Paleobiogeography- quite a mouthful!

It has been a while since my last post, apologies!

To gain a full understanding of a certain behaviour, ecological process or species distribution it is essential to view them from different aspects. For instance, to understand the distribution of a species a Butterfly one would need to investigate metapopulation dynamics, abiotic factors, community ecology and biogeography.

Biogeography is the study of organisms or ecosystems through space and time; Paleobiogeography goes one step further and looks at the effects of plate tectonics as well. Paleobiogeography helps us understand why certain groups have their distributions-

Why are marsupials distributed in Australasia and the Americas?
Because South America, Australia and Antarctica were joined together in one continent and as the continents split, marsupials were left on each landmass though those on Antarctica died out as the continent headed southwards.

Mexican Mouse Opossum Marmosa mexicana- an American Marsupial.

Why is there relatively high endemism in the North Pacific compared to similar latitudes?
Because of Beringia, a refuge of tundra amongst the ice sheets and glaciers during the last ice age which allowed many species to survive whilst surrounding latitudes were uninhabitable.

Mckay's Bunting Plectrophenax hyperboreus- endemic to the Aleutian Islands.

Paleobiogeography can also explain some strange behaviours such as the migration of the Bar-headed Goose Anser indicus which is famous for its high altitude migration over the Himalayas between its wintering grounds on the Indian Subcontinent and the Steppes of Northern Asia. On the face of it, it appears strange and counter productive for a bird to risk the high altitude route over the mountains when many other birds travelling in the same direction choose to fly around the range. Bar-headed Geese have amazing adaptations to cope with the stress of the journey such as modified haemoglobin and breathing rates and a larger wing to weight ratio. 

Bar-headed Geese Anser indicus.

But these adaptations only explain how they overcome the Himalayas, not why. The answer could well lie with paleobiogeography. The Himalayas are a relatively new mountain range formed when the Indian Subcontinent ploughed into the rest of Asia about 70 mya. It is quite possible that the ancestors of the Geese wintered in the low-lying land in the area and slowly, as India crumpled the land upwards the Geese had to fly higher and higher each year until they reached the levels that they regularly migrate at now (around 21,600 ft).

This is just one extreme example of the benefits of understanding paleobiogeography. Hopefully over the next few weeks I'll get round to writing up two other examples of the importance of biogeography in the understanding of species distributions.

Hula Painted Frog has been rediscovered

It is always refreshing when there's a rediscovery and no more so then when it's an Amphibian which have been plagued by so many threats of late.

The story of the Hula Painted Frog Discoglossus nigriventer is a classic example of the destructive impact of man upon wetlands. The Hula Valley in Israel was once a thriving wetland and an important agricultural region. The area had several endemic vertebrates associated with it such as Acanthobrama hulensis, an endemic Carp and Tristramella intermedia, an endemic Cichlid as well as the Frog. Unfortunately the area was a major breeding ground for Mosquitoes and Malaria and in 1951 the Jewish National Fund began the drainage of the wetland which was completed by 1958. As a result populations of both fish quickly declined and were declared extinct.

What remains of the Hula Valley Wetlands

A small area was recreated however and became Israel's first nature reserve, despite this the area remained severely degraded and repeated searches failed to find any evidence of the frog and in 1996 it was offically declared extinct.

Until this year however when a single female was discovered on the 16th of November during a routine search and a second individual was found on the 29th. The population here must be tiny, but hopefully some serious conservation measures can now be implemented. There also remains the tantalising possibility that the species is hiding out somewhere in Lebanon following a possible sighting in 2000 in the Aammiq Marshes.

Below are some of the first pictures of the Frog by Sarig Gafny.

Speciation

Bit of a cop out this week, just forwarding you on to someone else's blog!


Some interesting thoughts on speciation by Ted Floyd can be found here:

http://blog.aba.org/2011/12/darwin-schoenberg-and-sibley-a-new-dawn-for-birding.html

A thoroughly good read!



Pygmy & Brown-headed Nuthatches (Tom Munson & Terence Brashear)

Spoon-billed Sandpipers

It has been an interesting few months for bird conservation. The first ever ex-situ breeding programme for the Critically Endangered Spoon-billed Sandpiper Eurynorhynchus pygmeus has begun here in the UK.

Dead Spoon-billed Sandpiper, Saemangeum, South Korea (Nial Moores)

The Spoon-billed Sandpiper breeds in the tundra of north-eastern Russia and winters in China and South East Asia. Its population has thought to have decreased by 88% since 2002 equating to a decline by 26% every year. The breeding population has been estimated at 120-200 pairs though this could well be optimistic. The problem is that the Sandpipers are plagued by problems from all areas. Stray dogs are a real threat on their breeding grounds and the loss of habitat and hunting pressure both in their wintering gounds and along stop-off routes through Korea and China.

As a result the first ever captive breeding programme has been set up by the Wildfowl and Wetlands Trust and Birds Russia at Silmbridge in the UK. The first 13 birds have been transported to the UK from Moscow Zoo where they have been raised for the past few months. 

These will be the first of several and their descendants will hopefully one day be returned to the wild. Before this can happen though the problems in the wild need to be sorted out.

Just about the cutest baby ever! Elena Lappo

 

Follow the SBS blog here: http://sbsproject.wordpress.com/2011/11/14/theyre-here/

Spoon-billed Sandpiper factsheet here: http://www.birdlife.org/datazone/speciesfactsheet.php?id=3060

WWT page here: http://www.wwt.org.uk/what-we-do/saving-wildlife/science-and-action/globally-threatened-species/spoonbilled-sandpiper/

Imperial Woodpecker- Lest we forget

The Imperial Woodpecker Campephilus imperialis is (or was!) the largest known species of Woodpecker at a whopping 56-60cm. It is (or was!) endemic to the Sierra Madre Occidental Mountains in northern Mexico. It is however now classed at Critically Endangered (possibly extinct) as there hasn't been a confirmed sighting since 1956.

It's an impressive bird with a jet black body, white wings and a white 'V' on the back and a call that apparently sounds like a toy trumpet. Both sexes are crested with the males' being blood red and the females' black. It's a close relative of the also ill fated Ivory-billed Woodpecker of the USA and Cuba.

Recently the Cornell Lab of Ornithology released the only known footage of Imperial Woodpeckers in a remote area of the Sierra Madre recorded by Dr William L. Rhein in the 50's.



Apparently it hasn't come to light before now as Rhein was embarrassed by the video quality! It's rather sobering to think that this may be the only footage ever taken of this amazing bird and that there may not be another opportunity ever again.

The thoughts of William Beebe spring to mind:

"The beauty and genius of a work of art may be reconceived, though its first material expression be destroyed; a vanished harmony may yet again inspire the composer; but when the last individual of a race of living beings breathes no more, another heaven and another Earth must pass before such a one can be again."

Imperial Woodpecker factsheet: http://www.birdlife.org/datazone/speciesfactsheet.php?id=718

Polyandry and Alternative Mating Tactics- Meet the Jacanas.

For my inaugural post I'd like to talk about Jacanas.

Jacanas are Charadiiformes and are therefore related to birds such as Sandpipers, Gulls and Plovers rather than Moorhens, which they superficially resemble in appearance and habits. There are 8 species spread around tropical and sub-tropical regions: Two in the Americas (Northern and Wattled); Three in Africa (African, Lesser and Madagascan); Two in Asia (Pheasant-tailed and Bronze-winged) and one in Australasia (Comb-crested). All species are found in wetland habitats, particularly those with floating vegetation where they can be seen walking on the lilypads feeding on small invertebrates whilst spreading their weight with their hugely elongated toes. These traits have earned them the colloquial name of Lily Trotters. 7 of the 8 are ornamented to certain degrees with combs, wattles or bright plumage, Sexes are similar however the female is always more brightly coloured and larger than the male. The one exception to this is the Lesser Jacana where the sexes are identical.

A Comb-crested Jacana taken by Hans & Judy Beste; Queensland, Australia.

Larger, more brightly coloured females are an unusual trait in nature, though there are several examples in a range of taxa from Phalarope to Pipefish. This trait is usually linked to male parental care and in the case of Jacanas it is the male that single-handedly incubates the eggs and raises the young, leaving the females to fight it out over the males. This has lead to polyandry being documented in several species such as the Northern Jacana. Polyandry is a breeding adaption in which females mate with more than one male and is analogous to the more usual polygyny where males mate with more than one female. While polyandry is much more common than previously thought in birds it is usually accompanied by social monogamy it is rare to find a system where the male takes complete control of the young.

This has given rise to the possibility of infanticide being carried out by female Jacanas. Observations described in a 1982 paper in Animal Behaviour seem to suggest just this going on in the Northern Jacana. A female was witnessed attacking a resident female's territory and driving her out followed by agitated distraction behaviour being employed by the male. Within one day the male's clutch had been destroyed, leaving the male free to remate again. Though it is important to point out that the destruction of the nest was not witnessed, however the paper does present strong evidence for infanticide.

Some great photos of Bronze-winged and Pheasant-tailed Jacanas can be seen here: http://www.pbase.com/peterericsson/jacanas

Emlen S. T. & Wrege P. H. (2004) Division of labour in parental care behaviour of a sex-role-reversed shorebird, the wattled jacana. Animal Behaviour 68: 847-855.

Stephens M. L. (1982) Mate takeover and possible infanticide by a female Northern jacana (Jacana spinosa) Animal Behaviour 30: 1253-1254.

Welcome

Hi Folks,

I've decided to delve into the murky world of blogging. I hope to cover a range of topics from recent (and not so recent) developments in Zoology, Ecology, Evolution and Conservation as well as Natural History and a bit of birding!

Enjoy!