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The Daily Bucket is a regular feature of the Backyard Science group.  It is a place to note any observations you have made of the world around you.  Snails, fish, insects, weather, meteorites, climate, birds and/or flowers.  All are worthy additions to the bucket.  Please let us know what is going on around you in a comment.  Include, as close as is comfortable for you, where you are located.


This is going to be a remote control bucket as I am in Orlando at a workshop today.  However the Bucket seems to be a bit sparsely staffed right now and I thought I should post another, even if I won't be around for it (I will try and answer questions in the evening).

Below are two pictures of lizards I saw last week in southern Utah.  They are both in the genus Aspidocelis.  There are many species in this genus in the western U.S.  Formerly they were in the genus Cnemidophorus but that genus was split in 2002 and all the species in North America are now Aspidocelis.  In the SE and south central parts of the US people may be familiar with the six-lined racerunner.  It is the only species to occur east of the Mississippi.  Species diversity is highest in New Mexico and Arizona.

Whatever their name they are interesting lizards to watch.  Similar to skinks they are active foragers, moving about and searching for food largely by smell.  They are much more active than most skinks and have very high preferred body temperatures.  So in areas where they do occur they are often conspicuous in the summer as being the only lizards out in the heat of the day.

The really interesting thing about these lizards is that a number of the species are unisexual, consisting only of females that reproduce through parthenogenesis.  Parthenogenesis refers to producing eggs that are genetically identical to the parent.  These eggs develop without fertilization.

This is A. tigris, the Western Whiptail, one of the most widespread species.  It is a bisexual species with both males and females.

Western Whiptail
The is A. velox, the Plateau Striped Whiptail.  It is a unisexual, all female species.
Plateau Whiptail
The unisexual species all appeared to have evolved as a result of hybridization between two different species.  The offspring end up with the chromosomes from two different species that don't work together properly in meiosis (when eggs and sperm get made). Aspidocelis velox is the result of hybridization between A. inornatus and another hybrid (no longer in existence).  All the descendants of one hybrid event would be clones (genetically identical).  Checking on this it has been found that some of the unisexual species consist of several clones indicating multiple origins.

One aspect of these lizards' biology that is particularly interesting from a sociopolitical as well as biological angle is their sexual behavior.  Back in the 1980s lab researchers reported unisexual individuals performing 'pseudocopulation'.  Field workers were dismissive of this, considering a lab artifact.  Because these animals are highly mobile and not very territorial it is difficult to observe much in the way of social interactions in the field.  I haven't looked into this in detail but I have gathered that since that time it has been learned that the pseudocopulation is a normal and perhaps necessary part of the unisexual species' behavior.

That's it from me.  What's going on in your neck of the woods.



"Green Diary Rescue" is Back!

After a hiatus of over 1 1/2 years, Meteor Blades has revived his excellent series.  As MB explained, this weekly diary is a "round-up with excerpts and links... of the hard work so many Kossacks put into bringing matters of environmental concern to the community... I'll be starting out with some commentary of my own on an issue related to the environment, a word I take in its broadest meaning."

"Green Diary Rescue" will be posted every Saturday at 1:00 pm Pacific Time on the Daily Kos front page.  Be sure to recommend and comment in the diary.

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