Pseudomyrmex ants live exclusively in the swollen thorns of acacia trees. In return for food and shelter provided by the trees, the ants aggressively defend the tree from leaf-eating insects. This interaction between ants and acacias represents an example of

#Question id: 9573

#Section 1: Ecology

#Question id: 11173

#Section 2: Evolution

Chemical signals between individuals of the same species are called

#Question id: 10827

#Section 2: Evolution

A barnacle grows on a whale, doing it no harm. This is an example of

#Question id: 11263

#Section 4: Behavioural Ecology

Studies of parasitism of kentucky warblers by brown-headed cowbirds have shown that fragmentation has ____________the rate of parasitism because of ____________ edge habitat and ____________ habitat quality.

#Question id: 4643

#Section 2: Evolution

The treeʹs horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V—Z) represent various common ancestors. Letʹs say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

How many separate species, both extant and extinct, are depicted in this tree?