Date: 8/22/20 12:13 am From: <nw105...> <dmarc-noreply...> (Redacted sender nw105 for DMARC) Subject: [obol] Tan- vs White-morph White-striped Sparrows
It’s been known for a while that the tan-morph (tm)of this species is less aggressive than the white-morph (wm)White-throated Sparrow. When confrontedwith recordings of seeming territorial intruders, wms morphs sing more songsand for longer periods. Both male andfemale wms seek more extra-pair copulations and both male and femalewms sing; male tms practice more mate-guarding from extra-paircopulations and both male and female tms attend more to nestlings. (The famous tm x wm pairingsare most likely to involve a tm male and a wm female.) Thus the two morphs are pursuing distinctreproductive strategies: reproductive quantity vs offspring care quality.
It’s now known that wm behavior is under the controlof a single estrogen receptor gene in a block of genes (a super-gene) that becameinverted at some point during a historical chromosome reproduction event. The chromosome broke and when it reassembleditself, this block of genes was re-inserted ‘upside down’ as it were. This has been tested both in the field andthe lab. < https://academic.oup.com/condor/article/101/4/842/5124234>
Nathaniel WanderPortland, OR
"This is my home, this is my only home/ This is the only sacred ground that I have ever known/ And should I stray in the dark night alone/ Rock me Goddess in the gentle arms of Eden" Dave Carter & Tracy Grammar, "Rock Me Goddess in the Gentle Arms of Eden" <https://www.youtube.com/watch?v=bAGMATHlSK4>