Ontogenetic development of adaptive colouration in impalas (Aepyceros)

Impalas (Aepyceros) are unusual among the relatively large-bodied (body mass 50 kg or more) ungulates of the world, in that the adult colouration is approximately present already at birth.

In other words, the colouration of the pelage in impalas is remarkably precocial.

However, not all features of colouration are equally well-developed in neonates.

The aim of this Post is to document and illustrate these chronological (ontogenetic) variations.

LATERAL FLAG:

This flag is undeveloped (i.e. present only in incipient form) in infants.

This means that the lateral flag is perhaps the least precocial of all the patterns described in this Post (https://www.mindenpictures.com/stock-photo-impala-aepyceros-melampus-mother-running-with-her-calf-following-naturephotography-image00630132.html and https://www.dreamstime.com/impala-lamb-masai-mara-national-reserve-young-aepyceros-melampus-kenya-image243636698 and https://www.offset.com/photos/an-impala-and-young-calf-aepyceros-melampus-on-the-edge-of-woodland-963170 and https://www.superstock.com/asset/impala-calf-baby-impala-antelope-wilderness-africa/6001-16208619 and https://www.inaturalist.org/observations/4425491 and https://www.africanflyingadventures.com/life-and-death-in-the-bush-impala/ and https://www.gettyimages.com.au/detail/photo/portrait-of-deer-standing-on-field-kruger-national-royalty-free-image/1425287723?adppopup=true).

ANTERIOR AURICULAR FLAG:

The anterior auricular flag of the impala is precocial. It is complete in infants, before the dark stripes on the buttocks appear (https://www.alamy.com/stock-photo-two-baby-impala-antelopes-in-the-african-bush-29057562.html and https://www.dreamstime.com/royalty-free-stock-photo-impala-antelope-lambs-two-small-aepyceros-melampus-lake-nakuru-national-park-kenya-image40154625).

PEDAL FLAG:

The pedal flag is peculiarly precocial. It is present in infants, despite the expectation that the metatarsal glands are relatively poorly-developed at birth.

https://www.inaturalist.org/observations/165329533

https://www.inaturalist.org/observations/142346786

https://www.inaturalist.org/observations/106255260

https://www.inaturalist.org/observations/9839721

https://www.inaturalist.org/observations/9356668

PATTERN ON BUTTOCKS:

The following nicely illustrates the point that the pattern on the buttocks is not precocial:

https://www.gettyimages.com.au/detail/photo/instinct-royalty-free-image/975807822?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impala-female-with-lamb-urinating-royalty-free-image/57079600?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impala-with-her-young-aepycaros-melampus-masai-mara-royalty-free-image/57255400?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impalas-okavango-delta-botswana-royalty-free-image/1457505003?phrase=african+impala&adppopup=true
https://www.gettyimages.com.au/detail/photo/impalas-okavango-delta-botswana-royalty-free-image/1457504436?phrase=african+impala&adppopup=true

BUCCAL SEMET:

The buccal semet of impalas is so precocial that it is complete at birth (https://www.dreamstime.com/impala-antelope-wilderness-africa-image174751963).

Posted on 2024년 02월 11일, 01시 11분 06초 UTC by