• Home
  • H. Martin Schaefer
H. Martin Schaefer

H. Martin Schaefer
Fundación Jocotoco, Quito, Ecuador

PhD

About

304
Publications
46,144
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
8,268
Citations

Publications

Publications (304)
Preprint
Full-text available
Land-use intensification has contrasting effects on different ecosystem services, often leading to land-use conflicts. Multiple studies, especially within the ‘land-sharing versus land-sparing’ debate, have demonstrated how landscape-scale strategies can minimise the trade-off between agricultural production and biodiversity conservation. However,...
Article
Prevalence responses to anthropic factors differ across hosts and parasite species. We here analyzed the spatiotemporal variation of avian haemosporidian prevalence in bird assemblages of the Mooswald forest (i.e., urban greenspace; Freiburg, Germany), in response to local environmental features (e.g., water sources, human presence (visited)/absenc...
Article
Prevalence responses to anthropic factors differ across hosts and parasite species. We here analyzed the spatiotemporal variation of avian haemosporidian prevalence in bird assemblages of the Mooswald forest (i.e., urban greenspace; Freiburg, Germany), in response to local environmental features (e.g., water sources, human presence (visited)/absenc...
Article
Full-text available
1.Rapid growth of the world's human population has increased pressure on landscapes to deliver high levels of multiple ecosystem services, including food and fibre production, carbon storage, biodiversity conservation and recreation. However, we currently lack general principles describing how to achieve this landscape multifunctionality. 2.We comb...
Article
Full-text available
In tropical montane cloud forests, climate change can cause upslope shifts in the distribution ranges of species, leading to reductions in distributional range. Endemic species with small ranges are particularly vulnerable to such decreases in range size, as the population size may be reduced significantly. To ensure the survival of cloud forest sp...
Data
Relationship between temperature anomalies and extrapolated mean altitude of El Oro parakeets for the years 1985, 1986, 2002, 2011, and 2012. A temperature increase of 1°C resulted in an increase in altitude of 416 m (depicted by the blue line). (TIF)
Data
List of models used in the IPCC WG1 AR5 Annex I: Atlas of global and regional climate projections (Stocker et al., 2013). (DOCX)
Article
Tropical cloud forests are under severe distress, as deforestation leads to forest fragmentation and degradation. This represents a severe threat to small-ranged, forest-dependent species, as they are at risk of losing habitat and connectivity between populations. These detrimental effects are aggravated by upslope range shifts caused by climate ch...
Article
Full-text available
Mutualistic interactions between plants and animals can affect both plant and animal communities, and potentially leave imprints on plant demography. Yet, no study has simultaneously tested how trait variation in plant resources shapes the diversity of animal consumers, and how these interactions influence seedling recruitment. Here, we analyzed wh...
Article
The Chocó-Tumbesian region of western Ecuador is one of the 25 global biodiversity hotspots harbouring high numbers of endemic species, which are heavily threatened by habitat loss and fragmentation. Moreover, ongoing climate change in the tropics drives species uphill as lower-lying areas are becoming constantly drier. Such upslope movement can po...
Article
Fleshy-fruited plants rely on animal frugivores to disperse their seeds, and seed removal by frugivores may leave an imprint on seedling recruitment. However, to what extent plant–frugivore interactions are related to seedling recruitment has rarely been quantified at the community level, especially in species-rich tropical forests. In this study,...
Article
Full-text available
Density-dependent processes are fundamental mechanisms for the regulation of populations. Ecological theories differ in their predictions on whether increasing population density leads to individual adjustments of survival and reproductive output or to dominance and monopolization of resources. Here, we use a natural experiment to examine which fac...
Article
Full-text available
Tropical montane ecosystems are biodiversity hotspots harbouring many endemics that are confined to specific habitat types within narrow altitudinal ranges. While deforestation put these ecosystems under threat, we still lack knowledge about how heterogeneous environments like the montane tropics promote population connectivity and persistence. We...
Data
Prior and hyperprior parameters for runs conducted with MSVAR 1.3. (DOCX)
Data
Genetic structure within the three study sites as inferred from the Geneland analysis. (DOCX)
Data
Pairwise genetic differentiation measured as Jost´s D and GST for n = 65 individuals. (DOCX)
Data
Mean log-likelihood LnP(K) (filled circles) and mean delta K (open circles) based on 15 replicates for each number of K clusters. (DOCX)
Data
Genotype table. Given are genotypes of each individual and sample location. (XLSX)
Article
Full-text available
Throughout the tropics, pristine forests disappear at an alarming pace. This presents a severe threat to forest-dependent species. Especially dispersal-limited understory birds are affected by forest loss. We here explored the effects of habitat fragmentation on the genetic structure and the morphology of the Ecuadorian Tapaculo (Scytalopus robbins...
Article
Recent studies have shown that the diversity of flowering plants can enhance pollinator richness and visitation frequency and thereby increase the resilience of pollination. It is assumed that flower traits explain these effects, but it is still unclear which flower traits are responsible, and knowing that, if pollinator richness and visitation fre...
Article
Pollinators and seed dispersers depend on flower and fruit colors as signals to mediate their interactions with plants. Signaling theory makes the general prediction that conspicuous signals will be selected because they increase detectability. However, direct evidence that conspicuous flower and fruit colors affect the fitness of plants in natural...
Article
The traits of animals and plants influence their interaction networks, but the significance of species' traits for the resulting ecosystem functions is poorly understood. A crucial ecosystem function in the tropics is seed dispersal by animals. While the importance of species' traits for structuring plant-frugivore networks is supported by a number...
Article
Full-text available
Many experiments have shown that loss of biodiversity reduces the capacity of ecosystems to provide the multiple services on which humans depend. However, experiments necessarily simplify the complexity of natural ecosystems and will normally control for other important drivers of ecosystem functioning, such as the environment or land use. In addit...
Article
Colour change in flowers (with age and/or after pollination) is taxonomically widespread, has evolved repeatedly, and has a range of putative selective benefits linked to modifying pollinator behaviour; however, this phenomenon seems paradoxically uncommon. We explore this paradox by reviewing the empirical evidence and argue that the evolution and...
Article
Leaf shape, size, and colour are used by herbivores to identify sources of palatable foliage for food. It is possible, therefore, that an undefended plant might gain protection from herbivores by matching leaf characteristics of a chemically defended species. We demonstrate the use of a geometric morphometric approach to quantify spatial variation...
Article
Habitat characteristics determine the presence of individuals through resource availability, but at the same time, such features also influence the occurrence of parasites. We analyzed how birds respond to changes in interior forest structures, to forest management regimes, and to the risk of haemosporidian infections. We captured and took blood sa...
Article
Full-text available
Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity-multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abund...
Article
Full-text available
Habitat characteristics determine the presence of individuals through resource availability, but at the same time, such features also influence the occurrence of parasites. We analyzed how birds respond to changes in interior forest structures, to forest management regimes, and to the risk of haemosporidian infections. We captured and took blood sa...
Article
Full-text available
Aims Nectar is one of the most common floral rewards offered to pollinators by plants. Depending on the plant species, nectar is offered openly or in tubes of various lengths restricting accessibility of this resource for flower visitors with short mouthparts. If attracting pollinators that match floral morphology increases pollination efficiency,...
Article
Full-text available
In cooperatively breeding species, in which non-breeding helpers assist in rearing the offspring of breeding individuals, conflicts of interest commonly occur between breeders and helpers over their respective contributions to offspring care. During such conflicts, breeders might use aggressive behavior to enforce contributions of helpers to offspr...
Article
Signals and cues are extensively used in social interactions across diverse communication systems. Here we extend an existing theoretical framework to explore investment by emitters and perceivers in the fidelity with which cues and signals associated with the former are detected by the latter. Traits of the emitter that improve cue or signal fidel...
Article
Full-text available
Species' functional roles in key ecosystem processes such as predation, pollination or seed dispersal are determined by the resource use of consumer species. An interaction between resource and consumer species usually requires trait matching (e.g. a congruence in the morphologies of interaction partners). Species' morphology should therefore deter...
Article
Full-text available
Avian research has begun to reveal associations between candidate genes and migratory behaviors of captive birds, yet few studies utilize genotypic, morphometric, and phenological data from wild individuals. Previous studies have identified an association between ADCYAP1 polymorphism and autumn migratory behavior (restlessness, or zugunruhe), but l...
Data
ADCYAP1 allele frequency histograms (allele size in base pairs) per population. Population codes: Ub = Uebersyren, LU; Fr = Freiburg, DE; Rz = Radolfzell, DE; Os = Oslo, NO; Kf = Kefermarkt, AT; Vn = Vienna, AT; Ry = Rybachy, RU; Bw = Białowieża Forest, PL; Km = Kalimok, BG. Geographic coordinates for collecting localities can be found in S1 Table....
Data
ADCYAP1 Allele frequencies by population (sample size) and mean allele frequencies across all populations. (DOC)
Data
Generalized linear model fit estimates for all 9 populations, Set 1. Effects on standardized dayscore are categorized as: Effect of wing shape: measures wing length (log(Wing L)) and wing pointedness (wing P); Effect of genetic variation measures: size of shorter ADCYAP1 allele (AD1), size of longer ADCYAP1 allele (AD2), mean ADCYAP1 allele size (m...
Data
Generalized linear model fit estimates for 6 morphometrically standardized populations. See S3 Table for details. (DOC)
Data
Female effect of wing shape (pointed vs. round) x heterozygosity (homozygote vs. heterozygote) on spring arrival (dayscore). P = pointed wing tips (blue, Wing P > 0.5346), 1st quartile of Holynski Index distribution; R = round wing tips (green, Wing P < 0.4431), 4th quartile of Holynksi Index distribution; Hom = homozygote and Het = heterozygote at...
Data
Generalized linear model fit estimates for all 9 populations, Set 4. See S3 Table for details. (DOC)
Data
Density plots of Freiburg dayscores for males (A) and females (B) from 2007–2011. (TIF)
Data
Mean statistics for blackcap populations. A) all blackcaps; B) male blackcaps; C) female blackcaps. Population codes coincide with Fig 1 and S1 Fig. Geographic location of each sampling population in decimal degrees (lat °E/long °N); Total sample size (N total); mean wing length (wing L); mean wing pointedness determined with Holynski Index (wing P...
Data
Generalized linear model fit estimates for all 9 populations, Set 2. See S3 Table for details. (DOC)
Data
Generalized linear model fit estimates for all 9 populations, Set 3. See S3 Table for details. (DOC)
Article
Full-text available
A novel migratory polymorphism evolved within the last 60 years in blackcaps (Sylvia atricapilla) breeding sympatrically in southwestern Germany. While most individuals winter in the traditional areas in the Mediterranean, a growing number of blackcaps started migrating to Britain instead. The rapid microevolution of this new strategy has been attr...
Data
Number of birds used for the different analyses, with their respective sexes and wintering grounds. (DOCX)
Article
Full-text available
Communication is ubiquitous. Developing a framework for the diversity of signals has important consequences for understanding alternative models of sexual selection and the processes contributing to speciation. In this article we review how models of neutral evolution in the perceptual space of signal perceivers provide a first step toward construc...
Article
Full-text available
The recognition that animals sense the world in a different way than we do has unlocked important lines of research in ecology and evolutionary biology. In practice, the subjective study of natural stimuli has been permitted by perceptual spaces, which are graphical models of how stimuli are perceived by a given animal. Because colour vision is arg...
Article
Whether plants use leaf colour to deter herbivores remains controversial. The warning signal hypothesis predicts that red pigmentation is adaptive by reducing herbivory; plants with predominantly red foliage should have higher fitness than those with green leaves. Despite many discussions, this prediction has rarely been tested, and alternative, no...
Article
PREMISE OF THE STUDY: Most bird-dispersed fruits are green when unripe and become colored and conspicuous when ripe, signaling that fruits are ready to be consumed and dispersed. The color pattern for fruits of Miconia albicans (Melastomataceae), however, is the opposite, with reddish unripe and green ripe fruits. We (1) verified the maintenance ov...
Article
Full-text available
Mutualisms can be seen as biological markets in which participating species exchange resources and services. Advertisements like the colors fleshy fruits are commonly used to attract mutualistic partners such seed dispersers. Although advertisements are common, the strategies employed in partner attraction and shaping the diversity of advertisement...
Data
Full-text available
Brycon amazonicus is an important freshwater migratory fish in the Amazon Basin. 29 Studies involving populations of B. amazonicus are of great importance for the conservation and 30 management of this species. We developed eight microsatellite loci and applied them to 31 investigate the genetic variation of 32 wild individuals from Catalan lake of...
Article
Full-text available
Flower colours are important cues shaping the interaction between plants and pollinators. Plants flowering in distinct habitats like grasslands and forests present their flowers in very different light environments and against different backgrounds. Since most Angiosperms depend on or profit from pollination by animals, plants may exhibit flower co...
Article
Full-text available
Global change, especially land-use intensification, affects human well-being by impacting the delivery of multiple ecosystem services (multifunctionality). However, whether biodiversity loss is a major component of global change effects on multifunctionality in real-world ecosystems, as in experimental ones, remains unclear. Therefore, we assessed...
Article
Many endangered species suffer from the loss of genetic diversity, but some populations may be able to thrive even if genetically depleted. In order to investigate the underlying genetic processes of population bottlenecks we apply an innovative approach for assessing genetic diversity in the last known population of the endangered Pale-headed Brus...
Article
Full-text available
Urban forests as hubs for novel zoonosis: blood meal analysis, seasonal variation in Culicoides (Diptera: Ceratopogonidae) vectors, and avian haemosporidians – CORRIGENDUM - Volume 141 Issue 10 - DIEGO SANTIAGO-ALARCON, PETER HAVELKA, EDUARDO PINEDA, GERNOT SEGELBACHER, H. MARTIN SCHAEFER
Article
Plant strategies frequently vary from opportunistic pollination to specialization to single pollinators within the same community. Unraveling the proximate mechanisms that determine the degree of plant generalization to pollinators has become a primary goal of pollination ecology. Color signaling is a potentially important mechanism because it is w...
Article
Full-text available
Using 454 pyro-sequencing, we established a microsatellite dataset of 12 polymorphic markers for the endangered Pale-headed Brushfinch (Atlapetes pallidiceps). Within 24 individuals, mean number of alleles ranged from 2 to 13, observed heterozygosity from 0.17 to 1.0, expected heterozygosity from 0.16 to 0.91, and polymorphic information content fr...
Article
The handicap principle has been the overarching framework to explain the evolution and maintenance of communication. Yet, it is becoming apparent that strategic costs of signalling are not the only mechanism maintaining signal honesty. Rather, the fidelity of detecting signals can itself be strongly selected. Specifically, we argue that the fidelit...
Article
Functional relationships between species groups on macroecological scales have often been inferred from comparisons of species numbers across space. On large spatial scales, however, it is difficult to assess whether correlations of species numbers represent actual functional relationships. Here, we investigated the functional relationship between...
Article
Was beeinflusst die Effektivität von visuellen Signalen, so dass sie eine Antwort von Empfängern auslösen? Experimentelle und theoretische Arbeiten in so unterschiedlichen Feldern wie sexueller Selektion und Pflanze-Tier Interaktionen haben eine Selektion auf höhere Auffälligkeit von Signalen nachgewiesen. Um die Auffälligkeit von Signalen bestimme...
Article
Full-text available
A long-standing but controversial hypothesis assumes that carnivorous plants employ aggressive mimicry to increase their prey capture success. A possible mechanism is that pitcher plants use aggressive mimicry to deceive prey about the location of the pitcher's exit. Specifically, species from unrelated families sport fenestration, i.e. transparent...
Article
Full-text available
Consuming food rich in antioxidants may help organisms to increase their antioxidant defences and avoid oxidative damage. Under the hypothesis that organisms actively consume food for its antioxidant properties, they would need to do so in view of other physiological requirements, such as energy requirements. Here, we observed that Gouldian finches...
Article
Full-text available
Although it is known that parents can differ in their optimal resource allocation to offspring in size-structured broods, the mechanisms determining differences in allocation rules of carers are not yet clarified. In cooperatively breeding species, breeders and non-reproductive helpers often differ in their fitness payoffs of providing care and in...
Article
Full-text available
We present a formal model of Janzen's influential theory that competition for resources between microbes and vertebrates causes microbes to be selected to make these resources unpalatable to vertebrates. That is, fruit rots, seeds mould and meat spoils, in part, because microbes gain a selective advantage if they can alter the properties of these r...
Article
Full-text available
Communication is a characteristic of life, but its reliability and basic definition are hotly debated. Theory predicts that trade among mutualists requires high reliability. Here, we show that moderate reliability already allows mutualists to optimize their rewards. The colours of Mediterranean fleshy-fruits indicate lipid rewards (but not other nu...
Article
Full-text available
The concept of biological markets aims to explain how organisms interact with each other. Market theory predicts that organisms choose the most rewarding partner in mutualisms. However, partner choice may also be influenced by advertisement which may not be reliable. In seed dispersal mutualism, we analysed whether seed dispersers prioritise taste...
Article
Full-text available
Communication in plant–animal mutualisms frequently involves multiple perceivers. A fundamental uncertainty is whether and how species adapt to communicate with groups of mutualists having distinct sensory abilities. � We quantified the colour conspicuousness of flowers and fruits originating from one Euro- pean and two South American plant communi...
Article
Full-text available
Thermal stress leads to increased production of reactive oxygen species. If an organism is not able to simultaneously mount an efficient antioxidant defense system, this may lead to increased oxidative damage, which is potentially deleterious in terms of health and fitness. Exposure to cold or heat is therefore expected to be associated with a high...
Article
Full-text available
Human-induced forest modification can alter parasite-host interactions and might change the persistence of host populations. We captured individuals of two widespread European passerines (Fringilla coelebs and Sylvia atricapilla) in southwestern Germany to disentangle the associations of forest types and parasitism by haemosporidian parasites on th...
Article
Human-induced forest modification can alter parasite-host interactions and might change the persistence of host populations. We captured individuals of two widespread European passerines (Fringilla coelebs and Sylvia atricapilla) in southwestern Germany to disentangle the associations of forest types and parasitism by haemosporidian parasites on th...