Ch. 16, 17, 18 Evolution

Question 1

how do we know evolution exist?

Answer 1

by studies in anatomy, embryology, molecular biology, and biogeography

Question 2

how evolution leads to natural selection

Answer 2

• some traits of an individual are more adaptive to changing environment
• more offspring are produced with favorable genes so the resources, reproduction and survival are limited

Question 3

Charles Darwin

Answer 3

along with Wallace, came to the idea of natural selection around 1858
- published a controversial “On the Origin of Species”

Question 4

adaptation

Answer 4

a heritable trait that helps the survival and reproduction of an organism in its present environment

Question 5

the basis of variation

Answer 5

genetic variation

Question 6

types of genetic variation

Answer 6

• dimorphic

- polymorphic

Question 7

dimorphic trait

Answer 7

traits with 2 distinct forms: white or purple flowers on pea plants

Question 8

polymorphic trait

Answer 8

traits with more that 2 distinct forms: ABO blood type in humans

Question 9

basis of genetic variation

Answer 9

mutation (change in DNA pattern)

Question 10

mutation types

Answer 10

• neutral: no effect on survival or reproduction
• lethal: ends in death
• beneficial: gives slight advantage toward survival and reproduction

Question 11

sources of mutations

Answer 11

• random genetic changes
• crossing over in Meiosis I
• independent assortment in Meiosis I
• fertilization

Question 12

gene pool

Answer 12

sum of all genes in a population

Question 13

allele frequency

Answer 13

rate at which a specific allele is present within a population

Question 14

microevolution

Answer 14

change in allele frequency in gene pool

-always occurring in natural populations due to mutations and/or natural selection

Question 15

macroevolution

Answer 15

large scale evolutionary pattern above the species level

-ex. land plants evolving from algae, extinction of dinosaurs

Question 16

the two main evolution types

Answer 16

• divergent evolution

- convergent evolution

Question 17

divergent evolution

Answer 17

changes in body or form from a common ancestor

ex. homologous structures (limbs of vertebrate animals)
- flight in birds and bats
- flippers in penguins and porpoises

Question 18

homologous structures

Answer 18

structures in organisms that share the same basic form

• same genes direct their development
• may be used for different purposes

Question 19

vestigial structures

Answer 19

structures that exist in organisms but seem to have no apparent function

• -appear to be residual parts from a past common ancestor–
• ex. appendix in humans, pelvis on snakes, goosebumps

Question 20

convergent evolution

Answer 20

when traits evolve similarly in species that do not appear to have a common ancestor
-have analogous structures
due to similar selection pressures
-may perform the same function because of environment pressures

Question 21

analogous structures

Answer 21

structures that look alike but evolved independently

Question 22

transitional soforms

Answer 22

an intermediate form of an organism linking two other organisms together

Question 23

patterns of natural selection

Answer 23

• directional selection
• stabilizing selection
• disruptive selection

Question 24

directional selection

Answer 24

an extreme trait is more favorable

Question 25

stabilizing selection

Answer 25

an intermediate trait is more favorable

Question 26

disruptive selection

Answer 26

extremely different traits are more adaptive and favorable

Question 27

natural selection and diversity

Answer 27

sexual dimorphism different looking male and females - due to sexual selection: traits to better attract mates females either choose mate(s) or males compete for a group of females

Question 28

balanced polymorphism and the heterozygote

Answer 28

two or more alleles continue circulating at a relatively high frequency in a population - arises in nature favoring the heterozygotes ex. sickle cell anemia and malaria resistance

Question 29

the level of genetic variance

Answer 29

- are best maintained with sexual reproduction as genetically different parents create diverse children - best to avoid asexual reproduction which leads to clones

Question 30

non-selective evolution (evolution by "chance")

Answer 30

- genetic drift | - fixed allele

Question 31

genetic drift

Answer 31

random chance in allele's frequency over time, brought by chance alone -by chance to be in the right place at right time or wrong place wrong time

Question 32

type of genetic drifts

Answer 32

- bottleneck: results in large part of the population getting wiped out - founder effect: small group establishes a new population

Question 33

fixed allele

Answer 33

individuals for allele are all homozygous | -common among small populations

Question 34

gene flow

Answer 34

movement of alleles between populations | -can result in change or stabilization of allele frequencies

Question 35

speciation

Answer 35

evolutionary process in which new species form - occurs when populations cross breed (not interbreed) - increase the number of genetic variation/differences - over time they become so different we call them different species

Question 36

types of speciation

Answer 36

- allopatric speciation - parapatric speciation - sympatric speciation

Question 37

allopatric speciation

Answer 37

arises from physical separation between populations - reproductive isolation - geographic isolation

Question 38

reproductive isolation

Answer 38

biological/physical barrier gene flow * influenced by how an organism reproduces - can prevent interbreed--even if populations meet again - -have pre-zygotic and post-zygotic factors

Question 39

geographic isolation

Answer 39

physical geographical barriers to gene pool | *influenced by how species travel

Question 40

hybrid

Answer 40

cross between 2 different species that are similar

Question 41

sympatric speciation

Answer 41

populations inhabiting same regions with no physical barriers between them - can occur in single generations when chromosome number multiplies -also occurs with no number change more common in plants

Question 42

parapatric speciation

Answer 42

adjacent populations speciated despite being in contact across common borders - divergences spurred by local pressures are reinforced ex. velvet walking worm - hybrids that are formed in contact zone are not better fit

Question 43

adaptive radiation

Answer 43

organisms that do not go extinct may go under adaptive radiation - key innovation - co-evolution

Question 44

key innovation

Answer 44

new trait that allows one organism to exploit a habitat more effectively

Question 45

co-evolution

Answer 45

two species evolve jointly because of close ecological connection