Evaluation of methods to estimate foliage density in the understorey of a tropical evergreen forest

Foliage density and leaf area index are important vegetation structure variables. They can be measured by several methods but few have been tested in tropical forests which have high structural heterogeneity.In this study, foliage density estimates by two indirect methods, the point quadrat and photographic methods,were compared with those obtained by direct leaf counts in the understorey of a wet evergreen forest in southern India. The point quadrat method has a tendency to overestimate, whereas the photographic method consistently and significantly underestimates foliage density. There was stratification within the understorey, with areas close to the ground having higher foliage densities

Errors in communication

I wish to bring to your notice a few errors in the meeting report by Anil Kumar 1. In the first and second columns of p. 1399 are described the oral presentations that were made by Caitlin O’Connell-Rodwellon seismic communication in elephants and of Andrea (not Andrew) M. Sim-mons on acoustic methods for studying frog choruses, two women scientists who have mysteriously undergone a gendertrans formation in Anil Kumar’s report! Not only in the interest of accuracy in scientific reporting but also as a woman scientist, I take strong exception to these errors

Species Concepts, Species Boundaries and Species identification: A View from the Tropics

Species Concepts, Species Boundaries and Species Identification: A View from the Tropic

Data from: Spatio-temporal dynamics of field cricket calling behaviour: implications for female mate search and mate choice

Amount of calling activity (calling effort) is a strong determinant of male mating success in species such as orthopterans and anurans that use acoustic communication in the context of mating behaviour. While many studies in crickets have investigated the determinants of calling effort, patterns of variability in male calling effort in natural choruses remain largely unexplored. Within-individual variability in calling activity across multiple nights of calling can influence female mate search and mate choice strategies. Moreover, calling site fidelity across multiple nights of calling can also affect the female mate sampling strategy. We therefore investigated the spatio-temporal dynamics of acoustic signaling behaviour in a wild population of the field cricket species Plebeiogryllus guttiventris. We first studied the consistency of calling activity by quantifying variation in male calling effort across multiple nights of calling using repeatability analysis. Callers were inconsistent in their calling effort across nights and did not optimize nightly calling effort to increase their total number of nights spent calling. We also estimated calling site fidelity of males across multiple nights by quantifying movement of callers. Callers frequently changed their calling sites across calling nights with substantial displacement but without any significant directionality. Finally, we investigated trade-offs between within-night calling effort and energetically expensive calling song features such as call intensity and chirp rate. Calling effort was not correlated with any of the calling song features, suggesting that energetically expensive song features do not constrain male calling effort. The two key features of signaling behaviour, calling effort and call intensity, which determine the duration and spatial coverage of the sexual signal, are therefore uncorrelated and function independently

Low-Resolution Calling Effort Scans

Low-resolution calling effort scans for 31 nights (individual files). The first column refers to the unique 3-letter colour codes of individuals followed by the time at which the individuals were first sighted (2nd column). The next set of columns, except the last two, represent the calling activity marked in binary (1 for calling and 0 for non-calling), with headings indicating the start of scan sampling. The final two columns represent the distance (r) and angle (theta) of the calling site from a given reference point

CallingSongFeatures

5-syllable chirp duration, 5-syllable chirp period and number of 2-syllable chirps of the P.guttiventris calling song recorded from different individuals

High-Resolution_CallingEffort

High resolution calling effort scans of individuals. The first row contains the individual ID (unique 3-colour codes). The second row refers to the night number corresponding to the low-resolution scans(hence the file number). '0' means that those individuals were found outside of the 31 nights when low-resolution scan sampling was conducted. The third row depicts the Sound Pressure Level (SPL). The fourth row contains the starting time of high-resolution calling effort sampling. The following rows contain the calling effort data coded in binary

Male and Female Stridulation in an Indian Weta (Orthoptera: Anostostomatidae)

We present the first description of the calls and stridulatory structures of males and females of an Indian weta species from the Western Ghats of Southern India. Calls of males and females produced by femoro-abdominal stridulation were recorded and call features such as chirp duration, chirp period, syllable period and syllable duration were characterised. The calls of males were highly stereotyped with regular chirp periods and durations whereas chirp rates in the female calls were more variable. The number of syllables per chirp was constant for males and females and the fine temporal features such as syllable periods and syllable durations showed low inter-individual variation in both males and females. The arrangement of femoral stridulatory structures was different from the previously described anostostomatid species. The high stereotypy of calls of males and females indicates that the signal could serve for identification of species and sex

The opportunity for sampling: the ecological context of female mate choice

Female mate choice decisions, which influence sexual selection, involve complex interactions between the 2 sexes and the environment. Theoretical models predict that male movement and spacing in the field should influence female sampling tactics, and in turn, females should drive the evolution of male movement and spacing to sample them optimally. Theoretically, simultaneous sampling of males using the best-of-n or comparative Bayes strategy should yield maximum mating benefits to females. We examined the ecological context of female mate sampling based on acoustic signals in the tree cricket Oecanthus henryi to determine whether the conditions for such optimal strategies were met in the field. These strategies involve recall of the quality and location of individual males, which in turn requires male positions to be stable within a night. Calling males rarely moved within a night, potentially enabling female sampling strategies that require recall. To examine the possibility of simultaneous acoustic sampling of males, we estimated male acoustic active spaces using information on male spacing, call transmission, and female hearing threshold. Males were found to be spaced far apart, and active space overlap was rare. We then examined female sampling scenarios by studying female spacing relative to male acoustic active spaces. Only 15% of sampled females could hear multiple males, suggesting that simultaneous mate sampling is rare in the field. Moreover, the relatively large distances between calling males suggest high search costs, which may favor threshold strategies that do not require memory