Finding the missing birds of Guam CHAPTER 10 EVOLUTION AND EXTINCTION A TROPICAL MURDER MYSTERY Finding the missing birds of Guam

Do Now What is the Brown Treesnake? How is it harmful to humans? How is it harmful on the island of Guam? How are scientists trying to eradicate the Brown Treesnake from Guam? Is it working?

Invasive species are hard-to-eradicate, non-native species that cause ecological, economic, or human health problems.

Extinctions are the complete loss of a species from an area Extinctions are the complete loss of a species from an area. They may be local (gone from an area) or global (gone for good).

Evolutionary biology helps us understand the diversity of life and how populations change over time. It does not study creation or the origin of life.

The island of Guam used to be home to 18 native species of birds. Answer: C

In the 1960s, Guam began losing its bird population In the 1960s, Guam began losing its bird population. By the 1980s, four species had gone extinct and 10 more species were in danger of extinction.

Guam’s scientists thought disease was the problem Guam’s scientists thought disease was the problem. Locals thought non-native snakes were the problem.

Before they started disappearing, the birds of Guam were a diverse bunch. Populations usually contain individuals that are genetically different from each other.

Populations need genetic diversity to evolve Populations need genetic diversity to evolve. If a new challenge—such as a new predator—the population’s survival depends on having individuals that can deal with the new species.

According to evolutionary theory, selective pressure on a population favors certain inherited traits over others. Answer: D SR: Add flood control as a choice here as well?

These traits include better camouflage, tolerance for drought, or enhanced sense of smell.

The traits that an environment favors are called adaptations The traits that an environment favors are called adaptations. The process by which these traits are passed on is called natural selection.

Do Now Considering what you already know about evolution and extinction, if a mass extinction occurred in 2014… Which Ecosystems would be most vulnerable? Be specific. What type of species would be vulnerable? What type of species would thrive? What factors of evolutionary biology are in effect here?

Individuals with adaptations are best suited for their environment and leave more offspring than those who are less suited.

Over time, the population will contain more and more of these better-adapted individuals and their offspring.

Ultimately, this changes how common certain genes are in the population.

When this occurs, the population has experienced evolution—or changes in the gene frequencies in a population.

It is important to note that individuals are selected for, but populations evolve.

Individuals do not change their own genetic makeup to produce new adaptations – they pass their traits on to the next generation.

Individuals may adjust their behavior to accommodate environmental changes, but if that trait is not genetically controlled, it cannot be inherited.

Under certain conditions, populations can diverge into subpopulations or even new species (speciation). Genetic Drift Bottleneck Founder Effect

Do Now Describe the differences between the following methods of populations diverging from their original genetic make-up. Genetic Drift Bottleneck Founder Effect Can a species believed to be extinct actually be surviving in an unknown area? Examples?

________________ is a change in gene frequency within a population. Clicker Question ________________ is a change in gene frequency within a population. A. Adaptation B. Evolution C. Natural Selection D. Genetic Diversity Answer: B

Do Now Please read the article. Do all species experience an increase in mortality with age? Why or why not? Does evolution lead to senescence? What are the evolutionary trade-offs between reproduction and mortality? How does this relate to evolution as we have studied in CH 10? Be Specific.

Lobsters will not die of old age…

Lobsters will not die of old age… why? Is this an evolutionary favorable characteristic?

In coevolution, two species provide the selective pressure that determines which of the other’s traits is favored by natural selection.

Extinction can occur quickly if the rate of change exceeds the ability of a population to adapt.

Studies proved the snakes were the culprit—the eradication of the birds happened so fast it prevented the birds from coevolving survival strategies. Answer: A

Extinction is nothing new: more than 99 percent of all species that have ever lived on the planet have gone extinct.

Today, most scientists agree we are witnessing a sixth mass extinction, largely driven by human actions.

Most scientists also agree that extinction rates are accelerating worldwide—although they disagree about the exact rate.

Humans also affect the evolution of populations through artificial selection: deciding which individuals to breed to produce a population with desired traits.

By changing an environment rapidly, humans apply new selective pressures to an environment – such as introducing tree snakes to Guam.

Our changes can be so great that natural selection can’t keep up and a population collapses.

In Guam, things are looking up for the birds—snakes are being controlled through trapping to allow the bird populations to recover.

Clicker Question If extinction is a natural process, should humans step in to protect animals that are becoming extinct? Yes No Why or why not? Open-ended discussion question

Selfish Genes How can genes be selfish? Is it advantageous from an evolutionary perspective? How are genes cooperative? Be specific. Agree or disagree with the following statement providing evidence from what we have learned in class. “Nature dooms all that damages what it depends on”