Breeding habitat selection behaviors in heterogeneous environments: implications for modeling reintroduction

Animal movement and habitat selection behavior are important considerations in ecology, and remain a major issue for successful animal reintroductions. However, simple rules are often used to model movement or focus only on intrinsic environmental cues, neglecting recent insights in behavioral ecology on habitat selection processes. In particular, social information has been proposed as a widespread source of information for habitat evaluation.
We investigated the role of explicit breeding habitat selection strategies on the establishment pattern of reintroduced populations and their persistence. We considered local movement at the scale of a single population. We constructed a spatially-implicit demographic model that considered five breeding habitat selection rules: 1) random, 2) intrinsic habitat quality, 3) avoidance of conspecifics, 4) presence of conspecifics and 5) reproductive success of conspecifics. The impact of breeding habitat selection was examined for different release methods under various levels of environmental heterogeneity levels, for both long and short-lived monogamous species.
When heterogeneity between intrinsic habitat patch qualities is high, the persistence of reintroduced populations strongly depends on habitat selection strategies. Strategies based on intrinsic quality and conspecific reproductive success lead to a lower reintroduction failure risk than random, conspecific presence or avoidance-based strategies. Conspecific presence or avoidance-based strategies may aggregate individuals in suboptimal habitats. The release of adults seems to be more efficient independent of habitat selection strategy.
We emphasize the crucial role of oriented habitat selection behavior and non ideal habitat selection in movement modeling, particularly for reintroduction.     

Effects of seasonality,isolation and patch quality for habitat selection processes by mute swans Cygnus olor in a fishpond landscape

Foragers in patchy environments do not only select sites for single patch characteristics, but also have to consider the local environment of such patches. We studied habitat selection by mute swans Cygnus olor in a wide and heterogeneous fishpond region (the Dombes, eastern France). In this study, we considered fishpond isolation, resource quality within fishponds and breeding status of mute swans during both summer and winter. Mute swans did not select aquatic habitat randomly within the landscape. During summer, the population spread preferentially on medium to large fishponds, in subregions with numerous or closely related waterbodies, without generating a clumped distribution of birds. In addition to a positive effect of local fishpond number (2 km radius), breeding birds also responded positively to fishpond size. Non‐breeders selected fishponds mainly according to their size. Intraspecific territoriality did not appear to limit the presence of non‐breeders (i.e. moulting flocks), since both breeders and non‐breeders could coexist on the larger fishponds. During winter, mute swans used medium to large reflooded fishponds after summer drainage. The surrounding aquatic environment of fishponds played a minor role in determining flocking, compared to actual patch quality. Flocking occurred on large fishponds that had reflooded after having dried the summer before, whatever the agricultural cultivation practiced in the summer following drainage. The results suggest that geographical aspects should be taken into account when considering the potential impact of this expanding species within such ecosystems, and also in more general management policies dealing with aquatic habitats for waterbird populations.     

Toward an ecological synthesis: a case for habitat selection

Habitat selection, and its associated density and frequency-dependent evolution, has a profound influence on such vital phenomena as population regulation, species interactions, the assembly of ecological communities, and the origin and maintenance of biodiversity. Different strategies of habitat selection, and their importance in ecology and evolution, can often be revealed simply by plots of density in adjacent habitats. For individual species, the strategies are closely intertwined with mechanisms of population regulation, and with the persistence of populations through time. For interacting species, strategies of habitat selection are not only responsible for species coexistence, but provide one of the most convenient mechanisms for measuring competition, and the various community structures caused by competitive interactions. Other kinds of interactions, such as those between predators and prey, demonstrate that an understanding of the coevolution of habitat-selection strategies among strongly interacting species is essential to properly interpret their spatial and temporal dynamics. At the evolutionary scale, the frequency dependence associated with habitat selection may often allow populations to diverge and diversify into separate species. Habitat selection thereby demonstrates how we can map microevolutionary strategies in behavior onto their population and community consequences, and from there, onto macroevolutionary patterns of speciation and adaptive radiation. We can anticipate that future studies of habitat selection will not only help us complete those maps, but that they will also continue to enrich the panoply of ideas that shape evolutionary ecology.     

Density-dependent habitat selection: evaluating isoleg theory with a Lotka-Volterra model

Contemporary models of density-dependent habitat selection generally focus on long-term evolutionary consequences of intraspecific or interspecific competition and/or patterns of resource use in patchy environments. A primary goal of such studies often is to elucidate evolutionary stable strategies based on steady-state dynamics of population growth. In contrast, we developed a simulation model to explore short-term movements of interspecific competitors among fine-grained habitats of differing attributes, as might result from field manipulations of habitat quality or population densities. In this model, habitat quality is expressed in terms of mean individual fitness, represented by average per capita growth rate calculated according to the Lotka-Volterra equations describing interspecific competition. This model provides a mechanism for quantifying the effects of habitat quality, patterns of resource use and competition on distributions of individuals. Results demonstrate the heuristic value of this model in corroborating predictions derived from the ideal free distribution and isodar theory, and in generating isolegs to test the predictions of isoleg theory. Results indicate that small changes in model parameters have substantial impacts on patterns of habitat use and co-occurrence between species. The model identifies a variety of conditions under which isolegs for a given type of community organization deviate from predictions of contemporary isoleg theory, potentially expanding the universe of possible interspecific behaviors underlying the development of evolutionary stable strategies.     

Long-term changes in population genetic features of a rapidly expanding marine invader: implication for invasion success

Large blooms of Rhopilema nomadica, a highly venomous rhizostamatid scyphozoan species introduced to the Mediterranean through the Suez Canal, have become ubiquitous in the summer and winter months along the Israeli coasts since the mid-1980s. This species has since spread across the eastern Mediterranean and was sighted as far west as Tunisia and Sardinia. For the past 12 years, we have studied changes in the mitochondrial COI haplotypes diversity of R. nomadica to investigate small scale fluctuactions of genetic diversity and to reveal possible genetic structuring of the fast spreading invader in the Eastern Mediterranean. The 1091 COI sequences analysed, revealed a highly diverse population displaying 89 haplotypes, 46 of which appeared as singletons, low frequency haplotypes. All the specimens analysed throughout the period belong to a single unstructured population. Though lacking data from the source population in the Red Sea, the high within-population diversity and the high diversity of COI haplotypes support the hypothesis of multiple introductions events, or an open corridor with a continuous influx of propagules. Tajima’s D and Fu’s Fst negative values and the increased numbers of COI singletons from early to late sampling periods, have verified that the Israeli population is characterized by a rapid expanding population. Further research is needed for the evaluation of COI diversity and patterns in R. nomadica populations across the eastern Mediterranean Sea and Red Sea, as well as any correlation of the high variability between COI locus and phenotypic diversity.

     

Estimation of local extinction rates when species detectability covaries with extinction probability: is it a problem?

Estimating the rate of change of the composition of communities is of direct interest to address many fundamental and applied questions in ecology. One methodological problem is that it is hard to detect all the species present in a community. Nichols et al. presented an estimator of the local extinction rate that takes into account species probability of detection, but little information is available on its performance. However, they predicted that if a covariance between species detection probability and local extinction rate exists in a community, the estimator of local extinction rate complement would be positively biased.
Here, we show, using simulations over a wide range of parameters that the estimator performs reasonably well. The bias induced by biological factors appears relatively weak. The most important factor enhancing the performance (bias and precision) of the local extinction rate complement estimator is sampling effort. Interestingly, a potentially important biological bias, such as the covariance effect, improves the estimation for small sampling efforts, without inducing a supplementary overestimation when these sampling efforts are high. In the field, all species are rarely detectable so we recommend the use of such estimators that take into account heterogeneity in species detection probability when estimating vital rates responsible for community changes.     

Tractable models for testing theories about natural strategies: foraging behaviour and habitat selection of free‐ranging sharks

Marine and terrestrial environments differ fundamentally in space‐time scales of both physical and ecological processes. These differences will have an impact on the animals inhabiting each domain, particularly with respect to their spatial ecology. The behavioural strategies that underpin observed distributions of marine species are therefore important to consider. Comparatively little is known, however, about how wild fishes actually respond to gradients in food supply and temperature, and to potential mates. This paper describes how behavioural theory is being used to elucidate the strategies and tactics of free‐ranging sharks in three specific areas of study, namely, foraging on zooplankton, behavioural energetics and sexual segregation. The studies discussed are novel because shark movements were tracked in the wild using electronic tags in relation to simultaneous measurements of prey densities and thermal resources. The results show that filter‐feeding (basking shark, Cetorhinus maximus ) and predatory (dogfish, Scyliorhinus canicula ) sharks have relatively complex behaviour patterns integrally linked to maximizing surplus power, often through making short and longer term 'trade‐off' decisions between optimal foraging and thermal habitats. Interestingly, female S. canicula exhibit alternative behavioural strategies compared to males, a difference resulting in spatial segregation by habitat. Sexual segregation in this species occurs primarily as a consequence of male avoidance by females. Studies on free‐ranging sharks provide a useful model system for examining how a predator's strategy is shaped by its environment. More theory‐based studies of the behavioural processes of sharks are required however, before critical comparisons with other vertebrate predators are possible. Suggestions for further research to address this knowledge gap are given.     

Ruffed Grouse Bonasa umbellus habitat selection in a spatially complex forest: evidence for spatial constraints on patch selection

Drumming display sites of male Ruffed Grouse Bonasa umbellus serve as activity centres and occur in a variety of forest types and age classes. We used a case‐control study design and model selection to evaluate a set of predictions about habitat constraints placed upon Grouse given the habitat where their breeding season activity centres were located. We located 110 individual Grouse activity centres near Cloquet, Minnesota, between 2002 and 2005, and 40 activity centres at two other sites in northern Minnesota in 2005. Our most parsimonious model indicated that Ruffed Grouse used logs more than other potential drumming structures (e.g. stumps, dirt mounds or roots) and sites with a higher density of shrubs as compared with unused sites. Predicted values from this model correlated with observed values from independently sampled areas. Structures used by Grouse for their drumming display were characterized by a greater density of aspen stems than unused sites when in young aspen and mature pine, but not when in other forest types. The patterns of habitat selection that we observed supported predictions (1) that the differences in habitats at larger spatial scales (e.g. forest stands or breeding territories) may impose certain constraints on specific sites selected for their drumming display, and (2) that some of these constraints may vary by forest type.     

Farmland habitat selection of wintering lesser kestrels in a Spanish pseudosteppe: implications for conservation strategies

The lesser kestrel Falco naumanni is a globally threatened species, whose breeding populations seem to have declined due to recent agricultural changes. However, nothing is known about habitat requirements during winter, despite the fact that several populations are overwintering in areas affected by agricultural transformations. We studied population size and habitat selection by wintering lesser kestrels in a Spanish pseudosteppe (Los Monegros), where traditional fallow systems for cereals are rapidly being replaced by intensive and/or irrigated crops. About 15% of the adult population wintered in the study area, as determined by systematic roadside counts compared with accurate censuses made during the breeding season. Wintering lesser kestrels preferred to forage on field margins and stubble, while avoiding abandoned fields, ploughs, scrubland, growing cereals and, mainly, the expanding irrigated crops. This work confirms the need to incorporate the habitat requirements of threatened species over their complete annual cycles; while breeding lesser kestrels scarcely use fallow (ploughed at that time), during the winter, fallow (stubble at that time) is their main foraging habitat. Both fallow land and the present agricultural calendar should be maintained to assure the conservation of wintering lesser kestrel populations.     

Predicting response to selection on a quantitative trait: a comparison between models for mixed-mating populations

Two different theoretical frameworks have been developed to predict response to selection in a mixed mating population (in which reproduction occurs by a mixture of outcrossing and self-fertilization). The genotypic covariance model (GCM) and the structured linear model (SLM) rely on the same assumptions regarding quantitative trait inheritance, but use different genetic summary statistics. Here, we demonstrate the algebraic relationships between the various genetic metrics used in each theory. This is accomplished by reformulating the GCM in terms of the Wright-Kempthorne equation. We use stochastic simulations to investigate the relative accuracy of each theory for a range of selfing rates. The SLM is generally more accurate than the GCM, the most pronounced differences emerging in simulations with inbreeding depression for fitness. In fact, with strong inbreeding depression and high selfing rates, evolution can occur opposite the direction predicted by the GCM. The simulations also indicate that direct application of random mating models to partially selfing populations can produce very inaccurate predictions if quantitative trait loci exhibit dominance.     

Environmental drivers for Coquillettidia mosquito habitat selection: a method to highlight key field factors

A crucial component for developing insect management strategies is the understanding of the ecological parameters involved in habitat selection by proliferating species. The key ecological drivers underlying habitat selection in the mosquito Coquillettidia sp. have been investigated in natura. Vegetation analysis suggested that the most suitable habitats were ponds with a high vegetation cover maintaining a high degree of humidity in the air. The optimal biotope for Coquillettidia was associated with the presence of larval host plants such as Typha sp., Phragmites sp., and Juncus sp. Water quality was also found to be a key factor in larval habitat distribution. The presence of larvae was significantly correlated with physico-chemical factors and the optimal water characteristics were neutral pH, low salt concentration, and a relatively low level of suspended particulate matter. A significant correlation was observed between chemical cues and the Coquillettidia distribution pattern. For instance, 2,6-di-tert-butyl-p-cresol was positively correlated to larval habitat, whereas high lauric acid and heptadecanoic acid concentrations may be limiting factors. This study underlines the fact that mosquito habitat selection is driven by a complex process based on discriminating levels of several ecological factors. Multivariate analysis helps understand such processes, which is this case will assist in managing expanding populations of a species that threatens human health.     

Parturient behaviour of a viviparous skink: evidence for maternal cannibalism when basking opportunity is low

We documented the behaviour of pregnant McCann’s skinks (Oligosoma maccanni) before, during and after parturition. Females were maintained in captivity from early pregnancy under thermal environments differing in basking opportunity (low, mid and high regimes). Thermal regime during pregnancy had little influence on maternal behaviours, including basking behaviour prior to birth and the duration of, and site selection for, labour. The majority of births (78%) occurred in the open and warm areas. Most females (61%; n?=?102 births, n?=?36 females) aided offspring post-birth by biting them free of the enclosing extra-embryonic membrane. Some females from the low regime consumed non-viable offspring, but whether this is a consistent difference among females held under different basking regimes requires further study. Many females (c. 79%) also exhibited a brief transient decrease in control of hind-limbs post-birth. Further studies on other squamates are recommended to shed light on the evolutionary history and possible conservation consequences of maternal behaviour during parturition.     

Death feigning as an adaptive anti‐predator behaviour: Further evidence for its evolution from artificial selection and natural populations

Death feigning is considered to be an adaptive antipredator behaviour. Previous studies on Tribolium castaneum have shown that prey which death feign have a fitness advantage over those that do not when using a jumping spider as the predator. Whether these effects are repeatable across species or whether they can be seen in nature is, however, unknown. Therefore, the present study involved two experiments: (a) divergent artificial selection for the duration of death feigning using a related species T. freemani as prey and a predatory bug as predator, demonstrating that previous results are repeatable across both prey and predator species, and (b) comparison of the death‐feigning duration of T. castaneum populations collected from field sites with and without predatory bugs. In the first experiment, T. freemani adults from established selection regimes with longer durations of death feigning had higher survival rates and longer latency to being preyed on when they were placed with predatory bugs than the adults from regimes selected for shorter durations of death feigning. As a result, the adaptive significance of death‐feigning behaviour was demonstrated in another prey–predator system. In the second experiment, wild T. castaneum beetles from populations with predators feigned death longer than wild beetles from predator‐free populations. Combining the results from these two experiments with those from previous studies provided strong evidence that predators drive the evolution of longer death feigning.     

Not all drift feeders are trout: a short review of fitness-based habitat selection models for fishes

Currently, there are few mechanistic fitness-based habitat selection models for stream fishes and most models used by management agencies focus on physical habitat alone. In this review, I describe the historical development and the status of mechanistic, fitness-based, habitat selection models for both water column (i.e., drift-feeding) and benthic stream fishes focusing on North America. Although the majority of drift feeders are not salmonids, most mechanistic habitat selection models have been developed and tested only in this group of fishes, likely due to their substantial economic importance. I review the fitness-based microhabitat selection model of Grossman et al. (Ecol Fresh Fish 11:2–10, 2002), which has been tested in both a salmonid and multiple cyprinid species. The model predicts optimal focal point velocities for drift feeders based on prey capture success–velocity relationships and does not include physiological costs, which are logistically difficult to quantify. In addition, I discuss mechanistic, fitness-based models used to predict microhabitat (i.e., patch) selection in benthic fishes. For both basic scientific and management/conservation perspectives, it is important to quantify habitat choice in fishes using mechanistic, fitness-based criteria.     

Breeding the hyperaccumulator Noccaea caerulescens for trace metal phytoextraction: first results of a pure-line selection

Abstract

To initiate the creation of phytoextraction cultivars, plants were selected from 60 populations of N. caerulescens for their high shoot biomass or Cd, Ni, and Zn concentrations. They were self-pollinated, and the selection and fixation were continued for three generations in greenhouse conditions. Selected plants showed a potential to produce 5–10 t dry matter ha^?1, which is required to decontaminate soils which have been moderately contaminated with Cd. However, the high biomass genotypes could not be fixed, probably both because of their complexity and to the sensitivity of this trait to environmental conditions, and plant density in particular. The selection led to an improvement to the Cd and Zn accumulation capacities of the plants, yet caused a decrease in their Ni accumulation. This is most likely due to a decline in Ni availability in soil, rather than to a deleterious effect of inbreeding. Metal accumulation appeared to be more heritable than biomass production and fixation for the former trait should be quicker than for the latter. The accumulation capacities of the selected plants permitted offtakes representing around 25% of the soil Cd in a single cropping. This potential has to be confirmed in field conditions.