Welcome to the Biology 120 Plant and Animal Phylogeny Exercise!

Information for anyone who may have wandered here from outside of UTM:

This exercise is designed for students taking Biology 120 (the second term of introductory biology) at The Univerisity of Tennessee at Martin . This course is offered each term through the department of Biological Sciences and is designed to introduce areas of ecology, evolution, and organismic biology to biology majors and non-majors.

Goals of this exercise:

[Note that clicking on any of these goals will take you directly to the section most relevant to that goal. As you read through the exercise, you will from time to time have an opportunity to click on index ; if you do so, it will return you to this point.]

  1. Review phylogeny and phylogenetic trees
  2. Introduce the area of taxonomy
  3. Introduce the major groups of plants, and the plant traits that provide a basis for their classification
  4. Introduce the major groups of animals, and the animal traits that provide a basis for their classification
  5. Visit some "museums" on the world-wide web to obtain additional information and viewpoints on the phylogeny and classification of life

Phylogeny:

Remember that phylogeny refers to the evolutionary relationships among species. The process of evolution of more than one (usually two) new species from a pre-existing species is called speciation and can be represented as follows:

Reading tree diagrams of phylogeny:

Phylogenies are typically diagrammed as trees; the shape of these trees can vary, but all can be interpreted as follows. Lines with names associated with them refer to species or groups of species all more closely related to each other than to other groups on the tree. Following these lines back to the points where they join other lines leads to ancestral species to the named groups. Lines that lead back to the same line represent species that share a common ancestor.

Here are three phylogenetic trees; all represent the same pattern of phylogenetic relationship among the species shown. Be sure to study these until you can see that all are the same. In this exercise you will need to be able to interpret phylogenetic tree diagrams drawn by different people in different ways.

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Taxonomy:

Taxonomy is the name given to the study of classification of organisms based on their phylogenetic relationships. In making a phylogenetic classification, taxonomists name groups of organisms that are all close relatives of one another. There is some variation in the criteria taxonomists use for making classifications; here, we will only consider phylogenetic classifications , that is, classifications based purely on phylogenetic relationships among species.

Classification schemes are hierarchical in nature. Large groups containing many different species are divided into smaller more specific groups, each with fewer species. Each of these is divided into still smaller groups with still fewer species. These groupings reflect phylogenetic relationships. For example, all animals -- all the descendents of the species that was the ancestor to all mammals -- are placed together into one large group; within that group, more closely related animals are placed together into smaller groups, and so on.

There are seven traditional major levels in a classification scheme. Arranged from most general (the largest groups, containing many different species) to most specific (the smallest groups, containing, at the lowest level, only the members of a single species), these are: 

 
     Kingdom
       Phylum (in animals) or Division (in plants)
         Class
           Order
             Family
               Genus
                 Species
Every organism is placed into one of five kingdoms. These are the:
Kingdom Monera
Bacteria and cyanobacteria. Unicellular organisms that are prokaryotic , that is, do not have a nucleus surrounded by a nuclear membrane. The bacteria are mostly heterotrophic, that is, they cannot obtain energy from non-living forms and must eat other organisms, or their products, to obtain energy. The cyanobacteria are autotrophic, that is, they can convert energy from non-living forms into biologically useful energy (stored in the chemical bonds of biological molecules); cyanobacteria, like plants, accomplish this through the process of photosynthesis
Kingdom Protista
Unicellular organisms that are eukaryotic , that is, have a nucleus separated from the cytoplasm of the cell by a nuclear membrane. Some are plant-like in that they are autotrophic, while others are animal-like in that they are heterotrophic.
Kingdom Animalia
Animals. Multicellular organisms with cells that lack a cell wall. Many are capable of movement, or movement of some of their body parts, at some time of their life. Animals are heterotrophic , that is, they cannot obtain energy from non-living forms and must eat other organisms, or their products, to obtain energy.
Kingdom Plantae
Plants. Multicellular organisms with cells surrounded by a cell wall made of the carbohydrate cellulose . Plants are typically non-moving. They are autotrophic , that is, they can convert energy from non-living forms into biologically useful energy (stored in the chemical bonds of biological molecules); plants accomplish this through the process of photosynthesis , synthesis of energy-containing biological compounds by trapping light energy.
Kingdom Fungi
Mushrooms, yeasts, and other fungi. Multicellular organisms that are typically non-moving, have a cell surrounded by a cell wall, and are heterotrophic , that is, they cannot use energy from non-living forms and must consume other organisms, or their products, to obtain energy. Many are decomposers , that is, they obtain energy by breaking down molecules in dead, decaying organisms.

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Major groups of plants:

The plants have been traditionally classified based on two major kinds of characteristic:
The life cycle of plants
The plant life cycle is divided into two phases, the sporophyte phase, which is diploid, and the gametophyte phase, which is haploid. Individual sporophytes reproduce by producing haploid cells called spores through the process of meiosis . These spores develop into the haploid gametophytes. Gametophytes produce haploid gametes , that is, sperm or eggs; union of a sperm and an egg produces a zygote that develops into a new sporophyte, thus completing the life cycle. Different kinds of plant have different emphasis in the life cycle upon the sporophyte or gametophyte phase; in some groups, the gametophyte is large than and dominant to the sporophyte, while in others, the sporophyte is larger than and dominant to the gametophyte.
Adaptations to life on land
Plants evolved in the water; plants that have colonized the land show different degrees of adaptation to life on land, such as:

Based on these characteristics, plants have been classified into the major groups shown in the following phylogeny.

Instructions:

The Phylogeny of Plants

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Major groups of animals

Animals are all multicellular and develop through a process of embryonic development; they have traditionally been classified primarily on characteristics related to embryonic development. These characteristics include:

Based on such characteristics, animals have been classified into the major groups shown in the following phylogeny.

Instructions:

The Phylogeny of Animals

Note that the relationships between the protostome groups -- the Arthropoda, Annelida, and Mollusca -- are not clear. All three groups are shown here as coming from a common ancestor, but the characteristics we are using do not help us to determine whether arthropods are more related to annelids or molluscs, or whether annelids and molluscs are more related to each other than to the arthropods. A structural characteristic that was used traditionally to help determine relationships in this group was body segmentation, which is highly developed in both the annelids and the arthropods. There is, however, one group of molluscs that shows body segmentation, so it is not clear from this trait whether molluscs were originally segmented but then lost that trait or whether the segmented molluscs evolved segmentation independently from the annelids and arthropods. Because of this, we cannot tell based on segmentation what the relationships within this group are. Below, you will visit the University of California at Berkeley Museum of Paleontology and learn what phylogenies based on DNA, the genetic material, suggest about the relationships among these groups.

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Links to different museums on the world-wide web

The University of California at Berkeley Museum of Paleontology

The University of California at Berkeley Museum of Paleontology (UCMP) is a research museum with specimens of fossils of a wide diversity of organisms, including many plants and animals. Their world-wide exhibit includes information on the phylogeny and ecology of both modern and fossil organisms; you have already been refered to it in reference to several of the modern phyla. The phylogenies they present provide a way of studying whether phylogenies based on different kinds of character agree with each other, and how studying more than one character can help resolve some difficulties present if only one kind of character is studied. The phylogenies of plants and animals that you have studied in this exercise have been based primarily on structural characteristics or aspects of life history. Phylogenies presented at the UCMP are based on analysis of DNA, the genetic material. You should visit the UCMP exhibits and compare the phylogeny of animal phyla based on DNA to the phylogeny of animal phyla presented here based on traditional structural characteristics. Do the two phylogenies agree? Can the DNA based phylogeny provide information on the relationships between the Annelida, Mollusca, and Arthropoda (remember, these could not be fully understood based on the structural traits we examined). Also compare the DNA based plant phylogeny to the phylogeny of plant divisions presented here; again, determine whether they agree. Use the specific questions and information in the handout given to you by your laboratory instructor to help you address these questions; this handout will also note some differences in how groups are named. Be sure you have this handout as you proceed with this exercise.

Once you reach the UCMP introductory page, you will want to go to the On-line Exhibits. From there, go into the sections on phylogeny. The UCMP pages include links to information on how to best navigate through these pages; with their help, you should be able to find the phylogeny of animal phyla and the phylogeny of plant divisions without (much) trouble. When you are ready, click here to go to the University of California at Berkeley Museum of Paleontology.

The Field Museum of Natural History, Chicago

The Field Museum of Natural History, in Chicago, is one of the largest natural history museums in the country. In addition to having public exhibits on various aspects of both natural history (how organisms evolve and function in their environments) and human culture and history, the Field Museum is a research museum. This means that it maintains extensive collections of preserved specimens, including preserved whole plants and animals, skins, skeletons, leaves, and frozen tissues from which molecules such as DNA can be extracted. Researchers in many areas of biology from all over the world can visit the museum and take data from these preserved specimens; sometimes, if researchers are unable to visit the museums, specimens may be sent out to various parts of the world on loan, if they are needed for a specific research project.

The Field Museum has several virtual exhibits on the world-wide web. For this lab exercise, you will "visit" the field museum by way of the world-wide web, and tour their exhibits on the origin of life. These are fairly general, public exhibits that show images of what early environments and organisms apparently looked like, and provide some basic information on an important aspect of studying diversity that we have not yet examined -- using fossils to study the evolution and diversification of life. To do this, you will first "go to" the Field Museum by clicking on the blue highlighted "Field Museum" below. Once there, you will see a sign for "Exhibits" -- click on that. This should take you to introductions to various exhibits. Find the one called "LIFE OVER TIME." You will need to go through three parts of this exhibit: Life Before Dinosaurs, Dinosaurs!, and Teeth, Tusks, and Tarpits! Clicking on the blue highlighted words will start you into an exhibit; move through it by clicking on pictures of arrows or walking feet. Sometimes you will need to take side trips to learn more about specific topics; any time a word is highlighted in blue, clicking on it will take you to more information.

Your laboratory instructor will give you a list of questions to answer; you will need to answer these as you go through the exercise. If you have them, you are ready to click on the following to go to the Field Museum of Natural History, Chicago, Illinois.

The University of Delaware Botanic Gardens

NOTE: You do not have any questions to answer about the Delaware Botanic Gardens, but it's a nice place to visit

Botanic gardens are areas in which a variety of different plants may be grown to represent various aspects of botany. Some may reflect particular ecological systems, some reflect taxonomy, some reflect horticulture. The World-wide web display of the University of Deleware Botanic Gardens has a number of photographs of various plants and their key features (fruits, flowers, bark, leaves). The display includes information on where these plants will grow and other horticultural information. If you would like to visit and see what a nice botanical garden is like, you can go to the University of Deleware Botanic Gardens

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The world-wide web contains many more sites on the diversity of life, and much more on biology in general! Some biology-related web sites are listed on the home page of the University of Tennessee at Martin Department of Biological Sciences .

This page was developed by Rebecca Irwin. Links to other sites were last updated on: 11 November 1998.