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mutations and genetic recombination in sexually reproducing organisms are major sources of variations in natural populations in this section we will
in the preceding section we emphasised the fact that cvolution or the continuous adaptations to the environment can take place only when pheiiotypes
natural selection can therefore mean differential reproduction among members of the sarne gene pool we earlier said that selection would promote
assuming that variability of populations were non-genetic that is not controlled by genetic material once again chance events alone would determine
variability refers to the differences in heritable traits exhibited by the individuals of a species one of the major contributions of darwin to the
organisms are made to compete for their needs from the environment the competition as we pointed earlier could be for the food and territory to
by prodigality of nature it is meant that organisms have an enormous potential to reproduce a carp or salmon is known to lay over a million eggs a
darwin put fort the notion of the survival of the fittest how do we define fittest the answer usually given is those who survive so you can readily
in that unit you also learnt about darwin who based on his extensive observations and interpretations showed that evolution is a simple fact of
the effect of natural selection on colonies or population favouring one group in preference to other may be referred to as group selection a group
before we proceed to discuss kin selection we should define the term altruism it refers to the behaviour pattern of an individual in the population
while explaining the concept of natural selection we have stressed the fact that natural selection is synonymous with differential or non-random
in this section you will be introduced to a variant of darwinian concept of natural selection which he termed sexual selection you may have observed
tonicity and the plant cell table 3 amount of water displaced by potato samples before and after
coevolutionary relationships between parasites and their hosts can be more complicated than between predators and their prey as in the case of
there has been a perfect coevolution between plants and herbivorous animals this has often developed into a mutually beneficial relationship whereas
predation is a process by which one organism predator eats another organism prey if the prey population is abundant the predator population also
you now know that natural seleqtion aims at evolving adaptations of organisms in response to environmental changes in the inanimate world also many
consider two species of organisms species a and species b species a has a population in a community another population species b arrives into the
from your studies in ecology you must be aware that most ecosystems are quite complex consisting of several habitats and that habitats in turn are
in the preceding block you learnt the darwinian premise of natural selection based on certain facts and deductions thereof you would have noticed
darwin while evolving the concept of natural selection laid emphasis on competition among individuals belonging to a species that is intraspecific
in this section we shall discuss a classic example of natulal selection in action in the preceding unit it was stated that natural selection always
it is generally believed that genetic drift occurs as a result of sampling error as we said earlier it occurs in small populations such as peripheral
hybrid sterility can be regarded as yet another form of interspecific sterility the offspring of the interspecific crosses are mainly sterile