Animal Diversity

Question 1

What are the 3 domains of life

Answer 1

Bacteria
Archea
Eukaryotes

Question 2

The Tulgrin funnel

Answer 2

Separates micro arthropods from soil sample
Funnel with mesh cover
Soil placed on mesh
Warm light bulb drys out sample
Micro arthropods drop through mesh and are collected at the bottom of funnel tube

Question 3

Metazoa =?

Answer 3

animals

Question 4

How many animal species?

Answer 4

> 1.1 million described
9.92 million actual = 88% undescribed
However losing species at concerning rate

Question 5

Criteria for an animal

Answer 5

Multicellular
Large (compared to protozoans)
Heterotrophic
Motile
Body polarised along anterior-posterior locomotor axis
Muscle/nervous system
Epithelia
Extracellular matrix + connective tissue
Conserved extracellular signalling pathways
Sexual reproduction

Question 6

Why does sexual selection exist

Answer 6

1. Reduction of deleterious mutations
2. Rapid adaptation to changing environment
3. Parasite-host coevolution in maintenance of sexual reproduction
   - some animals asexual and sexual to influence offspring gender

Question 7

E.g. of sexual and asexual life cycle in one animal

Answer 7

Daphnia
Predominantly asexual = females
In times of stress, crowding and unfavourable conditions cycle is sexual = increase in males

Question 8

From what did animals evolve?

Answer 8

collared Choanoflagellate like ancestor
- single celled org
- flagellum inside microvilli: stirs surrounding water to bring in nutrients that get trapped
Hypothesised by looking at current day similar orgs

Question 9

What was the first animal thought to be?

Answer 9

lived >600MYBP
May have resembled Trichoplax
- only member phylum placozoa
- 2 layers of cells, 6 cell types
- fission reproduction but evidence of gametes
- no gut, absorbs microorgs then lyses
- has homologous for 83% gene families but also found in sea anemone and Bilaterians

Question 10

First evidence of life

Answer 10

Early archaea

Question 11

First animal (time period)

Answer 11

Early paleozoic era

Question 12

Describe first animal fossils and when they formed

Answer 12

Formed Proterozoic era

• soft bodied
• marine
• suspension or detritus feeders
• relationship to extant phyla unclear … may have been Cnidaria

Question 13

Sudden diversification of animals

Answer 13

Cambrian period

Phenotypic and molecular change

Question 14

Describe Cambrian explosion and why it happened when it did

Answer 14

• diversification of animals, mostly marine
• hard body parts = helped with fossil record
• clear predation in some animals

Happened because;

• seas more oxygenated via photosynthesis
• oxygen toxic to many orgs = extinction
• break up of Pannotia = increased shallow seas
• more potential niches available than in deeper oceans

Question 15

Pannotia

Answer 15

• Supercontinent in Southern Hemisphere
• broke up 750MYA = shallow seas
• Pangea developed afterwards

Question 16

Homologous

Answer 16

Characteristics are shared and evolved from common ancestor

Question 17

Analogous

Answer 17

Species dont share common ancestor despite common characteristic
E.g. bats and insects both have wings

Question 18

What causes evolution

Answer 18

• speciation events

- species divergence

Question 19

2 E.g.s of analogous species

Answer 19

1. Placental and marsupial mammals
   - Australian marsupial radiated in isolation from placentals
   - convergent evolution from similar selection pressures
2. Barnacles and limpets
   - armoured covering has different origins
   - phenotypic convergences: selection pressure from wave/current action
   - barnacles are homologous with crabs though

Question 20

Why might taxa resemble eachother

Answer 20

• characteristic arose early in ancestry of taxa before MRCA
  E.g. jaws on amphibians, reptiles, birds and mammals
  2. Originated from MRCA
  E.g. amniotic egg fro reptiles, mammals and birds
  3. Convergence

Question 21

Homoplasy

Answer 21

Similarity in characteristics due to convergence