species & speciation

Question 1

what does the criteria to define species include? (species concept)

Answer 1

morphological, biological, phylogenetic

Question 2

what is the morphological species concept? and a limitation?

Answer 2

visible anatomical characteristics. species can very in size and colouration

Question 3

what is the biological species concept? and a limitation?

Answer 3

reproductive isolation & genetic distinction. doesn’t apply to asexually reproducing species and can’t be used for extinct species

Question 4

what is the phylogenetic species concept? and a limitation?

Answer 4

evolutionary history aka tree of life. not enough information and cant see which species are able to breed (gene pool)

Question 5

what are ring species?

Answer 5

some plant/animal species have a ring shaped distribution that surrounds inhabitable territory. they may have variation depending on their area

Question 6

what is clinal variation?

Answer 6

when species distributed over large, environmentally diverse area, some traits may exhibit a CLINE, a smooth patter of variation across a geographical gradient

Question 7

what are the two types of isolating mechanism? and when do they occur?

Answer 7

prezygotic: prevents production of hybrid offspring before mating, postzygotic: prevents production after mating

Question 8

what are the models of speciation?

Answer 8

allopatric & sympatric

Question 9

when does allopatric speciation occur?

Answer 9

may take place when there’s separation

Question 10

what is sympatric speciation?

Answer 10

reproductive isolation evolves between distinct supgroups (races) that arise within one population. this doesnt require separation

Question 11

what is secondary contact?

Answer 11

contact after geographical isolation. provides test if genes have diverged enough for reproductive isolation. may resume interbreeding

Question 12

what is reinforcement?

Answer 12

when prezygotic mechanisms reinforce postzygotic barriers

Question 13

what is genetic divergence in relation to speciation?

Answer 13

allopatric. without geneflow, geographically separated populations accumulate genetic differences thru mutations, genetic drift, & natural selection

Question 14

what is polyploidy in relation to speciation?

Answer 14

sympatric. generally results in instant speciation - may be reproductively isolated from parents. provides new genetic material for evolution

Question 15

what is chromosome alterations in relation to speciation?

Answer 15

may foster postzygotic isolation from chromosomal differences (inversions, translocations, deletions, & duplications)

Question 16

why is there no universal concept of of species that applies to all organisms?

Answer 16

we have different rules for different groups of organisms. species are defines with multiple lines of evidence (multiple species concept)

Question 17

advantage and disadvantage to the species concept: phylogenetic

Answer 17

can be applied to all organism ONLY if data collected. data cant be taken from fossils but can from preserved remains, for example a mammoth frozen in permafrost/amber

Question 18

advantage and disadvantage to the species concept: morphological

Answer 18

can compare traits with fossils. difficult to distinguish species that look similar. phenotypic variability is not consistent for different species. no info on how they evolved

Question 19

advantage and disadvantage to the species concept: biological

Answer 19

geneflow within species, cohesive traits. explains how species evolves and is testable. doesnt work with asexually reproducing organisms and reproductive behaviour cant be determined for extinct species.

Question 20

what are the prezyogtic isolating mechanisms?

Answer 20

ecological, behavioural, temporal, mechanical, gametic

Question 21

what is the isolating mechanism: ecological?

Answer 21

occupy same region but live in different habitats

Question 22

what is the isolating mechanism: behavioural?

Answer 22

signals not recognized by another

Question 23

what is the isolating mechanism: temporal?

Answer 23

mate at diff times

Question 24

what is the isolating mechanism: mechanical?

Answer 24

differences in structures prevent interbreeding

Question 25

what is the isolating mechanism: gametic?

Answer 25

gametes not compatible, can not fertilize

Question 26

what is the hybrid zone?

Answer 26

where individuals of previously separated populations interbreed. hybrids are often not adapted to areas outside of hyrbid zone.

Question 27

what does reinforcement and isolation do in relation to hybrids?

Answer 27

reinforcement accelerated isolation after secondary contact. if postzygotic isolation occurs, hybrids tend to have lower fitness

Question 28

what are traits involved in reproductive isolation?

Answer 28

anything that makes a difference in reproduction between individuals: structures, hormones, sperm recognition proteins, accessing recourses, behavioural differences

Question 29

advantage and disadvantage to the species concept: ecological/environment

Answer 29

it explains the role of environment in speciation. but it is unable to explain existence of same species who live in different environments e.g. tadpoles and frogs

Question 30

what are the post-zygotic isolating mechanisms?

Answer 30

hybrid inviability, hybrid sterility, hybrid breakdown

Question 31

what is the isolating mechanism: hybrid inviability?

Answer 31

Would have 2 sets of distinct genes/developmental instructions that are too different to allow development.. But the offspring would die young

Question 32

what is the isolating mechanism: hybrid sterility?

Answer 32

Can grow up but become unable to produce functional gametes.

Question 33

what is the isolating mechanism: hybrid breakdown?

Answer 33

Can develop and also mate with other hybrids, and both parent species. However, second generation will have higher fatality, lower fertility. Long-term reproductive isolation rather than immediate.

Question 34

Why is sympatric speciation more common in plants? Is polyploidy a possible mechanism of sympatric speciation for animals?

Answer 34

to undergo polyploidy, need to fertilize another gamete with twice the normal amount of genetic material. plants are able to self-fertilize and perpetuate this for multiple generations, whereas animals lack this ability.

Question 35

Would it be considered speciation if the Northernmost bird population was unable to breed with the Southernmost bird population for clinal variation?

Answer 35

No. Because there is gene flow through intermediate populations, that would not be considered speciation, even if the two populations were unable to breed.

Question 36

Two identical petri-dishes of Saccharomyces cerevisiae, also known as budding yeast, were grown in either Condition A or Condition B. After 100 generations (15 hours), yeast from both conditions were placed in the same petri dish and were grown together. If the two populations of yeast were unable to interbreed, did speciation occur?

Answer 36

Technically, speciation DID occur if you were looking at it through the biological species concept. However, in real life it would depend on the scientific governing body. We’re very familiar with the case of larger organisms experiencing allopatric speciation over large time scales. But allopatric speciation can occur over short time scales as well.