Summary Flower and seed production of plants can be greatly influenced by both natural climatic oscillations and local weather extremes. However, owing to the rarity of long‐term monitoring studies conducted at a sufficient temporal scale to capture climatic oscillations and the unpredictability of extreme weather events, evidence that demonstrates how these two external forcings act in concert to drive plant reproduction remains scarce. In addition, considerable variation in species' phenological responses to the external climatic forcings was often observed. Phylogenetic relationships may mediate this interspecific variation, but previous studies yielded inconsistent results when testing this hypothesis. We monitored the flower and seed production in a subtropical rain forest, Fushan, Taiwan (24°45′N, 121°35′E), for over 10 years (since September 2002). In March 2005, a record low temperature (−1.3 °C) occurred at Fushan and caused great frost damage to plants. We used weekly phenological records and long‐term meteorological data to assess the effects of climatic fluctuations and extreme weather event on plant reproductive output. We show that the El Niño Southern Oscillation (ENSO) indices, which integrated local climatic variables at Fushan over several months, were strongly associated with flower and seed production. The 2005 spring frost also had long‐lasting effects on the flower and seed production of several species. In particular, we detected phylogenetic signals in the relationships between phenological responses of flowering production and several climatic variables (maximum temperature, irradiance and ENSO34 index). By contrast, the relationships between seed production and climatic variables, as well as phenological responses to the frost event, did not exhibit a phylogenetic signal. Synthesis. Our findings add to the growing evidence that together the natural climatic oscillation (ENSO) and the extreme weather event (frost) determined the temporal variation in flower and seed production. In addition, phylogenetically closely related species resembled each other in their flowering responses to abiotic variation in this subtropical rain forest. Improved understanding of these abiotic and biotic interactions may help predicting population‐ and community‐level phenological responses under future climate changes.
The world’s coral reefs are experiencing increasing volatility in coral cover, largely because of anthropogenic environmental change, highlighting the need to understand how such volatility will influence the structure and dynamics of reef assemblages. These changes may influence not only richness or evenness but also the temporal stability of species’ relative abundances (temporal beta-diversity). Here, we analyzed reef fish assemblage time series from the Great Barrier Reef to show that, overall, 75% of the variance in abundance among species was attributable to persistent differences in species’ long-term mean abundances. However, the relative importance of stochastic fluctuations in abundance was higher on reefs that experienced greater volatility in coral cover, whereas it did not vary with drivers of alpha-diversity. These findings imply that increased coral cover volatility decreases temporal stability in relative abundances of fishes, a transformation that is not detectable from static measures of biodiversity.
The mechanism underlying species abundance distribution (SAD), particularly the characteristics of ''excess of rare species,'' remains controversial. The current equilibrium theory cannot explain the transient dynamics of SAD, which is essential for predicting biodiversity response to environmental changes. Using a unique 32-yr-long phytoplankton community data set from a pelagic site of Lake Biwa, Japan, we show that the dynamics of functional groups driven by environmental variation explain the excess of rare species over time. First, most of the rare species belong to the littoral group supplied through dispersal, whereas the common species belong to the pelagic group. Second, the littoral group was negatively influenced by environmental changes (i.e., lake warming, water-level manipulation, and partial re-oligotrophication), mechanistically explaining truncation of the excess of rare species in the SAD associated with biodiversity loss in Lake Biwa. Our findings imply the significance of an ecological trait-based approach for SAD theory and managing biodiversity in a changing environment.
Anthropogenic structures, such as wall surfaces, may change the acoustic environment for signals transmitted by animals, creating novel environments that animals must either adapt to or abandon. Animals can potentially use those structures to manipulate sound characteristics. In many anuran species, successful reproduction depends on long-range propagation and perception of advertisement calls. Callers may select natural perches or human-made objects to assist call propagation. Male Mientien tree frogs Kurixalus idiootocus frequently perch and call in roadside concrete drainages -miniature urban canyons. We used a combination of field and indoor experiments to test two hypotheses: (1) transmission of calls emitted inside drains is enhanced; (2) males selected perches inside drains that facilitated call transmission. A field survey indicated that male Mientien tree frogs preferred calling inside rather than outside drains. A playback showed that calls emitted from inside drains were enhanced in both amplitude and note duration. In an indoor experiment using a replica of a concrete drain, males preferred one particular type of call perch. However, we found no difference in sound properties between random locations inside the drain model and the perch location preferred by calling males.Storm drains enhance calls of a tree frog W.-H. Tan et al.
An ecological community is commonly composed of a few abundant species and a large number of rare species. However, the mechanism underlying this universal community structure remains controversial, particularly regarding how species abundances can dynamically respond to environmental change. Here, we provide a species-trait-based explanation. Using >30 year long phytoplankton time series data from Lake Biwa, Japan, we found those rare species that adapt to littoral habitats disappeared in the late 1980s in response to lake warming and changes of water level variations and trophic states. This functional response explained the rise and fall of rare species in structuring community over time.October 2014 457
Environmental fluctuations are becoming increasingly volatile in many ecosystems, highlighting the need to better understand how stochastic and deterministic processes shape patterns of commonness and rarity, particularly in high-diversity systems like coral reefs. Here, we analyze reef fish time-series across the Great Barrier Reef to show that approximately 75% of the variance in relative species abundance is attributable to deterministic, intrinsic species differences. Nevertheless, the relative importance of stochastic factors is markedly higher on reefs that have experienced stronger coral cover volatility. By contrast, α-diversity and species composition are independent of coral cover volatility but depend on environmental gradients. Our findings imply that increased environmental volatility on coral reefs erodes assemblage’s niche structure, an erosion that is not detectable from static measures of biodiversity.One-Sentence SummaryCoral cover volatility modulates how stochastic and deterministic processes shape commonness and rarity in coral reef fishes.
The Point Intercept Transect (PIT) method has commonly been used in recent decades for estimating the status of coral reef benthic communities. It is a simple method that is efficiently performed underwater, as benthic components are recorded only as presence or absence at specific interval points along transects. Therefore, PIT is also popular in citizen science activities such as Reef Check programs. Longer intervals are commonly associated with longer transects, yet sampling interval length can significantly influence benthic coverage calculations. Despite this, the relative accuracy of longer or shorter intervals related to transect length has not been tested for PIT. In this study, we tested the optimum intervals of PIT for several commonly used transect lengths using the bootstrap method on empirical data collected on tropical coral reefs and non-reefal coral communities. Our results recommend fine intervals of 10 cm or shorter, depending on the length of the transect, to increase the accuracy of estimating benthic community status on coral reefs. Permanent transects should also be considered in long-term monitoring programs to improve data quality.
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