20sep ~ There’s a hole in the bottom of the tree, …

Errata:  I mis-identified the Hummingbird Moth. It is Hemaris diffinis, a Snowberry Clearwing, not Hemaris thysbe the Hummingbird ClearwingBoth qualify as Hummingbird Moths.

Now back to the hole in the tree.

A little literary license, in the subject line.  In truth it is a Treefrog “in a hole, and it is not really in the bottom of the tree”.  If this is nonsense to you it extracted from a little sing-along ditty (Ohhhhh, there’s a hole in the bottom of the sea”that just might be colloquial to children in southern Ohio.  In grad school it concerned me that there are no marine amphibians, so what is the frog doing in a hole in he bottom of the sea?—Myth buster:  It couldn’t happen, but I got over it…mostly…  OK, really, just disregard this nonsense.

This is a treefrog — an Eastern Gray Treefrog (Dryophytes versicolor), or Cope’s Gray Treefrog (Dryophytes chrysoscelis.)  I can’t tell them apart.  Both species used to be in the genus Hyla if that rings a bell.  

While there is some difference between their calls, it requires an expert with a thermometer to tell the difference— or another frog.  They are virtually identical in appearance, but the Eastern species is tetraploid (4N with 48 chromosomes) and Cope’s Treefrog is diploid (2N at 24).  With a little thought it becomes clear that different species look different so they can tell themselves apart.  But if their sensory mechanism is not primarily visual, there is not reason why they should appear different to us.  Clearly not just for out benefit.  

Hybrids are not competitive and so the adults constitute isolated gene pools, and that makes them separate species by definition.  They were one a common form, so if they are going to appear different, some force must push them, and if they produce duds every time they cross that’s a push.  The hybrid would be 3N, a triploid, which are often sterile across the spectrum.  Clearly the treefrogs need to find a way to tell themselves apart, even without MAGA hats.  They are doing it by altering their song as other frog species have done before.  It just isn’t helping us to see any difference.

Treefrogs call (sing) in the trees, males only I presume.  That behavior is a risk and an expense, in which I see no benefit.  They do it for reasons that I’ve never had explained to me, but they still do it, and they are really hard to locate while they sing.  We have one that likes to sing inside of the downspouts — singin’ in the shower.  But his one is in a cavity just off the deck in a redbud—the cavity was excavated this spring by a pair of Black-capped Chickadees, who then abandoned it.

He has an emperor’s view of the arena before him.  And a fine singing platform that is spacious, shaded, out of the wind, and relatively safe.  And an audience, if only of humans.

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