Animal Demography Research Articles

Using spaceborne LiDAR to reveal drivers of animal demography.

Remote sensing can provide continuous spatiotemporal information about vegetation to inform wildlife habitat estimates, but these methods are often limited in availability or lack adequate resolution to capture the three-dimensional vegetative details critical for understanding habitat. The Global Ecosystem Dynamics Investigation (GEDI) is a spaceborne light detection and ranging system (LiDAR) that has revolutionized the availability of high-quality three-dimensional vegetation measurements of the Earth's temperate and tropical forests. To date, wildlife-related applications of GEDI data or GEDI-fusion products have been limited to estimate species habitat use, distribution, and diversity. Here, our goal was to expand the use of GEDI-based applications to wildlife demography by evaluating if GEDI data fusions could aid in characterizing demographic parameters of wildlife. We leveraged a recently published dataset of GEDI-fusion forest structures and capture-mark-recapture data to estimate the density and survival of two small mammal species, Humboldt's flying squirrel (Glaucomys oregonensis) and Townsend's chipmunk (Neotamias townsendii), from three studies in western Oregon spanning 2014-2021. We used capture histories in Huggins robust design models to estimate apparent annual survival and density as a derived parameter. We found strong support that both flying squirrel and chipmunk density were associated with GEDI-fusion forest structures of foliage height diversity and plant area volume density in the 5-10 m strata for flying squirrels and proportionately higher plant area volume density in the 0-20 m strata for chipmunks, as well as other spatiotemporal factors such as elevation. We found weak support that apparent annual survival was associated with GEDI-fusion forest structures for flying squirrels but not for chipmunks. We demonstrate further utility of these methods by creating spatially explicit density maps of both species that could aid management and conservation policies. Our work represents a novel application of GEDI data to evaluate wildlife demography and produce continuous spatially explicit density predictions for these species. We conclude that aspects of small mammal demography can be explained by forest structure as characterized via GEDI data fusions.

Importance sampling and Bayesian model comparison in ecology and evolution

Abstract Bayesian approaches to the modelling of ecological systems are increasingly popular, but there are competing methods for formal model comparisons. Here, we focus on the task of performing multimodel inference through estimating posterior model weights, which encompasses uncertainties in the choice of competing model structure into the inference outputs. Model‐based approaches such as reversible‐jump Markov chain Monte Carlo (RJ‐MCMC) are flexible and allow multimodel inference, but can be complex to implement and optimise, and so we translate a model‐based approach for ecological applications using Importance Sampling to estimate the marginal likelihood of the data given a particular model. This approach allows for model comparison through the estimation of Bayes' Factors or interpretable posterior model probabilities, yielding model weights that facilitate multimodel inference through Bayesian model averaging. We demonstrate Importance Sampling with two case study investigations in animal demography: censused analysis of banded mongoose (Mungos mungo) survival where missing data are uncommon, and capture–mark–recapture analysis of European badger (Meles meles) survival where data are commonly missing. We compare outcomes of the model comparison using the Importance Sampling approach to those obtained through single‐model inference approaches using Deviance information criteria and the Watanabe–Akaike information criteria. The results of the Importance Sampling method aligns with RJ‐MCMC model comparisons while often being more straightforward to fit and optimise, particularly if the competing models are non‐nested.

To tag ornot to tag: comparative performance of tagging and photo-identification in a long-term mark-recapture of Juvenile Green Turtles (Chelonia mydas)

Abstract Capture-mark-recapture (CMR) methods are widely used to estimate population parameters and to collect data on animal demography, migration, and life history. Sea turtle research programs generally use artificial tags, an invasive method. Photo-identification (PID) methods have become an important tool for animal identification. Herein, we assessed the effectiveness of a PID method for marking green turtles (Chelonia mydas) compared to traditional methods (artificial tags). As a part of a long-term CMR study, green turtles have been tagged and photographed since 2001. We analyzed 1917 captures with left and right side photographs of tagged turtles using Wild-ID software, these results were compared with tag-recapture data to assess error rates (false positives and negatives), and different effectiveness metrics. A combination of PID and tags (a match from either method was considered a recapture) was the most error-free and efficient criterion for identification of recaptures; however, it was the most time consuming and invasive criterion as well. We also assessed the effect of image quality indicators on the error rates of PID. We found that turtle cleanliness increases the similarity of images (indirectly related to false negatives), but we found no effect of sharpness, angle, light condition, or width and height in pixels of images on error rates. We could conclude that if image quality is improved, tags could be substituted by PID. However, we strongly recommend researchers to consider local situations (occurrence of by-catch or stranded dead turtles, for which tags are still necessary) before deciding to apply only PID.

A hierarchical model for jointly assessing ecological and anthropogenic impacts on animal demography.

The management of sustainable harvest of animal populations is of great ecological and conservation importance. Development of formal quantitative tools to estimate and mitigate the impacts of harvest on animal populations has positively impacted conservation efforts.The vast majority of existing harvest models, however, do not simultaneously estimate ecological and harvest impacts on demographic parameters and population trends. Given that the impacts of ecological drivers are often equal to or greater than the effects of harvest, and can covary with harvest, this disconnect has the potential to lead to flawed inference.In this study, we used Bayesian hierarchical models and a 43‐year capture–mark–recovery dataset from 404,241 female mallards Anas platyrhynchos released in the North American midcontinent to estimate mallard demographic parameters. Furthermore, we model the dynamics of waterfowl hunters and habitat, and the direct and indirect effects of anthropogenic and ecological processes on mallard demographic parameters.We demonstrate that density dependence, habitat conditions and harvest can simultaneously impact demographic parameters of female mallards, and discuss implications for existing and future harvest management models.Our results demonstrate the importance of controlling for multicollinearity among demographic drivers in harvest management models, and provide evidence for multiple mechanisms that lead to partial compensation of mallard harvest. We provide a novel model structure to assess these relationships that may allow for improved inference and prediction in future iterations of harvest management models across taxa.

Nestling sex ratio is unaffected by individual and population traits in the griffon vulture.

Variation in offspring sex ratios is a central topic in animal demography and population dynamics. Most studies have focused on bird species with marked sexual dimorphism and multiple-nestling broods, where the offspring sex ratio is often biased due to different individual or environmental variables. However, biases in offspring sex ratios have been far less investigated in monomorphic and single-egg laying species, and few studies have evaluated long-term and large-scale variations in the sex ratio of nestling vultures. Here, we explore individual and environmental factors potentially affecting the secondary sex ratio of the monomorphic griffon vulture Gyps fulvus. We used information collected at three breeding nuclei from central Spain over a 30-year period (1990-2020) to analyse the effects of nestling age, parental age, breeding phenology, conspecific density, population reproductive parameters, and spatial and temporal variability on nestling sex. Sex ratio did not differ from parity either at the population or the nuclei level. No significant between-year differences were detected, even under highly changing conditions of food availability associated with the mad-cow crisis. We found that tree nesting breeders tend to have more sons than daughters, but as this nesting behavior is rare and we consequently have a small sample size, this issue would require additional examination. Whereas further research is needed to assess the potential effect of breeder identity on nestling sex ratio, this study contributes to understanding the basic ecology and population dynamics of Griffon Vultures, a long-lived species with deferred maturity and low fecundity, whose minor deviations in the offspring sex ratio might imply major changes at the population level.

Local population collapse of Ross's and lesser snow geese driven by failing recruitment and diminished philopatry

Dynamics of free‐ranging animal populations can result from complex interplays of survival, recruitment and movement. Yet incomplete understanding of demography impedes conservation strategies intended to modify population dynamics of focal species. We estimated survival and per capita production of young, as well as emigration and immigration, from 1997 to 2017 in Ross's goose Anser rossii and lesser snow goose Anser caerulescens caerulescens, which are sympatric species of migratory birds that nest in the central Canadian Arctic at one of the largest breeding colonies in North America. We formed age‐structured integrated population models (IPMs) for each species that jointly analyzed live and dead encounter data as well as breeding adult population size and fecundity data to understand drivers of population dynamics. We compared the demography between species because both species increased during the 1990s and early 2000s yet thereafter snow geese declined, while Ross's geese continued to increase, then stabilized and similarly declined. Declines in Ross's and snow goose populations were caused by reduced per capita production of young, and juvenile survival, as well as increased adult and juvenile emigration. Stronger declines in juvenile survival in snow geese explain their earlier population decline compared to Ross's geese. Despite the divergence in population trends in Ross's and snow geese, we found strong synchrony in demographic rates which suggested substantial emigration from this colony and similar responses to environmental conditions. Direct estimation of demographic patterns in the IPM framework permitted hypothesis testing and inference about the role of immigration, even though immigrant sources were unsampled. We provide a novel m‐array implementation specific to a multi‐state Burnham model which greatly improved computational efficiency and convergence of posterior estimates. Our findings are an important reminder of the role that permanent movements can play in animal demography and metapopulation structure.

Modeling abundance, distribution, movement and space use with camera and telemetry data.

Studies of animal abundance and distribution are often conducted independently of research on movement, despite the important links between processes. Movement can cause rapid changes in spatial variation in density, and movement influences detection probability and therefore estimates of abundance from inferential methods such as spatial capture-recapture (SCR). Technological developments including camera traps and GPS telemetry have opened new opportunities for studying animal demography and movement, yet statistical models for these two data types have largely developed along parallel tracks. We present a hierarchical model in which both datasets are conditioned on a movement process for a clearly defined population. We fitted the model to data from 60 camera traps and 23,572 GPS telemetry locations collected on 17 male white-tailed deer in the Big Cypress National Preserve, Florida, USA during July 2015. Telemetry data were collected on a 3-4 h acquisition schedule, and we modeled the movement paths of all individuals in the region with a Ornstein-Uhlenbeck process that included individual-specific random effects. Two of the 17 deer with GPS collars were detected on cameras. An additional 20 male deer without collars were detected on cameras and individually identified based on their unique antler characteristics. Abundance was 126 (95% CI: 88-177) in the 228 km2 region, only slightly higher than estimated using a standard SCR model: 119 (84-168). The standard SCR model, however, was unable to describe individual heterogeneity in movement rates and space use as revealed by the joint model. Joint modeling allowed the telemetry data to inform the movement model and the SCR encounter model, while leveraging information in the camera data to inform abundance, distribution and movement. Unlike most existing methods for population-level inference on movement, the joint SCR-movement model can yield unbiased inferences even if non-uniform sampling is used to deploy transmitters. Potential extensions of the model include the addition of resource selection parameters, and relaxation of the closure assumption when interest lies in survival and recruitment. These developments would contribute to the emerging holistic framework for the study of animal ecology, one that uses modern technology and spatio-temporal statistics to learn about interactions between behavior and demography.

Mass-kill hunting and Late Quaternary ecology: New insights into the ‘desert kite’ phenomenon in Arabia

Over 6,000 ‘desert kites’—mass-kill stone hunting traps constructed at various times over the last 10,000 years—have been identified from northern Arabia to western central Asia. It has been proposed that kites had a significant impact on animal demography, leading to changes in ecology and human societies. While there has been considerable discussion regarding the function and chronology of kites, their spatial distribution is poorly understood. Here we report over 300 desert kites from several areas of the Arabian Peninsula, including ~ 500 km further south than previously suggested. Using satellite imagery, we studied their super-imposition revealing an extended chronology of kite-construction, including multiple phases of rebuilding in some cases and kites built relatively recently. This shows that desert kites were significantly more spatially and temporally widespread than previously believed, suggesting that they played a role in transforming Late Quaternary ecosystems and offering insights into the behaviour of human societies in challenging environments.

Connecting the data landscape of long-term ecological studies: The SPI-Birds data hub.

The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long‐term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad‐scale global issues (e.g. climate change).To solve data integration issues and enable a new scale of ecological and evolutionary research based on long‐term studies of birds, we have created the SPI‐Birds Network and Database (www.spibirds.org)—a large‐scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI‐Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting.SPI‐Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community‐derived data and meta‐data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata languages (e.g. ecological meta‐data language).The encouraging community involvement stems from SPI‐Bird's decentralized approach: research groups retain full control over data use and their way of data management, while SPI‐Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community‐specific hubs (such as ours, COMADRE for animal demography, etc.) will aid much‐needed large‐scale ecological data integration.

Breeding transients in capture\u2013recapture modeling and their consequences for local population dynamics

Standard procedures for capture–mark–recapture modelling (CMR) for the study of animal demography include running goodness-of-fit tests on a general starting model. A frequent reason for poor model fit is heterogeneity in local survival among individuals captured for the first time and those already captured or seen on previous occasions. This deviation is technically termed a transience effect. In specific cases, simple, uni-state CMR modeling showing transients may allow researchers to assess the role of these transients on population dynamics. Transient individuals nearly always have a lower local survival probability, which may appear for a number of reasons. In most cases, transients arise due to permanent dispersal, higher mortality, or a combination of both. In the case of higher mortality, transients may be symptomatic of a cost of first reproduction. A few studies working at large spatial scales actually show that transients more often correspond to survival costs of first reproduction rather than to permanent dispersal, bolstering the interpretation of transience as a measure of costs of reproduction, since initial detections are often associated with first breeding attempts. Regardless of their cause, the loss of transients from a local population should lower population growth rate. We review almost 1000 papers using CMR modeling and find that almost 40% of studies fitting the searching criteria (N = 115) detected transients. Nevertheless, few researchers have considered the ecological or evolutionary meaning of the transient phenomenon. Only three studies from the reviewed papers considered transients to be a cost of first reproduction. We also analyze a long-term individual monitoring dataset (1988–2012) on a long-lived bird to quantify transients, and we use a life table response experiment (LTRE) to measure the consequences of transients at a population level. As expected, population growth rate decreased when the environment became harsher while the proportion of transients increased. LTRE analysis showed that population growth can be substantially affected by changes in traits that are variable under environmental stochasticity and deterministic perturbations, such as recruitment, fecundity of experienced individuals, and transient probabilities. This occurred even though sensitivities and elasticities of these parameters were much lower than those for adult survival. The proportion of transients also increased with the strength of density-dependence. These results have implications for ecological and evolutionary studies and may stimulate other researchers to explore the ecological processes behind the occurrence of transients in capture–recapture studies. In population models, the inclusion of a specific state for transients may help to make more reliable predictions for endangered and harvested species.

Direct and indirect effects of nesting density on survival and breeding propensity of an endangered shorebird

AbstractDensity‐dependent regulation is a fundamental part of ecological theory and a significant driver of animal demography often through complex feedback loops. We investigated the relationship between flood‐ and demographically induced fluctuations in density and the breeding propensity and survival of a pioneer species, the piping plover (plover, Charadrius melodus). We captured and marked adult and hatchling plovers on the Gavins Point Reach of the Missouri River in South Dakota and Nebraska, USA, from 2005 to 2014. In 2010 and 2011, historically high water levels and flooding inundated much of the plover's sandbar nesting habitat on the Missouri River. We developed a Bayesian formulation of a multievent model, or a multistate survival model with state uncertainty to estimate breeding propensity simultaneously with survival. Although plovers are conspicuous, their breeding status can be difficult to establish with certainty, which necessitated the use of uncertain states. With this model, we investigated the effect of sex, habitat availability, river flow, and density (birds/ha nesting habitat) on survival of hatch year and breeding and non‐breeding adult plovers. In addition, we estimated the transition rates for these age classes between breeding and non‐breeding states. Non‐breeding adults ( = 0.58 ± 0.06) had lower survival rates than breeding adults ( = 0.80 ± 0.04), and both breeding survival and breeding propensity decreased with increasing nesting density. Not only did survival and breeding propensity decrease directly at higher nest densities, but survival also was indirectly impacted by increasing the proportion of non‐breeding birds with relatively low survival. Thus, plovers were regulated through a complex set of feedback loops, acting as densities increased. Our findings underscore the intricacy of density‐dependent regulation and suggest that detailed demographic studies are needed to fully understand these effects.

Integrando mecanismos evolutivos y dinámica de poblaciones de plantas: una perspectiva desde la demografía animal

Paniw, M. 2019. Perspectives from animal demography on incorporating evolutionary mechanism into plant population dynamics. Ecosistemas 28(1):60-68. Doi.: 10.7818/ECOS.1640 With a growing number of long-term, individual-based data on natural populations, it has become increasingly evident that environmental change affects populations through complex, simultaneously occurring demographic and evolutionary processes. Analyses of population-level responses to environmental change must therefore integrate demography and evolution into one coherent framework. Integral projection models (IPMs), which can relate genetic and phenotypic traits to demographic and population-level processes, offer a powerful approach for such integration. However, a rather artificial division exists in how plant and animal population ecologists use IPMs. Here, I argue for the integration of the two sub-disciplines, particularly focusing on how plant ecologists can diversify their toolset to investigate selection pressures and eco-evolutionary dynamics in plant population models. I provide an overview of approaches that have applied IPMs for eco-evolutionary studies and discuss a potential future research agenda for plant population ecologists. Given an impending extinction crisis, a holistic look at the interacting processes mediating population persistence under environmental change is urgently needed.

Companion animal demography and population management in Pinhais, Brazil

We used a two-stage cluster sampling design to estimate the population sizes of owned dogs and cats in Pinhais, Brazil. For dogs, we simulated the population dynamics using a compartmental model of coupled differential equations, incorporating uncertainties in a global sensitivity analysis and identifying the most influential parameters through local sensitivity analysis. The calibration with the known human population improved precision in population size for dogs but not for cats. Population pyramids had a wide base, and the apparent population turnover was lower than the net population gain. Most immigrants came from the state capital. Projected dog and human growth rates between 2017 and 2027 were positive and similar, while the projected proportion of sterilized dogs decreased over the same period. The main reason provided for not sterilizing animals was the cost of the procedure, even though there were free alternatives. The demographic characterization made in the present study will serve for future comparisons and as a reference in epidemiological contexts. The simulations indicated what to expect in specific scenarios and stressed the need to increase current sterilization rates.

Correction to 'Can't live with them, can't live without them? Balancing mating and competition in two-sex populations'.

You have accessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Compagnoni A., Steigman K. and Miller T. E. X. 2017Correction to ‘Can't live with them, can't live without them? Balancing mating and competition in two-sex populations’Proc. R. Soc. B.2842017258320172583http://doi.org/10.1098/rspb.2017.2583SectionYou have accessCorrectionCorrection to ‘Can't live with them, can't live without them? Balancing mating and competition in two-sex populations’ A. Compagnoni A. Compagnoni http://orcid.org/0000-0001-8302-7492 Google Scholar Find this author on PubMed Search for more papers by this author , K. Steigman K. Steigman Google Scholar Find this author on PubMed Search for more papers by this author and T. E. X. Miller T. E. X. Miller Google Scholar Find this author on PubMed Search for more papers by this author A. Compagnoni A. Compagnoni http://orcid.org/0000-0001-8302-7492 Google Scholar Find this author on PubMed Search for more papers by this author , K. Steigman K. Steigman Google Scholar Find this author on PubMed Search for more papers by this author and T. E. X. Miller T. E. X. Miller Google Scholar Find this author on PubMed Search for more papers by this author Published:13 December 2017https://doi.org/10.1098/rspb.2017.2583This article corrects the followingResearch ArticleCan't live with them, can't live without them? Balancing mating and competition in two-sex populationshttps://doi.org/10.1098/rspb.2017.1999 Aldo Compagnoni, Kenneth Steigman and Tom E. X. Miller volume 284issue 1865Proceedings of the Royal Society B: Biological Sciences25 October 2017Proc. R. Soc. B284, 20171999 (published online 25 October 2017) (doi:10.1098/rspb.2017.1999)Compagnoni et al. [1] erroneously refer to the COMPADRE plant demographic database [2]. The correct citation should instead refer to the COMADRE animal demographic database [3].Footnotes© 2017 The Author(s)Published by the Royal Society. All rights reserved.References1Compagnoni A, Steigman K, Miller TEX. 2017Can't live with them, can't live without them? Balancing mating and competition in two-sex populations. Proc. R. Soc. B 284, 20171999. (doi:10.1098/rspb.2017.1999) Link, ISI, Google Scholar2Salguero-Gómez Ret al.2015The compadre plant matrix database: an open online repository for plant demography. J. Ecol. 103, 202–218. (doi:10.1111/1365-2745.12334) Crossref, ISI, Google Scholar3Salguero-Gómez Ret al.2016COMADRE: a global data base of animal demography. J. Anim. Ecol. 85, 371–384. (doi:10.1111/1365-2656.12482) Crossref, PubMed, ISI, Google Scholar Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesCan't live with them, can't live without them? Balancing mating and competition in two-sex populations25 October 2017Proceedings of the Royal Society B: Biological Sciences This Issue20 December 2017Volume 284Issue 1869 Article InformationDOI:https://doi.org/10.1098/rspb.2017.2583PubMed:29237864Published by:Royal SocietyOnline ISSN:1471-2954History: Published online13/12/2017Published in print20/12/2017 License:© 2017 The Author(s)Published by the Royal Society. All rights reserved. Citations and impact Subjectsecology Large datasets are available through Proceedings B's partnership with Dryad

European policies on livestock carcasses management did not modify the foraging behavior of a threatened vulture

Policy decisions have the potential to affect biodiversity conservation and modify, among other factors, animal demography, behavior and ecological processes. This became manifest in Europe in the past decade in light of the appearance of bovine spongiform encephalopathy (BSE). However, the obvious effects of policy decisions on foraging behavior are lacking. Here, we use data from a long-term study (1992–2015) of the ecology of the bearded vulture Gypaetus barbatus in the Pyrenees to assess whether or not the implementation of health policies in the period 2006–2011 really did affect this vulture's foraging behavior and breeding success. To test this, we used the frequency of nest changeovers (between 1992 and 2015) as a surrogate for the time invested in searching for and obtaining food. Additionally, between 2006 and 2015 we monitored the movements of 20 bearded vultures with GPS satellite transmitters. Our findings show no differences between annual home range sizes and/or the time used to search for food either before, during or after the imposition of health regulations. No differences between periods (during or after health regulations) were found in the use of supplementary feeding sites (SFS). An analysis of food available indicates that this similarity of use in different periods could be explained by the high habitat quality in the Pyrenees and the good availability of trophic resources. Our results suggest that diet plasticity and habitat quality compensate for the sudden effects of food shortages and so question the true usefulness of SFS in buffering a quantitative food deficit. We discuss the implications of these results from both ecological and conservation perspectives.

COMADRE: a global data base of animal demography.

Summary The open‐data scientific philosophy is being widely adopted and proving to promote considerable progress in ecology and evolution. Open‐data global data bases now exist on animal migration, species distribution, conservation status, etc. However, a gap exists for data on population dynamics spanning the rich diversity of the animal kingdom world‐wide. This information is fundamental to our understanding of the conditions that have shaped variation in animal life histories and their relationships with the environment, as well as the determinants of invasion and extinction.Matrix population models (MPMs) are among the most widely used demographic tools by animal ecologists. MPMs project population dynamics based on the reproduction, survival and development of individuals in a population over their life cycle. The outputs from MPMs have direct biological interpretations, facilitating comparisons among animal species as different as Caenorhabditis elegans, Loxodonta africana and Homo sapiens.Thousands of animal demographic records exist in the form of MPMs, but they are dispersed throughout the literature, rendering comparative analyses difficult. Here, we introduce the COMADRE Animal Matrix Database, an open‐data online repository, which in its version 1.0.0 contains data on 345 species world‐wide, from 402 studies with a total of 1625 population projection matrices. COMADRE also contains ancillary information (e.g. ecoregion, taxonomy, biogeography, etc.) that facilitates interpretation of the numerous demographic metrics that can be derived from its MPMs. We provide R code to some of these examples. Synthesis: We introduce the COMADRE Animal Matrix Database, a resource for animal demography. Its open‐data nature, together with its ancillary information, will facilitate comparative analysis, as will the growing availability of databases focusing on other aspects of the rich animal diversity, and tools to query and combine them. Through future frequent updates of COMADRE, and its integration with other online resources, we encourage animal ecologists to tackle global ecological and evolutionary questions with unprecedented sample size.

Butterfly conservation in Southern Africa

The origins and development of butterfly conservation in southern Africa are explored and the role of the Lepidopterists’ Society of Africa (LSA) in the promotion of butterfly conservation and research is described. LSA members have produced several Red Lists for South African butterflies. The Southern African Butterfly Conservation Assessment project, a joint venture between LSA, the Animal Demography Unit (ADU—University of Cape Town) and the South African National Biodiversity Institute was launched in 2007. This has resulted in a comprehensive and accurate distributional database and rigorous conservation assessments using the IUCN (2010) Red Listing categories and criteria for the 794 butterfly taxa assessed. LSA’s Custodians of Rare and Endangered Lepidoptera programme aims to conserve all the threatened species, prioritising the Critically Endangered category. Moving beyond species-based conservation, habitat and landscape conservation are now key conservation strategies which focus on vegetation types and butterfly biodiversity hotspots. LSA (in partnership with ADU) has also recently launched the LepiMAP project, an online photographic geo-referenced database which will develop a butterfly and moth atlas for the whole of Africa, as part of a continent-wide conservation effort. Another important project which the LSA recently launched is the Caterpillar Rearing Group, for documenting the life histories of all Lepidoptera in the Afrotropical region.

On the Selection of Representative Conservation Area-Networks

The problem of selection of representative conservation area-network is an important ecological issue related to preserving the biodiversity of a geographical region. The mathematical model is based on the assumption that environmental diversity is a good measure of biodiversity. In this setting, the geographical region is divided into smaller areas (assumed environmentally homogenous) which are mathematically considered as vertices of a graph. The environmental distance between two areas defines the length of the edge connecting the respective vertices. Selecting p areas which represent best the total of n areas (in the sense of environmental diversity) is mathematically equivalent to the so called $p$-median problem, that is selecting a set of $p$ vertices of the graph such that the sum of the distances from all vertices of the graph to the selected set is minimal. For any practically relevant values of n and p the solution cannot be computed in reasonable time, since this problem is a well-known NP hard problem. We discuss various heuristic methods to find an approximate solution in terms of the trade off between computational time and accuracy. In order to test the validity of the underlying assumption of the model we use species distribution datasets for birds, reptiles, and butterflies in South Africa. These datasets have been developed from extensive, formalised atlasing projects coordinated largely by the Animal Demography Unit of the University of Cape Town, and are the most comprehensive faunal species distribution datasets available for the country. Each vertex of the graph represents a quarter degree square (QDS), approximately 20km $\times$ 20km area commonly used in large biogeographic analysis. The total number of QDS for South Africa is 1816. The power of the method is demonstrated via numerical experiments with p ranging from 10 to 50.

Projection matrices revisited: a potential-growth indicator and the merit of indication

The mathematics of matrix models for age- and/or stage-structured population dynamics substantiates the use of the dominant eigenvalue λ 1 of the projection matrix L as a measure of the growth potential, or of adaptation, for a given species population in modern plant or animal demography. The calibration of L = T +F on the “identified-individuals-of-unknown-parents” kind of empirical data determines precisely the transition matrix T, but admits arbitrariness in the estimation of the fertility matrix F. We propose an adaptation principle that reduces calibration to the maximization of λ 1(L) under the fixed T and constraints on F ensuing from the data and expert knowledge. A theorem has been proved on the existence and uniqueness of the maximizing solution for projection matrices of a general pattern. A conjugated maximization problem for a “potential-growth indicator” under the same constraints has appeared to be a linear-programming problem with a ready solution, the solution testing whether the data and knowledge are compatible with the population growth observed.

Plants do not count… or do they? New perspectives on the universality of senescence.

1. Senescence, the physiological decline that results in decreasing survival and/or reproduction with age, remains one of the most perplexing topics in biology. Most theories explaining the evolution of senescence (i.e. antagonistic pleiotropy, accumulation of mutations, disposable soma) were developed decades ago. Even though these theories have implicitly focused on unitary animals, they have also been used as the foundation from which the universality of senescence across the tree of life is assumed.2. Surprisingly, little is known about the general patterns, causes and consequences of whole-individual senescence in the plant kingdom. There are important differences between plants and most animals, including modular architecture, the absence of early determination of cell lines between the soma and gametes, and cellular division that does not always shorten telomere length. These characteristics violate the basic assumptions of the classical theories of senescence and therefore call the generality of senescence theories into question.3. This Special Feature contributes to the field of whole-individual plant senescence with five research articles addressing topics ranging from physiology to demographic modelling and comparative analyses. These articles critically examine the basic assumptions of senescence theories such as age-specific gene action, the evolution of senescence regardless of the organism's architecture and environmental filtering, and the role of abiotic agents on mortality trajectories.4. Synthesis. Understanding the conditions under which senescence has evolved is of general importance across biology, ecology, evolution, conservation biology, medicine, gerontology, law and social sciences. The question ‘why is senescence universal or why is it not?’ naturally calls for an evolutionary perspective. Senescence is a puzzling phenomenon, and new insights will be gained by uniting methods, theories and observations from formal demography, animal demography and plant population ecology. Plants are more amenable than animals to experiments investigating senescence, and there is a wealth of published plant demographic data that enable interpretation of experimental results in the context of their full life cycles. It is time to make plants count in the field of senescence.