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.
[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.]
- Introduce the major groups of plants, and the plant traits that provide a basis for their classification
- Introduce the major groups of animals, and the animal traits that provide a basis for their classification
In this exercise, it is assumed that you have learned about
phylogeny, and how to read tree diagrams such as cladograms
that represent phylogeny. Click here if
you would like to review this material before starting the
lab exercise.
Plants came from an ancestor that evolved in the water. The evolution of the land plants has involved successive adaptations to life on land. Different traits adapting plants to life on land reflect the phylogenetic relationships among the
major groups of land plants. These traits include the following:
- vascular
tissue: tissue that transports water throughout a plant.
Plants without vascular tissue rely on diffusion of water from
the environment into the plant's tissues to obtain required
moisture. Plants with vascular tissue can obtain water from the
ground, through roots, and then the vascular tissue transports it
to all the other tissues of the plant.
- pollen:
a tiny, powdery substance that produces sperm and that can be transported from plant to plant without water. Plants with pollen
do not require water in the environment to reproduce sexually;
plants without pollen do.
- seeds:
structures which contain and protect developing plant embryos from
drying out, and which may be dispersed over long distances.
Based on these characteristics, plants have been classified
into the major groups shown in the following phylogeny. To learn
the groups for which these different characteristics of plants
provide evidence, you can use the plant phylogeny shown here:
Instructions:
- Click on the name or picture of a plant group for
more details about this group.
- Click on one of the vertical lines that represents an ancestral
species to learn which of the characteristics
of plants provide evidence that the groups
shown as being descended from this ancestral species shared
an ancestor not shared by other groups.
The Phylogeny of Plants
index
Like plants, animals evolved in the water; some groups have
evolved to live on land, but others have not. Unlike plants, animals must obtain food, in the form of other organisms, from
their environment (plants, of course, obtain energy by way of
photosynthesis and can synthesize biological molecules using this energy and inorganic nutrients from the air and/or soil.) Animals
also differ from plants in that most animal species have a distinctive, determined shape into which they develop. To
illustrate this difference between plants and animals, think of
how a tree can grow branches in various directions, depending on
the light or wind or other environmental factors, but humans do
not grow variable numbers of arms and legs in any old direction -- we all develop the same shape with two arms and two legs. Many
of the characteristics that have evolved in animals, and reflect
their phylogenetic relationships, are related to either the way in
which they obtain and process food or their general shape and the
process through which they develop their shape.
These characteristics include:
- Whether or not the digestive
tract is
complete. The earliest animals had an incomplete
digestive tract; this means it had only one opening which
functioned both as a mouth to take food in and as an anus to get
rid of waste products. Later, a complete
digestive tract evolved; a complete digestive tract has a mouth
at one end and an anus at the other end, and allows more efficient
processing of food and wastes.
- Overall body
symmetry:
The earliest animals had what is called radial symmetry
during all phases of the life cycle. This means that
there are many planes through which one could divide an animal
into identical halves; animals with radial symmetry do not have a
well developed head at one end of the body. Later, some animals
evolved bilateral symmetry. Bilaterally
symmetric animals can be divided into mirror images along only
a single plane. Bilateral symmetry is generally associated with
development of a head at one end of the body.
- Whether or
not they develop a coelom , an
internal body cavity lined with tissue called mesoderm which is
separate from the skin layer of tissue (ectoderm) and from the
tissue of the digestive tract (endoderm.) The earliest animals
lacked a coelom; later in evolution some animals evolved it, and
it has allowed more specialization of internal organs than is
present in animals without it.
Based on such characteristics, animals have been classified into the major groups shown in the following phylogeny. To learn how
these characteristics provide evidence for this phylogeny, you
can use this phylogeny as follows:
Instructions:
- Click on the name or picture of an animal group
for more details about this group.
- Click on one of the vertical lines that represents an ancestral
species to learn which of the characteristics
of animals provide evidence that the groups
shown as being descended from this ancestral species shared
an ancestor not shared by other groups.
The Phylogeny of Animals
index
If you are interested in learning more about the phylogeny of
plants and animals, or about other forms of life, there are many
sites on the world-wide web where such information is available.
A few are listed here:
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. They also have information on how various
groups are studied, using information from everything from fossils to DNA.
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, including an exhibit on the origin and evolution of life.
The University of
Delaware Botanic Gardens
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.
index
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
