Estimating seed dispersal distance: A comparison of methods using animal movement and plant genetic data on two primate‐dispersed Neotropical plant species

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Morphological variation associated with dispersal capacity in a tree‐killing bark beetle Dendroctonus ponderosae Hopkins

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Extrafloral nectar increases seed removal by ants in Turnera ulmifolia

To investigate whether extrafloral nectar (EFN) increases seed dispersal in Turnera ulmifolia, we measured seed removal on plants with and without EFN. Plants producing EFN had more seeds removed than control plants, suggesting that EFN does play a role in seed dispersal. This is a novel function of EFN.     

Animal behaviour shapes the ecological effects of ocean acidification and warming: moving from individual to community‐level responses

Biological communities are shaped by complex interactions between organisms and their environment as well as interactions with other species. Humans are rapidly changing the marine environment through increasing greenhouse gas emissions, resulting in ocean warming and acidification. The first response by animals to environmental change is predominantly through modification of their behaviour, which in turn affects species interactions and ecological processes. Yet, many climate change studies ignore animal behaviour. Furthermore, our current knowledge of how global change alters animal behaviour is mostly restricted to single species, life phases and stressors, leading to an incomplete view of how coinciding climate stressors can affect the ecological interactions that structure biological communities. Here, we first review studies on the effects of warming and acidification on the behaviour of marine animals. We demonstrate how pervasive the effects of global change are on a wide range of critical behaviours that determine the persistence of species and their success in ecological communities. We then evaluate several approaches to studying the ecological effects of warming and acidification, and identify knowledge gaps that need to be filled, to better understand how global change will affect marine populations and communities through altered animal behaviours. Our review provides a synthesis of the far‐reaching consequences that behavioural changes could have for marine ecosystems in a rapidly changing environment. Without considering the pervasive effects of climate change on animal behaviour we will limit our ability to forecast the impacts of ocean change and provide insights that can aid management strategies.     

Modelling the introduction and spread of non‐native species: international trade and climate change drive ragweed invasion

Biological invasions are a major driver of global change, for which models can attribute causes, assess impacts and guide management. However, invasion models typically focus on spread from known introduction points or non‐native distributions and ignore the transport processes by which species arrive. Here, we developed a simulation model to understand and describe plant invasion at a continental scale, integrating repeated transport through trade pathways, unintentional release events and the population dynamics and local anthropogenic dispersal that drive subsequent spread. We used the model to simulate the invasion of Europe by common ragweed (Ambrosia artemisiifolia), a globally invasive plant that causes serious harm as an aeroallergen and crop weed. Simulations starting in 1950 accurately reproduced ragweed's current distribution, including the presence of records in climatically unsuitable areas as a result of repeated introduction. Furthermore, the model outputs were strongly correlated with spatial and temporal patterns of ragweed pollen concentrations, which are fully independent of the calibration data. The model suggests that recent trends for warmer summers and increased volumes of international trade have accelerated the ragweed invasion. For the latter, long distance dispersal because of trade within the invaded continent is highlighted as a key invasion process, in addition to import from the native range. Biosecurity simulations, whereby transport through trade pathways is halted, showed that effective control is only achieved by early action targeting all relevant pathways. We conclude that invasion models would benefit from integrating introduction processes (transport and release) with spread dynamics, to better represent propagule pressure from native sources as well as mechanisms for long‐distance dispersal within invaded continents. Ultimately, such integration may facilitate better prediction of spatial and temporal variation in invasion risk and provide useful guidance for management strategies to reduce the impacts of invasion.     

Within‐group relatedness is correlated with colony‐level social structure and reproductive sharing in a social fish

In group‐living species, the degree of relatedness among group members often governs the extent of reproductive sharing, cooperation and conflict within a group. Kinship among group members can be shaped by the presence and location of neighbouring groups, as these provide dispersal or mating opportunities that can dilute kinship among current group members. Here, we assessed how within‐group relatedness varies with the density and position of neighbouring social groups in Neolamprologus pulcher, a colonial and group‐living cichlid fish. We used restriction site‐associated DNA sequencing (RADseq) methods to generate thousands of polymorphic SNPs. Relative to microsatellite data, RADseq data provided much tighter confidence intervals around our relatedness estimates. These data allowed us to document novel patterns of relatedness in relation to colony‐level social structure. First, the density of neighbouring groups was negatively correlated with relatedness between subordinates and dominant females within a group, but no such patterns were observed between subordinates and dominant males. Second, subordinates at the colony edge were less related to dominant males in their group than subordinates in the colony centre, suggesting a shorter breeding tenure for dominant males at the colony edge. Finally, subordinates who were closely related to their same‐sex dominant were more likely to reproduce, supporting some restraint models of reproductive skew. Collectively, these results demonstrate that within‐group relatedness is influenced by the broader social context, and variation between groups in the degree of relatedness between dominants and subordinates can be explained by both patterns of reproductive sharing and the nature of the social landscape.     

辽东山区次生林木本植物空间分布

森林木本植物的空间格局有助于揭示群落结构的形成机制与潜在的生态学过程,且对林分经营具有一定指导意义。在0—50 m尺度范围内综合分析了辽东山区4 hm2温带次生林样地多度10的树种空间格局。研究发现:(1)在完全随机零模型下,大部分树种呈现聚集格局,聚集格局树种的比例随尺度增加而降低;在32 m的较大尺度下,随尺度增加,随机和规则格局成为树种分布的主要形式;(2)在异质性泊松过程零模型下,55.9%的树种呈现随机格局,其余大部分树种在10 m的尺度下呈现聚集格局,且随尺度增加,规则格局成为主要形式;(3)在完全随机零模型下,树种属性(林层、径级和多度)显著地影响种群聚集度,而在异质性泊松过程零模型下,树种属性对种群聚集度不存在显著影响。综上,生境异质性、扩散限制和树种属性部分解释了辽东山区次生林木本植物空间分布格局,相对而言,生境异质性的效应更为突出。研究结果有助于揭示次生林群落生物多样性的维持机制。     

Natal dispersal in relation to population density and sex ratio in the field vole,Microtus agrestis

Summary In a sample of 240 juvenile field voles 8% of the males and 22% of the females reached sexual maturity within their natal home range. Among individuals retrapped as adults, 58% of males and 23% of females had dispersed, i.e. had moved more than one home range diameter. The mean distance moved for males (58.5 m) exceeded that for females (28.6 m). Male movement distances were negatively associated with total density, and with density of adult females, but not with male density. Female movements were not related to population density. There were no relation between sex ratio and distance moved. The distribution of distances moved for both males and females fit a geometrical distribution, suggesting the importance of competitive processes.     

Roosting Requirements of Two Frugivorous Bats (Sturnira lilium and Arbiteus intermedius) in Fragmented Neotropical Forest1

As tropical forest fragmentation accelerates, scientists are concerned with the loss of species, particularly those that play important ecological roles. Because bats play a vital role as the primary seed dispersers in cleared areas, maintaining healthy bat populations is critical to natural forest regeneration. Observations of foraging bats suggest that many Neotropical fruit‐eating species have fairly general habitat requirements and can forage in many different kinds of disturbed vegetation; however, their roosting requirements may be quite different. To test whether or not general foraging requirements are matched by equally broad roosting requirements, we used radiotelemetry to locate roost sites of two common frugivorous bat species (Sturnira lilium and Artibeus intermedius) in a fragmented forest in southeastern Mexico. Sturnira lilium roosted inside tree cavities and selected large‐diameter roost trees in remnant patches of mature forest. Fewer than 2 percent of trees surveyed had a mean diameter equal to or greater than roost trees used by . S. lilium, Artibeus intermedius roosted externally on branches and vines and under palm leaves and selected roost trees of much smaller diameter. Compared to random trees, roost trees chosen by A. intermedius were closer to neighboring taller trees and also closer in height to these trees. Such trees likely provide cryptic roosts beneath multiple overlapping crowns, with sufficient shelter from predators and the elements. While males of A. intermedius generally roosted alone in small trees within secondary forest, females roosted in small groups in larger trees within mature forest and commuted more than three times farther than males to reach their roost sites. Loss of mature forest could impair the ability of frugivorous bats to locate suitable roost sites. This could have a negative impact on bat populations, which in turn could decrease forest regeneration in impacted areas.     

Phylogeographic structure and cryptic speciation in the trans-Antarctic moss Pyrrhobryum mnioides

Abstract Many bryophyte species have distributions that span multiple continents. The hypotheses historically advanced to explain such distributions rely on either long-distance spore dispersal or slow rates of morphological evolution following ancient continental vicariance events. We use phylogenetic analyses of DNA sequence variation at three chloroplast loci ( atpB-rbcL spacer, rps4 gene, and trnL intron and 3'spacer) to examine these two hypotheses in the trans-Antarctic moss Pyrrhobryum mnioides. We find: (1) reciprocal monophyly of Australasian and South American populations, indicating a lack of intercontinental dispersal; (2) shared haplotypes between Australia and New Zealand, suggesting recent or ongoing migration across the Tasman Sea; and (3) reciprocal monophyly among Patagonian and neotropical populations, suggesting no recent migration along the Andes. These results corroborate experimental work suggesting that spore features may be critical determinants of species range. We use the mid-Miocene development of the Atacama Desert, 14 million years ago, to calibrate a molecular clock for the tree. The age of the trans-Antarctic disjunction is estimated to be 80 million years ago, consistent with Gondwanan vicariance, making it among the most ancient documented cases of cryptic speciation. These data are in accord with niche conservatism, but whether the morphological stasis is a product of stabilizing selection or phylogenetic constraint is unknown.