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General Biology: OrganismL Biology and Evolution - Set 1 > Vertebrates evolution > Flashcards

Vertebrates evolution Flashcards

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1
Q

What are the roots of the Chordata phylum?

A

530 MYA
- Chordate-like fossils in Canada & China are ancestral “missing links” between invertebrates & vertebrates
- Similar to lancelets but appeared to have a
larger brain and eyes, no cranium
- Present but rare in Burgess Shale
- Segmented body & tentacles 1.5 inches long

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2
Q

What are the four main features of chordates anatomy?

A
  • Notochord
  • Dorsal, hollow nerve cord
  • Pharyngeal slits
  • Muscular, post-anal tail
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3
Q

What is a notochord?

A

The notochord is a longitudinal, flexible rod between the digestive tube and nerve cord
- It provides skeletal support throughout most of
the length of a chordate
- In most vertebrates, a more complex, joined
skeleton develops, and the adult retains only
remnants of the embryonic notochord

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4
Q

What are dorsal hollow nerve cords?

A

The nerve cord of a chordate embryo develops from a plate of ectoderm that rolls into a tube dorsal to the notochord
- The nerve cord develops into the central
nervous system: the brain and the spinal cord

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5
Q

What is the muscular post-anal tail?

A

In many species, the tail is greatly reduced during embryonic development
- Chordates have a tail posterior to the anus
- The tail contains skeletal elements and muscle
blocks
- It provides propelling force in many aquatic
species

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6
Q

What are the pharyngeal clefts/slits?

A

In most chordates, grooves in the pharynx called pharyngeal clefts develop into slits that open to the outside of the body
- Functions of the pharyngeal slits:
- Suspension-feeding structures in many
invertebrate chordates
- Gas exchange in aquatic vertebrates
- Tetrapods have pharyngeal pouches that develop into parts of the ear, head, and neck (eustachian tube, middle ear, tonsils, parathyroid, and thymus)

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7
Q

What do Hox genes control?

A

They control morphology

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8
Q

How did Lewis discover hox genes?

A
  • Found a cluster of homeotic (Hox) genes in the
    chromosome
  • Saw colinearity in time and space
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9
Q

What did the gene order in the cluster Lewis found mimic?

A

The order of expression of genes and their function along the anterior-posterior (A-P) body axis

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10
Q

What does exhibiting temporal colinearity look like?

A

Having the anterior genes expressed first during development and posterior later

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11
Q

What are Hox genes?

A

Transcription factors
- Proteins that bind to specific sequences of DNA
(the Cis-regulatory elements) to control the
transcription of genetic information from DNA to
RNA

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12
Q

How do HOX genes orchestrate the construction of body parts?

A
  • DNA is wound up like a spool of yarn. As the
    spool is unwound the emerging genes become
    active
  • A new gene comes out of the spool every ninety
    minutes, which corresponds to the time needed
    for a new layer of the embryo to be built
  • It takes two days for the strand to completely
    unwind, the same time that’s needed for all the
    layers of the embryo to be completed
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13
Q

What organisms make up the subphylum Urochordata?

A

Also known as Tunicata, tunicates or sea squirts
- Two siphons
- Filter-feeding

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14
Q

What are tunicates?

A

Adult animals without backbones, a Chordate-like larva

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15
Q

What does appearance of self-recognization affect?

A

Whether tissue transplants graft or are rejected
- Fusion/rejection based on sharing same allele
for FuHC gene (Fusion Histocompatibility
Complex)

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16
Q

What makes the vertebrates phylum special?

A
  • A skeletal system and complex nervous system
    that allows vertebrates efficiency at two essential
    tasks
    • Capturing food
    • Evading predators
  • Vertebrae enclosed the spinal chord and
    replaced notochord
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17
Q

How many sets of Hox genes do vertebrates have?

A

2 sets

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18
Q

What do vertebrates possess that is involved in the formation of the cranium?

A

A neural crest

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19
Q

What is the neural crest and what does it form?

A
  • The neural crest is a group of embryonic cells
    that form near the dorsal margins of the closing
    neural tube
  • They form certain craniofacial structures
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20
Q

What are craniates?

A

Chordates that have a head
- A distinct skull contains a brain at the anterior
end of the dorsal nerve cord, eyes and other
sensory organs
- Enables chordates to coordinate more complex
movement and feeding behaviors

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21
Q

What are the main differences between chordates and craniates?

A

Chordates
- One hox gene cluster
- Less active
- No muscles lining the digestive tract
- Tubular heart
- No kidneys

Craniates
- Two hox gene clusters
- More active + higher metabolic rate
- Muscular lining of digestive tract
- 2-chambered heart
- Kidneys
- Hemoglobin & Red blood cells

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22
Q

What organism belongs to the myxini family?

A

Hagfish (~30 species)
- Marine scavengers
- Cartilaginous skeleton & notochord
- No jaws and very reduced vertebrae
- Fossil evidence date them at ~300 MYA
- Glands along body produce copious amounts of
slime

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23
Q

What organism belongs to the Petromyzontida family?

A

Lampreys
- Represent the oldest living lineage of vertebrates
- Cartilaginous skeleton
- The notochord has cartilaginous projections that
enclose the nerve cord
- Jawless mouth
- External parasites

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24
Q

What are conodonts?

A

Extinct jawless vertebrates with mineralized elements

25
Q

What are ostracoderms?

A

Extinct jawless vertebrate with mineralized teeth and armor from ~450-375 MYA
- Used muscular pharynx to suck in food

26
Q

What hypothesis about mineralization was formed after the discovery of the ostracoderms?

A

Mineralization was initiated in teeth, then spread to armor, and later still to the endoskeleton

27
Q

What are gnathostomes?

A

Vertebrates that have jaws and paired fins

28
Q

What is the advantage of having jaws & paired fins?

A

Jaws & paired fins enabled many fish species to be active predators, allowing for diversification of lifestyles & nutrient sources

29
Q

What is the current hypothesis about how vertebrates jaws evolved?

A

Vertebrate jaws evolved by modification of skeletal rods that previously supported anterior pharyngeal slits
- Remaining gill slits remain as sites of respiration

30
Q

What characteristic are common to gnathostomes?

A
  • Genome duplication, including duplication of
    Hox genes
  • An enlarged forebrain associated with enhanced
    senses of smell and vision
  • The lateral line system, rows of organs sensitive
    to vibrations that are located along each side of
    the body of aquatic gnathostomes
31
Q

What did the Silurian and early Devonian periods see a dramatic increase in?

A

Jawed fish in the fossil record

32
Q

What kind of skeletal structure do cartilaginous fish have?

A

They have a flexible endoskeleton of cartilage rather than bone

33
Q

What is the cartilaginous skeleton?

A

A derived condition

34
Q

What is the evolution of the cartilaginous skeleton in chondrichthyes?

A
  • Primitive gnathostomes that pre-date the
    Chondrichthyes had bony skeletons and teeth,
    ie. contained mineral mineral calcium phosphate
  • Bonelike tissues are found in some early shark
    fossils
  • Traces of bone found in scales, based of teeth,
    and on vertebrae surface
  • Loss of bone is modern Chondrichthyes
    emerged after they diverged from gnathostomes
35
Q

What are osteichthyes (bony fish)

A
  • The most numerous vertebrates, both in
    individuals & species (~30,000)
  • Bony endoskeleton containing calcium
    phosphate
  • Scales also derived from bone
36
Q

What are the three extant classes?

A
  • Actinopterygii: ray-finned fishes
  • Actinistia: lobe-finned fishes (coelocanths)
  • Dipnoi: lungfish
37
Q

What kind of organisms belongs to the Actinopterygii class?

A

The ray-finned fishes - named for the bony rays that support fins
- Includes bass, trout, perch, tuna and herring
- Fins may be modified for maneuvering, defense,
and other functions

38
Q

What kind of organisms belongs to the Actinistia class?

A

Lobe-finned fishes with muscular pectoral & pelvic fins supported by extensions of bony skeleton

39
Q

What did Marjorie Courtenay-Latimer do?

A
  • Rediscovered Coelacanths, which were thought
    to have gone extinct 65 mya, in 1938
  • Genus Latimeria is named for her
  • Now present in S. Africa and S. Pacific
40
Q

What organism belongs to the dipnoi class?

A

Lungfish
- Generally inhabit stagnant ponds & swamps
- Can gulp air into lungs connected to the pharynx
- Australian lungfish still have gills
- During dry season, some lungfishes can burrow
into mud & aestivate

41
Q

Where would we find transitional species?

A
  • Shallow estuary or tidal flat
  • Warm, equatorial climate
  • Late Devonian era, around 370 mya
  • Presently exposed for exploration
42
Q

What did Ted Daeschler & Neil Shubin discover in 2006?

A

10 specimens of Tiktaalik found in a Canadian rock bed estimated to be 375 million years old

43
Q

What fish like characteristics did the Tiktaalik specimens have?

A
  • Gills and a lung, gills had a reduced bony covering
  • Had scales covering its body like a fish
  • Had fins that could be used for swimming
44
Q

What tetrapod characteristics did the Tiktaalik specimens have?

A

-Had a flat skull
- Had eyes on top of its skull
- Had ear notches that were larger than those
seen in other Devonian fish (notches later
became ears)
- Had a full set of ribs that were needed for
breathing and support out of water
- Had a neck that could move its head around

45
Q

What was known about the fin skeleton that Tiktaalik specimen had?

A
  • It is a transition between a fin and foot
  • Probably wasn’t used for walking but could
    support animal’s weight
  • Fossil record shows fins increasingly evolved an
    internal structure similar to limbed animals
46
Q

What did Neil Subin dub the Tiktaalik and why?

A

He dubbed it a “FIshapod” because it possessed multiple intermediate characteristics of fish and tetrapods

47
Q

Why was the date of the first tetrapod revised to 395 mya?

A
  • Tracks were found on what would have been the
    Polish coast
  • Spacing indicates animals from 0.5 to 2.5 cm
    long
  • No fossil skeleton found yet
48
Q

What are the five main characteristics of tetrapods?

A
  • Four “feet”
  • Digits - feet have digits to transmit muscle force
    to ground
  • Neck - head is separated from body by 1 or
    more vertebrae
  • Pelvic girdle - bones fused to vertebrae so that
    force from hind legs on ground is transferred to
    rest of body
  • Pharyngeal clefts - give rise to facial structures
    and glands, loss of gills
49
Q

What did amphibians benefit from as the earliest terrestrial tetrapods?

A

They benefited from moist climate, abundant food & relatively little competition

50
Q

What amphibians live two lives?

A

Aquatic tadpole larva metamorphoses to a terrestrial adult frog
- Tadpoles usually aquatic herbivores with gills, a
lateral line system, and swim by undulating tail
- During metamorphosis, the tadpole develops
legs, the lateral line disappears, and gills are
replaced by lungs
- Adult frogs are carnivorous hunters

51
Q

What amphibians live one life?

A
  • Amphibians such as salamandres do not live 2
    lives - larvae and adults look alike
  • Aquatic salamander species often show
    paedomorphosis - retention of larval features in
    a sexually mature adult
52
Q

Where are amphibians generally found?

A
  • Generally found near water or in very humid
    environments
  • Many species rely on moist skin for gas
    exchange
  • Eggs lack shell & dehydrate quickly in dry air
53
Q

What kind of egg enables all-terrestrial life cycles?

A

An amniotic egg
- Extraembryonic membranes function in gas
exchange, waste storage, and transfer of stored
nutrients to embryo

54
Q

What reptilian adaptations for terrestrial life are not generally found in amphibians?

A
  • Reptiles obtain oxygen with lungs (increasing use
    of ribcage), not through their skin
  • Scales, containing keratin, waterproof skin,
    preventing dehydration
  • Internal fertilization, has to occur before shell is secreted
55
Q

What is an ectotherm?

A
  • Organisms that regulate their body temperature
    through behavior adaptations like basking or
    panting
  • Most reptiles are ectothermic, absorbing
    external heat as the main source of body heat
56
Q

What did scientists discover about dinosaurs when they were able to measure their body temperature?

A

That some dinosaurs were as warm as most modern mammals
- They did this by measuring the concentrations of
isotopes carbon-13 and oxygen-18 in bioapatite,
a mineral found in teeth and bone

57
Q

What did the sequences of T. rex collagen proteins indicate?

A

That the closest living relative to them is an ostrich

58
Q

What are archaeopteryx?

A

Mesozoic birds known from Bavarian fossils, fist found in 1860
- Lived ~150 MYA, during late Jurassic
- Had clawed forelimbs, teeth, and a long tail
containing vertebrae
- Probably glided or flew short distances

59
Q

What were extinct by the end of the Cretaceous period?

A

Dinosaurs went extinct
- Dinosaurs may have been in decline before the
asteroid impact near Yucatan Peninsula

General Biology: OrganismL Biology and Evolution - Set 1 (23 decks)

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