ZoologyZoology

An Evolutionary and Ecological An Evolutionary and Ecological PerspectivePerspective

Main ConceptsMain Concepts

The field of Zoology is the study of The field of Zoology is the study of animals.animals. It is a very broad field with many It is a very broad field with many

subdisciplines.subdisciplines.

Main ConceptsMain Concepts

An understanding of evolutionary An understanding of evolutionary processes is very important in zoology processes is very important in zoology because evolution explains the family because evolution explains the family relationships among animals and how the relationships among animals and how the great variety of animals arose.great variety of animals arose.

Main ConceptsMain Concepts

An understanding of ecological principles An understanding of ecological principles is very important in zoology because it is very important in zoology because it helps zoologists to understand the helps zoologists to understand the interrelationships among individual animals interrelationships among individual animals and groups of animals. Understanding and groups of animals. Understanding ecological principles also helps zoologists ecological principles also helps zoologists to understand how human interference to understand how human interference threatens animal populations and the threatens animal populations and the human environment.human environment.

Zoology basicsZoology basics

Plainly stated, Zoology is the study of Plainly stated, Zoology is the study of animals.animals.

One of the broadest fields in science due One of the broadest fields in science due to the immense variety of animals.to the immense variety of animals. Ex. 20,000 species of described bony fishEx. 20,000 species of described bony fish Ex. 300,000 species of described beetlesEx. 300,000 species of described beetles

SpecializationSpecialization

Most zoologists specialize in one or more Most zoologists specialize in one or more subdisciplines.subdisciplines.

They may study particular functional, They may study particular functional, structural, or ecological aspects of one or structural, or ecological aspects of one or more animal groups or they may choose more animal groups or they may choose to specialize in a particular group of to specialize in a particular group of animals.animals.

Table 1.1Table 1.1Examples of Specializations in Zoology

Subdiscipline Description

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

Table 1.2Table 1.2

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 Zoology: An Evolutionary PerspectivePerspective

Organic evolution is change in the genetic Organic evolution is change in the genetic makeup of populations of organisms over time.makeup of populations of organisms over time.

It is the source of animal diversity, and it It is the source of animal diversity, and it explains family relationships within family explains family relationships within family groups.groups.

Charles Darwin published convincing evidence Charles Darwin published convincing evidence of evolution in 1859 and proposed a of evolution in 1859 and proposed a mechanism that could explain evolutionary mechanism that could explain evolutionary change. Since that time, many scientists have change. Since that time, many scientists have become convinced that evolution occurs.become convinced that evolution occurs.

Structure and Function Structure and Function VariationVariation

Understanding how the diversity of Understanding how the diversity of animal structure and function arose is animal structure and function arose is one of the many challenges faced by one of the many challenges faced by zoologists.zoologists.

For example, lets take a look at the For example, lets take a look at the cichlid scale eaters of Africa.cichlid scale eaters of Africa.

As you may have guessed, they eat the As you may have guessed, they eat the scales of other cichlids.scales of other cichlids.

CichlidsCichlids

They attack their prey from behind and bite a They attack their prey from behind and bite a mouthful of scales off of their prey.mouthful of scales off of their prey.

The scales are then stacked and crushed by a The scales are then stacked and crushed by a second set of teeth and sent to the stomach second set of teeth and sent to the stomach and intestine for protein digestion.and intestine for protein digestion.

A scientist discovered that within a certain A scientist discovered that within a certain species, species, Perissodus microlepisPerissodus microlepis, there are two , there are two subgroups. subgroups.

CichlidsCichlids

One group has a mouth that is asymmetrically One group has a mouth that is asymmetrically curved to the left, while the other group has a curved to the left, while the other group has a mouth that is asymmetrically curved to the mouth that is asymmetrically curved to the right.right.

This allows the left mouthed fish to attack on This allows the left mouthed fish to attack on the the right, and the right mouth fish to attack the the right, and the right mouth fish to attack on the left.on the left.

Both of these fish are found to live in the same Both of these fish are found to live in the same habitat.habitat.

Why is it helpful for them to live near each Why is it helpful for them to live near each other?other?

Animal Classification and Animal Classification and Evolutionary Evolutionary RelationshipsRelationships

Evolution not only explains why animals appear Evolution not only explains why animals appear and function as they do, but it also explains and function as they do, but it also explains family relationships within the animal kingdom.family relationships within the animal kingdom.

Groups of individuals are more closely related Groups of individuals are more closely related if they share similar DNA. (You are more if they share similar DNA. (You are more closely related to your brothers/sisters than closely related to your brothers/sisters than your cousins, thus you should resemble your your cousins, thus you should resemble your brother/sister more so than your cousin.)brother/sister more so than your cousin.)

CichlidsCichlids

Genetic studies suggest that the oldest population of Genetic studies suggest that the oldest population of African cichlids are found in Lakes Tanganyika and African cichlids are found in Lakes Tanganyika and Kivu.Kivu.

These fish eventually invaded African rivers and Lakes These fish eventually invaded African rivers and Lakes Victoria, Malawi and many other small lakes.Victoria, Malawi and many other small lakes.

The invasion of Lake Victoria by Lake Kivu’s cichlids is The invasion of Lake Victoria by Lake Kivu’s cichlids is thought to have happened around 100,000 years ago. thought to have happened around 100,000 years ago.

This passage was closed around 40,000 years ago. This passage was closed around 40,000 years ago. There are approximately 500 species of cichlid that are There are approximately 500 species of cichlid that are

found in Lake Victoria, yet not in Lake Kivu.found in Lake Victoria, yet not in Lake Kivu. This represents one the most rapid origin of species This represents one the most rapid origin of species

that is known to man.that is known to man.

Karl von Linne Karl von Linne aka Linnaeusaka Linnaeus

1707-17781707-1778 Primarily remembered for collecting and Primarily remembered for collecting and

classifying plants.classifying plants. Designed the system that we use today Designed the system that we use today

to classify animals. to classify animals.

Binomial nomenclatureBinomial nomenclature

Uses a two-part name to describe an organism.Uses a two-part name to describe an organism. The first part indicates the genus, while the The first part indicates the genus, while the

second part indicates the species.second part indicates the species. The genus name must be capitalized, while the The genus name must be capitalized, while the

species name is lowercase. species name is lowercase. The genus and species name are always listed The genus and species name are always listed

together.together. They must be written in italics or underlined.They must be written in italics or underlined.

DKPCOFGSDKPCOFGS

DomainDomain KingdomKingdom PhylumPhylum Class Class OrderOrder FamilyFamily GenusGenus SpeciesSpecies

Zoology: An Ecological Zoology: An Ecological perspectiveperspective

In the 1950’s the giant Nile perch was In the 1950’s the giant Nile perch was introduced into Lake Victoria in an introduced into Lake Victoria in an attempt to increase the lake’s fishery.attempt to increase the lake’s fishery.

This predator reduced the cichlid This predator reduced the cichlid population from 99% to less that 1% of population from 99% to less that 1% of the total fish population and has led to the total fish population and has led to the extinction of many cichlid species.the extinction of many cichlid species.

Lake VictoriaLake Victoria

The cichlids are algae eaters.The cichlids are algae eaters. With nothing to eat the algae, it grew, With nothing to eat the algae, it grew,

unchecked.unchecked. The decaying algae caused a depletion of The decaying algae caused a depletion of

oxygen in the water. oxygen in the water. Also, nile perch has to be dried, which has lead Also, nile perch has to be dried, which has lead

to fisherman cutting down many of the trees in to fisherman cutting down many of the trees in the area to smoke the fish. This deforestation the area to smoke the fish. This deforestation has lead to further degradation of the water in has lead to further degradation of the water in Lake Victoria due to runoff.Lake Victoria due to runoff.

Lake VictoriaLake Victoria

The reduction of water quality in turn led The reduction of water quality in turn led to the death of more cichlid and caused to the death of more cichlid and caused major problems to others.major problems to others.

The loss of Lake Victorian cichlids may The loss of Lake Victorian cichlids may be the largest extinction event of be the largest extinction event of vertebrate species in modern human vertebrate species in modern human history.history.

Some Good NewsSome Good News

Many cichlid species are recovering.Many cichlid species are recovering. Nile perch population is down from 90% Nile perch population is down from 90%

in the early 80’s to somewhere around in the early 80’s to somewhere around 50% now.50% now.

World Resources and World Resources and Endangered AnimalsEndangered Animals

There is a concern for the ecology of the There is a concern for the ecology of the entire world, not just Africa’s lakes.entire world, not just Africa’s lakes.

The problem lies mostly within The problem lies mostly within developing nations striving to keep up developing nations striving to keep up with industrialized nations.with industrialized nations.

The focus of our ecological concerns are:The focus of our ecological concerns are: Global overpopulationGlobal overpopulation Exploitation of the world’s resourcesExploitation of the world’s resources

PopulationPopulation

Global overpopulation is at the root of virtually Global overpopulation is at the root of virtually all environmental problems.all environmental problems.

92% of growth is in less developed countries.92% of growth is in less developed countries. That’s 5 billion of the world’s 6.3 billion people.That’s 5 billion of the world’s 6.3 billion people. The rate of growth shows no signs of slowing The rate of growth shows no signs of slowing

with some population estimates reaching 10.4 with some population estimates reaching 10.4 billion by the year 2100.billion by the year 2100.

World ResourcesWorld Resources

Human overpopulation is stressing world Human overpopulation is stressing world resources.resources.

Food production is maxed out.Food production is maxed out. Maximum oil consumption is depleting our Maximum oil consumption is depleting our

fossil fuel supplies and increasing the fossil fuel supplies and increasing the greenhouse effect and global warming.greenhouse effect and global warming.

Deforestation of the world’s forests continues Deforestation of the world’s forests continues due to a high demand for wood.due to a high demand for wood.

Wildlife AlertWildlife Alert

Tropical rainforests have been reduced Tropical rainforests have been reduced to 44% of their former size.to 44% of their former size.

We are losing species that we do not We are losing species that we do not even know exist, and we are missing out even know exist, and we are missing out on resources that could lead to new on resources that could lead to new medicines, foods and textiles.medicines, foods and textiles.

Endangered vs. Endangered vs. ThreatenedThreatened

An endangered species is in imminent An endangered species is in imminent danger of extinction throughout its range.danger of extinction throughout its range.

A threatened species is likely to become A threatened species is likely to become endangered in the near future.endangered in the near future.

A 2003 U.S. Fish & Wildlife Service A 2003 U.S. Fish & Wildlife Service Survey lists 1,263 species in the U.S. Survey lists 1,263 species in the U.S. and 1,824 foreign species as being either and 1,824 foreign species as being either endangered or threatened.endangered or threatened.

Preservation of Preservation of endangered species endangered species

A global system of national parks to protect A global system of national parks to protect large tracts of land and wildlife corridors that large tracts of land and wildlife corridors that allow movement between natural areas.allow movement between natural areas.

Protected landscapes and multiple-use areas Protected landscapes and multiple-use areas that allow controlled private activity but also that allow controlled private activity but also retain value as a wildlife habitat.retain value as a wildlife habitat.

Zoos and botanical gardens to save species Zoos and botanical gardens to save species whose extinction is imminent.whose extinction is imminent.