lec 21- global ecology Flashcards
what is the estimated number of species on earth?
10 million
what are the major drives of biodiversity loss?
- exploitation
- invasive/exotic species
- Land modification (habitat loss)
- appropriation of fresh water
- nutrient pollution
- contaminant pollution
- ozone depletion
- infectious diseases
- climate warming/change
how do humans effect food webs?
by mass exploitation of foods and top predators such as whales it can result in cascading effects in trophic levels
what affects do humans have on the distribution of large animals like bears?
humans ruin their habitats and cause them to avoid them, changing there distribution and results in them having smaller territories
what are native, introduced, and invasive species?
native: live in the place of origin, indigenous (e.g. bears)
introduced: non-native, require human intervention to persist and live (e.g. cows)
invasive: introduced or other, pervasive to new environment (e.g. plants, frogs, birds)
what are invasive species?
are organisms introduced by humans into a new habitat, have a negative impact on local ecosystem
what are some ways invasive species are introduced?
from fish cages, invasive species can be picked up intentionally and dropped into a new environment (e.g. invasive crabs)
what is the pathway to become invasive?
transported to new area–> established in new area–> population increases and expand–> have a negative ecological or economical impact
what are the characteristics of an invasive species?
short generation time, freq. reproduction, large no. offspring, small size, can disperse easily, few predators, and multiple life stages
what causes forest loss?
human activities like agriculture, forestry, urbanization
how much habitable land is on earth and how much makes up agriculture?
71% is habitable and 46% of the 71% is agriculture
