INTERCONTINENTAL SIMILARITY IN LACK OF LERP/MANNA/EXTRAFLORAL NECTAR IN DIETS
Meliphagids tend to eat honeydew/lerp/manna/extrafloral nectar as well as floral nectar (https://www.publish.csiro.au/mu/pdf/mu9800213#:~:text=Manna%2C%20honeydew%20and%20lerp%20have,of%20these%20resources%20and%20nectar. and https://www.tandfonline.com/doi/abs/10.1080/01584197.1980.11799277).
By contrast, nectariniids have not been recorded eating these alternative sugary exudates. The only exception of which I am aware is the ostensible eating of the sap of Elaeis guineensis (https://en.wikipedia.org/wiki/Elaeis_guineensis) by Cinnyris coccinigastrus (https://www.inaturalist.org/taxa/145182-Cinnyris-coccinigastrus), which may be anthropogenic.
I have not found any records of the eating of lerp/manna/extrafloral nectar in the meliphagids examined in this Post. This, as far as it goes, supports the notion of evolutionary convergence.
DISCUSSION
The above information shows a pattern of 'so near and yet so far'. There seems, at first sight, to be evolutionary convergence between certain meliphagids in Australia and certain nectariniids in southern Africa. However, closer scrutiny shows significant disparities in form and function.
There are two main ways of interpreting these disparities. Either the environments on the two landmasses are different enough that the adaptive outcomes (by means of natural selection) are also different, or convergence has been constrained by shortcomings in the ancestors.
In turn, the shortcomings were owing either to phylogenetic constraints or to geographical barriers to recruitment of suitable ancestors.
It is tempting to invoke the longstanding isolation of Australia, in explanation of the fact that a single family, viz. Meliphagidae, has undergone major adaptive radiation to a degree unrivalled by any avian family in southern Africa.
PHYLOGENETIC CONSTRAINTS?
The intercontinental differences pointed out here cannot be explained by means of phylogenetic constraints and the geographical isolation of Australia. This is because meliphagids show much adaptive versatility in relevant ways, including
Iridescence is known in at least one species of meliphagid (https://en.wikipedia.org/wiki/T%C5%AB%C4%AB and https://www.inaturalist.org/taxa/12580-Prosthemadera-novaeseelandiae). Therefore, the failure of all the members of this family examined in this Post to develop iridescence is unlikely to be an accident of evolutionary history. It is instead likely to be adaptive in some poorly-understood way.
By a similar token, a brush-tipped, not tubular, tongue is known in at least one species of nectariniid (https://sora.unm.edu/sites/default/files/journals/condor/v073n04/p0485-p0486.pdf and https://www.inaturalist.org/taxa/979744-Kurochkinegramma-hypogrammicum).
One species of meliphagid (https://www.inaturalist.org/taxa/12364-Ramsayornis-modestus) does actually build a nest similar to that of nectariniids (https://www.perplexity.ai/search/does-the-brown-backed-honeyeat-Owk0Fg1ySme.S4UJwWfsEA). This is particularly significant because the other species in the same genus builds a cup-shaped nest, typical of meliphagids.
Again: the failure of all the members of this family examined in this Post to build dome nests is unlikely to be an accident of evolutionary history. It is instead likely to be adaptive, and the relative paucity of certain predators on the 'island continent' is a possible factor.
Also relevant to the question of phylogenetic constraints is the fact that nectariniids have in fact reached Australia. Indeed, several genera may have reached what is now the Australian mainland, when there was a broad land-bridge from what is now New Guinea. The failure of nectariniids to undergo evolutionary radiation across Australia indicates ecological unsuitability rather than an accident of history/phylogenetic constraints.
Further investigation is warranted of the possible difference between meliphagids and nectariniids in predation on relatively large and venomous spiders. My impression from the literature is that nectariniids are the family more resembling 'arachnophages', in the sense that they use their long beaks not only to probe flowers, but also to kill spiders safely (https://www.inaturalist.org/posts/98889-failure-of-evolutionary-convergence-in-nectarivorous-birds-between-australia-meliphagidae-and-southern-africa-nectariniidae#activity_comment_0590a394-7178-4d76-bec2-11bc68b0e569 and https://en.wikipedia.org/wiki/Black-bellied_sunbird).
Comentarios
MELANOCHARITIDAE
https://en.wikipedia.org/wiki/Melanocharitidae
https://www.inaturalist.org/observations?subview=map&taxon_id=12154&view=species
https://www.inaturalist.org/observations?subview=map&taxon_id=90421&view=species
DICAEIDAE
https://en.wikipedia.org/wiki/Flowerpecker
https://www.inaturalist.org/observations?subview=map&taxon_id=13375&view=species
https://www.inaturalist.org/observations?subview=map&taxon_id=13444&view=species
Relevance:
Short-beaked, but:
closely related to Nectariniidae
sexually dimorphic
domed nest
tubular tongue (https://www.perplexity.ai/search/in-dicaeidae-what-is-the-form-MCdpqVvBRyaychWluEnNGQ) but with brush- or feather-like tip (https://en.wikipedia.org/wiki/Flowerpecker#/media/File:FlowerpeckerTongue.svg and https://archive.org/details/tonguenestofcert3953rand/page/580/mode/2up)
https://en.wikipedia.org/wiki/Flowerpecker#/media/File:FlowerpeckerTongue.svg
https://howieswildlifeimages.com/2016/07/22/amethyst-iridescent-green-and-violet-in-aloes/
https://www.perplexity.ai/search/both-nectariniids-and-meliphag-PNCnaWktT2i5m6vijzAL5g
@tonyrebelo
The difference between meliphagids and nectariniids, in the form of the nest, cannot be explained by phylogenetic constraints.
This is because certain meliphagids do indeed build 'domed' nests, while by the same token certain nectariniids do indeed build cup-shaped nests.
This variation, within each family, suggests that there would have been convergence intercontinentally, were it the case that the environments were similar enough.
Among meliphagids, one species of Ramsayornis (https://en.wikipedia.org/wiki/Ramsayornis) builds a domed nest (https://www.inaturalist.org/observations/163630934 and https://www.graemechapman.com.au/library/viewphotos.php?c=244 and https://mdahlem.net/birds/18/barbrhon.php and https://www.inaturalist.org/observations/144837345).
Furthermore, this species, viz. Ramsayornis fasciatus, occurs widely in tropical Australia (https://www.inaturalist.org/taxa/12365-Ramsayornis-fasciatus).
Among nectariniids, certain spp. of Arachnothera (https://en.wikipedia.org/wiki/Little_spiderhunter) build cup-shaped nests (https://static1.squarespace.com/static/5c1a9e03f407b482a158da87/t/657ae7e52bd82f194d838663/1702553574118/Yellow-eared-Spiderhunter.pdf).
Malachite Sunbirds seem to like nesting over water ...
https://www.perplexity.ai/search/do-meliphagidae-exemplify-adap-03p2815WQUiq8KTRQKOquQ
https://en.wikipedia.org/wiki/Yellow-faced_honeyeater
https://www.aavac.com.au/files/2011-11.pdf
@tonyrebelo
In Australia, two clades of vertebrates digest pollen along with nectar. These are certain Loriini (https://en.wikipedia.org/wiki/Loriini and https://www.aavac.com.au/files/2011-11.pdf) and one species of Tarsipedidae (https://en.wikipedia.org/wiki/Honey_possum).
This raises the question of whether any species of Meliphagidae, Nectariniidae, or Promeropidae digests pollen to any significant extent and degree.
In southern Africa, it seems unlikely that pollen is significant nutritionally for either nectariniids (which have tubular tongues, specialised for sucking nectar rapidly and efficiently) or promeropids (the proportional length of the beaks of which probably exceeds that in any meliphagid).
However, it seems reasonable to expect at least one meliphagid to include pollen as a significant part of its diet.
This is because meliphagids a) have undergone an adaptive radiation far greater than that in nectariniids, b) have short beaks in many genera, and c) have brush-tipped tongues, potentially suitable for eating pollen as well as mopping liquid exudates.
However, I have yet to find any evidence for the consumption of pollen in meliphagids, in the sense of any analogy with Loriini or Tarsipedidae.
My interrogation of artificial intelligence on this topic produced misleading information (https://www.perplexity.ai/search/does-any-species-of-meliphagid-CXRnDDreT5Kj4qZJHBBBCg).
This failure to eat pollen - despite diversification in eating floral nectar, extrafloral nectar, honeydew, manna, and lerp - is one of the unremarked aspects of the natural history of meliphagids.
EATING OF HONEYDEW BY A NECTARINIID
Leptocoma is a genus of 6 spp. Leptocoma zeylonica, which occurs in India, sometimes visits open fields of crops, and takes honeydew exuded by leafhoppers (Kumar, Satish, 1995, Sugary exudate of sorghum Sorghum bicolor as food of large grey babbler Turdoides malcolmi (Sykes), purplerumped sunbird Nectarinia zeylonica (Linn.) and redvented bulbul Pycnonotus cafer (Linnaeus). Bombay Nat. Hist. Soc. 92(3): 421-422).
Leptocoma zeylonica pollinates the mangrove Bruguiera, Woodfordia (Lythraceae), Hamelia (Rubiaceae), and Sterculia (Sterculiaceae).
https://absa.asn.au/wp-content/uploads/2019/07/Little-Wattlebird.pdf
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