4-5 What Is Species Diversity and Why Is It Important? Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

Species Diversity: Variety, Abundance of Species in a Particular Place (1) An important characteristic of a community and the ecosystem to which it belongs is its species diversity, or the ________________ and ________________ of species it contains Two important components of species diversity Species _______________: The number of different species in a given area Species _________________: comparative number of individuals of each species present number variety richness evenness

Variations in Species Richness and Species Evenness Low ________ Species Richness High Figure 4.12: These two types of ecosystems vary greatly in species richness. An example of high species richness is a coral reef (left), with a large number of different species. On the other hand, this grove of aspen trees in Alberta, Canada (right) has a small number of different species, or low species richness. Coral Reef Grove of Aspen Trees Fig. 4-12, p. 93

Species Diversity: Variety, Abundance of Species in a Particular Place (2) Diversity varies with _________________ location For most terrestrial plants and animals, species diversity is highest in the ______________ and declines as we move towards the ______________ The most species-rich communities Tropical rain forests Coral reefs Ocean bottom zone Large tropical lakes geographic tropics poles

Science Focus: Species Richness on Islands In the 1960s, Robert _____________ and Edward O. _____________ set out to discover why large islands have more species richness than small islands They used their findings to propose the …. - species equilibrium model - also called the theory of __________ _______________ MacArthur Wilson island biogeography Edward O. Wilson

Science Focus: Species Richness on Islands According to this widely accepted scientific theory, the species richness found on an island is determined by the interaction of two factors: Rate of new species ____________________ Rate at which species become ________________ Immigration and extinction rates are affected by… Island ______________ distance from the ___________________ immigration extinct size mainland

Science Focus: Species Richness on Islands Which would serve as a larger target for potential colonizers – a small island or a large island? Which would have more resources – a small island or large island? Would potential colonizers be more likely to reach an island close to the mainland or far away? Large island Large island Close to mainland

Species-Rich Ecosystems Tend to Be Productive and Sustainable Species richness seems to increase ______________ and ________________ or sustainability, and provide insurance against catastrophe How much species richness is needed is debatable The theory of island biogeography has also been extended to study of _____________________ Areas such as national parks or mountain ecosystems that are surrounded by developed or fragmented land productivity stability habitat islands

4-6 What Roles Do Species Play in an Ecosystem? Concept 4-6A Each species plays a specific ecological role called its niche. Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation—in a particular ecosystem.

Each Species Plays a Unique Role in Its Ecosystem An important principle of ecology is that each species has a specific ____________ to play in the ecosystems where it is found Ecological niche…often pronounced “nitch” Involves everything that affects _____________ and ______________ Water, space, sunlight, food, temperatures Not to be confused with a habitat…__________ where an organism lives role survival reproduction place

Each Species Plays a Unique Role in Its Ecosystem Generalist species – have ____________ niches or a _____________ range of tolerance They may live in many places, eat a variety of foods, often tolerate a wide range of environmental conditions Specialist species - occupy ______________ niches may only be able to live in one type of habitat, use only a few food sources, or tolerate a narrow range of climatic and environmental conditions broad wide narrow

Specialist Species and Generalist Species Niches Specialized diet of bamboo Can eat a wide variety of food…love to dig through human garbage! Endangered due to habitat loss and slow birth rates Figure 4.13: Specialist species such as the giant panda have a narrow niche (left) and generalist species such as the raccoon have a broad niche (right). Fig. 4-13, p. 95

Specialized Feeding Niches of Various Bird Species in a Coastal Wetland Specialized niches ________________ competition, but are more susceptible to degradation or environmental changes reduce Figure 4.14: This diagram illustrates the specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources. Fig. 4-14, p. 96

Case Study: Cockroaches: Nature’s Ultimate Survivors Have been around for 350 million years, outliving the dinosaurs 3500 species They have thrived because they are _______________ Eat almost anything Live in almost any climate (except the polar regions) Antennae and sensors that allow ____________ responses High reproductive rates – allows them to pass on beneficial traits like genetic ________________ to poisons generalists quick resistance

Species Can Play Five Major Roles within Ecosystems Native species - species that _________________ live and thrive in a particular ecosystem Nonnative species – _______________ into or are ________________ to an ecosystem…also called invasive, alien, or exotic species Indicator species – provide early _______________ of damage to a community or ecosystem Keystone species – have a large ___________ on the types and abundance of other species Foundation species – help to create or _______________ their habitats in ways that benefit other species normally migrate introduced warning effect enhance

Wild African Honey Bees “Killer Bees” Nonnative species…imported into ____________ intentionally to help increase honey production Ended up displacing native bees and reduced the honey supply Have since moved through Central America and the Southern U.S. Not gruesome killers, but they are ____________________ and unpredictable Brazil aggressive

Poison Dart Frog Indicator Species Amphibians were the first __________________ to set foot on land and historically have been good at adapting to environmental changes But since the 1980s, __________ amphibian species have been vanishing or declining worldwide vertebrates Figure 4.17: The well-known red-eyed tree frog (left) found in tropical rain forests in Mexico and Central America is currently not threatened with extinction. However, some species of the poison dart frog (right) found in the tropical forests of Brazil and southern Suriname are threatened with extinction, mostly because of an infectious fungus and habitat loss from logging and farming. This frog’s bright blue color warns predators that it is poisonous to eat. The toxic secretions of at least three of these species are used to poison the tips of blow darts that native peoples in the frog’s tropical habitat use for hunting. many Why are amphibians vanishing? Fig. 4-17a, p. 98

Case Study: Why Are Amphibians Vanishing? (1) Habitat loss and fragmentation Prolonged drought Pollution…exposure to _____________________ in ponds Increase in UV radiation Parasites…feed on amphibian ___________ Viral and fungal __________________…damages their skin and ability to take in water Climate change…correlation to atmospheric ______________ Overhunting…____________________ Nonnative predators and competitors pesticides eggs diseases warming frog legs

Case Study: Why Are Amphibians Vanishing? (2) Importance of amphibians Sensitive biological indicators of environmental ________________ Adult amphibians Important ecological roles in biological communities Eat ___________________ Serve as food in the __________________ of other aquatic organisms Genetic storehouse of pharmaceutical products waiting to be discovered Secretions have been used as __________________ and ___________________ changes Insects (mosquitoes) food webs painkillers antibiotics

Keystone Species Play Critical Roles in Their Ecosystems Keystone species: roles have a large effect on the types and abundances of other species ____________________ pollinators top predators American Alligator

Case Study: Why Should We Care about the American Alligator? 1930s-1960s: Hunters and poachers – killed off alligators to near extinction in the U.S. Importance of gator holes and nesting mounds the depressions they form hold ____________________ during dry spells Their nesting mounds are important _____________ and _________________ for other organisms Without the American alligator, dozens of other species would __________________ from coastal wetland ecosystems water feeding sites nesting grounds disappear

Foundation Species Help to Form the Bases of Ecosystems Foundation species - create or enhance their habitats, which benefit others Elephants – push over, break, and uproot trees…creating __________ patches where new ___________ may grow Benefits ______________ grazing animals Accelerates nutrient _________________ Beavers – ecological ___________________....build dams which create ponds and wetlands open plants small cycling engineers

Three Big Ideas ____________________ evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (also called natural selection.) Human activities are ________________ earth’s vital biodiversity by causing the extinction of species and by disrupting habitats. Each species plays a specific ecological role or _____________ in the ecosystem where it is found. Populations decreasing niche

Review Questions What is the difference between generalists and specialists? Identify the vocab term associated with the role of each species… killer bee certain amphibians elephant American alligator 3. What effect does species richness have on an ecosystem? (broad niche) (narrow niche) Nonnative (Brazil) Indicator sp. Foundation sp. Keystone sp. Increases productivity and stability