Chapter 23

Question 1

evolution

Answer 1

• change in genes over time
• heritable change in one or more characteristics of a population or species from one generation to the next
• heritable change- mutation from parent to offspring

Question 2

mircoevolution vs. macroevolution

Answer 2

• micro- small, one generation to next

- macro- large scale, longer periods of times, species change over a very long period of time

Question 3

Charles Darwin

Answer 3

• deserves primary credit for theory of evolution
• developed existing ideas about descent with modification
  
  • plus provided lots of evidence to support it
  • species change over time that evolve from other species
• first to observe that natural selection is the main process driving evolution
  
  • driving force of evolutionary process, what makes evolutionary theory a theory because it is an explanation process and how it actually happens over time, it is the idea that certain traits are more favorable in certain environments and if you have those traits you are more likely to survive, reproduce and pass traits to offsprings

Question 4

Erasmus

Answer 4

• darwins grandfather
• said “all warm-blooded animals have arisen from one living filament”
• people thought of evolution at the time, idea we have simple life forms and over time new life forms arise and are able to do more
  
  • life started out as a single cell like prokaryotes

Question 5

Jean-Baptiste de Lamarck

Answer 5

• inheritance of acquired characteristics
• had problems because we did not know much about inheritance
  
  • dont know how traits pass from parents to offspring or about genetics
• example: how giraffes got such long necks- thought since giraffes spend so much time stretching their necks then you stretch it out over life and you acquired a longer neck and that gets passed down to offspring and there neck gets a little longer then it passes again
• he is wrong because of acquired traits, if you acquired new traits in your life those are not heritable

Question 6

HMS Beagle

Answer 6

• Darwin was on board a famous ship for 5 years as a naturalist
• purpose of the trip was to map out new trade routes
• as a naturalist- at all the stops he had to collect specimen and catalogs it and categorizes all of it. the birds and plants he had seen

Question 7

The Galapagos

Answer 7

• one of Darwins stops
  -noticed a lot of different specimen
  found that there were 14 different types of finches and that species are similar to those on the main content but have unique structures
• he noticed that across islands in the galapagos that tortes all have different features

Question 8

Darwins Finches

Answer 8

• in Galapagos he collects all different finches and doesn’t know there from the same species
• noticed as collecting that depending on food they have different beak shapes
• large ground finch has large beak to crack nuts
• probing beaks have to get insects
• variation in beak shape is an adaptive research

Question 9

Darwins Insights

Answer 9

• understood descent with modification
  
  • 2yrs after returning, figured out that natural selection was driving “branching”
• species change over time, they evolve from other species
• thought about how we get diverse species- now he puts together for natural selection
• has to do with favorable traits
• all different finches population diverge into all different species as they adjust to the conditions
• branching- slitting off and making new species
  
  • picture- branching, evolution is like species turning into new species with a very linear process
• finch species- each one has there own ancestor but now they say NO it is all from the same ancestor and diverge into new species- means we can have a lot more species to develop in a short time
• single ancestor can give rise to several descendants
• solved evolution and biology
• thinks of evolution as a branching tree

Question 10

Evolution of monkeys to humans

Answer 10

• species diverge from new species and not a linear process
• linear picture is one species turning into another
• no modern monkery around today is that of an ancestor of humans
• more accurate to say that humans and monkeys share a common ancestor- some diverge into monkey groups others into ape groups

Question 11

Darwins writing; 2 main points

Answer 11

• he wrote “On the Origin of Species by Means of Natural Selection
• he wrote an elaborate manuscript that he didn’t publish for years
• waits till after trip
• was afraid to publish because he knew he had something but had a bad life

main points:

1. species were not created in their present form, but evolved from ancestral species
   
   • descent with modification- species change over time and species evolve from other species
2. proposed a mechanism for evolution: natural selection
   
   • how species change over time- natural selection
   • nature selecting for favorable traits giving certain individuals advantages over others

Question 12

Alfred Russel Wallace

Answer 12

• english naturalist
• came up with same ideas as darwin
• he is a codiscoverier of natural selection
• he wrote to darwin saying he came up with this idea and wanted his input
• they decided to both write essays and present at the same conference
• presented to the world in a room scientist and they didn’t care much for it
• 2nd part was natural selection being the driving force of evolution was not accepted at first
• time they were figuring out DNA and this is when Darwin’s theory came back into light of natural selection

Question 13

Controversy over Natural Selection

Answer 13

• Hypothesis: natural selection is most important process underlying evolution
  
  • not fully accepted until mid 20th century
• not accepted for years because genetics wasn’t discovered yet
• time they were figuring out DNA and genes
• Darwin came back in
• natural selection hinges on favorable traits being passed from parents to offspring and if you cant explain inheritance then it was hard to get on board with natural selection

Question 14

evidence of biological evolution

Answer 14

• studies of natural selection
• fossil record
• biogeography
• convergent evolution
• selective breeding
• homologies
  
  • anatomical
  • developmental
  • molecular

-just one alone is not complete
table 23.2*

Question 15

fossil record

Answer 15

• fossils from same evolutionary periods consistently found together in geologic strata
• “transitional forms”
  
  • ex. “fishapod”
  • in-between fossils- tiakkti real name
  • fishapod- in between fish and tetrapod- used to be completely aquatic, broad scale and fish body
  • keep finding animals like this, gives a nice progression of how you start with a fish and end with an amefibin
• not a complete picture of life on earth
• fossilization is a very rare event
• chances of every organism to become fossilized is very low
• you have to die the right way, in the right environment and then become buried
• microscopic able to see them
• can look inside of the embryo
• fossil record is in complete

Question 16

example: whale evolution

Answer 16

• whale and dolphin are part of mammals
• started on land but some returned to ocean
• seals and sea lions
• go back in time ancestor of whales and used to look like a wolf size and over time gives rise to whale
• fossil record allows you to track it in time
• they have tiny hip bones and track the limbs and vibration of nostrils

Question 17

Biogeography

Answer 17

• the study of geographical distribution of extinct and modern species
  
  • studying distribution of organisms- species over the planet and where you find them
  • are isolated in certain area
• isolated continents and island groups especially insightful
  
  • endemic- species you find in one place of world- Madagascar- birds all mammals, only found here and are evolving in the absence of any other genes coming in here
• piece together information about the past

Question 18

Biogeography: marsupials

Answer 18

• evolution correlated with known changes in land masses on the Earth
  -ex. Australia and mammalian evolution
• all land masses are connected
  -Australia- cut off from these land masses, this helps tell the story of mammals- unique that is has a ton of marsupials- mammals and pouches to carry babies them, they are early mammal groups
  -Placental mammals didn’t evolve till late
  -Australia broke
  Only one to get placental is bats and all mammals there are marsupials

Question 19

Convergent Evolution

Answer 19

• gives rise to analogous structures
• organisms from different evolutionary lineages being to resemble one another and have different characteristics that begin to resemble one another
• Analogous structure- features that organisms have in common not due to a common ancestor but because they are under similar selective pressures in their environment
• example: wing of bird vs. bat wing- same shape, not because they inherited it from a common ancestor but because if you are a vertebrate that flies due to similar selective pressures in their environment
• laws of physics say thats how you make something that flies, the shape of it whether it is a bird or mammal
• similarities due to natural selection, selecting similar features due to same types of environments

Question 20

Analogous structures

Answer 20

features that organisms have in common not due to a common ancestor but because they are under similar selective pressures in their environment

Question 21

Selective breeding/artificial selection

Answer 21

• possible due to genetic variation
• breeders choose desirable phenotypes
• people for the selecting (plants, animals)
• Darwin used examples from this to provide support for evolutionary theory
• difference between NS and AS is who is doing the selecting
• rare materials of both is the fact that there is genetic variation in a given population- group of wolves vary genetically, not all clones
• due to genetic variation you can focus in on traits and create a lot of diversity
• AS tends to happen a lot faster

Question 22

Artificial Selection: plants

Answer 22

• all from a single ancestral plant
• all of these are from a plant called brassica
• all derived from a single ancestral plant depending on which feature you are selecting for you end up with a variety of different brassicas
• plants with larger leafs- kale
• taste is not a big variation
• seeds all look similar
• humans choosing traits they want to see in the next generation overtime there are dramatic results

Question 23

Homology

Answer 23

• fundamental similarity due to descent from a common ancestor
  
  • anatomical- body parts different organisms have in common
  • developmental- patterns of embryonic development that might have
  • molecular- similarities in DNA sequences
• any similarities that different species might share because they inherited some feature from a common ancestor
  example: primates- features they all share (monkey, gorilla), they all have hands and same vision shared across groups of organisms

Question 24

anatomical homologies

Answer 24

• digestive system of vertebrates-whether turtle, dog or human digestive system is set up the same way
• we all have a mouth, esophagus, stomach, small intestine, large intestine and anus
• depending on what you eat there is modifications- gallbladder

Question 25

Anatomical Homology: Arms vs. Wing

Answer 25

-anatomical homology

• 4 limbs (arms) of humans, turtles, bats and whales
• on the outside they all look very different, all used for different things
• but underlying bone structure is exactly the same carpasi, metacarpals and phalanges (5 each)
• NS only works on whats there
• underlying bone structure that can then be modified with NS

Common ancestor is why they are all the same

Question 26

Anatomical Homologies: Vestigial Structures

Answer 26

• Human appendix
• “pelvic remnants” in whales (& some snakes)
• flightless birds’ wings
• VS- is body parts essentially that are the left overs of revolutionary path
• human appendix and muscles back of ears that are just there but not used
• ancestors used to use them
• appendix- useless, leftover, pouch by intestines. Some animals have these but they are really large called cecum- full of microbes that help break down plant material
• example: pelvic remnants/hip bones- whales- no use for the but they are there, left overs of evolution
• example: wings flightless birds- evolved from birds that used to fly and now they don’t. Ostreage - not man predictors over time these birds lose the ability to fly- they use wings for different things- display, cover faces but not for flying

Question 27

developmental homologies

Answer 27

• species have in common as early embryos
• we all start off the same as a single celled and fertilized egg, then 2 cells then 4 cells then 8 cells
• if you look at an embryo that is 8 cells big there is no way to know if you are looking at human or animal
• further in embryonic development you still can’t distinguish
• a lot of structures as human embryo that you lose as a fetus- tail is now gone, gill silts gone and yolk sac gone
• how do you start with one cell and make a human/turtle- now we have ideas of which genes are important

Question 28

molecular homologies

Answer 28

• genetic code identical in nearly all organisms
  
  • triplet of DNA bases –> specific amino acid
• homologous genes- from same ancestral gene
  
  • generally not identical
  • genes that are derived from the same ancestral genes, how many genes you have in common with another organism depends on how long you shared a common ancestor
• example: hemoglobin-genes that help make blood
  
  • hemoglobin- binds oxygen and carries oxygen throughout the bloodstream
  • mutations built up in genes over time which leads to divergence
• everybody uses DNA as instruction manual
• because we all do this- to make a protein you take 3 DNA bases and that translates into a amino acid- we use this info to determine how genetically similar or different species are

Question 29

molecular homologies: chart, molecular record

Answer 29

• looking at gene- ctyochrome oxidase gene- if you are an organism that needs oxygen then u need this gene. part of the electron transport chain and cellular respiration
• old gene and been around for a long time and shared for a lot of species
• tells u difference from species

-molecular record

Question 30

orthologs

Answer 30

-homologous genes in
separated species
- inherited from a common ancestor
- comparing homolegous genes in 2 different species

Question 31

paralogs

Answer 31

• homologous genes within a species
• homologous genes within a single species
• example: hemoglobin in blood made of 4 subunits 2 alpha and 2 beta they come together to fold into a hemoglobin- within genome we have alpha and beta hemoglobin gene. they are derived from the same hemoglobin gene with the same species

more detail on slide 29

Question 32

Natural Selection

Answer 32

individuals with heritable traits that make them better suited to their native environments tend to flourish and reproduce, whereas other individuals are less likely to survive
- ultimately results in a new species with a combination of multiple traits that are quite different from those of original species

Question 33

transitional form

Answer 33

in between fossils

Question 34

endemic

Answer 34

species found in one place of the world

Question 35

placental mammals

Answer 35

they are able to have a placenta during pregnancy

Question 36

homologous gene

Answer 36

• from same ancestral gene
• generally not identical
• how many genes you have in common with another organism depends on how long you shared a common ancestor