An Evolutionary and Ecological Perspective Zoology An Evolutionary and Ecological Perspective

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

Main Concepts 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.

Main Concepts 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.

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

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

Examples of Specializations in Zoology Table 1.1 Examples 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 1.2 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 Perspective 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 groups. 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 Variation Understanding how the diversity of animal structure and function arose is one of the many challenges faced by zoologists. 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.

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 subgroups.

Cichlids 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 right. 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 habitat. Why is it helpful for them to live near each other?

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

Cichlids Genetic studies suggest that the oldest population of African cichlids are found in Lakes Tanganyika and Kivu. 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 aka Linnaeus 1707-1778 Primarily remembered for collecting and classifying plants. Designed the system that we use today to classify animals.

Binomial nomenclature Uses a two-part name to describe an organism. 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 together. They must be written in italics or underlined.

DKPCOFGS Domain Kingdom Phylum Class Order Family Genus Species

Zoology: An Ecological perspective 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.

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

Lake Victoria 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 history.

Some Good News Many cichlid species are recovering. Nile perch population is down from 90% in the early 80’s to somewhere around 50% now.

World Resources and Endangered Animals 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: Global overpopulation Exploitation of the world’s resources

Population 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.

World Resources Human overpopulation is stressing world resources. 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.

Wildlife Alert 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.

Endangered vs. Threatened 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.

Preservation of endangered species 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.