Individuals a population to conserve make

28 11 2012
Unique in its genus, the saiga antelope inhabits the steppes and semi-desert environments in two sub-species split between Kazakhstan (Saiga tatarica tatarica, ~ 80% of the individuals) and Mongolia (Saiga tatarica mongolica). Locals hunt them for their meat and the (attributed) medicinal properties of male horns. Like many ungulates, the population is sensitive to winter severity and summer drought (which signal seasonal migrations of herds up to 1000 individuals). But illegal poaching has reduced the species from > 1 million in the 1970s to ~ 50000 currently (see RT video). The species has gone extinct in China and Ukraine, and has been IUCN “Critically Endangered” from 2002. The photo shows a male in The Centre for Wild Animals, Kalmykia, Russia (courtesy of Pavel Sorokin).

In a planet approaching 7 billion people, individual identity for most of us goes largely unnoticed by the rest. However, individuals are important because each can promote changes at different scales of social organisation, from families through to associations, suburbs and countries. This is not only true for the human species, but for any species (1).

It is less than two decades since many ecologists started pondering the ways of applying the understanding of how individuals behave to the conservation of species (2-9), which some now refer to as ‘conservation behaviour’ (10, 11). The nexus seems straightforward. The decisions a bear or a shrimp make daily to feed, mate, move or shelter (i.e., their behaviour) affect their fitness (survival + fertility). Therefore, the sum of those decisions across all individuals in a population or species matters to the core themes handled by conservation biology for ensuring long-term population viability (12), i.e., counteracting anthropogenic impacts, and (with the distinction introduced by Cawley, 13) reversing population decline and avoiding population extinction.

To use behaviour in conservation implies that we can modify the behaviour of individuals to their own benefit (and mostly, to the species’ benefit) or define behavioural metrics that can be used as indicators of population threats. A main research area dealing with behavioural modification is that of anti-predator training of captive individuals prior to re-introduction. Laden with nuances, those training programs have yielded contrasting results across species, and have only tested a few instances of ‘success’ after release into the wild (14). For example, captive black-tailed prairie dogs (Cynomys ludovicianus) exposed to stuffed hawks, caged ferrets and rattlesnakes had higher post-release survival than untrained individuals in the grasslands of the North American Great Plains (15). A clear example of a threat metric is aberrant behaviour triggered by hunting. Eleanor Milner-Gulland et al. (16) have reported a 46 % reduction in fertility rates in the saiga antelope (Saiga tatarica) in Russia from 1993-2002. This species forms harems consisting of one alpha male and 12 to 30 females. Local communities have long hunted this species, but illegal poaching for horned males from the early 1990s (17) ultimately led to harems with a female surplus (with an average sex ratio up to 100 females per male!). In them, only a few dominant females seem to reproduce because they engage in aggressive displays that dissuade other females from accessing the males. Read the rest of this entry »





The Biodiversity Club

11 10 2012

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species uses 5 quantitative criteria to allocate species to 9 categories of extinction risk. The criteria are based on ecological theory (1, 2), and are therefore subject to modification and critique. With pros and cons (3-6), and intrigues (7, 8), the list has established itself as an important tool for assessing the state of biodiversity globally and, more recently, regionally.

We all carry codes of some sort; that is, unique alphanumeric labels identifying our membership in a collectivity. Some of those codes (e.g., a videoclub customer number) make sense only locally, some do internationally (e.g., passport number). Species are also members of the club of biodiversity and, by virtue of our modern concern for their conservation, the status of many taxa has been allocated to alphanumeric categories under different rationales such as extinction risk or trading schemes (5, 9-13). Contradiction emerges when taxa might be threatened locally but not internationally, or vice versa.

In the journal Biological Conservation, a recent paper (14) has echoed the problem for the seagrass Zostera muelleri. This marine phanerogam occurs in Australia, New Zealand and Papua New Guinea, and is listed as “Least Concern” (LC) with “Stable” population trend by the IUCN. Matheson et al. (14) stated that such status neglects the “substantial loss” of seagrass habitats in New Zealand, and that the attribution of “prolific seed production” to the species reflects the IUCN assessment bias towards Australian populations. The IUCN Seagrass Red List Authority, Fred Short, responded (15) that IUCN species ratings indicate global status (i.e., not representative for individual countries) and that, based on available quantitative data and expert opinion, the declines of Z. muelleri are localised and offset by stable or expanding populations throughout its range. Read the rest of this entry »





Life, death and Linneaus

9 07 2011

Barry Brook (left) and Lian Pin Koh (right) attacking Fangliang He (centre). © CJA Bradshaw

I’m sitting in the Brisbane airport contemplating how best to describe the last week. If you’ve been following my tweets, you’ll know that I’ve been sequestered in a room with 8 other academics trying to figure out the best ways to estimate the severity of the Anthropocene extinction crisis. Seems like a pretty straight forward task. We know biodiversity in general isn’t doing so well thanks to the 7 billion Homo sapiens on the planet (hence, the Anthropo prefix) – the question though is: how bad?

I blogged back in March that a group of us were awarded a fully funded series of workshops to address that question by the Australian Centre for Ecological Synthesis and Analysis (a Terrestrial Ecosystem Research Network facility based at the University of Queensland), and so I am essentially updating you on the progress of the first workshop.

Before I summarise our achievements (and achieve, we did), I just want to describe the venue. Instead of our standard, boring, windowless room in some non-descript building on campus, ACEAS Director, Associate Professor Alison Specht, had the brilliant idea of putting us out away from it all on a beautiful nature-conservation estate on the north coast of New South Wales.

What a beautiful place – Linneaus Estate is a 111-ha property just a few kilometres north of Lennox Head (about 30 minutes by car south of Byron Bay) whose mission is to provide a sustainable living area (for a very lucky few) while protecting and restoring some pretty amazing coastal habitat along an otherwise well-developed bit of Australian coastline. And yes, it’s named after Carl Linnaeus. Read the rest of this entry »





Taxonomy in the clouds

4 07 2011

Another post (see previous here, here and here) by my aspiring science-communicator PhD student, Salvador Herrando-Pérez.

Taxonomy uses rigorous rules of nomenclature to classify living beings, so every known species has a given ‘name’ and ‘surname’. The revision of certain taxonomic groups (particularly through genetic analyses) is favouring the proliferation of nominally new species, often propelled by virtue of their charisma and conservation status.

In secondary school, most of my classmates associated the subject ‘Biology’ with unpronounceable Latin taxonomic names, with which all known living beings are branded — ‘Canis lupus’ reads the identity card of humanity’s best friend. When the Swedish monk Carl Linnaeus proposed such binomial nomenclature, he could hardly imagine that, two hundred years later, his terminology would underpin national and transnational budgets for species conservation. Taxonomic nomenclature allows the classification of species into clusters of the same kind (e.g., diatoms, amanitas, polychaetes, skinks), and the calculation of an indispensable figure for conservation purposes: how many species are there at a given location, range, country, continent, or the entire planet?

Traditionally, taxonomists described species by examining their (external and internal) morphological features, the widest consensus being that two individuals of different species could not hybridise. However, a practical objection to that thinking was that if, for instance, an ocean separated two leopard populations, ethics should prevent us from bringing them in contact only to check if they produce fertile offspring, hence justifying a common-species status. Genetics currently provides a sort of ‘remote check’.

New species, new names

Over the last three decades, the boom of genetics and the global modernisation of environmental policies have fostered alternative criteria to differentiate species, populations, and even individuals. As a result, experts have created a colourful lexicon to label management or conservation units or new taxonomical categories such as that of a subspecies1, e.g., Canis lupus dingo for the wild Australian dog (dingo). These changes have shaken the foundations of taxonomy because several definitions of species (biological, phylogenetic, evolutionary) are forced to live under the umbrella of a common nomenclature. Read the rest of this entry »





Species’ Ability to Forestall Extinction – AudioBoo

8 04 2011

Here’s a little interview I just did on the SAFE index with ABC AM:

Not a bad job, really.

And here’s another one from Radio New Zealand:

CJA Bradshaw





S.A.F.E. = Species Ability to Forestall Extinction

8 01 2011

Note: I’ve just rehashed this post (30/03/2011) because the paper is now available online (see comment stream). Stay tuned for the media release next week. – CJAB

I’ve been more or less underground for the last 3 weeks. It has been a wonderful break (mostly) from the normally hectic pace of academic life. Thanks for all those who remain despite the recent silence.

© Ezprezzo.com

But I’m back now with a post about a paper we’ve just had accepted in Frontiers in Ecology and Environment. In my opinion it’s a leap forward in how we measure relative threat risk among species, despite some criticism.

I’ve written in past posts about the ‘magic’ minimum number of individuals that should be in a population to reduce the chance of extinction from random events. The so-called ‘minimum viable population (MVP) size’ is basically the abundance of a (connected) population below which random events take over from factors causing sustained declines (Caughley’s distinction between the ‘declining’ and ‘small’ population paradigms).

Up until the last few years, the MVP size was considered to be a population- or species-specific value, and it required very detailed demographic, genetic and biogeographical data to estimate – not something that biologists tend to have at their fingertips for most high-risk species. However, several papers published by our group (Minimum viable population size and global extinction risk are unrelated, Minimum viable population size: a meta-analysis of 30 years of published estimates and Pragmatic population viability targets in a rapidly changing world) have shown that there is in fact little variation in this number among the best-studied species; both demographic and genetic data support a number of around 5000 to avoid crossing the deadly threshold.

Now the fourth paper in this series has just been accepted (sorry, no link yet, but I’ll let you all know as soon as it is available), and it was organised and led by Reuben Clements, and co-written by me, Barry Brook and Bill Laurance.

The idea is fairly simple and it somewhat amazes me that it hasn’t been implemented before. The SAFE (Species Ability to Forestall Extinction) index is simply the distance a population is (in terms of abundance) from its MVP. In the absence of a species-specific value, we used the 5000-individual threshold. Thus, Read the rest of this entry »





Humans 1, Environment 0

27 09 2010

© flickr.com/photos/singapore2010

While travelling to our Supercharge Your Science workshop in Cairns and Townsville last week (which, by the way, went off really well and the punters gave us the thumbs up – stay tuned for more Supercharge activities at a university near you…), I stumbled across an article in the Sydney Morning Herald about the state of Australia.

That Commonwealth purveyor of numbers, the Australian Bureau of Statistics (ABS), put together a nice little summary of various measures of wealth, health, politics and environment and their trends over the last decade. The resulting Measures of Australia’s Progress is an interesting read indeed. I felt the simple newspaper article didn’t do the environmental components justice, so I summarise the salient points below and give you my tuppence as well. Read the rest of this entry »








Follow

Get every new post delivered to your Inbox.

Join 6,719 other followers

%d bloggers like this: