Inferring Extinction: When is a Species as Dead as a Dodo?

Post provided by ELIZABETH BOAKES

The indisputably extinct Dodo (Raphus cucullatus). ©Ballista

The indisputably extinct Dodo (Raphus cucullatus). ©Ballista

A species is either extant or extinct – it exists or it does not exist. Black and white, a binary choice. Surely it should not be difficult to assign species to one of these two categories? Well, in practice it can be extremely challenging and a plethora of methods have been developed to deal with the problem.  This of course leads to a second challenge – which of the plethora should you use?! (More on this later…)

There are a few well-studied cases where we can assert extinction confidently. For example, the chances of the Dodo (Raphus cucullatus) having existed undetected for upwards of 300 years on an island now densely populated by humans are infinitesimally small. However, many extinctions are far harder to diagnose. Species typically become extremely rare before becoming extinct. If taxa are particularly cryptic or are found across a huge geographic range it is quite plausible that the few remaining individuals may exist undetected for decades. An extreme illustration of this is the 1938 discovery of Latimeria chalumnae, a deep-sea member of the Coelacanths, the entire order of which was believed to have become extinct 80 million years earlier! Continue reading

International Women’s Day: What are the Biggest Problems Facing Gender Equality in STEM?

In recent years, there has been an increasing focus on encouraging women to join STEM fields, but there is still work that needs to be done. We asked our female Associate Editors what the biggest problems facing the push towards gender equality within STEM fields today are. Here are their answers:

janaJana McPherson: My impression is that entering is not the issue. Certainly in my fields of conservation and ecology, there seem to be lots of women undergraduates and graduates and still a very decent proportion of female postdocs. I think it is beyond that level that women start to become increasingly rare. At least in part this likely reflects the fact that it is around post-doc time that biological clocks start ticking, and that it is neither easy nor necessarily desirable to combine starting and raising a family with a prolific production of publications, a heavy teaching load and the need to magic up a bustling research lab out of the blue. To reduce that hurdle, I think universities and academics have to become more accepting and accommodating of part-time effort. And I mean institutionally as well as individually. I have conducted research on a part-time basis for years now, and have seen many colleagues and collaborators in academia positively flummoxed by the concept that NOTHING (work-wise) gets done between when I leave the office on a Thursday at 2pm and when I return to work Monday morning. And yes, my life outside the office involves minutes and the odd hour here and there where I’m not directly interacting with my kids or looking after the household during which I could theoretically get the odd bit of work done. But I have tried that approach and found it rather stressful, sleep-depriving and frustrating for family members competing for my attention with whatever ‘quick’ piece of work I was trying to finish.  So now I leave work at the office and whatever does not get done within office hours just has to wait until I’m next at work, no matter how urgent.

Tamara Munkemuller2Tamara Münkemüller: I guess that the main problems are related to family planning. On the one hand, in many countries it takes long to get a permanent position and it feels like taking a risk to have children before this. On the other hand, one seemingly frequent constellation are couples of two scientists where the man is a bit older. In this situation it often happens that the older person gets a permanent position first and the younger follows and tries to adapt. Then there is the more subtle problem of different communication styles of men and women and numerous selection processes that tend to prefer a communication style that is thought to be more typical for men.

Satu Ramula: I think that one of the current challenges is to keep women in the system. Many female scientists leave academia at some point, which makes the sex ratio skewed as there are not enough qualified women to compete for academic positions at upper levels. Continue reading

Revealing Biodiversity on Rocky Reefs using Natural Soundscapes

Post Provided by SYDNEY HARRIS

The Biodiversity Struggle

Typical rocky reef habitat in northeast New Zealand, characterized by encrusting red algae and Kelp forest. ©Sydney Harris

Typical rocky reef habitat in north east New Zealand, characterized by encrusting red algae and Kelp forest. ©Sydney Harris

By now we’re all familiar with the global biodiversity crisis: increasing numbers of species extinct or at risk of extinction; widespread habitat loss and a seemingly endless set of political, logistical and financial obstacles hampering swift action for conservation. The international Convention on Biological Diversity (CBD) has set twenty global diversity targets, many of which require participating nations to conduct accurate and efficient monitoring to assess their progress and inform policy decisions. Governing bodies and organizations worldwide have agreed that immediate, efficient action is essential to preserving our planet’s increasingly threatened ecosystems.

But how? Diversity measurement techniques are a tricky business. Accurately recording diversity can be time-consuming, labor-intensive, expensive, invasive and highly susceptible to human error. Often these methods involve the employment of trained specialists to individually identify hundreds or even thousands of species, a process that can take many months to complete.

Marine habitats are particularly difficult to access because of the physical limitations of humans underwater, and are often flawed due to the influence of our presence on marine organisms. However, the oceans contain many of the world’s most diverse systems, and, despite the limitations of current methods, the need to monitor marine diversity is a top priority for the global conservation movement. Continue reading

International Women’s Day: What Inspired You to Pursue a Career in Science?

Tomorrow (Tuesday 8 March) is International Women’s Day. To celebrate, we asked  our female Editors a few questions about gender equality (and other issues) in STEM and we’ll be posting their answers over the next four days.

We begin our International Women’s Day posts on a positive note, finding out a little more about our Editors. The first question that we asked them was: What made you want to pursue a career in science and were there any female scientists in particular who inspired you to pursue a career in STEM?

Jana VamosiJana Vamosi: I had no idea what I wanted to do until I was well into my twenties. I took a class in Evolutionary Biology at the end of my undergraduate degree. I loved learning the unifying theories and applying my nascent skills in biomathematics. I went on to start graduate studies with Dr Sally Otto at the University of British Columbia and her mentorship inspired me to consider a career in STEM.

Rachel_MccreaRachel McCrea: I always loved mathematics at school but never realised you could make a career out of it.  I didn’t think about my career path as such when choosing what to study at university but just chose a subject that I enjoyed.  My two (female) A-level maths teachers are to thank for me not pursuing medicine or veterinary science as they really supported me and taught me double-maths at A-level, even though only myself and one other student chose to take it.  I was inspired by Simon Singh’s book on Fermat’s Last Theorem and whilst at university I discovered that even though pure mathematics was not for me I really liked statistics so decided to study for an MSc.  Since then I have never turned back!  Continue reading

Demography and Big Data

Post provided by BRITTANY TELLER, KRISTIN HULVEY and ELISE GORNISH

Follow Brittany (@BRITTZINATOR) and Elise (@RESTORECAL) on Twitter

To understand how species survive in nature, demographers pair field-collected life history data on survival, growth and reproduction with statistical inference. Demographic approaches have significantly contributed to our understanding of population biology, invasive species dynamics, community ecology, evolutionary biology and much more.

As ecologists begin to ask questions about demography at broader spatial and temporal scales and collect data at higher resolutions, demographic analyses and new statistical methods are likely to shed even more light on important ecological mechanisms.

Population Processes

Midsummer Opuntia cactus in eastern Idaho, USA. © B. Teller.

Midsummer Opuntia cactus in eastern Idaho, USA. © B. Teller.

Traditionally, demographers collect life history data on species in the field under one or more environmental conditions. This approach has significantly improved our understanding of basic biological processes. For example, rosette size is a significant predictor of survival for plants like wild teasel (Werner 1975 – links to all articles are at the end of the post), and desert annual plants hedge their bets against poor years by optimizing germination strategies (Gremer & Venable 2014).

Demographers also include temporal and spatial variability in their models to help make realistic predictions of population dynamics. We now know that temporal variability in carrying capacity dramatically improves population growth rates for perennial grasses and provides a better fit to data than models with varying growth rates because of this (Fowler & Pease 2010). Moreover, spatial heterogeneity and environmental stochasticity have similar consequences for plant populations (Crone 2016). Continue reading

My Entropy ‘Pearl’: Using Turing’s Insight to Find an Optimal Estimator for Shannon Entropy

Post provided by Anne Chao (National Tsing Hua University, Taiwan)

Shannon Entropy

Not quite as precious as my entropy pearl

Not quite as precious as my entropy pearl ©Amboo Who

Ludwig Boltzmann (1844-1906) introduced the modern formula for entropy in statistical mechanics in 1870s. Since its generalization by Claude E. Shannon in his pioneering 1948 paper A Mathematical Theory of Communication, this entropy became known as ‘Shannon entropy’.

Shannon entropy and its exponential have been extensively used to characterize uncertainty, diversity and information-related quantities in ecology, genetics, information theory, computer science and many other fields. Its mathematical expression is given in the figure below.

In the 1950s Shannon entropy was adopted by ecologists as a diversity measure. It’s interpreted as a measure of the uncertainty in the species identity of an individual randomly selected from a community. A higher degree of uncertainty means greater diversity in the community.

Unlike species richness which gives equal weight to all species, or the Gini-Simpson index that gives more weight to individuals of abundant species, Shannon entropy and its exponential (“the effective number of common species” or diversity of order one) are the only standard frequency-sensitive complexity measures that weigh species in proportion to their population abundances. To put it simply: it treats all individuals equally. This is the most natural weighing for many applications. Continue reading