Do Species with Large Capitula Suffer Higher Rates of Predispersal Seed Loss than Species with Small Capitula? A Field Survey of 34 Asteraceae Species in an Alpine Meadow

Premise of research.Capitulum (flowerhead) size varies widely across Asteraceae species, even within the same community. Previous work has suggested that capitulum variation among species results from the contrasting selection processes by pollinators for larger capitulum and by predispersal seed (achene) predators for smaller capitulum. However, this explanation is contested by the finding across Asteraceae that seed loss rate per infested capitulum is lower in species with large capitula, such that large capitula do not necessarily suffer higher overall seed loss compared to species with small capitula.Methodology.We measured the capitulum size, seed size, plant aboveground biomass, seed loss per infested capitulum, and capitula infestation rates for 34 Asteraceae species in an alpine meadow to determine whether there is a capitulum size-dependent effect on overall predispersal seed loss.Pivotal results.The data show that the seed loss rate per infested capitulum decreased (but capitula infestation rate increased) with increasing capitulum size. Nevertheless, at the species level, the overall predispersal seed loss rate (seed loss rate per infested capitulum x capitula infestation rate) was higher in species with larger capitula compared to those with smaller capitula. The disadvantage of producing larger capitula was partly compensated for by the competitive advantage conferred by producing large individual seeds and greater aboveground biomass.Conclusions.Species with large capitula suffer higher rates of overall predispersal seed loss, which is consistent with the hypothesis that predispersal seed predators affect capitulum size. We suggest that biological interactions between plants and animals (e.g., pollinators and seed predators) contribute to the great diversity of capitulum size among Asteraceae species

Tadpole survival (A) and body fresh weight (B) in four treatments including warmed and predator present (W+P+), ambient and predator present (W−P+), warmed and predator absent (W+P−), and ambient and predator absent (W−P−).

<p>The asterisk denotes a statistically significant difference between warmed and ambient treatments at the 0.05 level, as derived from a two-way ANOVA followed by <i>post hoc</i> Tukey's test on the observation day. Data are means ±1SE.</p

The scaling relationships between tail length and body length (A and B) in the presence and absence of predators.

<p>In (A) the warmed and ambient treatments share common slope and y-intercept, but the warmed has a significant shift along the common slope. In (B), the warmed and ambient treatments share a common slope, but y-intercept is significantly higher in the warmed than the ambient. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098252#pone.0098252.s004" target="_blank">Appendix S4</a> for the equation fitting and see text for the difference between treatments. W+P+, warmed and predator present; W−P+, ambient and predator present; W+P−, warmed and predator absent; W−P−, ambient and predator absent.</p

Artificial Warming Facilitates Growth but Not Survival of Plateau Frog (<i>Rana kukunoris</i>) Tadpoles in Presence of Gape-Limited Predatory Beetles

<div><p>Background</p><p>Global warming has been frequently demonstrated to increase growth rate in larval amphibians that have considerable phenotypic plasticity; this may lead to an increase in larval survival because large larvae are less likely to be captured by gape-limited predators. This study is to test whether warming could improve tadpole growth and thereby enhance the tadpole survival in plateau frog <i>Rana kukunoris</i>.</p><p>Methodology</p><p>We conducted an experiment involving growing tadpoles under two contrasting temperatures, i.e. ambient temperature vs. warming by 3.8°C, with and without their major predators – the gape-limited predaceous diving beetles <i>Agabus</i> sp. in eastern Tibetan Plateau, in a factorial arrangement. We recorded the survival and measured body fresh weight and morphological characteristics of the tadpoles.</p><p>Principal Findings</p><p>Warming significantly increased body fresh weight in the presence of predators after three weeks of treatments. However, the predators imposed significant and similar effects on the survival of tadpoles under both ambient and elevated temperatures, with the effects mostly occurring in the first three weeks of the experiment. Changes in the body form, i.e. the greater whole length at a given fresh weight and the longer tail at a given body length, could have acted as mechanisms of defense and escape for the tadpoles.</p><p>Conclusions/Significance</p><p>Warming did not increase tadpole survival with or without presence of predators. Moreover, an increased growth rate (due to warming in the presence of predators) was not a major factor contributing to the tadpole survival. We postulate that even if warming increases the tadpole growth rate in the plateau frog, it does not necessarily improve their survival in the presence of gape-limited predators.</p></div

List of bird species in the breeding season of 2020 in the Zhoushan Archipelago, China

List of bird species in the breeding season of 2020 in the Zhoushan Archipelago, China Duorun Wang1, #, Yuhao Zhao1, #, Shupei Tang1, Xiangxu Liu1, Wande Li1, Peng Han1, Di Zeng1, Yangheshan Yang1, Guangpeng Wei1, Yi Kang1, Xingfeng Si1* 1 Institute of Eco-Chongming (IEC), Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; # These authors contributed equally to this work and should be considered co-first authors; * Corresponding author: Xingfeng Si: [email protected] We surveyed bird assemblages on study islands in Zhoushan Archipelago in the breeding season of 2020 (from April to June). We setup transects on each island to cover various habitat types for birds except highly urbanized regions (i.e., cities and towns). For the largest island (Island 1: Zhoushan Island), we set eight transects. For the rest of study islands, we set one, two, or four transects that the number of transects was based on the area and land-use types of study islands. We used Global Positioning System (GPS) to record the position and the length of each transect. The transect length is 2 km on most study islands. However, the transect length is restricted to 1 km for several small islands, as the steep terrain (e.g., cliffs near the edges) does not allow us to set a 2-km transect. For bird surveys, at least two well-trained surveyors walked at a constant speed (ca. 1.5 km/h) along transects and recorded the identities and abundances of all birds heard and seen. Bird surveys were conducted two hours after sunrise and one hours before sunset, and the overall surveying time was restricted to two hours in each survey. We only conducted bird surveys on days with good weather conditions, excluding heavy raining or strong windy days. All transects were surveyed twice which is the maximum survey effort we can afford due to the large region of the Zhoushan Archipelago, the limited transportations in this region and the relatively short period of the breeding season. Surveyors walked the transects in a random order by inversing the starting point to avoid survey biases.</p