Speciation
Biologists consider physiology, biochemistry, behaviour and genetics
when distinguishing one species from another.
Biological Species:
When some members of a _________ reproducing population change
so much that they can ___ longer ________ viable/fertile offspring
then ___________ has occurred. __________ is the formation of
new species from existing species.
When various factors or __________ cause ______ changes within a
population, it is called ____________ (ie genetic drift, mutations etc).
When _____________ evolutionary changes occur, resulting in the
formation of a ______ species, that is called _____________.
Two populations can become _____________ isolated over time if
there is little to no gene flow between them. Two types of
reproductive isolating mechanisms that prevent gene flow are
_____________ and ________________.
Types of Speciation
Sympatric Speciation
Factors such as chromosomal changes (in plants) and non-random
mating (in animals) alter gene flow. This type of speciation is far more
common in plants.
A new species can be ____________ in a ________ generation if a
_________ change results in a _____________ barrier between the
offspring and parent population. (ie mutations in DNA -deletion or
addition of DNA).
_____________ results from ________ in ________ where
the offspring has _____ sets of chromosomes. Large numbers
of plants can result in this condition since plants can self
pollinate.
Two species can _________ to produce a _________ offspring
but the offspring can reproduce asexually resulting in the
formation of a separate population. If an error occurs in meiosis
of this new population then the sterile hybrids can be
transformed into fertile individuals. IE. Wheat is a hybrid of
two grasses.
Allopatric Speciation
Occurs when a ___________ is ______ into ____ or more ________
groups by a __________ barrier. Eventually the ___________ of the
split population becomes so _______ that the two groups are ______
to _________ even if they were brought back together.
Geographic barriers include:
Once populations are isolated gene frequencies begin to diverge
due to natural selection, mutation, genetic drift or gene flow.
Darwin’s _________ are an example of _________________
and __________ _____________. Adaptive radiation is a type
of allopatric speciation in which the original species is
diversified into a variety of differently adapted species. When
finches arrived on the Galapagos Islands they were the only
_____ ______ on the islands and therefore had many ecological
niches to move into and adopt. Individual finches were
subjected to __________ selective pressures and as a result
over time the species _______ into _________ populations and
some into ____ species altogether.
Consequences of Human Activities on Speciation
We may be preventing gene flow causing the bottleneck
effect/extinction
Develop wilderness areas for recreation and tourism
Urban subdivisions
Flood large areas of land to build dams for hydroelectric power