How do vertebrates reproduce?

Answer 1

It depends on the animal! Some reproduce by laying eggs, others by live birth.

Answer 2

Mostly with sex just like us really ;) There is an all-female lizard species using cloning techniques though.

Fish, amphibians, reptiles and birds lay eggs, though some sharks have their eggs hatch inside their bodies and give birth to live young. Mammals, of course, always do so except for the platypus and echidna, which still lay eggs.

usually by sexual reproduction. asexual is for less complex organisms.

Well, as I said in my original answer, the lizard species cloning itself (giving birth to female clones of themselves) is reproducing asexually (parthenogenesis). They evolved from a sexual species with males, though. Sexual or asexual reproduction has nothing to do with the complexity of the organism; it can arise in any species, theoretically. ^^