Change over time
Three types of Species
a group of organisms in which individuals are members of the species if they sufficiently conform to certain fixed properties.
The clusters of variations or phenotypes within specimens (i.e. longer or shorter tails) would differentiate the species. (The way they look)
This method was used as a "classical" method of determining species, We now know that different looks do not always mean different species
If an organism has a single evolutionary lineage of organisms within which genes can be shared, and that maintains its integrity with respect to other lineages through both time and space, then it is considered a species.
At some point in the evolution of such a group, some members may diverge from the main population and evolve into a subspecies, a process that may eventually lead to the formation of a new species if isolation (geographical or ecological) is maintained.
A group of organisms that shares an ancestor; a lineage that maintains its integrity with respect to other lineages through both time and space.
At some point in the progress of such a group, members may diverge from one another: when such a divergence becomes sufficiently clear, the two populations are regarded as separate species.
This differs from evolutionary species in that the parent species goes extinct taxonomically when a new species evolves, the mother and daughter populations now forming two new species.
It gets ruined, or for this conversation, it erodes; it deteriorates.
Fossils only tend to form (be preserved) in fairly restricted conditions, so a lot of stuff simply never gets preserved as fossils.
This is what geographers, anthropologists, biologists think has happened to many of the fossils. They believe that they have eroded away and that we will never be able to have a complete fossil record.
According to a study done in 2011 (see Appendix (Species Count)) there are 8.7 million species ACCOUNTED FOR!!!
With 86% of existing species on Earth and 91% of species in the ocean still awaiting description!!!
The correct answer to this question is we have no idea…there are so many that we have not been able to count, and will probably never be able to count.
If I had to guess, I would probably put the number at around 75-100 million.
Evolution Definition Today
genetic change in populations of species over time
key words being GENETIC change and POPULATIONS
The actual genes of the species change, AND, its changing at the population level, not the individual level.
Three main causes of changes in genetic makeup
different success in reproduction by different phenotypes resulting from interactions with the environment.
In other words, the environment naturally selects those who are more adapted to the environent, and these species will pass on their genes while those not adapted well enough will not.
The environemtn will naturally select, not the species...dont get this mixed up. Species are out there, "looking to get better" it happens naturally.
If the environment changes to where those with long necks will survive, the species will naturally go that route. cold, warm, skinny, heavy, big beaks, small claws; it doesnt matter.