Environment

Biodiversity

Lecture 4

What Are the Major Types of Life on the Earth?

• Every organism is composed of one or more cells.

• Cell: • Known as the “building blocks of life” • Surrounded by a structure called the cell membrane

What Are the Major Types of Life on the Earth?

• Classification based on cell structure • Prokaryotic (bacterial cells)

• Cells enclosed by a membrane but containing no distinct nucleus or other internal parts enclosed by membranes

• Eukaryotic • All nonbacterial organisms

• Cells are encased in a membrane and have a distinct nucleus (a membrane-bounded structure containing genetic material in the form of DNA) and several other internal parts enclosed by membranes.

What Are the Major Types of Life on the Earth?

Taxonomies

Scientists group organisms into categories based on their greatly varying characteristics. • Taxonomic classification:

• Domain, kingdom, phylum, class, family, genus, and species

Kingdoms

• Archaebacteria • Eubacteria • Protista (algae and protozoans) • Plantae: Plants (mosses, ferns, and

flowering plants) • Fungi (mushrooms, molds, mildew,

and yeasts) • Animalia: Animals (invertebrates

and vertebrates)

Taxonomies video

• https://www.youtube.com/watch?v=kKwOlAqQoLk

Earth’s Organisms Are Many and Varied

• Species – group of organisms with characteristics that distinguish it from other groups of organisms.

• Estimated 7–10 million species exist • About 2 million species have been identified

• About half of those are insects

• Pollination is a vital ecosystem service performed by insects • Biological control

What Is Biodiversity and Why Is It Important?

• Biological diversity is the diversity of life on earth • Four components: • Species diversity

• Includes species richness (the number of different species) and evenness (comparative abundance of all species)

• Genetic diversity • Variety of genes in a population or species

• Ecosystem diversity • Biomes: regions with distinct climates and species

• Functional diversity • Biological and chemical processes, such as energy flow and matter recycling, needed

for the survival of species, communities, and ecosystems

What is Biodiversity?

• https://www.youtube.com/watch?v=b6Ua_zWDH6U

Species Diversity

• Species diversity includes species richness (number of different species) and evenness (comparative abundance of all species).

• If an ecosystem only has three species, its richness is low. But if there are an equal number of each of the three species, the species evenness is high.

• Species richness is highest in the tropics and declines as we move toward the poles.

• Most species rich environments are tropical rain forests, large tropical lakes, coral reefs, and the ocean-bottom zone.

Species Diversity

Functional Diversity

Functional diversity is the biological and chemical processes, such as energy flow and matter recycling, needed for the survival of species, communities, and ecosystems.

-What is/are the organism(s) doing? -How does it interact with other organisms and the environment

Genetic Diversity

• Variety of genes in a population or species • Genes contain genetic information that give rise to specific traits, or

characteristics, that are passed on to offspring through reproduction. • Species have a better chance of surviving and adapting to environmental changes

if they have greater genetic diversity.

Ecosystem Diversity

• Biomes: Regions with distinct climates and species (terrestrial classification)

• tropical rainforests, temperate forests, deserts, tundra, boreal forests, grasslands, and savanna

• Biomes differ in their community structure based on the types, relative sizes, and stratification of their plant species

Major Biomes across United States

Ecosystem Diversity

• Large areas of forest and other biomes have a core habitat and edge habitats with different environmental conditions and species, called edge effects

• Natural ecosystems within biomes rarely have distinct boundaries. • Instead, one ecosystem tends to merge with the next in a transitional zone

called an ecotone • Ecotone: a region containing a mixture of species from adjacent ecosystems along with

some migrant species not found in either of the bordering ecosystems

• Humans have fragmented many biomes into isolated patches with less core habitat and more edge habitat that supports fewer species.

What Role Do Species Play in Ecosystems?

• Each species plays a specific ecological role called its niche • Includes everything that affects survival and reproduction

• Water, space, sunlight, food, and temperatures • What it eats • How much water it drinks • When it reproduces • Niche is NOT the same as habitat, which is where a species lives • Related to functional diversity component of biodiversity

What Role Do Species Play in Ecosystems?

• Niches are used to classify species into 2 categories:

• Generalist species • Broad niche—wide range of tolerance

• Specialist species • Narrow niche—narrow range of tolerance

Niches

• Further classification of niches depends on the roles that species play in ecosystems:

• Native species normally live and thrive in a particular ecosystem

• Nonnative species migrate or are accidentally introduced into an ecosystem

Invasive Species

• https://www.youtube.com/watch?v=spTWwqVP_2s

Niches

• Further classification of niches depends on the roles that species play in ecosystems:

• Indicator species provide early warnings of environmental changes

• Lichens, Trout

Niches

• Further classification of niches depends on the roles that species play in ecosystems:

• Keystone species have a large effect on the types and abundance of other species (such as pollination and population regulation)

• E.g., Saguaro cactus – habitat, food • Species can play one or more roles in an ecosystem

• https://www.youtube.com/watch?v=JGcIp4YEKrc