Speciation

What is speciation? Browse through speciation, causes of speciation, reproductive isolation, evidence of speciation, and cospeciation BEFORE answering the questions below. There will also be a communication mark given to this assignment in the final comments regarding how well you use RASE to develop open response answers. What is a species? Organisms that can interbreed in the wild and produce fertile offspring Organisms that can't interbreed in the wild but produce fertile offspring Organisms that can interbreed in the wild and produce infertile offspring Organisms that can interbreed in the captivity and produce fertile offspring What is speciation? Production of gametes in the wild Production of new species Production of hybrids Production of new organisms When has speciation occurred? When populations no longer look the same When populations no longer have the same frequency of alleles When populations can no longer interbreed When populations are living in different environments A horse and a donkey can successfully mate to produce offspring known as a mule. Mules are sterile . Would mules be classified as a species? Yes, mules have enough of their own traits to be considered a species. Yes, the fact that have different number of chromosomes makes them a different species No, mules are too similar to the parent species No, due to their inability to reproduce successfully. The disappearance of a species refers to evolution migration extinction mutation Why is a zonkey infertile? What 3 things do they point out toward the end of the video? Explain Define allopatric and sympatric speciation. What is the difference between allopatric and sympatric speciation? Sort the following examples into allopatric speciation and sympatric speciation Allopatric Speciation River forms after an earthquake Lava flow from a volcano separates one side of a mountain from another. A road is build through a swamp area Rising and falling tides. Continental drift Mountain Range rising Population migration. Sympatric Speciation Polyploidy in plants- DNA sets duplicated in a generation. African Cichlid fish in the same pond do not mate with one another. Orchids in the same field are unable to pollinate one another. Transient vs resident Orcas- They live in the same area at times but choose not to interbreed. What are prezygotic and postzygotic isolation mechanisms? Read the following to gain an understanding of the difference. Reproductive isolation is a mechanism that keeps species from mating with others. Prezygotic isolation prevents the fertilization of eggs while postzygotic isolation prevents the formation of fertile offspring. Prezygotic mechanisms include habitat isolation, mating seasons, "mechanical" isolation, gamete isolation and behavioral isolation. Postzygotic mechanisms include hybrid inviability, hybrid sterility and hybrid "breakdown."Prezygotic Isolationa. Habitat isolation- 2 species live in separate habits then they will never be able to get together to mate. Ex- African and Asian elephants, lions and tigers.b. Temporal isolation seasons- if the time of year that a species prefers to mate is different than the time another will mate they will not mate. Ex- flowers that release pollen in the morning vs. flowers that release pollen in the evening.c. Behavioural Isolation- one species does not like the courtship rituals of another. Different birds sing different songs, some animals are combative, bird dances, colouration etc.d. Mechanical Isolation- this occurs when the reproductive organs of the male and female organisms attempting to mate do not "fit." Ex male great dane and a female Chihuahuae. Gametic Isolation-sperm and egg are not compatible because of chromosome number, receptor protein incompatibility, pH, wrong enzymes etc.a,b,c are all prezygotic isolating mechanisms that prevent mating from ever happening.d,e are prezygotic isolating mechanisms that prevent the fertilizationof the egg by the sperm.Postzygotic Isolating Mechanismsa. Zygotic Mortality-A type of incompatibility that is found as often in plants as in animals occurs when the egg or ovule is fertilized but the zygote does not develop, or it develops and the resulting individual has a reduced viabilityb. Hybrid Inviability- is a barrier which reduces a hybrid's capacity to mature into a healthy, fit adult. The relatively low health of these hybrids relative to pure-breed individuals prevents gene flow between species. They are born but can't mate or produce offspring that die early.c. Hybrid Infertility- Among those hybrid offspring that do develop normally and reach sexual maturity, most are sterile, meaning they do not produce viable gametes. For example, mules result from the mating of a horse with a donkey. Can you see the difference? Sort the following examples into either prezygotic and postzygotic isolating mechanisms. Prezygotic Isolation Frogs live in the same pond but one mates in early spring and the other in late spring. Lions and tigers can interbreed but live in different habits and don't normally cross paths. Loons do not respond to the mating calls of mallards. St. Bernards are not capable of mating with toy poodles Postzygotic Isolation Some types of frogs mate but produce tadpoles that die before they become frogs. Horses and donkeys mate to produce sterile mules. The offspring of hybrid copepods have less potential for survival or reproduction. What evidence exists for speciation? Be descriptive and include examples. Explain cospeciation. Include diagrams, pictures, and examples in your explanation. Sort the following statements to determine which are examples of geographic isolationvs.reproductive isolation. Geographic Isolation separation of two populations by a physical barrier Examples: mountains, rivers, volcanoes Example: Galapagos finches! different islands, ultimately different species Reproductive Isolation caused by behavioral and temporal barriers Examples: differences in the mating season found in the toad species Bufo americanus and Bufo fowleri. Example: eastern and western meadowlarks will not mate with each other because they use different songs to attract mates.