Dawn of agriculture as the rise of human domination.
Where humans have colonized new areas are also associated with decline of large mammals.
Climate change, hunting and ecological explanations for the extinction of large mammals. Dung as the most recent proxy indicator that contributed to large mammalian decline.
Clovis people came over the straights. Humans almost certainly played a pivitol if not a primary role in contributing to the extinction of megafauna.
Humans are causing a wave of extinction that will result in a ¼ loss of the species during our lifetime.
We can think of a number of species that we have hunted to extinction through over-exploitation.
‘silent forests” of central/west Africa – little remaining wildlife
Bush hog (left, top center), some kinda rodent?
Hunting for value, meat, ivory.
What makes it a good and bad invader? It’s utility and usefulness to us. The Mississippi river was not originally connected to the great lake but the ship canal built in Chicago now connects them. The more disturbed they are the more they jump. They poisoned the entire Chicago Canal in order to make sure that the asian carp don’t make it into the great lakes.
Zebra mussels eat all of the algae out of the pelagic zone of the food web.
There is little doubt that the sea lamprey was primarily responsible for decline of lake trout in upper Great Lakes (Coble et al. 1990). This is evidenced by the timing of the collapse, coincidence of wounds and scars, simultaneous collapse in unfished bays, and continued decline after fishing had fallen to low levels. Detailed analysis of catch and effort data provided no support for over-fishing as the cause of declines, except in Lake Superior.
The gypsy moth arrived in the U.S. in the early 1900s, and in Michigan in the 1950s. With few natural enemies, it devours the leaves of forest trees. Although some defoliation is tolerable, if in two successive years and coupled with a drought, trees can be killed.
Are all invasive species equally talented. Does only one pregnant silver carp have to get past the chicago fence? If the community is already full (niche’s occupied) it does make it harder to survive. If the fish do get through the fence it is really hard to say what the impact will be in the long term.
Study of how many invasive attempts were made and how many of those were successful. There are speicific factors which predict the likelyhood of the an invasive species surviving.
Invasion is not just one step. It is a series of steps that have to occur in order for the invasion to be successful. Even once they are there it doesn’t mean they will stay.
Some species are extremely well adapted at invading a new community.
It would be misleading to add up the areas left. They are weaker and more vulnerable because they exist as isolated patches.
You can find literature about the number of species estimate to go extinct relative to climate change. RL designates the ‘range limit’. We can see the southern range limit of a given species. The challenge of place based conservation strategies is that as the climate changes reserves in certain areas will no longer be able to support species that we value. What we have now is a series of places that we treasure. They are about 12% of the earth’s surface today. It’s not clear what you can do to adapt these kinds of stragies.
There is not a whole lot of evidence for domino effects, though they do exist. Prarie dogs were once abundant, but have been hunted and poisoned. The black footed ferret, which depends on the prairie dogs has suffered. The theory of domino effects is probably overblown.
How could we estimate the rate of extinction caused by anthropogenic extinctions?
We can estimate the # of species: 2 million
We can estimate the rate of habitat loss.
We can estimate the species- area relationship to estimate species loss.
“Distant past” refers to average extinction rates as calculated from the fossil record. “Recent past” refers to extinction rates calculated from known extinctions of species (lower estimate) or known extinctions plus “possibly extinct” species (upper bound). A species is considered to be “possibly extinct” if it is believed to be extinct by experts but extensive surveys have not yet been undertaken to confirm its disappearance. “Future” extinctions are model-derived estimates using a variety of techniques, including species-area models, rates at which species are shifting to increasingly more threatened categories, extinction probabilities associated with the IUCN categories of threat, impacts of projected habitat loss on species currently threatened with habitat loss, and correlation of species loss with energy consumption.
A 10 times bigger space has about twice as many species.
With a certain rate of habitat loss we will have a corresponding loss of species.
This statistic is driven solely by biodiversity and habitat loss. It doesn’t take into account climate change.
This is a main topic in the theory of conservation biology. 12% means that 88% of the world’s surface is not protected. Michigan has unusually large areas of biodiversity areas. However, just saying something is a protected area does not tell you how or whether biodiversity is actually being protected there.
Wikipedia says: There are over 108,000 protected areas in the world with more added daily, representing a total area of 19,300,000 km2 (7,500,000 sq mi), or over 13 percent of the world's land surface area,
It’s important to distributed protected areas according to ecosystem type. We especially use GIS to find areas that might be missing in the protected network. How big of a reserve do you need? What if it is the African Savanna? Biggger may be better but how big.
Bigger area = increased populations of herbivores and carnivores. If the park is too small you won’t have any large carnivores at all. Newmark – each dot is a park in the US. The larger the park the lower the number of extinctions the park experienced over the long term. Once you parcel out part of the park it has a significant impact on the animal population of the park. Where, how many, connectivity are also very important.