21- Contemporary Evolution

Question 1

what is contemporary evolution

Answer 1

= evolution that is happening in our life time (short period of time)

Question 2

what is natural selection

Answer 2

= differential reproduction of inherited traits

- results in adaption

Question 3

what is adaption

Answer 3

= match of form and function to the environment

Question 4

what is contemporary evolution associated with

Answer 4

• the same factors that are driving the current extinction crisis: habitat loss and degradation, overharvesting, exotic species

Question 5

what is directional selection

Answer 5

= a mode of natural selection in which an extreme phenotype is favored over other phenotypes –> causes the allele frequency to shift over time in the direction of that phenotype
- ex giraffe necks

Question 6

contemporary evolution: high selection pressure

Answer 6

• extinction rates 1000x higher than background rates
• we’re changing things so dramatically that species cannot adapt
• very strong selection pressure –> killing lots of different animals

Question 7

example #1 of things that humans are doing that act as selection pressure: overharvesting

Answer 7

• over harvested fish populations –> smaller fish
• over hunted big horn sheep –> hunters taking the bigger horns = human induced selection
• over hunting of elephant tusks –> now male and female elephants both born without tusks

Question 8

example #2 of things that humans are doing that act as selection pressure: fragmentation

Answer 8

Effects of fragmentation:

1. direct effects
   - not enough area
   - less resources
2. limited dispersal
   - inbreeding depression
3. reduced foraging abilities
4. edge effects
   - microclimate
   - wind
   - fire
   - predation
5. cascading change

Question 9

evidence of rapid evolution in plants

Answer 9

• weeds of crops evolve resistance to herbicides within a few generations

Question 10

many plant species have evolved in response to CO2 increase (kibale plant story)… is this evolution?

Answer 10

Study in kibale shows that increased temperature/rainfall/CO2 = decreased protein, increased fiber, increased tannins in plants.
Is this evolution? No
- if its the same individual then its not evolution
- just one plant’s response to changes in environmental conditions

Question 11

what is habitat fragmentation

Answer 11

= the process whereby a large continuous area of habitat is both reduced in area and divided into fragments

Question 12

what is metapopoulation

Answer 12

= a group of populations that are separated by space but consist of the same species

Question 13

how has climate change affected British flowering plants

Answer 13

• the average first flowering date of 385 British plant species has advanced by 4.5 days during the past decade compared with the previous 4 decades

Question 14

what are characteristics of emerging infectious diseases

Answer 14

• recently increased in incidence
• recently increased in geographic range
• recently moved into new host populations
• recently been discovered
• are cause by newly-evolved pathogens

Question 15

are infectious diseases today emerging at an accelerated rate? reasons to be skeptical

Answer 15

reasons to be skeptical:

1. improved diagnostics
2. improved surveillance
3. increased media attention and public awareness
4. increased attention by scientists capitalizing on #3

Question 16

possible cause for new emerging diseases

Answer 16

new emerging diseases may be due to anthropogenic environmental changes that create conditions favourable for transmission between humans and primates