INTRODUCTION
Australia and southern Africa are ecologically comparable.
Both landmasses possess a range of climates, from mediterranean (https://en.wikipedia.org/wiki/Mediterranean_climate) and adjacent arid to summer-rainfall tropical (https://en.wikipedia.org/wiki/Climate_of_Australia#:~:text=The%20largest%20part%20of%20Australia,varying%20between%20grasslands%20and%20desert. and https://en.wikipedia.org/wiki/Climate_of_South_Africa).
Furthermore, in both cases the substrates tend to be nutrient-poor, owing to profound weathering on a largely flat topography (https://pubmed.ncbi.nlm.nih.gov/17624961/ and https://www.researchgate.net/publication/6213166_Ecology_of_Australia_The_effects_of_nutrient-poor_soils_and_intense_fires).
In both Australia and southern Africa, there are many and various plants pollinated mainly by birds (https://www.tandfonline.com/doi/pdf/10.1080/0028825X.1979.10432566#:~:text=The%20genera%20most%20frequently%20visited,insects%20as%20well%20as%20birds. and https://www.tandfonline.com/doi/abs/10.1080/0028825X.1979.10432566 and https://mdahlem.net/birds/plant/pollen.php and https://science.uct.ac.za/fitzpatrick/research-understanding-biodiversity-evolutionary-and-behavioural-ecology/bird-pollination-cape-floristic-region and https://naturesvalleytrust.co.za/wp-content/uploads/2023/07/Whitehead-K.-2018.pdf and https://www.sciencedirect.com/science/article/abs/pii/S0367253006000259 and https://www.jstor.org/stable/43234070).
On both landmasses, the flowers/inflorescences in question tend to be bright-hued, bearing copious nectar deep within a structure that makes it adaptive for nectarivorous passerine birds to have long, curved beaks.
AIMS
It is widely believed that certain Meliphagidae (https://en.wikipedia.org/wiki/Honeyeater) in Australia and certain Nectariniidae (https://en.wikipedia.org/wiki/Sunbird) in southern Africa show evolutionary convergence (https://en.wikipedia.org/wiki/Convergent_evolution), as part of an adaptive syndrome of mutualism with ornithophilous plants (https://en.wikipedia.org/wiki/Ornithophily).
The aim of this Post is to test evolutionary convergence in the case of meliphagids in Australia vs nectariniids in southern Africa.
NON-CONVERGENCES EMERGING FROM MY INTERCONTINENTAL COMPARISON OF MELIPHAGIDS WITH NECTARINIIDS
The following scrutiny undermines the 'textbook' interpretation.
Meliphagids, which are broadly associated with ornithophily, have undergone an extreme evolutionary radiation in Australia. However, my main finding is that it is the differences between meliphagids and nectariniids that emerge as more significant than the similarities.
The failure of evolutionary convergence in this case might have been anticipated by the observation that meliphagids tend to differ from nectariniids in having relatively large bodies and relatively short beaks. However, the biological disparities are deep and wide, and most remain even when the closest intercontinental counterparts are carefully compared.
The main intercontinental differences are as follows.
Firstly, the tongues are remarkably different.
In meliphagids, the tongue is fairly simple except for its brush-like tip (https://www.merriam-webster.com/dictionary/fimbriated and https://www.perplexity.ai/search/does-the-morphology-of-the-ton-dWPr2lh8Qi.prkVX4Uv7Jg and https://www.perplexity.ai/search/can-the-tongue-of-any-nectarin-M7OaIr9IR86NcZp.ZVFZjA).
By contrast, in nectariniids the tongue is odd even among nectarivorous birds (https://www.biorxiv.org/content/10.1101/2024.05.14.594085v1.full.pdf). This is because it operates by means of suction, as opposed to capillarity, or pressure exerted by the closure of the beak.
In other words, the tongue of nectariniids serves as a drinking straw (https://en.wikipedia.org/wiki/Drinking_straw), the main complication being the distal bifurcation of the straw.
Secondly, plumage and colouration differ according to the following syndrome:
Thirdly, no meliphagid builds a 'dome' nest. By contrast, all nectariniids build nests protected and hidden by a roof. The closest convergence is achieved by e.g. Lichmera indistincta, the nest of which is pouch-like - but still open at the top.
Fourthly, 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.
CLOSEST INTERCONTINENTAL COUNTERPARTS
Please note: in all cases the difference remains that
(My values for body length and body mass refer to adult females.)
The meliphagid Sugomel nigrum (https://www.inaturalist.org/taxa/367631-Sugomel-nigrum, body length 11 cm, body mass 9.5 g) is fairly closely matched with the nectariniid Cinnyris fuscus (https://www.inaturalist.org/taxa/145189-Cinnyris-fuscus and https://thebdi.org/2024/06/04/dusky-sunbird-cinnyris-fuscus/, body length 10 cm, body mass ?8 g).
In both cases,
Sugomel nigrum is associated mainly with Myoporaceae (https://www.inaturalist.org/observations?subview=map&taxon_id=136365&view=species). The nectariniid is instead associated mainly with Asphodelaceae (https://www.inaturalist.org/observations?place_id=113055&subview=map&taxon_id=71400&view=species and https://www.naturepl.com/stock-photo-dusky-sunbird-cinnyris-fuscus-feeding-on-the-nectar-of-quiver-tree-nature-image01596050.html and https://www.inaturalist.org/observations/224213747 and https://www.inaturalist.org/observations/55666885).
The similarity in colouration is greatest when males of the nectariniid are in non-breeding plumage (https://www.inaturalist.org/posts/98889-failure-of-evolutionary-convergence-in-nectarivorous-birds-between-australia-meliphagidae-and-southern-africa-nectariniidae#activity_comment_68c95b95-0846-4b9d-85ab-c2631edd7749).
However, the following differences remain:
The meliphagid Acanthorhynchus superciliosus (https://www.inaturalist.org/taxa/12237-Acanthorhynchus-superciliosus, female length 14 cm, body mass 9 g) is somewhat similar to the nectariniid Anthobaphes violacea (https://www.inaturalist.org/taxa/145130-Anthobaphes-violacea, female length 12 cm, body mass ?7-8 g).
In both cases,
However, differences remains in
Myzomela sanguinolenta (https://www.inaturalist.org/taxa/12443-Myzomela-sanguinolenta, body length 10 cm, body mass 8 g) is fairly similar to Hedydipna collaris (https://www.inaturalist.org/taxa/145122-Hedydipna-collaris, body length 10 cm, body mass 8 g).
The meliphagid actually exceeds the nectariniid in sexually dimorphism in colouration.
Furthermore, both spp.
However,
The intercontinental difference in the nests - in size as well as shape - is illustrated in:
The meliphagid Myzomela obscura (https://www.inaturalist.org/taxa/12376-Myzomela-obscura, body length 13 cm, body mass ? g) is a counterpart for the nectarinid Cyanomitra olivacea (https://www.inaturalist.org/taxa/145136-Cyanomitra-olivacea, body length 13 cm, body mass 9 g).
Both forms
However,
Finally:
Cinnyris frenatus (https://www.inaturalist.org/taxa/1504995-Cinnyris-frenatus, body length 10 cm, body mass ?8 g) of tropical northeasternmost Australia is extremely similar to Cinnyris venustus (https://www.inaturalist.org/taxa/145188-Cinnyris-venustus, body length 10 cm, body mass 7 g) of northeasternmost southern Africa.
Both spp. are equatorial to tropical. The colouration is similar, including the sexual difference. (Is the Australian species the less sexually dimorphic in colouration?)
This, the closest matching of all, does not represent much evolutionary convergence. This is because
PHYLOGENETIC CONSTRAINTS?
The intercontinental differences pointed out here cannot be explained by means of phylogenetic constraints and the geographical isolation of Australia.
Among meliphagids, the genus most closely approaching iridescence is Myzomela. However, the beak in Myzomela is relatively short, reflecting a relatively generalised diet, lacking any ornithophilous specialisation.
tongue
https://sora.unm.edu/sites/default/files/journals/condor/v073n04/p0485-p0486.pdf https://www.inaturalist.org/taxa/979744-Kurochkinegramma-hypogrammicum
In general, the norm in meliphagids is relatively large-bodied and short-beaked, whereas the norm in nectariniids is small-bodied and long-beaked.
This is partly because:
Meliphagids have not reached southern Africa, but the converse does not apply. Nectariniids, although originating in Africa/Asia, have in fact reached Australasia - where they have failed to undergo evolutionary radiation.
The form of the nest is not 'genetically fixed' in meliphagids. One species, viz. Ramsayornis modestus (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).
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).
תגובות
https://onlinelibrary.wiley.com/doi/abs/10.1002/jmor.21513
https://www.perplexity.ai/search/describe-the-mechanism-whereby-XKc5Q4GJS.O9qT7_2fMR2g
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497234/
https://www.perplexity.ai/search/describe-the-mechanism-whereby-XKc5Q4GJS.O9qT7_2fMR2g
Lichmera indistincta:
https://besjournals.onlinelibrary.wiley.com/doi/full/10.1002/2688-8319.12262
https://www.researchgate.net/publication/371046295_Observations_of_nectarivorous_birds_and_potential_biological_control_agents_in_berry_orchards
https://www.perplexity.ai/search/describe-the-tongue-of-lichmer-BzCqnntsT0uxLdzgJoNHog
Paton and Collins (1989):
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1442-9993.1989.tb01457.x
https://link.springer.com/article/10.1007/BF00985098
https://www.aavac.com.au/files/2000-17.pdf
https://www.perplexity.ai/search/has-any-member-of-the-nectarin-0iY88OrKSKO5C0VQBB2V4A
Pizzey G (1980) A field guide to the birds of Australia, pages 356-357, re Cinnyris frenatus:
"Many spiders are eaten,,,takes quite large spiders, dismembering them while hovering before their webs".
https://www.perplexity.ai/search/do-any-nectariniids-in-africa-q8meL8wTQMuCpRG1SKagnQ
Lichmera indistincta
https://www.inaturalist.org/taxa/12526-Lichmera-indistincta
body length ?13 cm
body mass 9 g
https://www.perplexity.ai/search/in-which-nectariniidae-is-red-XR3BUNGtSp.ShSoTe8aehA
SUGOMEL NIGRUM (Australia) VS CINNYRIS FUSCUS (southern Africa)
When males are in breeding plumage, there is no confusion between Sugomel nigrum of semi-arid Australia and its closest counterpart, Cinnyris fuscus of semi-arid South Africa and Namibia:
Sugomel nigrum
https://www.graemechapman.com.au/library/viewphotos.php?c=245
https://www.inaturalist.org/observations/237940313
https://upload.wikimedia.org/wikipedia/commons/4/42/Black_Honeyeater.jpg
https://australian.museum/learn/animals/birds/black-honeyeater/
https://canberrabirds.org.au/birds/black-honeyeater/
https://ebird.org/species/blahon1
https://laurieross.com.au/border_galleries/honeyeaters/#
Cinnyris fuscus
https://www.biodiversityexplorer.info/birds/nectariniidae/cinnyris_fuscus.htm
https://www.inaturalist.org/observations/115567236
https://www.inaturalist.org/observations/199000215
https://www.inaturalist.org/observations/200918314
https://www.inaturalist.org/observations/70275289
https://www.inaturalist.org/observations/57960712
https://www.inaturalist.org/observations/18880535
However, males in non-breeding condition of C. fuscus have colouration similar to that of S. nigrum, as follows:
Sugomel nigrum
https://www.inaturalist.org/observations/79927782
https://www.inaturalist.org/observations/46897981
https://www.inaturalist.org/observations/46897118
https://www.inaturalist.org/observations/31659153
https://www.inaturalist.org/observations/26662712
https://www.inaturalist.org/observations/228703843
https://www.inaturalist.org/observations/204661748
https://www.inaturalist.org/observations/180862834
https://www.inaturalist.org/observations/180862829
Cinnyris fuscus
https://www.inaturalist.org/observations/218956668
https://www.inaturalist.org/observations/151574550
https://www.inaturalist.org/observations/237617079
https://www.inaturalist.org/observations/229807463
https://www.inaturalist.org/observations/228212986
https://www.inaturalist.org/observations/203613613
https://www.inaturalist.org/observations/151359608
https://www.inaturalist.org/observations/149976351
https://www.inaturalist.org/observations/27908295
https://www.inaturalist.org/observations/11030851
In terms of adaptive colouration, 'pied' patterns are particularly conspicuous at distance, owing to the bold contrast between dark and pale (black and white).
The following show that males of Sugomel nigrum qualify as pied, owing to the crisp contrast between dark and the white on the flanks just anterior to the folded wings:
https://www.inaturalist.org/observations/198543908
https://www.inaturalist.org/observations/193836228
https://www.inaturalist.org/observations/186014420
https://www.inaturalist.org/observations/185534986
https://www.inaturalist.org/observations/177488552
https://www.inaturalist.org/observations/168942733
https://www.inaturalist.org/observations/130890592
The following show that males of Cinnyris fuscus, despite their similarity to S. nigrum, do not qualify as pied:
https://www.inaturalist.org/observations/226248388
https://www.inaturalist.org/observations/173962897
https://www.inaturalist.org/observations/4299736
https://www.buckhambirding.co.za/dusky-sunbird-cinnyris-fuscus/
https://naturalselection.travel/wp-content/uploads/2019/06/19Kwessi-Dune-Lodge-Dusky-sunbird.jpg
https://www.inaturalist.org/observations/196432459
https://geoffpark.wordpress.com/2019/03/09/from-certhionyx-to-sugomel/
http://stellenboschwriters.com/Stellenbirds/dusky.html
https://africawild-forum.com/viewtopic.php?t=8081&start=1420
https://www.inaturalist.org/observations/229597257
https://www.sciencedirect.com/science/article/pii/S0254629909002701
https://royalsocietypublishing.org/doi/10.1098/rsbl.2019.0349
https://tytotony.blogspot.com/2010/11/brown-backed-honeyeaters-in-your-face.html
https://www.lirralirra.com/brown-backed-honeyeaters-and-crocodiles/
https://www.flickr.com/photos/lou1003/19965606946
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