Adaptive Radiation and Convergent Evolution

Question 1

Adaptive Radiation

Answer 1

rapid speciation event into a multitude of new forms

Question 2

adaptive -

Answer 2

species vary in their microhabitat or food sources, adapt to their environment, convey fitness advantages

Question 3

radiation

Answer 3

lots of species, with a common ancestor, relatively short time period

Question 4

Niche

Answer 4

the specific place a species hold in its biotic and abiotic environment (physical temperature, role in food chain, interaction with organisms)

no two species can hold exactly the same niche in the same environment

Question 5

Creation of new/open niches (4)

Answer 5

mass extinction
new environment
key innovation traits
ecosystem engineering (Dams)

Question 6

Places of physical processes causing new niches

Answer 6

Galapagos volcanic islands
Rift lake in east Africa

Question 7

Cambrian explosion niches

Answer 7

massive radiation of new animal forms during the cambrian (Lasted ~20-25 MY)
rapid emergence of new traits, new environmental niches

Question 8

Angiosperm niches and their pollinators

Answer 8

coevolution with insect pollinators, pollinators greatly improved pollen transmission, both diversified

can travel much farther than wind-dispersed pollen (gymnosperms)

Question 9

How did angiosperms arise

Answer 9

first in forests dominated by conifers, but they grow faster, took pollinators from gymnosperms, dominated, changed landscape to favor their own growth

Question 10

Convergent evolution

Answer 10

independent evolution of analogous traits in two or more lineages
trait is not present in common ancestor!
ex: flight, venom injection, crab-like body plan

Question 11

Mechanism of convergent evolution

Answer 11

selection by the environment
same type of environment, different places
selection pressure is the same

Question 12

Mimicry

Answer 12

a non-toxic species evolving to resemble an dangerous one to deter predation

selection to look similar to scary things!

Question 13

Parallel evolution

Answer 13

similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure

ancestors did share the trait

ex: mammals and marsupials look similar despite split up a very long time ago

Question 14

The founder effect

Answer 14

the new population colonizing an island is the founder

small population size
lower genetic diversity than mainland populations, possibly an increased prevalence of rare/harmful alleles

this leads to faster evolution

Question 15

Faster evolution on islands and smaller populations because

Answer 15

small population, fewer genes in the overall gene pool (genetic drift is faster)

in a large population, large gene pool

Question 16

founder mutation

Answer 16

a new mutation in a small gene pool makes a larger overall contribution to genetic diversity compared to a large population

the greater the frequency of a gene, the greater change it will be passed on in the population

Question 17

Diversity of humans

Answer 17

Highest in Africa, lower in Europe, Lowest in Americas

greater proportion of rare alleles in African populations
low chance that rare allele will leave Africa, if it does, it could dominate easily