Final Exam - Vertebrates and Early Jawless Fish Flashcards

1
Q

Vertebrate group

A

Phylum Chordata -> subphylum vertebrata

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2
Q

IUCN

A

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

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3
Q

Biodiversity

A

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

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4
Q

Mass Extinctions

A

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

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5
Q

Human-Induced Threats and Extinctions

A

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

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6
Q

How Can we Successfully Conserve Vertebrates?

A

“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

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7
Q

Subphylum Vertebrata (Craniata)

A
  • 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)
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8
Q

How did Vertebrates get so Big/Fast/Smart?

A

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

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9
Q

Tripartite Brain

A
  • Forebrain: olfactory system
  • Midbrain: ocular system
  • Hindbrain: balance, hearing, taste, touch, respiration, circulation
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10
Q

Early Vertebrates

A

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?

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11
Q

Early Jawless Fishes -> “Ostracoderms”

A
  • 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
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