BIO 122

Question 1

What is gene flow?

Answer 1

Immigration/Emigration. Alleles move in/out of populations. The movement of alleles from one population to another.

Question 2

What’s mutation?

Answer 2

Random change in DNA that creates new allele

Question 3

What’s microevolution?

Answer 3

A change in allele frequencies within a population from one generation to the next

Question 4

What is speciation?

Answer 4

The evolution of two different species from an existing one-gorillas and chimpanzees are an example

Question 5

When are populations reproductively isolated?

Answer 5

When there is no mixing of genes between them

Question 6

What happens if 2 populations are reproductively isolated for several generations?

Answer 6

Genetic differences between them start to accumulate so that eventually the populations are genetically distinct enough to be unable to breed and produce fertile offspring

Question 7

Reproductive isolation of two populations is often caused by physical barriers

Answer 7

This form of isolation leads to allopatric speciation. What is allopatric speciation?
The formation of two species from an original one due to geographical isolation. Physical barriers include rivers, mountain rages, and deserts.

Question 8

Speciation can occur without a geographical barrier-this type of speciation is called sympatric speciation

Answer 8

Sympatric speciation is the formation of two species from an original one due to reproductive isolation whilst occupying the same geographical location

Question 9

What is reproductive isolation?

Answer 9

Biological barriers that prevent 2 species from interbreeding to produce viable, fertile offspring

Question 10

Prezygotic barriers prevent fertilization from even occuring-sperm cannot meet egg

Answer 10

Postzygotic barriers have fertilization occur but there is reduced survivability and/ or fitness of the hybrid zygote/offspring

Question 11

Prezygotic barriers include: Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation (reproductive organs dont fit together, lol), gametic isolation (sperm and egg dont mix)

Answer 11

Postzygotic barriers include: Hybrid inviability, hybrid infertility, hybrid breakdown

Question 12

What’s the morphological species concept?

Answer 12

Species are distinguished from each other by one or more distinct physical characteristics called diagnostic traits. Many of the morpological species Linnaeus defined have held up to 200 years of scrutiny.
Morphological species concept is useful for
paleontologists as a way to define fossil species based only on traits preserved in the fossil record but areof limited value

Question 13

What are some issues with morpological species concept?

Answer 13

Bacteria and other micro-organisms do not have many measurable traits, similarities and differences between organizms can be very subtle and sometimes misleading. Sometimes organisms look so similiar they appear to be the same species.

Question 14

What are cryptic species?

Answer 14

Species that look almost identical but are very different in other traits such as habitat use or courtship behaviors.

Question 15

What is the evolutionary species concept?

Answer 15

It relies on certain morpological traits to distinguish one species from another, it was proposed to explain speciation in the fossil record. It implies, nay requires, that the members of a species share a distinct evolutionary pathway. Small transitional changes in a trait are not used to define new species because these transitional forms are part of the same evolutionary pathway. However abrupt changes in traits indicate evolution of a new species in the fossil record. Species can be recognized individually by differences in diagnostic traits but collectively they share an evolutionary pathway distinct of other whale species.

Question 16

What’s the phylogenetic species concept?’

Pros: It does not rely on morphological traits to define a species. DNA analysis

Answer 16

It is used to identify species based on a common ancestor-a single ancestor for 2 or more different groups-and a species is the smallest set of interbreeding organisms that shares a common ancestor. In a phylogeny, a branch that contains all the descendantsof a common ancestor is said to be monophyletic.

Question 17

What’s the biological species concept?
Cannot be tested in nature because many potential species overlap in their distribution and thus dont have a chance to determine whether they are reproductively isolated. It cannot be applied to asexual reproducing living organisms or fossils.
Benefits: It confirms the lack of gene flow which is the best indicator that two populations are following independent evolutionary pathways

Answer 17

It relies primarily on reproductive isolation to identify different species. THe most important criterion, according to biological species concept, is reproductive isolation-physiological, behavioral, and genetic processes that inhibit interbreeding. If organisms cannot mate and produce offspring in mature or if their offspring are infertile, they are different species.

Question 18

What are some examples of sympatric speciation?

Answer 18

Well, divergence in diet, microhabitat, or both. Or polyploidy which is a chromosome number beyond the diploid number which is popular in plants. A polyploid plant can reproduce with itself but produces only sterile offspring when mated with diplodindividuals because not all of the chromosomes can pair up during meiosis

Question 19

What are the 2 types of polyploidy? Autoploidy and alloploidy

Answer 19

Autoploidy is when a diploid plant produces diploit gametes due to nondisjunction during meiosis. If this diploid gamete fuses with a haploid gamete, a triploid plant results which will be sterile and not produce offspring because the chromosomes cannot pair up during meiosis.
Humans have found a use for sterile plants because they produce fruits without seeds-if 2 diploid gametes fuse, the plant is a tetraplod, 4N, and plant is fertile as long as it reproduces with another ofits own kind. The huge strawberries of today are 8N plants
Alloploidy is when two different but related species of plants hybridize so the chromosomes double. 7 chromosomes from one plant cannot pair with 5 chromosomes from another plant. But IF the chromosome number doubles in the hybrid the chromosomes can pair during meiosis and result in fertile plant

Question 20

What is adaptive radiation

Answer 20

A type of speciation that occurs when a single ancestral species rapidly gives rise to a VARIETY of new species as each one adapts to a specific environment-like Darwin’s finches, cough cough. Instances of adaptive radiation include sympatric speciation following removal of a competitor, predator, or a change in the environment, when competition is reduced it results in ecological release.

Question 21

Ecological release is a chance for species to expand their use of resources within habitats that now have less competition. It provides a chance for new species to originate as populations become specialized to newly availible microhabitats. Allopatric speciation can also cause a population to undergo adaptive radiation

Answer 21

yeet

Question 22

What’s convergent evolution? When a biological trait evolves in two different unrelated species as a RESULT of EXPOSURE to SIMILIAR ENVIRONMENTS. Dolphins and tuna do not share a recent common ancestor but they both have a dorsal fin for swimming

Answer 22

Traits that evolve convergently in two unrelated lineages because of a response to a similiar lifestyle or habitat are said to be analogoius-such as the dorsal fins of dolphins and tuna. The opposite of analogous is homologous-traits that are similiar because they evolved from a common ancestor. Wings of butterflies are homologous to wings of moths.

Question 23

What’s gradualistic model of evolution versus punctuated equilibrium?

Answer 23

Gradualistic model=Darwin’s original theory of evolution that populations change gradually over time.
Small changes are passed from each generation onto the next( like horses have changed over 50 millions years) There are not a lot of transitional fossils-we have lots of big and small horses not a lot inbetween
Punctual model=Period of rapid change followed by period of stasis-not gradual change, supported by Eldredge and Gould who said that species appear suddenly, live for a period of time mostly unchanged and then become extinct. Most new species appear after mas extinctions