patterns of evolution

Question 1

macroevolution

Answer 1

speciation events or splits from a lineage

Question 2

microevolution

Answer 2

changes within a species or within a lineage

Question 3

the fossil record - problems

Answer 3

• new branches should appear to be gradual as microevolutionary changes accumulate
• but in fossil recoed new species appear suddenly

explanations :

1. major gaps in fossil record - gradual transitions ar absent
2. evolutionary chnages happen suddenly in short bursts

Question 4

punctuated equillibrium

Answer 4

the idea that evolution occurs in spurts instead of following the slow, but steady path that Darwin suggested

Question 5

phyletic gradualism

Answer 5

model of evolution which theorizes that most speciation is slow, uniform and gradual

Question 6

phylogeny

Answer 6

the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms

Question 7

adaptive radiation

Answer 7

rapid increase in the number of species with a common ancestor, characterized by great ecological and morphological diversity

Question 8

convergent evolution

Answer 8

the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities

Question 9

analogous characters

Answer 9

having similarities in functions but different evolutionary origins

Question 10

homologous characters

Answer 10

derived from the same common ancestor

Question 11

co-evolution

Answer 11

the process of reciprocal evolutionary change that occurs between pairs of species or among groups of species as they interact with one another

happens when two or more species directly influence each other’s evolution = exert selection pressure on each other

Question 12

co-adaptations

Answer 12

the process by which two or more species, genes or phenotypic traits undergo adaptation as a pair or group

Question 13

trilobites and predators ( arms race )

Answer 13

• hard exoskeleton appeared in Cambrain arthropods
• the sea became dangerous at the time
• trilobites under strong selection pressure to avoid predatation

Question 14

fossils

Answer 14

1. transformed body parts
   - shell, bones, teeth
2. activity ( ‘trace fossils’ )
   - burrows, footprints
3. preserved remains ( ‘sub fossils’ )
   - shells, remains in amber
4. organic cheicals
   - any body parts

Question 15

step one : how fossils are formed

Answer 15

body survives long enough after death to undergo fossilisation

• soft parts are destroyed quickly
• few fossils of soft bodied organisms
• even hard parts are likely to be destroyed

Question 16

step two : how fossils are formed

Answer 16

remains must become buied in sediment at the bottom of a water column

• fossils are only found in sedimentary rocks

the chance of fossilisation depends on proxiity to sediment

• terrestrial = low
• in water/on sediment = medium
• in sediment = high

Question 17

step three : how fossils are formed

Answer 17

permineralization

• sediement covered by more layers
• compacts into rock - may deform or destory the fossil
  (or)
• hard minerals leach out and rocks impregnate the remains
• original compounds replaced and leach out

Question 18

step four : how fossils are formed

Answer 18

exposure ( the ‘unlikely’ event )

• fossil means something dug up
• tectonic pressures can move the fossil around
• re-expose it in a terrestrial area
• can also be lost forever

Question 19

radio-carbon dating - dating fossils

Answer 19

• 5730 years after death 1/2 the C14 to N14
  ( C14 half life = 5730 )
• can work out date of death by examining the ratio
• only for fossils up to 40,000 years

Question 20

volcanic ash - dating fossils

Answer 20

• many sediments contain volcanic ash (‘tephra’)
• Potassium and Argon ( unstable isotopes ) in ash
• decay ore slowly that C14 - fossils older than 100,00 years

Question 21

paleomagnetic dating - dating fossils

Answer 21

• currents in Earths core change direction of magnetic field ‘normal’/’reserved’
• determines allignment of magnetic particles when rocks form
• age rocks by comparing the polarity to cores of rock from sea bed

Question 22

relative dating - dating fossils

Answer 22

compare fossils to fossils of known age and other strata that lookk similar

Question 23

paleontology

Answer 23

study of fossils

Question 24

Cretaceous

Answer 24

65 - 144 mya

extinction of most dinosaurs

Sinosauropteryx ( dinos )
- melanosomes : contain the pigments in hairs and feathers

Question 25

Jurassic

Answer 25

144 - 206 mya ' quarry dinos ' very large herbivores 4 species, up to 26m, estimated weight 50 - 113 tonnes

Question 26

Triassic

Answer 26

206 - 251 mya ichthyosaur ( 'fish lizard ' ) evolved from terrestrial reptiles that returned to the sea predated earliest dinosaurs by 20 my just before last dinos cetaceans were not the first group to return to the sea

Question 27

Permian

Answer 27

251 - 290 mya terrestrial tetrapods, arthropods, plants and algae fusulinds - protists with a hard shell ammonites - molluscs with a hard shell

Question 28

Carboniferous

Answer 28

290 - 354 mya coal deposits due to apperance of bark bearing trees no lignin digesting bacteria atomspheric O2 80% higher than today allowed gigantism to evolve on land and in the sea

Question 29

Devonian

Answer 29

354 - 417 mya lungfish ( first appeared ) - ansestor of tetrapods tetrapod colonisation of land first fossil insects first angiosperms ( flowering plants ) ``` Rhynie Chert ( sedimentary deposit ) - contains evidence of vascular plant and fungal filaments growing in plant tissue ```

Question 30

Silurian

Answer 30

417 - 443 mya cooksonia, one of the earliest terrestrial plant fossils

Question 31

Ordovician

Answer 31

443 - 490 mya Naultiloids - shell producing cephalopods straight or curled shells - divided into chambers - extant species

Question 32

Cambrian ' expolosion '

Answer 32

490 - 543 mya Trilobites - heavily armoured marine arthropods - earliest example of animals using weapons - rapid evolution - 15000 + species recognised - 9 orders - most animal classes first appear in the Cambrian