Final Exam - Vertebrates and Early Jawless Fish

Question 1

Vertebrate group

Answer 1

Phylum Chordata -> subphylum vertebrata

Question 2

IUCN

Answer 2

International Union for Conservation of Nature:
- Governments + civil society organisations, united under the common goal of protecting nature and conserving life on earth
- World’s most comprehensive inventory of the global conservation status of biological species
- Conservation (biology)
- Protecting Earth’s biodiversity
- species, habitats, and ecosystems
- “Red List” keeps track of endangerment status of species

Question 3

Biodiversity

Answer 3

R.F. Dasmann in 1968
Variety of different life forms on Earth, and the variations in the species
- Total genes, species, and ecosystems of a region
- Taxonomic: number of species
Ecological: number of ecosystems
Morphological: genetic diversity
Important for Conservation

Question 4

Mass Extinctions

Answer 4

High rate of extinctions
1. Ordovician (440 mya): 86% of species
2. Devonian (364 mya): 75%
3. Permian (250 mya): 96%
4. Triassic (200 mya): 50-75%
5. Cretaceous (65 mya): 75%
6. Holocene (now): ?%
- Anthropocene sixth mass extinction?
- 83% wild mammals, 80% marine mammals, 15% fish have vanished

Question 5

Human-Induced Threats and Extinctions

Answer 5

50 000 years of vertebrate extinctions
- Many large vertebrates in Australia (Pleistocene Megafauna)
- Ex: Moa bird (1400), The Dodo (mid 1600s), Tasmanian Tiger (1936)
- World pops of vertebrates fell overall by 60% between 1970-2014

Question 6

How Can we Successfully Conserve Vertebrates?

Answer 6

“the avoidance of extinction”, is it enough?
Reactive vs. Proactive
Successful species conservation:
- Maintaining multiple populations across ecological settings
- With replicated populations in each setting
- Populations should be self-sustaining, healthy and genetically robust
- Resilient to climate and other environmental changes

Question 7

Subphylum Vertebrata (Craniata)

Answer 7

• Neural crest = “quadroblastic” -> anteriorly lead to tri-partite brain (forebrain, midbrain, hindbrain)
  
  • forebrain houses the cerebral cortex, the main processing centre of the brain!
• Mineralized tissue
  - Cranium (AKA skull) and vertebrae (surround and protect nerve cord)
• Pair of semi-circular canals
• Ectodermal placodes (epidermis thickening -> sensory systems)
• Homeobox (Hox) genes double duplication (head-tail plan)

Question 8

How did Vertebrates get so Big/Fast/Smart?

Answer 8

Musculoskeletal mods
- Endoskeleton
- Permits almost unlimited body size with much greater economy of building materials
- Forms excellent jointed scaffolding for attachment of segmented muscles
- Physiology
- Mods of digestive, respiratory, circulatory, and excretory systems to meet increased metabolic demand

Question 9

Tripartite Brain

Answer 9

• Forebrain: olfactory system
• Midbrain: ocular system
• Hindbrain: balance, hearing, taste, touch, respiration, circulation

Question 10

Early vertabrates

Answer 10

Chengjiang Fauna, China
1. Myllokunmingia (518 mya)
Earliest vertebrate?
Single specimen
Vertebrate features:
- no vertebrae but a cranium and segments out for notochord
- like a hagfish?
2. Haikouichthys (518 mya)
Vertebrate features:
- cartilaginous gill supports
- Like a lamprey?

Question 11

Early Jawless Fishes -> “Ostracoderms”

Answer 11

• Bony armour: dermal plates
• Pteraspids (Heterostracans)
  
  • Paired nasal openings and three-layer dermal skeleton
• Myopterygians (Osteostracans; Anaspids; Cephalaspids)
  
  • Paired lateral fin fish; dorsal and/or anal fins