Temporal Niche Overlap Research Articles

Niche characteristics of rodents by diverse disturbance in Alashan desert, Inner Mongolia, China

Four diverse disturbance types, namely, farmland, rotationally grazed grassland, overgrazed grassland and forbidden grazing grassland, were identified in the Alashan desert region of Inner Mongolia. Rodents were sampled in April, July and October in 2002 and 2003 using the trap-day method. Their spatial and temporal niches among the four disturbance types were assessed using the Shannon-Wiener niche breadth index and the Pianka niche overlap index. The Shannon-Wiener niche breadth index was the highest for Allactaga sibirica and Meriones meridianus (0.925 and 0.908, respectively), intermediate for Cricetulus eversmanni, Phodopus roborovskii and Citellus dauricus (0.789, 0.782 and 0.711, respectively), and lowest for Cardiocranius paradoxus (0.003). The Pianka niche overlap indices of six-paired species were the highest and varied from 0.900 to 1.000, suggesting their spatial niche overlapped almost completely. Conversely, the spatial niche overlap index for Meriones unguiculatus, Cardiocranius paradoxus, and Salpingotus kozlovi was zero, thus indicating a complete absence of competition among them. In addition, the temporal niche breadth and overlap indices varied greatly in relation to disturbance types and season. The level of temporal niche overlap in spring and autumn was low while in summer it was high. For all disturbance types and for each season, the temporal niche overlap index of Meriones meridianus and Cricetulus barabansis was always highest but for Meriones unguiculatus and Salpingotus kozlovi always lowest.

Ciclos de actividad diaria y estacional de un gremio de saurios en las dunas de arena de Viesca, Coahuila, México

In 2002, daily and seasonal activity patterns of the lizards Uta stejnegeri, Uma exsul, and Aspidoscelis marmorata were evaluated in a dune habitat in the southwestern portion of Coahuila, Mexico. Methods included surveying a 500 m transect once per hour between 0700 and 1900 for 7 days each season during the spring, summer and fall. The number of active lizards, air and substrate temperatures, and relative humidity were recorded. A standardized Levins Index and Pianka's method were used to measure temporal niche breadth and overlap, respectively. In each of the 3 seasons, U. stejnegeri was active earlier than U. exsul, and U. exsul was active before A. marmorata. The 3 species showed a bimodal activity pattern during spring and summer, and unimodal in fall. Aspidoscelis marmorata showed the smallest niche breadth in the 3 seasons. For each species, preferred body temperature and environmental temperature seem to dictate activity patterns of this lizard guild at Viesca.

Temporal niche of acoustic activity in anurans: interspecific and seasonal variation in a neotropical assemblage from south-eastern Brazil

AbstractSympatric anuran species tend to differ in their temporal niche breadth and may also have considerable seasonal variation in diel activity patterns. We studied the temporal niche breadths of six anuran species during 24 consecutive months in an area of secondary forest at the Brazilian Atlantic Rainforest. Along hourly intervals, at each of three observation points along a stream, the number of calling males of Adenomera marmorata, Eleutherodactylus parvus, Physalaemus signifer, Aplastodiscus eugenioi, Scinax hayii and S. trapicheiroi was recorded. The influence of rainfall, air humidity and temperature on the variation in the niche breadth of each species was analysed. Mean niche breadth differed for all species. Scinax trapicheiroi had the broadest niche and S. hayii had the smallest. Temporal niche breadth varied seasonally for all species. Two species (E. parvus and S. hayii) showed strong variation in the temporal niche when compared to the other species. Eleutherodactylus parvus, A. eugenioi and S. hayii were significantly affected by rainfall, air humidity and temperature. Niche overlap among species pairs also varied annually with mean temporal niche overlap being greater during the rainy season than during the dry season.

Spatial and temporal niche overlap of two mayfly species (Ephemeroptera): the role of substratum roughness and body size

Intra- and interspecific niche overlap for two mayfly species with similar life cycle timing, Rhithrogena semicolorata and Ecdyonurus sp. gr. venosus, were investigated. The nymphs were classified into 5 classes according to size and spatial overlaps are measured along a substratum roughness gradient. Substratum roughness selection was investigated by defining utilisation curves, optimum and tolerance values of the nymphs in relation to larval growth. Differences between species and size classes within each species were observed. Ecdyonurus sp. gr. venosus dominated on rough substrates, whereas R. semicolorata was most abundant on smooth substrates. An intermediate value of total interspecific substratum roughness overlap (0.49) was found. Higher intraspecific than interspecific overlap values suggested a spatial niche segregation between the two species. The results suggested that the spatial niches measured, were closer to the `fundamental niches' than could be expected if competition was acting on the two studied populations.

On the Use of the Time Axis for Ecological Separation: Diel Rhythms as an Evolutionary Constraint

On the Use of the Time Axis for Ecological Separation: Diel Rhythms as an Evolutionary Constraint

Spatial and temporal niche partitioning in grassland ants.

Species coexistence can reflect niche partitioning at several spatial and temporal scales. We measured patterns of spatial and temporal niche overlap in an Oklahoma grassland ant assemblage. Ant species foraging on a 400-m2 grid of 25 tuna-fish baits were censused hourly for one 24-h period each month for 1year. We used partial correlations to analyze pairwise associations of the four commonest species, and a null model analysis to quantify niche overlap among all seven species present. On a seasonal (monthly) time scale, niche overlap and pairwise species associations were random or aggregated, probably due to thermal constraints on ectotherms foraging in a seasonal environment. Within the warmer months of the year, there was some evidence of diurnal (24h) niche partitioning: the variance in niche overlap was often greater than expected, and common species displayed both negative and positive associations with each other and with ambient air temperature. The strongest evidence for niche partitioning was at the spatial scale of individual baits. Species occurrences at baits were dynamic, with considerable turnover in composition and significantly less spatial niche overlap than expected by chance. These results are consistent with other studies suggesting that ant species partition resources at fine spatial and temporal scales.