Phylogeny 3 Flashcards
1
Q
how big is the tree of life
A
- very big: almost any species has a vast and dense phylogenetic neighbourhood
2
Q
how many species are currently described in the tree of life
A
- about 2 million species
3
Q
systematics (2)
A
- field that reconstructs phylogenetic relationships
- we have a good idea of the broad phylogenetic relationships of species we have discovered, but most species are still unknown
4
Q
how well do we know the leaves of the Tree of Life (2)
A
- not very well as most species on Earth are still undiscovered, and even the ones we have discovered have not been studied intensely
- we should expect at least 20 million species on Earth, meaning we have only discovered 10% or fewer of the species on Earth
5
Q
how well do we know the tree of life in general
A
- reasonably well in broad structure, but the details are poorly known in most subgroups and most species remain to be discovered
6
Q
arthropods
A
- include insects, spiders, and crustaceans
7
Q
echinoderms
A
- include sea stars, sea urchins, sea cucumbers
8
Q
nucleus and sex
A
- characteristic of all eukaryotes
9
Q
muscle cells
A
- characteristic of all animals
10
Q
head
A
- characteristic of all animals, except for jellyfish & corals
11
Q
skeleton with backbone
A
- characteristic of all vertebrates
12
Q
legs
A
- characteristic of all tetrapods
13
Q
eukaryotes (6)
A
- animals, plants, fungi, algae, ciliates, and other protists
14
Q
what is red algae close to
A
- green algae
15
Q
what is fungi close to
A
- animals
16
Q
what are ciliates close to
A
- brown algae
17
Q
what is archaea the sister group to
A
- eukaryotes
18
Q
what is bacteria the sister group to
A
- all the rest of life
19
Q
how characteristics can we use to memorize plant phylogeny (3)
A
- on land: mosses, ferns, conifers, flowering plants
- vascular system: ferns, conifers, flowering plants
- seeds: conifers, flowering plants
20
Q
which animals lack a head
A
- jellyfish and corals
21
Q
which clades are close and share spiral cleavage in animal phylogeny
A
- molluscs (snails, squids, clams), arthropods, and nematodes
22
Q
what are echinoderms close to
A
- vertebrates
23
Q
within vertebrates, which clades are not included within tetrapods (3)
A
- fish (have fins and not legs): sharks, rayfinned fishes, and lungfish
24
Q
what are frogs and salamanders the sister group to
A
- amniotes
25
what are mammals the sister group to
- lizards & snakes, birds, and turtles
26
why are model organisms used to understand humans
- they are an attempt to reconstruct the traits of our ancestors
27
what is the time scale of evolution
- millions of years; depicted by the "geological time scale"
28
what are the major stages of the "geological time scale" (4)
1. precambrian (4600 - 540)
2. paleozoic (540 - 252)
3. mesozoic (252 - 66)
4. cenozoic (66 - 0)
29
precambrian era
- mostly single-celled organisms and not much on land
30
what were the main events of the precambrian era (4)
1. origin of earth (4.6 mya)
2. origin of life (4 bya)
3. oxygenation catastrophe (2.4 bya)
4. origin of multi-cellular animals (0.7 - 1 bya)
31
the oxygenations catastrophe (3)
- life's first major environmental disaster
- the anaerobic world flipped to primarily aerobic because of photosynthesis producing oxygen
- 2.4 bya
32
what was the major event of the late precambrian era
- multicellular animals appearing
33
what were the major events of the paleozoic era (2)
- cambrian explosion
| - plants & animals on land; first tetrapods
34
cambrian explosion
- early paleozoic era
| - marine animal fossils suddenly became abundant: arthropods, chordates, molluscs all present
35
what is characteristic of the mid-late paleozoic era
- abundant life on land due to the appearance of tetrapods 395 mya
36
what is the main event of the mesozoic era
- origin of dinosaurs and mammals
37
what is the main event of the cenozoic era
- the origin of hominids where primates evolved
38
how deep is the tree of life
- 3-4 billion years deep, but diversification of familiar multicellular organisms happened mostly in the last 600 millions years
39
how do we treat fossils when studying phylogeny
- we link fossils through strata to explain morphological changes most simply; we end up treating fossils like living species
