scroll to top
Stuck on your essay?
Get ideas from this essay and see how your work stacks up
Word Count: 1,457
191 On the Road To Speciation Species means kind as in a particular kind of duck Through the history of any species micro evolutionary processes have been introducing changes in the gene pools of its populations Remember particular alleles give rise to the heritable traits of populations As an outcome of mutation genetic drift gene flow and natural selection different alleles can increase or decrease in frequency or even disappear over time Given the variation in phenotypic details perhaps we should move past the details down to a more basic function that units members of a species and isolates them to all other species Reproduction as a defining function in species is central to the biological species concept Species are groups of interbreeding natural populations that are reproductively isolated from other such groups They belong to the same species because they can contribute to a shared gene pool 192 Reproductive Isolating Mechanisms Prezygotic Isolation a Certain isolating mechanisms take effect before or during fertilization Because they prevent mating or pollination between genetically divergent populations hybrid zygotes cannot form The same isolating mechanisms operate to prevent interbreeding of individuals of different species b Temporal Isolation Temporal isolation results from interpopulational differences in the timing of reproduction For most animals or plants mating or pollination is a seasonal event that is over rather quickly sometimes in less than a day Even closely related species may be isolated from each other if their reproductive cycles do no coincide The cicada a type of insect that spends nearly all of its life underground in immature form feeding on juices from plant tissues One species matures emerges and reproduces every 13 years The other species does this every 17 years Only once in 221 years do they release gametes at the same time c Behavioral Isolation This type of isolation is a major barrier to gene flow among related species in the same territory For example before male and
@Kibin is a lifesaver for my essay right now!!
- Sandra Slivka, student @ UC Berkeley
Wow, this is the best essay help I've ever received!
- Camvu Pham, student @ U of M
If I'd known about @Kibin in college, I would have gotten much more sleep
- Jen Soust, alumni @ UCLA