When devils and thylacines went extinct

17 01 2018

devil-thylacine-extinctWe’ve just published an analysis of new radiocarbon dates showing that thylacines (Tasmanian ‘tigers’, Thylacinus cynocephalus) and Tasmanian devils (Sarcophilus harrisi) went extinct on the Australian mainland at the same time — some 3200 years ago.

For many years, we’ve been uncertain about when thylacines and devils went extinct in mainland Australia (of course, devils are still in Tasmania, and thylacines went extinct there in the 1930s) — a recent age for the devil extinction (500 years before present) has recently been shown to be unreliable. The next youngest reliable devil fossil is 25000 years old.

So, knowing when both species went extinct is essential to be able to determine the drivers of these extinctions, and why they survived in Tasmania. If the two extinctions on the mainland happened at the same time, this would support the hypothesis that a common driver (or set of drivers) caused both species to go extinct. Read the rest of this entry »


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Categories : Australia, decline, extinction, palaeo-ecology, population dynamics

Cartoon guide to biodiversity loss XLV

6 12 2017

The last set of biodiversity cartoons for 2017. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Categories : Australia, biowealth, cartoon, conservation, environmental policy

You know you’re screwed when the insects disappear

31 10 2017

dead cicadaLast Friday, ABC 891 here in Adelaide asked me to comment on a conservation paper doing the news rounds last week. While it has been covered extensively in the media (e.g., The Guardian, CNN, and Science), I think it’s probably going to be one of those things that people unfortunately start to forget right away. But this is decidedly something that no one should be forgetting.

While you can listen to me chat about this with the lovely Sonya Feldhoff on the ABC (I start chin-wagging around the 14:30 mark), I thought it prudent to remind CB.com readers just how devastatingly important this study is.

While anyone with a modicum of conservation science under her belt will know that the Earth’s biodiversity is not doing well, the true extent of the ecological tragedy unfolding before our very eyes really came home to us back in 2014 with the publication of WWF’s Living Planet Report. According to a meta-analysis of 10,380 population trends from over 3000 species of birds, reptiles, amphibians, mammals, and fish, the report concluded that the Earth has lost over 50% of the individuals in vertebrate populations since 1970. Subsequent revisions (and more population trends from more species) place the decline at over 60% by 2020 (that’s only a little over two years away). You can also listen to me speak about this on another radio show.

If that little bit of pleasant news didn’t make the pit of your stomach gurgle and a cold sweat break out on the back of your neck, you’re probably not human. But hang on, boys and girls — it gets so much worse! The publication in PLoS One on 18 October about Germany’s insect declines might be enough to tip you over the edge and into the crevasse of mental instability.  Read the rest of this entry »


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Categories : anthropocene, biodiversity, community ecology, conservation, conservation ecology, extinction

Cartoon guide to biodiversity loss XLIV

9 10 2017

Here’s another set of biodiversity cartoons to make you giggle, groan, and contemplate the Anthropocene extinction crisis. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Categories : Australia, biowealth, cartoon, conservation, environmental policy

Four decades of fragmentation

27 09 2017

fragmented

I’ve recently read perhaps the most comprehensive treatise of forest fragmentation research ever compiled, and I personally view this rather readable and succinct review by Bill Laurance and colleagues as something every ecology and conservation student should read.

The ‘Biological Dynamics of Forest Fragments Project‘ (BDFFP) is unquestionably one of the most important landscape-scale experiments ever conceived and implemented, now having run 38 years since its inception in 1979. Indeed, it was way ahead of its time.

Experimental studies in ecology are comparatively rare, namely because it is difficult, expensive, and challenging in the extreme to manipulate entire ecosystems to test specific hypotheses relating to the response of biodiversity to environmental change. Thus, we ecologists tend to rely more on mensurative designs that use existing variation in the landscape (or over time) to infer mechanisms of community change. Of course, such experiments have to be large to be meaningful, which is one reason why the 1000 km2 BDFFP has been so successful as the gold standard for determining the effects of forest fragmentation on biodiversity.

And successful it has been. A quick search for ‘BDFFP’ in the Web of Knowledge database identifies > 40 peer-reviewed articles and a slew of books and book chapters arising from the project, some of which are highly cited classics in conservation ecology (e.g., doi:10.1046/j.1523-1739.2002.01025.x cited > 900 times; doi:10.1073/pnas.2336195100 cited > 200 times; doi:10.1016/j.biocon.2010.09.021 cited > 400 times; and doi:10.1111/j.1461-0248.2009.01294.x cited nearly 600 times). In fact, if we are to claim any ecological ‘laws’ at all, our understanding of fragmentation on biodiversity could be labelled as one of the few, thanks principally to the BDFFP. Read the rest of this entry »


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Categories : Allee effect, Amazon, anthropocene, biodiversity, biowealth, carbon, climate change, community ecology, connectivity, conservation, conservation biology, conservation ecology, decline, deforestation, demography, development, drought, ecosystem, ecosystem function, endemic, endemism, environmental policy, exploitation, extinction, extinction debt, fire, flood, fragmentation, habitat loss, invasive species, logging, management, metapopulation, monitoring, population dynamics, population viability analysis, protected area, recovery, research, reserve, South America, tropical

Cartoon guide to biodiversity loss XLIII

12 08 2017

I’m travelling again, so here’s another set of fishy cartoons to appeal to your sense of morbid fascination with biodiversity loss in the sea. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Categories : cartoon, conservation, environmental policy, marine, science

It’s not all about temperature for corals

31 05 2017

CB_ClimateChange6_Photo

Three of the coral species studied by Muir (2): (a) Acropora pichoni: Pohnpei Island, Pacific Ocean — deep-water species/IUCN ‘Near threatened’; (b) Acropora divaricate: Maldives, Indian ocean — mid-water species/IUCN ‘Near threatened’; and (c) Acropora gemmifera: Orpheus Island, Australia — shallow-water species/IUCN ‘Least Concern’. The IUCN states that the 3 species are vulnerable to climate change (acidification, temperature extremes) and demographic booms of the invading predator, the crown-of-thorns starfish Acanthaster planci. Photos courtesy of Paul Muir.

Global warming of the atmosphere and the oceans is modifying the distribution of many plants and animals. However, marine species are bound to face non-thermal barriers that might preclude their dispersal over wide stretches of the sea. Sunlight is one of those invisible obstacles for corals from the Indian and Pacific Oceans.

If we were offered a sumptuous job overseas, our professional success in an unknown place could be limited by factors like cultural or linguistic differences that have nothing to do with our work experience or expertise. If we translate this situation into biodiversity terms, one of the best-documented effects of global warming is the gradual dispersal of species tracking their native temperatures from the tropics to the poles (1). However, as dispersal progresses, many species encounter environmental barriers that are not physical (e.g., a high mountain or a wide river), and whose magnitude could be unrelated to ambient temperatures. Such invisible obstacles can prevent the establishment of pioneer populations away from the source.

Corals are ideal organisms to study this phenomenon because their life cycle is tightly geared to multiple environmental drivers (see ReefBase: Global Information System for Coral Reefs). Indeed, the growth of a coral’s exoskeleton relies on symbiotic zooxanthellae (see video and presentation), a kind of microscopic algae (Dinoflagellata) whose photosynthetic activity is regulated by sea temperature, photoperiod and dissolved calcium in the form of aragonite, among other factors.

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Categories : Australia, bioclimatic envelope, biodiversity, biogeography, climate change, climate shift, conservation, coral reefs, ecology, extinction, invasive species, ocean, research, tropical

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