Oikos
Although rarely examined, apparent competition, whereby exotic plants increase consumer pressure on native plants, could play a significant role in affecting native plant establishment in invaded habitats. Moreover, although terrestrial consumer communities often contain many consumer species, little is known about which consumers may generate apparent competition, and whether the strength or mechanism...
We studied patterns of species co‐occurrence in communities of ectoparasitic arthropods (ixodid ticks, mesostigmate mites and fleas) harboured by rodent hosts from South Africa (Rhabdomys pumilio), South America (Scapteromys aquaticus and Oxymycterus rufus) and west Siberia (Apodemus agrarius, Microtus gregalis, Microtus oeconomus and Myodes rutilus) using null models. We compared frequencies of co‐occurrences...
In the present study we explore how annual variation in climate (late wet‐season rainfall) affects population demography in a gape‐limited obligate piscivorous predator, the Arafura filesnake Acrochordus arafurae in the Australian tropics. These aquatic snakes display extreme sexual dimorphism, with body sizes and relative head sizes of females much larger than those of males. Two consecutive years...
We present a new methodology to estimate rates of energy acquisition, maintenance, reproductive investment and the onset of maturation (four‐trait estimation) by fitting an energy allocation model to individual growth trajectories. The accuracy and precision of the method is evaluated on simulated growth trajectories. In the deterministic case, all life history parameters are well estimated with negligible...
A topic under intensive study in community ecology and biogeography is the degree to which microscopic, as well as macroscopic organisms, show spatially‐structured variation in community characteristics. In general, unicellular microscopic organisms are regarded as ubiquitously distributed and, therefore, without a clear biogeographic signal. This view was summarized 75 years ago by Baas‐Becking,...
It has been proposed that some specific locations of bird's nests have higher intrinsic chances of being depredated than other locations. This predicts that fates of consecutive nesting attempts at the same site should be repeatable. We used 20 pairs of old thrush nests to simulate repeated nesting attempts at the same sites, both within and between breeding seasons (n=40 sites×2 trials×2 years=160)...
The niche is one of the most important concepts in ecology. However, there has been a persistent controversy on how to define, measure, and predict the ecological niche of an organism. Here I argue that these problems arise in part because the niche is defined by the set of all possible environments, many of which do not exist in nature. A complete description of the niche would require knowledge...
In food webs heavily influenced by multi‐annual population fluctuations of key herbivores, predator species may differ in their functional and numerical responses as well as their competitive ability. Focusing on red and arctic fox in tundra with cyclic populations of rodents as key prey, we develop a model to predict how population dynamics of a dominant and versatile predator (red fox) impacted...
The science behind ecology has been contested for years, partially because of the misuse and misrepresentation of concepts within ecology. This paper discusses the use of Bergmann's rule, a fundamental rule of biogeography. The rule was proposed by Carl Bergmann in 1847 and was published only in German; therefore, the majority of researchers have relied on a single translation by Mayr suggesting that...
A long‐standing problem in ecology is to understand how the species–abundance distribution (SAD) varies with sampling scale. The problem was first characterized by Preston as the veil line problem. Although theoretical and empirical studies have now shown the nonexistence of the veil line, this problem has generated much interest in scaling biodiversity patterns. However, research on scaling SAD has...
Seed dispersal is qualitatively effective when it increases recruitment probability. A poorly studied factor likely affecting recruitment is the spatial distribution of dispersed seeds. Seed‐caching animals are thought to disperse seeds in a way that reduces clumping and density to impede cache pilfering. Furthermore, dispersal might differ depending on whether the seed is immediately consumed versus...
The reproductive value hypothesis predicts that if residual reproductive value declines as a female ages, then young females should allocate less of available energy to current fecundity and more to future reproduction; whereas, older females should allocate more of available energy to current fecundity and less to future reproduction (i.e. survival). We test the prediction that older female Gambusia affinis...
What selection pressures drive the evolution of offspring size? Answering this fundamental question for any species requires an understanding of the relationship between offspring size and offspring fitness. A major goal of evolutionary ecologists has been to estimate this critical relationship, but for organisms with complex lifecycles, logistical constraints restrict most studies to early life‐history...
For the past 30 years evolutionary biologists have used a fictional tale about engineer and businessman Henry Ford to help illustrate the undesirability of over‐design. Thus, on discovering that kingpins were rarely damaged in scrapped Model T automobiles, Henry Ford is alleged to have concluded that the kingpins were unnecessarily durable and asked that they be built to a cheaper specification. The...
Research over the past decade has established spatial resource subsidies as important determinants of food web dynamics. However, most empirical studies have considered the role of subsidies only in terms of magnitude, ignoring an important property of subsidies that may affect their impact in recipient food webs: the trophic structure of the subsidy relative to in situ resources. This may be especially...
One possible response of species to climate change is shifting their geographical range so as to track their climatic niche. Many concerns have been raised about the species ability to disperse effectively. I argue that species may have mechanisms, like temperature‐dependent sex determination (TSD), that are responsive to climate change and may facilitate an appropriate shift in their geographical...
Many generalist populations may actually be composed of relatively specialist individuals. This ‘individual specialization’ may have important ecological and evolutionary implications. Although this phenomenon has been documented in more than one hundred taxa, it is still unclear how individuals within a population actually partition resources. Here we applied several methods based on network theory...
A key challenge in the study of mutualism is to understand the mechanisms that prevent cheating. In some systems, host retaliation against cheaters prevents the breakdown of cooperation. Here, we focus on the converse of this demonstration, and ask whether hosts that fail to retaliate are commonly inhabited by cheaters. We do so using the classic ant–plant interaction, in which plants provide ant‐housing...
Most insects harbour a community of parasitoids that coexist in spite of competition for resources. One potential mechanism for coexistence of competitors is a tradeoff between dispersiveness and local competitive ability. Here we present a study of competition between the specialized parasitoids Hyposoter horticola and Cotesia melitaearum sharing the Glanville fritillary butterfly, Melitaea cinxia...
Most recent studies describing pollination networks are based on observed flower visits, and few have explicitly tested if the floral visitors actually carry pollen. Since floral visitors can vary in their ability to remove and transfer pollen, it is important to show that visitation patterns reflect effective pollination. Given the difficulty of measuring per‐visit pollen deposition at the community...