Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Many definitions of species have been offered, but none of them proved to be satisfactory. The definitions did not categorically provide the basis to decide whether two similar groups are distinct species or only sub-species. Again what is the criterion to decide the distinctness of a species? Some tried to specify the degree of difference that would distinguish a species from another. Apart from the difficulty in quantifying such differences, there are also other problems. Certain forms which show very little morphological differences proved to be very distinct species. In other cases, such as Homo sapiens, undoubtedly a single species, different races have pronounced differences. The discontinuity between groups, it appears, depends less on the degree of differences and more on the constancy of differences. Another approach to define species was to distinguish related organisms on their inability to breed. Many definitions of species have relied upon such interspecific sterility and sterility of offsprings, that is hybrid sterility. This proposition also has certain inherent problems. It is not easy to identify cases in which organisms do not interbreed, and those which can breed, but do not do so for certain reasons. At these times, sterility cannot be deemed to be an appiopriatc criterion for defining species. Nevertheless, reproductive isolation or inability to breed has been the commdn element in the definition of species provided by many evolutionary biologists, be it Dobzhansky, Goldschmidt or Ernst Mayr. Reproductive isolation, the discussion of which follows later in this unit, has been the basis for defining the species and speciation.' Such an isolating mechanism becomes a barrier for the flow of genes between related populations and the concept of biological species centres around this phenomenon.
What is the relationship among environmental resistance and the population growth according to the biotic potential curve and the real population growth curve? The difference
Q. How to calculate Hydrogen Ion Concentration? Ans. The hydrogen ion concentration has a significant role to play in growth of bacteria as every microorganism has a minim
how does respiration takes place in animals ?
Define ascending type of paper chromatography? The ascending type consists in dipping the lower end of the paper containing the sample spots into the solvent so that it is abov
Explain Matching energy intake to energy expenditure? To be in energy balance, an athlete needs to consume about the same number of calories that he or she expends on a daily
Q. What are the Symptoms of gastritis? Anorexia, epigastric discomfort, heartburn and severe vomiting, pain in upper abdomen, Headache and even bleeding.
Explain about the Microbiological Study of Water? Water is the basic need of life. River, streams and underground water is the prime source for water. However, disposal of indu
Q. Issues to be discussed while counselling a diabetic patient ? Issues to be discussed · Counselling at Diagnosis · Diabetes is Controllable · Counselling for Day
What is Mefloquine Mefloquine is taken once weekly, but recent reports of serious psychiatric adverse effects have prompted the manufacturer, along with the FDA, to strengthen
Write about embryonic stem cell invitro methord in which transgenic animal were generated and efficient show how homologous recombination happening?
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +1-415-670-9521
Phone: +1-415-670-9521
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd