DIVE DRY WITH DR. BILL #884: WE'RE ALL ONE... SPECIES
I've often written about my concern with taxonomists who are splitters. I'm referring to those who decide a critter is a new species because it has an addition spot, stripe or bar on its body. Some simply want an individual to represent a new species so they can add their name to it. I tend to favor lumpers who recognize the diversity within a species and accept variability.
Fortunately morphology is no longer the end-all for those who spend their lives trying to make sense out of the myriad critters in this world. Thanks to molecular genetics, we can now look at the genes within a group of organisms and decide whether they represent the same species, or a cluster of several different but related ones. Of course using genetics still involves making human judgment calls on what constitutes a species, but at least it is a more fundamental base to work with.
Even if I don't recall what I ate for breakfast yesterday, I remember way back in the late 1960s when I arrived on Catalina to teach marine biology. At the time marine botanists thought we had a unique species of elkhorn kelp, Pelagophycus giganteus, that was distinct from the "normal" species, Pelagophycus porra. As I remember, it had a much shorter stipe and somewhat different holdfast... both structural (morphological) characters. Later biologists realized that these were the same species and just represented differences in the ecological conditions where they grew.
Our giant bladder kelp was also thought to be four different species, Macrocystis pyrifera, M. integrifolia, M. laevis and M. angustifolia. These species were scattered across North America, South America, Australia and South Africa. When I got to graduate school at UCSB under world renowned kelp biologist Dr. Michael Neushul, there was talk of a new classification of the kelp based on the relatively new science of molecular genetics.
As a result of these studies, the four "species" of Macrocystis were subsumed into the single species M. pyrifera. Each variant was considered to be a reflection of the ecological conditions in which it grew. We call these variations ecotypes. They are not separate species, but simply reflect variability within a single species. Our own species, Homo sapiens, reflects tremendous variability in many characteristics including skin color, hair color, eye color, height, body shape, etc.
Unless there is good evidence for the splitting of populations into separate species, I tend to favor the recognition of variability within a species. Sadly, we humans need to accept this to a greater degree and realize we are all one.
© 2020 Dr. Bill Bushing. For the entire archived set of nearly 900 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Elkhorn kelp (Pelagophycus porra); and giant bladder kelp (Macrocystis pyrifera).
I've often written about my concern with taxonomists who are splitters. I'm referring to those who decide a critter is a new species because it has an addition spot, stripe or bar on its body. Some simply want an individual to represent a new species so they can add their name to it. I tend to favor lumpers who recognize the diversity within a species and accept variability.
Fortunately morphology is no longer the end-all for those who spend their lives trying to make sense out of the myriad critters in this world. Thanks to molecular genetics, we can now look at the genes within a group of organisms and decide whether they represent the same species, or a cluster of several different but related ones. Of course using genetics still involves making human judgment calls on what constitutes a species, but at least it is a more fundamental base to work with.
Even if I don't recall what I ate for breakfast yesterday, I remember way back in the late 1960s when I arrived on Catalina to teach marine biology. At the time marine botanists thought we had a unique species of elkhorn kelp, Pelagophycus giganteus, that was distinct from the "normal" species, Pelagophycus porra. As I remember, it had a much shorter stipe and somewhat different holdfast... both structural (morphological) characters. Later biologists realized that these were the same species and just represented differences in the ecological conditions where they grew.
Our giant bladder kelp was also thought to be four different species, Macrocystis pyrifera, M. integrifolia, M. laevis and M. angustifolia. These species were scattered across North America, South America, Australia and South Africa. When I got to graduate school at UCSB under world renowned kelp biologist Dr. Michael Neushul, there was talk of a new classification of the kelp based on the relatively new science of molecular genetics.
As a result of these studies, the four "species" of Macrocystis were subsumed into the single species M. pyrifera. Each variant was considered to be a reflection of the ecological conditions in which it grew. We call these variations ecotypes. They are not separate species, but simply reflect variability within a single species. Our own species, Homo sapiens, reflects tremendous variability in many characteristics including skin color, hair color, eye color, height, body shape, etc.
Unless there is good evidence for the splitting of populations into separate species, I tend to favor the recognition of variability within a species. Sadly, we humans need to accept this to a greater degree and realize we are all one.
© 2020 Dr. Bill Bushing. For the entire archived set of nearly 900 "Dive Dry" columns, visit my website Star Thrower Educational Multimedia (S.T.E.M.) Home Page
Image caption: Elkhorn kelp (Pelagophycus porra); and giant bladder kelp (Macrocystis pyrifera).
