Comparison of Niche-Packing and Community Organization in Desert Rodents in Asia and North-America

1994 ◽  
Vol 42 (4) ◽  
pp. 479 ◽  
Author(s):  
GI Shenbrot ◽  
KA Rogovin ◽  
EJ Heske
Keyword(s):  
Species Diversity ◽  
North American ◽  
Chihuahuan Desert ◽  
Community Organization ◽  
Alpha Diversity ◽  
Mean Annual Precipitation ◽  
Spatial Organisation ◽  
Feeding Modes ◽  
Desert Rodents ◽  
Desert Rodent

We compared patterns of species diversity, locomotory morphology, feeding modes, and spatial organisation for rodent communities in four Asian deserts (Kyzylkum, Gobi, ?Thar, Negev) and one North American (Chihuahuan) desert. Deserts were similar in gamma and alpha diversity. A positive relationship between regional species diversity (and biomass) and mean annual precipitation was found. The Asian deserts showed a greater degree of divergence and specialisation between bipedal and quadrupedal forms. The range of feeding modes was similar in deserts on both continents, but the Negev was the only Asian desert in which granivory was as important as in the Chihuahuan. Temperate Asian desert rodents were organised into spatial guilds, separated primarily by characteristics of the soil and perennial vegetation. North American desert rodent species overlapped more extensively in habitat use. The similarities and differences between these deserts can be explained by their biogeographic histories.

scholarly journals Relation between plant species diversity and landscape variables in Central-European dry grassland fragments and their successional derivates

2017 ◽  
Vol 76 (2) ◽  
pp. 111-119
Author(s):  
Igor Paušič ◽  
Danijel Ivajnšič ◽  
Mitja Kaligarič ◽  
Nataša Pipenbaher
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Alpha Diversity ◽  
Shape Index ◽  
Plant Species Diversity ◽  
Lower Altitude ◽  
Dry Grassland ◽  
Central European ◽  
Landscape Variables ◽  
Habitat Specialists

AbstractA systematic field survey of an area of 843 ha in the traditional Central-European agricultural landscape of Goričko Nature Park in Slovenia revealed 80 fragments of dry semi-natural grasslands. Vascular plant species diversity was studied in relation to landscape variables and to threat (Slovenian red-listed species). Our results show that fragment size does not affect plant species diversity. In addition, fragment shape index is not related to Alpha diversity. Higher Alpha diversity was observed for abandoned grassland fragments. The lowest Alpha diversity was perceived on more mesic fragments, where habitat specialists are much scarcer. It was confirmed that the highest diversity of specialists are in the driest fragments, both still mowed and abandoned. With an increase in the number of distinctly different bordering habitat types, the total number of species per fragment generally does not increase, except in the case of those fragments that are already in different succession stages. Abandoned and typical dry grasslands are associated with a higher number of bordering habitats. Typical dry grassland fragments and abandoned ones, which probably derived mostly from drier (less productive) grasslands, are found on lower altitude and have a lower shape index. Habitat specialistsSedum sexangulare, Polygala vulgarisandSpiranthes spiralishave higher frequency in fragments with a lower shape index. This means that these oligotrophic specialists occur in smaller fragments. ButOrchis moriohas higher frequencies of occurrence on polygons with a higher shape index, which confirms the observation that this species occurs in larger and more irregular fragments, as well as close to houses and fields and along the roads.

A comparison of latitudinal species diversity patterns between riverine and terrestrial earthworms from the North American temperate zone

2020 ◽  
Vol 47 (6) ◽  
pp. 1373-1382
Author(s):  
Hiroshi Ikeda ◽  
Mac A. Callaham ◽  
Richard P. Shefferson ◽  
Evelyn S. Wenk ◽  
Carlos Fragoso
Keyword(s):  
Species Diversity ◽  
North American ◽  
Temperate Zone ◽  
Diversity Patterns ◽  
The North

Environmental correlates of herpetofaunal diversity in Costa Rica

2010 ◽  
Vol 26 (5) ◽  
pp. 521-531 ◽  
Author(s):  
David Laurencio ◽  
Lee A. Fitzgerald
Keyword(s):  
Costa Rica ◽  
Species Diversity ◽  
Beta Diversity ◽  
Geographic Distance ◽  
Alpha Diversity ◽  
High Elevation ◽  
Diversity Patterns ◽  
Regional Diversity ◽  
Environmental Correlates ◽  
High Elevation Site

Abstract:Disentangling local and historical factors that determine species diversity patterns at multiple spatial scales is fundamental to elucidating processes that govern ecological communities. Here we investigated how environmental correlates may influence diversity at local and regional scales. Primarily utilizing published species lists, amphibian and reptile alpha and beta diversity were assessed at 17 well-surveyed sites distributed among ecoregions throughout Costa Rica. The degree to which regional species diversity patterns were related to environmental variables and geographic distance was determined using Canonical Correspondence Analysis and Mantel tests. Amphibian alpha diversity was highest in lowland Pacific sites (mean = 43.3 species) and lowest at the high elevation site (9 species). Reptile alpha diversity values were high for both lowland Atlantic (mean = 69.5 species) and lowland Pacific (mean = 67 species) sites and lowest for the high elevation site (8 species). We found high species turnover between local sites and ecoregions, demonstrating the importance of beta diversity in the determination of regional diversity. For both amphibians and reptiles, beta diversity was highest between the high-elevation site and all others, and lowest among lowland sites within the same ecoregion. The effect of geographic distance on beta diversity was minor. Ecologically significant climatic variables related to rain, temperature, sunshine and insolation were found to be important determinants of local and regional diversity for both amphibians and reptiles in Costa Rica.

scholarly journals Prokaryotic Diversity in Mangrove Sediments across Southeastern China Fundamentally Differs from That in Other Biomes

mSystems ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Cui-Jing Zhang ◽  
Jie Pan ◽  
Chang-Hai Duan ◽  
Yong-Ming Wang ◽  
Yang Liu ◽  
...  
Keyword(s):  
Microbial Community ◽  
Microbial Diversity ◽  
Community Assembly ◽  
Alpha Diversity ◽  
Mean Annual Precipitation ◽  
Mangrove Sediments ◽  
Southeastern China ◽  
Deterministic Process ◽  
Deterministic Processes ◽  
Microbial Community Assembly

ABSTRACT Mangroves, as a blue carbon reservoir, provide an environment for a variety of microorganisms. Mangroves lie in special locations connecting coastal and estuarine areas and experience fluctuating conditions, which are expected to intensify with climate change, creating a need to better understand the relative roles of stochastic and deterministic processes in shaping microbial community assembly. Here, a study of microbial communities inhabiting mangrove sediments across southeastern China, spanning mangroves in six nature reserves, was conducted. We performed high-throughput DNA sequencing of these samples and compared them with data of 1,370 sediment samples collected from the Earth Microbiome Project (EMP) to compare the microbial diversity of mangroves with that of other biomes. Our results showed that prokaryotic alpha diversity in mangroves was significantly higher than that in other biomes and that microbial beta diversity generally clustered according to biome types. The core operational taxonomic units (OTUs) in mangroves were mostly assigned to Gammaproteobacteria, Deltaproteobacteria, Chloroflexi, and Euryarchaeota. The majority of beta nearest-taxon index values were higher than 2, indicating that community assembly in mangroves was better explained through a deterministic process than through a stochastic process. Mean annual precipitation (MAP) and total organic carbon (TOC) were main deterministic factors explaining variation in the microbial community. This study fills a gap in addressing the unique microbial diversity of mangrove ecosystems and their microbial community assembly mechanisms. IMPORTANCE Understanding the underlying mechanisms of microbial community assembly patterns is a vital issue in microbial ecology. Mangroves, as an important and special ecosystem, provide a unique environment for examining the relative importance of stochastic and deterministic processes. We made the first global-scale comparison and found that microbial diversity was significantly different in mangrove sediments compared to that of other biomes. Furthermore, our results suggest that a deterministic process is more important in shaping microbial community assembly in mangroves.

Desert-Dwelling Small Mammals as Granivores - Intercontinental Variations

1994 ◽  
Vol 42 (4) ◽  
pp. 543 ◽  
Author(s):  
GIH Kerley ◽  
WG Whitford
Keyword(s):  
Climate Variability ◽  
South African ◽  
Seed Production ◽  
Small Mammals ◽  
North American ◽  
Desert Plant ◽  
The North ◽  
Desert Rodents ◽  
Alternative Hypotheses ◽  
The Impact

Deserts are, by definition, environmentally similar, and this has lead to hypotheses of convergence in the properties of desert biotic communities as well as the components of these communities. There is considerable evidence for convergence in some characteristics of desert biota, ranging from plant growth forms to the well-known bipedal, nocturnal rodents. One area that has received considerable attention has been granivory by desert rodents, largely because of the effort focused on the North American desert heteromyids, and also because the process of granivory has far-reaching ramifications for desert plant communities. Specific tests for convergence in the impact of rodents as granivores, by means of bait-removal experiments, however, have shown that the high levels of seed removal by rodents in the North American deserts differs from that of rodents in the South American, Australian and South African deserts, where ants are the most important seed harvesters. The only studies to measure the impact of rodents on desert seed fluxes confirm these patterns, with rodents consuming up to 86% of seed production in North American deserts, but less than 1% of seed production in South African deserts. A review of dietary data for desert rodents confirms these trends, with little evidence for the presence of granivores in deserts besides those of North America. A variety of hypotheses have attempted to explain these variations in desert rodent granivory. These include recent extinctions of granivores, that seed burial, low soil nutrients and/or limiting seed production prevented the radiation of granivorous small mammals, and that particular deserts are too young or too recently colonised by rodents for granivorous rodents to have evolved. However, none of these hypotheses are supported by available evidence. Alternative hypotheses suggesting that climate variability may have precluded the development of specialised granivores need to be tested. In particular, more data are needed to confirm these patterns of granivory, and gain an understanding of the effects of Pleistocene and recent desert climate variability on seed production. An alternative perspective suggests that the presence of the heteromyid rodents may explain the high levels of granivory by small mammals in North American deserts. The variability in granivory by small mammals between deserts suggests that deserts will also differ in terms of anti-granivore adaptations of plants, seed fluxes and the mechanisms whereby small mammals coexist.

Trends in North American small mammals found in common barn-owl (Tyto alba) dietary studies

1991 ◽  
Vol 69 (12) ◽  
pp. 3093-3102 ◽  
Author(s):  
Donald R. Clark Jr. ◽  
Christine M. Bunck
Keyword(s):  
North America ◽  
Small Mammals ◽  
North American ◽  
Barn Owl ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Tyto Alba ◽  
Geographic Regions ◽  
Rats And Mice

Data on mammals were compiled from published studies of common barn-owl (Tyto alba) pellets. Mammalian composition of pellet samples was analyzed within geographic regions in regard to year, mean annual precipitation, latitude, and number of individual mammals in the sample. Percentages of individuals in pellets that were shrews increased whereas the percentages of rodents decreased with greater mean annual precipitation, especially in northern and western areas of North America. From the 1920s through 1980s, in northern and eastern areas the percentage of species that was shrews decreased, and in northern and central areas the percentage of individuals that was murid rats and mice increased. Human alterations of habitats during these seven decades are postulated to have caused changes in available small mammals, leading to changes in the barn-owl diet.

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