Download How Many Species are There

Biology
Ch 14
NAME____________________
How Many Species are There?
Species are the fundamental unit of biodiversity, but, of all the tens of millions
of species that have existed on the earth, only a comparatively small percentage
have been studied in detail. Some species have been well studied, such as many
large mammal, butterfly, bird, plant, and insect species. But very little is known
about the biology and distribution of vast numbers of species groups such as
arthropods, fungi, and nematodes. In the past decade, scientists have discovered
species in areas that were previously inaccessible, such as the tube worms in
deep sea thermal vents and discovered new species even in relatively well
populated areas.
There have been a number of efforts to estimate the number of species that are known and have
been described. This is a challenging job because there are no central registries for species, and
no one database. Often species that have been described by scientists in one geographical site,
are also recorded and described by scientists at another. It takes time and research for biologists
to recognize these redundancies. In addition, scientists have different opinions about what
constitutes a species or a subspecies. Biologists define a species as a population that interbreeds
under natural conditions. However, there are ambiguities in this definition that add to the
difficulty of enumerating species, even those that have already been discovered.
The United Nations Environment Program's Global Biodiversity Assessment is often cited, which
estimates the number of described species at approximately 1.75
million. One study done by prominent biologist E.O. Wilson
and others estimate known species at approximately 1.4 million,
while another study estimates the number at approximately 1.5
million.
There are also differences in how organisms are categorized.
For example, for many discoveries, scientists must determine
whether is it a species or a subspecies. It is an easier task to
classify mammals and plants, but consider the difficulties of classifying bacteria. Very few
bacteria species have been given a scientific name. One Norwegian study found between 4000
and 5000 bacterial species in a single gram of soil. A single square
meter of "tropical grasslands can hold 32 million nematodes."
Biodiversity is not evenly distributed across species or across
regions. Over half of all described species are insects, including
approximately 300,000 known beetles, a fact which led biologist J.
B. S. Haldane to remark that God has "an inordinate fondness for
beetles."
Considering the difficulties in assessing the number of species
already known, imagine the difficulties of estimating the total number of species on the planet.
Compounding the problem is the fact that diversity is not evenly distributed across the planet.
Seventy percent of the world's species occur in only 12 countries: Australia, Brazil, China,
Columbia, Ecuador, India, Indonesia, Madagascar, Mexico, Peru, and Zaire. The tropical rain
forests are believed to contain more than half the number of species on Earth.
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Source: Environmental Literacy Council http://www.enviroliteracy.org/
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BIODIVERSITY IN CALIFORNIA
Two important facts about California:
California is the most biologically diverse state in the union, with 40,000 species and more
federally listed species than any other mainland state.
California's population is expected to grow from 32 million to 49 million by the year 2025.
The high biological significance of Southern California was also highlighted in a recent study of
the geographic distribution of endangered species in the U.S. (Dobson et al., Science 275; 550).
The maps show the number of listed species in each county for several groups of organisms. For
plants especially, Southern California turns out to be a "hot spot" of threatened biodiversity. The
other hot spots are Hawaii, the southeastern coastal states, and southern Appalachia. As
expected, in most cases, hot spots occur where the ranges of many endemic species overlap with
intensive urbanization and agriculture.
The predicted population growth means there will inevitably be increasing pressure on our
natural resources in the coming decades. California has an urgent need to establish programs for
cataloguing and preserving biodiversity. Fortunately the state is taking this task fairly seriously.
In fact, a recent survey by the organization Defenders of Wildlife concluded that California has
the nation's best biodiversity policies and programs. This was mainly in response to the
development of Natural Communities Conservation Planning (see later lecture) and partly to the
establishment of the California Biodiversity Council, whose role is to "develop guiding
principles and policies, design a statewide strategy to conserve biological diversity, and
coordinate implementation of this strategy through regional and local institutions".
The California Resources Agency is responsible for the conservation, enhancement, and
management of California's natural and cultural resources, including land, water, wildlife, parks,
minerals, and historic sites. One of their programs is the California Environmental Resources
Evaluation System (CERES), an information system designed to "facilitate access to a variety of
electronic data describing California's rich and diverse environments".
In California, the California Department of Fish and Game (DFG) has the responsibility for
identifying the most significant natural areas in the State.
Significant Natural Areas are those sites which meet at least one of the following criteria.
1. Areas supporting extremely rare species or natural communities;
2.Areas supporting associations or concentrations of rare species or communities;
3.Areas exhibiting representative examples of common or rare communities;
4.Areas of high species-richness or habitat-richness.
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The DFG has also produced an on-line map of habitat types in California. They also have an
active program of documenting California's wildlife and endangered species. Visit their
California Wildlife Habitat Relationships page.
THE CONVENTION ON BIOLOGICAL DIVERSITY
The Convention on Biological Diversity (CBD) was signed by over 150 governments at the 1992
Earth Summit in Rio de Janeiro, and became effective as international law in December 1993. It
is the first international agreement committing governments to comprehensive protection of the
Earth's biological resources. To date, 193 parties had ratified the agreement.
The CBD has three overall goals:
1. the conservation of biological diversity,
2. the sustainable use of its components, and
3. the fair and equitable distribution of benefits derived from "genetic resources".
By signing the CBD, participating governments agree to carry out various measures to conserve
biodiversity. The measures include (among other things):
1. to create national plans for protection of biodiversity.
2. to identify ecosystems, species and genomes important for conservation and sustainable
use of biodiversity
3. to monitor biological diversity and any factors that might have impacts on it.
4. to establish a system of protected areas
5. to manage biological resources to ensure conservation and sustainable use
6. to rehabilitate and restore ecosystems
7. to take measures for ex situ conservation.
The CBD has also published a useful Global Biodiversity Outlook.
The CBD also includes agreements for using biological diversity. And governments must provide for
"fair sharing" of the benefits derived from genetic resources (i.e. compensation for its use or transfer of
technology derived from genetic resources).
In 2010, Parties to the CBD adopted the Strategic Plan for Biodiversity 2011–2020, a ten-year
framework for action by all countries and stakeholders to safeguard biodiversity and the benefits it
provides to people.
Sources:
http://darwin.bio.uci.edu/~sustain/bio65/lec06/b65lec06.htm#BIODIVERSITY%20IN%20CALIFORNIA
http://www.cbd.int/undb/learn/factsheet/cbd/undb-factsheet-cbd-en.pdf
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Biology
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QUESTIONS: You will need to read the above article as well as 14.1 and 14.2 to answer the
following questions. All questions must be answered USING COMPLETE SENTENCES.
1. Define species using the article definition. Then define the term biological species using your
textbook. Are there any differences between these two definitions? Explain.
2. How many different species are there in the world? Why is it so difficult to come up with a
number?
3. How many species are found in California? Why do you think CA has a higher number of
species than any other state in the contiguous US?
4. Explain in your own words the purpose and goals of CBD.
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5. Define the following words.
Phylogeny –
Convergent evolution –
Analogous characters –
Cladistics –
Ancestral character –
Derived character -
Taxonomy –
Binomial nomenclature -
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