Differential Dispersal Abilities Research Articles

Phylogeography of a ‘great speciator’ (Aves:Edolisoma tenuirostre) reveals complex dispersal and diversification dynamics across the Indo‐Pacific

AbstractAimWe derive a new phylogenetic framework of the Indo‐Pacific avian genusEdolisomabased on a dense taxon sampling and use it in an explicit spatiotemporal framework to understand the history of intraspecific diversification dynamics in a ‘great speciator’, the CicadabirdEdolisoma tenuirostre/remotumcomplex.LocationThe Indo‐Pacific island region, Australia and New Guinea.TaxonCorvoid passerine birds (Passeriformes).MethodsWe used Bayesian phylogenetic methods (beast) to construct a time‐calibrated molecular phylogeny of all 19 species in the genusEdolisomaand 27 of 29 subspecies of theE. tenuirostre/remotumcomplex (previouslyCoracina tenuirostris) primarily based on one mitochondrial DNA marker. Ancestral area reconstruction methods (‘BioGeoBEARS’) were used to infer the historical biogeography of the genus. We used population‐level analyses to assess intraspecific phylogeography and a molecular species delimitation test to evaluate the current taxonomy. A morphometric dataset was used to discuss differential dispersal ability among taxa.ResultsEdolisomaoriginated in the late Miocene and diversification within theE. tenuirostre/remotumcomplex began in the Pleistocene. Within the North Melanesian and North Wallacean archipelagos, which have experienced several waves of diversification, we find significant patterns of genetic isolation by distance, but not within the Australo‐Papuan ‘mainland’, which was recently back‐colonized from these archipelagos. Based on the phylogeny, we suggest several taxonomic changes. We also discuss evidence of taxon cycles withinEdolisomabased on correlations of species age, elevational ranges and dispersal ability.Main conclusionsThe biogeographical history and patterns of differentiation between phylogroups withinE. tenuirostresupport the importance of barriers to gene flow in island systems. Examples of both recent genetic exchange across significant sea barriers and differentiation across much smaller water gaps suggest complex dispersal and diversification dynamics. The capacity for dispersal away from islands, and gradual shifts in dispersal ability in relation to the geographical setting, is supported as important factors in generating a ‘great speciator’.

A little bit everyday: range size determinants inArachis(Fabaceae), a dispersal‐limited group

AbstractAimEven though all species ofArachis(wild peanuts) develop pods underground (geocarpy), strongly limiting their dispersal ability, this genus is quite widespread in South America. Thus, our goal was to test potential explanations for howArachisspecies may have achieved their current distribution.LocationSouth America.MethodsWe used a dated phylogeny and 1,052 georeferenced records to run several analyses to select the variables that best explain the variation in range size inArachisspecies. We tested a set of models incorporating both abiotic (age, association with rivers, niche parameters) and biotic (life span, vegetative growth, dispersal ability) factors thought to influence geographical distribution in order to select those variables that may best explain the range size ofArachisspecies.ResultsWe found that no single factor was able to satisfactorily explain the geographical distribution of wild peanuts. Our results showed thatArachisrange sizes are influenced by a combination of differential dispersal ability and age, although the effect of time alone was small. We also found that asArachisspecies are geocarpic, their dispersal ability is positively influenced by presence of rhizomes, which improves the distances reached by individuals.Main conclusionsOur research shows that the range sizes of wild peanuts are mainly constrained by differential dispersal ability and time, and they are improved by the presence of rhizomatous growth. We also advocate that applying a set of candidate hypotheses to explain species range sizes is a much better alternative than previous attempts, in which single or few hypotheses have been tested at a time.

Comparative phylogeography of codistributed aquatic insects in western North America: insights into dispersal and regional patterns of genetic structure

Summary Phylogeographic studies provide insights about complex systems at different evolutionary scales. In addition to providing evidence about ecological processes at the organismal level, a synthesis of studies across taxa can illuminate broad phylogeographic patterns at the landscape scale. We compared the phylogeographic patterns of two codistributed species of aquatic insects, Pteronarcella badia (Plecoptera: Pteronarcyidae) and Drunella grandis (Ephemeroptera: Ephemerellidae), across much of their range in western North America. We conducted population genetic analyses of P. badia and D. grandis individuals that co‐occurred in 22 western North American localities. Patterns of genetic structure and gene flow were compared to test for differential dispersal ability and to determine whether broad‐scale phylogeographic trends are consistent with patterns seen in terrestrial taxa across a similar geographic area. We also evaluated whether patterns observed in these species fit previously proposed models of genetic structure in aquatic organisms. Pteronarcella badia showed greater genetic structure and lower rates of dispersal than D. grandis. Both taxa showed several shared geographic regions of genetic isolation, including the Bitterroot Valley in Montana, the Pacific Northwest, the southern Rocky Mountains and the Colorado Plateau. These broad‐scale phylogeographic patterns are largely consistent with trends observed in several terrestrial taxa across the sample area. D. grandis showed patterns of gene flow consistent with an isolation‐by‐distance model of genetic structure. Patterns observed in P. badia reflect elements of multiple models and may highlight the value of the dendritic network approach to understanding genetic patterns of aquatic taxa at broad geographic scales.

Mitochondrial genetic diversity, phylogeny and population structure of Hydropotes inermis in South Korea.

The water deer (Hydropotes inermis) is one of the rarest species of deer in the family Cervidae. Only two subspecies exist in East Asia, and few studies have examined the genetic characteristics of the species. Here, we investigated the genetic diversity, phylogeny and population differentiation of the Korean subspecies (H. inermis argyropus). Seventeen mitochondrial D-loop haplotypes (822 bp) were detected and analyzed from 107 individual samples, together with a Chinese subspecies (H. inermis inermis) haplotype. The genetic diversity of the Korean subspecies is lower (π = 0.756%, h = 0.867) than that of the Chinese subspecies estimated in a previous study. This low genetic diversity may result from historical anthropogenic disturbances and/or a founder effect during the glacial period. The phylogenetic tree and median-joining network showed no location-specific distribution of D-loop haplotypes, but revealed two major lineages, A and B, of water deer. The A and B lineages were separated from each other at the beginning of the Pleistocene era (2.1-1.3 million years ago), with a genetic divergence of 1.332 ± 0.340%. The genetic divergence within lineages A and B was 0.525 ± 0.167% and 0.264 ± 0.113%, respectively. This suggests that climate change affected the division of the two lineages. Water deer sampled from the three Korean regions (26 locations) were slightly distinct in their genetic structure (AMOVA: F(ST) = 0.28416, P < 0.00001; Φ(ST) = 0.19239, P < 0.00001). Such slight population differentiation may be derived from differential dispersal ability in males and females. The use of genetic markers, such as nuclear microsatellite and Y-linked DNA markers, and samples collected from various localities in East Asia should improve our understanding of the water deer's genetic characteristics.

Geographical patterns and partition of turnover and richness components of beta-diversity in faunas from Tocantins river valley

There has been a resurging interest in patterns of β-diversity, especially by the mechanisms driving broad-scale, continental and global patterns, and how partitioning β-diversity into richness (or nestedness) and turnover components can be linked with such mechanisms. Here we compared two recent methodologies to find richness and turnover components of β-diversity, using a large regional scale dataset of mammal, bird, reptiles and amphibian species found in seven regions of Central, North and Northeastern Brazil. As well as a simple comparison of the metrics available, we analyzed spatial patterns (i.e., distance-decay similarity) and the effects of biome type in these components using raw and partial Mantel tests. Our analyses revealed that turnover estimated using Baselga's (2010) approach is slightly higher than the estimate using Carvalho's et al. (2012) approach, but all analyses show consistent spatial patterns in species turnover using both methods. Spatial patterns in β-diversity revealed by Mantel tests are also consistent with expectations based on differential dispersal abilities. Our results also reinforce that spatial patterns in β-diversity, mainly in the turnover components expressing faunal differentiation, are determined by a mix or broad scale environmental effects and short distance spatially-structured dispersal.

Future Distribution of Arctic Char Salvelinus alpinus in Sweden under Climate Change: Effects of Temperature, Lake Size and Species Interactions

Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961-1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95% of 467 Swedish lakes. We predicted that Arctic char will lose 73% of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.

Symposium summary: Climate change biogeography

ISSN 1948‐6596 news and update Graham, C.H., Parra, J.L., Rahbek, C. & Mcguire, J.A. (2009). Phylogenetic structure in tropical hum‐ mingbird communities. Proceedings of the Na‐ tional Academy of Sciences, 106, 19673‐19678. Hoorn, C., Wesselingh, F.P., Ter Steege, H., Bermudez, M.A., Mora, A., Sevink, J., Sanmartin, I., Sanchez‐ Meseguer, A., Anderson, C.L., Figueiredo, J.P., Jaramillo, C., Riff, D., Negri, F.R., Hooghiemstra, H., Lundberg, J., Stadler, T., Sarkinen, T. & An‐ tonelli, A. (2010). Amazonia through time: An‐ dean uplift, climate change, landscape evolu‐ tion, and biodiversity. Science, 330, 927‐931. Sizling, A.L., Storch, D. & Keil, P. (2009). Rapoport's rule, species tolerances, and the latitudinal di‐ versity gradient: Geometric considerations. Ecol‐ ogy, 90, 3575‐3586. Stevens, G.C. (1989). The latitudinal gradient in geo‐ graphic range: How so many species coexist in the tropics. American Naturalist, 133, 240‐256. Webb, C.O., Ackerly, D.D., Mcpeek, M.A. & Donoghue, M.J. (2002). Phylogenies and community ecol‐ ogy. Annual Review of Ecology and Systematics, Edited by Matthew J. Heard symposium summary Climate change biogeography A contributed session at the 5th International Biogeography Society Conference – Heraklion, Greece, 7–11 January 2011 Anthropogenic climate change and its realized and potential impacts on biodiversity represent the kind of large‐scale complex phenomena for which the integrative broad‐scale view of biogeography is especially useful. This was well exemplified at the 5 th IBS conference’s contributed papers ses‐ sion on “climate change biogeography”. Earth’s climate has exhibited marked changes and fluc‐ tuations in the past, and several studies (B. Sandel et al., Aarhus University; G. Rodriguez‐Castaneda et al., Umea University) provided deep‐time per‐ spectives on climate‐change impacts on biodiver‐ sity, showing that the location and extent of long‐ term climatically stable areas have left strong im‐ prints in current large‐scale species diversity pat‐ terns. An important implication of these studies is that much species diversity may depend on cli‐ matic stability. Linked to this several studies ad‐ dressed the complexity of ecological responses to current and expected climate change, showing that tree‐lines may recede despite a warming cli‐ mate, due to the interacting effects of fire and dispersal limitation (C.D. Brown and J.F. Johns‐ tone, University of Saskatchewan), and that differ‐ ent ecological groups of closely related species may exhibit deviating responses to climate change, e.g. due to differential dispersal abilities and contingent differential lags in their responses to climate change (C. Hof et al., University of Co‐ penhagen). Finally, several studies highlighted the potentially critical losses due to 21 st century cli‐ mate change of not just species diversity, but also of unique evolutionary lineages within species (E. Vazquez‐Dominguez et al., Universidad Autonoma de Mexico). Even more worrying is the risk of wholesale loss of biodiversity from Amazonia, one of Earth’s most biodiverse regions (K.J. Feeley et al., Florida International University). Together the studies presented not only illustrate how progress in our understanding of climate‐change impacts on biodiversity is being provided by biogeographi‐ cal research, but also illustrate how the field is rapidly advancing by creative development and application of sophisticated modeling approaches that integrate ecology, physical geography, and genetics. Jens‐Christian Svenning Ecoinformatics & Biodiversity Group, Aarhus University, Denmark. e‐mail: svenning@biology.au.dk Edited by Dan Gavin © 2011 the authors; journal compilation © 2011 The International Biogeography Society — frontiers of biogeography 3.1, 2011

Metacommunity Dynamics: Decline of Functional Relationship along a Habitat Fragmentation Gradient

BackgroundThe metacommunity framework is crucial to the study of functional relations along environmental gradients. Changes in resource grain associated with increasing habitat fragmentation should generate uncoupled responses of interacting species with contrasted dispersal abilities.Methodology/Principal FindingsHere we tested whether the intensity of parasitism was modified by increasing habitat fragmentation in the well know predator-prey system linking the parasitoid Cotesia glomerata (Hymenoptera: Braconidae) to its main host Pieris brassicae (Lepidoptera: Pieridae). We collected information on herbivorous abundance and parasitism rate along an urbanization gradient from the periphery to the centre of Paris. We showed that butterfly densities were not influenced by habitat fragmentation, whereas parasitism rate sharply decreased along this gradient.Conclusions/SignificanceOur results provide novel insights into the mechanisms underlying the persistence of species in highly fragmented areas. They suggest that differential dispersal abilities could alter functional relationships between prey and predator, notably by a lack of natural predators.

Nested patterns of community assembly in the colonisation of artificial canopy habitats by oribatid mites

An observed species–area relationship (SAR) in assemblages of oribatid mites inhabiting natural canopy habitats (suspended soils) led to an experimental investigation of how patch size, height in canopy and moisture influence the species richness, abundance and community composition of arboreal oribatid mites. Colonisation by oribatid mites on 90 artificial canopy habitats (ACHs) of three sizes placed at each of three heights on the trunks of ten western redcedar trees was recorded over a 1‐year period. Fifty‐nine oribatid mite species colonised the ACHs, and richness increased with the moisture content and size of the habitat patch. Oribatid mite species richness and abundance, and ACH moisture content decreased with increasing ACH height in the canopy. Patterns in the species richness and community composition of ACHs were non‐random and demonstrated a significant nested pattern. Correlations of patch size, canopy height and moisture content with community nestedness suggest that species‐specific environmental tolerances combined with the differential dispersal abilities of species contributed to the non‐random patterns of composition in these habitats. In line with the prediction that niche‐selection filters out species from the regional pool that cannot tolerate environmental harshness, moisture‐stressed ACHs in the high canopy had lower community variability than ACHs in the lower canopy. Colonising source pools to ACHs were almost exclusively naturally‐occurring canopy sources, but low levels of colonisation from the forest floor were apparent at low heights within the ACH system. We conclude that stochastic dispersal dynamics within the canopy are crucial to understanding oribatid mite community structure in suspended soils, but that the relative importance of stochastic dispersal assembly may be dependent on a strong deterministic element to the environmental tolerances of individual species which drives non‐random patterns of community assembly.

INTER-YEAR CARRYOVER EFFECTS OF A NUTRIENT PULSE ON SPARTINA PLANTS, HERBIVORES, AND NATURAL ENEMIES

Pulsed resources, such as natural and anthropogenic inputs of nutrients into natural communities, can have important consequences for primary productivity, as well as for consumers and their predators. Little, however, is known of how a resource pulse influences community assemblages for periods longer than one growing season. This study, repeated twice and in two different habitats on a mid-Atlantic Spartina alterniflora salt marsh, showed that a one-time nitrogen (N) subsidy can have not only significant within- year effects on plant primary production and herbivore and natural enemy abundance, but can also have long-term effects on plants and arthropod food web structure. Spartina plants exhibited significantly greater biomass for 2-3 yr and elevated per- centage of N for up to two years following the nutrient pulse, an effect that had direct positive effects on herbivores that were sensitive to variation in plant N content. Populations of Prokelisia planthoppers (Hemiptera: Delphacidae) were elevated in fertilized plots for up to three years following the nutrient addition. However, Trigonotylus uhleri, an herbiv- orous mirid (Hemiptera: Miridae), was more abundant on previously fertilized plants only for a brief time, either within the same season as the nutrient addition, or for only one year after the pulse. The carryover effect of the nutrient pulse on plants and herbivores also propagated to the third trophic level. Both non-lycosid spiders (mostly linyphiids) and a specialist egg predator of Spartina planthoppers (Tytthus vagus) were more abundant in previously fertilized plots for up to two years following the nutrient pulse. In contrast, wolf spider (Lycosidae) densities were elevated in fertilized plots only within the same season as the initial fertilization pulse. Food web structure, as indexed by herbivore:predator ratio, was altered in plots that received a one-time N subsidy, with the arthropod food web in fertilized Spartina taking three years to resemble that of unperturbed Spartina. The response of particular herbivores and predators to the nutrient pulse was in part habitat dependent (contiguous Spartina meadows vs. isolated islets), suggesting that habitat heterogeneity combined with the differential dispersal ability of arthropods can influence the long-term response of a food web to a nutrient pulse.

Nestedness of north-west European land snail ranges as a consequence of differential immigration from Pleistocene glacial refuges.

We investigated whether ranges in continental biota are nested. We propose a test for nested subset structure which can detect nestedness even if there are several sets of nested subsets as expected on a larger geographical scale. The test is based on a Monte Carlo simulation with a null model that considers spatial autocorrelation of the occurrences of a taxon. The number of cases in which the occurrences of a species form a subset of the occurrences of another species is used as test statistic. In a case study we show that the ranges of north-west European land snail species are significantly nested. The geographic centres of the sets of nested subsets correlate with glacial refuges. The differential immigration of taxa restricted to southern refuges during the glacials was probably an important mechanism resulting in the observed nestedness of the ranges of the north-west European land snail species. Some species which were more widespread during Pleistocene glacials contribute little to the nested subset pattern and are not nested among themselves. A comparison between groups of species differing in their dispersal abilities indicates that differences in the degree of nestedness are primarily due to differences in the variance of range sizes and not in dispersal abilities. We found a very weak correlation between dispersal ability and the rank of ranges in the sets of nested subsets indicating that nestedness might in part be caused by differential dispersal abilities. We assume that the graded variation of environmental parameters might be more important in generating the nestedness of ranges of north-west European land snail species than their differential dispersal abilities.

History and taxonomy: their roles in the core-satellite hypothesis.

Metapopulation models are important in explaining the distribution and abundance of species through time and space. These models combine population dynamics with stochastic variation in extinction and immigration parameters associated with local populations. One of the predictions of metapopulation models is a bimodal distribution of species frequency of occurrence, a pattern that led to the development of the core-satellite species hypothesis. The spatial scale and taxonomic classification of past core-satellite studies has often been undefined. In our study, we have integrated metapopulation dynamics with the roles that differential dispersal ability and history play in the shaping of communities. The differences in distribution patterns between landbridge islands and oceanic islands, and among various taxa (birds, mammals, herptiles, arthropods, fish, and plants) are analyzed. The majority of landbridge islands comprised locally and regionally abundant species (core species), whereas the majority of oceanic islands had a uniform distribution (or no end-peak in their distribution). The patterns of distribution among the taxonomic groups also showed differences. Birds (good dispersers) consistently showed bimodal- and core-distribution patterns. The bimodal prediction of species distribution is best exemplified in the landbridge islands and in birds, and least in oceanic islands and in organisms other than birds. These results illustrate the importance of testing models with various taxonomic groups and at different spatial scales and defining these scales before formally testing the predictions of the models.

Forest Fragments in East-central Illinois: Islands or Habitat Patches for Mammals?

We surveyed the nonvolant mammals in 10 forest fragments embedded in a matrix of row crop agriculture in east-central Illinois to assess the impact of forest fragmentation on mammalian diversity and distributions. A total of 19 species were recorded during our study, including 16 native species that occur naturally in forest habitat. We found a significant species-area relationship and a significantly nested subset structure. In particular, gray squirrels, chipmunks and flying squirrels were only encountered in the larger, more continuous sites suggesting a negative effect of habitat fragmentation. Seven species were ubiquitous and we believe that several others occur periodically at all study sites, indicating that most mammalian species currently present have not had their distributions altered by changes in the intervening habitat. Though an analogy to oceanic islands may apply for some species, we believe that most mammals treat forest remnants as habitat patches rather than islands, and that mechanisms such as habitat selection, constraints due to home range size and differential dispersal ability best explain the observed distributions of mammals.

Early succession on lahars spawned by Mount St. Helens

The effects of isolation on primary succession are poorly documented. I monitored vegetation recovery on two Mount St. Helens lahars (mud flows) with different degrees of isolation using contiguous plots. Seventeen years after the eruption, species richness was stable, but cover continued to increase. That isolation affects community structure was confirmed in several ways. The dominance hierarchies of the lahars differed sharply. Detrended correspondence analysis on Lahar I showed a trend related to distance from an adjacent woodland, whereas vegetation on Lahar II was relatively homogeneous. Spectra of growth forms and dispersal types also differed. Lahar I was dominated by species with modest dispersal ability, while Lahar II was dominated by species with better dispersal. Variation between plots should decline through time, a prediction confirmed on Lahar II. Lahar I remained heterogeneous despite having developed significantly higher cover. Here, the increasing distance from the forest has prevented plots from becoming more homogeneous. At this stage of early primary succession, neither lahar is converging towards the species composition of adjacent vegetation. This study shows that isolation and differential dispersal ability combine to determine initial vegetation structure. Stochastic effects resulting from dispersal limitations may resist the more deterministic effects of competition that could lead to floristic convergence.