In brood parasitism as observed in Asian koel and Indian crow,the eggs of . . . . . . .

. . . . . . $A$ . . . . . . is a potent force in organic evolution. Identify the $A$.

Study the four statements $(i-iv)$ given below and select the two correct ones out of them.
$(i)$ $A$ lion eating a deer and a sparrow feeding on grains are ecologically similar in being consumers.
$(ii)$ Predator star fish $Pisaster$ helps in maintaining species diversity of some invertebrates.
$(iii)$ Predators ultimately lead to the extinction of prey species.
$(iv)$ Production of chemicals such as nicotine,strychnine by the plants are metabolic disorders.
The two correct statements are

Discuss the various types of positive interactions between species.

Why is water hyacinth called the 'Terror of Bengal'?

$A$: Five closely related species of warblers living on the same tree can avoid competition and co-exist.
$R$: This occurs due to behavioural differences in their foraging activities.