Abstract. Illuminating the ecological and evolutionary dynamics of parasites is one of the most pressing issues facing modern science, and is critical for basic science, the global economy, and human health. Extremely important to this effort are data on the diseasecausing organisms of wild animal hosts (including viruses, bacteria, protozoa, helminths, arthropods, and fungi). Here we present an updated version of the Global Mammal Parasite Database, a database of the parasites of wild ungulates (artiodactyls and perissodactyls), carnivores, and primates, and make it available for download as complete flat files. The updated database has more than 24,000 entries in the main data file alone, representing data from over 2700 literature sources. We include data on sampling method and sample sizes when reported, as well as both "reported" and "corrected" (i.e., standardized) binomials for each host and parasite species. Also included are current higher taxonomies and data on transmission modes used by the majority of species of parasites in the database. In the associated metadata we describe the methods used to identify sources and extract data from the primary literature, how entries were checked for errors, methods used to georeference entries, and how host and parasite taxonomies were standardized across the database. We also provide definitions of the data fields in each of the four files that users can download.
The distribution of parasites across mammalian hosts is complex and represents a differential ability or opportunity to infect different host species. Here, we take a macroecological approach to investigate factors influencing why some parasites show a tendency to infect species widely distributed in the host phylogeny (phylogenetic generalism) while others infect only closely related hosts. Using a database on over 1400 parasite species that have been documented to infect up to 69 terrestrial mammal host species, we characterize the phylogenetic generalism of parasites using standard effect sizes for three metrics: mean pairwise phylogenetic distance (PD), maximum PD and phylogenetic aggregation. We identify a trend towards phylogenetic specialism, though statistically host relatedness is most often equivalent to that expected from a random sample of host species. Bacteria and arthropod parasites are typically the most generalist, viruses and helminths exhibit intermediate generalism, and protozoa are on average the most specialist. While viruses and helminths have similar mean pairwise PD on average, the viruses exhibit higher variation as a group. Close-contact transmission is the transmission mode most associated with specialism. Most parasites exhibiting phylogenetic aggregation (associating with discrete groups of species dispersed across the host phylogeny) are helminths and viruses.
Classic biogeographic studies emphasized differences in species composition between regions to define biogeographic provinces and delimit biogeographic boundaries. Here we analyze the permeability of biogeographic boundaries to different species to gain mechanistic insight into the processes that maintain species boundaries in the coastal ocean. We identify sites with high frequencies of range boundaries using almost 1800 benthic marine invertebrates along the northwestern Atlantic coast and address whether their magnitude and location vary as a function of species’ taxonomy, pelagic larval duration and depth distribution. We observed clusters of species boundaries at Cape Hatteras, Cape Cod and the Bay of Fundy that are largely independent of taxonomic group. However, the boundaries were permeable and asymmetric, with a higher percentage of species shared across boundaries in the equatorward direction (82%) than in the reverse direction (59%). This pattern was particularly strong for shallow species (median occurrence depth < 20 m). Pelagic larval duration was more important to explain distributions of boundaries for deep species (median occurrence depth > 20 m), where species with long larval dispersal had significantly higher occurrence of boundaries than species with short larval dispersal. When they do exist, species boundaries seem to be set by the interaction of currents, depth distribution and pelagic larval duration. Importantly, species boundaries tend to be pinned to regions of reduced water transport, which might explain why species boundaries are concentrated in narrow geographical areas.
The type of metric and weighting method used in meta‐analysis can create bias and alter coverage of confidence intervals when the estimated effect size and its weight are correlated. Here, we investigate bias associated with the common metric, Hedges’ d, under conditions common in ecological meta‐analyses. We simulated data from experiments, computed effect sizes and their variances, and performed meta‐analyses applying three weighting schemes (inverse variance, sample size, and unweighted) for varying levels of effect size, within‐study replication, number of studies in the meta‐analysis, and among‐study variance. Unweighted analyses, and those using weights based on sample size, were close to unbiased and yielded coverages close to the nominal level of 0.95. In contrast, the inverse‐variance weighting scheme led to bias and low coverage, especially for meta‐analyses based on studies with low replication. This bias arose because of a correlation between the estimated effect and its weight when using the inverse‐variance method. In many cases, the sample size weighting scheme was most efficient, and, when not, the differences in efficiency among the three methods were relatively minor. Thus, if using Hedges’ d, we recommend using weights based upon sample size that do not involve individual study estimates of the effect size.
The evolutionary pressures that drive long larval planktonic durations in some coastal marine organisms, while allowing direct development in others, have been vigorously debated. We introduce into the argument the asymmetric dispersal of larvae by coastal currents and find that the strength of the currents helps determine which dispersal strategies are evolutionarily stable. In a spatially and temporally uniform coastal ocean of finite extent, direct development is always evolutionarily stable. For passively drifting larvae, long planktonic durations are stable when the ratio of mean to fluctuating currents is small and the rate at which larvae increase in size in the plankton is greater than the mortality rate (both in units of per time). However, larval behavior that reduces downstream larval dispersal for a given time in plankton will be selected for, consistent with widespread observations of behaviors that reduce dispersal of marine larvae. Larvae with long planktonic durations are shown to be favored not for the additional dispersal they allow, but for the additional fecundity that larval feeding in the plankton enables. We analyzed the spatial distribution of larval life histories in a large database of coastal marine benthic invertebrates and documented a link between ocean circulation and the frequency of planktotrophy in the coastal ocean. The spatial variation in the frequency of species with planktotrophic larvae is largely consistent with our theory; increases in mean currents lead to a decrease in the fraction of species with planktotrophic larvae over a broad range of temperatures.
Understanding factors that facilitate interspecific pathogen transmission is a central issue for conservation, agriculture, and human health. Past work showed that host phylogenetic relatedness and geographical proximity can increase cross‐species transmission, but further work is needed to examine the importance of host traits, and species interactions such as predation, in determining the degree to which parasites are shared between hosts. Here we consider the factors that predict patterns of parasite sharing across a diverse assemblage of 116 wild ungulates (i.e., hoofed mammals in the Artiodactyla and Perissodactyla) and nearly 900 species of micro‐ and macroparasites, controlling for differences in total parasite richness and host sampling effort. We also consider the effects of trophic links on parasite sharing between ungulates and carnivores. We tested for the relative influence of range overlap, phylogenetic distance, body mass, and ecological dissimilarity (i.e., the distance separating species in a Euclidean distance matrix based on standardized traits) on parasite sharing. We also tested for the effects of variation in study effort as a potential source of bias in our data, and tested whether carnivores reported to feed on ungulates have more ungulate parasites than those that use other resources. As in other groups, geographical range overlap and phylogenetic similarity predicted greater parasite community similarity in ungulates. Ecological dissimilarity showed a weak negative relationship with parasite sharing. Counter to our expectations, differences, not similarity, in host body mass predicted greater parasite sharing between pairs of ungulate hosts. Pairs of well‐studied host species showed higher overlap than poorly studied species, although including sampling effort did not reduce the importance of biological traits in our models. Finally, carnivores that feed on ungulates harboured a greater richness of ungulate helminths. Overall, we show that the factors that predict parasite sharing in wild ungulates are similar to those known for other mammal groups, and demonstrate the importance of controlling for heterogeneity in host sampling effort in future analyses of parasite sharing. We also show that ecological interactions, in this case trophic links via predation, can allow sharing of some parasite species among distantly related host species.
ABSTRACT. From the beginning of the 19th century on, several small sampling trips as well as large national and international scientific expeditions have been carried out to Easter Island (EI) and Salas y Gómez Island (SGI). The objective of this study is to compile, synthesize and analyze published information about the biodiversity of macroalgae, macroinvertebrates and fishes associated with EI-SGI, updating the state of knowledge and making it available for the development of conservation plans. We searched all the available sources of information, such as scientific publications, scientific expeditions, fisheries data, technical reports, books, databases and online sources. We found 964 species reported within EI-SGI (143 species of macroalgae, 605 macroinvertebrates and 216 fishes), the majority for EI (923); for SGI 171 species have been reported. Species richness has increased over time, without leveling off, as sampling effort increases. However, seamounts and hydrothermal vents have been poorly studied in Chile´s Exclusive Economic Zone (EEZ). A high percentage of endemism has been determined for the majority of the taxonomic groups, with mollusks and poriferans exhibiting the highest levels of endemism (33-34%). Thus, the Rapanuian biogeographic province can be clearly identified, but information to differentiate between EI and SGI, and direct island-specific conservation efforts, is lacking. Nevertheless, the most vulnerable yet unprotected habitats (hydrothermal vents, higher diversity of seamounts size) are located towards the western limit of the EEZ.
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