Download Members of a species may be reproductively isolated in separate

Species
Horse
Donkey
Mule
Members of a species may be reproductively isolated in separate
populations.
New species arise when one existing species splits into two reproductively
isolated populations that go their separate ways.
This most commonly happens when the two populations become
physically separated from each other (allopatric speciation)
e.g. The genome map suggests that about 2 million years ago, individuals
of a single ape species were divided by the Congo River.
The populations must be reproductively isolated, so that they could not
interbreed and there was no gene flow between the groups.
As the environmental conditions were different on either side of the river
they started evolving separately.
Chimpanzee
Bonobo
The allele frequencies in the two populations became
different. They became separate species — chimpanzees and
bonobos — about 1 million years ago.
Bonobos have a genome which is 99.6 percent identical to the
chimpanzee genome and 98.7 percent identical to the human
genome — basically they are just as related to humans as
chimpanzees.
Photoautotrophic organisms use
light as an energy source which
enables them to synthesise their
own organic molecules
(photosynthesis).
Chemoautotrophs use the energy from reduced
compounds, which they oxidise, to enable then to
synthesise organic materials
e.g. NH4+ -> No3- + 3H
H2 + CO2 -> CH2O + O2 (not balanced)
Ecosystems have the potential to be sustainable over long periods
of time
Many different factors interact to determine population size, and it can
be very difficult to determine which factors are the most important.
These factors can be split into two broad groups:
Abiotic Factors: Non-living components of the environment; e.g.
Temperature, Humidity, pH, altitude. These factors tend to control a
population in a density independent manner.
Biotic Factors: Living components of the environment, as all living
things compete, these factors tend to be density dependent. e.g.
competition for mates, territories, are forms of competition within a
species i.e. intra specific competition.
An organism’s niche refers to the biotic and abiotic factors that the
organism needs in its habitat.
Mixotroph
Detritivore: an organism that ingests non-living organic
matter.
Saprotroph: an organism that lives
on or in nonliving organic matter,
secreting digestive enzymes into it
and absorbing the products of
digestion.
Consumer: an organism that ingests other organic
matter that is living or recently killed.