Spreading the Seeds; animals 'helping' plants

I was reading an intriguing story yesterday - which I'll get to shortly - which led me to think about animals being 'employed' by plants to distribute seeds. There are various ways of doing this, including by sticky burrs which cling to fur and feathers, eventually being dropped (or releasing the seed) some distance from the start of the journey. 

Bidgee Widgee burrs, Acaena novaezelandiae, Family Rosaceae, hitching a ride on my boot laces,
alpine zone, Kosciuszko National Park. They'd probably prefer a wombat or wallaby, but I'll do!
Daisies are another family to employ this strategy.

Australia has perhaps the richest ant fauna in the world, so it is unsurprising that plants from a wide range of Australian families have employed them to assist in distributing seeds. Obviously they don't want the ants to break the seeds up and eat them, and in fact the seeds are usually too hard for the ants to eat. Instead the plant attaches a nutritious temptation to the seed, which the ants haul off to the nest, detaching the seed when they get there and leaving it on the surface or in an underground garbage dump. This dry attachment is either an aril (if it derives from the seed attachment) or an elaiosome (a fatty body different from the aril), and is smaller than the seed. Ants have been observed carrying such seeds up to 75 metres from where they found them.

Discarded seeds surrounding an ant nest, near Alice Springs, central Australia.

But does it work? It certainly does!

Seedlings sprouting from ant nest, Great Sandy Desert, Western Australia.

Ants don't seem to pay much attention to colour, so these arils and elaiosomes tend to be pale in colour. However some acacias have colourful (especially red) arils, which are displayed high on the plant for birds to gather - again taking the seeds along with it.

Blackwood Wattle Acacia melanoxylon, pods, Namadgi NP, near Canberra.

Overall however the simplest and most effective strategy is to have the seeds eaten by a large mobile animal and discarded elsewhere, in droppings or perhaps as regurgitate. Energy is a very important resource - and temptation - for animals, which of course is why so many plants wrap their seeds in colourful, sugar-filled fruits, constructed from the wall of the fertilised ovary. The hard seed passes through the body, deposited sometimes many kilometres away. Here are some birds caught in the act!

Double-eyed Fig Parrot Cyclopsitta diophthalma eating figs (of course), Cairns Esplanade, Queensland.

Metallic Starlings Aplonis metallica eating palm fruit, Cairns Botanic Gardens, Queensland.

Silvereye Zosterops lateralis, with heath berries, Family Ericaceae (or Epacridaceae),
Australian National Botanic Gardens, Canberra.

Pied Currawong Strepera graculina eating Cotoneaster sp. berries, suburban Canberra.
These hedges (and related Pyrocantha spp.) are widely planted in older Canberra suburbs, and currawongs
are important distributors of the seeds into nearby nature reserves, where they are a serious weed hazard.

Male Mistletoebird Dicaeum hirundicum with mistletoe seed, Bundjalung NP, New South Wales north coast.
Mistletoebirds live almost exclusively on mistletoe berries, and are the major vector of the seeds.
It is a fascinating story, and will have its own post one day.

In rainforests in particular, birds and fruit bats are very important vectors of the whole forests' seeds - trees, lianas and shrubs. 

Rose-crowned Fruit Dove Ptilinopus regina in fig, Kakadu NP, Northern Territory.
Other key bird groups involved in distributing rainforest seeds in Australia include bowerbirds
and orioles (which include the figbirds).

Another important contributor is Australia's second-largest bird.

Southern Cassowary Casuarius casuarius, Atherton Tableland, northern Queensland.

We now know that the seeds of the Javan Ash Ryparosa kurrangii, a rainforest tree from north Queensland, germinate far better if they've passed through a cassowary. In fact, over 90% of seeds taken from cassowary droppings germinated, compared with only 4% of uneaten seeds. It has long been known that cassowaries are important vectors of rainforest seeds, but this adds another dimension to their value in the rainforest ecosystem. (The researchers also incidentally found that Javan Ash seeds have one of the highest levels of cyanogens ever recorded in a plant, but presumably the birds pass them through quickly enough and without breaking the surface of the seed, so that they are unaffected.)

In rainforests elsewhere in the world, other birds perform similar roles.

Yellow-throated (or Black-mandibled) Toucan Ramphastos ambiguus, with cecropia fruit,
Wild Sumaco Lodge, northern Ecuador.

Grass-green Tanager Chlorornis riefferii, Abra Patricia Lodge, northern Peru.

Red-crowned Barbet Psilopogon rafflesii, Bako NP, Sarawak.

Bats must never be underestimated however, despite doing their valuable work under cover of darkness.

Black Fruit Bats Pteropus alecto, Charters Towers, Queensland.
Big bats like this - with wing spans of more than a metre - travel many kilometres in a night,
visiting distant rainforest remnants. Smaller seeds are ingested, but even larger ones can be carried
for several minutes before being spat out.

They are not the only mammals to perform the task however.

Ecuadorian Squirrel Monkey Saimiri macrodon (or Saimiri sciureus macrodon), Yasuní NP, Ecuador.

Seedlings sprouting from elephant dropping, Kibale NP, Uganda.

Some plants have even secondarily 'invented' fruit by causing the stem immediately below the bare terminal seed to swell, turn red or black, and fill with sugars, for the same reason as other plants develop 'real' fruit.

Dwarf Ballart Exocarpos strictus.The red 'fruit' is the pedicel, or flower stem, the real fruit is the hard dark nut below it,
comprising a seed in a hard casing.

Mountain Plum Pine Podocarpus lawrencei, Namadgi NP near Canberra.
This is a conifer, so clearly cannot have true fruit (which, as explained earlier, must develop from a flower).
Again the pedicel is swollen, coloured and sweet, and the seed sits on top of it.

Which is pretty much the story - except that I mentioned at the start something I read which triggered this. It was a study conducted by Japanese ecologists which implied that at least one group of animals might have adopted a similar strategy to distribute their 'seeds' - which are really eggs. Stick insects, or phasmids, are poor distributors - many are flightless - but occur on many islands. 

Titan Stick Insect Acrophylla titan, Nowra, south coast NSW.
This one can grow to 25cm long.

Moreover, many species can reproduce parthogenetically - ie without mating. In this case all the hatchlings are female; if they mate both males and females result. The scientists presumably wondered about these two things, because they tried feeding eggs of three phasmid species to Brown-eared Bulbuls Hypsipetes amaurotis, a major phasmid predator in Japan. Up to 20% of the eggs survived, and some hatched, meaning that the birds could potentially be enabling the flightless insects to island-hop. Their next task is to compare the genetics of stick insects along known bird flight paths, to see if there is a correlation. A small thing, but surely much of life depends on a collation of small interesting things...

White-bellied Cuckooshrike Coracina papuensis with large (probably gravid female) phasmid, Nowra.
Did this bird do a favour to its lunch by sparing and spreading its eggs?

NEXT POSTING THURSDAY 14 JUNE

(And remember that you can get a reminder when the next post appears by putting your email address in the Follow by Email box in the top right of this screen.
And I'd love to receive your comments - it's easy and you don't need to sign in!)

When Movies Fail Basic Biogeography; does it matter?

It mattered to me when I was a boy, getting taken to Tarzan movies for the animals. (I was less keen on the mandatory quicksand scenes and Loyal Native Bearers falling off narrow cliff tracks.) But I would be inevitably infuriated by what were to me monumental gaffes, such as having the wrong elephants in Africa!! (On the other hand I was quite relaxed about the preposterous basic premise of the story, which says something about me.)

I can't say for certain if this is Johnny Weissmuller (the US Olympic swimmer turned
archetypal Tarzan) but I can say with authority that these are Indian Elephants!

My search for screen animals broadened when the family up the road got a telly in the 1950s (or maybe early 1960s), and I used to go up to watch Jungle Jim in black and white. My boyish fury was unabated. Unlike Tarzan it wasn't always clear where it was intended to be set, but it didn't matter much - the combination of animals was wrong!

Grant Withers, the original Jungle Jim.
The would-be man-eating lion seems to be asleep (or worse) but that wasn't my main concern.

Withers was in time supplanted by Johnny Weissmuller, looking for a life after Tarzan.
And the tiger supplanted the lion (though I recall it was pretty random). I gather the original comic book series
was based in South-East Asia (in which case a tick for the tiger) but it was not at all clear
where the TV series was supposed to be.

And of course every 'jungle' movie ever made, including Tarzan and the Jungle Jim series, whether set in Africa, Asia or South America, includes as an essential element of the sound track Australian Laughing Kookaburras, South American Screaming Pihas, and Asian Green Peafowl (peacocks).

Both the Screaming Piha Lipaugus vociferans, Sacha Lodge, Ecuador, above
and the Laughing Kookaburra Dacelo novaeguineae, Canberra, below,
would probably be most surprised to hear their own impressive and distinctive voices ringing
out above Tarzan's head, Wherever-he-is in Africa.

 

My interest in this aspect of entertainment was unexpectedly reawakened over the weekend, when we went to see the movie Tracks, based closely on the 1978 book by Robyn Davidson of her truly remarkable solo camel trek of some 2000km west from Alice Springs to the Indian Ocean. (To be honest I don't go to many movies, so I'm not about to set up as film critic, but I enjoyed this one, especially the landscapes, while not entirely seeing what it added to the book.)

But.... In a scene not from the book, whose significance evaded me entirely, a large python slips across the sleeping 'Davidson' deep in the western deserts.

Irrespective of the purpose of the scene (I'm sure it will be immediately obvious to you), there's a
very fundamental problem. Carpet Pythons Morelia spilota, which this undoubtedly is, do not occur
anywhere near the western deserts - indeed there are no large pythons at all in the vast sandy tracts.
You can see the scene briefly here, at the 1 minute 27 second mark; being technologically limited, and
unable to find a still of the scene, I photographed it from this promo on my computer screen, hence the poor quality!

(There was another little blip to upset the biologist too, albeit not biogeographical; a Euro is shot for food by an Aboriginal elder, but mysteriously turns into a female Red Kangaroo when dead! The Euro only appeared briefly, and I'd like to see it again, but I tend to trust myself on this. On the other hand if it was a make of car, say, they could get away with anything as far as I'm concerned!)

Another famous bioblunder I recall from way back - though at least I was at uni by then - was the inexplicable insertion of Brazilian Tapirs Tapirus terrestris into a scene at the start of the epic 2001: a space odyssey. The problem is that the scene was set in the early days of human evolution - quite rightly in Africa.

The black hairy ones are our ancestors - the tapirs (whose alternative name South American Tapir says
it all really) are... well who knows?!

I hardly expect cartoons to be scientifically rigorous, but still... I recall Antz, an animated movie (yes, about ants - I can't explain the 'z') from the late 1990s. All the soldiers were explicitly male!

As most of us could have told them, ALL useful members of an ant colony, most certainly including
the soldiers, are exclusively female.

One I didn't see was Lion King, but I have read about the opening scenes, featuring leafcutter ants above the savannah.

Oops, sorry - only in South America!

Another I didn't see was Jurassic Park, but acting on a tip-off I looked up the amber-trapped mosquito which carried the dinosaur DNA (and I'm not getting into that one here!).

Very nice, but the lovely plumed antennae tell us that it's a male -
and only female mozzies feed on blood. Males are staunch vegetarians.

Another I managed to miss was the apparently history-annihilating 300, featuring Persians versus Spartans. The Persians apparently brought 'war rhinos' to the party - interesting concept, though I'd be fascinated by the logistics of training and control. However the movie makers fell into the Tarzan trap, albeit in reverse.

This redoutable accoutrement has two horns; the only plausible Asian rhino has only one.
They were looking at pictures of either of the two African species...
(I had a lot of trouble tracking down a still of this one - I'm still not totally sure this is it.
If you know I'm wrong, please let me know. However I have read elsewhere that the
movie war rhinos do have two horns so the story stands.)

At a different level entirely, even the saccharine and very English Mary Poppins is culpable. The well-known earworm Spoonful of Sugar refers to a robin 'feathering his nest'. Given that it's set in and around London, one might reasonably expect a familiar European Robin Erithacus rubecula. One would in that case be disappointed and surprised.

Did they think no-one would notice it was an entirely unrelated and dissimilar American Robin Turdus migratorius?
(Or that it is apparently stuffed, but to be fair the film was made 50 years ago - this year in fact.)

And while we're on Mary Poppins, it seems the use of male gender in the line from the song above
wasn't used lightly. I'm no expert on North American birds, but I'm almost certain this pair comprises two males.
A very bold statement from Disney back in 1964!

Mary Poppins isn't the only classic under my scrutiny today either. Harry Potter's faithful female Snowy Owl Hedwig regularly went out for nocturnal excursions; unfortunately Snowies are almost wholly diurnal. Also it is unlikely that Harry's evil relatives would have been so disturbed by her hooting (she literally couldn't give a hoot), though they may have got a bit fed up with her squeaky screeches which didn't rate a mention.

And even the wonderful Finding Nemo got one important point bizarrely wrong. Why would you impose an American Pelican - Brown or Peruvian, I can't be certain, though it's a bit of mix really - onto the Australian east coast?? There are plenty of Australian Pelicans there who would have been happy to step in!

Nigel was never going to pass muster as an Australian Pelican, which is essentially black and white!

Even a couple of my favourite recreational authors have let me down on occasions. Peter Corris, in one of his historical ventures (I think it was Wimmera Gold) talked about 'the mulga' in western Victoria. Acacia aneura covers a large part of inland Australia - but the only mainland state where it isn't found is Victoria. And Paul Doherty, in his generally well-researched ancient Egyptian series, more than once dressed important people in jaguar skins; I'm pretty sure the Egyptians didn't ever make it to South America!

Does any of it matter? Well if it doesn't bother you, then of course it's not important to you. On the other hand if you saw a car model, or a clothing style, that you knew wasn't possible in that context, it may jar enough to make you question other things that you would otherwise trust, and generally spoil your enjoyment. That's how it is for me with regard to tigers in Africa or Carpet Pythons in the western deserts. And these days in particular, there's really no excuse, is there?

Any contributions anyone?

BACK ON THURSDAY