Chapter 43 Bio

conservation biology
Someone who has a global perspective to the changes happening across earth and focusing on a discipline that seeks to preserve life.

three main components of biodiversity
genetic diversity, species diversity, and ecosystem diversity

genetic diversity
comprises not only the individual genetic variation within a population but also the genetic variation between populations that is often associated with adaption to local conditions, Impact if diversity is decreased: If a species becomes extinct then a species may have lost some of the generic diversity that makes microevolution possible. This erosion of genetic diversity in turn reduces the adaptive potential of the species.

species diversity
the variety of species in an ecosystem or across the biosphere, impact if diversity is decreased: As more species are lost to extinction species diversity decreases.

ecosystem diversity
the variety of ecosystems in the biosphere (Variety of habitats, living communities, and ecological processes in the living world), impact if diversity is decreased: Because of the many interactions between populations of different species in an ecosystem the local extinction of one species in an ecosystem can have a negative impact on other species in the ecosystem.

endangered species
is one that is in danger of extinction throughout all or significant portion of its range.

threatened species
are those considered likely to become endangered in the near future.

habitat loss
– Human alteration of habitat is the single greatest threat to BD. Habitat loss is brought on by agriculture, urban development, forestry, mining, and pollution. Also global climate change.
– – When no alternative habitat is available or a species is unable to move habitat loss may mean extinction.
– – The IUCN implicates destruction of physical habitat for 73% of the species that have become extinct, endangered, vulnerable, or rare in the last few hundred years.
– – Habitat fragmentation leads to species loss because the smaller population in habitat fragments have a higher probability of local extinction.

Introduced species
– Introduced species (exotic species) are those that humans move intentionally or accidentally from the species native locations to new geographic regions (spreads easier now with fast travel like on ships or airplanes)
– These introduced species are now free from predators, parasites, and pathogens that limit their population in their native habitats. So such transplanted species may spread rapidly through a new region.
– Some introduced species disrupt their new community often by preying on native organisms or outcompeting them for resources.
– Overall: introduced species are a worldwide problem contributing to 40% of the extinctions recorded since 1750 and costing billions of dollars each year in damage and control efforts (There are more than 50,000 introduced species in the US alone).

Overharvesting refers generally to the harvesting of wild organisms at rates exceeding the ability of their population to rebound (species with restricted habitats such as small islands are particularly vulnerable to overharvesting) (also large organism with low reproductive rates like elephants, whales, and rhinoceros are susceptible to overharvesting).

What do conservation biologists who adopt the small-population approach study?
the process that cause extinctions once population sizes have been reduced.

Explain what an extinction vortex is, and describe one field study that supports this idea.
Is a downward population spiral in which inbreeding and genetic drift combine to cause a small population to shrink and (unless the spiral is reversed) become extinct (A small population is vulnerable to inbreeding and genetic drift, which draw the population down an extinction vortex toward smaller and smaller population size until no individuals survive.), conservation biologist study this idea

Why is genetic variation the key issue in the small-population approach?
Key factor driving the extinction vortex is the loss of the genetic variation that enables evolutionary responses to environmental change such as the appearance of new strains of pathogens. Both inbreeding and genetic drift can cause a loss of genetic variation and their effects become more harmful as a population shrinks (inbreeding often reduces fitness because offspring are more likely to be homozygous for harmful recessive traits).

(Genetic variation is a key issue with the small-population approach because it enables evolutionary responses to environmental change, such as the appearance of new strains of pathogens)

On what type of population does the declining-population model focus?
The declining population model/ approach focuses on threatened and endangered populations that show a downward trend (even if the population is far above minimum viable population).

What is the emphasis for study in the declining-population model?
The declining population approach emphasizes the environmental factors that caused a population decline in the first place (like if an area is deforested and a species rely on trees to live then they will become locally extinct whether or not they retain genetic variation).

small pop approach focuses on smallness itself and loss of genetic variation/ diversity as the cause of extinction

Describe how the increase in cowbirds is related to forest fragmentation
Cowbirds is an edge adapted species. Their populations are growing where forests are being cut and fragmented which creates more edge habitat and open land.

What are potential positive and negative effects of movement corridors?
Positive: Movement corridors promote dispersal and reduce inbreeding in declining populations. In fact corridors have been shown to increase the exchange of individuals among populations of many organisms (including butterflies, voles, and aquatic plants). Also corridors are especially important to species that migrate between different habitats seasonally.

Negative: Corridors can be harmful, for example by allowing the spread of disease (ex: Habitat corridors can facilitate the movement of disease carrying ticks)

movement corridors
is a narrow strip or series of small clumps of habitat connecting otherwise isolated patches, It is important in conserving biodiversity.

Explain the concept behind a zoned reserve
A zoned reserve is an extensive region that includes relatively undisturbed areas surrounded by areas that have been changed by human activity and are used for economic gain. The key challenge of the zoned reserve approach is to develop a social and economic climate in the surrounding lands that is compatible with the long term viability of the protected cores (the surrounding areas/ the buffer zones serve against further intrusion into the undisturbed area while still supporting human activities but prevents regulations extensive alterations likely to harm the protected zone).

How has agriculture affected nitrogen cycling? What are some negative consequences of nutrient enrichment?
After vegetation is cleared from an area the existing reserve on nutrients in the soil is only available for a brief time (since the substantial fraction of these nutrients is exported from the area in crop biomass) and so farmers add fertilizer to increase crop yield. Nitrogen is the main nutrient element lost through agriculture so applied fertilizers make up for the loss of usable nitrogen from agricultural system.
Nutrient enrichment becomes a problem when the nutrient level in an ecosystem exceeds the critical load which is the amount of added nutrient that can be absorbed by plants without damaging ecosystem integrity. When nitrogenous minerals in the soil exceed the critical load eventually the nitrogen leaches into groundwater or run off into freshwater and marine ecosystems. It sometimes can contaminating water supplies, kill fish, and make the water unsafe to drink. Another big consequence that happens is that the nitrogen from agricultural runoff and sewage drain into the Atlantic Ocean and Mississippi River. The Mississippi River carries the nitrogen pollution to the gulf of Mexico which flues a phytoplankton bloom each summer.. When the phytoplankton die their decomposition by oxygen using organism creates an extensive dead zone of low oxygen concentration along the Gulf Coast. Fish and marine animals disappear from the dead zone and some of the most economically important waters in the United States is damaged.

Explain the process of biological magnification
A process in which retained substances become more concentrated at each higher trophic level in a food chain

What is meant by the greenhouse effect? What would life on Earth be like without this effect?
The warming of Earth due to the atmospheric accumulation of carbon dioxide and certain other gases which absorb reflected infrared radiation and reradiate some of its back toward Earth. Without this effect the average air temperature at the Earth’s surface would be a frigid -18 C (-0.4 F) and most life would not exist

What is contributing to the great increase in atmospheric carbon dioxide? What are potential effects of this increase?
The thing contributing to the increase in CO2 is the burning of fossil fuel and human activity.
The effects of this increase is that the average global temperature will increase with increasing CO2. This warming would also then alter the geographic distribution of precipitation which likely making agricultural areas of the central United States much drier. Also it will cause the snow to melt and decreasing habitats for polar bears, seals, and seabirds. Higher temperatures also increase the likelihood of fires.

Summarize human population growth since 1650
(increased relatively slowly until about 1650) at which time approximately 500 million people inhabited Earth. Our population doubled to 1 billion within the next two centuries, doubled again to 2 billion by 1930, and doubled still again by 1975 to more than 4 billion. The global population is now more than 6.8 billion people and is increasing by about 79 million each year. Currently the population grows by more than 200,000 people each day

What is demographic transition? In demographic transition which falls first, birth or death rates?
the movement from high birth and death rates to low birth and death rates, death rates fall first

Why do infant mortality and life expectancy vary so greatly between certain countries?
The growth rates of individual nations vary with their degree of industrialization. In industrialized nations populations are near equilibrium with growth rates of about 0.1% per year and reproductive rates near the replacement level. In counties such as Canada the total reproductive rates are below replacement. Also life expectancy is varied due to diseases and voluntary population control

sustainable developement
is economic development that meets the needs of people today without limiting the ability of future generations to meet their need

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