WHAT IS A SPECIES?
Scientists can’t always agree on the definition of what a “species” is, let alone decide whether a given animal is new to science. There are over twodozen proposed “species concepts” of how to define a species. It may seem rather cut and dry to distinguish a species, but when you think about it, it’s not so simple after all. If two individuals are different colours should they be classed as different species? Should occasionally interbreeding animals be classes as a species even if they look very different?
Here are a few of the most widely accepted species concepts: • Biological Species Concept –
This is the most palatable of the concepts. It is based around a species being classed as a group of interbreeding individuals that produce fertile offspring. • Morphological Species Concept – Recognition of a species is based on morphological similarity in appearance between a group of individuals.
• Genetic Species Concept – Much like the Morphological Species Concept, although a species is defined by its genetics and genetically similar groups are considered a species
The fairy and flasher wrasses have caused great confusion when new species are being named. As these images illustrate, hybrid flashers are common; however, if they are creating fertile hybrids, are they really distinct species?
On the other hand, I recently saw a small fairy wrasse in the Solomon Islands that has just been given its own name. In 2015, Marinda’s fairy wrasse was split from the redback fairy wrasse that shares the same geographic range across the whole northern coast of New Guinea. They are superficially similar in appearance, but Marinda’s is smaller and has a different shaped dorsal fin (see pictures on following page). They were finally considered to be distinct, although it was discovered that they are genetically almost identical. It becomes very hard to know where to draw the line when Nature continues to throw curve balls such as this.
TOP LEFT Paine’s flasher wrasse was one of several new flasher species to be named in 2016 (Paracheleinus paineorum – 2016) BOTTOM LEFT Another stunning hybrid between Nursalim flasher wrasse (Paracheleinus nursalim – 2008) and a closely related...