ZOOLOGY - CHAPTER 1: An Evolutionary and Ecological Perspective

BSPSY 2ND YEAR (REVIEWER)

Zoology

Is the scientific study of animals and their behavior, physiology, classification, and distribution.

Entomology

Is the branch of zoology that focuses on the study of insects.

Herpetology

Is the branch of zoology that studies reptiles and amphibians.

Ichthyology

Is the branch of zoology that focuses on the study of fish.

Mammalogy

Is the branch of zoology that studies mammals.

Ornithology

Is the branch of zoology that focuses on the study of birds.

Protozoology

Is a branch of zoology that studies about protozoa.

Cichlid fishes

Mouth Brooding in ____.

• Female carries eggs inside her mouth.

• Fertilization occurs after sperm enters the female's mouth.

• Eggs develop inside the mouth.

• Young return to the mother's mouth when threatened.

IMPORTANT:

• Protects eggs and young from predators.

• Increases offspring survival.

Cichlid fishes

• 2,000-3,000 known species.

• Demonstrate remarkable animal diversity.

• Used throughout the chapter to explain evolution and ecology.

• Highly diverse in:
  - Color patterns
  - Body forms
  - Habitats
  - Feeding habits

Evolutionary Perspective

• Shapes the diversity of animals.

• Understanding this helps explain what animals are and how they originated.

Charles Darwin

• Published convincing evidence for evolution in 1859.

• Proposed a mechanism to explain evolutionary change.

• His proposal serves as the foundation of modern zoology.

Organic evolution

• Is the change in the genetic makeup of populations over time.

• It is the source of animal diversity.

Evolution of Color Patterns

• Different populations became geographically isolated.

• Isolation occurred among rocky habitats separated by sandy areas.

• Fish rarely crossed sandy regions because of predators.

• Breeding mainly occurred within isolated populations.

• Over time, different _______ evolved.

Evolution of African Cichlids

• Oldest cichlid populations found in:
  - Lake Tanganyika
  - Lake Kivu

• They later spread to:
  - Lake Victoria
  - Lake Malawi
  - Other African lakes

• Geographic isolation promoted formation of new species.

Evolutionary Plasticity

• Lake Victoria nearly dried out about 14,700 years ago.

• Some cichlid populations survived in isolated refuges.

• After the lake refilled, these populations recolonized the lake.

• More than 500 cichlid species evolved in fewer than 15,000 years.

• This rapid diversification is called ________?

Phylogenetic Tree

• Zoologists study how different animal groups are related.

• Evolutionary relationships are represented using tree diagrams.

Binomial Nomenclature

• Developed by Carl von Linné (Linnaeus)

• Every species has a two-part scientific name:
  - Genus name
  - Species name
  Ex. Staphylococcus aureus

Rules for Binomial Nomenclature

• Do not use the species epithet alone.

• The genus name or its abbreviation should always accompany it.

Taxonomic Hierarchy

Ecology

• Greek words: oikos, meaning house + logos, to study)

• It is the study of the relationships between organisms and their environment.

Case Study: Lake Victoria

Introduction of the Nile Perch

• In the 1950s, the Nile perch (Lates niloticus) was introduced into Lake Victoria.

• Purpose: To increase the lake's fishery production.

• Result: Unexpected ecological consequences.

Case Study: Lake Victoria

Ecological Effects of the Nile Perch:

• Cichlid fish biomass decreased from 80% to less than 1%.

• About 65% of cichlid species became extinct.

• The loss of cichlids disrupted the lake ecosystem.

Chain of Ecological Consequences:

Introduction of Nile Perch → Decline of cichlid fishes → Algae increased → Dead algae decomposed → Oxygen levels decreased → Water quality deteriorated → More aquatic organisms were affected.

Case Study: Lake Victoria

Economic Consequences

Changes resulting from the Nile perch introduction:

• Nile perch became an important commercial fish.

• Large fishing fleets replaced many local fishermen.

• Fish processing shifted to large corporations.

• Increased agriculture contributed to:
  - Deforestation
  - Sewage pollution
  - Agricultural runoff
  - Industrial pollution

Case Study: Lake Victoria

Ecological Lessons
Positive developments:

• Heavy fishing reduced Nile perch populations.

• Some cichlid species began to recover.

• Certain species evolved adaptations to survive low oxygen levels.

Ex., increased gill surface area and changes in head morphology.