topic 3

Question 1

where do we find evidence of evolution? two major processes?

Answer 1

evidence of evolution 
	• From phylogenetic and comparative studies 
	• Two major processes of evolution 
	• Cladogenesis 
anagenesis

Question 2

describe cladogenesis

Answer 2

○ Branching of a lineage into two or more descendant lines

○ Evolution that results in the splitting of a lineage

Question 3

describe anagenesis

Answer 3

○ Evolutionary change of various characteristics in each descendant
○ Evolution within a lineage
○ Can lead to pseudoextinction

Question 4

define pseudoextinction

Answer 4

Pseudoextinction: a phenomenon in which a taxon changes by anagenesis over evolutionary time, until it is so different from the ancestor that it is reclassified as a new taxon

Question 5

describe rates of evolution - conservative and mosaic

Answer 5

Characters evolve at different rates - two species may differ in some features but not in others
• Conservative characters
○ Little or no change over long periods
• Mosaic evolution
○ Evolution of different characters at different rates within a lineage
○ Ancestral and derived characters differ among lineages
○ Any species is a mosaic of plesio- and apomorphic features

Question 6

what is homoplasy?

Answer 6

• Common in nature
○ Independent evolution of a character/character-state
○ Includes convergence/parallelism & evolutionary reversal
• Convergence
○ Similarity not inherited from a common ancestor
○ • Nearly identical function achieved independently
○ Ex. Vertebrate vs. cephalopod eye
○
Vertebrate vs.. cephalopod eye
3e Fig. 3-4 (see4e, Fig. 2*0)
o Vertebrate eye with blind spot: small, circular, optically
insensitive region in the retina where fibers of the optic nerve
emerge from the eyeball. It has no rods or cones.
in cephalopods the axons run directly from the base of the retinal cells into the optic ganglion

Question 7

describe parallelism

Answer 7

c Similar developmental modifications 
that evolved independently 
Often in closely related species, i.e., 
species sharing most recent common 
ancestor 
Some consider this as another form of 
C 
convergence 
Raptorial feet from perching feet in 
owls and falcons

Question 8

describe evolutionary reversal

Answer 8

reversal 
Return from an "apomorphic" to a 
"plesiomorphic" state 
c Loss of wings in many winged insect 
lineages 
Original plesiomorphic state: wingless

Question 9

what is heterochrony and who first described it

Answer 9

• Concept first proposed by Haeckel in 1875
○ To describe cases in which an ontogenetic sequence of events did not recapitulate the phylogenetic sequence
• Evolutionary change in phenotype caused by an alteration of timing of developmental events (futuyma, 2013)
• Change in the relative timing of developmental events in one species relative to an ancestral species
• Ex. Skeletal maturity in humans
○ Chinese and japanese reach full maturity earlier than africans and much earlier than humans
○ Result = shorter final height and different pattern of skeletal maturation
• May lead to changes in size and shape
○ Paedomorphosis/paedogenesis

Question 10

paedomorphesis

Answer 10

• Paedomorphosis
• Conditions in which a larva becomes sexually mature without attaining adult form
•

Question 11

neoteny

Answer 11

• May result from a retardation of somatic development relative to sexual development
Ex. Salamanders
Most tiger salamanders (Ambystoma tigrinum)
C
undergoes metamorphosis
c Adult axolotl (A. mexicanum) resemble larva of
its relative; remains aquatic
Some A. tigrinum population can also show
C
neoteny
Related to iodine in the diet

Question 12

progenesis

Answer 12

• Less common, from an acceleration of sexual development relative to somatic development
• Cessation (stop) of growth at an earlier age
• Ex. Tiny salamanders
Fron al & panetal Dones
juvenile stage
Abbreviated development

Question 13

what is adaptive radiation? ex?

Answer 13

• Evolutionary radiation 
	• Diversification into forms filling different ecological niches 
	• Evolution of phenotypic and ecological diversity within a multiplying lineage 
	• Possibly the most common pattern of long-term evolution instead of sustained, directional selection 
	• Ex. Darwins finches 
Darwin's finches at the 
Galapagos (14 species) and 
Cocos Islands (1 species) 
z Ancestor arrived from mainland 
Of South America ca 2.3 Myr ago 
Different dietary adaptations — 
different bill morpholow

Question 14

species flock

Answer 14

• A group of closely related species all living in the same ecosystem
• Should be applied to species assemblage of monophyletic origin
• Evolved within the same ecosystem fr4om a single ancestral species by repeated speciation events
One or more synapomorphies in all members

Question 15

ex of species flock

Answer 15

Three rift lakes of east africa Rift lake 
Formed due to 
tectonic movements 
of continental crust 
African rift lakes 
C 
Origin dates back to 
—12 mya with the 
formation of Lake 
Tanganyika 
'chichlids
Great Lakes of Africa 
• Debates about the causes of 
the speciation (allopatric vs. 
sympatric) 
• Distinctive behaviours, diets , 
and morphologies 
• Lake Victoria: —400 kya; 
>200 species 
• Lake Tanganyika: —12 mya; 
at least 140 species 
• Lake Malawi: — 1-2 my-a; 
—1,000 species 
• Feeding regimes 
• Insects, detritus, algae 
attached to rocks, phyto- & 
zooplankton, molluscs, 
small fishes, large fishes, 
even fish scales

Question 16

adaptive radiation - mimicry

Answer 16

defense against predators

Question 17

mullerian mimicry

Answer 17

• Defense against predators 
	• Mullerian mimicry 
		○ Both species distasteful or poisionous 
		○ In roughly equal proportions 
		○ Both benefit 
• e.g., Heliconius erato and H. 
melpomene 
If two species were confused 
with one another by a 
common predator, 
individuals in both would be 
more likely to survive

Question 18

batesian mimicry

Answer 18

○ Model species venomous, poisonous, or distasteful
○ Mimic usually in smaller numbers than its model
○ Only mimic benefits (not poisonous)

Question 19

pseudocopulation

Answer 19

○ Australian orchid mimics female wasp

○ Male wasp tries to copulate, pollinating the flower