Why does the colouration of the gerenuk (Litocranius walleri) resemble that of the common impala (Aepyceros melampus)?

For some strange reason, the gerenuk (Litocranius walleri) and the common impala (Aepyceros melampus) have similar colouration (see https://www.flickr.com/photos/helenehoffman/49518633298 and https://www.alamy.com/stock-photo-two-baby-impala-antelopes-in-the-african-bush-29057562.html).

This is true despite the fact that the two species are unrelated phylogenetically and differ ecologically, seldom occurring together.

The gerenuk

  • is specialised to forage with upright bipedality,
  • can forgo drinking for years on end, and
  • tends to be solitary.

By contrast, the common impala

  • has not been observed even to prop its forelegs on a plant stem,
  • must drink nearly daily, and
  • is gregarious.

In the narrow zone where the two species share the same landscapes in Kenya, the gerenuk prefers thorn scrub, while the common impala prefers grassland.

Perhaps the gerenuk has come to mimic the colouration of the common impala for protection against predators.

The common impala tends to be abundant where it occurs, while the gerenuk is everywhere scarce. Based on the likelihood that the gerenuk is not as enduring a runner as the common impala, a naive predator might be misled to turn down hunting opportunities after spotting the gerenuk.

However, the following are obvious problems with this explanation.

For example:

Here is a frontier of understanding in Biology, where new hypotheses are needed.

Please also see https://www.inaturalist.org/journal/milewski/49126-detailed-similarities-and-differences-in-the-colouration-of-gerenuk-litocranius-walleri-and-impala-aepyceros-melampus#

Posted on April 07, 2021 06:33 AM by milewski milewski

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