In sexually reproducing populations, only half, the females, reproduce (this does not mean that the males are not involved, but it is the females that generally deal with the fertilized egg). Additionally, sexual mating habits are very complex. There is competition for mates; there can be issues with the viability of sex organs and sex cells. Fertilization and embryonic development are very complex and lengthy compared to asexual reproduction. But even with all of this, biologists do not consider asexual reproduction more efficient than sexual reproduction. It is simply noted that there are more "costs" to sexual reproduction than asexual reproduction. Sexual reproduction is more involved and therefore has higher related costs. Asexual reproduction would be considered less expensive.