Download Speciation

ScienceShot: Dad's Odor Splits a Species
Key words: Sexual imprinting (male/female), (phenotype), speciation ,(species),
ecological speciation, divergence (separating)
http://www.youtube.com/watch?v=cgPqmRNjoTE
Octopus Garden
What is dad Stickleback doing in this picture?
He is guarding and caring for the eggs and fry as this deep-water form of stickleback is doing. The females of both types lay
their eggs in an algae nest the male builds.
How does the Stickleback species change when
divergence takes place?
Researchers studied two groups of the same species that ecologically separated. One lives in shallow water, the other in
deep water. Evidence suggests ecological separation keeps species from mating. Some of the first evidence that sexual
imprinting can drive speciation.
Girls, do you want a guy that looks like dear old dad?
Stickleback daughters want one who smells like him. Researchers have found that in two species of the fish from British
Columbia's Paxton Lake, daughters learn who to choose as a mate based on their father's smell, a form of sexual imprinting.
Sexual imprinting
Offspring learn parental phenotypes and then select mates who are similar to their parents.
Speciation
“In any normal species there is some geographical variation through the range of the species. Some of this must be purely
random variation, but typically geographic variation has some ecological pattern to it.”
Speciation
“In any normal species there is some geographical variation through the range of the species. Some of this must be purely
random variation, but typically geographic variation has some ecological pattern to it.
Speciation
The Western meadowlark (left) and the Eastern meadowlark (right) appear to be identical, and their ranges overlap, but
their distinct songs prevent interbreeding. (CalBerkley)
How might the dads be different in the deep water as
compared to the dads in shallow water? Why won’t the
daughters of the deep chose a mate from the males of
the shallow and vice versa? Male imprinting?
Consider the different environments, adaptation as well as genetic traits over the generations.
Sexual imprinting
Offspring learn parental phenotypes and then select mates who are similar to their parents.
Now
• Let’s read part of the abstract from the
researcher study to see if what they wrote
makes sense.
Abstract (Genevieve M. Kozak1,*†, Megan L. Head2 and
Janette W. Boughman3
• “Daughters imprinted on father odor and color
during a critical period early in development.
These traits have diverged between the species
owing to differences in ecology. Therefore, we
provide the first evidence that imprinting links
ecological adaptation to sexual isolation between
species. Our results suggest that imprinting may
facilitate the evolution of sexual isolation during
ecological speciation, may be especially
important in cases of rapid diversification, and
thus play an integral role in the generation of
biodiversity. “
Speciation discussion on the Zonkey or Zedonk
How did this happen?
What about the Grolar?
How did this happen?
Is this real?
Speciation
• For example, birds may vary their nesting habits according
to the trees available. Most geographic variation is the
result of local adaptation to local environments, which in
turn reflects some degree of genetic divergence between
the separated populations. That genetic divergence will not
lead to a species divergence, as long as genes flow (at some
level) between the members of the species throughout
their range. Gene flow is naturally much easier among
individuals of a local population than between local
populations, and much easier between adjoining
populations than separated ones. Obviously, gene flow
from neighboring populations acts against local
adaptation.”
Speciation
• “Suppose now that for some reason or other there is a
complete geographic separation between parts of the species
range. Gene flow from the other parts of the range stops, and
the separated populations evolve to suit their new, restricted
environment. This encourages the genetic divergence of the
separated populations, and might become so great that if the
two populations were rejoined they would no longer be
successful at interbreeding. [Even if limited interbreeding
were still possible, the local adaptations might have become
so advantageous that there would be strong selection for
individuals to discriminate in order to mate preferentially with
members of their local population, rather than with
immigrant individuals.] The two sets of organisms have
become new species because of the physical and genetic
separation of the populations which, in theory leads to
speciation.”
http://mygeologypage.ucdavis.edu/cowen/historyoflife/speci
ationmode.html
Explore Speciation
Wikipedia: Speciation
http://en.wikipedia.org/wiki/Speciation
Understanding Evolution – Speciation:
http://evolution.berkeley.edu/evosite/evo101/V
Speciation.shtml
TalkOrigins: Observed Instances of Speciation
http://www.talkorigins.org/faqs/faqspeciation.html