Origin of different types of beaks occur due to
Natural selection
Interspecific competition
Genetic drift
Interspecific variation
When we say ''survival of the fittest'', does it mean that $(a)$ those which are fit only survive, or $(b)$ those that survive are called fit ? Comment.
How Biological evolution has taken place ?
Theory of natural selection was given by
Explain theory of inheritance of acquired characters with proper example.