Final answer:
Organisms are motivated to reproduce by the drive for genetic information survival. This is influenced by both proximate causes like pleasure-seeking behavior and ultimate causes such as the long-term transmission of genes. Natural selection plays a key role by favoring traits and behaviors that increase an organism's fitness.
Step-by-step explanation:
The biological factor that motivates organisms to reproduce is primarily the drive for genetic information survival. To understand this from both proximate and ultimate causes, we look at the behavior and strategies that contribute to successful reproduction. Proximate causes like pleasure-seeking behavior and complex reproductive strategies can be immediate factors, while ultimate causes focus on the long-term success of passing on genes to future generations.
Reproductive strategies vary and can often be predicted based on nutritional requirements and habitat. Behaviors that increase an organism's fitness, such as obtaining resources and caring for young, are favored by natural selection and therefore more likely to be the ones that are passed down to the next generation.
In evolutionary biology and sociobiology, the motivation for reproduction is not just to continue the species, but to pass on the chromosomal patterns that give the species a survival advantage. This is evident in various characteristics and behaviors, including altruistic behaviors that appear to help ensure the survival of related individuals, or the adaptations such as better running speed, that increase an individual's fitness.