Reduction of gene flow. However, speciation might also happen in a population with no specific extrinsic barrier to gene flow. Imagine a situation in which a population extends over a broad geographic range, and mating throughout the population is not random.
The Internal Revenue Service places restrictions on how far back you can amend your tax return, regardless of whether you owed tax or received a refund. Filers must use Form 1040X to amend a return and should only file an amendment to report certain changes. You have three years from the due date of the original return or two years from when you paid tax owing to submit an amended return. A pen next to an income tax form.
If you forego the carryback period, you can still only carryover the loss for 20 years into the future. Because the IRS assumes that most people will want the speedy refund a carryback can provide, you must attach a statement to your tax return for the NOL year, or to an amended return for that year filed within six months of its due date excluding extensions.