In some large groups of plants, including dandelions, oaks, and willows, the biological species concept is complicated because the process of _ allows gene flow to occur between good _ that can be easily distinguished based on appearance. Group of answer choices allopatric speciation; ring species sympatric speciation; ring species hybridization; ecological species hybridization; morphospecies

Hybridization can be defined as the process by which individuals belonging to two different variants or species are capable to mating with each other and producing viable offspring having characteristics of both the variants or species. This process is common in plants in which cross-fertilization is commonly used as the procedure for reproduction.
Morphospecies can be defined as an older concept which was used to determine the difference among various species by analyzing the variation in the morphology of different species.
Allopatric speciation can be defined as the phenomenon due to which individuals belonging to the same species get separated into a number of sub-populations due to the development of a geographical barrier in between them. The resulting sub-population of individuals develop mutations, in order to adapt themselves to the particular environment each sub-population is exposed to, independent of each other, and during the course of evolution they develop into new species.
Sympatric speciation can be defined as the phenomenon by which some individuals belonging to a particular species develop certain mutations that provide them better adaptive capability to their environment. During the course of evolution, these individuals develop into a new species. Here, both the parental species and the new species inhabit the same geographical area.
Ecological Species can be defined as a species concept in which the organisms which occupy a particular habitat and utilize a particular set of resources within its habitat, which is called the niche, form a species.
Ring Species can be defined as the sub-populations of a particular species that inhabit a habitat in the form of a ring such that a geographical barrier is present at the center of the ring. Here, the sub-populations which are present adjacent to each other are capable of inter-breeding with each other but with evolution the species who occupy the two terminus of the ring develop characteristics that causes them to develop into two new species which are incapable of interbreeding with each other.