All-Female Species, High school
In some species of lizards, snakes, fish and salamanders, every adult is female. There are zero males.
Could a species with no males keep having babies for thousands of years?
In the video, Raven says parthenogenesis is making babies without fertilization.
Why does a baby made by parthenogenesis carry nearly the same DNA as her mom?
Lampert and Schartl note that mutations, small changes in DNA, still produce new genotypes in all-female species.
What can make the DNA of a baby made by parthenogenesis differ slightly from her mom’s?
The Amazon molly and some all-female salamanders need sperm from a male of a related species to start their eggs.
What happens to the male’s DNA in an Amazon molly baby and in an all-female salamander baby?
What evidence in an all-female salamander baby’s DNA would show that some of the male’s genes were kept?
Whiptails don’t need males, yet two females sometimes act out mating behavior.
In a controlled experiment on whether mating-like behavior helps whiptails reproduce, which variable should you change?
In a controlled experiment on whether mating-like behavior helps whiptails reproduce, which variable should you measure?
Which result would show that mating-like behavior helps whiptails reproduce?
Why would a two-sex snake species carried in a flowerpot be less likely to start a new population than the Brahminy blind snake?
Claim, evidence, reasoning
Every adult Amazon molly is female, but she needs sperm from a male of a related species to start her eggs.
Which claim about the Amazon molly fits the evidence best?
Claim, evidence, reasoning
Which evidence best backs the claim that the Amazon molly is all female even though she needs sperm?
Claim, evidence, reasoning
Which reasoning best links the evidence to the claim about the Amazon molly?
Claim, evidence, reasoning
Which question about Amazon molly babies would best test the claim that the male’s DNA almost never joins the egg’s DNA?
In New Mexico whiptail lizards, the egg cells that become eggs start meiosis with twice the usual number of chromosomes, and identical copies pair up with each other.
Why does pairing identical copies keep a whiptail baby’s gene mix the same as its mom’s?
What does a two-parent baby get that neither a whiptail baby nor Coquita’s baby gets?
In the video, Raven says two female whiptails act out mating-like behavior, and the behavior helps trigger ovulation, the release of eggs. In a 1986 study, David Crews’s lab housed females of an all-female whiptail species with one partner each. 18% ovulated when the partner couldn’t act male, and 66% ovulated when the partner acted male.
Why would two female whiptails act out mating-like behavior?
Why would natural selection keep mating-like behavior in an all-female whiptail species?
Lesson complete
Today’s word
unisexual
yoo-nih-SEK-shoo-ul
Having only one sex. Every unisexual animal with a backbone that scientists have found is all female.
Look at these again
You got every question right the first time.
Sources
- Aracely Lutes, Peter Baumann and colleagues, Stowers Institute, Nature, 2010
- A. A. Newton, P. Baumann and colleagues, Development, 2016
- David Crews, Mark Grassman and Jonathan Lindzey, University of Texas at Austin, PNAS, 1986
- Yuan Lu, Wesley Warren, Manfred Schartl and colleagues, Genome Research, 2021
- Review by Kathrin Lampert and Manfred Schartl, BMC Biology, 2010
- Florida Museum of Natural History, Florida snake ID guide
- Toronto Zoo, Desert grassland whiptail page
- The Reptile Database, Aspidoscelis uniparens entry
- Vision and Change core concepts and competencies, as summarized in Brownell and others, CBE Life Sciences Education, 2014
- Word origins from Dictionary.com: unisexual, uni-, unison, gynogenesis, gyno-, kleptomania