Integrative Biology 335:
Systematics of Plants
Biodiversity
Announcements:
Today's lecture on biodiversity was to have been given by Dr. Ken Robertson of the Illinois Natural History Survey. Get better soon, Ken!
Lecture Assignment 5 is due Monday, May 4th. Lecture Assignment 6 is due Monday May 11th.
The final lecture exam is on Thursday, May 14th, from 8 to 11 AM in this room. This exam will be comprehensive, but with emphasis on the last third of the course. It will be worth 20% of your final grade. There is a sample final exam in the back of your Class Notes (pp. 269-284) and the exam will be similar in style to what you saw in Lecture Exam 2. If there is interest, there will be a final lecture exam review (time and place TBA).
Final lab exam on Tuesday, May 5th (stations in lab) and Wednesday, May 6th (slides in lecture). Your final lab exam will also be comprehensive, but again with emphasis on the last half of the course. There will be a lab review in your regular lab room on Sunday, May 3rd (time 2-5 PM) and I will review families in lecture on Monday, May 4th.
After our lectures conclude, access the General Course Announcements link on the course homepage to obtain any late-breaking class announcements.
Don't forget to complete an ICES teaching evaluation for this course! This year, this evaluation is web-based, and no doubt you would have already received email announcements from the Center for Teaching Excellence. Your comments are important!
Lastly, we present a list of families/subfamilies that you will have during your final lab and lecture exams. To obtain this PDF, click here.
Web Resources:
Some of the information presented below parallels that used in IB 100/101. This information was prepared by Prof. Downie many years ago when he was teaching in that course.
Objectives:
After studying this material you should be able to:
- Define the term biodiversity and explain how the three levels of biodiversity (genetic, species, and ecosystem) are related and dependent on one another.
- Define what a species is and discuss why this definition is important in knowing how many species there are.
- Have an idea how many species of flowering plant species have been described, how many may actually exist, and where in the world species richness is the greatest.
- Know approximately how many species of flowering plants occur natively in Illinois today, as well as how many species are endemic to Illinois.
- Explain how biodiversity is lost, how rapidly it is currently being lost, and some of the reasons why we might be concerned about this loss.
- Explain the role of systematics in studying biodiversity.
"How Systematics Works"
- Field botanists explore the world's ecosystems and collect herbarium specimens
- These specimens are examined and identified to known species (if indeed possible)
- New species are formally described, named, and published
- These names are eventually incorporated into identification manuals (or floras)
- Herbarium specimens that have been identified are then placed in herbaria
- Scientists study herbarium material and, when possible, living plants to understand how species, genera, and families are circumscribed and related to each other
- Molecular studies often use herbarium specimens by extracting DNA from them; phylogenies derived from molecular data can be used to answer all sorts of systematic and evolutionary questions.
For several hundred years now, botanists have explored the far regions of the world, as different parts became accessible, and collected herbarium specimens, which were sent back to herbaria; sometimes seeds were also collected and set back to botanical gardens. Botanical explorers were, and are, interested in collecting:
The scientific discipline of "taxonomy" or "systematics" grew out of the need to formally describe, name, and classify all the newly discovered species. The original goal of taxonomy was to catalog life on earth.
Taxonomy progresses with the gain of accumulated knowledge and advances in technology. Consequently, in the past 250 years, the science of taxonomy and systematics has grown and diversified. Today, it can be said, perhaps a bit simplistically, that there are two major branches in systematics:
- cataloging, that is the basic process of exploring, collecting herbarium specimens, and describing and naming new species and other taxa.
- studies that concentrate on inferring evolutionary histories within and among taxa across all hierarchical levels.
While also simplistic, most current research in the cataloging takes place at major botanical gardens, arboreta, and natural history museums, while most evolutionary work is concentrated at universities.
In this lecture, the emphasis is on the cataloging aspect of taxonomy and on the more general topic of BIODIVERSITY.
BIODIVERSITY = Biological Diversity
The world's living species and populations of organisms along with their associated habitats and ecological systems.
Biodiversity is defined at three levels:
- Genetic diversity
- Species diversity
- Ecosystem diversity
Simply put, biodiversity increases when new genetic variation is produced, a new species arises, or a novel ecosystem (or habitat) is formed.
Biodiversity decreases when genetic variation within a species decreases, a species becomes extinct, or an ecosystem (or habitat) is lost.
Biodiversity is a dynamic process, and what we see today is the product of hundreds of millions of years of evolutionary history.
Genetic Diversity:
.
Left: Of all the genes in humans, 10,000 are outwardly (visibly) expressed and vary from person to person. Right: Carrot diversity, by Philip W. Simon.
- The variety of genetic information contained in all of the individual plants, animals, and microorganisms in the world.
- It occurs within and between populations of the same species, as well as between species. Individuals belonging to the same species are usually not identical genetically.
- Differences in the amount and distribution of genetic variation within a single species can be attributed to the enormous variety and complexity of habitats, and the different ways organisms have adapted to these habitats.
- Genetic diversity can be measured using a variety of DNA and protein-based techniques to determine genotypic differences. It can also in part be catalogued based on differences in expressed, phenotypic traits.
Species Diversity:
- The variety of living species.
- The question "What is a species?" is very important, for it has implications on how many species there actually are. Many different definitions of species have been proposed:
- Morphological species concept: Plants that look alike are treated as the same species
- Biological species concept: Plants that are reproductively isolated from each other are treated as different species
- Genetic species concept: Species are defined by the amount of genetic distance between them
- Phylogenetic species concept: A group of common ancestry that is diagnosably distinct from other such groups. (This means that geographic forms of the same species should be treated as distinct species--they have evolved separately, have unique evolutionary histories, and are diagnosably distinct. As such, the PSC can inflate species numbers.)
Some examples from: Systematics Agenda 2000: Charting the Biosphere
| Group |
Number Described |
Estimated Total Species |
| Viruses |
5,000 |
about 500,000 |
| Bacteria |
4,000 |
400,000–3 million |
| Fungi |
70,000 |
1–1.5 million |
| Protozoans |
40,000 |
100,000 –200,000 |
| Algae |
40,000 |
200,000–10 million |
| Flowering plants |
250,000 |
300,000–500,000 |
| Vertebrates |
45,000 |
50,000 |
| Roundworms |
15,000 |
500,00–1 million |
| Mollusks |
70,000 |
200,000 |
| Crustaceans |
40,000 |
150,000 |
| Spiders and mites |
75,000 |
750,000–10 million |
| Insects |
950,000 |
8–100 million |
"Scientists have a better understanding of how many stars there are in the galaxy than how many species there are on Earth."
An estimated 1.4 million species have been described to date, and estimates for the total number of species vary from 2 to 100 million.
For additional information:
How many species of flowering plants are there?
|
Geographical Region |
Species of Flowering Plants |
|
World |
280,000 – 400,000 |
|
Brazil + Zaire + Indonesia |
125,000 |
|
United States (3,500,000 miles2)* |
18,000 |
|
Panama (34,000 miles2) |
7,123 |
|
Illinois (56,400 miles2) |
2,000 |
|
* Includes Alaska, Hawaii, and Puerto Rico |
|
- There are over 280,000 species of angiosperms described from throughout the world, with the total number of extant species probably reaching 400,000 by some counts.
- The number of angiosperm families is well over 400.
- A recent estimate of the number of flowering plant species arrived at a figure of 422,000. [No ref. citation, but numerous webpages cite this number]
- Approx. half of the world's angiosperm species are found in three tropical countries: Brazil, Zaire and Indonesia. For comparisons, 18,000 species are found in the US (includes Hawaii and Puerto Rico) and 2,000 occur in Illinois.
Species diversity is not evenly distributed across the globe. In general, species richness is concentrated in equatorial regions (i.e., tropical rainforests) and decreases as one moves to the poles (or increases in altitude). Forty to fifty percent of all species are found in wet tropical rainforests, a region that comprises only 2% of the Earth's land surface.
|
Location and Area |
Number of Tree Species |
|
Borneo, 10 x 2.5 acre plots |
700 |
|
Southeastern Asia, 2.5 acre plots |
120 – 200 |
|
Peru, 2.5 acres |
300 |
|
United States (3,400,000 miles2)* |
680 |
|
Illinois (56,400 miles2) |
137 |
|
[U of I Quad is 9 acres] |
|
|
* Includes Alaska |
|
How many species of plants occur in Illinois?
|
Group |
Taxa |
T & E |
Extirpated |
Extinct |
|
Bryophytes |
506 |
|
2 |
|
|
Club mosses |
12 |
3 |
1 |
|
|
Horsetails |
12 |
3 |
1 |
|
|
Ferns |
75 |
13 |
2 |
|
|
Conifers |
14 |
7 |
|
|
|
Flowering Plants |
1,955 |
329 |
53 |
1 |
|
Total |
2,574 |
355 |
59 |
1 |
Approximately 2,000 species of flowering plants occur natively in Illinois today.
Only two species of flowering plants are endemic to Illinois; one of these is now extinct.
.
Left: Iliamna remota. Right: Thismia americana.
Ecosystem (Habitat) Diversity:
- The variety of habitats, biological communities, and ecological processes occurring within and between each type of ecosystem.
- Ecological processes, such as water and nutrient cycling, energy flow, succession, predation, competition, mutualism, parasitism, primary production, decomposition of organic matter, soil rehabilitation, pest and disease regulation, water quality, and pollination/dispersal mechanisms are maintained by a wide range of biologically diverse populations in natural ecosystems.
- An ecosystem is a community of organisms and their physical environment interacting together. An ecosystem can cover a large area, such as a whole forest, or a small area, such as a pond.
- Ecosystem diversity is a precondition for genetic and species diversity.
The natural community classification system used in Illinois
Reduction of Biological Diversity
- Species Loss (Extinction):
- In the geologic record, five mass extinctions have re-set the level of biodiversity on earth
- Currently, we are in a biodiversity crisis, the sixth and fastest mass extinction in Earth's history.
- The rate of species extinction is 1,000–10,000 times higher now than at any time before
humans evolved.
- In Illinois, 329 species of flowering plants are threatened or endangered.
- Population Loss (Loss of genetic variation):
- The decline in numbers and sizes of populations
- Lack of variety in mate selection and potential for inbreeding
- Habitat Loss:
- Deforestation. About 60% of all the tropical rainforests which existed 100 years ago are now gone. Now, 1–2% of the remaining tropical forests are removed each year. This is equivalent to losing an area the size of Florida each year! This translates to about 2.4 acres (1 hectare) per second, equivalent to two football fields (or 149 acres per minute or an area larger than NYC every day). If deforestation continues are current rates, it is estimated that all tropical rainforests will be destroyed by the year 2030.
- Also pollution and development causes habitat loss.
- Habitat loss directly impacts species diversity and genetic diversity.
Fragmentation of once continuous habitats into small remnants. Illinois once had 22 million acres of prairie (60% of Illinois). Now, only 2200 acres of high quality prairie exists (less than 1/100 of 1%).
Efforts to Preserve Biodiversity
There are many efforts to help preserve biodiversity, from local grass root organizations to international scale projects. Illinois is a leader because we have so few natural areas remaining.
Inventorying and Cataloging
- There is considerable work going on in this area. For example, see the research projects being carried out at the Missouri Botanical Garden.
- Today, most new species are discovered in tropical regions, but still there are "botanical surprises" to be found in the United States! One example is Neviusia cliftonii, Shasta snow-wreath.
- The All Species Foundation, which has a goal to "the complete inventory of all species of life on Earth within the next 25 years — a human generation. "
Biodiversity "Hotspots"
"The most remarkable places on Earth are also the most threatened, and many of them have been reduced to less than 10 percent of their original vegetation. These are the Hotspots: the 25 richest and most threatened reservoirs of plant and animal life on Earth. Hotspots are one of CI's main areas of focus for biodiversity conservation."
Efforts in Illinois
What are the benefits of preserving biodiversity?
- Pharmaceuticals
- 80% of people in less-developed countries rely heavily or entirely on drugs derived from natural sources
- More than 20,000 species have been used for medicinal purposes
- 41% of our prescription drugs have their active ingredients derived from living organisms
- 70% of promising anti-cancer drugs come from rain forest plants
- Relatively few flowering plants have been examined for their medicinal properties
- Food
- 30,000 plant species have edible parts; 7,000 species are grown and used as food; 20 species feed 90% of the world; just 3 species are major world-wide staples (rice, wheat and corn)
- Many underutilized food crops have the potential to become important in the future
- Wood and other biological products
- Biofuels, ethanol, new hybrids and varieties of ornamental plants, fibers, adhesives, natural rubber, etc.
- Genetic resources
- Land races (vs. modern, cultivated races) are diverse genetically and are important to augment the narrow genetic base of established food crops
- Ecosystem level benefits
- Protection of water resources, soil formation and protection, pollution breakdown and absorption, recovery from disturbances, etc.
- Ethical, Cultural, Historical
- Who are we to decide on the value of a species or an ecosystem?
For numerous other examples (and references), access the IB 100/101 Biodiversity lecture webpage
The importance of systematics in studying biodiversity
Much of our knowledge of biodiversity comes from the basic activities of systematic biologists, namely:
- the inventorying of known species from the world's ecosystems
- the discovery, description and naming of new species
- the determination of their characteristics and evolutionary relationships to other species
- the understanding of how species arise
- the organization of this knowledge into classification systems
Phylogenetic classification systems are powerful predictive tools that help us understand, maintain, and effectively utilize this great biological wealth.
And finally ...
"When you take a flower in your hand and really look at it, it's your world for the moment. I want to give that world to someone else. Most people in the city rush around so, they have no time to look at a flower. I want them to see it whether they want to or not."
Georgia O'Keeffe, New York Post, May 16, 1946.
This is our last formal lecture! We hope that you've enjoyed the course, and we would like to think that next time you travel, eat, or simply observe flowers in passing, you'll have a whole new appreciation of the plant life around you.
Click here to get home!
Species diversity is not evenly distributed across the globe. In general, species richness is concentrated in equatorial regions (i.e., tropical rainforests) and decreases as one moves to the poles (or increases in altitude). Forty to fifty percent of all species are found in wet tropical rainforests, a region that comprises only 2% of the Earth's land surface.
