Sex on the beach

2 10 2018
Female green turtles (Chelonia mydas) spawning (top) and diving (bottom) on Raine Island (Great Barrier Reef, Queensland, Australia) — photos courtesy of Ian Bell. This species is ‘Endangered’ globally since 1982, mainly from egg harvesting (poaching conflict in Mexico for olive ridley Lepidochelys olivacea featured by National Geographic’s video here), despite the success of conservation projects (39). Green turtles inhabit tropical and subtropical seas in all oceans. Adults can grow > 150 kg and live for up to ~ 75 years. Right after birth, juveniles venture into the open sea to recruit ultimately in coastal areas until sexual maturity. They then make their first reproductive migration, often over 1000s of km (see footage of a real dive of a camera-equipped green turtle), to reach their native sandy beaches where pregnant females will lay their eggs. Each female can deposit more than one hundred eggs in her nest, and in several clutches in the same season because they can store the sperm from multiple mating events.

When sex is determined by the thermal environment, males or females might predominate under sustained climatic conditions. A study about marine turtles from the Great Barrier Reef illustrates how feminisation of a population can be partitioned geographically when different reproductive colonies are exposed to contrasting temperatures.

Fortunately, most people in Western societies already perceive that we live in a complex blend of sexual identities, far beyond the kind of genitals we are born with. Those identities start to establish themselves in the embryo before the sixth week of pregnancy. In the commonest scenario, for a human foetus XY with one maternal chromosome (X) and one paternal (Y) chromosome, the activation of the Sry gen (unique to Y) will trigger the differentiation of testicles and, via hormonal pathways, the full set of male characteristics (1).

Absence of that gene in an XX embryo will normally lead to a woman. However, in just one of many exceptions to the rule, Sry-expression failure in XY individuals can result in sterile men or ambiguous genitals — along a full gradient of intermediate sexes and, potentially, gender identities. A 2015 Nature ‘News’ feature echoes two extraordinary cases: (i) a father of four children found to bear a womb during an hernia operation, and (ii) a pregnant mother found to host both XX and XY cells during a genetic test – with her clinical geneticist stating “… that’s the kind of science-fiction material for someone who just came in for an amniocentesis” (2). These real-life stories simply reflect that sex determination is a complex phenomenon.

Three ways of doing it

In nature, there are three main strategies of sex determination (3) — see scheme here: Read the rest of this entry »





Legacy of human migration on the diversity of languages in the Americas

12 09 2018

quechua-foto-ale-glogsterThis might seem a little left-of-centre for CB.com subject matter, but hang in there, this does have some pretty important conservation implications.

In our quest to be as transdisciplinary as possible, I’ve team up with a few people outside my discipline to put together a PhD modelling project that could really help us understand how human colonisation shaped not only ancient ecosystems, but also our own ancient cultures.

Thanks largely to the efforts of Dr Frédérik Saltré here in the Global Ecology Laboratory, at Flinders University, and in collaboration with Dr Bastien Llamas (Australian Centre for Ancient DNA), Joshua Birchall (Museu Paraense Emílio Goeldi, Brazil), and Lars Fehren-Schmitz (University of California at Santa Cruz, USA), I think the student could break down a few disciplinary boundaries here and provide real insights into the causes and consequences of human expansion into novel environments.

Interested? See below for more details?

Languages are ‘documents of history’ and historical linguists have developed comparative methods to infer patterns of human prehistory and cultural evolution. The Americas present a more substantive diversity of indigenous language stock than any other continent; however, whether such a diversity arose from initial human migration pathways across the continent is still unknown, because the primary proxy used (i.e., archaeological evidence) to study modern human migration is both too incomplete and biased to inform any regional inference of colonisation trajectories. Read the rest of this entry »





Minister, why is the dingo no longer ‘fauna’?

7 09 2018

dead dingoSo, a few of us have just submitted a letter contesting the Western Australia Government’s recent decision to delist dingoes as ‘fauna’ (I know — what the hell else could they be?). The letter was organised brilliantly by Dr Kylie Cairns (University of New South Wales), and she and the rest of the signatories have agreed to reproduce the letter in full here on ConservationBytes.com. If you feel so compelled, please voice your distaste of this decision officially by contacting the Minister (details below).

CJA Bradshaw

Honourable Stephen Dawson MLC
Minister for Environment; Disability Services
Address: 12th Floor, Dumas House
2 Havelock Street, WEST PERTH WA 6005
(minister.dawson@dpc.wa.gov.au)

cc: Department of Biodiversity, Conservation and Attractions (biodiversity@dbca.wa.gov.au)
cc: Brendan Dooley (brendan.dooley@dpc.wa.gov.au)

Dear Minister,

The undersigned welcome the opportunity to comment on and recommend alteration of the proposed section (9)(2) order of the Biodiversity Conservation Act 2016 (BC Act) that changes the listing of the dingo from “fauna” to “non-fauna” in Western Australia. Removing the “fauna” status from dingoes has serious consequences for the management and conservation of this species and other native biota it benefits. Currently, dingoes are classed as A7, or fauna that requires a management policy. The proposed section (9)(2) order will move dingoes (as “non-fauna”) to the A5 class, meaning that dingoes must be (lethally) controlled and there will be no obligation for the Department of Biodiversity, Conservation and Attractions to have an appropriate management policy (or approval).

Currently, under the Wildlife Conservation Act 1950 (WC Act) the dingo is considered “unprotected” fauna allowing management under a Department of Biodiversity, Conservation and Attractions management policy. A section (9)(2) order demoting dingoes to “non-fauna” will remove the need for Department of Biodiversity, Conservation and Attractions management policy and instead mandate the lethal control of dingoes throughout Western Australia.

As prominent researchers in top predator ecology, biology, cultural value and genetics, we emphasise the importance of dingoes within Australian, and particularly Western Australia’s ecosystems. Dingoes are indisputably native based on the legislative definition of “any animal present in Australia prior to 1400 AD” from the BC Act. Dingoes have been present in Australia for at least 5000 years. On the Australian mainland they are now the sole non-human land-based top predator. Their importance to the ecological health and resilience of Australian ecosystems cannot be overstated. Read the rest of this entry »





Some scary stats about agriculture and biodiversity

20 07 2018

84438Last week we had the pleasure of welcoming the eminent sustainability scientist, Professor Andrew Balmford of the University of Cambridge, to our humble Ecology and Evolution Seminar Series here at Flinders University. While we couldn’t record the seminar he gave because of some of the unpublished and non-proprietary nature of some of his slides, I thought it would be interesting, useful, and thought-provoking to summarise some of the information he gave.

Andrew started off by telling us some of the environmental implications of farming worldwide. Today, existing agriculture covers more than half of ‘useable’ land (i.e., excluding unproductive deserts, etc.), and it has doubled nitrogen fixation rates from a pre-industrial baseline. Globally, agriculture is responsible for between 19 and 35% of all greenhouse gas emissions, and it has caused approximately 40% increase in observed sea-level rise (1961-2003). Not surprisingly, agriculture already occupies the regions of highest biodiversity globally, and is subsequently the greatest source of threat to species.

Read the rest of this entry »





Greater death rates for invasive rabbits from interacting diseases

30 05 2018

When it comes to death rates for invasive European rabbits (Oryctolagus cuniculus) in Australia, it appears that 1 + 1 = 2.1.

Pt tagged rab with RHD+myxo 1 10-08

Tagged European rabbit kitten infected with myxoma virus, but that died from rabbit haemorrhagic virus disease (RHDV). Photo by David Peacock, Biosecurity South Australia.

“Canberra, we have a problem” — Sure, it’s an old problem and much less of one than it used to be back in the 1950s, but invasive rabbits are nonetheless an ecological, conservation, and financial catastrophe across Australia.

relative rabbit abundance South Australia

Semi-schematic diagram, redrawn using data from Saunders and others and extended to include the recent spread of RHDV2, showing changes in rabbit abundance in relation to the introduction of biological control agents into north-eastern South Australia. Dotted lines indicate uncertainty due to lack of continuous annual data. The broken line indicates a level of about 0.5 rabbits ha-1, below which rabbits must be held to ensure recovery of native pastures and shrubs (from B. Cooke 2018 Vet Rec doi:10.1136/vr.k2105)

Rabbits used to reach plague numbers in much of agricultural and outback Australia, but the introduction and clever manipulation of two rather effective rabbit-specific viruses and insect vectors — first, myxoma virus in 1950, European rabbit fleas in the 1960s to help spread the virus, then Spanish rabbit fleas in the 1990s to increase spread into arid areas, and then rabbit haemorrhagic disease virus (RHDV) in 1995 — have been effective in dropping rabbit abundances by an estimated 75-80% in South Australia alone since the 1950s.

Read the rest of this entry »





What Works in Conservation 2018

23 05 2018
P1230308

Do you have a copy of this book? If not, why not?

 

This book is free to download. This book contains the evidence for the effectiveness of over 1200 things you might do for conservation. If you don’t have a copy, go and download yourself a free one here, right now, before you even finish reading this article. Seriously. Go. You’ll laugh, you’ll cry, it’ll change your life.

Why you’ll laugh

OK, I may have exaggerated the laughing part. ‘What Works in Conservation 2018’ is a serious and weighty tome, 660 pages of the evidence for 1277 conservation interventions (anything you might do to conserve a species or habitat), assessed by experts and graded into colour-coded categories of effectiveness. This is pretty nerdy stuff, and probably not something you’ll lay down with on the beach or dip into as you enjoy a large glass of scotch (although I don’t know your life, maybe it is).

But that’s not really what it’s meant for. This is intended as a reference book for conservation managers and policymakers, a way to scan through your possible solutions and get a feel for those that are most likely to be effective. Once you have a few ideas in mind, you can follow the links to see the full evidence base for each study at conservationevidence.com, where over 5000 studies have been summarised into digestible paragraphs.

The book takes the form of discrete chapters on taxa, habitats or topics (such as ‘control of freshwater invasives’). Each chapter is split into IUCN threat categories such as ‘Agriculture’ or ‘Energy production and mining’. For each threat there are a series of interventions that could be used to tackle it, and for each of these interventions the evidence has been collated. Experts have then graded the body of the evidence over three rounds of Delphi scoring, looking at the effectiveness, certainty in the evidence (i.e., the quality and quantity of evidence available), and any harms to the target taxa. These scores combine to place each intervention in a category from ‘Beneficial’ to ‘Likely to be ineffective or harmful’. Read the rest of this entry »





My interview with Conservation Careers

10 04 2018

IMage-2

The online job-search engine and careers magazine for conservation professionals — Conservation Careers — recently published an interview with me written by Mark Thomas. Mark said that he didn’t mind if I republished the article here.

As we walk through life we sometimes don’t know where our current path will take us. Will it be meaningful, and what steps could we take? Seeking out and talking to people who have walked far ahead of us in a line of work that we are interested in could help shape the next steps we take, and help us not make the same mistakes that could have cost us precious time.

A phrase that I love is “standing on the shoulders of giants” and this conversation has really inspired me — I hope it will do for you as well.

Corey Bradshaw is the Matthew Flinders Fellow in Global Ecology at Flinders University, and author to over 260 hundred peer-reviewed articles. His research is mainly in the area of global-change ecology, and his blog ConservationBytes critiques the science of conservation and has over 11,000 followers. He has written books, and his most recent one ‘The Effective Scientist’ will be published in March (more on this later).

What got you interested in ecology and conservation?

As a child I grew up in British Columbia, Canada, my father was a fur trapper, and we hunted everything we ate (we ate a lot of black bear). My father had lots of dead things around the house and he prepared the skins for the fur market. It was a very consumptive and decidedly non-conservation upbringing.

Ironically, I learnt early in life that some of the biggest impediments to deforestation through logging was the trapping industry, because when you cut down trees nothing that is furry likes to live there. In their own consumptive ways, the hunters were vocal and acted to protect more species possibly than what some dedicated NGOs were able to.

So, at the time, I never fully appreciated it, but not having much exposure to all things urban and the great wide world, and by spending a lot of time out in the bush, I ended up appreciating the conservation of wild things even within that consumptive mind-set. Read the rest of this entry »