Does anyone really know?—It was 65 million years ago!!!!!
Could it have been “natural” extinction? Natural extinction happens when a species fails to adapt to the environment (or changes in the environment) as efficiently as other species and eventually dies off. May have played a role, but scientists think there was a more dramatic contributing cause...
Thought to Be Global Climate Change of Unknown Cause (External or Internal; Sudden or Gradual)
Mass Extinction When more than 50% (half) of all known, living species become extinct in a short period of time (less than 2 million years)
Is this just irrelevant ancient history? NO! ! ! ! ! ! ! !
Why it’s relevant: The mass extinction involving the dinosaurs was only one in a series of known mass extinctions. There have been others. Some scientists think we are on the verge of yet another in our lifetimes.
What do these species have in common with dinosaurs? They, too could become EXTINCT!
Species Group of organisms capable of interbreeding (reproducing) with each other but not with other groups.
Species at Risk— 2 types “Endangered Species”: Species that are at risk of becoming extinct in the near future throughout much or all of their habitat range. “Threatened Species”: Species that are at risk but not yet in as much danger as endangered species. They are likely to become endangered in the near future.
Notes About Endangered and Threatened Species NOT JUST ANIMAL SPECIES! Includes plant and insect species as well. Worldwide, there are at least 1832 endangered or threatened species. And that’s just the official list! Over 1,000 are found in the United States. About half the counties in the U.S. contain endangered or threatened species.
What’s the connection between endangered species and “biodiversity?”
Biodiversity is… Variety among all levels of life on Earth. The two main levels for thinking about biodiversity are the species level and the ecosystems level. We’ll discuss the current threats to biodiversity by first looking at species, then we’ll discuss ecosystems. The same threats affect both levels of biodiversity.
(Among other things) WE DO!! What threatens biodiversity today? Human civilization and economic activity put pressure on aspects of biodiversity. The present rate of extinction is believed to be much higher than can be explained totally by natural causes. We must be careful to balance our needs with those of other species.
Three major human-related threats to biodiversity Trade (and illegal poaching) Development/ Loss of Habitat Pollution
Threat One: Trade What is trade? Trade is traffic in goods, such as by gift, barter (swapping), or sale. People all over the world engage in trade, on the local, national, or global level. Sometimes when species are taken from the wild or from other settings to be traded, we refer to this as harvesting the species.
How do harvesting and trade affect species? Some species are hunted for their meat, their fur, or other parts of their body (such as elephants for their ivory). Some are sought as pets. Some of this trade is legal, but some is illegal (poaching). If too many species are hunted or harvested too quickly, the species population may shrink. Not enough young are born to become adults and make up for those being harvested. Other animals can be indirectly harmed in the process of other animals being hunted or harvested (such as dolphins caught in tuna nets).
What is Poaching? The illegal practice of trespassing on private or protected property (such as national parks or wildlife preserves) to hunt, fish, or steal game. Also includes illegally removing game, fish, plants, or parts of animals to trade illegally. Illegal hunting is a major problem for certain wildlife populations around the world. In some areas poaching is devastating wildlife and its ecosystems.
Elephant poaching is a problem in many countries. They are hunted mainly for their ivory tusks.
In some countries, such as India, tigers are poached for their skins, bones, and claws. These poachers were caught by Indian authorities.
Why poach? As species become more and more endangered, each remaining specimen becomes more and more valuable. Some people are willing to pay a lot of money to get rare goods associated with these species. This creates an incentive for people to hunt, or “take” the species, even though they are protected by law. The poachers want to make money from this, which usually is more than they could make at other jobs.
Regulating Poaching Many individual countries have enacted specific laws outlawing poaching of various species and their products. Some international laws have also been put in place to outlaw trade in endangered species. But the behavior is difficult to control. Sale of poached goods provides income for the poachers, who do not want to stop.
Some plants are illegally traded too! Agarwood, the fragrant wood produced by a species of the Asian Aquilaria tree family, may be over-exploited to commercial extinction due to over harvesting and illegal trade. Ocean plants are also sometimes illegally traded, which harms other species in their ecosystems
Threat Two: Development “Development” refers to processes that transform a place to make it suitable for commercial or residential purposes.
Destroying animal’s habitats Destroying some animals’ food sources (such as plants) Bringing pollution to previously clean areas Development can threaten biodiversity by:
How are the species of the Everglades threatened by development? 900 people move to Florida each day 39 million people vacation in Florida annually 12 million people spend the winter in Florida And all those people need…