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The ultrasonic vocalizations (USVs) of rodents play a substantial role in the communication and interaction between individuals; exhibit a high degree of complexity; and are influenced by a multitude of developmental, environmental, and phylogenetic factors. The functions of USVs are mainly studied in laboratory mice or rats. However, the behavioral relevance of USVs in wild rodents is poorly studied. In this work, we systematically investigated the vocal repertoire of the wild mouse Mus caroli and wild rat Rattus losea in multiple social or non-social contexts, e.g., pup-isolation, juvenile-play, paired opposite-sex encounter, female–female interaction, social-exploring, or foot-shock treatment. Unlike the laboratory mice, M. caroli, whose USVs were recorded during pup-isolation and courtship behaviors, did not produce any vocal sounds during juvenile-play and female–female interactions. R. losea, similar to laboratory rats, emitted USVs in all test situations. We found higher peak frequencies of USVs in both these two wild rodent species than in laboratory animals. Moreover, the parameters and structures of USVs varied significantly across different social or non-social contexts even within each species, confirming the context-sensitivity and complexity of vocal signals in rodents. We also noted a striking difference in call types between these two species: no downward type occurred in M. caroli, but no upward type occurred in R. losea, thereby highlighting the interspecific difference of vocal signals among rodents. Thus, the present study presents behavioral foundations of the vocalization context in wild mice and wild rats, and contributes to revealing the behavioral significance of widely used USVs in rodents. [ABSTRACT FROM AUTHOR]

Grass carp and silver carp eggs have no swimming ability in the water-hardened phase and need to drift for tens or even hundreds of hours before complete incubation. A full comprehensive understanding of the settling and transport properties of eggs is crucial for the resource protection and invasion control of Four Major Chinese Carps (FMCCs) during their early life stages. Artificial eggs have been used extensively in previous field and flume experiments; however, our understanding of the settling and transport properties of real eggs in the water-hardened phase remains limited. In the present study, a series of column and flume experiments were conducted in stagnant and moving water, respectively. In light of the differences in settling characteristics, caution should be exercised when applying research results obtained from artificial eggs having the closest diameter and specific gravity as real eggs. Compared with grass carp and silver carp eggs in the water-hardening phase, egg diameters in the water-hardened phase were 36% and 33% greater, respectively, and egg hydrostatic settling velocities were 31% and 40% lower, respectively. Significant interspecific differences between the two species exist in terms of egg size and hydrostatic settling velocity. Based on linear mixed effects analysis of dominant transport trajectories and regression analysis between suspending rate and flow velocity, 0.30 m/s can be considered as critical drifting velocity in uniform flow. Adaptive management schemes are discussed to promote resource protection and invasion control of FMCCs during the early life stages. The results of the present study enhance our understanding of drifting egg movement and provide insights that could facilitate the comprehensive management of FMCCs.

Plantations are typically monocultures, which limits their sustainability. Therefore, understanding acclimatization strategies and resource use efficiencies in plant species and life forms aids the improvement of vegetation diversity and ecological functions. Here, 19 species from forest plantations in Fangshan, Beijing, China were studied. We determined their net photosynthetic (Pn), and transpiration rates (E), light response curve, stomatal conductance (gs), and leaf nitrogen (N) content. We analyzed the leaf N content (Nmass), specific leaf area (SLA), maximum net photosynthetic rate (Pnmax), water use (WUE), nitrogen use (NUE), and carbon use (CUE) efficiencies and connected them with both species and life forms. Pnmax, SLA, Nmass, WUE, NUE, and CUE significantly differed among species. Evergreen conifers had the lowest SLA and Nmass but the highest WUE and CUE. Evergreen coniferous trees had lower SLA, Nmass, Pnmax, and NUE but higher WUE than deciduous trees and shrubs. The SLA, Nmass, and Pnmax of nitrogen-fixing plants were the highest. A correlation analysis revealed that WUE was positively correlated with CUE and negatively correlated with NUE. Moreover, WUE was negatively correlated with Nmass and SLA. These insights into the adaptability differences of woody plant species and life forms provide a scientific basis for the selection of appropriate species for sustainable forest plantations. [ABSTRACT FROM AUTHOR]

The phenology of alpine grassland on the Qinghai–Tibet Plateau (QTP) is critical to regional climate change through climate–vegetation feedback. Although many studies have examined QTP vegetation dynamics and their climate sensitivities, the interspecific difference in the phenology response to climate change between alpine species is poorly understood. Here, we used a 30-year (1989–2018) record of in situ phenological observation for five typical alpine herbs (Elymus nutans , Kobresia pygmaea , Plantago asiatica , Puccinellia tenuiflora , and Scirpus distigmaticus) and associated climatic records at Henan Station in the eastern QTP to examine the species-level difference in spring and autumn phenology and then quantify their climate sensitivities. Our results show that with significantly warming, the green-up dates of herbs were insignificantly shifted, while the brown-off dates in four out of the five herbs were significantly delayed. Meanwhile, the interspecific difference in brown-off dates significantly increased at a rate of 0.62 days/annual from 1989 to 2016, which was three times larger than that in green-up dates (0.20 days/annual). These diverse rates were attributed to the different climate controls on spring and autumn phenology. In particular, green-up dates in most herbs were sensitive to mean surface temperature, while brown-off dates were sensitive to the night surface temperature. Furthermore, brown-off dates are less sensitive to the warming in high ecological niche (with higher herb height and aboveground biomass) herbs than low niche herbs (with lower herb height and aboveground biomass). The increased phenology interspecific difference highlights the complex responses of herbs to future climate change even under the same alpine environment and indicates a potential alternation in the plants community of alpine QTP, which may further influence the regional climate–vegetation feedback. [ABSTRACT FROM AUTHOR]

The phenology of alpine grassland on the Qinghai–Tibet Plateau (QTP) is critical to regional climate change through climate–vegetation feedback. Although many studies have examined QTP vegetation dynamics and their climate sensitivities, the interspecific difference in the phenology response to climate change between alpine species is poorly understood. Here, we used a 30-year (1989–2018) record of in situ phenological observation for five typical alpine herbs (Elymus nutans, Kobresia pygmaea, Plantago asiatica, Puccinellia tenuiflora, and Scirpus distigmaticus) and associated climatic records at Henan Station in the eastern QTP to examine the species-level difference in spring and autumn phenology and then quantify their climate sensitivities. Our results show that with significantly warming, the green-up dates of herbs were insignificantly shifted, while the brown-off dates in four out of the five herbs were significantly delayed. Meanwhile, the interspecific difference in brown-off dates significantly increased at a rate of 0.62 days/annual from 1989 to 2016, which was three times larger than that in green-up dates (0.20 days/annual). These diverse rates were attributed to the different climate controls on spring and autumn phenology. In particular, green-up dates in most herbs were sensitive to mean surface temperature, while brown-off dates were sensitive to the night surface temperature. Furthermore, brown-off dates are less sensitive to the warming in high ecological niche (with higher herb height and aboveground biomass) herbs than low niche herbs (with lower herb height and aboveground biomass). The increased phenology interspecific difference highlights the complex responses of herbs to future climate change even under the same alpine environment and indicates a potential alternation in the plants community of alpine QTP, which may further influence the regional climate–vegetation feedback.

Freshwater snails and submerged macrophytes are both important aquatic biological groups. The presence of freshwater snails might affect the growth of submerged macrophytes in term of their feeding behavior and metabolism. Bellamya aeruginosa (Reeve) is an important freshwater snail for most of Chinese waters and rarely grazes submerged macrophytes. We expected this snail species would benefit the growth of submerged macrophytes. We conducted a control experiment to study effects of nutrient enrichment in the water column and B. aeruginosa absence/presence on growth and carbon (C), nitrogen (N) and phosphorus (P) stoichiometric characteristics of three submerged macrophytes, Ceratophyllum demersum (L.), Hydrilla verticillata (L. f.) Royle, and Vallisneria natans (Lour.) Hara. The results indicated that both nutrient enrichment and B. aeruginosa presence affected the biomass and C, N, and P stoichiometric characteristics of submerged macrophytes. However, the effects of nutrient enrichment were relative larger than those of B. aeruginosa presence. B. aeruginosa could promote the biomass of V. natans in low nutrient levels but did not significantly affect the biomass of the other two macrophytes. B. aeruginosa presence increased the N contents of H. verticillata and V. natans, decreased the P contents of V. natans, and had negligible effects on C. demersum. Our study highlights that the effects of B. aeruginosa on submerged macrophytes were very complicated. More studies still should be done in order to give a scientific advice on how these two biological groups are combined used in the restoration of degraded aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a limiting element in many aquatic ecosystems. Excessive P input often leads to cyanobacterial bloom, thus triggering ecological imbalances and a series of environmental problems. Submerged macrophytes have a strong ability to absorb P and play important roles in maintaining aquatic ecosystem functions. However, the degree to which submerged macrophytes maintain their tissue P contents in various nutrient levels and the corresponding influencing factors are still not very clear. In this study, the stoichiometric characteristics and stoichiometric homeostasis of P in the aboveground and belowground parts of three submerged macrophytes, Vallisneria natans (Lour.) Hara, Hydrilla verticillata (L.f.) Royle, and Ceratophyllum demersum (L.), with great differences in growth forms, were studied under different growth times and nutrient levels via laboratory experiments. The results showed that the water conductivity, turbidity, and chlorophyll content increased significantly with the increasing nutrient levels. The variation of species, organ, growth time, and nutrient level could significantly affect the P contents of submerged macrophytes. Among these factors, the variance contribution rates caused by the differences of nutrient levels in water column were the highest at more than 50%. The P stoichiometric homeostasis index (HP) in the belowground parts of the three submerged macrophytes was higher than that of the aboveground parts. The HP decreased by the growth time; the HP of V. natans was significantly higher than those of H. verticillata and C. demersum. In summary, the P stoichiometric homeostasis in submerged macrophytes could reflect their responses to environmental changes, and the P content of submerged macrophytes was an indicator of the bioavailability of external P. H. verticillata exhibited a high growth rate and a high accumulation of P content, making it the most suitable species in this study for removing large amounts of P from water in a short term.

• A series of column and flume experiments address the settling and transport properties of grass carp and silver carp eggs in the water-hardened phase. • Phase-specific and inter-specific differences exist in egg size and hydrostatic settling velocity. • The critical drifting velocity of grass carp and silver carp eggs can be considered as 0.30 m/s in uniform flow. • Adaptive management schemes are discussed to promote resource protection and invasion control of FMCCs during the early life stages. Grass carp and silver carp eggs have no swimming ability in the water-hardened phase and need to drift for tens or even hundreds of hours before complete incubation. A full comprehensive understanding of the settling and transport properties of eggs is crucial for the resource protection and invasion control of Four Major Chinese Carps (FMCCs) during their early life stages. Artificial eggs have been used extensively in previous field and flume experiments; however, our understanding of the settling and transport properties of real eggs in the water-hardened phase remains limited. In the present study, a series of column and flume experiments were conducted in stagnant and moving water, respectively. In light of the differences in settling characteristics, caution should be exercised when applying research results obtained from artificial eggs having the closest diameter and specific gravity as real eggs. Compared with grass carp and silver carp eggs in the water-hardening phase, egg diameters in the water-hardened phase were 36% and 33% greater, respectively, and egg hydrostatic settling velocities were 31% and 40% lower, respectively. Significant interspecific differences between the two species exist in terms of egg size and hydrostatic settling velocity. Based on linear mixed effects analysis of dominant transport trajectories and regression analysis between suspending rate and flow velocity, 0.30 m/s can be considered as critical drifting velocity in uniform flow. Adaptive management schemes are discussed to promote resource protection and invasion control of FMCCs during the early life stages. The results of the present study enhance our understanding of drifting egg movement and provide insights that could facilitate the comprehensive management of FMCCs. [ABSTRACT FROM AUTHOR]

Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing). The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight) defined as the grazing ability index (GAI). There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni). Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate) was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests the importance of various size of parrotfishes with diverse feeding modes to maintain healthy coral reef ecosystems.

Common buckwheat (Fagopyrum esculentum Moench cv. Tsushima) and Tartary buckwheat (F. tataricum (L.) Gaertn. cv. Pontivy) were grown in a nutrient solution with or without added NaCl to investigate interspecific differences in their responses to salinity, based on their dry-matter production. The mechanism of salt tolerance was also studied. Addition of 100 mM NaCl to the culture solution (salt treatment) lowered the plant growth rate to 48% and 16% of the control in Tsushima and Pontivy, respectively, and decreased the net assimilation rate and mean leaf area of Pontivy more severely than in Tsushima. The salt treatment decreased the leaf growth rate and leaf area per leaf to 30% and 72% of the control, respectively, in Tsushima, and to 12% and 52%, respectively, in Pontivy. It decreased the photosynthetic rate to 67% and 35% of the control, and stomatal conductance to 25% and 15% of the control in Tsushima and Pontivy, respectively. It also decreased the transpiration rate to 41% and 30% of the control in Tsushima and Pontivy, respectively, and increased the wateruse efficiency 1.6 times in Tsushima, but did not influence the wateruse efficiency in Pontivy. In the saline solution, the accumulation of Na+ in leaves and stem was greater in Pontivy than in Tsushima, but that in the roots, was greater in Tsushima than in Pontivy. In both species, Na+ accumulated rapidly in the leaves after removal of the roots in the saline solution. We conclude that the difference in salt tolerance between common and Tartary buckwheat may result from the difference in accumulation of Na+ in leaves and absorption of Na+ by the roots.

Common buckwheat (Fagopyrum esculentum Moench cv. Shinano No.1) and Tartary buckwheat (F. tataricum (L.) Gaertn. cv. Nepal) were grown in pots to examine their responses to soil flooding. Flooding treatment was carried out during the early growth stage by completely submerging the pots in a nutrient solution from 12 to 36 days after sowing. The plant growth rate, relative growth rate and mean leaf area under the flooding treatment were reduced to 72, 90 and 83% of the control, respectively, in Shinano No.1, and to 29, 71 and 45% of the control, respectively, in Nepal. The excess moisture stress had no effect on the net assimilation rate (NAR) in Shinano No.1, but lowered the NAR to 68% of that in the control in Nepal. Excess moisture stress decreased the total leaf area to 76 and 34% of the control in Shinano No.1 and Nepal, respectively. Leaf growth rate, number of leaves and leaf area per leaf, which influenced the total leaf area, were reduced by the excess soil moisture. The relative water content of leaves was unchanged in Shinano No.1, but was decreased in Nepal. Reduction in bleeding from the cut end of stem due to flooding was greater in Nepal than in Shinano No.1. Excess moisture stress reduced the K+ concentration of the stem and increased the Na+ concentration of leaves, stem and roots more strongly in Nepal than in Shinano No.1. Development of adventitious roots in the surface layer of the nutrient solution was better in Shinano No.1 than in Nepal. In conclusion, Shinano No.1 (common buckwheat) had a stronger tolerance to excess soil moisture than Nepal (Tartary buckwheat). In Shinano No. 1, leaf growth and photosynthetic rate were not markedly affected and the capacity of absorbing water and nutrients was retained by developing adventitious roots in the solution above the surface of the soil keeping proper physiological activity under excess moisture conditions.

The growth of crown and lateral roots emerged from the excised phytomers of pearl millet (Pennisetum typhoideum Rich.), barnyard millet (Echinochloa frumentacea Link.) and maize (Zea mays L.) was studied under normal and low osmotic potential conditions. The plants were grown in two solutions with osmotic potentials of –0.02 and –0.54 MPa for 6 days. The relative growth rate of the roots in total length (RGRL) , was not affected by osmotic stress in pearl and barnyard millets, but that in stressed maize was reduced to 64% of the control. Similarly, the relative growth rate of the roots in dry weight (RGRW), was not affected by osmotic stress in pearl and barnyard millets, but significantly reduced in maize. Osmotic stress increased the specific root length of the lateral roots in pearl and barnyard millets, but did not affect that of maize. The photosynthetic rate (Pr) in the two millets was decreased to ca. 60% of the control by the stress, and that in maize was reduced to 21%. Under the stress, Pr in the three species was limited mainly by low stomatal conductance, but no clear relationship was found between Pr and osmotic adjustment of the leaf. The relative water content of the leaf was lower in maize than in the two millets. The resistance to water flow through the phytomer (R) was significantly increased by osmotic stress in maize, but not significantly in the two millets. The mean root length (RL) was decreased by the stress in maize, but not in the two millets. The maintenance of RGRL in the two millets was associated with sustained R, RL and also with the maintenance of Pr and allocation of assimilates to roots.

Dendroecological techniques were used to examine the relationships between topographic aspects, climate factors and radial growth of Picea meyeri and Larix principis-rupprechtii in Luyashan Mountains, North-Central China. Four sites were selected at timberline and totally 67 trees and 134 cores were collected. Pearson correlation and regression surface analysis were conducted to reveal the growth-climate relationships. The results indicated that the two species both showed significant negative correlations with temperature during preceding November on the two topographic aspects. On both slope aspects, growth of P. meyeri exhibited significant negative correlations with precipitation in current June, whereas growth of L. principis-rupprechtii showed significant negative correlations with precipitation in preceding September. On north-facing slope, tree growth was limited by low temperature in early growing season, which not shown on south-facing slope. If climate warming continues, L. principis-rupprechtii may be more favored and a reverse between relationships with temperature and precipitation maybe occur in growth of trees. Treeline position on the north-facing slope may possess a greater potential for elevation shifting than the south-facing slope. Our results supply useful information for discussing the potential effect of future climate on the forest growth in North-Central China. [ABSTRACT FROM AUTHOR]

•Investigation of responses of meristems to environmental conditions is important for understanding the mechanisms and consequences of plant phenotypic plasticity. Here, we examined how meristem plasticity to light and soil nutrients affected leaf growth and relative growth rate (RGR) in fast- and slow-growing Festuca grass species. •Activity in shoot apical meristems was measured by leaf appearance rate, and that in leaf meristems by the duration and rate of cell production, which was further divided into single cell cycle time and the number of dividing cells. •Light and soil nutrients affected activity in shoot apical meristems similarly. The high nutrient supply increased the number of dividing cells, which was responsible for enhancement of cell production rate; shaded conditions extended the duration of cell production. As a result, leaf length increased under high nutrient and shaded conditions. The RGR was correlated positively with the total meristem size of the shoot under a low nutrient supply, implying inhibition of RGR by cell production under nutrient-limited conditions. Fast-growing species were more plastic for cell production rate and specific leaf area (SLA) but less plastic for RGR than slow-growing species. •This study demonstrates that meristem plasticity plays key roles in characterizing environmental responses of plant species. [ABSTRACT FROM AUTHOR]

Seed dispersal is a key process within community dynamics. The spatial and temporal variations of seed dispersal and the interspecific differences are crucial for understanding species coexistence and community dynamics. This might also hold for the mixed evergreen broadleaved and deciduous forests in the mountains of subtropical China, but until now little existing knowledge is available for this question. In 2001, we chose to monitor the seed rain process of our mixed evergreen broad-leaved and deciduous forest communities in Mount Dalaoling National Forest Park, Yichang, Hubei Province, China. The preliminary analyses show obvious variations in seed rain density, species compositions and timing of seed rain among four communities. The average seed rain densities of the four communities are 2.43 ± 5.15, 54.13 ± 182.75, 10.05 ± 19.30 and 24.91 ± 58.86 inds./m2 , respectively; about one tenth the values in other studies in subtropical forests of China. In each community, the seed production is dominated by a limited number of species, and the contributions from the others are generally minor. Fecundity of evergreen broadleaved tree species is weaker than deciduous species. The seed rain of four communities begins earlier than September, and stops before December, peaking from early September to late October. The beginning date, ending date and peak times of seed rain are extensively varied among the species, indicating different types of dispersal strategies. According to the existing data, the timing of seed rain is not determined by the climate conditions in the same period, while the density of seed rain may be affected by the disturbances of weather variations at a finer temporal resolution. [ABSTRACT FROM AUTHOR]

We present a theoretical model to quantify the influence of diversity on productivity and nutrient acquisition in plant communities during exponential growth. The model fractionates diversity into three components, namely species richness (S), species evenness (E) and the degree of difference between species (D). The influence of each of these components is assessed individually: S is varied by changing the number of species, E by changing their population size, and D by changing the range of species traits critical to productivity (specific nutrient uptake rate, σr, or nutrient use efficiency, NUE). D was quantified as the coefficient of variation of σr or NUE. All three components of diversity enhance the biomass and nutrient stocks in the community, but the response patterns are different. Species richness has a saturating influence, whereas effects of E and D are linear and exponential, respectively. In all cases the non-linear dependence of productivity and nutrient acquisition on σr and NUE during exponential growth was the single mechanism underlying these effects. This causes the presence of plants with extreme traits to promote productivity, and S, E and D all affect the abundance and/or intensity of these extremes. The model offers a framework to explain differences between experimental observations, and suggests a concept of diversity where S and E are structural components and D a qualitative or functional component, which modulates the influence of the two others. We propose to explicitly recognize D as an integral constituent of plant diversity in future studies. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is a limiting element in many aquatic ecosystems. Excessive P input often leads to cyanobacterial bloom, thus triggering ecological imbalances and a series of environmental problems. Submerged macrophytes have a strong ability to absorb P and play important roles in maintaining aquatic ecosystem functions. However, the degree to which submerged macrophytes maintain their tissue P contents in various nutrient levels and the corresponding influencing factors are still not very clear. In this study, the stoichiometric characteristics and stoichiometric homeostasis of P in the aboveground and belowground parts of three submerged macrophytes, Vallisneria natans (Lour.) Hara, Hydrilla verticillata (L.f.) Royle, and Ceratophyllum demersum (L.), with great differences in growth forms, were studied under different growth times and nutrient levels via laboratory experiments. The results showed that the water conductivity, turbidity, and chlorophyll content increased significantly with the increasing nutrient levels. The variation of species, organ, growth time, and nutrient level could significantly affect the P contents of submerged macrophytes. Among these factors, the variance contribution rates caused by the differences of nutrient levels in water column were the highest at more than 50%. The P stoichiometric homeostasis index ( H P ) in the belowground parts of the three submerged macrophytes was higher than that of the aboveground parts. The H P decreased by the growth time; the H P of V. natans was significantly higher than those of H. verticillata and C. demersum . In summary, the P stoichiometric homeostasis in submerged macrophytes could reflect their responses to environmental changes, and the P content of submerged macrophytes was an indicator of the bioavailability of external P. H. verticillata exhibited a high growth rate and a high accumulation of P content, making it the most suitable species in this study for removing large amounts of P from water in a short term.

Parrotfishes (family Labridae: Scarini) are regarded to have important roles for maintaining the ecosystem balance in coral reefs due to their removal of organic matter and calcic substrates by grazing. The purpose of the present study was to clarify the interspecific differences in grazing ability of five parrotfish species (Chlorurus sordidus, C. bowersi, Scarus rivulatus, S. niger and S. forsteni) in relation to interspecific differences in jaw-lever mechanics and the relative weight of the adductor mandibulae (muscles operating jaw closing). The grazing ability was calculated by using stomach contents (CaCO3 weight/organic matter weight) defined as the grazing ability index (GAI). There were significant interspecific differences in GAI (C. sordidus = C. bowersi > S. rivulatus > S. niger = S. forsteni). Teeth of C. sordidus and C. bowersi were protrusive-shape whereas teeth of S. rivulatus, S. niger and S. forsteni were flat-shape. C. sordidus and C. bowersihave jaw-lever mechanics producing a greater biting force and have a larger weight of adductor mandibulae. S. rivulatus has jaw-lever mechanics producing a greater biting force but a smaller weight of adductor mandibulae that produce an intermediate biting force. In contrast, S. niger and S. forsteni have jaw-lever mechanics producing a lesser biting force and have a smaller weight of adductor mandibulae. Feeding rates and foray size of S. rivulatus, S. niger and S. forsteni were greater than C. sordidus and C. bowersi. The degree in bioerosion (GAI × feeding rate) was the largest for S. rivulatusand the smallest for S. forsteni. The degree in bioerosion for C. sordidus was larger than S. niger whereas relatively equal between C. bowersi and S. niger. These results suggest that interspecific difference in GAI was explained by interspecific differences in teeth shape, jaw-lever mechanics and relative weight of adductor mandibulae. The interspecific difference in the degree of bioerosion suggests the importance of various size of parrotfishes with diverse feeding modes to maintain healthy coral reef ecosystems., Competing Interests: The author declares there are no competing interests.