Answer:
a) Reinforcement - Selection for reproductive isolation by means of reduced fitness of hybrids.
b) Cryptic species - Species that are evolutionarily independent from each other, but ARE NOT distinguishable based on morphology.
c) Biological species concept - Distinguishing species based on whether or not they interbreed regularly with each other and are reproductively isolated from other such groups.
d) Morphospecies concept - Distinguishing species based on their phenotypes.
e) Species - The smallest evolutionarily independent unit.
f) Phylogenetic species concept - Distinguishing species by finding the smallest monophyletic group on a phylogeny.
Explanation:
Species is a group of organisms which are closely related and very similar to each other. It is the smallest evolutionarily independent unit that are able to interbreed and produce fertile offspring.
The inability of related species to breed due to behavioral, geographical, morphological or genetic differences is known as reproductive isolation. When two populations have come back into contact after being separated, the complete reproductive isolation between them results in speciation and the incomplete reproductive isolation causes the production of hybrids, which are of low fitness or sterile.
The process of speciation in which natural selection increases the reproductive isolation between two populations of species by acting against the production of hybrids of low fitness is known as reinforcement.
Cryptic species are the species which are evolutionarily independent from each other, but are morphologically indistinguishable and cannot interbreed.
The different species concept are; biological species concept, ecological species concept, morphospecies concept, phylogenetic species concept, evolutionary species concept etc.
Biological species concept is a concept of species in which the individuals of a group can interbreed and create fertile offspring, but cannot breed with other groups (reproductively isolated).
Morphospecies concept or morphological species concept distinguish species based on the differences in their phenotypes (morphological characters).
Phylogenetic species concept distinguish species by finding the smallest monophyletic group (group of all organisms that are the descendants of a common ancestor) on a phylogeny (evolutionary history of genetically related group of organisms or species). This group have a shared and unique evolutionary history because they are descended from a common ancestor.
