Successful Colonization of a Novel Urban Environment is Associated with an Urban Behavioural Syndrome in a Reed‐Nesting Waterbird

Urbanization is currently considered one of the most rapid types of global environmental change. More and more wildlife species are subject to increasing anthropogenic disturbance, but only some of them adapt to become successful urban exploiters. Although a number of fixed life history characteristics may enhance population persistence in an urbanized landscape, behavioural traits are thought to be critical for colonization of a novel urban environment. Within the class of birds, behavioural responses to urban environment have been assessed mostly for passerine species. Here, I examined behavioural alterations in a recently founded urban population of a reed‐nesting rallid species, the Eurasian coot Fulica atra. I found that urban coots adapted to nest in anthropogenically transformed littoral zones with scarce or no emergent vegetation, which precluded efficient nest concealment. Despite this, urban individuals spent, on average, less time incubating due to more frequent bouts off the nest than suburban conspecifics. This pattern was likely possible due to the relaxation of predation pressure in the colonized urban environment. Urban birds were also more aggressive, approached a human intruder at the nest more closely and were more likely to actively defend their nests. Finally, they had a reduced level of physiological stress (as measured with heterophil/lymphocyte ratio) when compared with suburban individuals. In conclusion, the behaviour of coots from the recently founded urban population was consistent with behavioural syndromes found in typical urban exploiters. The results support the central role of behavioural adaptation in successful colonization of novel environments by wildlife.     

Progressively excluding mammals of different body size affects community and trait structure of ground beetles

Mammalian grazing induces changes in vegetation properties in grasslands, which can affect a wide variety of other animals including many arthropods. However, the impacts may depend on the type and body size of these mammals. Furthermore, how mammals influence functional trait syndromes of arthropod communities is not well known. We progressively excluded large (e.g. red deer, chamois), medium (e.g. alpine marmot, mountain hare), and small (e.g. mice) mammals using size‐selective fences in two vegetation types (short‐ and tall‐grass vegetation) of subalpine grasslands. We then assessed how these exclusions affected the community composition and functional traits of ground beetles (Coleoptera, Carabidae), and which vegetation characteristic mediated the observed effects. Total carabid biomass, the activity densities of carabids with specific traits (i.e. small eyes, short wings), the richness of small‐eyed species and the richness of herbivorous species were significantly higher when certain mammals were excluded compared to when all mammals had access, regardless of vegetation type. Excluding large and medium mammals increased the activity density of herbivorous carabid species, but only in short‐grass vegetation. Similarly, excluding large mammals (ungulates) altered carabid species composition in the short‐, but not in the tall‐grass vegetation. All these responses were related to aboveground plant biomass, but not to plant Shannon diversity or vegetation structural heterogeneity. Our results indicate that changes in aboveground plant biomass are key drivers of mammalian grazers’ influence on carabids, suggesting that bottom–up forces are important in subalpine grassland systems. The exclusion of ungulates provoked the strongest carabid response. Our results, however, also highlight the ecological significance of smaller herbivorous mammals. Our study furthermore shows that mammalian grazing not only altered carabid community composition, but also caused community‐wide functional trait shifts, which could potentially have a wider impact on species interactions and ecosystem functioning.     

Blow flies as urban wildlife sensors

Wildlife detection in urban areas is very challenging. Conventional monitoring techniques such as direct observation are faced with the limitation that urban wildlife is extremely elusive. It was recently shown that invertebrate‐derived DNA (iDNA) can be used to assess wildlife diversity in tropical rainforests. Flies, which are ubiquitous and very abundant in most cities, may also be used to detect wildlife in urban areas. In urban ecosystems, however, overwhelming quantities of domestic mammal DNA could completely mask the presence of wild mammal DNA. To test whether urban wild mammals can be detected using fly iDNA, we performed DNA metabarcoding of pools of flies captured in Berlin, Germany, using three combinations of blocking primers. Our results show that domestic animal sequences are, as expected, very dominant in urban environments. Nevertheless, wild mammal sequences can often be retrieved, although they usually only represent a minor fraction of the sequence reads. Fly iDNA metabarcoding is therefore a viable approach for quick scans of urban wildlife diversity. Interestingly, our study also shows that blocking primers can interact with each other in ways that affect the outcome of metabarcoding. We conclude that the use of complex combinations of blocking primers, although potentially powerful, should be carefully planned when designing experiments.     

Behavioural responses of wildlife to urban environments

Increased urbanization represents a formidable challenge for wildlife. Nevertheless, a few species appear to thrive in the evolutionarily novel environment created by cities, demonstrating the remarkable adaptability of some animals. We argue that individuals that can adjust their behaviours to the new selection pressures presented by cities should have greater success in urban habitats. Accordingly, urban wildlife often exhibit behaviours that differ from those of their rural counterparts, from changes to food and den preferences to adjustments in the structure of their signals. Research suggests that behavioural flexibility (or phenotypic plasticity) may be an important characteristic for succeeding in urban environments. Moreover, some individuals or species might possess behavioural traits (a particular temperament) that are inherently well suited to occupying urban habitats, such as a high level of disturbance tolerance. This suggests that members of species that are less ‘plastic’ or naturally timid in temperament are likely to be disadvantaged in high‐disturbance environments and consequently may be precluded from colonizing cities and towns.     

Persistence of vigilance and flight response behaviour in wild reindeer with varying domestic ancestry

Knowledge about changes in behavioural traits related to wildness and tameness is for most mammals lacking, despite the increased trend of using domestic stock to re‐establish wild populations into historical ranges. To test for persistence of behavioural traits of wild reindeer (Rangifer tarandus L.) exposed to hunting, we sampled DNA, vigilance and flight responses in wild reindeer herds with varying domestic ancestry. Analyses of 14 DNA microsatellite loci revealed a dichotomous main genetic structure reflecting their native origin, with the Rondane reindeer genetically different from the others and with least differentiation towards the Hardangervidda reindeer. The genetic clustering of the reindeer in Norefjell‐Reinsjøfjell, Ottadalen and Forollhogna, together with domestic reindeer, supports a predominant domestic origin of these herds. Despite extensive hunting in all herds, the behavioural measures indicate increasing vigilance, alert and flight responses with increasing genetic dissimilarity with domestic herds. Vigilance frequency and time spent vigilant were higher in Rondane compared to Hardangervidda, which again were higher than herds with a domestic origin. We conclude that previous domestication has preserved a hard wired behavioural trait in some reindeer herds exhibiting less fright responses towards humans that extensive hunting has, but only slightly, altered. This brings novel and relevant knowledge to discussions about genetic diversity of wildlife in general and wild reindeer herds in Norway in specific.     

Extremotolerance in fungi: evolution on the edge

Our planet offers many opportunities for life on the edge: high and low temperatures, high salt concentrations, acidic and basic conditions and toxic environments, to name but a few extremes. Recent studies have revealed the diversity of fungi that can occur in stressful environments that are hostile to most eukaryotes. We review these studies here, with the additional purpose of proposing some mechanisms that would allow for the evolutionary adaptation of eukaryotic microbial life under extreme conditions. We focus, in particular, on life in ice and life at high salt concentrations, as there is a surprising similarity between the fungal populations in these two kinds of environments, both of which are characterized by low water activity. We propose steps of evolution of generalist species towards the development of specialists in extreme habitats. We argue that traits present in some fungal groups, such as asexuality, synthesis of melanin-like pigments and a flexible morphology, are preadaptations that facilitate persistence and eventual adaptation to conditions on the ecological edge, as well as biotope switches. These processes are important for understanding the evolution of extremophiles; moreover, they have implications for the emergence of novel fungal pathogens.     

Environmental variation is a major predictor of global trait turnover in mammals

Aim

To evaluate how environment and evolutionary history interact to influence global patterns of mammal trait diversity (a combination of 14 morphological and life‐history traits).

Location

The global terrestrial environment.

Taxon

Terrestrial mammals.

Methods

We calculated patterns of spatial turnover for mammalian traits and phylogenetic lineages using the mean nearest taxon distance. We then used a variance partitioning approach to establish the relative contribution of trait conservatism, ecological adaptation and clade specific ecological preferences on global trait turnover.

Results

We provide a global scale analysis of trait turnover across mammalian terrestrial assemblages, which demonstrates that phylogenetic turnover by itself does not predict trait turnover better than random expectations. Conversely, trait turnover is consistently more strongly associated with environmental variation than predicted by our null models. The influence of clade‐specific ecological preferences, reflected by the shared component of phylogenetic turnover and environmental variation, was considerably higher than expectations. Although global patterns of trait turnover are dependent on the trait under consideration, there is a consistent association between trait turnover and environmental predictive variables, regardless of the trait considered.

Main conclusions

Our results suggest that changes in phylogenetic composition are not always coupled with changes in trait composition on a global scale and that environmental conditions are strongly associated with patterns of trait composition across species assemblages, both within and across phylogenetic clades.     

Nesting and acoustic ecology,but not phylogeny,influence passerine urban tolerance

Urbanization is one of the most extensive and ecologically significant changes happening to terrestrial environments, as it strongly affects the distribution of biodiversity. It is well established that native species richness is reduced in urban and suburban areas, but the species traits that predict tolerance to urbanization are yet little understood. In birds, one of the most studied groups in this respect, evidence is appearing that acoustic traits influence urban living, but it remains unknown how this compares to the effects of more obvious ecological traits that facilitate urban living. Therefore, it remains unclear whether acoustic communication is an important predictor of urban tolerance among species. Here, with a comparative study across 140 European and North American passerines, I show that high song frequency, which is less masked by the low‐frequency anthropogenic noise, is associated with urban tolerance, with an effect size over half that of the most important ecological trait studied: off‐ground nesting. Other nesting and foraging traits accepted to facilitate urban living did not differ for species occurring in urban environments. Thus, the contribution of acoustic traits for passerine urban tolerance approximates that of more obvious ecological traits. Nonetheless, effect sizes of the biological predictors of urban tolerance were low and the phylogenetic signal for urban tolerance was null, both of which suggest that factors other than phenotypic traits have major effects on urban tolerance. A simple possibility is exposure to urbanization, as there was a higher proportion of urban‐tolerant species in Europe, which is more urbanized than North America.     

Beyond the landscape: Resistance modelling infers physical and behavioural gene flow barriers to a mobile carnivore across a metropolitan area

Urbanization affects key aspects of wildlife ecology. Dispersal in urban wildlife species may be impacted by geographical barriers but also by a species’ inherent behavioural variability. There are no functional connectivity analyses using continuous individual‐based sampling across an urban‐rural continuum that would allow a thorough assessment of the relative importance of physical and behavioural dispersal barriers. We used 16 microsatellite loci to genotype 374 red foxes (Vulpes vulpes) from the city of Berlin and surrounding rural regions in Brandenburg in order to study genetic structure and dispersal behaviour of a mobile carnivore across the urban‐rural landscape. We assessed functional connectivity by applying an individual‐based landscape genetic optimization procedure. Three commonly used genetic distance measures yielded different model selection results, with only the results of an eigenvector‐based multivariate analysis reasonably explaining genetic differentiation patterns. Genetic clustering methods and landscape resistance modelling supported the presence of an urban population with reduced dispersal across the city border. Artificial structures (railways, motorways) served as main dispersal corridors within the cityscape, yet urban foxes avoided densely built‐up areas. We show that despite their ubiquitous presence in urban areas, their mobility and behavioural plasticity, foxes were affected in their dispersal by anthropogenic presence. Distinguishing between man‐made structures and sites of human activity, rather than between natural and artificial structures, is thus essential for better understanding urban fox dispersal. This differentiation may also help to understand dispersal of other urban wildlife and to predict how behaviour can shape population genetic structure beyond physical barriers.     

Candidate gene polymorphisms for behavioural adaptations during urbanization in blackbirds

Successful urban colonization by formerly rural species represents an ideal situation in which to study adaptation to novel environments. We address this issue using candidate genes for behavioural traits that are expected to play a role in such colonization events. We identified and genotyped 16 polymorphisms in candidate genes for circadian rhythms, harm avoidance and migratory and exploratory behaviour in 12 paired urban and rural populations of the blackbird Turdus merula across the Western Palaearctic. An exonic microsatellite in the SERT gene, a candidate gene for harm avoidance behaviour, exhibited a highly significant association with habitat type in an analysis conducted across all populations. Genetic divergence at this locus was consistent in 10 of the 12 population pairs; this contrasts with previously reported stochastic genetic divergence between these populations at random markers. Our results indicate that behavioural traits related to harm avoidance and associated with the SERT polymorphism experience selection pressures during most blackbird urbanization events. These events thus appear to be influenced by homogeneous adaptive processes in addition to previously reported demographic founder events.     

Plasticity and evolution in correlated suites of traits

When organisms are faced with new or changing environments, a central challenge is the coordination of adaptive shifts in many different phenotypic traits. Relationships among traits may facilitate or constrain evolutionary responses to selection, depending on whether the direction of selection is aligned or opposed to the pattern of trait correlations. Attempts to predict evolutionary potential in correlated traits generally assume that correlations are stable across time and space; however, increasing evidence suggests that this may not be the case, and flexibility in trait correlations could bias evolutionary trajectories. We examined genetic and environmental influences on variation and covariation in a suite of behavioural traits to understand if and how flexibility in trait correlations influences adaptation to novel environments. We tested the role of genetic and environmental influences on behavioural trait correlations by comparing Trinidadian guppies (Poecilia reticulata) historically adapted to high‐ and low‐predation environments that were reared under native and non‐native environmental conditions. Both high‐ and low‐predation fish exhibited increased behavioural variance when reared under non‐native vs. native environmental conditions, and rearing in the non‐native environment shifted the major axis of variation among behaviours. Our findings emphasize that trait correlations observed in one population or environment may not predict correlations in another and that environmentally induced plasticity in correlations may bias evolutionary divergence in novel environments.     

The behavioural ecology and population dynamics of a cryptic ground‐dwelling mammal in an urban Australian landscape

Urbanization results in widespread habitat loss and fragmentation and generally has a negative impact upon native wildlife, in particular ground‐dwelling mammals. The northern brown bandicoot (Isoodon macrourus; Marsupialia: Peramelidae) is one of relatively few native Australian ground‐dwelling mammals that is able to survive within urbanized landscapes. As a consequence of extensive clearing and urban development within the city of Brisbane, bandicoots are now restricted to the mostly small (<10 ha) bushland fragments scattered across the city landscape. Our study examined the behavioural ecology of northern brown bandicoots within habitat fragments located on a major creek‐line, using mark‐recapture population monitoring and radio telemetry. Bandicoots at monitored sites were found to occur at high densities (typically one individual ha^?1), although one‐third of the populations were transient. Radio tracking revealed that bandicoots had relatively small home ranges (mean 1.5 ± 0.2 ha) comprised largely of bushland/grassland with dense, often weed‐infested ground cover. Bandicoots sheltered by day in these densely covered areas and also spent most time foraging there at night, although they occasionally ventured small distances to forage in adjacent maintained parklands and residential lawns. We suggest that introduced tall grasses and other weeds contribute to high habitat quality within riparian habitat fragments and facilitate the persistence of high density populations, comprised of individuals with small home ranges. The generalized dietary and habitat requirements of northern brown bandicoots, as well as a high reproductive output, undoubtedly facilitate the survival of the species in urban habitat fragments. Further research is required on other native mammal species in urbanized landscapes to gain a greater understanding of how best to conserve wildlife in these heavily modified environments.     

Female mate choice of male signals is unlikely to promote ecological adaptation in Enchenopa treehoppers (Hemiptera: Membracidae)

A key question in speciation research is how ecological and sexual divergence arise and interact. We tested the hypothesis that mate choice causes local adaptation and ecological divergence using the rationale that the performance~signal trait relationship should parallel the attractiveness~signal trait relationship. We used female fecundity as a measure of ecological performance. We used a species in the Enchenopa binotata treehopper complex, wherein speciation involves adaptation to novel environments and divergence in sexual communication. We used a full‐sibling, split‐family rearing design to estimate genetic correlations (r_G) between fecundity and signal traits, and compared those relationships against population‐level mate preferences for the signal traits. Animal model estimates for r_G between female fecundity and male signal traits overlapped zero—rejecting the hypothesis—but could reflect sample size limitations. The magnitude of r_G correlated with the strength of the mate preferences for the corresponding signal traits, especially for signal frequency, which has the strongest mate preference and the most divergence in the complex. However, signal frequencies favored by the population‐level mate preference are not associated with high fecundity. Therefore, mate preferences do not appear to have been selected to favor high‐performance genotypes. Our findings suggest that ecological and sexual divergence may arise separately, but reinforce each other, during speciation.     

Functional trait changes in the floras of 11 cities across the globe in response to urbanization

Urbanization causes major environmental changes globally, which can potentially homogenize biota across cities through the loss and gain of particular types of species. We examine whether urban environments consistently select for plants with particular traits and the implications of such changes on the functional composition of urban floras. We classified plant recorded in 11 cities around the globe as species that have either colonized (arrived and naturalized), persisted or been lost (local extirpation) following urbanization. We analyzed how 10 traits previously linked with plant responses to environmental conditions explained membership of these three groups, by comparing colonisers with persistent and extirpated plants through individual city‐level Bayesian models. Then, we used meta‐analysis to assess consistency of traits across urban areas. Finally, we explored several possible scenarios of functional change using these results. On average, urban colonizers had heavier seeds, unspecialised nutrient requirements, were taller and were annual species more often, especially when compared to locally extirpated plants. Common trends of functional change in urban plant communities include shifts towards taller and heavier‐seeded plants, and an increased prevalence of the short‐lived species, and plants without mutualistic nutritional strategies. Our results suggest that plant traits influence the species that succeed in urban environments worldwide. Different species use different ecological strategies to live in urban environments, as suggested by the importance of several traits that may appear as trait constellations. Plant height and seed mass were the only traits associated with both colonizer and extirpated plant status in urban environments. Based on our data, predicting colonization in urban environments may be easier than identifying extirpation‐prone plants; albeit some regional variation, colonization seems strongly driven by environmental conditions common to most cities (e.g. altered disturbance regimes), whereas extirpation may depend more on processes that vary across cities.     

Effects of freshwater eutrophication on species and functional beta diversity of periphytic algae

Studies about beta diversity and environmental heterogeneity have shown that the strength of the environmental filtering effect may decrease with the increasing scale. These empirical results have related eutrophic aquatic environments to higher values of beta diversity, but never to dissimilarity of species and functional traits of periphytic algae. We tested the hypotheses that periphytic algae have higher dissimilarity of both species and functional traits in eutrophic environments, and that these dissimilarities are related to environmental dissimilarity. To this end, we used richness, density, and four functional traits of periphytic algae and local limnological data from wetlands in the Brazilian savanna (Cerrado). We analyzed the beta diversity and the relationship of species and functional dissimilarities with the environmental dissimilarity and geographic distances. Our hypothesis was confirmed for functional traits dissimilarity and for the importance of the environmental dissimilarity for both species and functional beta diversity. The cultural eutrophication led to a functional homogenization in urban wetlands, which indicates the establishment of species with similar ecological requirements, and consequently, similar ‘roles’ in the ecosystem, and also that sensitive species may have been replaced by tolerant species, leading to declining biodiversity.

     

Large‐brained mammals live longer

Many mammals have brains substantially larger than expected for their body size, but the reasons for this remain ambiguous. Enlarged brains are metabolically expensive and require elongated developmental periods, and so natural selection should have favoured their evolution only if they provide counterbalancing advantages. One possible advantage is facilitating the construction of behavioural responses to unusual, novel or complex socio‐ecological challenges. This buffer effect should increase survival rates and favour a longer reproductive life, thereby compensating for the costs of delayed reproduction. Here, using a global database of 493 species, we provide evidence showing that mammals with enlarged brains (relative to their body size) live longer and have a longer reproductive lifespan. Our analysis supports and extends previous findings, accounting for the possible confounding effects of other life history traits, ecological and dietary factors, and phylogenetic autocorrelation. Thus, these findings provide support for the hypothesis that mammals counterbalance the costs of affording large brains with a longer reproductive life.     

Fine‐scale variation within urban landscapes affects marking patterns and gastrointestinal parasite diversity in red foxes

1. Urban areas are often considered to be a hostile environment for wildlife as they are highly fragmented and frequently disturbed. However, these same habitats can contain abundant resources, while lacking many common competitors and predators. The urban environment can have a direct impact on the species living there but can also have indirect effects on their parasites and pathogens. To date, relatively few studies have measured how fine‐scale spatial heterogeneity within urban landscapes can affect parasite transmission and persistence.
2. Here, we surveyed 237 greenspaces across the urban environment of Edinburgh (UK) to investigate how fine‐scale variation in socio‐economic and ecological variables can affect red fox (Vulpes vulpes) marking behavior, gastrointestinal (GI) parasite prevalence, and parasite community diversity.
3. We found that the presence and abundance of red fox fecal markings were nonuniformly distributed across greenspaces and instead were dependent on the ecological characteristics of a site. Specifically, common foraging areas were left largely unmarked, which indicates that suitable resting and denning sites may be limiting factor in urban environments. In addition, the amount of greenspace around each site was positively correlated with overall GI parasite prevalence, species richness, and diversity, highlighting the importance of greenspace (a commonly used measure of landscape connectivity) in determining the composition of the parasite community in urban areas.
4. Our results suggest that fine‐scale variation within urban environments can be important for understanding the ecology of infectious diseases in urban wildlife and could have wider implication for the management of urban carnivores.

     

Anthropogenic environments exert variable selection on cranial capacity in mammals

It is thought that behaviourally flexible species will be able to cope with novel and rapidly changing environments associated with human activity. However, it is unclear whether such environments are selecting for increases in behavioural plasticity, and whether some species show more pronounced evolutionary changes in plasticity. To test whether anthropogenic environments are selecting for increased behavioural plasticity within species, we measured variation in relative cranial capacity over time and space in 10 species of mammals. We predicted that urban populations would show greater cranial capacity than rural populations and that cranial capacity would increase over time in urban populations. Based on relevant theory, we also predicted that species capable of rapid population growth would show more pronounced evolutionary responses. We found that urban populations of two small mammal species had significantly greater cranial capacity than rural populations. In addition, species with higher fecundity showed more pronounced differentiation between urban and rural populations. Contrary to expectations, we found no increases in cranial capacity over time in urban populations—indeed, two species tended to have a decrease in cranial capacity over time in urban populations. Furthermore, rural populations of all insectivorous species measured showed significant increases in relative cranial capacity over time. Our results provide partial support for the hypothesis that urban environments select for increased behavioural plasticity, although this selection may be most pronounced early during the urban colonization process. Furthermore, these data also suggest that behavioural plasticity may be simultaneously favoured in rural environments, which are also changing because of human activity.     

Spinal cord regeneration: Lessons for mammals from non‐mammalian vertebrates

Unlike mammals, regenerative model organisms such as amphibians and fish are capable of spinal cord regeneration after injury. Certain key differences between regenerative and nonregenerative organisms have been suggested as involved in promoting this process, such as the capacity for neurogenesis and axonal regeneration, which appear to be facilitated by favorable astroglial, inflammatory and immune responses. These traits provide a regenerative‐permissive environment that the mammalian spinal cord appears to be lacking. Evidence for the regenerative nonpermissive environment in mammals is given by the fact that they possess neural stem/progenitor cells, which transplanted into permissive environments are able to give rise to new neurons, whereas in the nonpermissive spinal cord they are unable to do so. We discuss the traits that are favorable for regeneration, comparing what happens in mammals with each regenerative organism, aiming to describe and identify the key differences that allow regeneration. This comparison should lead us toward finding how to promote regeneration in organisms that are unable to do so. genesis 51:529–544. © 2013 Wiley Periodicals, Inc.     

Community functional trait composition at the continental scale: the effects of non‐ecological processes

Ecological communities and their response to environmental gradients are increasingly being described by measures of trait composition at the community level – the trait‐based approach. Whether ecological or non‐ecological processes influence trait composition between communities has been debated. Understanding the processes that influence trait composition is important for reconstructing paleoenvironmental conditions from fossil deposits and for understanding changes in community functionality through time. Here, we assess the influence of ecological and non‐ecological processes on the distribution of traits within North American mammals. We found that non‐ecological processes including historical contingency, spatial autocorrelation, and evolutionary history do not influence trait composition; however, the variance in trait composition is highly explained by climate gradients. Our results suggest that habitat breadth, terrestriality, diet breadth, and reproductive traits are strong candidates as proxies for measuring functional aspects of environments in the past and present.