Week 9

Changes

to Classification Systems

Wildlife Biology

Upcoming Activities

Taxonomy

• Life on Earth has evolved over the past 4 billion years, creating a vast variety of species.
• Humans have been classifying living organisms for over 2,000 years.

• The science of classifying organisms is called taxonomy.

• Classification helps scientists understand both the current diversity and the evolutionary history of life.

• Modern classification systems are based on the Linnaean system, created by Swedish botanist Carl Linnaeus in the 1700s.

• Linnaeus classified organisms based on shared physical traits, such as the number of legs or leaf shape.

• The Linnaean system organizes living things into a hierarchy of groups called taxa, ranging from kingdom to species.

Using DNA Evidence

A new technology that allows us to see the genetic code (DNA) of an organism reveals a great deal about its relationship to other organisms. Scientists are reclassifying species based on shared DNA sequences.

Using DNA Evidence

A new technology that allows us to see the genetic code (DNA) of an organism reveals a great deal about its relationship to other organisms. Scientists are reclassifying species based on shared DNA sequences.

Skunks and Weasels

• DNA analysis has greatly changed how skunks are classified.
• It confirmed that skunks should be separated from the weasel family (Mustelidae).
• Skunks are now placed in their own family, Mephitidae.
• Skunks were once grouped with weasels because they shared similar physical traits, such as: Squat bodies, Strong claws, Prominent anal glands

• Genetic evidence showed skunks are distinct enough to deserve their own family.

• This DNA-based reclassification has improved our understanding of skunk evolution and relationships.

• It provides a clearer picture of the diversity within the skunk group.

• Giant pandas were originally classified in the raccoon family because of similar traits, such as: a “false thumb” (an extended wrist bone) and a similar diet.
• DNA sequencing revealed that giant pandas share a more recent common ancestor with bears.
• This evidence led to their reclassification into the bear family (Ursidae).
• The example shows how DNA analysis can refine or correct classifications.
• Genetic evidence provides a more accurate understanding of evolutionary relationships.

Giant Pandas

Why do classification systems continue to change over time?

9.2 Invasive Species

Wildlife are under threat from many different kinds of human activities, from directly destroying habitat to spreading invasive species and disease.Invasive Species are among the leading threats to native wildlife. Approximately 42 percent of threatened or endangered species are at risk due to invasive species.

• An invasive species can be any kind of living organism that are not native to an ecosystem and causes harm to the environment.
• They usually grow and reproduce quickly, and have potential to cause harm.
• An invasive species does not have to come from another country.
• For example, lake trout are native to the Great Lakes, but are considered to be an invasive species in Yellowstone Lake in Wyoming because they compete with native cutthroat trout for habitat.

Invasive Species

• Invasive species are primarily spread by human activities, often unintentionally.
• People, and the goods we use, travel around the world very quickly, and they often carry uninvited species with them.
• Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers.
• Insects can get into wood, shipping palettes, and crates that are shipped around the world.
• Some ornamental plants can escape into the wild and become invasive.
• Some invasive species are intentionally or accidentally released pets, like the Burmese python problem in the Florida Everglades.

Next week's Assignment 10.1

Invasive Species Poster Project