Transcript Speciation and Extinction

Warm-Up (2/11)
On the piece of white paper from the back, answer
the following question.
(w+)
You read about fruit flies having red
or
white (w--) eyes in last week’s CTQ’s. Flies
without red pigment have a mutation in the
white gene (w--); flies with the red pigment are
considered wild-type (w+). Explain how the
allele frequency should change over the
course of five generations of a population with
an equal distribution of red- and white-eyed
flies, if w+ allele has a selective advantage.
Name
Date
Period
2D.3b: Disruptions to ecosystems impact the dynamic homeostasis or balance of
the ecosystem.
Illustrative example: natural disasters
1C.1a: Speciation rates can vary, especially when adaptive radiation occurs when
new habitats become available.
1C.1b: Species extinction rates are rapid at times of ecological stress.
Illustrative example: Five major extinctions
1C.2a: Speciation results in diversity of life forms. Species can be physically
separated by a geographic barrier such as an ocean or a mountain range, or
various pre- and post-zygotic mechanisms can maintain reproductive isolation and
prevent gene flow.
1C.2b: New species arise from reproductive isolation over time, which can involve
scales of hundreds of thousands or even millions of years, or speciation can occur
rapidly through mechanisms such as polyploidy in plants.
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
(1) Physically isolated.
Romeo!
Juliet!
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
(1) Physically isolated.
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
Eww…
feathers!
(1) Physically isolated.
(2) “Pre-zygotically” isolated
(cannot/will not mate)
Eww…
bald!
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
¡ay
caramba!
(1) Physically isolated.
(2) “Pre-zygotically” isolated
(cannot/will not mate)
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
(1) Physically isolated.
(2) “Pre-zygotically” isolated
(cannot/will not mate)
(3) “Post-zygotically”
isolated (offspring dead
or sterile)
Speciation
Speciation occurs when two
groups become reproductively
isolated from each other.
(1) Physically isolated.
(2) “Pre-zygotically” isolated
(cannot/will not mate)
(3) “Post-zygotically”
isolated (offspring dead
or sterile)
Chromosomes
don’t match up!
Speciation
Speciation can happen
quickly (like in plants)…
Generation 1
No genetic
change
Whole-genome
duplication
Generation 2
Speciation
Speciation can happen
quickly (like in plants)…
Let’s start
eating fruits
more!
…or slowly (like when
groups find a new
environment).
Let’s start
eating fish
more!
Critical Thinking Question #1
A population of tree monkeys is only found in a remote
forest of Ecuador. In 2005, a drought led to massive forest
fires, greatly diminishing the tree monkey population.
Describe how speciation could occur in the tree monkey
population in the context of genetic drift following the forest
fire. (LO 1.24) (LO 2.28)
2D.3b: Disruptions to ecosystems impact the dynamic homeostasis or balance of
the ecosystem.
Illustrative example: natural disasters
1C.1a: Speciation rates can vary, especially when adaptive radiation occurs when
new habitats become available.
1C.1b: Species extinction rates are rapid at times of ecological stress.
Illustrative example: Five major extinctions
1C.2a: Speciation results in diversity of life forms. Species can be physically
separated by a geographic barrier such as an ocean or a mountain range, or
various pre- and post-zygotic mechanisms can maintain reproductive isolation and
prevent gene flow.
1C.2b: New species arise from reproductive isolation over time, which can involve
scales of hundreds of thousands or even millions of years, or speciation can occur
rapidly through mechanisms such as polyploidy in plants.
Extinction
Extinction is the
elimination of a species…
…caused by destabilization of
an ecosystem.
Fleenzauts
Fleenzarks
Extinction
There have been five
major mass extinctions
caused by massive
climate change.
Scientists have declared Earth is
currently experiencing a sixth mass
extinction.
Extinctions have occurred at
over 1,000 times the
background extinction rate
since 1900.*
*Malcom et al, 2015
Critical Thinking Question #2
201.3 Million years ago (Ma), most marine
and terrestrial species became extinct in
what is known as the Triassic-Jurassic era.
Other species, such as crocodylomorphs,
were greatly reduced in population size
and genetic variation. Explain how the
aftermath of this extinction event might
have led to new speciation events.
Closure
On the piece of white paper from the
back, answer the following question:
State three situations in which a
population could separate into
two species.
Name
Date
Period
Scale
1 – 10