Complete question:
Three types of threats to biodiversity are:
habitat loss and fragmentation the introduction of exotic, or non-native, species overexploitation, or overharvesting.
Determine the type of threat that each of the following statements describes.
1. a wetland is drained to make room for a housing development.
2. south american rodents called nutria eat wetland plants and cause bank erosion in the united states.
3. some fishing nets damage the seafloor.
4. melaleuca trees from australia displace native wetland vegetation in florida.
5. small rainforest remnants have less diversity than larger rainforest remnants.
6. cod are caught faster than they can reproduce.
7. florida panthers were geographically cut off from other panthers about 100 years ago.
8. wild american ginseng populations have declined as a result of increased demand for the roots.
Answer:
1. a wetland is drained to make room for a housing development.--> <em>habitat loss and fragmentation</em>
2. south american rodents called nutria eat wetland plants and cause bank erosion in the united states.--> <em>introduction of exotic, or non-native, species</em>
3. some fishing nets damage the seafloor.
--> overexploitation, or overharvesting
4. melaleuca trees from australia displace native wetland vegetation in florida.
--> introduction of exotic, or non-native, species
5. small rainforest remnants have less diversity than larger rainforest remnants.
-->habitat loss and fragmentation
6. cod are caught faster than they can reproduce.
--> overexploitation, or overharvesting
7. florida panthers were geographically cut off from other panthers about 100 years ago.
--> habitat loss and fragmentation
8. wild american ginseng populations have declined as a result of increased demand for the roots.--> <em>overexploitation, or overharvesting</em>
Explanation:
- Habitat loss and fragmentation. Refers to the effects of human activities and their expansion in space as populations get bigger and economic activities increase. The expansion of agriculture and cattle industry limits are one of the most important activities responsible for habitat fragmentation. In the last few years, the real estate industry took an important role in habitat fragmentation and alteration. Following this idea of "progress", government and private enterprises alter the natural and pristine environment and open new areas destined for different activities, in most cases contaminating the area. A progressive and continuous change occurs in the natural environment. Following the reduction of habitat, there is a decrease in the size of populations of the affected native species. The species richness decreases, and there is no connection or paths among isolated areas.
- The introduction of exotic, or non-native, species. Refers to biological invasions. New species that establish in a new area far or out of their original distribution range. These species might be considered exotic or invasive, according to their reproductive rate, population growth, and interaction with native species. Once established, the introduced species expand their distribution from the first invaded spot and overgrows. It is very common for these species to start new populations in the new area, where they have less environmental pressure and better conditions than in their origin area -fewer predators, more resources, better nitches-, and these factors favor their establishment. As they expand, they compete with other species for resources. In the case of plants, these resources are water, place, radiation, exposure, among others. Species are considered to be invasive because of their reproductive rate, population growth, and interaction with native species, which provokes huge damages in the native ecosystems. Biologic invasions are natural processes, that occur in small groups of individuals that can expand to other ecosystems, and the appearing or despairing of barriers promotes their expansion. But these biologic invasions have accelerated by human beings, referring to this as "human-assisted invasions". These are the cases in which men transport species from one place to the other for different uses or purposes. It is very common for these species to scape and start new populations in the new area, where they have less environmental pressure -fewer predators, more resources, better nitches- than in their origin area, which favors their establishment.
- Overexploitation, or overharvesting. Refers to the unlimited use of resources. People, acting by their own needs or interests, may exceed the harvesting, affecting the resource population and, therefore, other users. Overexploitation might lead to the extinction of the species that are taken in excess and to the decrease in the size of other organism´s populations that also depend on those resources.
