Final answer:
Speciation is the gradual accumulation of favorable traits in a population over time, leading to the formation of new species. This can happen through gene mutations or gene flow, with natural selection playing a key role in the spread of advantageous traits. Evolution is not goal-directed but is a response to environmental pressures.
Step-by-step explanation:
The slow accumulation of favorable traits over time that results in the formation of new, distinctive species is known as speciation. New traits can arise through mechanisms such as gene mutations or gene flow, and for these traits to become predominant in a population, they must provide some sort of advantage through either natural or sexual selection. Over time, these adaptations can lead to the development of new species as they become increasingly distinct from their ancestors.
Speciation can occur in a gradual manner, where species diverge at a slow and steady pace as traits change incrementally, a concept known as gradual speciation. Alternatively, punctuated equilibrium is a model where species diverge quickly and then remain unchanged for long periods of time. This is in contrast to the idea that evolution is constantly proceeding at the same slow rate.
It is essential to note that evolution is not goal-directed; it does not aim to produce 'better' or more complex organisms over time. Rather, it is a response to the current environment, enabling organisms to maximize their reproductive success under prevailing conditions. Environmental pressures and genetic variables can lead to speciation, involving processes like allopatric and sympatric speciation, as well as adaptive radiation.