Life-Long Mosquito Marking: Are Stable Isotopes the Key?

Post provided by ROY FAIMAN

Importance of Marking (Wild) Mosquitoes

Dr. Dao (crouching on right) and team with Dr. Tovi Lehmann (with sandals), Dr. Yaro (with white cap), and Moussa Diallo (front).

The fact that mosquitoes are insects of massive importance is of little dispute. With malaria still killing almost half a million people annually and after recent outbreaks of Zika, dengue and West-Nile viruses the threat of mosquito-borne diseases is becoming common knowledge. The meme of ‘Mosquitoes are the No.1 killer of all time,’ is also growing more popular (I even heard it from my 8-year-old kid one day after he returned from school!). Yet, with all we think we know about the little bug(ger)s, it’s probably only the tip of the iceberg.

Much work was done over the past century to try to answer basic questions about mosquitoes like:

  • How big are their populations?
  • How long do they live?
  • Where do they go when we don’t see or feel them?

Different methods have been developed to provide insights and notions on the mosquitoes’ movements, survival, and populations estimates; but the limitations and conditions of these methods mean that our knowledge is still incomplete.

One of the gold-standard tools for answering questions like those above is Mark-Release-Recapture (MRR). It was developed almost a century ago and has been modified and remodified through the years, as different marking technologies became available. Continue reading

A More Reliable Method for Estimating Abundance: Close-Kin Mark-Recapture

Post provided by DANIEL RUZZANTE

Knowing how many individuals there are in a population is a fundamental objective in ecology and conservation biology. But estimating abundance is often extremely difficult. It’s particularly difficult in the management of exploited marine, anadromous and freshwater populations. In marine fisheries, abundance estimation traditionally relies on demographic models, costly and time consuming mark recapture (MR) approaches if they are feasible at all, and the relationship between fishery catches and effort (catch per unit effort or CPUE). CPUEs can be subject to bias and uncertainty. This is why they tend to be considered relatively unreliable and contentious.

Close-Kin Mark-Recapture: Reducing Bias and Uncertainty

There is an alternative method though. It’s known as “Close-Kin Mark-Recapture” (CKMR), and is grounded in genomics and was first proposed by Skaug in 2001. The method is based on the principle that an individual’s genotype can be considered a “recapture” of the genotypes of each of its parents. Assuming the sampling of offspring and parents is independent of each other, the number of Parent-Offspring pairs (POP) genetically identified in a large collection of both groups can be used to estimate abundance. Continue reading

Advances in Modelling Demographic Processes: A New Cross-Journal Special Feature

Analysis of datasets collected on marked individuals has spurred the development of statistical methodology to account for imperfect detection. This has relevance beyond the dynamics of marked populations. A couple of great examples of this are determining site occupancy or disease infection state.

EURING Meetings

The regular series of EURING-sponsored meetings (which began in 1986) have been key to this development. They’ve brought together biological practitioners, applied modellers and theoretical statisticians to encourage an exchange of ideas, data and methods.

This new cross-journal Special Feature between Methods in Ecology and Evolution and Ecology and Evolution, edited by Rob Robinson and Beth Gardner, brings together a collection of papers from the most recent EURING meeting. That meeting was held in Barcelona, Spain, 2017, and was hosted by the Museu de Ciènces Naturals de Barcelona. Although birds have provided a convenient focus, the methods are applicable to a wide range of taxa, from plants to large mammals. Continue reading

Mark-Recapture and Metapopulation Structure: Using Study Design to Minimize Heterogeneity

Post provided by Delphine Chabanne

Pod of bottlenose dolphins observed in Cockburn Sound, Perth, Western Australia.

Pod of bottlenose dolphins observed in Cockburn Sound, Perth, Western Australia.

Wildlife isn’t usually uniformly or randomly distributed across land- or sea-scapes. It’s typically distributed across a series of subpopulations (or communities). The subpopulations combined constitute a metapopulation. Identifying the size, demography and connectivity between the subpopulations gives us information that is vital to local-species conservation efforts.

What is a Metapopulation?

Richard Levins developed the concept of a metapopulation to describe “a population of populations”. More specifically, the term metapopulation has been used to describe a spatially structured population that persists over time as a set of local populations (or subpopulations; or communities).  Emigration and immigration between subpopulations can happen permanently (through additions or subtractions) or temporarily (through the short-term presence or absence of individuals).

How individuals could distribute themselves within an area.

How individuals could distribute themselves within an area.

Continue reading

Measuring Survival Selection in Natural Populations: How important is recapture probability?

Post Provided by John Waller

The “Lande-Arnold” Approach

Damselflies marked in the field, which will hopefully be recaptured later. This small insect at our field site had only about 10% recapture probability.

Damselflies marked in the field, which will hopefully be recaptured later. This small insect at our field site had only about 10% recapture probability.

The quantification of survival selection in the field has a long history in evolutionary biology. A considerable milestone in this field was the highly influential publication by Russel Lande and Steve Arnold in the early 1980s.

The practical implementation of Lande and Arnold’s method involved simply fitting a linear model with standardized response (survival) and explanatory (trait) variables values with quadratic terms (multiplied by two). This straightforward method allowed evolutionary biologists to measure selection coefficients using commonly available statistical software and these estimates could be used directly within a quantitative genetic framework.  Continue reading

Statistics in Ecology and Environmental Monitoring: A Look Back at the SEEM 2015 Conference

Post provided by Dr Matt Schofield

Matt is an Associate Editor for Methods in Ecology and Evolution. He was the principle organiser of this year’s SEEM conference. His research interests include Bayesian inference and hierarchical modelling, computational methodology, ecological statistics and much more. Matt is based at the University of Otago.

A photo taken during a lunch break at the conference

A photo taken during a lunch break at the conference

The Statistics in Ecology and Environmental Monitoring (SEEM) conference was held in Queenstown, New Zealand on June 22-26, 2015. Queenstown is a resort town in the Southern Alps of New Zealand that looks out on Lake Wakatipu, surrounded by snow-capped mountains. The venue gave a chance to explore some of the natural beauty of New Zealand, with excursions to local ski fields, wineries and various hiking trails.

SEEM conferences have been organized by members of the Statistics group at the University of Otago since 1993. The first SEEM conference was held in Dunedin, New Zealand and conferences were then held regularly (every 3 years) until 2002. The last SEEM conference, in 2007, also served as the EURING (European Union for Bird Ringing) technical meeting. With nearly ten years passing since 2007, we had a smaller conference of around 50 attendees this year. There was an engaging atmosphere during the meeting and productive discussion followed each of the 40 talks. The SEEM 2015 meeting maintained the tradition of previous SEEM conferences with delegates from across a broad spectrum of statistical ecology coming together to discuss research. Continue reading