User:PolarBear3721/sandbox

Mating
All stickleback species show similar, unusual mating behaviour. The males develop a red breast and construct a nest from weeds held together by secretions from their kidneys, then attract females to the nest. A female lays her eggs inside the nest, where the male fertilizes them. The male then guards the eggs until they hatch, and may continue to guard the fry after they hatch. This large investment in both the nesting site and guarding of the eggs limits the number of females a male can mate with. This introduces the ability for selection to favor male mate choice. Some males die following spawning.

Mating Choice
Typically, the sex with the greatest parental investment has the strongest mate preferences. Stickleback species have been observed to exhibit mutual mate choice in which both the male and female have strong mate preferences. This is due in part to the strong parental investment on behalf of the male in guarding the eggs.

Female mate choice
Female sticklebacks show a strong preference to male stickleback with bright red coloration under their throats. Females mate both more often with males with brighter red coloration and give on average, larger eggs to be fertilized by these males. This preference has led to brighter red coloring overtime. This association is possible because the red coloration can only be produced by males that are free of parasites. This is referred to in the Hamilton-Zuk hypothesis.

Female mate choice has also been seen to be condition dependent. Females are almost always the more choosy sex in most species. Female sticklebacks though, have been found to be less choosy of mates when in poor physical condition and inversely, more choosy in good condition.

Male mate choice
The large investment in both nesting site and guarding of eggs by males limits the number of females a male can mate with. This introduces the ability for selection to favor male mate choice. Male mate choice is rarely studied or observed in many species but multiple studies have confirmed male mate choice within stickleback species. Males show a choosiness similar to females as to what female they are willing to court and mate. In some species, such as the three-spined stickleback, this choosiness is due to the increased parental investment of males by spending time and resources guarding the fertilized eggs. Male sticklebacks have been observed to show preference towards female sticklebacks that are larger both in overall size and also in total length. This is believed to be because larger females on average produce larger eggs, which leads to a greater offspring survival and fitness. In addition, male sticklebacks have also been observed to prefer females with more distended or bloated stomachs. The benefits of this is also due to larger eggs and thus offspring survival and fitness