Final answer:
Environmental conditions are the key factor influencing a species' life history strategy, leading to either fast or slow life history traits. Such traits, which evolve through natural selection, include reproductive timing and parental investment, and are adapted to maximize survival and reproductive success within their environment.
Step-by-step explanation:
The environmental conditions are the primary influencing factor that determines whether a species develops a fast or slow life history strategy. In scenarios where dramatic environmental changes occur, such as a significant drop in water level, a species may rapidly adapt to new conditions, leading to a swift change in speciation rates. For example, a small population of snails, finding itself in a new environment due to such a change, may undergo rapid evolution due to a restricted gene pool and intense selection pressure. Variations that better suit the new environment can spread quickly through the population and become dominant.
In addition to environmental triggers, life history characteristics such as amount of parental care, age at first reproduction, and number of offspring evolve over time through natural selection. These traits inform whether a species will adopt a strategy that favors quick reproduction with less investment per offspring (r-selection) or a strategy that leans towards a larger investment in fewer offspring with delayed reproduction (K-selection).
Species across the spectrum exhibit a variety of strategies, which is a result of adaptations to their unique environments and resource availability. These life history traits are critical for understanding a species' survival and reproductive success in their ecological niche.