What are the problems in defining a species?

Answer 1

The problem is
- Species is a category made up by humans to make the world easier to manage, and understand. It is not a "natural" thing. As you will see in the next three points the living world can be too continuous.
- Lots of scientists are having problems because different populations that look similar and act similar can't interbreed... and others could but total take up a different niche in their environment and look totally different, but still are worth calling the same species.
-Talking about the miss notion of breeding individuals are the same species (see below why it not the true definition). There are populations that live nearby, can breed, fill similar niches and the same species as the population adjacent to them and those to the ones adjacent to them... and so on. These birds live by a large mountain and so the populations form kind of a ring around the Mt. When the populations join up again at the other side of the Mt. they don't look the same or can't even breed. They are definitely a different species. (Each population was just a little different, almost just as much as an individual would in each population.) So where does the species change?
- According to evolution all things came from a common ancestor. So where do species "divide" ... We assume that lion cub come from lion moms and monkey babies come from monkey moms. If we go back in time we see that "the species" was different from the previous one... at what point in evolution is there a new species? Is the ancient monkey mom the same species as the new baby monkey? Surely not. Neither are all its descendents (Since it’s descendents could be both all humans and chimps) and lions and monkeys are different species too, and their common ancestor was the first mammal.
-So how many mutations does one species need to be another species? Actually sometimes only one great big one and in other cases millions can't separate the species.

****The breeding definition is one for populations not necessarily species and even at this point it not fully accurate. It would make every female different species of all the other females for one. The second reason is species can be spread out enough that the individuals at the two ends of the area are separated by barriers and can't reproduce.

Biology major- animal behavior, vertebrate zoology class, principals of biology class...

Answer 2

1. Even evolutionists cannot answer this one, because if you read the definition of "species" in 50 different science textbooks, you'll get 50 different answers. Creationists use the term "kind" rather than species. The Bible says that all plants and animals "bring forth after their own 'kind', so that would mean that any animals that can reproduce with each other belong to the same "kind", even if evolutionists would classify them as different "species". We could further extrapolate that "Kind" would mean any animals that can create FERTILE offspring together belong to the same kind. Although lions and tigers, and horses and donkeys are capable of producing offspring, they are sterile. Even in the extremely rare instances where there are fertile hybrids, if one were to breed the two hybrids together, they would produce a purebred of the parents! The offspring would revert back to the original pair - either a purebred lion or tiger, or a purebred horse or donkey. This is a genetic dead-end that God installed to prevent humans from creating new "kinds". Dogs, wolves, coyotes, etc, all belong to the "dog" kind, because they can produce fertile offspring with each other. But you can breed these guys till the cows come home, and you will never, ever get a cat, not in a million years. 2. The Bible says that Noah brought only two of every "kind" of animal on the ark, not "species", and he only brought air-breathing land animals - those that would drown otherwise. It has been estimated that there are about 8,000 different "kinds" of air-breathing land animals. Multiply this by 2 (or by 7, for a handful of animals), and you have approximately 16,000 individual animals, most of which are the size of a dog or cat, on the ark, a boat that had the capacity of 500 train boxcars. More than enough room for all. 3. Before the Flood, there were no oceans, so there were no great expanses of water to cross. After the Flood, when the waters receded, the Ice Age began, during which time the water level dropped significantly worldwide (because the water was tied up in glaciers). We can see today that if the water level were to drop by 150 feet, you could literally walk to any destination on Earth. This is what happened after the Flood, and this is how animals ended up in Australia and the Americas. Then as the Ice Age ended, the water level rose and cut them off from other populations.

Answer 3

I know that one of them is that the ability of two individuals to reproduce is not an all-or-nothing thing. For instance, my 3 siblings have all gotten married and had kids. The kids are coming out weighing 9-11 pounds. If I go and marry a skinny chick, successful birth will not be possible without medical intervention. Does that make me a different species than skinny chick?

Answer 4

That previous definition certainly doesn't apply to things like bacteria and protozoa. There isn't a good universal definition of a species.

Answer 5

For a species, it's an easy definition.

A male and female are part of the same species if they can reproduce, and those offspring are also capable of reproducing.

Answer 6

The definition of a species is very tricky.
The usual definition is animals that can interbreed.
However Lions and tigers and different species yet can interbreed - producing Tions and Ligers.

So can false killer whales and dolphins (producing wholphins), and they are different *genera*.

http://www.creationontheweb.com/content/view/271

The definition of species can therefore seen to be somewhat arbitrary.