21 de julio de 2024

The exceptional nature of the reticulated giraffe (Giraffa reticulata) in its genus, and how we risk extinction of the real animal via complacency given the successful conservation of its hybrids


The reticulated giraffe (Giraffa reticulata) is an extreme animal, beyond the extreme nature of giraffes generally.

As a distinct species, the reticulated giraffe is the largest-bodied terrestrial animal on Earth that possesses camouflage-colouration at the scale of the whole body.

This thoroughly camouflaging colouration is all the more remarkable, because the reticulated giraffe is the only member of its family that is not subject to the 'xeric pallor' typical of semi-arid environments (https://www.merriam-webster.com/dictionary/xeric and https://academic.oup.com/bioscience/article/55/2/125/221478?login=false and https://www.perplexity.ai/search/please-give-several-good-refer-lXsUKVZtSFG3dgUZ7Hue4Q).


In this Post, I

  • explain why the reticulated giraffe is categorically distinct from other giraffes,
  • show that the most secure populations labelled as the reticulated giraffe are hybrids,
  • point out a psychological principle whereby human resolve to conserve the real species might be diminished, and
  • call for renewed efforts to secure the species in the heartland of its original distribution.


The reticulated giraffe differs in colouration from other spp. of giraffes in at least three ways, viz. it

  • is the only giraffe - and the only terrestrial mammal - that has camouflage-colouration in the form of a crisp, contiguous network of pale overlaying a dark ground-colour,
  • is the only giraffe adapted to semi-desert that shows no 'xeric pallor',
  • lacks most of the conspicuous patterns/features of colouration seen in other giraffes.

The important point is that the reticulated giraffe is not just another version of a palette of variations within a single theme, in the genus Giraffa. Instead, it is in 'a class of its own'.


There are three forms of giraffe that are adapted to semi-deserts, viz.

  • Giraffa camelopardalis peralta, which formerly occurred in what is now the Sahara,
  • Giraffa giraffa angolensis, which to this day occurs at the edge of the Namib Desert and in the most arid part of the Kalahari, and
  • the reticulated giraffe.

The difference is that only the reticulated giraffe, of the three forms above, shows no 'xeric pallor'.

The 'xeric pallor' of the northern and southern forms of giraffes differs as follows.

In G. c. peralta, the 'xeric pallor' arises from a broadening of the matrix/ground-colour, at the expense of the blotches. The matrix/ground-colour is pale, whereas the blotches are dark.

The overall pallor seen in G. c. peralta and G. g. angolensis fits poorly into the concept of camouflage, despite the fact that 'xeric pallor' in small-bodied mammals, birds, and reptiles is well-known to enhance adaptive inconspicuousness. This is because

  • there are too few trees in the Sahara/Sahel, the southwestern Kalahari, and the edge of the Namib for any giraffe to blend into a background of trees, and
  • the animals tend to be so pallid that they stand out from treeless backgrounds.

In the case of the reticulated giraffe, the adaptive relationship is basically different. This is because

  • there is no 'xeric pallor' of either of the two kinds described above, and
  • the typical vegetation it inhabits remains wooded despite occurring in a climate with as little rainfall, on average, as 80 mm per year.

The vegetation with which the reticulated giraffe is associated (for example near Wajir and Garissa in Kenya) is 'acacia-Commiphora woodland'. This vegetation is remarkably tall and dense for a semi-arid (average annual rainfall about 250 mm per year) to arid (<100 mm per year) climate.

What is congruent with the anomalously tall and dense vegetation of its habitat is the adaptive colouration of the reticulated giraffe, in particular

  • the unique pattern (reticulated and with an 'inversion' of the usual relationship between 'matrix/ground-colour' and overlaying markings), and
  • the lack of most of the conspicuous features that are nested within the overall pattern in other giraffes.


I have previously pointed out six flags in the adaptive colouration of giraffes (https://www.inaturalist.org/journal/milewski/48447-conspicuous-features-of-colouration-in-giraffes).

Of these, the reticulated giraffe possesses

  • only two of the six, viz. the caudal flag (blackish) and the posterior auricular flag (whitish), and
  • the sole pale flag (viz. the posterior auricular flag) is the smallest of all the flags possessed by giraffes.

The downplaying of flags in the colouration of the reticulated giraffe is consistent with its commitment to thorough camouflage.

Publicado el 21 de julio de 2024 a las 02:20 PM por milewski milewski | 2 comentarios | Deja un comentario

Are clonal aphids (Aphididae) meta-eusocial?

Everyone knows that certain aphids (Aphididae, https://en.wikipedia.org/wiki/Aphid) reproduce largely by parthenogenetic (= clonal) means (https://en.wikipedia.org/wiki/Parthenogenesis and https://onlinelibrary.wiley.com/doi/pdf/10.1042/BC20070135).

However, what is somewhat unappreciated is the puzzle that this raises.

Most other insects that reproduce parthenogenetically (= clonally), beyond Hemiptera, are eusocial (https://en.wikipedia.org/wiki/Eusociality and https://www.researchgate.net/publication/30947830_The_definition_of_eusociality).

Is it really true that aphids have evolved to be able to reproduce largely parthenogenetically (= largely clonally) despite lacking eusociality?

In this Post, I argue that one way to view aphids is as 'meta-eusocial' insects.

The rational goes as follows.

All of the clonal aphids are dependent on ants (Hymenoptera: Formicidae), in a mutualistic relationship.

This trophobiotic (https://en.wikipedia.org/wiki/Trophobiosis) relationship involves more than mere protection from predators and parasitoids. This is because ants tend/husband aphids in more profound ways, analogous to the relationship between Homo sapiens and livestock (https://www.youtube.com/watch?v=KcPcT7dJ3Hc and https://www.youtube.com/watch?v=BigxxBfjaYc).

Indeed, it might be impossible for aphids to reproduce parthenogenetically without their intimate relationship with ants.

Most of the ants that tend aphids are eusocial, and reproduce parthenogenetically. This is significant, despite the fact that in most cases the individual aphids greatly outnumber the individual ants at any one site.

What this means is that the reproductive modes of aphids reflect the eusociality of the mutualism-partners that are crucial for the ecological success of the aphids.

Aphids can be viewed as meta-eusocial, in the sense that their reproductive mode is congruent with, and an 'extension of', that of the ants.

Publicado el 21 de julio de 2024 a las 12:42 AM por milewski milewski | 4 comentarios | Deja un comentario

17 de julio de 2024

Illustrations of sexual dimorphism in Hippopotamus amphibius









Adult females:




Adult males:









Publicado el 17 de julio de 2024 a las 11:44 PM por milewski milewski | 1 comentario | Deja un comentario

Why is there no such thing as a migratory carnivore?

Publicado el 17 de julio de 2024 a las 01:46 AM por milewski milewski | 0 comentarios | Deja un comentario

13 de julio de 2024

12 de julio de 2024

Colouration of Gazella pelzelni

I have adopted Gazella pelzelni as a standard, for my studies of adaptive colouration in Gazella and Eudorcas.


I disregard all hues, focussing only on pale/dark differentiations.

I estimate tone (from pale to dark) on a scale of 1-10. 1= white, 10= black, and thus 5= medium 'grey'.

All numbers in this Post refer to this tonal scale.

'dark' flank-band up to 7

'pale' flank-band about 3.5

dorsal panel 4 up to 5

ischial stripe (vertical) 5

neck about 4

ventral haunch about 4

outer surface of lower foreleg 4
posterior surface of lower foreleg 2
outer surface of lower hindleg 3.5-4
outer surface of upper foreleg at least 5

shoulder about 5

malar stripe up to 8

chin 1

pale facial stripe, medial to eye 1
pale facial stripe, on side of rostrum 2-3

forehead up to 6

cheek about 3

nasal about 4

tail 9

root of tail 7

Dark rostral spot minimal in adult male, present in adult female



Publicado el 12 de julio de 2024 a las 09:50 PM por milewski milewski | 1 comentario | Deja un comentario

09 de julio de 2024

A new term for an important biological phenomenon: introducing 'secromorphosis' as categorically distinct from metamorphosis

@tonyrebelo @jeremygilmore @ludwig_muller @jwidness @thebeachcomber @lupoli_roland @wongun @nomolosx @mpintar @kgrebennikov @lehelind @andreyperaza @hemala_vladimir @hopperdude215 @nmhernandez @dan_johnson @psyllidhipster @gernotkunz @beetle_mch @mydadguyfieri @lrubio7 @bnormark @darwinnie @rjpretor @entomike @mathieu_h @benwx @elytrid @megachile @extasiptera @tmvdh @easmeds @pfau_tarleton @szucsich @teuthis

Before reading this Post, please watch https://www.youtube.com/watch?v=3EVLJChVV48.

Everyone knows that

However, there is another process whereby the bodies of arthropods are radically modified. This deserves a term of its own: secromorphosis.

[As a necessary digression, please note a terminological quirk. The biological adjective derived from the noun 'metamorphosis' is 'metabolous', not 'metamorphic'. Likewise, those derived from holometamorphosis and hemimetamorphosis are respectively holometabolous and hemimetabolous. In accordance, the adjective derived from my new term - albeit unsatisfactory owing to some ambiguity with metabolism - would be secrobolous, not secromorphic.]

In metamorphosis,

By contrast, in secromorphosis, the transformation of the body - which can be extreme (https://lostcoastoutpost.com/nature/5938/ and https://australian.museum/learn/animals/insects/giant-female-scale-insects-and-bird-of-paradise-flies/ and https://www.ecoorganicgarden.com.au/problem-solver/how-to-control-lerps/ and https://www.dpi.nsw.gov.au/agriculture/horticulture/citrus/content/insects-diseases-disorders-and-biosecurity/insect-pest-factsheets/long-tailed-mealy-bug#:~:text=Description&text=Adults%20are%203%E2%80%934%20mm,a%202%E2%80%933%20week%20period. and https://www.projectnoah.org/spottings/135616016 and https://www.projectnoah.org/spottings/21883009 and https://upload.wikimedia.org/wikipedia/commons/a/af/Ceroplastes_cirripediformis.jpg and https://upload.wikimedia.org/wikipedia/commons/3/30/Red_lerps_austrochardia_acaciae.jpg) - is achieved by means of secretion.


The body-parts secreted - '3-D printed', as it were, by glands - consist mainly of various organic compounds (https://www.perplexity.ai/search/what-is-the-overall-term-for-m-vzBxp5QiQsiuxJqs.GQVnQ), including both

These secreted structures, which can be substantial relative to body size, are non-living, even though they form part of a living body.

It is true that important components - particularly the exoskeleton and wing-membranes - of the body in metabolous arthropods consist of dead tissue. However, there is a categorical distinction between once-living (i.e. metabolising, containing DNA, and undergoing cell-division), now-dead materials on one hand, and materials that have never been alive on the other.

The relevant body-parts of secromorphic insects, particularly the waxy filaments, shields, and lattices secreted by sap-sucking sternorrhynchan hemipterans (https://en.wikipedia.org/wiki/Sternorrhyncha), fall into the latter category.

Everyone knows that the bodies of arthropods contain non-living components, particularly exoskeletons made of chitin (in some cases reinforced by calcium carbonate).

However, all chitinous body-parts are derived from cell-walls. In other words, they originate as living tissues that have then died and become indurated.

The crucial distinction is that the components produced in secromorphosis are not aptly described as dead. This is because - like secretions as a category - they were not metabolically active in the first place.

Within Hemiptera, the trend is for an inverse correlation between chitinousness and waxiness. Heteroptera rely on chitin, whereas Sternorrhyncha tend to have minimal exoskeletons, relying instead on wax. Achenorrhyncha are intermediate in this respect.

As far as I know,

  • all secrobolous insects are also hemimetabolous, i.e. they show hemimetamorphosis in the form of an ontogenetic series of nymphs culminating in an adult, and
  • most or all secrobolous insects fall within Hemiptera (https://en.wikipedia.org/wiki/Hemiptera).

It follows that most or all secrobolous insects are sap-suckers, foraging mainly on the fluid contents of phloem (https://en.wikipedia.org/wiki/Phloem).

This leads to a strange realisation: that hemipterans manifest two aspects of a rapid throughput of carbon and hydrogen, and to some extent oxygen.

Sap-sucking hemipterans take in much superfluous sugar as they filter dilute fluids for their content of nitrogen and mineral nutrients. As part of this process, they exude the energy-content of most of this sugar, whether as

There is a kind of congruence in the fact that sap-sucking hemipterans

  • take in large quantities of energy superfluous to metabolism, and
  • subsequently exude (3-D print, https://en.wikipedia.org/wiki/3D_printing) the energy-containing substances, in modified form, for various purposes.

In the case of most secrobolous hemipterans (belonging to a bewilderingly large number of families in two suborders and many superfamilies):
sugar in, wax out.

And wax can be so much more durable/imperishable than sugars - indeed, almost as durable as chitin in the case of small insects - that it can effectively constitute a large proportion of the body (albeit extraneous to the tissues, both living and dead).

In the past, most insects have been categorised as either holometabolous or hemimetabolous. With the realisation that many sternorrhynchan and some auchenorrhynchan hemipterans are secrobolous, how should woolly aphids, lerp psyllids, wax scalebugs, etc., be best categorised?

Relevant to this question is the observation that the waxy secretions are best-developed in nymphs in some clades of hemipterans, vs in adults in other clades. In some families, even the eggs are invested in waxy filaments (https://www.perplexity.ai/search/in-which-sternorrhynchan-and-a-SD3Y5dGdRjOM_qDIWNoKZw).

In extreme cases, an adult the size of a small fly (https://upload.wikimedia.org/wikipedia/commons/8/89/Bird_of_Paradise_Fly.jpg) may possess a waxy 'tail', consisting of filaments up to 7.5 cm long (https://www.inaturalist.org/taxa/706751-Callipappus-australis and https://www.perplexity.ai/search/which-sternorrhynchan-hemipter-b8qjNcwDQvOh4qos8rQxSQ).

Given that the secretions correspond incongruently to growth-stages, across the various clades of hemipterans, I would argue that the categorisation of certain taxa as secrobolous is more relevant/informative than their categorisation as hemimetabolous.

Here is a question corollary to this topic:
Does any insect secrete chitin, which is a polysaccharide, viz. a polymer of sugar (https://www.perplexity.ai/search/is-any-arthropod-known-to-secr-xA81XDKuT4ykAEVrVpQxaA)?


















Publicado el 09 de julio de 2024 a las 09:23 PM por milewski milewski | 14 comentarios | Deja un comentario

Is the Australian mole (Notoryctes) a supermole?

The marsupial mole (Notoryctes, https://en.wikipedia.org/wiki/Marsupial_mole and https://www.abc.net.au/news/2023-06-17/elusive-marsupial-mole-spotted-uluru-swims-in-sand/102482890 and https://books.google.com.au/books?hl=en&lr=&id=5IqhZoTEF10C&oi=fnd&pg=PA464&dq=Marsupial+mole&ots=KQKu9dlYtl&sig=6N4ZqycOmL5In2yGuKzJVJ7tIF8&redir_esc=y#v=onepage&q=Marsupial%20mole&f=false) superficially resembles placental moles, despite being unrelated to them.

This is one of the most striking examples known of evolutionary convergence (https://en.wikipedia.org/wiki/Convergent_evolution).

However, the marsupial mole does not merely combine the presence of a pouch with the disappearance of eyes and ears.

As research gradually uncovers the details about the only Australian mole, what is emerging is that this is more than a lookalike.

The marsupial mole may indeed be the quintessential mole. It not only matches, but possibly surpasses, the adaptive extremes shown by subterranean mammals on other continents.

The marsupial mole has a large, bare pad on the head (https://www.bbc.com/news/world-australia-68720246). This has not been studied, but appears to be a blunt instrument of subterranean locomotion.

Unlike other moles, the marsupial mole has fused vertebrae in the neck, which presumably allows great pressure to be placed on the head as a ramrod.

Typical moles (Talpidae, https://en.wikipedia.org/wiki/Talpidae) lack a burrowing organ on the head, instead having pointed muzzles as soft as those of shrews.

Golden moles (Chrysochloridae, https://en.wikipedia.org/wiki/Golden_mole), the moles of Africa, have a tough nose used as a wedge (https://afrotheria.net/golden-moles/photos.php). However, the bare pad is far too small to extend to the forehead.

If typical moles and golden moles are not as extremely adapted to butting through the earth as is the marsupial mole, this may be because they repeatedly commute along tunnels once they have constructed them.

The marsupial mole appears to have no open tunnels, instead forcing its way afresh through every centimetre of earth in the course of its locomotion (https://www.publish.csiro.au/am/AM13015).

In this sense, the marsupial mole may be the ultimate subterranean mammal.

A failure to construct tunnels explains why, unlike other moles, the marsupial mole does not make molehills.

The Namib golden mole (Eremitalpa, https://en.wikipedia.org/wiki/Grant%27s_golden_mole) also lacks molehills. However, it differs from the marsupial mole by depending partly on swimming through the relatively loose sand at the surface of dunes. They maintain their body temperatures, remain active and warm even under the snows of winter, and reproduce relatively rapidly.

The forefoot of the marsupial mole is extreme, since the claws form a vertical spade (https://www.abc.net.au/news/2024-04-07/-northern-marsupial-mole-kakarratul-sighted-/103662744).

Typical moles have different forefeet, essentially broad paws projecting sideways as if from the neck (https://www.sci.news/biology/european-moles-sand-08805.html and https://www.parchilazio.it/cammino_naturale_dei_parchi-schede-7288-animalisulcammino_la_talpa_europea and https://nature.guide/card.aspx?lang=en&id=579), and used for raking relatively crumbly soil sideways.

Whereas the claws of typical moles move beside the body, those of the marsupial mole cleave the sand downwards, in front of the body.

Golden moles have pick-like claws on digits number 2 and 3 of the forefoot, held horizontal instead of vertical.

The marsupial mole has similar claws in digits 2 and 3. However, it has an additional, particularly large claw on digit 4, which forms the main blade of the articulated spade.

Typical moles lack external ears, but retain internal ear bones capable of hearing low-pitched vibrations underground.

The marsupial mole is unique among moles, because its entire ear is degenerate. The extremely small size of its internal ear bones suggest that the marsupial mole is nearly deaf as well as blind (https://www.mdpi.com/2073-4425/14/11/2018 and https://www.pnas.org/doi/abs/10.1073/pnas.94.25.13754).

This contrasts with the golden moles, in some of which the size of the ear bones exceeds that of surface-dwelling mammals, proportional to body size.

The tail of the marsupial mole is odd, inviting further study. Its appearance suggests that the tail may be used as a prop, allowing extra pressure to be placed on the head and claws. If so, the use of the tail in digging is unprecedented among subterranean mammals. No-one has yet a found a way to observe the marsupial mole in action underground.

The marsupial mole differs in habitat from other moles. It is widespread in, and apparently restricted to, hummock grassland (https://www.anbg.gov.au/photo/vegetation/hummock-grasslands.html and https://www.publish.csiro.au/am/AM00115).

This is a peculiar type of 'desert' restricted to Australia, sandy and dry but vegetated (https://www.inaturalist.org/posts/58175-the-australian-empty-quarter-epitome-of-a-nutrient-desert#).

Failure of Europeans and domestic animals to exploit hummock grassland owes more to this land's extreme nutrient-poverty than its aridity (https://www.inaturalist.org/posts/58175-the-australian-empty-quarter-epitome-of-a-nutrient-desert).

This semi-desert is even less fertile than the Sahara, so that 20% of Australia remains deserted to this day, despite the availability of groundwater in boreholes.

The main cover consists of grasses (Triodia, https://en.wikipedia.org/wiki/Triodia_scariosa) more spiny, unpalatable, and flammable than any common grass on other continents.

Although sand is extensive on the other southern continents, no mole lives in vegetated sand under dry conditions far inland.

Typical moles are widespread in the Northern Hemisphere (https://people.wku.edu/charles.smith/faunmaps/Talpidae.htm). However, they depend on the organic, loamy soils of deciduous woodlands.

Golden moles in Africa extend to sandy substrates in coastal areas. However, they are absent from the only habitats comparable to that of the marsupial mole: the Kalahari in southern Africa (https://en.wikipedia.org/wiki/Kalahari_Desert), and sandy parts of the Sahel at the edge if the Sahara (https://en.wikipedia.org/wiki/Sahel).

There are no moles today in central and South America, although fossil moles related to armadillos have been excavated. The most mole-like species alive now is the lesser fairy armadillo (Chlamyphorus truncatus, https://www.inaturalist.org/taxa/47097-Chlamyphorus-truncatus), restricted to a small area of sandy soil in semi-arid Argentina (https://upload.wikimedia.org/wikipedia/commons/2/29/Lesser_Fairy_Armadillo_area.png).

What little is known of the diet of the marsupial mole suggests an unusual reliance on insect larvae (https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2011.00889.x). I suspect that the tropical species of marsupial mole (Notoryctes caurinus) may depend partly on the brood (eggs, larvae, pupae) of ants, which it raids by burrowing from one subterranean ant nest to another.

By comparison:

Subterranean mammals have to devote most of their food energy to the strenuous work of burrowing. However, they save energy when resting, because the underground environment has a comfortable temperature and a poor supply of oxygen.

In addition, protection from predators means that subterranean mammals do not need to devote much energy to reproduction.

The resting metabolism of golden moles and armadillos is even slower than that of most marsupials. However, further research may show that the reproduction of the marsupial mole is particularly slow.

If so, it is possible that the marsupial mole devotes less of its energy to offspring, and more of its energy to locomotion, than any other subterranean mammal. Typical moles are different, because they have a rich supply of earthworms in ventilated tunnels.

The marsupial mole stretches our concept of the genetic plasticity of marsupials. It may also be a 'supermole' in stretching adaptive limits beyond those of placental moles. The broad hard organs of its head and forefeet, and to a lesser degree hindfeet and tail, equip it to burrow afresh to each meal, despite the poor food to be found in a habitat lacking both nutrients and water.

Genetic constraints and geographical isolation therefore fail to explain the absence of other body forms (equivalent to bears, pigs, primates, otters, cats, and ruminants) in the indigenous fauna of Australia.

In particular, the lack of mole-rats in Australasia is unlikely to be an accident of history. All other continents (including central and South America) have rodents resembling gophers, derived from a total of eight families which have independently undergone reduction of eyes, ears, tails, and resting metabolic rates (https://www.jstor.org/stable/2096793).

However, the supply of edible tubers appears to be smaller in hummock grassland than in the Kalahari. Possibly, mole-rats failed to evolve in Australia because of a lack of suitable tubers as food.

Publicado el 09 de julio de 2024 a las 08:36 AM por milewski milewski | 16 comentarios | Deja un comentario

07 de julio de 2024

The ecological and biogeographical significance of Prodotiscus regulus, an anthropogenic addition to the avifauna of Cape Town, South Africa

@tonyrebelo @ludwig_muller @jeremygilmore @vynbos @lukedowney @carasylvia @moxcalvitiumtorgos @rion_c @johnnybirder @theoutdoorman102 @surfinbird @justinponder2505 @simontonge @nwatinyoka @richardgill @adamwelz @boerseun86 @luke_goddard @zroskoph @kristaoswald @gareth_bain @wikus_burger @wingate @joelradue @colin25 @lindeq @the_bush_fundi @gigilaidler @lindalakeside @manatok @christiaan_viljoen @ekmes @ianrijsdijk @markheystek

Prodotiscus regulus (https://www.inaturalist.org/taxa/17591-Prodotiscus-regulus) is

The aim of this Post is to explain how P. regulus has come to be the only species of bird in the Cape Floristic Region (https://en.wikipedia.org/wiki/Cape_Floristic_Region) that specialises dietarily on the exudates of sap-sucking hemipteran insects (https://tcimag.tcia.org/training/sap-sucking-insects-how-they-feed-and-the-damage-they-cause/).

Like all members of its family (https://www.sciencedirect.com/science/article/abs/pii/S1095643302001307#:~:text=Birds%20ate%20significantly%20more%20new,transit%20time%20of%20256%20min. and https://pubmed.ncbi.nlm.nih.gov/12160878/), P. regulus can digest wax (https://en.wikipedia.org/wiki/Wax), as a major source of metabolic energy.

This is remarkable, because wax is

Before European arrival, there was no niche for P. regulus in the southwestern part of South Africa.

This is mainly because

Exudates of sap-sucking hemipterans are mainly of two kinds, viz.

Europeans introduced several spp. of Acacia (https://en.wikipedia.org/wiki/Acacia) from Australia to the Cape Floristic Region.

These shrubs and trees have proven to be so ecologically vigorous in their new environment that they are regarded as invasive (https://www.cabidigitallibrary.org/doi/10.1079/9781800622197.0026).

Also introduced - albeit mainly inadvertently - from various parts of the world were several hemipterans capable of sucking the sap of these acacias (https://www.perplexity.ai/search/australian-spp-of-acacia-have-5WdSTOFwQHK06p4MSWQYiw and https://en.wikipedia.org/wiki/Icerya_purchasi).

Now, for the first time in and near Cape Town (https://en.wikipedia.org/wiki/Cape_Town), there was a plentiful source of sap-sucking hemipterans and their exudates, as potential food for arboreal birds indigenous to South Africa.

In the case of honeydew, the main indigenous bird that seems to have benefited is Zosterops, a genus observed elsewhere in Africa to forage side-by-side with P. regulus (Friedmann 1955, https://repository.si.edu/handle/10088/10101 and https://scholar.google.com/citations?user=62DqSSUAAAAJ&hl=en).

Zosterops (https://www.inaturalist.org/observations?place_id=6986&taxon_id=17439&view=species) is a small-bodied passerine with the odd combination of a short, thin beak and a brush-tipped tongue. This allows it to lap up the newly-provided honeydew, in addition to its original staple diet of fleshy fruit-pulp (and -juice) and insects (https://www.researchgate.net/publication/249439178_Summer_and_winter_diet_of_the_Cape_white-eye_Zosterops_pallidus_in_South_African_grassland#:~:text=...-,The%20Cape%20white%2Deye%20is%20described%20as%20a%20generalist%20feeder,their%20diet%20(Kopij%202004)%20.).

However, this hardly changed Zosterops biogeographically, because it had been present in the Cape Floristic Region in the first place.

In the case of the waxy exudates, the only indigenous birds that might benefit were Indicatoridae.

As many as three spp. of Indicator may have been indigenous to the Cape Floristic Region, viz.

However, this genus is adapted to take wax from the nests of Hymenoptera, not from the exudates of hemipterans. This preference may be explained partly by the fact that Indicator is larger-bodied than Prodotiscus (https://en.wikipedia.org/wiki/Honeyguide).

Instead, what seems to have happened is that a small-bodied species, viz. P. regulus, entered the Cape Floristic Region for the first time during the twentieth century. This spontaneous recruitment filled the newly-provided niche.

There was no competition between P. regulus and Zosterops, because

  • the former is hardly able to ingest honeydew, and
  • the latter is unable to digest wax.

Honeydew is not utilised by Indicatoridae, despite

The inutility of honeydew for Indicatoridae, including P. regulus, seems to be because they

What has arisen is something biogeographically remarkable, and overlooked by naturalists despite the avifauna of Cape Town, and the Cape Floristic Region, being intensively studied.

This is that

Publicado el 07 de julio de 2024 a las 03:45 AM por milewski milewski | 9 comentarios | Deja un comentario

04 de julio de 2024

A puzzling lack of honeydew-producing hemipteran insects in the Cape Floristic Region of South Africa

@tonyrebelo @jeremygilmore @ludwig_muller @rjpretor @psyllidhipster @wongun @fabienpiednoir @bnormark @nomolosx @vynbos @peterslingsby @erincpow

Honeydew (https://en.wikipedia.org/wiki/Honeydew_(secretion) and https://www.sciencedirect.com/science/article/abs/pii/B9780123741448001314) is produced by various families of sap-sucking hemipterans in the suborders

The main sternorrhynchan families involved are

(For auchenorrhynchan families see https://www.inaturalist.org/posts/96522-a-puzzling-lack-of-honeydew-producing-hemipteran-insects-in-the-cape-floristic-region-of-south-africa#activity_comment_ad4868eb-6860-4458-b914-3a0659762ec5.)

Honeydew-producing hemipterans are common and diverse in several ecosystems that are

  • dominated by evergreen, woody plants,
  • nutrient-poor (particularly w.r.t. phosphorus and zinc), and
  • prone to wildfire.

The following ecosystems are particularly relevant.

Boreal forest (https://en.wikipedia.org/wiki/Taiga):

The incidence of sap-sucking hemipterans is summarised in https://www.perplexity.ai/search/which-are-the-main-sap-sucking-EM7jj6ifR_y2Oe2cmqAO_Q.

Eucalypt-dominated vegetation in Australia:


Honeydew is so common in eucalypt-dominated vegetation that honeyeaters (Meliphagidae) often eat this substance in place of nectar (https://www.publish.csiro.au/mu/mu9800213).

Kwongan in Australia:



At least one family of honeydew-producing hemipterans, viz. Pseudococcidae, is noted for its diversity in the floristically-rich southwestern region of Western Australia (https://www.perplexity.ai/search/which-honeydew-producing-sap-s-4PdFXzbnSziooSPIbxUcYw and https://www.inaturalist.org/posts/96522-a-puzzling-lack-of-honeydew-producing-hemipteran-insects-in-the-cape-floristic-region-of-south-africa#activity_comment_4fdf2d80-eeb1-404c-9aac-4f7225c93fe9).

Cerrado in South America:



Now, the fynbos biome of South Africa is nutrient-poor and fire-prone (https://en.wikipedia.org/wiki/Fynbos and https://www.sciencedirect.com/science/article/pii/S0254629914002117).

Therefore, we might expect fynbos - and the Cape Floristic Region (https://en.wikipedia.org/wiki/Cape_Floristic_Region) in general - to feature honeydew-producing hemipterans.

However, I have found hardly any information on this in the literature (https://www.perplexity.ai/search/anoplolepis-tends-sap-sucking-tebUgY.xQMuD36uISyJYNg and https://www.perplexity.ai/search/in-southern-africa-which-indig-yHiltTzwTESZjCLocBN0aA and https://www.perplexity.ai/search/in-southern-africa-which-are-t-Yajw5J0hT0GAFWFTNu8Zug and https://www.perplexity.ai/search/is-there-any-literature-on-hon-BNXvvEnVQAS_Gi41Ja.GyA).

Nectariniidae (https://www.perplexity.ai/search/is-any-member-of-nectariniidae-AArpb.xdSre4mi7wy.IwnA) and Promeropidae (https://www.perplexity.ai/search/has-promerops-ever-been-record-WC3kBuvWSGCnV5Nz5jg6hw), common in fynbos, have not been recorded eating honeydew. In this way, they differ from their approximate ecological counterparts, viz. Meliphagidae, in Australia.

It may be relevant that European heathland, superficially similar to ericoid fynbos (https://en.wikipedia.org/wiki/Ericoid), also seems poorly-documented for honeydew-producing hemipterans (https://www.perplexity.ai/search/which-are-the-main-honeydew-pr-N0CYxtJtRMqg9Z9zB2sjRw).

This leaves us with the following question:

Is the dearth of information on honeydew-producing hemipterans in fynbos because of a gap in coverage, or does it reflect a real poverty, indicating some basic and poorly-understood aspect of the functions of the ecosystem?


The following are notes in the biogeography of various clades of honeydew-producing hemipterans.


In the Northern Hemisphere, Aphididae are a major family producing honeydew. In Australia, indigenous Aphididae are ecologically unimportant (https://academic.oup.com/aesa/article/96/2/107/27979). Here,their place is taken by Psyllidae and Pseudococcidae.

In New Zealand, the main indigenous sternorrhynchans that produce honeydew are Margarodidae, Coccidae, and Aphididae.









Publicado el 04 de julio de 2024 a las 09:54 AM por milewski milewski | 21 comentarios | Deja un comentario