List all the sexual selection models which are prevailing in nature with examples?

Sexual selection models describe the evolutionary processes and mechanisms that shape the mating behaviour, mate choice, and reproductive success of individuals within a population. Several prevailing sexual selection models have been proposed to explain the diversity of mating strategies and traits observed in nature.

 

Bateman's Principle:

 

Proposed by: Angus Bateman

Description: Bateman's principle suggests that the variance in reproductive success is typically higher in males than in females due to differences in the investment of gametes and parental care between sexes.

Example: In many species of insects, such as fruit flies (Drosophila spp.), males typically invest less in parental care and can mate with multiple females, leading to greater variance in male reproductive success compared to females.

 

Parental Investment Theory:

 

Proposed by: Robert Trivers

Description: Parental investment theory posits that the sex that invests more in offspring (usually females) will be more selective in choosing mates, while the other sex (usually males) will compete for access to mates.

Example: In birds, female peafowl (peahens) invest significantly in the production and care of eggs and offspring, leading to strong mate choice and selection for elaborate male peacock displays, which serve as indicators of genetic quality and parental investment.

 

Runaway Selection:

 

Proposed by: Ronald Fisher

Description: Runaway selection occurs when a preference for a particular trait (e.g., exaggerated male ornaments) becomes genetically linked with the trait itself, leading to the rapid evolution of elaborate traits through positive feedback.

Example: The long tail feathers of male widowbirds (Euplectes spp.) are believed to have evolved through runaway sexual selection. Females prefer males with longer tails, leading to the rapid evolution of increasingly elongated tail feathers in males over successive generations.

 

Handicap Principle:

 

Proposed by: Amotz Zahavi

Description: The handicap principle suggests that elaborate secondary sexual traits serve as honest indicators of genetic fitness because they are costly to produce or maintain and therefore only high-quality individuals can afford them.

Example: The antlers of male deer (e.g., red deer, Cervus elaphus) are energetically costly to grow and maintain and are used in aggressive displays during mating season. Antler size and complexity serve as honest indicators of male genetic quality and dominance.

 

Sensory Bias:

 

Proposed by: Ryan & Rand

Description: Sensory bias occurs when a pre-existing sensory bias in females (or males) predisposes them to prefer certain traits or behaviors, leading to the evolution of exaggerated traits in the opposite sex.

Example: Female guppies (Poecilia reticulata) exhibit a preference for males with brightly colored spots, which resemble the coloration of their preferred food sources. This preference has led to the evolution of elaborate male coloration through sensory bias.

 

These are just a few examples of prevailing sexual selection models in nature, each offering insights into the evolutionary processes underlying mating behavior, mate choice, and the evolution of secondary sexual traits across diverse species.