What do the four contributions Darwin made mean?

Question

-The nonconstancy of species
-Branching evolution, which implies the common descent of all species
-Occurrence of gradual changes in species
-Natural selection as the mechanism for evolution

Answer 1

In layman's terms, it means that species change over time--they are not fixed types. They evolve into something different.

Also, in cladogenesis, species split. If you look at the evolutionary "tree of life", there is a base that all the branches meet back at. But there have been splits in lineages, and that has led to the present day diversity we see around us.

Anagenesis, or change within a lineage (species) also occurs. Human beings don't look the same as they did 50,000 years ago--they have changed. The changes jusst occur very slowly (generally, though there are exceptions).

Natural selection is the mechanism that explains all these potential changes. This basically says that if there is variation within populations, and that variation is heritable and makes it more or less likely for individuals to survive, there will be selective pressures acting against the less fit individuals and for the more fit individuals. This gives rise to all the outcomes of evolution- differential survival due to heritable variation within natural populations.

Hope this helps!

Answer 2

1. That species change over time.

2. (IMO, the single most important thing to understand about evolution). That new species arise when a single species branches into two. This mechanism explains all of life as an enormouse TREE related by common ancestry ... in the same way that, given enough generations, we can trace *any* two people back through their family TREES to a common ancestor.

3. That it is not necessary for rapid radical changes in an organism ... large changes can come about through slow, gradual, incremental accumulation of many small changes.

4. That a very simple mechanism explains *how* species change (evolve) in nature. Nature "selects" (on average) those individuals with traits that are best suited for their environment, for the passage of those very traits onto offspring.

Answer 3

There is a great website explain it alittle bit.
1. "The first is the non-constancy of species, or the modern conception of evolution itself."

2. "implying the common descent of all species of living things on earth from a single unique origin."

3."Darwin further noted that evolution must be gradual, with no major breaks or discontinuities."

4."the mechanism of evolution was natural selection"

Good luck!