Taxonomy and Systematics

Review common characteristics of vertebrates.

Cladograms—shows evolutionary linkages

How do we organize vertebrates?

The Binomial System

• Carl Linnaeus created the binomial nomenclature system

• We use Latin because it’s a dead language that doesn’t change/add new words

• Specific epithet means the species name

Classification Schemes

• What criteria would you use to classify different creatures?

  • Morphological characteristics like eyes, ears, digits, teeth, etc

• But it’s not the only thing we use.

  

• What are we missing with morphology?

  

• Morphology or molecules?

  • DNA, RNA, and proteins can give us a clue into where the line is that divides species

Which of the 4 creatures below are most closely related?

• Use different criteria, and you will get different groups. What’s right? DNA has opened things up. Lots of changes are taking place.

• Cetacea and Artiodactyla (two-toed, mostly ruminants)

• DNA analysis revealed that whales evolved from within Artiodactyla and are more closely related to ruminants like cows than ruminants are to pigs

• Hippos are closest to whales, and ruminants are more closely related to the hippo/whale group than they are to pigs. Hippos and pigs not as closely related as once thought.

• The more we learn from DNA, the more will change – especially on lower classification levels.

Systematics

• Systematics: the study of the diversification of life forms—evolutionary interrelationships of living things

  • Geographic variation

  • Vertebrate distribution

  • Principles of evolution

  • Geologic record and evolution of vertebrates

Principles of evolution

• Lamarck thought that heritability of acquired characteristics were passed onto kids—like if you work out and get muscular, your kids will be muscular

• Darwin/Wallace—Natural selection

• Genetic Drift—small population, so minimal variation in traits

• Bottleneck—big population shrunk down by sudden event

• Founder Effect—some of population goes to different location, shrinking the gene pool

• Non-random breeding—selective breeding

• Mutation—when DNA randomly changes, causing variation in the gene pool

Evidence of Evolution

• Embryology

• Fossil evidence

• Homologous structures

• Molecular evidence

Textbook Tables

• Only 8 lobe-finned fishes compared to 30,000+ ray-finned fishes

• Lots of fish

• Total: 66,828 species in the major groups of living craniates

• Many more frogs than turtles (7000 versus 350)

Different ways to move

• Graviportal: slow run, can’t climb

• Arboreal: move along trees

• Ambulatory: walking

• Aerial: flying

• Volant: gliding

• Scansorial: climbing

• Cursorial: quick moving

• Aquatic: in the water

• saltatorial: jumping

• fossorial: digging