one of the phenotypes disappeared so something could have happened to make that group disappearBIOLOGY 152 1st Edition Lecture 24Outline of Last LectureI. Bottleneck Effect J. Founder Effect II. Speciation a. What is a Species? Outline of Current Lectureb. Biological Species Concept c. Problems with thisDefinition III. Forces of Speciation a. Pre-Zygotic b. Post-Zygotic c. Adaptive Radiation IV. Phylogenetic RelationshipsCurrent LectureSpeciation IIBiological Species Concept continuedProblems with this definitionAre currently organisms that have problem with speciation — asexual species- plant that only exist as a male not a female in North America butit is an invasive species - so this plant is obviously doing fine - hemlocks being killed in New England — they can’t breed unlessthere is a specific Japanese spruce nearby (part of their life cycle) - females lay female eggs (clones) - hybridization (especially in plants) These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- many distinct species can create fertile offspring — so is this a separatespecies? Forces of Speciation- Sympatric vs. allopatric**Clicker Question**Data drawn from the wild on fruit flies. What mates did south facing slope females choose (left graph)? What mates did south facing males choose (right graph)? Wanted to know what side each chose.- both NFS and SFS prefer mates from their side of origin - reproductive isolation starting from birth — they’re 300 meters apart but they're associating differently (speciation in process possibly even though at the moment they look the same and live in the same type of area) Allopatric = separated geographically (won’t cross, have no contact with each other) Sympatric = not separated geographically**Clicker Question**Hawaiian Fruit Flies separated into two populations, one were raised on maltose based food and the other was raised on starch based food. Then put them back together and the ones raised on maltose are more likely to mate with other maltose raised flies and same for starch flies. She has created allopatry (seperated, not interbreeding between the two groups). So what would have to be done to alter the results so that there would be no mating preference?- Take two flies from the maltose & put them in with starch flies everygeneration - why would this work? the two groups are mixing — you have gene flow between the two populations, alleles are moving from maltose to starch making the difference smaller - there is a behavioral difference happening Gene flow works against speciation. Reproductive isolation can be pre-zygotic or post-zygoticPre-zygotic:Mechanical = parts don’t fit together, organisms are physically incapable of exchanging DNATemporal = for some reason they mate at different timeex: two frog species, the top one mates from Jan-March, other fromMarch-May so they don’t mate but if you tricked them into mating inthe lab they have the potential for having fertile offspringGeographical = species in different places (sri lankan elephant and asian elephant) Behavioral = live in the same place but they don’t mate becauseof behaviorex: bower birds — male build elaborate nest to attract female, blue bower bird uses blue things to attract, red bower bird uses red thingsso they live in the same- with fireflies, blinking is species specific & females blink to attract amale so they don’t understand the other species mating behavior(looking for a specific blinking pattern)**Clicker Questions**How would gene flow between 2 allopatric populations affect the chance of speciation? It would likely decrease the chance of speciation — gene flow fights against speciationRock Mountain juniper and one-seeded juniper have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on females ovules of the other species, then which of these terms is applicable?- MechanicalWhen hybrids formed in a hybrid zone (like where the southern salamanders meet) can breed with themselves and both parent species ad they have equal fitness to the parent species, one would predict that:- Reproductive barriers would lessen and the two parent species would fusePost-zygotic:sterile hybrids = offspring of two different species that cannot produce offspring of their ownex: Ligers Speciation: Sympatric- still a reproductive barrier so sexual selection ,habitat, ploidy - much rare — hawthorne maggot fly, when apples came in disruptiveselection led to a new species Adaptive Radiation- when a founder (single species) comes into a new place and thendevelops into several different species - common example = small group of finches showing up on galapagos islands and radiaes out to utilize different resources and you eventually get different species of finches - ex: honeycreepers on Hawaii - allelic diversity was limited in this group to begin with but overmillions of years you have mutation so you can get selection **Clicker Question**Researching a species of loud jungle fowl. 30 years ago there were redand gray males. Now all of the birds are red. Why might this be the case?- population bottleneck could be the case if you had some sort of eventhappen that got rid of most of the gray males one of the phenotypes disappeared so something could have happened to make that group disappear- could also be positive selection technically - stabilizing and disruptive selection — you need to have a gradient oftraits, but in this cause you only have red and gray, not bright red tograyish Phylogenetic relationshipsI. PartsII. InterpretationsIII. Morphological vs. molecularPhylogenetic Trees- proposed evolutionary relationship based on morphological or geneticdata coming together to show a conclusion - nodes = shows a (hypothesized) common ancestor - taxa = at the ends of the tree (shows that two taxa coming from the same node share a common ancestor). They don’t necessarily mean species, it could be “primates” or “animals” - monophyletic group = all of the descendants and the ancestors — doesn’texclude a descendent or an ancestor (but doesn’t have to be the wholetree) - defined by a shared derived trait = synapomorphy Synapomorphies arise