An Evolutionary and Ecological
The field of Zoology is the study of
It is a very broad field with many
An understanding of evolutionary
processes is very important in zoology
because evolution explains the family
relationships among animals and how the
great variety of animals arose.
An understanding of ecological principles
is very important in zoology because it
helps zoologists to understand the
interrelationships among individual
animals and groups of animals.
Understanding ecological principles also
helps zoologists to understand how
human interference threatens animal
populations and the human environment.
Plainly stated, Zoology is the study of
One of the broadest fields in science due
to the immense variety of animals.
Ex. 20,000 species of described bony fish
Ex. 300,000 species of described beetles
Most zoologists specialize in one or more
They may study particular functional,
structural, or ecological aspects of one or
more animal groups or they may choose
to specialize in a particular group of
Examples of Specializations in Zoology
Anatomy Study of the structure of entire organisms and their parts
Cytology Study of the structure and function of cells
Ecology Study of the interaction of organisms with their environment
Embryology Study of the development of an animal from the fertilized egg to birth of hatching
Genetics Study of the mechanisms of transmission of traits from parents to offspring
Histology Study of tissues
Molecular biology Study of subcellular details of structure and function
Parisitology Study of animals that live in or on other organisms at the expense of their host
Physiology Study of the function of organisms and their parts
Systematics Study of the classification of, and the evolutionary interrelationship among, animal groups
Examples of specializations in Zoology by taxonomic categories
Entomology Study of insects
Herpetology Study of amphibians and reptiles
Ichthyology Study of fishes
Mammalogy Study of mammals
Ornithology Study of birds
Protozoology Study of protozoans
Zoology: An Evolutionary
Organic evolution is change in the genetic
makeup of populations of organisms over time.
It is the source of animal diversity, and it
explains family relationships within family
Charles Darwin published convincing evidence
of evolution in 1859 and proposed a
mechanism that could explain evolutionary
change. Since that time, many scientists have
become convinced that evolution occurs.
Structure and Function
Understanding how the diversity of
animal structure and function arose is
one of the many challenges faced by
For example, lets take a look at the
cichlid scale eaters of Africa.
As you may have guessed, they eat the
scales of other cichlids.
They attack their prey from behind and bite a
mouthful of scales off of their prey.
The scales are then stacked and crushed by a
second set of teeth and sent to the stomach
and intestine for protein digestion.
A scientist discovered that within a certain
species, Perissodus microlepis, there are two
One group has a mouth that is asymmetrically
curved to the left, while the other group has a
mouth that is asymmetrically curved to the
This allows the left mouthed fish to attack on
the the right, and the right mouth fish to attack
on the left.
Both of these fish are found to live in the same
Why is it helpful for them to live near each
Animal Classification and
Evolution not only explains why animals
appear and function as they do, but it also
explains family relationships within the animal
Groups of individuals are more closely related
if they share similar DNA. (You are more
closely related to your brothers/sisters than
your cousins, thus you should resemble your
brother/sister more so than your cousin.)
Genetic studies suggest that the oldest population of
African cichlids are found in Lakes Tanganyika and
These fish eventually invaded African rivers and Lakes
Victoria, Malawi and many other small lakes.
The invasion of Lake Victoria by Lake Kivu’s cichlids is
thought to have happened around 100,000 years ago.
This passage was closed around 40,000 years ago.
There are approximately 500 species of cichlid that are
found in Lake Victoria, yet not in Lake Kivu.
This represents one the most rapid origin of species
that is known to man.
Karl von Linne
Primarily remembered for collecting and
Designed the system that we use today
to classify animals.
Uses a two-part name to describe an
The first part indicates the genus, while the
second part indicates the species.
The genus name must be capitalized, while the
species name is lowercase.
The genus and species name are always listed
They must be written in italics or underlined.
Zoology: An Ecological
In the 1950’s the giant Nile perch was
introduced into Lake Victoria in an
attempt to increase the lake’s fishery.
This predator reduced the cichlid
population from 99% to less that 1% of
the total fish population and has led to
the extinction of many cichlid species.
The cichlids are algae eaters.
With nothing to eat the algae, it grew,
The decaying algae caused a depletion of
oxygen in the water.
Also, nile perch has to be dried, which has lead
to fisherman cutting down many of the trees in
the area to smoke the fish. This deforestation
has lead to further degradation of the water in
Lake Victoria due to runoff.
The reduction of water quality in turn led
to the death of more cichlid and caused
major problems to others.
The loss of Lake Victorian cichlids may
be the largest extinction event of
vertebrate species in modern human
Some Good News
Many cichlid species are recovering.
Nile perch population is down from 90%
in the early 80’s to somewhere around
World Resources and
There is a concern for the ecology of the
entire world, not just Africa’s lakes.
The problem lies mostly within
developing nations striving to keep up
with industrialized nations.
The focus of our ecological concerns are:
Exploitation of the world’s resources
Global overpopulation is at the root of virtually
all environmental problems.
92% of growth is in less developed countries.
That’s 5 billion of the world’s 6.3 billion people.
The rate of growth shows no signs of slowing
with some population estimates reaching 10.4
billion by the year 2100.
Human overpopulation is stressing world
Food production is maxed out.
Maximum oil consumption is depleting our
fossil fuel supplies and increasing the
greenhouse effect and global warming.
Deforestation of the world’s forests continues
due to a high demand for wood.
Tropical rainforests have been reduced
to 44% of their former size.
We are losing species that we do not
even know exist, and we are missing out
on resources that could lead to new
medicines, foods and textiles.
An endangered species is in imminent
danger of extinction throughout its range.
A threatened species is likely to become
endangered in the near future.
A 2003 U.S. Fish & Wildlife Service
Survey lists 1,263 species in the U.S.
and 1,824 foreign species as being either
endangered or threatened.
A global system of national parks to protect
large tracts of land and wildlife corridors that
allow movement between natural areas.
Protected landscapes and multiple-use areas
that allow controlled private activity but also
retain value as a wildlife habitat.
Zoos and botanical gardens to save species
whose extinction is imminent.