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At least 127 records · Page 7Linked to original sources

Generic reclassification and species boundaries in the rediscovered freshwater mussel ‘Quadrula’ mitchelli (Simpson in Dall, 1896)

The Central Texas endemic freshwater mussel, Quadrula mitchelli (Simpson in Dall, 1896), had been presumed extinct until relict populations were recently rediscovered. To help guide ongoing and future conservation efforts focused on Q . mitchelli we set out to resolve several uncertainties regarding its evolutionary history, specifically its unknown generic position and untested species boundaries. We designed a molecular matrix consisting of two loci ( cytochrome c oxidase subunit I and internal transcribed spacer I ) and 57 terminal taxa to test the generic position of Q . mitchelli using Bayesian inference and maximum likelihood phylogenetic reconstruction. We also employed two Bayesian species validation methods to test five a priori species models (i.e. hypotheses of species delimitation). Our study is the first to test the generic position of Q. mitchelli and we found robust support for its inclusion in the genus Fusconaia. Accordingly, we introduce the binomial, Fusconaia mitchelli comb. nov., to accurately represent the systematic position of the species. We resolved F. mitchelli individuals in two well supported and divergent clades that were generally distinguished as distinct species using Bayesian species validation methods, although alternative hypotheses of species delineation were also supported. Despite strong evidence of genetic isolation within F. mitchelli , we do not advocate for species-level status of the two clades as they are allopatrically distributed and no morphological, behavioral, or ecological characters are known to distinguish them. These results are discussed in the context of the systematics, distribution, and conservation of F. mitchelli .

Conservation Genetics

Applied aspects of locomotion and biomechanics

Locomotion is the act and process of moving from place to place, which is fundamental to the life history of all mobile organisms. While the field of biomechanics encompasses the study of the physical constraints of what animals are capable of, ecological contexts require an integrated view that includes ecology and behavior. This chapter provides an overview of some of the areas where locomotion and biomechanics of fish movement interface with the rapidly evolving changes that humans impose on aquatic environments. These changes include fundamental alterations to the environment such as altered flows, fragmentation of riverine habitats, and invasive species, but also direct interactions that occur with capture fisheries. We explore each of these areas, considering both challenges and opportunities informed by the study of locomotion and biomechanics, emphasizing how this field can contribute to conservation of fishes in the Anthropocene. We then turn to technology, where important advances are aiding in our understanding of fish movement. In some cases those advances have themselves led to novel technologies, where biomimetic robots and related devices offer novel opportunities, both for conservation and for other pursuits.

Book chapter

Informing wetland management with waterfowl movement and sanctuary use responses to human-induced disturbance

Long-term environmental management to prevent waterfowl population declines is informed by ecology, movement behavior and habitat use patterns. Extrinsic factors, such as human-induced disturbance, can cause behavioral changes which may influence movement and resource needs, driving variation that affects management efficacy. To better understand the relationship between human-based disturbance and animal movement and habitat use, and their potential effects on management, we GPS tracked 15 dabbling ducks in California over ~4-weeks before, during and after the start of a recreational hunting season in October/November 2018. We recorded locations at 2-min intervals across three separate 24-h tracking phases: Phase 1) two weeks before the start of the hunting season (control (undisturbed) movement); Phase 2) the hunting season opening weekend; and Phase 3) a hunting weekend two weeks after opening weekend. We used GLMM models to analyze variation in movement and habitat use under hunting pressure compared with ‘normal’ observed patterns prior to commencement of hunting. We also compared responses to differing levels of disturbance related to the time of day (high - shooting/~daytime); moderate - non-lethal (~crepuscular); and low - night). During opening weekend flight (% time and distance) more than doubled during moderate and low disturbance and increased by ~50% during high disturbance compared with the pre-season weekend. Sanctuary use tripled during moderate and low disturbance and increased ~50% during high disturbance. Two weeks later flight decreased in all disturbance levels but was only less than the pre-season levels during high disturbance. In contrast, sanctuary use only decreased at night, although not to pre-season levels, while daytime doubled from ~45% to >80%. Birds adjust rapidly to disturbance and our results have implications for energetics models that estimate population food requirements. Management would benefit from reassessing the juxtaposition of essential sanctuary and feeding habitats to optimize wetland management for waterfowl.

Journal of Environmental Management

Capturing potential: Leveraging grass carp behavior Ctenopharyngodon idella for enhanced removal

Effective management of invasive species benefits from a comprehensive understanding of the species’ behavior and interactions with the invaded system. We investigated temporal dynamics of telemetry detections and the potential utility of a traitor approach for informing response efforts to the invasive grass carp ( Ctenopharyngodon idella ) population in the Sandusky River, a major tributary to Lake Erie. Telemetered grass carp exhibited heightened activity at night and early morning, suggesting that capture and removal be more effective during these time periods. Analysis of catch per unit effort (CPUE) across different removal methods, trammel nets, electrofishing, and hoop nets. suggested that incorporating the traitor approach could improve capture. Low catchability values (<0.026), based on the number of telemetered grass carp present in the river on a weekly basis and the number of those telemetered fish captured, suggest the species is difficult to capture. Optimizing response effort efficiency is important and refining catchability estimates will lessen errors in population models and improve interpretation of low CPUE data. Results from generalized additive models suggest capture could be improved using telemetry data, night removals, and by attempting exploratory removal efforts in fall and winter months. By incorporating telemetry data and acknowledging the complexities of grass carp behavior and ecology, we found that a multifaceted and data-driven approach to invasive species control could be beneficial, ultimately promoting conservation and sustainability in dynamic ecosystems like Lake Erie.

Ohio

Metamorphosis in an era of increasing climate variability

Most animals have complex life cycles including metamorphosis or other discrete life stage transitions during which individuals may be particularly vulnerable to environmental stressors. With climate change, individuals will be exposed to increasing thermal and hydrologic variability during metamorphosis, which may affect survival and performance through physiological, behavioral, and ecological mechanisms. Furthermore, because metamorphosis entails changes in traits and vital rates, it is likely to play an important role in how populations respond to increasing climate variability. To identify mechanisms underlying population responses and associated trait and life history evolution, we need new approaches to estimating changes in individual traits and performance throughout metamorphosis, and we need to integrate metamorphosis as an explicit life stage in analytical models.

Trends in Ecology & Evolution

A comprehensive multilocus phylogeny for the wood-warblers and a revised classification of the Parulidae (Aves)

The birds in the family Parulidae-commonly termed the New World warblers or wood-warblers-are a classic model radiation for studies of ecological and behavioral differentiation. Although the monophyly of a 'core' wood-warbler clade is well established, no phylogenetic hypothesis for this group has included a full sampling of wood-warbler species diversity. We used parsimony, maximum likelihood, and Bayesian methods to reconstruct relationships among all genera and nearly all wood-warbler species, based on a matrix of mitochondrial DNA (5840 nucleotides) and nuclear DNA (6 loci, 4602 nucleotides) characters. The resulting phylogenetic hypotheses provide a highly congruent picture of wood-warbler relationships, and indicate that the traditional generic classification of these birds recognizes many non-monophyletic groups. We recommend a revised taxonomy in which each of 14 genera (Seiurus, Helmitheros, Mniotilta, Limnothlypis, Protonotaria, Parkesia, Vermivora, Oreothlypis, Geothlypis, Setophaga, Myioborus, Cardellina, Basileuterus, Myiothlypis) corresponds to a well-supported clade; these nomenclatural changes also involve subsuming a number of well-known, traditional wood-warbler genera (Catharopeza, Dendroica, Ergaticus, Euthlypis, Leucopeza, Oporornis, Parula, Phaeothlypis, Wilsonia). We provide a summary phylogenetic hypothesis that will be broadly applicable to investigations of the historical biogeography, processes of diversification, and evolution of trait variation in this well studied avian group. ?? 2010 Elsevier Inc.

Molecular Phylogenetics and Evolution

Corticosterone facilitates begging and affects resource allocation in the black-legged kittiwake

Parent black-legged kittiwakes ( Rissa tridactyla ) and their dependent chicks respond to food shortages by increasing circulating levels of corticosterone. To examine the behavioral significance of corticosterone release, we experimentally increased levels of circulating corticosterone in parents and chicks up to the levels observed during food shortages. We found that corticosterone-implanted chicks begged more frequently than sham-implanted controls. Corticosterone-implanted chicks in broods of two begged more frequently than singletons. Parent kittiwakes then responded to the increase in corticosterone levels in their chicks by increasing chick-feeding rates. However, feeding rates were not different among corticosterone-implanted chicks in broods of two and singletons. We also found that corticosterone-implanted parents spent more time away from the nest—perhaps foraging—and less time brooding/guarding chicks than sham-implanted controls. Untreated mates of the corticosterone-implanted bird did not compensate for the change in their partner's behavior; consequently, chicks were left unattended about 20% of the time compared to 1% at the control nests. However, corticosterone-implanted parents did not decrease their chick-feeding rates. Our findings suggest two functional implications of the increased corticosterone secretion during food shortages in the black-legged kittiwake: it facilitates begging in chicks, and it affects time allocated by parents to guarding young at the nest. Thus, release of corticosterone might provide a mechanistic link between physiological condition and behavioral interactions among adults and their young.

Behavioral Ecology

Sources of variation in breeding-ground fidelity of mallards (Anas platyrhynchos)

Generalizations used to support hypotheses about the evolution of fidelity to breeding areas in birds include the tendency for fidelity to be greater in adult birds than in yearlings. In ducks, in contrast to most bird species, fidelity is thought to be greater among females than males. Researchers have suggested that fidelity in ducks is positively correlated with pond availability. However, most estimates of fidelity on which these inferences have been based represent functions of survival and recapture-resighting probabilities in addition to fidelity. We applied the modeling approach developed by Burnham to recapture and band recovery data of mallard ducks to test the above hypotheses about fidelity. We found little evidence of sex differences in adult philopatry, with females being slightly more philopatric than males in one study area, but not in a second study area. However, yearling females were more philopatric than yearling males in both study areas. We found that adults were generally more philopatric than yearlings. We could find no relationship between fidelity and pond availability. Our results, while partially supporting current theory concerning sex and age differences in philopatry, suggest that adult male mallards are more philopatric than once thought, and we recommend that other generalizations about philopatry be revisited with proper estimation techniques.

Behavioral Ecology

Ephemeral lekking behavior in the buff-breasted sandpiper, Tryngites subruficollis

We studied male reproductive behavior of the buff-breasted sandpiper Tryngites subruficoills for three yean on a 16-km 2 study site in northern Alaska to document variation in male lekking behavior and to explore the causes of that variation. During the breeding season, about 75% of males on the study area displayed on leks, with the remainder displaying solitarily. Leks averaged between 2.3 and 3.0 males each (maximum size = 20). Most leks (69%) were present in only one year and about one-tenth were active all three years. Half of the leks were active for only one survey (maximum of 3-4 days) in a given year. Individual male behavior varied substantially, from remaining at a tingle lek for most of the breeding season or attending multiple leks during the season, to displaying solitarily or displaying both on leks and solitarily. Some males (30% or fewer) displayed near nests during the later part of the breeding season, perhaps attempting to copulate with females during egg-laying. The pro-portion of males that displayed on leks remained consistently high throughout the breeding season despite changes in the operational sex ratio and in the intensity of male-male competition. However, the absolute number of males (lekking and solitary) in the study area was positively correlated with the number of fertile females during both breeding seasons. We suggest that buff-breasted sandpipers may be unusual among lek-breeding birds in that males have the option of leaving areas when the number of fertile females becomes depressed and flying to new areas where breeding opportunities are still available. Breeding opportunities may be especially variable in the high arctic because of uneven snow accumulation and differential melt-off that can delay breeding by two or more weeks. This interpretation suggests that the mating system of the buff-breasted sandpiper must be viewed at a much larger scale than what has typically been used in mating system studies.

Alaska

Breeding synchrony and extrapair fertilizations in two populations of red-winged blackbirds

We tested the relationship between synchrony of breeding and the frequency of extrapair fertilizations (EPFs) in two populations of red-winged blackbirds known to differ in female extrapair behavior. We found no association between the number of simultaneously fertilizable females (temporal neighbors) and EPF rate in either population, although a significant difference between populations in the direction of this relationship (positive where females initiated extrapair copulations and negative where males initiated them) suggested a modest difference in the influence of synchrony. Males losing offspring to EPFs tended to have more fertilizable females at that time than the actual sires in some analyses but not in others. We also tested several assumptions underlying two competing hypotheses for the effects of synchrony. We found no evidence that females pursued extrapair copulations more often when other females were synchronous. Rather, females were more likely to gain EFFs with exirapatr males whose social mates were not yet building their nests. Synchrony also did not consistently affect male pursuit of exirapair copulations or achievement of EPFs. These results suggest that timing of breeding has some effects on extrapair activity, but that those effects are both relatively weak and influenced by other factors that vary between years or populations.

Behavioral Ecology

Geographic variation in dispersal of western burrowing owl (Athene cunicularia hypugaea) populations across North America

Dispersal is one of the key elements of species’ metapopulation dynamics and, hence, influences global conservation status. Furthermore, determining the geographic variation in magnitude and direction of dispersal throughout a species’ distribution may expand our understanding of the causes of population declines in species of conservation concern. For instance, western burrowing owl ( Athene cunicularia hypugaea ) populations have declined at the northern and eastern edge of their breeding distribution during the 20th century. In the same period, large areas of thornscrub that did not support breeding owls were converted to irrigated agriculture in the southern edge of the subspecies’ breeding distribution in northwestern Mexico. These farmlands now support some of the highest breeding densities of owls. We tested the hypothesis that owls that colonized this recently created habitat originated from declining migratory populations from the northern portion of the subspecies’ range. We used stable isotopes 2 H, 13 C, and 15 N in owl feathers to infer breeding dispersal patterns throughout the subspecies’ breeding range. Populations near the northern edge of the subspecies’ breeding range had immigrants that dispersed over larger distances than immigrants at low and mid latitude populations. However, agricultural populations in northwestern Mexico disrupted this latitudinal pattern, attracting owls from more distant locations. We also found immigrants originated from further distances in declining populations than increasing populations. Stable isotopes provided no evidence of contemporaneous breeding dispersal from Canadian populations to northwestern Mexico but suggest that agricultural areas in the southern edge of the subspecies’ distribution have altered the continental dispersal pattern.

Behavioral Ecology

Many avenues for spatial personality research: a response to comments on Stuber et al. (2022)

We are grateful for the thought-provoking and forward-looking commentaries ( Dingemanse et al. 2022 ; Mabry 2022 ; Spiegel and Pinter-Wollman 2022 ; Vander Wal et al. 2022 ) in response to our meta-analysis of evidence for consistent among-individual differences in animals’ spatial behaviors ( Stuber et al. 2022 ). A clear consensus is that our demonstration of the prevalence of repeatability across spatial behaviors, and taxa, is only the first step towards identifying the mechanisms and consequences of variation in spatial behavior. Here, we take the opportunity to emphasize key future directions pertaining to uncovering mechanisms, disentangling apparent personality from spatial constraints, and examining additional metrics of variation.

Behavioral Ecology

Helpers show plasticity in their responses to breeder turnover

Nonbreeding helpers can greatly improve the survival of young and the reproductive fitness of breeders in many cooperatively breeding species. Breeder turnover, in turn, can have profound effects on dispersal decisions made by helpers. Despite its importance in explaining group size and predicting the population demography of cooperative breeders, our current understanding of how individual traits influence animal behavior after disruptions to social structure is incomplete particularly for terrestrial mammals. We used 12 yr of genetic sampling and group pedigrees of gray wolves ( Canis lupus ) in Idaho, USA, to ask questions about how breeder turnover affected the apparent decisions by mature helpers (≥2-yr-old) to stay or leave a group over a 1-yr time interval. We found that helpers showed plasticity in their responses to breeder turnover. Most notably, helpers varied by sex and appeared to base dispersal decisions on the sex of the breeder that was lost as well. Male and female helpers stayed in a group slightly more often when there was breeder turnover of the same sex, although males that stayed were often recent adoptees in the group. Males, however, appeared to remain in a group less often when there was breeding female turnover likely because such vacancies were typically filled by related females from the males’ natal group (i.e. inbreeding avoidance). We show that helpers exploit instability in the breeding pair to secure future breeding opportunities for themselves. The confluence of breeder turnover, helper sex, and dispersal and breeding strategies merge to influence group composition in gray wolves.

Idaho

Causes of differential migration distance: Test of seven mechanistic hypotheses in an arctic raptor

Exploring the causes of differential migration, or variation in migration distance, has increased our understanding of the remarkable variation in migratory behavior exhibited by birds more generally. However, considerable uncertainty exists regarding the mechanisms underlying differential migration distance in birds despite it being a common phenomenon. We leveraged migration distances from GPS-tracked rough-legged hawks Buteo lagopus to test predictions deduced from seven hypotheses proposed to explain the underlying cause(s) of differential migration distance. We provide the first empirical evidence in support of a social dominance food maximization hypothesis whereby dominant individuals migrate to higher quality nonbreeding locations with respect to foraging efficiency regardless of migration distance. Within females, larger more dominant individuals migrated intermediate distances while smaller, subordinate individuals migrated both longer and shorter distances. We also found support for the social dominance distance minimization hypothesis because more aggressive females migrated shorter distances, although increased aggression at shorter distances may be a consequence of poor body condition. Within males, we found some support for the fasting endurance and thermal tolerance hypotheses because body size was negatively correlated with migration distance. Body size was also negatively correlated with food availability and winter minimum temperatures within both sexes, providing additional mechanistic support for the fasting endurance and thermal tolerance hypotheses. Overall, our results suggest differential migration distance within rough-legged hawks is caused by a combination of competition for nonbreeding resources and constraints on fasting endurance or thermal tolerance, but is unrelated to competition for breeding opportunities, dietary preferences, or flight efficiency.

Behavioral Ecology

Growth, movement, and survival of precocial shorebird chicks are constrained by their environment.

Young animals are often less mobile than adults, while also having high energetic demands. They may therefore be more vulnerable to local-scale changes in environmental conditions. In particular, when 1 sex must grow more rapidly than the other to achieve a larger adult size, that sex may experience especially dramatic reductions in growth and survival in the face of suboptimal environmental conditions. In order to investigate the flexibility of individuals in response to local-scale environmental variation during development, we studied the sex-specific growth, movement, and survival of Hudsonian Godwit ( Limosa haemastica ) chicks—a sexually dimorphic, precocial shorebird that breeds in the sub-Arctic and exhibits a male-skewed adult sex ratio. We found that female chicks—which must grow to a larger adult size—reached their maximum growth rates at a later age, but had similar growth rates to males before that and survived equally well to 21 days. We also found that, irrespective of sex, chicks had reduced movement rates when they were young and/or temperatures were cold, and only weakly increased their movement rates when invertebrate abundances remained low across an entire week. Early in life, godwit chicks may therefore be constrained from increasing their foraging efforts by local environmental conditions, forcing females to sustain higher growth rates late in the season past the local resource peak. Such sex-specific vulnerabilities could lead to lower early-life survival and, in turn, skewed adult sex ratios, which have important implications for population dynamics and persistence.

Behavioral Ecology

Host social behavior and parasitic infection: A multifactorial approach

I examined associations between several components of host social organization, including group size and gregariousness, group stability, territoriality and social class, and gastrointestinal parasite load in African bovids. At an intraspecific level, group size was positively correlated with parasite prevalence, but only when the parasite was relatively host specific and only among host species living in stable groups. Social class was also an important predictor of infection rates. Among gazelles, territorial males had higher parasite intensities than did either bachelor males or females and juveniles, suggesting that highly territorial individuals may be either more exposed or more susceptible to parasites. Associations among territoriality, grouping, and parasitism were also found across taxa. Territorial host genera were more likely to be infected with strongyle nematodes than were nonterritorial hosts, and gregarious hosts were more infected than were solitary hosts. Analyses also revealed that gregariousness and territoriality had an interactive effect on individual parasite richness, whereby hosts with both traits harbored significantly more parasite groups than did hosts with only one or neither trait. Overall, study results indicate that multiple features of host social behavior influence infection risk and suggest that synergism between traits also has important effects on host parasite load.

Behavioral Ecology

The adaptive significance of stealing in a marine bird and its relationship to parental quality

Kleptoparasitism (food theft) is a tactic used opportunistically by many foraging birds, but little is known about its fitness benefits. Here we show that habitual kleptoparasitism by individual parent roseate terns (Sterna dougallii) is associated with consistently superior reproductive performance relative to nonkleptoparasitic ('honest') parents, as measured by growth and survival to fledging among their offspring. In broods of two, both chicks of kleptoparasitic parents exhibited superior growth performance during the middle and later stages of the rearing period, relative to chicks of honest parents. This difference was especially pronounced in second-hatched chicks, whose survival is highly variable among years and dependent on food availability. Over a 10-year period, average productivity (number of chicks fledged per pair) was significantly higher among kleptoparasites than among honest parents, with a larger relative difference during years of food shortage. Our study indicates that kleptoparasitism in roseate terns is an important component of parental quality and provides the first evidence that food stealing is associated with enhanced fitness in a facultatively kleptoparasitic seabird.

Behavioral Ecology