Week 6 Flashcards
(76 cards)
1
Q
Definition: Taxonomy
A
The science of naming and classifying organisms within groups.
Groups are known as a ‘Taxa’ (plural) or ‘Taxon’ (single)
2
Q
Definition: Phylogeny
A
The evolutionary history of a species or group of species
(‘tree of life’)
3
Q
Definition: Systematics
A
The science of determining evolutionary relationships among organisms
4
Q
Give four criteria for classifying organisms?
A
- Morphological characters
- Fossil record
- Embryology
- Molecular analysis (genetic differences)
5
Q
Evolutionary relationships: Are homologous or analogous characters more important when determining phylogenic relationships?
A
Homologous are more important for classifying an organism.
6
Q
Evolutionary relationships: What can be used to find primitive characters in living organisms?
A
Fossil record
(however this may be poor, and convergent evolution obscures relationships, so Embryology and Vestigial organs provide useful clues)
7
Q
What is increasingly frequently used to determine evolutionary relationships?
A
Genetic similarity, which can be measured via molecular analyses
8
Q
True / False
How we classify organisms indicates a single similarity and difference between them
A
False: it indicated overall similarities and differences
9
Q
True / False
Classification of organisms reflect their evolutionary histories
A
True
10
Q
True / False
Classification uses a hierarchy of units, from phylum to order
A
False: The classification uses a hierarchy of units from kingdom to species.
11
Q
Phylogenic classification hierarchy order
A
Kingdom, Phylum, Class, Order, Family, Genus, Species
12
Q
True / False
Species are referred to by three-part scientific names, following loose rules.
A
False: Species are referred to by two-part scientific names, following strict rules.
(The binomial naming system.)
13
Q
True / False
When determining phylogenies, all characters are considered equally.
A
False: When determining phylogenies, some characters are more important than others.
(For example, only homologous characters reflect evolutionary relationships)
14
Q
Schools of thought in systematics: Phenetic system
A
- Groups organisms based on phenotypic similarity only
- Groups with the most traits in common are supposed to be more closely related
- Unreliable (Doesn’t distinguish between homologous and analogous)
- Now uncommon but sometimes best option/1st stage
15
Q
Schools of thought in systematics: Classic evolutionary
A
- All shared characters, primitive and derived.
- Accepts both mono- and paraphyletic groups
- Groups organisms based on similarity of characters that reflect evolutionary relationships
16
Q
Schools of thought in systematics: Cladistic systems
A
- Derived characters most important
- Accepts only monophyletic groups
- Groups organisms based on similarity of characters that reflect evolutionary relationships
17
Q
What are phylogenetic trees?
A
A graphical representation of evolutionary relationships among a set of organisms or groups of organisms
18
Q
What are simple phylogenetic trees?
A
- Order of organisms/orientation of the tree is arbitrary
- D has not evolved from A, both evolved from a common ancestor
- A-D may be equally ‘evolved’, A not more primitive
- Relationships are shown, but time only relative
19
Q
Types of phylogenetic tree?
A
Cladogram
Phylogram
Dendrogram (Ultrametric)
20
Q
Example of a monophyletic taxon
A
Class Mammalia
21
Q
Example of paraphyletic taxon
A
Class Reptilia
22
Q
Example of polyphyletic taxon
A
Green algae, brown algae, red algae
Algae sometimes considered polyphyletic, however, blue-green algae (cyanobacteria) are eubacteria
23
Q
Time to a phylogenetic tree: Radiometric dating
A
Compares amount of radioactive isotope with amount of decay products (decay rate known) to estimate age
24
Q
Time to a phylogenetic tree: Stratigraphy
A
Layering of deposited rocks allows geological timescale to be estimated
25
Time to a phylogenetic tree: Molecular clocks
Amount of genetic divergence used to estimate timing
26
What is the name of the classification system we use in modern day?
Linnaean system
(After Carl Linnaeus 1707-1778)
(An inclusive system of classifying of organisms - uses a hierarchy, he also formed the binomial nomenclature)
27
What does embryology of vertebrates show, when classifying organisms
Embryos of vertebrates show shared characteristics that reveal a common ancestor
28
What are the three different systems of thought in systematics?
Phenetic system
Classic evolutionary system (most commonly used today)
Cladistic system
29
What is monophyletic group?
Ancestor and all descendants
30
What is paraphyletic group
Ancestor and not all descendants
31
What is polyphyletic group?
Missing ancestors (less common)
32
Classic evolutionary vs Cladistic systems
Both group organisms on similarity of characters reflecting evolutionary relationships.
Classic: accepts mono- and paraphyletic groups. All shared characters, priimitive and derived
Cladistic: only accepts monophyletic groups. Derived characters most important
33
What are the 6 kingdoms on 'the tree of life'?
- Eubacteria
- Archaea
- Protista
- Plantae
- Fungi
- Animalia
(Some believe in 3 main domains instead: Bacteria, Archaea, Eukarya)
34
Features of the Eubacteria kingdom?
unicellular, prokaryotic
peptidoglycan in the cell wall
e.g.:
cyanobacteria
soil bacteria
pathogenic bacteria
35
Features of the Archaea kingdom?
unicellular, prokaryotic
lacking peptidoglycan in the cell wall
e.g.:
halophile bacteria
thermophile bacteria
metanogen bacteria
36
Features of the Protista kingdom?
uni- or multicellular, eukaryotic
heterotrophic/photosynthetic
e.g.:
Paramecium
algae
37
Features of the Fungi kingdom?
multicellular
heterotrophic
not mobile
e.g.:
mushrooms
yeasts
38
Features of the Plantae kingdom?
multicellular
photosynthetic
not mobile
e.g.:
ferns, mosses
trees
39
Features of the Animalia kingdom?
multicellular
heterotrophic
mobile
e.g.
corals, insects
mammals
(Ancestor 800-675 mya cf. Choanoflagellates)
40
What are the key characteristics of Animalia?
- Eukaryotic, multicellular, no cell walls
- Heterotrophic (Ingest and Digest)
- Mobile
- Cell differentiation (four main tissue types)
- Sexual reproduction (usually)
- Blastula stage of development (unique)
41
How can we classify animals by Body symmetry? (body plans)
Represents evolutionary steps on the animals tree of life. Body symmetry includes:
- Asymmetric,
- Radial
- Bilateral
42
How can we classify animals by Body cavities? (body plans)
Body cavities include:
- Coelomates (Coelom and internal organs surrounded by mesoderm)
- Acoelomates
(Do not have enclosed cavities)
- Pseudocoelomates
(Lines with mesoderm, but no mesoderm surrounds the internal organs)
43
Difference in development of Animalia?
- Protostomes (Mollusks, annelids, arthropods)
Two layers of cells are offset
Solid masses of mesoderm tissue split and form coelom
Mouth develops from blastopore
44
Difference in development of Animalia?
Deuterostomes
(echioderms, chordates)
Two layers of cells are aligned
Outward bulges of developing digestive tract form coelom
Anus develops from blastopore
45
Characteristics of Phylum Porifera?
(Meaning: “Pore bearing”. Eg sponge)
- c. 5,500 spp.
- Aquatic (mostly marine)
- Sessile, but with free-swimming larvae
- Asymmetric (some radial symmetry)
- No true tissues/organs
- Flagellated collar cells
- Mostly hermaphrodite
46
Characteristics of Phylum Cnidaria
(Meaning: “Stinging” (Cnida = nettle) Eg Jellyfish)
- c. 10,000 spp.
- Include jellyfish, sea anemones and corals
- Aquatic (mostly marine)
- Radial symmetry
- Two body forms: sessile polyps & mobile medusae
- Acoelomates, two cell layers: epidermis & gastrodermis
47
Examples of Phylum Cnidaria
Chironex fleckeri (box jellyfish or ‘sea wasp’) The sting from this Australian & SE Asian jellyfish can be fatal as they can produce a heart attack
Aurelia aurita (moon jellyfish) The sting from this species is usualy harmless, you may not feel it at all.
Others include:
- Hydra
Class: Hydrozoa
- Jellyfish
Class: Scyphozoa &
Cubozoa
- Sea anemones & Coral
Class: Anthozoa
48
Characteristics of Phylum Platyhelminthes?
Meaning: “Flat worms”
- c. 20,000 spp.
- Flatworms, flukes & tapeworms
- Free-living aquatic or parasitic
- Bilateral symmetry, flat body
- Acoelomates, with parenchyma
- Simple mouth, no anus
49
Examples of Phylum Platyhelminthes?
- Free-living flatworms, Class: Turbellaria
- Flukes, Class: Trematoda (endoparasites of mammals)
- Tapeworms, Class: Cestoda (endoparasites of mammals)
- Parasitic flatworms, Class: Monogenea (ectoparasites of fish)
50
Adaptations for Phylum Platyhelminthes parasitic life?
- Size and Shape = small, flat or cylindrical (pre-adaptation)
- Reduces sense organs
- Attachment organs
- Respire: Aerobic (non-parasites), Anaerobic (Parasites)
- Reproduction: Hermaphroditic (pre-adaptation), asexual (pre-adaptation), Planarian (non-parasitic)
51
Adaptation vs Pre-adaptation?
Adaptation - Has evolved as a result of a function
Pre-adaptation - Characteristic already present, but having it has made a function easier
52
What are the possible advantages of infecting secondary and tertiary hosts?
(Phylum Platyhelminthes parasitic life)
Increased reproductive potential
Increased range of the parasite in space & time
Intermediate host can promote infection of definitive host
53
How many Phyla does the Kingdom Animalia contain?
35 Phyla & about 1.5 M species described to date (95% invertebrates).
54
What is the oldest group of animals?
Porifera (lacking tissues, organs or symmetry. eg sponges)
55
Characteristics of Phylum Mollusca?
“molluscus = soft”
Snails, clams and octopuses (93,000 species)
Bilateral symmetry, coelomates
Mantle membrane secretes shell (some have lost the shell)
Muscular foot for locomotion
Head generally well developed; radula for feeding
Majority aquatic, some species able to live in land
56
What are characteristics of the class Bivalvia, within the phylum Mollusca?
"Bi = two, Valvia = valve"
Aquatic animals with 2 shell valves (bi-lateral symmetry)
Mostly sedentary or burrowing
Greatly expanded gills for filter-feeding and respiration
Separate sexes, fertilisation is external & free-swimming larva
57
What are characteristics of the class Gastropoda, within the phylum Mollusca?
"gastro = stomach, poda = feet"
Terrestrial and aquatic species
Head well developed for finding food; eyes, tentacles, etc
Asymmetrical body due to shell coiling & torsion
Herbivorous, carnivorous or scavengers
Separate sexes or hermaphrodite
eg Snails, slugs
58
What is torsion (in gastropods)?
twisting of the body in relation to head & foot brings the anus above the head, usually due to a shell
59
True / False
Snails have both male and female genitalia but still need to mate with another
True
Increases genetic diversity, and has diversity advantage than if they didn't mate despite having both genitalia
60
Mating in snails?
Elaborate and slow mating ritual
one snail will exchange sperm and a ‘love dart’ – mucus covered calcareous dart
61
Mating in snails: what are love darts?
secondary sexual characteristic
Shot from sex organs; covered in mucus
darter gains more fertilizations; darted dies sooner
62
What are characteristics of the Class Cephalophda in the Phylum Mollusca?
"cephalo = head, poda = feet"
Marine predators
Integral head & foot; tentacles, usually with suckers
Shell usually internal; "cuttlebone" of Sepia provides support and floating
Squids = elongated body, fins & "jet propulsion" for fast swimming
"Brain" in brain case
Separate sexes with courtship displays
63
Characteristics of the Phylum Annelida?
"annel = ringed"
Fan worms, bristle worms, earthworms & leeches (16,500 species)
Bilateral symmetry and segmented body, coelomates
Body covered with chaetae (bristles used for movement)
Marine, fresh water and terrestrial species.
Sexual reproduction (some able to regenerate).
64
Coelomate body plan advantages for Phylum Annelida?
- Hydrostatic skeleton
- Transport of excretory and sexual products
65
Metameric segmentation body plan advantages for Phylum Annelida?
Allow independent movement of different portions of muscles
66
Body covered with chaetae body plan advantages for Phylum Annelida?
Bristles help with movement
67
What are the three traditional classes of Annelida taxonomy?
Class: Polychaeta
Class: Oligochaeta
Class: Hirudinea
68
What are the characteristics of Class Polychaeta in Annelida taxonomy? (Traditional classification)
Many bristles
Marine annelids
Mobile and Sedentary species
69
What are the characteristics of Class Oligochaeta in Annelida taxonomy? (Traditional classification)
Terrestrial and aquatic annelids
Few bristles
70
What are the characteristics of Class Hirudinea in Annelida taxonomy? (Traditional classification)
Ectoparasites or predators
Few bristles
Some blood suckers
71
What are the new genetic evidence/classification groups in Annelida taxonomy?
Clade: Errantia
Mobile marine predators
Clade: Sedentaria
Marine sedentary worms
Earthworms
Leeches
72
What are characteristics of the Errantia (Annelida species)?
"Errant = travelling"
Marine species
Predators crawl on or burrow in the seafloor
Well defined head with eyes and jaws
Each body segment with prominent parapodia
Sexual reproduction with separate sexes
73
What are characteristics of the Sedentaria (Annelida species)?
Aquatic or terrestrial species
Earthworms are burrowers
Lug/fan worms are filter feeders
Leeches are ectoparasites or predators
Parapodia small or not present and few chaetae
Regeneration
Hermaphrodites
74
What is the function of the Cladogram phylogenetic tree type?
Cladogram - Node position indicates relative time but branch lengths arbitrary
75
What is the function of the phylogram phylogenetic tree type?
Phylogram - Branch lengths represent amount of change
76
What is the function of the dendrogram (ultrametric) phylogenetic tree?
Dendrogram (Ultrametric) - Nodes associated with specific geological time
