake to rise.

5 Science & Global Issues/Biology evolution In a further threat to the lake s biodiversity, the loss of the cichlid species that ate algae allowed the amount of algae in the lake to rise. Because algae consume oxygen, their abundance made it difficult for other small plants and animals in the lake to get enough oxygen for themselves. The Lake Victoria ecosystem is adjusting to these changes, but will not likely reach the level of biodiversity that existed before the introduction of Nile perch. The Dodo Bird The small Indian Ocean island of Mauritius was once home to populations of the large, flightless dodo bird, which had evolved over several million years on the island. Mauritius is isolated, and because they had little competition from other organisms the dodos had freely fed on fruit that had fallen to the ground. Those dodos with the ability to store large amounts of fat in times when food was scarce were better able to survive and reproduce. Eventually, over generations, the dodos increased in size. Flightlessness also evolved. As plant eaters in an environment with no predators, the inability to fly would have had no effect on the dodo s ability to survive. In the 16th and 17th centuries, Portuguese and Dutch explorers sailed to the island. The flightless dodos could not flee from humans who hunted them for food and for their eggs. The sailors also brought with them pigs, monkeys, and rats that fed on the dodos eggs and chicks, and perhaps even adult dodos. On a small island, the relatively small dodo population could not survive under these changed conditions. In a small population, the genetic diversity of the population is relatively low. When genetic diversity is low, there is a low probability that any individual in the population will have the trait(s) required for survival and reproduction if the environment changes. Eighty years after humans arrived, dodos became extinct. Dodo fossil bones confirm that the bird was flightless. 426

human activities and biodiversity Activity 2 Florida Panther By the 1950s, the once-large panther population of the southeastern United States had been hunted to near extinction because of the threat

6 human activities and biodiversity Activity 2 Florida Panther By the 1950s, the once-large panther population of the southeastern United States had been hunted to near extinction because of the threat people thought they posed to humans, livestock, and other animals. Today, urban and agricultural development and resulting habitat loss have decreased the panthers range to only 5% of what it originally was. In 2009, a record number of 16 Florida panthers were killed by cars. With fewer than 100 panthers total remaining in southern Florida, this is a significant loss to the endangered panther population. Florida panthers are found in forested areas, including the mixed swamp, pine, and hardwood forests of the Everglades. The Florida panther originally inhabited Florida, Louisiana, Arkansas, Mississippi, Alabama, Georgia, and parts of Tennessee and South Carolina. Between 1991 and 2003, more than 728,000 hectares (1.8 million acres) of forest in southern Florida were destroyed, and approximately 17,700 km (11,000 mi) of public roads were developed. As people took over more and more land the panther population in Florida became isolated by habitat loss. Their isolation prevented them from breeding and exchanging genes with other panther populations. The inbreeding has led to reduced fertility, heart abnormalities, and infectious diseases in the population. In 1995, eight female panthers from Texas were introduced into the Florida population in an effort to help it recover. However, evidence suggests that so far this strategy has had limited success. Missouri arkansas Mississippi tennessee Kentucky alabama Georgia north carolina South carolina atlantic ocean This depiction of the historic and current ranges of the Florida panther population shows how severely their habitat has been reduced. louisiana florida panther range historic range present range Gulf of Mexico florida 427

Science & Global Issues/Biology evolution Domestic Dogs Domestic dogs are members of the subspecies Canis lupus familiaris.

The wolf populations in various parts of the world were made up of genetically different individual wolves.

that appeared to be inherited. Soon people were breeding wolves for particular desired traits, such as abilities for hunting, herding, hauling, or protecting their masters.

Today there are hundreds of breeds of Canis lupus familiaris, from golden retrievers and poodles to chihuahuas and Pekingese lap dogs to pit bulls and rottweilers.

7 Science & Global Issues/Biology evolution Domestic Dogs Domestic dogs are members of the subspecies Canis lupus familiaris. They are the result of thousands of years of dog breeding that began about 14,000 years ago when humans first domesticated the gray wolf, Canis lupus. The wolf populations in various parts of the world were made up of genetically different individual wolves. As wolves that interacted socially with humans became part of human communities, people took notice of their natural variations and the behavioral traits in their offspring that appeared to be inherited. Soon people were breeding wolves for particular desired traits, such as abilities for hunting, herding, hauling, or protecting their masters. Over centuries of such artificial selection, the descendants of the wolves became what we recognize as dogs. Today there are hundreds of breeds of Canis lupus familiaris, from golden retrievers and poodles to chihuahuas and Pekingese lap dogs to pit bulls and rottweilers. Each breed has specific characteristics selected by the human breeders. For example, golden retrievers were bred to assist hunters by retrieving game. Because they are intelligent and sociable, they have also become popular as family pets. For a b After gray wolves (a) were domesticated by humans, they were bred over centuries to produce hundreds of kinds of modern dogs (b d). c d 428

human activities and biodiversity Activity 2 decades the art of dog breeding has been big business, with mating of dogs of the same breed to produce dogs for show or superior performance in certain

The media has labeled the newly created mixed breeds designer dogs, and some people are willing to pay thousands of dollars for such a puppy.

8 human activities and biodiversity Activity 2 decades the art of dog breeding has been big business, with mating of dogs of the same breed to produce dogs for show or superior performance in certain tasks. Now there is a trend to mate one breed with desirable traits to another with other desirable traits. The media has labeled the newly created mixed breeds designer dogs, and some people are willing to pay thousands of dollars for such a puppy. The labradoodle, for example, is a mix of labrador retriever and poodle. While not all of the offspring in a litter have the exact same mix of traits, labradoodles desired traits include a friendly, loyal disposition and a nonshedding coat. Labradoodle Flying Foxes Some of the most important pollinators and seed dispersers of plants in the South Pacific islands are flying foxes, which are actually bats with ears, eyes, and snout comprising what looks like the face of a fox. Flying foxes are mammals that can weigh up to 1 kg (2.2 lbs). Flying foxes feed on nectar, blossoms, pollen, and fruit. Reproduction of more than 79% of the plants of the Samoan islands is dependent on the flying fox for seed dispersal or pollination. In turn, the plants support much of the animal The endangered flying fox bat is an important pollinator. 429

9 Science & Global Issues/Biology evolution diversity on the island and provide ecosystem services for humans. The wild banana is an example of a tree that largely depends on flying foxes to spread the pollen from one tree or one banana flower to another. Because of their important role in pollination and seed dispersal, the flying fox population is crucial for the maintenance of the Pacific island ecosystem. Local people depend on the wild banana for food and as a source of fiber to make textiles, rope, and paper. A great threat to flying foxes, however, is people s taste for exotic foods. Each year from 1975 to 1990, between 8,000 and 29,000 flying foxes were hunted to supply the luxury food market. The bats are also hunted for their medicinal properties and sport. Populations of flying foxes are especially vulnerable to destruction by hunters and other pressures because most females do not begin reproducing until they are one-to-two-years old. Once they start reproducing, they give birth to only one offspring per year. The flying fox is classified as endangered under the United States Endangered Species Act, and cannot be imported into this country. Northern Elephant Seals Hundreds of thousands of northern elephant seals once lived in the Pacific Ocean with a range that spanned from the north in Alaska and British Columbia to the south in California. They are so named for their large size and the large nose that suggests an elephant s trunk. Male elephant seals grow to a weight of approximately 2,300 kg (5,000 lbs), and a length up to 4 m (14 ft), while mature females grow to weigh around 635 kg (1,400 lbs), and to be up to 3 m (11 ft) long. Northern elephant seal 430

10 human activities and biodiversity Activity 2 Elephant seals spend most of their time in the ocean but come ashore regularly to molt, breed, and give birth on land, making them a much easier target for hunters than whales. From 1820 to 1880, whale and seal hunters slaughtered whole colonies of elephant seals to make oil from their blubber. The blubber harvesting was so extensive that the species was nearly wiped out. In fact, estimates of their remaining population numbered from 20 to 100 individuals from the late 1880s to Scientists describe such a severe but temporary reduction in population size as a bottleneck. Beginning in the early 1900s, the Mexican and United States governments protected the elephant seals with a ban on their hunting, and their numbers gradually increased. Today, astonishingly, there are more than 100,000 northern elephant seals. Of some concern to conservationists, however, is that the current seal population has been traced through genetic testing back to just one male who survived to reproduce with females. This means the genetic diversity is very low. But so far, at least, the low genetic diversity has not hindered the growth of the elephant seal population. Analysis 1. For which scenario(s) did humans alter a. ecosystem diversity? b. species diversity? c. genetic diversity? 2. Explain how humans changed the ecosystem, species, and genetic diversity of the groups you identified in question What is the relationship between extinction and a. species diversity? b. genetic diversity? 4. Do you think it is important for humans to be aware of how we alter the genetic and species diversity of groups of organisms? Explain. Key vocabulary biodiversity ecosystem diversity genetic diversity species diversity taxa taxon 431

Activity 3, Humans Effects on Biodiversity. from the Evolution Unit of the SEPUP course. Science in Global Issues

Activity 3, Humans Effects on Biodiversity from the Evolution Unit of the SEPUP course Science in Global Issues For use only by teachers who attended the Biodiversity session at NSTA on March 19, 2009.