Rates and patterns of evolution

Question 1

Evolution definition

Answer 1

the change in heritable characteristics of populations over successive generations

a change in frequency of different alleles (gene variants) in a population

Question 2

Microevolution –> macroevolution

Answer 2

micro - within a population, accumulation of small changes, can be on small time scale

macro - evolution over geological time (new species)

Question 3

Taxon

Answer 3

scientifically classified group

seen in phylogeny

Question 4

Trait

Answer 4

observable feature in the phenotype of an organism

physical, physiological, behavioral

Question 5

Are all traits equally likely to have viable mutations? how fast, how common?

Answer 5

No!
most mutations are fatal, change organs

mutation in for a trait that is controlled by multiple genes (height), one mutation will not change phenotype

different areas of genome more vulnerable to mutations

Question 6

How fast do traits evolve?

Answer 6

traits that are under heavy selection from the environment evolve faster than genetic drift

typically, evolve slowly

Question 7

do species become more complex over time?

Answer 7

massive amount of variation of size of genome in organisms

after unicellular –> multicellular eukaryotes
species don’t necesarrily become more complex over time

Question 8

Complexity evolution

Answer 8

general trend towards specialization in traits over time
lose generalized traits to become better adapted to a very specific niche

ex: orchid and mycorrhizae symbiosis

Question 9

Can a species regain a trait if it is lost through evolution?

Answer 9

rare but expression can be turned on and off so easier to regain trait

organisms retain genes that are turned off

Question 10

Irreducible complexity

Answer 10

traits whose functions have become so essential to life, losing them through evolution seems impossible (ex: pikia development of the spinal column)

Question 11

Key Innovations of trait evolution

Answer 11

flight, hard bodies, seeds

Question 12

The island rule

Answer 12

lots of allopatric speciation
change size, either larger or smaller

smaller mainland animals get bigger, bigger animals get smaller

basically, selection pressure (especially for size) changes as there are no predators

Question 13

Insular Dwarfism

Answer 13

selection for large body size in herbivore is reduced
because prey tends to be smaller on islands
and not as many predators (large bodies scare predators)

Question 14

Insular gigantism

Answer 14

new carnivore species can become larger to fill the niche of apex predators

Question 15

taxonomic rates of evolution

Answer 15

calibrated with fossil record, compare the number of changes
molecular clock (DNA sequences evolve at a rate that is relatively constant over time and among organisms)
not constant over time

Question 16

Creeps

Answer 16

Creeps = gradual speciations
many intermediates, a little different every time
intermediate forms convey an advantage of some kind changing environment

Question 17

Jerks

Answer 17

punctuated equilibrium (big change, then not a lot of change in quick period of time)
mutations severe to cause noticeable changes in phenotype

need reproductive isolation, more stable environment

Question 18

Living fossils

Answer 18

punctuated equilibrium
very little change in the deep ocean, for example

species are adapted to their habitat, if their habits remain stable over time, species tend to remain stable
no extinction or evolution