Hi AndrewPD, welcome back
For instance if I had a baby that had green skin that trait could only be passed on through his offspring.
Therefore doesn't that mean that every species can only descend from one pair? Unless two identical species can evolve alongside one another. Unless I'm missing the point somewhere.
What would prevent your baby from breeding with other humans? Would you not agree that skin color, while unusual, would not necessarily make breeding with other humans incompatible. Green skin alone is not enough to cause speciation -- and what you are really asking is how a new species arises if you need breeding pairs.
You may be familiar with basic genetics of reproduction:
father's x fathers's y
mother's x child xx child xy
mother's x child xx child xy
offspring are female male
If this is a brand new mutation, your child with the green skin would gotten the mutation from one of it's parents, it would be heterozygous, with one g (green) and and one n (not green) gene, with similar results:
father's n fathers's g
mother's n child nn child gn
mother's n child nn child gn
offspring are not green green
So only two out of four of your child's offspring - on average - would carry the green gene.
Thus there would be mixed green and not green individuals within the breeding population.
If there later was a situation where the population split, and one daughter population lived where there was a selective advantage for green skin (say in a jungle where it was good camouflage), then it would eventually predominate in that population. If the other daughter population lived where there was a selective advantage to not green skin (say in a desert, where it was a disadvantage), then not-green would eventually predominate in that population.
This would not prevent the two populations from interbreeding in any overlapped habitats (hybrid zones), however the selective pressures in each population over time would add other mutations to the mix in each individual population that were not shared or selected against in the other populations, over time such additional mutations can make the populations incapable of interbreeding.
More likely is that they will soon not see the other population individuals as potential mates and just cease interbreeding even when capable.
Thus after many generations of populations full of breeding individuals, we eventually end up with one population that is green skinned and one that is not.
If there are a million black and white dairy cows with hooves do they all originate from one original cow like creature that had a specific set of mutations to create the current appearance of the dairy cow?
Along with the billions of non-black and white cows, ... who also are descendants of some ancestral even toed mammal, like antelopes and deer, ... and hippos, that
also have split hooves, and which are also even toed ungulates:
ADW: Artiodactyla: INFORMATION
quote:
The artiodactyls are a large and remarkably diverse group of mammals, containing around 220 living species placed in 10 families. The majority live in relatively open habitats, such as plains and savannas, but others dwell in forests, and one group is semiaquatic. Within the order can be found some of the fastest-running mammals, but the Artiodactyla also includes relatively slow and cumbersome species such as pigs and hippos.
Artiodactyls are paraxonic, that is, the plane of symmetry of each foot passes between the third and fourth digits. In all species the number of digits is reduced at least by the loss of the first digit, and the second and fifth digits are small in many. The third and fourth digits, however, remain large and bear weight in all artiodactyls. This pattern has earned them their name, Artiodactyla, which means "even-toed." Artiodactyls stand in contrast to the "odd-toed ungulates," the Perissodactyla, in which the plane of symmetry runs down the third toe.
As I suggested previously, there are two basic groups of ungulates, even-toed and odd-toed, where ungulates are hooved animals. A common odd-toed ungulate is the horse.
Ungulate - Wikipedia
quote:
Ungulates (meaning roughly "being pawed" or "hoofed animal") are several groups of mammals, most of which use the tips of their toes, usually hoofed, to sustain their whole body weight while moving.
Enjoy.
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