Unit 6 - Introduction

How do we adapt?

Why do some organisms survive and some perish?

Thylacine (Tasmanian wolf/tiger), Dodo bird, white rhino, passenger pigeon, golden toad

Adaptations▪ What are they?

▪ An adaptation is a physical or behavioral characteristic that has developed to allow an organism to better survive in its environment. Adaptations are the result of evolution, and may occur when a gene mutates, or changes by accident.

▪ That mutation causes the organism to better survive and reproduce, and it passes on that trait to its offspring. It can take many generations to develop an adaptation.

Two types of adaptations:

▪ Physical and behavioral

▪ One physical adaptation is a crab's hard shell, which protects it from predators, drying out and being crushed by waves.

▪ A behavioral adaptation in the oceans is the use of loud, low-frequency calls by fin whales to communicate with other whales over great distances.

Extinction -▪ Naturally caused – Extinction is a natural phenomenon, and we know this since we can document the extinction of species in the fossil record spanning more than 500 million years. It is either a failure to adapt to changing environments (physical and biological), or a species inability to adjust to rapidly changing circumstances.

▪ Caused by humans – Species play the roles in ecosystems that they evolved in order to ensure their own survival. The fact that ecosystems work, is the result of continuous selection of species and communities by the environment.

▪ There is absolutely no way in which humans can replace the functions of all the species that we are causing to go extinct, and we are rapidly eliminating the evolutionary potential and options for adaptation in the future.

Animals that are extinct because of humans!!

▪ Passenger pigeons - it was the most abundant bird species on Earth no so long ago

▪ It is almost impossible to imagine that the passenger pigeons’ population, which in the early 1800’s contained more individuals than all other North American birds combined, was reduced to just one individual, Martha, who died in captivity at the Cincinnati Zoo in 1914.

▪ Before their decimation, a single flock of passenger pigeons could have 2 billions birds or more, and there were multiple flocks of birds in the United States.

▪ The passenger pigeon was driven to extinction by uncontrolled commercial hunting for their meat

Animals that are extinct because of humans!!

▪ The Western Black Rhinoceros was sadly went extinct in 2011.

▪ The species was once widespread in central Africa, but the population began a steep decline due to poaching.

▪ Current rate of extinction - The current extinction rate is approximately 100 extinctions per million species per year, or 1,000 times higher than natural.

▪ About 150-200 species of plant, insect, bird and mammal become extinct every 24 hours.

Why it Matters

▪ Should it matter to humans that other life forms are disappearing? Many people think so. Human populations depend on plants and animals for much of their food, medicines, clothing, and shelter.

▪ Perhaps even more important, intact ecosystems perform many vital functions, like purifying the air, filtering harmful substances out of water, turning decayed matter into nutrients, preventing erosion and flooding, and moderating climate. It is not known how many species can be eliminated from an ecosystem without its functioning being impaired.

▪ What do you think is the most important reason?

Should we bring back extinct organisms?

▪ Thanks to new developments in genetic technology, DNA may eventually bring extinct animals back to life. Only species whose DNA is too old to be recovered, such as dinosaurs, are the ones to consider totally extinct, bodily and genetically.

▪ But why bring vanished creatures back to life? It will be expensive and difficult. It will take decades. It won’t always succeed. Why even try? What might happen?

Jurassic Park

▪ Video clip: https://www.youtube.com/watch?v=qUaFYzFFbBU

How do we know IF something can be brought back?

We need to know more…

▪ You will be given an article to read, “The Debate: should extinct species stay extinct?”.

▪ Read the article and annotate it –especially to mark key points or to add your own questions

▪ Once done reading, turn to your partner and fill out the pros/cons worksheet.

Once finished…

▪ Take a minute to think about whether you are for or against bringing extinct species back to life

▪ When the teacher tells you to, go sit on that side of the room

Let’s discuss!

▪ You may share out up to three times.

▪ Be ready to “back up” your claim or statement with what you have read